U.S. patent application number 14/901063 was filed with the patent office on 2016-07-07 for rotation transmission device.
The applicant listed for this patent is NSK LTD.. Invention is credited to Daisuke Gunji, Masafumi Hikida, Yuka Kaneko, Yasuyuki MATSUDA, Tomoharu Saito, Tetsu Takehara, Kazutaka Tanaka, Tooru Ueda, Hiroyasu Yoshioka.
Application Number | 20160195183 14/901063 |
Document ID | / |
Family ID | 52141339 |
Filed Date | 2016-07-07 |
United States Patent
Application |
20160195183 |
Kind Code |
A1 |
MATSUDA; Yasuyuki ; et
al. |
July 7, 2016 |
ROTATION TRANSMISSION DEVICE
Abstract
A rotation transmission device having a high torque measurement
resolution is provided. The rotation transmission device is
provided with: a rotary-shaft unit (6) having a first and second
rotary shaft (13, 14) combined so as to be coaxial and such that
the end sections thereof can rotate relative to each other and a
torsion bar (15) that is provided on the inner-diameter side of the
first and second rotary shafts so as to be coaxial therewith, has
one end section connected to the first rotary shaft (13), and has
the other end section connected to the second rotary shaft (14); a
first gear (7) fastened to the outer peripheral surface of the
first rotary shaft (13); a second gear (8) fastened to the outer
peripheral surface of the second rotary shaft (14); a coupling
shaft (9) provided on the inner-diameter side of the torsion bar
(15) so as to be coaxial therewith, having one end section
connected to one rotary shaft (13), and having the other end
section protruding from an end of the torsion bar (15) in the axial
direction; a first encoder disposed and fixed on the other end of
the coupling shaft (9) so as to be coaxial with the first rotary
shaft (13) and having a first detected section (39); a second
encoder fastened on the other end of the second rotary shaft (14)
so as to be close to the first encoder and having a second detected
section (40); and a sensor unit having at least one sensor (42a,
42b) that faces the first and second detected sections (39,
40).
Inventors: |
MATSUDA; Yasuyuki;
(Fujisawa-shi, Kanagawa, JP) ; Gunji; Daisuke;
(Fujisawa-shi, Kanagawa, JP) ; Hikida; Masafumi;
(Fujisawa-shi, Kanagawa, JP) ; Tanaka; Kazutaka;
(Fujisawa-shi, Kanagawa, JP) ; Ueda; Tooru;
(Fujisawa-shi, Kanagawa, JP) ; Takehara; Tetsu;
(Fujisawa-shi, Kanagawa, JP) ; Saito; Tomoharu;
(Fujisawa-shi, Kanagawa, JP) ; Yoshioka; Hiroyasu;
(Fujisawa-shi, Kanagawa, JP) ; Kaneko; Yuka;
(Fujisawa-shi, Kanagawa, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NSK LTD. |
Tokyo |
|
JP |
|
|
Family ID: |
52141339 |
Appl. No.: |
14/901063 |
Filed: |
November 8, 2013 |
PCT Filed: |
November 8, 2013 |
PCT NO: |
PCT/JP2013/080358 |
371 Date: |
December 27, 2015 |
Current U.S.
Class: |
464/97 |
Current CPC
Class: |
F16H 2059/147 20130101;
F16C 19/364 20130101; G01L 3/101 20130101; G01L 3/109 20130101;
G01L 3/104 20130101; F16C 2361/65 20130101; F16C 33/6677 20130101;
G01L 3/105 20130101; F16H 57/0037 20130101; F16C 19/463 20130101;
F16C 33/581 20130101; F16F 15/1216 20130101 |
International
Class: |
F16H 57/00 20060101
F16H057/00; G01L 3/10 20060101 G01L003/10 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 25, 2013 |
JP |
2013-132497 |
Oct 29, 2013 |
JP |
2013-224156 |
Oct 29, 2013 |
JP |
2013-224610 |
Oct 30, 2013 |
JP |
2013-225481 |
Nov 5, 2013 |
JP |
2013-229682 |
Nov 6, 2013 |
JP |
2013-229873 |
Nov 6, 2013 |
JP |
2013-229952 |
Nov 7, 2013 |
JP |
2013-231070 |
Claims
1. A rotation transmission device comprising: a rotary-shaft unit
that comprises: a first rotary shaft and a second rotary shaft that
are both hollow, and together with being arranged so as to be
concentric with each other, are combined so that the end sections
of each are able to rotate relative to each other, and in this
state are supported by a housing so as to rotate freely; and a
torsion bar that is hollow and concentrically arranged on the
inner-diameter side of the first and second rotary shafts, with one
end section being connected to the first rotary shaft so that
relative rotation is not possible, and the other end section being
connected to the second rotary shaft so that relative rotation is
not possible; a first gear that is provided in the middle section
in the axial direction of the outer-circumferential surface of the
first rotary shaft; a second gear that is provided in the middle
section in the axial direction of the outer-circumferential surface
of the second rotary shaft; a first encoder that is fastened to one
of the first and second rotary shafts so as to be concentric with
that one rotary shaft, and comprising a first detected section that
is magnetized so that the magnetic characteristics change in an
alternating manner at a uniform pitch; a second encoder that is
fastened to the other of the first and second rotary shafts so as
to be concentric with that other rotary shaft, and comprising a
second detected section that is magnetized so that the magnetic
characteristics change in an alternating manner at a uniform pitch;
and a sensor unit that is supported by the housing, and comprises
at least one sensor that faces the first and second detected
sections, and causes an output signal to change in correspondence
to the change in magnetic characteristics of a portion of the first
and second detected section where the at least one sensor
faces.
2. The rotation transmission device according to claim 1, wherein
the torsion bar comprises a spring section, which is a portion in
the middle section in the axial direction of the torsion bar that
undergoes elastic torsional deformation when torque is transmitted;
the dimensions of that spring section being larger than the space
in the axial direction between the first and second gears.
3. The rotation transmission device according to claim 2, wherein
the spring section comprises a tube section having a wall thickness
in the radial direction in the middle section in the axial
direction except for the portions of the edges on both ends in the
axial direction that is less than the portions of the edges on both
ends in the axial direction, and is such that the
inner-circumferential surface and outer-circumferential surface are
single cylindrical surfaces that are concentric with each other;
the ratio di/do of the inner-diameter dimension di and
outer-diameter dimension do of that tube section being within the
range 0.5.ltoreq.di/do.ltoreq.0.8.
4. The rotation transmission device according to claim 2, wherein
the spring section comprises a tube section having a wall thickness
in the radial direction in the middle section in the axial
direction except for the portions of the edges on both ends in the
axial direction that is less than those portions of the edges on
both ends in the axial direction, and is such that the
inner-circumferential surface and outer-circumferential surface are
single cylindrical surfaces that are concentric with each other;
the ten-point average roughness Rz of that tube section being
within the range Rz.ltoreq.22 .mu.m.
5. The rotation transmission device according to claim 1, wherein
the torsion bar is such that the one end section and the other end
section are connected to the end sections of the first and second
rotary shafts that are opposite the end sections that are combined
together.
6. The rotation transmission device according to claim 1, further
comprising a coupling shaft that is arranged on the inner-diameter
side of the torsion bar and arranged concentric with the torsion
bar, with one end section being connected to one of the rotary
shafts so that relative rotation is not possible, and the other end
section protruding in the axial direction from the end section of
the torsion bar; and wherein the first encoder is fastened to the
other end section of the coupling shaft; the second encoder is
fastened to the end section on the other end section side of the
coupling shaft of the other rotary shaft so at to be close to the
first encoder; and the first and second detected sections are
arranged so as to be close to each other.
7. The rotation transmission device according to claim 6, wherein a
sliding bearing is provided between the inner-circumferential
surface of the end section on the other end section side of the
coupling shaft of the other rotary shaft and the
outer-circumferential surface of the coupling shaft or a fitting
cylindrical section of a metal core of the first encoder that fits
on the coupling shaft.
8. The rotation transmission device according to claim 6, wherein
the coupling shaft comprises a rim section on the
outer-circumferential surface of the one end section, and the
coupling shaft is supported by that rim section being pressure
fitted with the inner-circumferential surface of the end section on
the one end side of the coupling shaft of the one rotary shaft so
that relative rotation with respect to that one rotary shaft is not
possible.
9. The rotation transmission device according to claim 6, wherein
the other rotary shaft is supported by a rolling bearing that is
located between the portion of the outer-circumferential surface of
the other rotary shaft that is near the end section on the other
end section side of the coupling shaft and the
inner-circumferential surface of the housing so as to rotate freely
with respect to the housing; and the sensor unit comprises a sensor
cover and a detecting section that is fastened to and supported by
the inside of the sensor cover; and by fastening the sensor cover
to and supporting the sensor cover by the end section of the outer
ring of the rolling bearing on the other end section side of the
coupling shaft of the other rotary shaft so that the first and
second encoders are located in a space inside the sensor cover, the
detecting section is made to face the first and second detected
sections.
10. The rotation transmission device according to claim 9, wherein
a seal device is located between the space where plural rolling
bodies of the rolling bearing are located and the space on the
inside of the sensor cover where the first and second detected
sections are located, and functions as a partition between these
spaces.
11. The rotation transmission device according to claim 6, wherein
the other rotary shaft is supported by a rolling bearing that is
located between the portion of the outer-circumferential surface of
that other rotary shaft near the end section on the other end
section side of the coupling shaft and the inner-circumferential
surface of the housing so as to rotate freely with respect to the
housing; and the second encoder is fastened around the outside of
the end section of the inner ring of the rolling bearing on the
other end section side of the coupling shaft.
12. The rotation transmission device according to claim 11 wherein
the first and second detected sections are both cylindrical shaped;
and at least one end section in the axial direction of the first
and second detected sections is arranged around the outer-diameter
side of the end section of the other rotary shaft on the other end
section side of the coupling shaft, or another part that is
fastened around the outside of that end section, in a position that
overlaps in the radial direction that end section of the other
rotary shaft or that other part.
13. The rotation transmission device according to claim 1, wherein
the first encoder is fastened to the first rotary shaft in a
position between the first and second gears in the axial direction;
and the second encoder is fastened to the second rotary shaft in a
position between the first and second gears in the axial
direction.
14. The rotating transmission device according to claim 1, wherein
the rotary-shaft unit is supported by the housing by plural rolling
bearings so as to rotate freely; and the first rotary shaft or
second rotary shaft is integrally formed with the inner ring of at
least one of the plural rolling bearings.
15. The rotation transmission device according to claim 1, wherein
the first rotary shaft or second rotary shaft is integrally formed
with the torsion bar.
16. The rotation transmission device with torque measurement device
according to claim 1, wherein the sensor unit comprises a first
sensor that faces the first detected section, and a second sensor
that faces the second detected section; and the first and second
sensors generate output signals that change in correspondence to
the change in magnetic characteristics of the portions of the first
and second detected sections that the first and second sensors
face.
17. The rotation transmission device according to claim 1, wherein
the first and second encoders are made of a magnetic material; the
first and second detected sections comprise sections with material
removed and solid sections that are arranged in an alternating
manner at a uniform pitch in the circumferential direction, and are
arranged so as to be close to each other and overlap in the radial
or axial direction; the sensor unit comprises a stator made of a
magnetic material, and plural coils that are made of one conducting
wire, and is constructed so that when a driving voltage is applied
to the conducting wire, the output current or the output voltage
from the conducting wire is used as an output signal; the stator
comprises: plural core sections that are arranged at a uniform
pitch in the circumferential direction, extend in the overlapping
direction of the first and second detected sections, and the
tip-end surfaces face one of the first and second detected sections
from one side in the overlapping direction of the first and second
detected sections; and a circular ring-shaped rim section that
connects together the base-end sections of the plural core
sections; and the plural coils are fastened one by one around the
plural core sections, and are such that the winding directions of
coils that are adjacent in the circumferential direction are
opposite each other.
18. The rotation transmission device according to claim 1, wherein
the first and second encoders are made of a magnetic material; the
first and second detected sections comprise sections with material
removed and solid sections that are arranged in an alternating
manner at a uniform pitch in the circumferential direction, and the
solid sections of the first detected section and the solid sections
of the second detected section are arranged in an alternating
manner in the circumferential direction with a space in between
each in the circumferential direction; and the sensor unit
comprises one sensor that faces the portion where the solid
sections are alternatingly arranged, and that sensor generates an
output signal that changes in correspondence to the change in the
magnetic characteristics of the portion where the sensor faces the
solid sections of the first and second detected sections are
alternatingly arranged.
19. The rotation transmission device according to claim 1, wherein
the first and second detected sections comprise a pair of
cylindrical surfaces that face each other in the radial direction
or a pair of wheel surfaces that face each other in the axial
direction, and are arranged so the S poles and N poles of these
detected sections alternate at a uniform pitch in the
circumferential direction; and the sensor unit comprises a
magnetism-detecting element or coil that is arranged between the
first and second detected sections, and the output voltage or
output current from that magnetism detecting unit, or the output
voltage or output current from the coil is used as the output
signal.
Description
TECHNICAL FIELD
[0001] The present invention relates to a rotation transmission
device that is assembled in various kinds of machinery such as an
automatic transmission for an automobile, and has a function for
transmitting torque using a rotary shaft, as well as a function for
measuring the torque that is transmitted by that rotary shaft.
BACKGROUND ART
[0002] An automatic transmission for an automobile includes a
mechanism that measures the rotational speed of a rotary shaft of
the automatic transmission, and measures the torque that the rotary
shaft transmits, and then performs transmission control for
controlling the automatic transmission itself, or output control
for controlling the output of the engine. As such a device for
measuring torque is a device disclosed in JPH01254826 (A) that
converts the amount of elastic torsional deformation of the rotary
shaft that transmits torque to a phase difference of output signals
from a pair of sensors, and measures the torque based on the phase
difference.
[0003] FIG. 66 illustrates a first example of a conventional torque
measurement device that includes this kind of construction. This
torque measurement device includes a pair of encoders 2 that are
fastened on the outside of the rotary shaft 1 at two locations in
the axial direction of the rotary shaft 1, and sensors 3 that
correspond to each of the encoders 2 and that are supported in a
housing that is not illustrated in the figure. The
outer-circumferential surfaces of these encoders 2 function as
detected sections, and the magnetic characteristics of these
encoders 2 change in an alternating manner at a uniform pitch in
the circumferential direction. The pitches at which the magnetic
characteristics vary in the circumferential direction on the
outer-circumferential surface of these encoders 2 are equal to each
other. On the other hand, the sensors 3 are arranged so that the
detecting sections of the sensors 3 face the outer-circumferential
surfaces of the encoders 2. These sensors 3 cause the output
signals that are outputted from the sensors 3 to change according
to the change in the magnetic characteristics on the
outer-circumferential surfaces of the encoders 2 that the detecting
sections face.
[0004] The output signals from the sensors 3 change periodically as
the encoders 2 rotate together with the rotary shaft 1. The
frequency and period of this change are values that correspond to
the rotational speed of the rotary shaft 1. Therefore, it is
possible to find the rotational speed of the rotary shaft 1 based
on that frequency and period. Moreover, as the rotary shaft 1
transmits torque, the rotary shaft 1 undergoes elastic torsional
deformation, which causes relative displacement between the
encoders 2. As a result, the phase difference ratio (=phase
difference/1 period) between the output signals from the sensors 3
changes. This phase difference ratio is a value that corresponds to
the amount of elastic torsional deformation of the rotary shaft 1
due to transmitting torque. Therefore, the torque that the rotary
shaft 1 transmits can be found based on this phase difference
ratio.
[0005] When trying to apply the torque measurement device of this
first example of conventional construction to an automatic
transmission for an automobile, the torsional rigidity of the
rotary shaft 1 that is the target of torque measurement is high, so
there is a problem in that it is difficult to sufficiently maintain
the amount of elastic torsional deformation of the rotary shaft 1,
and the resolution of the torque measurement becomes low. Moreover,
it is necessary to install the two sensors 3 so as to be separated
in the axial direction, so there is also a problem in that it
becomes difficult to arrange two harnesses 4 that run from these
sensors 3. Furthermore, in order to support the sensors 3 in a
highly precise relative positional relationship, it is necessary to
provide supporting and fastening sections in the housing, and thus
there is also a problem in that processing of the housing becomes
complicated.
[0006] In regard to this, JPH01254826 (A) discloses a torque
measurement device in which the sensors have a unit-like
construction. FIG. 67 illustrates a second example of a
conventional torque measurement device that has this kind of
construction. In this torque measurement device, the detected
sections of a pair of encoders 2a that are fastened at two
locations in the axial direction of the rotary shaft 1 extend
toward the center section in the axial direction, and detecting
sections of a pair of sensors of a single sensor unit 5 that is
placed in the center section in the axial direction of the rotary
shaft 1 faces the detected sections of the encoders 2a. However, in
this case of applying the torque measurement device of this second
example of conventional construction to an automatic transmission
for an automobile as well, even though the installation of the
sensor unit 5 is simplified, it does not mean that the problem of
low resolution of the torque measurement has been solved.
[0007] Moreover, JPH02017311 (U) discloses a torque measurement
device having construction that uses a torsion bar. More
specifically, the torque measurement device of this third example
of conventional construction is constructed so that encoders are
fastened to the outer-circumferential surfaces of a pair of rotary
shafts that are arranged along the same line, and these rotary
shafts are connected by a torsion bar that undergoes elastic
torsional deformation more easily than these rotary shafts. In this
case, the amount of relative displacement in the rotational
direction between the encoders can be made large due to the elastic
torsional deformation of the torsion bar that occurs when
transmitting torque, so it is possible to improve the resolution of
the torque measurement. However, even when the torque measurement
device of this third example of conventional construction is
applied to a counter shaft of an automatic transmission for an
automobile, it is difficult to sufficiently improve the resolution
of the torque measurement. In other words, an input gear and output
gear are fastened at two locations in the axial direction of the
counter shaft, and the portion of this counter shaft that undergoes
elastic torsional deformation during the transmission of torque is
only the portion that is between these gears. The space in the
axial direction of this portion is small, and it is difficult to
sufficiently lengthen the dimension in the axial direction of the
torsion bar that is to be placed in this portion, so it is not
possible to sufficiently maintain the amount of elastic torsional
deformation of the torsion bar.
[0008] As other related literature that is related to the present
invention is JP2010185478 (A). A torsion bar having high fatigue
strength and that is able to handle large stress loads, and a
manufacturing method for manufacturing that torsion bar are
disclosed in JP2010185478 (A).
RELATED LITERATURE
Patent Literature
[0009] [Patent Literature 1] JPH01254826 (A) [0010] [Patent
Literature 2] JPH02017311 (U) [0011] [Patent Literature 3]
JP2010185478 (A)
SUMMARY OF INVENTION
Problem to be Solved by Invention
[0012] The object of the present invention is to achieve
construction of a rotation transmission device that can measure
transmitted torque by using only a pair of encoders and one sensor
unit, and that can increase the resolution of the torque
measurement regardless of whether the space in the axial direction
between a pair of gears is large or small.
Means for Solving Problems
[0013] The rotation transmission device of the present invention
includes a rotary-shaft unit, a first gear, a second gear, a first
encoder, a second encoder and a sensor unit. Of these, the
rotary-shaft unit includes: a first rotary shaft and a second
rotary shaft that are both hollow, and together with being arranged
so as to be concentric with each other, are combined so that the
end sections of each are able to rotate relative to each other, and
in this state are supported by a housing so as to rotate freely;
and a torsion bar that is hollow and concentrically arranged on the
inner-diameter side of the first and second rotary shafts, with one
end section being connected to the first rotary shaft so that
relative rotation is not possible, and the other end section being
connected to the second rotary shaft so that relative rotation is
not possible.
[0014] The first gear is provided in the middle section in the
axial direction of the outer-circumferential surface of the first
rotary shaft. The second gear is provided in the middle section in
the axial direction of the outer-circumferential surface of the
second rotary shaft. The first and second gears can be made to be
separate from the first and second rotary shafts and fastened to
the middle sections in the axial direction of the
outer-circumferential surfaces of the first and second rotary
shafts, or can be integrally formed with the middle sections in the
axial direction of the outer-circumferential surfaces of the first
and second rotary shafts.
[0015] The first encoder is fastened to one of the first and second
rotary shafts so as to be concentric with the one rotary shaft, and
has a first detected section that is magnetized so that the
magnetic characteristics change in an alternating manner at a
uniform pitch. Moreover, a second encoder is fastened to the other
of the first and second rotary shafts so as to be concentric with
the other rotary shaft, and has a second detected section that is
magnetized so that the magnetic characteristics change in an
alternating manner at a uniform pitch. The first and second
detected sections can be circular ring-shaped, or can be circular
disk-shaped. The first and second encoders can be made separate
from the rotary shafts, or members that rotate in synchronization
with the rotary shafts and fastened to and supported by the rotary
shafts or these members, or can be integrally formed with these
members.
[0016] The sensor unit is supported by the housing, and comprises
at least one sensor that faces the first and second detected
sections, and causes an output signal to change in correspondence
to the change in magnetic characteristics of a portion of the first
and second detected section where the at least one sensor
faces.
[0017] For example, the first encoder is directly or indirectly
fastened to an input shaft, which is the first rotary shaft, and
the second encoder is directly or indirectly fastened to an output
shaft, which is the second rotary shaft.
[0018] In one form of the present invention, the torsion bar
includes a spring section, which is a portion in the middle section
in the axial direction of the torsion bar that undergoes elastic
torsional deformation when torque is transmitted; the dimensions of
that spring section being larger than the space in the axial
direction between the first and second gears.
[0019] In this case, preferably, the spring section includes a tube
section having a wall thickness in the radial direction in the
middle section in the axial direction except for the portions of
the edges on both ends in the axial direction that is less than
those portions of the edges on both ends in the axial direction,
and is such that the inner-circumferential surface and
outer-circumferential surface are single cylindrical surfaces that
are concentric with each other; the ratio di/do of the
inner-diameter dimension di and outer-diameter dimension do of that
tube section being within the range 0.5.ltoreq.di/do.ltoreq.0.8.
Alternatively or additionally, the ten-point average roughness Rz
of that tube section is within the range Rz.ltoreq.22 .mu.m.
[0020] In one form of the present invention, one end section and
the other end section of the torsion bar are connected to the end
sections of the first and second rotary shafts that are opposite
the end sections that are combined together. For example, when the
end sections of the first and second rotary shafts that are
combined together are one end section of the second rotary shaft
and the other end section of the first rotary shaft, the one end
section of the torsion bar is connected to the one end section of
the first rotary shaft, and the other end section of the torsion
bar is connected to the other end section of the second rotary
shaft.
[0021] In one form of the present invention, there is a coupling
shaft that is arranged on the inner-diameter side of the torsion
bar and arranged concentric with the torsion bar, with one end
section thereof being connected to the one rotary shafts so that
relative rotation is not possible, and the other end section
protruding in the axial direction from the end section of the
torsion bar, the first encoder is fastened to the other end section
of the coupling shaft, the second encoder is fastened to the end
section of the other rotary shaft on the other end section side of
the coupling shaft so as to be close to the first encoder, and the
first and second detected sections are arranged so as to be close
to each other (for example, arranged with a space between of less
than 10 mm, and more preferably, less than 5 mm). For example, when
the end sections of the first and second rotary shafts that are
combined together are taken to be one end section of the second
rotary shaft and the other end section of the first rotary shaft,
one end section of the torsion bar is connected to the one end
section of the first rotary shaft, and the other end section of the
torsion bar is connected to the other end section of the second
rotary shaft, one end section of the coupling shaft is connected to
the one end section of the first rotary shaft, and the other end
section of the coupling shaft protrudes in the axial direction of
the other end section of the second rotary shaft, and together with
the first encoder being fastened to the other end section of the
coupling shaft, the second encoder is fastened to the other end
section of the second rotary shaft. In this form, the first and
second encoders and the sensor unit are arranged on one end section
in the axial direction of the rotary-shaft unit (the one end
section in the axial direction or the other end section in the
axial direction).
[0022] In this case, preferably, a sliding bearing is provided
between the inner-circumferential surface of the end section of the
other rotary shaft on the other end section side of the coupling
shaft and the outer-circumferential surface of the coupling shaft
or a fitting cylindrical section of a metal core of the first
encoder that fits on the coupling shaft.
[0023] Alternatively, a rim section is provided on the
outer-circumferential surface of the one end section of the
coupling shaft, and the coupling shaft is supported by the one
rotary shaft so that relative rotation is not possible with the rim
section being pressure fitted with the inner-circumferential
surface of the end section of the one rotary shaft on the one end
side of the coupling shaft.
[0024] Alternatively, the other rotary shaft is supported by the
housing so as to rotate freely using a rolling bearing that is
located between the portion of the outer-circumferential surface of
the other rotary shaft that is near the end section on the other
end section side of the coupling shaft and the
inner-circumferential surface of the housing; and the sensor unit
includes a sensor cover and a detecting section that is fastened to
and supported by the inside of the sensor cover; and by fastening
the sensor cover to and supporting the sensor cover by the end
section of the outer ring of the rolling bearing on the other end
section side of the coupling shaft of the other rotary shaft so
that the first and second encoders are located in a space inside
the sensor cover, the detecting section is made to face the first
and second detected sections. For example, the second rotary shaft
is supported by the housing by a rolling bearing that is located
between a portion of the second rotary shaft near the other end and
the inner-circumferential surface of the housing, the sensor cover
of the sensor unit is fastened to and supported by the end section
of the outer ring of the rolling bearing on the other end section
side of the second rotary shaft, and the first encoder that is
fastened to the other end section of the coupling shaft, and the
second encoder that is fastened to the other end section of the
second rotary shaft are located in a space inside the sensor cover.
In this case, preferably, a seal device is located between the
space where plural rolling bodies of the rolling bearing are
located and the space on the inside of the sensor cover where the
first and second detected sections are located, and functions as a
partition between these spaces.
[0025] Alternatively, the other rotary shaft is supported by the
housing so as to rotate freely using a rolling bearing that is
located between the portion of the outer-circumferential surface of
the other rotary shaft near the end section on the other end
section side of the coupling shaft and the inner-circumferential
surface of the housing, and the second encoder is fastened around
the outside of the end section of the inner ring of the rolling
bearing on the other end section side of the coupling shaft. For
example, the second rotary shaft is supported by the housing using
a rolling bearing that is located between a portion of the
outer-circumferential surface of the second rotary shaft near the
other end and the inner-circumferential surface of the housing, and
the second encoder is fastened around the outside of the other end
section of the inner ring of the rolling bearing.
[0026] In this case, the first and second detected sections can
both be cylindrical shaped, and at least one end section in the
axial direction of the first and second detected sections can be
arranged around the outer-diameter side of the end section of the
other rotary shaft on the other end section side of the coupling
shaft, or of another part that is fastened around the outside of
the end section, in a position that overlaps in the radial
direction that end section of the other rotary shaft or the other
part. For example, at least part of the cylindrical shaped first
and second detected sections is arranged around the outer-diameter
side of the other end section of the second rotary shaft or of
construction that is fastened to the end section, in a position
that overlaps these in the radial direction.
[0027] In one form of the present invention, the first encoder is
fastened to the first rotary shaft in a position between the first
and second gears in the axial direction, and the second encoder is
fastened to the second rotary shaft in a position between the first
and second gears in the axial direction. That is to say, in this
form, the first and second encoders and the sensor unit are
arranged in the middle section in the axial direction of the
rotary-shaft unit.
[0028] In one form of the present invention, the rotary-shaft unit
is supported by the housing by plural rolling bearings so as to
rotate freely; and the first rotary shaft or second rotary shaft is
integrally formed with the inner ring of at least one of the plural
rolling bearings.
[0029] In one form of the present invention, the first rotary shaft
or second rotary shaft is integrally formed with the torsion
bar.
[0030] In one form of the present invention, the sensor unit
includes a first sensor that faces the first detected section, and
a second sensor that faces the second detected section, and the
first and second sensors generate output signals that change in
correspondence to the change in magnetic characteristics of the
portions of the first and second detected sections that the first
and second sensors face; where the first and second detected
sections can both be circular ring-shaped and arranged close to
each other in the axial direction of the rotary-shaft unit; and in
that case, the first and second sensors are made to face the first
and second detected sections in the radial direction of the
rotary-shaft unit. Moreover, the first and second detected sections
can both be circular disk-shaped and arranged close to each other
in the radial direction of the rotary-shaft unit; and in that case,
the first and second sensors are made to face the first and second
detected sections in the axial direction of the rotary-shaft
unit.
[0031] In one form of the present invention, the first and second
encoders are made of a magnetic material; the first and second
detected sections include sections with material removed and solid
sections that are arranged in an alternating manner at a uniform
pitch in the circumferential direction, and are arranged so as to
be close to each other and overlap in the radial or axial
direction; the sensor unit includes a stator made of a magnetic
material, and plural coils that are made of one conducting wire,
and is constructed so that when a driving voltage is applied to the
conducting wire, the output current or the output voltage from the
conducting wire is used as an output signal; the stator includes:
plural core sections that are arranged at a uniform pitch in the
circumferential direction, extend in the overlapping direction of
the first and second detected sections, and the tip-end surfaces
face one of the first and second detected sections from one side in
the overlapping direction of the first and second detected
sections; and a circular ring-shaped rim section that connects
together the base-end sections of the plural core sections; and the
plural coils are fastened one by one around the plural core
sections, and are such that the winding directions of coils that
are adjacent in the circumferential direction are opposite each
other.
[0032] In one form of the present invention, the first and second
encoders are made of a magnetic material; the first and second
detected sections include sections with material removed and solid
sections that are arranged in an alternating manner at a uniform
pitch in the circumferential direction, and the solid sections of
the first detected section and the solid sections of the second
detected section are arranged in an alternating manner in the
circumferential direction with a space in between each in the
circumferential direction; and the sensor unit includes one sensor
that faces the portion where the solid sections of the first and
second detected sections are alternatingly arranged, and the sensor
generates an output signal that changes in correspondence to the
change in the magnetic characteristics of the portion where the
sensor faces the solid sections of the first and second detected
sections are alternatingly arranged.
[0033] In one form of the present invention, the first and second
detected sections include a pair of cylindrical surfaces that face
each other in the radial direction or a pair of circular ring
surfaces that face each other in the axial direction, and are
arranged so the S poles and N poles of these detected sections
alternate at a uniform pitch in the circumferential direction; and
the sensor unit includes a magnetism-detecting element or coil that
is arranged between the first and second detected sections, and the
output voltage or output current from that magnetism detecting
unit, or the output voltage or output current from the coil is used
as the output signal.
[0034] Furthermore, preferably the end sections of the first and
second rotary shafts are combined in a state in which displacement
in a direction in the axial direction toward each other is
prevented, the first and second gears are both helical gears, and
the directions of inclination of the first and second gears are
regulated so as to be directions in which the gear reaction forces
in the axial direction that act on the first and second gears
during forward operation of the first and second gears (rotation in
a direction of rotation that occurs often during use, for example,
rotation when the automobile is moving forward) are toward each
other (press toward each other).
[0035] Moreover, preferably, one of the combination cylindrical
sections of the first combination cylindrical section that is
provided on the other end section of the first rotary shaft and the
second combination cylindrical section that is provided on one end
section of the second rotary shaft is inserted into the
inner-diameter side of the other combination cylindrical section, a
radial bearing (radial rolling bearing, or radial sliding bearing)
is placed between the opposing circumferential surfaces of the
first and second combination cylindrical sections, and a thrust
bearing (thrust rolling bearing, or thrust sliding bearing) is
placed between a stepped surface that is provided on the base-end
section of the outer-circumferential surface of one of the
combination cylindrical sections, and the tip-end surface of the
other combination cylindrical section.
[0036] In this case, it is possible to use for example, a circular
disk shaped thrust washer that is held between the stepped surface
and the tip-end surface as the thrust bearing.
[0037] In that case, preferably a pair of sections with material
removed that connect a pair of spaces that exist in positions on
both sides in the radial direction of the portion between the
stepped surface and the tip-end surface are formed at one or plural
location in the circumferential direction of the thrust washer
(preferably, plural evenly spaced locations). As the sections with
material removed, it is possible to use slits or through holes that
pass through both side surfaces of the thrust washer, or it is also
possible to use concave grooves that are provided in at least one
of the side surfaces of the thrust washer.
[0038] Moreover, preferably the outer-circumferential edge of the
thrust washer protrudes outward in the radial direction from a
portion between the stepped surface and the tip-end surface, and a
reinforcing cylindrical section is formed around the entire
outer-circumferential edge.
[0039] Furthermore, preferably, a first male spline section that
has a first plating layer on the surface layer thereof is provided
on the outer-circumferential surface of one end section of the
torsion bar, and a first female spline section that is able to
engage with the first male spline section is provided on the
inner-circumferential surface of the first rotary shaft. Of these,
the metal of the first plating layer is a metal that is softer than
the metal of the torsion bar and first rotary shaft. By pressure
fitting the first male spline section into the first female spline
section with interference that is less than the thickness dimension
of the first plating layer in the free state (state in which no
external forces act) the spline sections are connected with no
looseness in the circumferential direction. Together with this, a
second male spline section having a second plating layer on the
surface layer thereof is provided on the outer-circumferential
surface of the other end section of the torsion bar, and a second
female spline section that is able to engage with the second male
spline section is provided on the inner-circumferential surface of
the second rotary shaft. The metal of the second plating layer is a
metal that is softer than the metal of the torsion bar and second
rotary shaft. By pressure fitting the second male spline section
into the second female spline section with interference that is
less than the thickness dimension of the second plating layer in
the free state (state in which no external forces act) the spline
sections are connected with no looseness in the circumferential
direction. In this case, the metal material of the first and second
plating layers is copper or nickel.
Effect of Invention
[0040] In the case of the rotation transmission device of the
present invention, the output signal from the sensor unit changes
in correspondence to the rotational speed due to the first and
second encoders (first and second detected sections) rotating
together with the rotary-shaft unit (first and second rotary
shafts). Therefore, when necessary, it is possible to measure the
rotational speed based on the output signal from the sensor unit.
Moreover, when the rotary-shaft unit transmits torque between the
first and second gears, there is relative displacement in the
direction of rotation between the first and second gears (between
the first and second rotary shafts, and between the first and
second encoders) as elastic torsional deformation occurs in the
middle section in the axial direction of the torsion bar. As a
result of this kind of relative displacement in the direction of
rotation between the first and second encoders, the output signal
from the sensor unit changes in correspondence to that relative
displacement (size of the torque). Therefore, it is possible to
measure the torque based on the output signal from the sensor
unit.
[0041] Particularly, in the case of the present invention, the
first rotary shaft that is provided with the first gear in the
middle section in the axial direction of the outer-circumferential
surface thereof, and the second rotary shaft that is provided with
the second gear in the middle section in the axial direction of the
outer-circumferential surface are both hollow, the torsion bar is
arranged on the inner-diameter side of these rotary shafts and both
end sections of the torsion bar are connected to these rotary
shafts so that no relative rotation is possible. Therefore, for
example, it is possible to make the dimension in the axial
direction of the middle section in the axial direction of the
torsion bar greater than the space in the axial direction between
the first and second gears, and to sufficiently maintain the amount
of elastic torsional deformation of the middle section in the axial
direction of the torsion bar that occurs when torque is
transmitted. As a result, the case of the present invention differs
from construction in which the rotary-shaft unit is one rotary in
that it is possible to sufficiently increase the amount of relative
displacement in the direction of rotation between the first and
second gears (first and second rotary shaft, first and second
encoders) that occurs when torque is transmitted, regardless of
whether the space in the axial direction between the first and
second gears is large or small. Therefore, it is possible to
sufficiently increase the resolution of the torque measurement.
[0042] Moreover, in the case of the present invention, by adjusting
the dimension in the radial direction and the dimension in the
axial direction of the middle section in the axial direction of the
torsion bar during the design stage, it is possible to easily
adjust the torsional rigidity of the middle section in the axial
direction. Therefore, when compared with construction in which the
rotary-shaft unit is a single rotary shaft, it is easy to plan and
design the relationship (gain) between the torque and the amount of
relative displacement in the direction of rotation of the first and
second encoders.
[0043] In one form of the present invention, the first and second
encoders can be arranged so as to be concentrated at one end
section of the rotary-shaft unit, or more specifically, at one end
section of the input shaft, which is the first rotary shaft, or the
other end section of the output shaft, which is the second rotary
shaft. Therefore, the sensor unit can be supported by a portion of
the housing that is near the end section having high rigidity, and
thus it is possible to maintain precision of torque measurement by
the sensor unit regardless of deformation of the housing due to
gear reaction forces in the radial direction that act on the first
and second gears (input gear and output gear) when torque is being
transmitted.
[0044] Furthermore, in one form of the present invention, only one
sensor is used, so only one harness that leads from the sensor unit
needs to be used, and that harness can be easily installed.
Moreover, only one support and fastening section needs to be
provided in the housing for the sensor unit, so processing the
housing can be performed easily.
BRIEF DESCRIPTION OF DRAWINGS
[0045] FIG. 1 is a perspective view illustrating a rotation
transmission device of a first example of an embodiment of the
present invention;
[0046] FIG. 2 is a side view of the rotation transmission device
illustrated in FIG. 1;
[0047] FIG. 3 is an end view of the other end side of the rotation
transmission device illustrated in FIG. 1;
[0048] FIG. 4 is an end view of the one end side of the rotation
transmission device illustrated in FIG. 1;
[0049] FIG. 5 is an exploded perspective view of the rotation
transmission device illustrated in FIG. 1;
[0050] FIG. 6 is a cross-sectional view of section a-a in FIG. 3 of
the rotation transmission device illustrated in FIG. 1;
[0051] FIG. 7 is an enlarged view of the other end section of the
rotation transmission device illustrated in FIG. 1;
[0052] FIG. 8 is an enlarged view of area b in FIG. 6 (where the
end sections of the input shaft and output shaft are combined
together);
[0053] FIG. 9 is a view as seen from the outer-diameter side of
part in the circumferential direction of the first detected section
and second detected section of the encoder of the rotation
transmission device illustrated in FIG. 1;
[0054] FIG. 10 is an enlarged cross-sectional view of the area of
the rotation transmission device illustrated in FIG. 1 where the
sensor unit faces the encoders;
[0055] FIG. 11A to FIG. 11C are perspective views that illustrate
three examples of a thrust washer that can be applied in the
rotation transmission device illustrated in FIG. 1;
[0056] FIG. 12 is a cross-sectional view for explaining the torque
transmission path in the rotation transmission device illustrated
in FIG. 1;
[0057] FIG. 13 is a view as seen from the outer-diameter side of
the a portion in the circumferential direction of the first
detected section and second detected section of the encoder in a
rotation transmission device of a second example of an embodiment
of the present invention;
[0058] FIG. 14 is an enlarged cross-sectional view of the area
where the sensor unit faces the encoders in the rotation
transmission device of the second example of an embodiment of the
present invention;
[0059] FIG. 15A is an end view of a first encoder, and FIG. 15B is
an end view of a second encoder of the rotation transmission device
of a third example of an embodiment of the present invention;
[0060] FIG. 16 is an enlarged cross-sectional view of the area
where the sensor unit faces the encoders in the rotation
transmission device of the third example of an embodiment of the
present invention, and illustrates a state in which the first
encoder and second encoder are joined by pins;
[0061] FIG. 17 is a perspective view of a first encoder and a
second encoder of a rotation transmission device of a fourth
example of an embodiment of the present invention;
[0062] FIG. 18A is an end view of a first encoder, and FIG. 18B is
an end view of a second encoder in a rotation transmission device
of a fifth example of an embodiment of the present invention;
[0063] FIG. 19 is an enlarged cross-sectional view of a part in the
circumferential direction of an involute spline engagement between
a torsion bar and input shaft or output shaft in a rotation
transmission device of a sixth example of an embodiment of the
present invention;
[0064] FIG. 20 is an enlarged cross-sectional view of part in the
circumferential direction of the involute spline engagement
illustrated in FIG. 19, and illustrates a state before providing a
plating layer on the surface of the male involute spline
section;
[0065] FIG. 21 is a graph illustrating the relationship between the
sensor output and the transmitted torque in the rotation
transmission device of the sixth example of an embodiment of the
present invention;
[0066] FIG. 22 is an enlarged cross-sectional view of one end of a
rotation transmission device of a seventh example of an embodiment
of the present invention;
[0067] FIG. 23 is an enlarged perspective view of one end of a
coupling shaft that is used in the seventh example of an embodiment
of the present invention;
[0068] FIG. 24 is a cross-sectional view in the axial direction
that illustrates a rotation transmission device together with the
sensor of an eighth example of an embodiment of the present
invention;
[0069] FIG. 25 is an enlarged cross-sectional view of the other end
section of a rotation transmission device of a ninth example of an
embodiment of the present invention;
[0070] FIG. 26 is an end view of the other end side of the rotation
transmission device illustrated in FIG. 25;
[0071] FIG. 27 is a cross-sectional view of section c-c in FIG. 25
of the rotation transmission device illustrated in FIG. 25;
[0072] FIG. 28 is an exploded perspective view of the first
encoder, the second encoder and the sensor unit of the rotation
transmission device illustrated in FIG. 25;
[0073] FIG. 29A is a view of a part in the circumferential
direction of the area where the sensor unit faces the encoders in
the rotation transmission device illustrated in FIG. 25, and
illustrates a state in which torque is not transmitted; FIG. 29B
illustrates this part in a state in which torque is transmitted;
and FIG. 29C is a graph illustrating the output signals from the
sensor unit of this device when torque is not transmitted and when
torque is transmitted;
[0074] FIG. 30 is an enlarged vice of the other end section of a
rotation transmission device of a tenth example of an embodiment of
the present invention;
[0075] FIG. 31 is a view as seen from the outer-diameter side of an
encoder of the rotation transmission device illustrated in FIG.
30;
[0076] FIG. 32 is an end view of the other end section of the
rotation transmission device illustrated in FIG. 30, and
illustrates a state in which the sensor unit is omitted;
[0077] FIG. 33 is an exploded perspective view of the encoders of
the rotation transmission device illustrated in FIG. 30, and
illustrates a state in which the first encoder and second encoder
are separated;
[0078] FIG. 34A is a graph for the rotation transmission device of
the tenth example of an embodiment of the present invention, and
illustrates the output signal of the sensor unit when torque is not
transmitted; and FIG. 34B is a graph that illustrates the output
signal of the sensor unit when torque is transmitted;
[0079] FIG. 35 is a graph for the rotation transmission device of
the tenth example of an embodiment of the present invention, and
illustrates the relationship between the duty ratio s of the output
signal of the sensor and the torque;
[0080] FIG. 36 is an enlarged cross-sectional view that illustrates
the other end section of a rotation transmission device of an
eleventh example of an embodiment of the present invention;
[0081] FIG. 37 is an end view of the other end side of the rotation
transmission device illustrated in FIG. 36;
[0082] FIG. 38 is an exploded perspective view of the encoders of
the rotation transmission device illustrated in FIG. 36, and
illustrates a state in which a first encoder and a second encoder
are separated;
[0083] FIG. 39 is an enlarged cross-sectional view of the other end
section of a rotation transmission device of a twelfth example of
an embodiment of the present invention;
[0084] FIG. 40 is an end view of the other end side of the rotation
transmission device illustrated in FIG. 39;
[0085] FIG. 41A is a schematic drawing illustrating the positional
relationship between the magnetic poles of the first detected
section and second detected section and the detecting section of
the sensor in the area where the sensor unit faces the encoders in
the rotation transmission device illustrated in FIG. 39 in a state
in which torque is not transmitted; and FIG. 41B illustrates that
positional relationship in a state in which torque is
transmitted;
[0086] FIG. 42 is a graph illustrating the output signal from the
sensor unit of the rotation transmission device of the twelfth
example of an embodiment of the present invention;
[0087] FIG. 43 is a cross-sectional view illustrating a rotation
transmission device of a thirteenth example of an embodiment of the
present invention;
[0088] FIG. 44 is a cross-sectional view illustrating a rotation
transmission device of a fourteenth example of an embodiment of the
present invention;
[0089] FIG. 45 is a cross-sectional view illustrating a rotation
transmission device of a fifteenth example of an embodiment of the
present invention;
[0090] FIG. 46 is a cross-sectional view illustrating a rotation
transmission device of a sixteenth example of an embodiment of the
present invention;
[0091] FIG. 47 is a cross-sectional view illustrating a rotation
transmission device of a seventeenth example of an embodiment of
the present invention;
[0092] FIG. 48 is an enlarged view illustrating the section where
the end sections of the input shaft and output shaft of a rotation
transmission device of an eighteenth example of the present
invention are combined together;
[0093] FIG. 49 is an enlarged view illustrating the section where
the end sections of the input shaft and output shaft of a rotation
transmission device of a nineteenth example of the present
invention are combined together;
[0094] FIG. 50 is a cross-sectional view illustrating the torsion
bar of a rotation transmission device of a twentieth example of an
embodiment of the present invention;
[0095] FIG. 51 is a cross-sectional view of a device that was used
in testing that was performed for confirming the effect on the
durability and precision of torque measurement for the rotation
transmission device of the twentieth example of an embodiment of
the present invention;
[0096] FIG. 52 is a cross-sectional view illustrating a rotation
transmission device of a twenty-first example of an embodiment of
the present invention;
[0097] FIG. 53 is a cross-sectional view illustrating a rotation
transmission device of a twenty-second example of an embodiment of
the present invention;
[0098] FIG. 54 is a cross-sectional view illustrating a rotation
transmission device of a twenty-third example of an embodiment of
the present invention;
[0099] FIG. 55 is a cross-sectional view illustrating a rotation
transmission device of a twenty-fourth example of an embodiment of
the present invention;
[0100] FIG. 56 is a cross-sectional view illustrating a rotation
transmission device of a twenty-fifth example of an embodiment of
the present invention;
[0101] FIG. 57 is an enlarged cross-sectional view of the other end
section of the rotation transmission device illustrated in FIG.
56;
[0102] FIG. 58 is an enlarged cross-sectional view illustrating one
end section of a rotation transmission device of a twenty-sixth
example of an embodiment of the present invention;
[0103] FIG. 59 is an enlarged cross-sectional view illustrating the
other end section of a rotation transmission device of a
twenty-seventh example of an embodiment of the present
invention;
[0104] FIG. 60 is an end view of the other end section of the
rotation transmission device illustrated in FIG. 59;
[0105] FIG. 61 is an enlarged cross-sectional view illustrating the
other end section of a rotation transmission device of a
twenty-eighth example of an embodiment of the present
invention;
[0106] FIG. 62 is a side view illustrating a rotation transmission
device of a twenty-ninth example of an embodiment of the present
invention;
[0107] FIG. 63 is a cross-sectional view of section d-d in FIG. 62
of the rotation transmission device illustrated in FIG. 62;
[0108] FIG. 64 is a cross-sectional view of section e-e in FIG. 62
of the rotation transmission device illustrated in FIG. 62;
[0109] FIG. 65 is a cross-sectional view of section f-f in FIG. 63
of the rotation transmission device illustrated in FIG. 62;
[0110] FIG. 66 is a side view illustrating a torque measurement
device of a first example of conventional construction; and
[0111] FIG. 67 is a side view illustrating a torque measurement
device of a second example of conventional construction, and
illustrates a state in which part is cut away.
MODES FOR CARRYING OUT INVENTION
First Example
[0112] FIG. 1 to FIG. 12 illustrate a first example of an
embodiment of the present invention. The rotation transmission
device of this example is incorporated and used with a counter
shaft and counter gear portion of an automatic transmission for an
automobile such as a front-wheel drive automobile or a four-wheel
drive automobile that uses the same motor and transmission
arrangement as a front-wheel drive automobile in which a so-called
transverse engine is mounted. The rotation transmission device of
this example includes: a rotary-shaft unit 6 that functions as a
counter shaft; a first gear, which is an input gear 7, and a second
gear, which is an output gear 8, that function as counter gears; a
coupling shaft 9, a first encoder 10, a second encoder 11 and one
sensor unit 12.
[0113] The rotary-shaft unit 6 includes: an input shaft 13, which
is a hollow first rotary shaft; an output shaft 14, which is a
hollow second rotary shaft; and a hollow torsion bar 15. Both the
input shaft 13 and the output shaft 14 are formed into a
cylindrical shape using steel, are arranged concentric with each
other, and the end sections of the input shaft 13 and the output
shaft 14 (the other end section of the input shaft 13 and the one
end section of the output shaft 14) are combined together so as to
be able to rotate relative to each other. In order to simplify the
explanation, the side of the rotary-shaft unit 6 where the input
gear 7 and input shaft 13 are located is called the one end side,
and the side where the output gear 8 and the output shaft 14 are
located is cased the other end side. In this example, in order to
combine the end sections of the input shaft 13 and the output shaft
14 together so as to be able to rotate relative to each other, an
input-side combination cylindrical section 16, which is a first
combination cylindrical section, is provided on the other end
section of the input shaft 13, and an output-side combination
cylindrical section 17, having an inner diameter that is larger
than the diameter of the input-side combination cylindrical section
16, is provided on the one end section of the output shaft 14. The
input-side combination cylindrical section 16 is inserted into the
inner-diameter side of the output-side combination cylindrical
section 17. Moreover, a radial needle bearing 18 is provided
between the cylindrical shaped circumferential surfaces of the
input-side and output side combination cylindrical sections 16, 17
that face each other. Furthermore, a circular disk-shaped thrust
washer 21, which is a thrust sliding bearing, is held between a
stepped surface 19 that is provided on the base end section of the
outer-circumferential surface of the input-side combination
cylindrical section 16 and the tip-end surface 20 of the
output-side combination cylindrical section 17. By using this kind
of construction, the end sections of the input shaft 13 and the
output shaft 14 are combined together in a state so that relative
rotation is possible, and so that displacement in the axial
direction toward each other is prevented.
[0114] In this example, in the thrust washer 21, as illustrated in
detail in FIG. 11A, slits 22 that are long in the radial direction
are formed by removing material at plural locations that are
uniformly spaced in the circumferential direction of a circular
disk-shaped main portion so as to be open on the
inner-circumferential edge of the main portion. Moreover, a
reinforcing cylindrical section 23 that is bent in the radial
direction at a right angle from the outer-circumferential edge of
the main portion of the thrust washer 21 is formed around the
entire outer-circumferential edge. The thrust washer 21 is fitted
around the base end section of the input-side combination
cylindrical section 16 with the edge of the tip end of the
reinforcing cylindrical section 23 facing the one end side of the
input shaft 13 so that there is no large looseness in the radial
direction. The middle section in the radial direction of the main
portion of the thrust washer 21 is held between the stepped surface
19 and the tip-end surface 20. In this state, the slits 22 connect
a pair of spaces that exist on both sides in the radial direction
of the portion between the stepped surface 19 and the tip-end
surface 20 with each other. In other words, in order to achieve
this kind of connected state, the diameter of the inscribed circle
of the slits 22 (the inner diameter of the main portion of the
thrust washer 21) is made to be smaller than the diameter of the
inner-circumferential edge of the tip-end surface 20, and the
diameter of the circumscribed circle of the slits 22 is made to be
larger than the diameter of the outer-circumferential edge of the
tip-end surface 20.
[0115] The torsion bar 15 is formed into a cylindrical shape using
a steel alloy such as carbon steel, and is concentrically arranged
on the inner-diameter side of the input shaft 13 and output shaft
14. One end section of the torsion bar 15 is connected to the input
shaft 13 so that relative rotation is not possible, and the other
end section is connected to the output shaft 14 so that relative
rotation is not possible. In this example, in order to achieve this
kind of connected state, the outer-diameter dimensions of both end
sections of the torsion bar 15 are made to be a little less than
the outer-diameter dimension of the middle section of the torsion
bar 15, and the outer-circumferential surfaces of both end sections
of the torsion bar 15 fit with the portion near one end of the
inner-circumferential surface of the input shaft 13 and with the
portion near the other end of the inner-circumferential surface of
the output shaft 14 so that relative rotation is not possible. More
specifically, an involute spline connection 24a is formed by
fitting a first male involute spline section 62, which is a first
male spline section that is provided on the outer-circumferential
surface of one end section of the torsion bar 15, with a first
female involute spline section 63, which is a first female spline
section that is provided on the inner-circumferential surface of
the one end section of the input shaft 13 so that there is no
looseness in the circumferential direction. Moreover, an involute
spline connection 24b is formed by fitting a second male involute
spline section 64, which is a second male spline section that is
provided on the outer-circumferential surface of the other end
section of the torsion bar 15, with a second female involute spline
section 65, which is a second female spline section that is
provided on the inner-circumferential surface of the other end
section of the input shaft 14 so that there is no looseness in the
circumferential direction. It is also possible to use other
construction for preventing rotation such as a key connection as
the connections between the torsion bar 15 and the input shaft 13
and output shaft 14. By holding the torsion bar 15 on both sides in
the axial direction by a pair of retaining rings 25a, 25b that are
fastened around the inner-circumferential surfaces of the input
shaft 13 and output shaft 14, the torsion bar 15 is prevented from
displacing in the axial direction. In this example, the dimension L
of the portion in the middle section in the axial direction of the
torsion bar 15 that undergoes elastic torsional deformation when
torque is transmitted (portion that is between the involute spline
connections 24a, 24b) is made to be larger than the space W in the
axial direction between the input gear 7 and output gear 8 (L>W)
(in the example in the figures, L is a little over 4 times W).
[0116] The input gear 7 is a helical gear that is formed using a
steel alloy such as carbon steel, and is fastened around the
outside of the middle section of the input shaft 13. The connection
between the inner-circumferential surface of the input gear 7 and
the outer-circumferential surface of the input shaft 13 is formed
by arranging a cylindrical connecting section 26a that is for
maintaining concentricity (connecting section that is formed by
pressure fitting together the cylindrical surface sections of the
inner-circumferential surface of the input gear 7 and
outer-circumferential surface of the input shaft 13) and an
involute spline connection 24c that is for preventing relative
rotation so as to be adjacent to each other in the axial direction.
Moreover, positioning the input gear 7 in the axial direction with
respect to the input shaft 13 is accomplished by bringing the
inner-circumferential portion of the other end side of the input
gear 7 in contact with a stepped surface 27 that is formed on a
portion of the middle section of the outer-circumferential surface
of the input shaft 13 that is near the other end. In this example,
a parking-lock gear 28 is integrally formed with the
inner-circumferential portion of the side surface of the other end
side of the input gear 7. When the parking lock is engaged, the
tip-end section of a locking member (not illustrated in the
figures) engages with a portion in the circumferential direction of
the outer-circumferential surface of the parking-lock gear 28,
which makes rotation of the rotary-shaft unit 6 impossible. On the
other hand, the output gear 8 is also a helical gear that is formed
using a steel alloy such as carbon steel, and is integrally formed
with the output shaft 14 in a portion near one end of the middle
section of the outer-circumferential surface of the output shaft
14. It is also possible to separately form the output gear 8 and
fasten the output gear 8 around the outside of the output shaft 14.
In this example, when the rotary-shaft unit 6 is rotating in the
forward direction (when the automobile is advancing in a forward
direction), the torque that is inputted to the input shaft 13 from
the input gear 7 is transmitted to the output shaft 14 by way of
the torsion bar 15 and outputted from the output gear 8. When this
happens, the middle section in the axial direction of the torsion
bar 15 undergoes elastic torsional deformation by an amount that
corresponds to the size of the torque.
[0117] The rotary-shaft unit 6 is supported so as to be able to
freely rotate with respect to a housing (transmission case) that is
not illustrated in the figures by a pair of conical roller bearings
29a, 29b that are arranged such that the contact angles are
opposite each other. In this example, in order to install these
conical roller bearings 29a, 29b in the rotary-shaft unit 6, an
inner ring 30a of one of the conical roller bearings 29a is fitted
around a portion near one end of the input shaft 13. Moreover, a
spacer 31 is held between the end surface on the large-diameter
side of the inner ring 30a and the side surface of the one end side
of the input gear 7. Furthermore, the inner ring 30a and the input
gear 7 are joined and fastened to the input shaft 13 by pressing
the end surface on the small-diameter side of the inner ring 30
with a nut 32a that is tightly screwed onto and fastened to the one
end section of the outer-circumferential surface of the input shaft
13. On the other hand, an inner ring 30b of the other conical
roller bearing 29b is fitted around the outside of a portion near
the other end of the output shaft 14. Moreover, the end surface on
the large-diameter side of the inner ring 30b is brought into
contact with a stepped surface 33 that is formed on a portion near
the other end of the output shaft 14. Furthermore, the inner ring
30b is fastened to and supported by the output shaft 14 by pressing
the end surface on the small-diameter side of the inner ring 30b
with a nut 32b that is tightly screwed onto and fastened to the
other end section of the outer-circumferential surface of the
output shaft 14.
[0118] In this example, the direction of inclination of the teeth
of the input gear 7 and output gear 8, which are both helical
gears, is regulated so that when these gears 7, 8 are rotating in
the forward direction (when the rotary-shaft unit 6 is rotating in
the forward direction), the gear reaction forces in the axial
direction that act on these gears 7, 8 are in directions toward
each other (press against each other). As a result, when these
gears 7, 8 are rotating in the forward direction, the gear reaction
forces in that axial direction that act on the input gear 7 and
output gear 8 are able to at least partially cancel each other out.
With this kind of construction, the axial loads that are applied to
the conical roller bearings 29a, 29b when these gears 7, 8 are
rotating in the forward direction are suppressed, and the friction
loss (dynamic torque) of these bearings 29a, 29b is suppressed by
that amount.
[0119] The coupling shaft 9 is concentrically arranged on the
inner-diameter side of the torsion bar 15. When one end section of
the coupling shaft 9 is connected to the input shaft 13 so that
relative rotation is not possible, the other end section of the
coupling shaft 9 protrudes from an opening on the other end side of
the output shaft 14. In order to connect the one end section of the
coupling shaft 9 to the input shaft 13 so that relative rotation is
not possible, an outward-facing flange-shaped rim section 34 is
formed around a portion of the outer-circumferential surface of the
one end section of the coupling shaft 9 that protrudes from the
opening on the one end side of the torsion bar 15, and by forming
an involute spline connection 24d between the outer-circumferential
surface of the rim section 34 and the inner-circumferential surface
of the input shaft 13, the rim section 34 and the input shaft 13
fit together so that relative rotation is not possible. For this
connection, it is also possible to use other construction for
preventing rotation such as a key connection. Furthermore, by
holding the rim section 34 on both sides in the axial direction
using the retaining ring 25a that is fastened around the
inner-circumferential surface of the one end section of the input
shaft 13 and another retaining ring 25c, the coupling shaft 9 is
prevented from displacement in the axial direction. The first male
involute spline section 62 of the involute spline connection 24a
that is provided on the one end section of the torsion bar 15, and
a male involute spline section of an involute spline connection 24d
that is provided on the rim section 34 of the coupling shaft 9 are
provided so as to be connected together on the one end section of
the inner-circumferential surface of the input shaft 13, and the
specifications of each are the same. In other words, the involute
spline connections 24a, 24d share the first involute spline section
63 that is provided around the inner-circumferential surface of the
one end section of the input shaft 13 as the female involute spline
sections of these involute spline connections 24a, 24d.
[0120] The first encoder 10 is concentrically fastened around the
outside of the other end section of the coupling shaft 9. In other
words, the first encoder 10 is fastened to and supported by the
input shaft 13 via the coupling shaft 9. Therefore, the first
encoder 10 is able to rotate in synchronization with the input
shaft 13. Moreover, the second encoder 11 is concentrically
fastened around the outside of the other end section of the output
shaft 14. Therefore, the second encoder 11 is able to rotate in
synchronization with the output shaft 14. The first encoder 10
includes a circular ring-shaped metal core 35 that is made of a
magnetic metal and that is fastened around the outside of the other
end section of the coupling shaft 9, and a cylindrical permanent
magnet 37 that is fastened around the outer-circumferential surface
of a cylindrical section that is located on the
outer-circumferential section of the metal core 35. The second
encoder 11 also includes a circular ring-shaped metal core 36 that
is made of a magnetic metal and that is fastened around the outside
of the other end section of the output shaft 14, and a cylindrical
permanent magnet 38 that is fastened around the
outer-circumferential surface of a cylindrical section that is
located on the outer-circumferential section of the metal core
36.
[0121] The outer-circumferential surface of the permanent magnet 37
of the first encoder 10 functions as a first detected section 39,
and the outer-circumferential surface of the permanent magnet 38 of
the second encoder 11 functions as a second detected section 40.
The first and second detected sections 39, 40 have the same
diameter as each other, are concentric with each other, and are
arranged so as to be closely adjacent to each other in the axial
direction; for example, are separated in the axial direction by 10
mm or less, and preferably 5 mm or less. Moreover, as illustrated
in FIG. 9, the S poles and N poles of the detected sections 39, 40
are arranged on these detected sections 39, 40 so as to alternate
at a uniform pitch in the circumferential direction. The total
number of magnetic poles (S poles and N poles) is the same for both
of these detected sections 39, 40. In this example, when torque is
not being transmitted, or in other words, when the torsion bar 15
is not in a state of elastic torsional deformation, the detected
sections 39, 40 have not rotated relative to each other in the
direction of rotation, and the phases in the circumferential
direction of the magnetic poles of the detected sections 39, 40
coincide with each other. In other words, the poles are arranged so
that poles of these detected sections 39, 40 that are the same as
each other are adjacent to each other in the axial direction. In
this example, the fitted section where the inner-circumferential
surface of the metal core 35 of the first encoder 10 fits with the
outer-circumferential surface of the other end section of the
coupling shaft 9 is formed by arranging a cylindrical fitting
section 26b for maintaining concentricity, and an involute spline
connection 24e for preventing relative rotation so as to be
adjacent in the axial direction. Furthermore, the metal core 35 is
prevented from coming out by a retaining ring 25d that is fastened
around the outer-circumferential surface of the other end section
of the coupling shaft 9. On the other hand, the metal core 36 of
the second encoder 11 is fastened around the outside of the other
end section of the output shaft 14 by an interference fit.
[0122] The sensor unit 12 includes a holder 41 made of a synthetic
resin, and a first sensor 42a and second sensor 42b that are
embedded in the tip-end section of the holder 41. A magnetic
detecting element such as a Hall element, Hall IC, MR element, GNR
element or the like is embedded in the detecting sections of the
first and second sensors 42a, 42b. The sensor unit 12 is supported
by a housing so that the detecting section of the first sensor 42a
closely faces the first detected section 39, and the detecting
section of the second sensor 42b closely faces the second detected
section 40. In this example, as illustrated in FIG. 10, the first
and second sensors 42a, 42b are arranged in opposite directions,
and the detecting sections of the first and second sensors 42a, 42b
face the same position in the circumferential direction of detected
sections 39, 40. As a result, when the transmitted torque is in a
rotated state of zero, the phase difference between the output
signals of the sensors 42a, 42b is 180 degrees (the phase
difference ratio is 0.5).
[0123] Moreover, in this example, an oil inlet passage 43 that is
open on only the one end surface of the coupling shaft 9 is
provided in the center section in the radial direction of the
coupling shaft 9. Furthermore, oil passages 44a, 44b are provided
in portions near both ends of the coupling shaft 9, torsion bar 15,
input shaft 15 and output shaft 14. These oil passages 44a, 44b
connect the portions near both ends of the oil inlet passage 43
with minute ring-shaped spaces 45a, 45b that are located on the
inner-diameter side of the small-diameter end sections of the inner
rings 30a, 30b of the conical roller bearings 29a, 29b.
Furthermore, oil grooves 46a, 46b that extend in the radial
direction are formed at one location or plural locations in the
circumferential direction of the tip-end surfaces of the nuts 32a,
32b. With this kind of construction, lubrication oil that is
introduced from the opening on the one end section of the oil inlet
passage 43 can pass through the oil passages 44a, 44b, ring-shaped
spaces 45a, 45b and oil grooves 46a, 46b and be supplied to the
inside of the conical roller bearings 29a, 29b.
[0124] In this example, part of the lubrication oil that is fed
into the oil passages 44a, 44b passes from the middle sections of
these oil passages 44a, 44b through spaces that exist in the
involute spline connections 24a, 24b, and then fed to the
outer-circumferential surface of the middle section of the torsion
bar 15 and to the inside of a cylindrical space 47 that exists
between the inner-circumferential surfaces of the middle sections
of input shaft 13 and output shaft 14. Then, the lubrication oil
that is fed inside the cylindrical space 47 passes through the
space that exists between the tip-end surface 48 of the input-side
combination cylindrical section 16 and a stepped surface 49 that
exists at the base-end section of the inner-circumferential surface
of the output-side combination cylindrical section 17, and is
supplied to the area where the radial needle bearing 18 is
installed and the area where the thrust washer 21 is held so as to
lubricate these portions. The lubrication oil that reaches the area
where the thrust washer 21 is held provides lubrication to this
area where the thrust washer 21 is held, and also smoothly passes
through this area where the thrust washer 21 is held by passing
through the plural slits 22 that are provided in the thrust waster
21. As a result, the supply of lubrication oil to the area where
the radial needle bearing 18 is installed and the area where the
thrust washer 21 is held is performed efficiently, and the
lubricated state of the area where the radial needle bearing 18 is
installed and the area where the thrust washer 21 is held becomes
good.
[0125] Instead of the thrust washer 21 that is illustrated in FIG.
11A, it is also possible to use a thrust washer 21a such as
illustrated in FIG. 11B in which the reinforcing cylindrical
section on the outer circumference is omitted, or a simple circular
disk-shaped thrust washer 21 such as illustrated in FIG. 11C in
which the reinforcing cylindrical section on the outer
circumference and the plural slits are omitted. However, as
explained above, from the aspect of improving the lubricated state
of the area where the radial needle bearing is installed and the
area where the thrust washer is held, preferably a thrust washer
21, 21a having slits 22 such as illustrated in FIG. 11A and FIG.
11B is preferred, and furthermore, from the aspect of maintaining
the strength of the outer-circumferential section of the thrust
washer (particularly the peripheral edge of the slits 22), using a
thrust washer 21 having a reinforcing cylindrical section 23 as
illustrated in FIG. 11A is preferred.
[0126] In this example, lubrication oil is also fed from the center
section of the oil passages 44a, 44b into the inside of a minute
space that exists between the inner-circumferential surface of the
torsion bar 15 and the outer-circumferential surface of the
coupling shaft 9 (cylindrical space having a thickness in the
radial direction of about 0.2 mm). In order that feeding
lubrication oil to the inside of this kind of minute space is
performed smoothly, concave grooves 66a, 66b are provided around
the entire circumference of the portion of the
outer-circumferential surface of the coupling shaft 9 that is
aligned in the axial direction with the oil passages 44a, 44b.
During operation, the lubrication oil that is filled into a minute
space that exists between the inner-circumferential surface of the
torsion bar 15 and the outer-circumferential surface of the
coupling shaft 9 functions as a film damper that dampens small
vibration of the coupling shaft 9.
[0127] In the case of the rotation transmission device with a
torque measurement device of this example, the output signals from
the first and second sensors 42a, 42b of the sensor unit 12 change
periodically as the first and second encoders 10, 11 rotate
together with the input shaft 13 and output shaft 14 of the
rotary-shaft unit 6. Here, the frequency and period of this change
are values that correspond to the rotational speed of the
rotary-shaft unit 6. Therefore, by investigating beforehand the
relationship between the frequency or period of the output signal
from the first and second sensors 42a, 42b and the rotational
speed, it is possible to find the rotational speed based on the
frequency or period of these output signals. Moreover, in this
example, when the rotary-shaft unit 6 transmits torque between the
input gear 7 and output gear 8, the input gear 7 (input shaft 13,
first encoder 10) and the output gear 8 (output shaft 14, second
encoder 11) undergo relative displacement in the direction of
rotation as the middle section in the axial direction of the
torsion bar 15 undergoes elastic torsional deformation. As a result
of the relative displacement in the direction of rotation of the
first and second encoders 10, 11, the phase difference ratio
(=phase difference/1 period) between the output signals from the
first and second sensors 42a, 42b changes. Here, this phase
difference ratio is a value that corresponds to the torque that is
transmitted by the rotation transmission device. Therefore, by
investigating beforehand the relationship between the phase
difference ratio of the output signals from the first and second
sensors 42a, 42b and the torque of the rotation transmission
device, it is possible to find the torque that is transmitted by
the rotation transmission device based on this phase difference
ratio.
[0128] In this example, the shaft is divided into two, an input
shaft 13 and an output shaft 14; the input gear 7 is fastened
around the middle section in the axial direction of the
outer-circumferential surface of the input shaft 13, and the output
gear 8 is fastened around the middle section in the axial direction
of the outer-circumferential surface of the output shaft 14; and
both the input shaft 13 and output shaft 14 have hollow
construction. Moreover, a torsion bar 15 that is connected to the
input shaft 13 and the output shaft 14 so that both end sections
are not capable of relative rotation is arranged on the
inner-diameter side of the input shaft 13 and output shaft 14, and
furthermore, a coupling shaft 9 that supports a first encoder 10 on
the other end section is arranged on the inner-diameter side of the
torsion bar 15. In other words, the rotation transmission device
with a torque measurement device has a triple structure that
includes an input shaft 13 and output shaft 14, a torsion bar 15
and a coupling shaft 9. In the case of the rotation transmission
device of this example having this kind of construction, torque
that is inputted from the input gear 7 is transmitted to the output
gear 8 along a path such as illustrated by the arrow in FIG. 12
(input gear 7.fwdarw.involute spline connection 24c.fwdarw.input
shaft 13.fwdarw.involute spline connection 24a.fwdarw.torsion bar
15.fwdarw.involute spline connection 24b.fwdarw.output shaft
14.fwdarw.output gear 8).
[0129] Therefore, in this example, the dimension L in the axial
direction of the middle section in the axial direction of the
torsion bar 15 is sufficiently longer than the space W between the
input gear 7 and the output gear 8 (L>W). Therefore, it is
possible to sufficiently maintain the amount of elastic torsional
deformation of the middle section in the axial direction of the
torsion bar 15 that occurs when transmitting torque. As a result,
differing from construction in which the rotary-shaft unit 6 has
only a single rotary shaft, it is possible to sufficiently increase
the resolution of torque measurement by sufficiently increasing the
amount of relative displacement in the direction of rotation
between the input gear 7 (input shaft 13, first encoder 10) and the
output gear 8 (output shaft 14, second encoder 11) that occurs
during the transmission of torque regardless of whether the space W
in the axial direction between the input gear 7 and the output gear
8 is large or small. Moreover, in this example, by adjusting the
dimension in the radial direction and dimension in the axial
direction of the middle section in the axial direction of the
torsion bar 15 during the design stage, it is possible to easily
adjust the torsional rigidity of this middle section in the axial
direction. Therefore, when compared with construction in which the
rotary-shaft unit 6 has only a single rotary shaft, the
relationship between the torque that is transmitted by the rotation
transmission device and the amount of relative displacement in the
direction of rotation of the first and second encoders 10, 11
(gain) can be easily designed to obtain a desired value.
[0130] Moreover, in this example, the sensor unit 12 is a single
unit, so it is possible to run only one harness (not illustrated in
the figures) from the sensor unit 12, so it is possible to easily
install the required harness. In addition, only one area inside the
housing is needed for supporting and fastening the sensor unit 12,
so processing of the housing is simplified.
[0131] Furthermore, in this example, when transmitting torque, it
is possible to maintain the precision of torque measurement by the
sensor unit 12 regardless of deformation (elastic deformation) of
the housing due to gear reaction forces in the radial direction
that act on the input gear 7 and output gear 8. In other words, in
this example, the first and second encoders 10, 11 are arranged so
as to be concentrated on the other end side of the output shaft 14,
so the sensor unit 12 can be supported by a portion of the housing
that is near the end section with high rigidity. Therefore, even
when the housing is deformed due to gear reaction forces, contact
between the sensor unit 12 and the first and second encoders 10, 11
is prevented. Consequently, it is possible to reduce the space
between the first detected section 39 of the first encoder 10 and
the detected section 40 of the second encoder 11, and to improve
the precision of torque measurement.
[0132] Moreover, in this example, when transmitting torque, it is
possible to prevent stress that is due to gear reaction forces in
the radial direction that act on the input gear 7 and output gear 8
from becoming concentrated in the torsion bar 15. In other words,
the rotary-shaft unit 6 is constructed by combining an input-side
combination cylindrical section 16 of the input shaft 13 and an
output-side combination cylindrical section 17 of the output shaft
14 together by way of a radial needle bearing 18 and a thrust
washer 21, so gear reaction forces are mainly applied to the
connection between the input-side combination cylindrical section
16 and the output-side combination cylindrical section 17, and
supported by the radial needle bearing 18 and thrust washer 21. As
a result, the gear reaction forces are prevented from becoming
concentrated in the torsion bar 15.
[0133] In the rotation transmission device of this example, it is
also possible to use construction in which the direction that the
detected sections of the first and second encoders face the
detecting sections of the pair of sensors of the sensor unit is
changed from the radial direction to the axial direction. In that
case, the detected sections of the first and second encoders are a
pair of circular disk-shaped detected sections having radial
dimensions that differ from each other, and these detected sections
are arranged so as to be concentric with each other when facing in
the same axial direction (overlap in the radial direction), and the
detecting sections of the pair of sensors of the sensor unit that
are arranged so as to be separated in the radial direction of the
rotary-shaft unit are made to face these detected sections in the
axial direction.
Second Example
[0134] FIG. 13 and FIG. 14 illustrate a second example of an
embodiment of the present invention. In this example, when torque
is not being transmitted, the phases in the circumferential
direction of the magnetic poles of the detected sections 39, 40 of
the first and second encoders 10, 11 are shifted 180 degrees from
each other. In other words, poles of these detected sections 39, 40
that are different from each other are arranged so as to be
adjacent to each other in the axial direction. Moreover, when the
pair of sensors 42a, 42b of the sensor unit 12 are arranged so that
each faces in the same direction, the detecting sections of these
sensors 42a, 42b face the same position in the circumferential
direction of the detected sections 39, 40. As a result, when the
transmitted torque is in a rotated state of zero, the phase
difference between the output signals of the sensors 42a, 42b is
180 degrees (the phase difference ratio is 0.5).
[0135] In this example, in the state before installing the first
and second encoders 10, 11 in the locations where the encoders 10,
11 will be used, and the end surfaces in the axial direction of the
permanent magnets 37, 38 of these encoders 10, 11 that face each
other are magnetically stuck together, and as a result, the phase
in the circumferential direction of the magnetic poles of these
encoders 10, 11 are shifted 180 degrees from each other. By
installing these encoders 10, 11 in this state, a positional
arrangement of the magnetic poles after installation such as
illustrated in FIG. 13 is easily achieved. The other construction
and functions are the same as in the first example of an
embodiment.
Third Example
[0136] FIG. 15A, FIG. 15B and FIG. 16 illustrate a third example of
an embodiment of the present invention. In this example, as
illustrated in FIG. 15A, two through holes 67a, 67b, which are both
regulating parts, are provided in the metal core 35b of the first
encoder 10f and are separated in the circumferential direction.
Moreover, as illustrated in FIG. 15B, one concave hole 68, which is
a regulating part, is provided in the metal core 36b of the second
encoder 11f. When the center axes of these encoders 10f, 11f
coincide with each other, the positions in the radial direction of
the through holes 67a, 67b and the convex hole 68 are the same as
each other. Moreover, the pitch of these through holes 67a, 67b
(distance in the circumferential direction between centers) is the
same as the pitch of one magnetization (distance in the
circumferential direction between centers of an S pole and N pole
that are adjacent in the circumferential direction) of the encoders
10f, 11f.
[0137] In this example, when magnetizing the encoders 10f, 11f in
the manufacturing stage, the center axes of these encoders 10f, 11f
are made to coincide with each other, and a pin 69 is passed
through or inserted into one of the through holes 67a, 67b and into
the concave hole 68 as a regulating member so that there is no
looseness. As a result the encoders 10f, 11f can be positioned in
the circumferential direction. In this state, S poles and N poles
are simultaneously magnetized on the detected sections 39, 40 of
the encoders 10f, 11f so that the phases in the circumferential
direction are the same as each other, and so as to alternate in the
circumferential direction at a uniform pitch.
[0138] When installing the magnetized encoders 10f, 11f in the
location of use with a positional relationship as illustrated in
FIG. 9, the pin 69 passes through one of the through holes 67a, 67b
and is inserted into the concave hole 68 positions the encoders
10f, 11f in the circumferential direction, and these encoders 10f,
11f are then installed in the location of use. On the other hand,
when installing the encoders 10f, 11f in the location of use with a
positional relationship as illustrated in FIG. 13, the through hole
of the encoder 10f though which the pin 69 is passed is changed
from the one though hole of the through holes 67a, 67b to the other
through hole, and then with the relative positional relation in the
circumferential direction of the encoders 10f, 11f shifted an
amount of the pitch of one magnetization from the positional
relationship at the time of magnetization, the encoders 10f, 11f
are installed and fastened in the location of use, after which the
pin 69 is removed from the through hole 67a or 67b and the concave
hole 68.
[0139] By installing the encoders 10f, 11f in this way, the work of
installing these encoders 10f, 11f in the location of use can be
performed easily and accurately. Instead of the concave hole 68, it
is possible to provide a through hole through which the pin 69 can
be passed though with no looseness. The other construction and
functions are the same as those of the first and second examples of
embodiments.
Fourth Example
[0140] FIG. 17A and FIG. 17B illustrate a fourth example of an
embodiment of the present invention. In this example, a pair of
concave sections 70a, 70b, which are regulating sections, are
provided in one end surface in the axial direction (the end surface
on the second encoder 11g side) of the permanent magnet 37b of the
first encoder 10g so as to be separated in the circumferential
direction. Moreover, one convex section 71, which is a regulating
section, is provided on one end surface in the axial direction (end
surface on the first encoder 10g side) of the permanent magnet 38b
of the second encoder 11g. The pitch of the concave sections 70a,
70b is equal to the pitch of one magnetization of the encoders 10g,
11g.
[0141] In this example, when magnetizing the encoders 10g, 11g in
the manufacturing stage, the ends in the axial direction of the
permanent magnets 37b, 38b of the encoders 10g, 11g are placed
against each other, and by fitting one of the concave sections 70a,
70b with the convex section 71, the encoders 10g, 11g are
positioned in the circumferential direction. In this state, the
detected sections 39, 40 of the encoders 10g, 11g are
simultaneously magnetized so that the S poles and N poles are in
the same phase in the circumferential direction, and so as to
alternate at a uniform pitch in the circumferential direction.
[0142] When installing the encoders 10g, 11g in the location of use
with a positional relationship such as illustrated in FIG. 9, one
of the concave sections 70a, 70b is fitted with the convex section
71, which positions the encoders 10g, 11g in the circumferential
direction, and then the encoders 10g, 11g are installed in the
location of use. On the other hand, when installing the encoders
10g, 11g in the location of use with a positional relationship such
as illustrated in FIG. 13, one of the end surfaces in the axial
direction of the permanent magnets 37b, 38b of the encoders 10g,
11g are placed together, and by fitting the other concave section
of the concave sections 70a, 70b with the convex section 71 as
illustrated in FIG. 17B, the encoders 10g, 11g are positioned in
the circumferential direction, and then the encoders 10g, 11g are
installed in the location of use. As a result, the work of
installing the encoders 10g, 11g in the location of use can be
performed easily and accurately. The other construction and
functions are the same as in the first and second examples of
embodiments.
Fifth Example
[0143] FIG. 18 illustrates a fifth example of an embodiment of the
present invention. In this example, a pair of markings 72a, 72b,
73a, 73b such as concave sections or convex sections, which are
regulating sections, are provided on the other end surface in the
axial direction (end surface on the side opposite from the second
encoder 11h) of the permanent magnet of the first encoder 10h, and
on the one end surface in the axial direction (end surface on the
first encoder 10h side) so as to be separated in the
circumferential direction. The positions in the circumferential
direction of the marking 72a, 72b that are provided on the first
encoder 10h coincide with the positions in the circumferential
direction of two magnetization boundaries (boundaries between S
pole and N pole) that are adjacent in the circumferential direction
of the detected section 39 of the first encoder 10h. Moreover, the
positions in the circumferential direction of the marking 73a, 73b
that are provided on the second encoder 11h coincide with the
positions in the circumferential direction of two magnetization
boundaries that are adjacent in the circumferential direction of
the detected section 40 of the second encoder 11h.
[0144] In this example, the work of installing the encoders 10h,
11h in the location of use is performed in the assembled state,
making sure that the positions in the circumferential direction of
both the markings 72a, 72b and the markings 73a, 73b coincide, or
so that the positions in the circumferential direction of the
marking 72a and the marking 73b (or the marking 72b and the marking
73a) coincide. As a result, the work of installing the encoders
10h, 11h in the location of use can be performed easily and
accurately. The other construction and functions are the same as
those of the first and second examples of embodiments.
Sixth Example
[0145] FIG. 19 to FIG. 21 illustrate a sixth example of an
embodiment of the present invention. In this example, a first
plating layer 74 is provided on the surface layer of a first male
involute spline section 62a that is provided on the
outer-circumferential surface of the one end of the torsion bar
15b, and a second plating layer 75 is provided on the surface layer
of a second male involute spline section 64a that is provided on
the outer-circumferential surface of the other end section of the
torsion bar 15b. The first and second plating layers 74, 75 are
formed using a metal such as copper or nickel that are softer than
the steel alloy such as carbon steel of the torsion bar 15, input
shaft 13 and output shaft 14 (see FIG. 6). The first male involute
spline section 62a (second male involute spline section 64a) is
press fitted into a first female involute spline section 63a that
is provided on the inner-circumferential surface of the input shaft
13 (second female involute spline section 65a that is provided on
the inner-circumferential surface of the output shaft 14) so that
the interference is less than the thickness dimension in the free
state of first plating layer 74 (second plating layer 75). As a
result, an involute spline connection 24a1 (involute spline
connection 24b1) can be formed by fitting the first male involute
spline section 62a (second male involute spline section 64a) with
the first female involute spline section 63a (second female
involute spline section 65a) so that there is no looseness in the
circumferential direction. In this example, by the first plating
layer 74 (second plating layer 75) being crushed between the teeth
surfaces of the first male involute spline section 62a (second male
involute spline section 64a) and the first female involute spline
section 63a (second female involute spline section 65a), a function
of eliminating looseness in the in the circumferential direction of
the involute spline connection 24a1 (involute spline connection
24b1) is achieved. On the other hand, a space remains between the
tip of the tooth and bottom of the tooth of the first male involute
spline section 62a (second male involute spline section 64a) and
the first female involute spline section 63a (second female
involute spline section 65a), and these spaces function as passages
for lubrication oil.
[0146] In this example, in order to set the interference described
above, the thickness dimension T in the free state of the first
plating layer 74 (second plating layer 75) is greater than the
space t between the teeth surfaces in the state before forming the
first plating layer 74 (second plating layer 75) on the first male
involute spline section 62a (second male involute spline section
64a) illustrated in FIG. 20 (T>t). In the state illustrated in
FIG. 20, this space t can be found as t=dsin .theta. (.theta.:
angle of the tooth surface with respect to the radial line that is
set in the design) based on the measurement of 2d, which is the
amount that the first male involute spline section 62a (second male
involute spline section 64a) and first female involute spline
section 63a (second female involute spline section 65) can move
relative to each other in the radial direction. This space t can
also be found by measurement using a conventionally known
measurement pin or by using some other method.
[0147] In this example as well, the involute spline connections
24a1, 24b1 are connections in which there is no looseness in the
circumferential direction. Therefore, when the direction of
rotation of the input shaft 3, which is the rotary shaft on the
side where torque is inputted, rotates in the reverse direction, it
is possible to prevent relative rotation in the space in the
circumferential direction in the involute spline connections 24a1,
24b1 that is the cause of looseness. In other words, when the
direction of rotation of the input shaft 13 is in the reverse
direction and relative rotation occurs in the involute spline
connections 24a1, 24b1 in the spaces in the circumferential
direction, relative rotation also occurs between the first and
second encoders 10, 11. As a result, as illustrated by the dashed
line .beta. in FIG. 21, the characteristic curve that expresses the
relationship between the sensor output and the torque suddenly
changes and is non-linear when the torque=0 and near 0, so it
becomes difficult to accurately measure minute torque. On the other
hand, in this example, when the direction of rotation of the input
shaft 13 is reversed, the occurrence of relative rotation in the
spaces in the involute spline connections 24a1, 24b1 that are the
cause of looseness is prevented. The occurrence of relative
rotation between the first and second encoders 10, 11 is also
prevented. As a result, as illustrated by the solid line a in FIG.
21, linearity of the characteristic curve that expresses the
relationship between the sensor output and the torque is maintained
overall, and so it is possible to accurately measure minute
torque.
[0148] In this example, when press fitting the first and second
male involute spline sections 62a, 64a into the first and second
female involute spline sections 63a, 65a, a large portion of the
deformation (elastic deformation or plastic deformation) of the
interference area occurs in the first and second plating layers 74,
75 that are relatively soft. Therefore, the spaces in the
circumferential direction that are the cause of looseness in the
involute spline connections 24a1, 24b1 can be effectively filled in
by the first and second plating layers 74, 75. Moreover,
deformation of the copper or nickel of the first and second plating
layers 74, 75 occurs at a smaller force than the deformation of the
steel of the main portion of the involute spline sections 62a, 64a,
63a, 65a, so it is possible to keep the force required for
performing a press fit low. Moreover, in this example, metal such
as copper, nickel or the like that has suitable crushing
characteristics and rigidity is used as the metal of the first and
second plating layers 74, 75, so even when used over a long period
of time, it is possible to make it difficult for spaces to occur
between the plating layers 74, 75 and the teeth surfaces of the
female involute spline sections 63a, 65a. In addition to the
involute spline connections 24a1, 24b1, it is also possible to
apply construction for eliminating looseness in the circumferential
direction by using a suitable and relatively soft plating layer in
the involute spline connections 24c to 24e (se FIG. 6). Moreover,
in applications in which it is not necessary to measure minute
torque, it is also possible to use connections having a little
looseness in the circumferential direction for any of the involute
spline connections 24a to 24e (see FIG. 6) without applying the
construction of this example, and that construction is also within
the scope of the present invention. The other construction and
functions are the same as those of the first through fifth examples
of embodiments.
Seventh Example
[0149] FIG. 22 and FIG. 23 illustrate a seventh example of an
embodiment of the present invention. In this example, a rim section
34a that is provided on one end section of the coupling shaft 9b is
fastened around the inside of the one end section of the input
shaft 13a with an interference fit. More specifically, the
outer-circumferential surface of the rim section 34a is taken to be
a cylindrical surface 76, and that cylindrical surface 76 is fitted
around a cylindrical surface 77 that is provided on the
inner-circumferential surface of the other end section of the input
shaft 13a with an interference fit. With this kind of construction,
it is possible to simplify the construction of the portion where
the one end section of the coupling shaft 9b is connected to the
input shaft 13a so that relative rotation is not possible, and thus
manufacturing cost can be suppressed by that amount. The other
construction and functions are the same as those of the first
through sixth examples of embodiments.
Eighth Example
[0150] FIG. 24 illustrates an eighth example of an embodiment of
the present invention. In this example, of the pair of conical
roller bearings 29c, 29d that support the rotary-shaft unit 6b so
as to be able to freely rotate with respect to the housing, the
inner ring 30c of one of the conical roller bearings 29c is made so
as to be integrated with the input shaft 13b, and the inner ring
30d of the other conical roller bearing 29d is made so as to be
integrated with the output shaft 14a. As a result, the nuts 32a,
32b for preventing the inner rings 30c, 30d from coming out (see
FIG. 6) are eliminated. Moreover, the dimension of the inner
diameter of the input gear 7 that is fastened around the outside of
the input shaft 13b is made to be larger than the dimension of the
outer diameter of the inner ring 30c. As a result, when installing
the input gear 7 onto or removing the input gear 7 from the input
shaft 13b, the input gear 7 can pass in the axial direction over
the inner ring 30c. In this example, separate inner rings 30c, 30d,
and nuts 32a, 32b are eliminated, so it is possible to reduce the
number of parts and assembly steps, simplify construction, make
construction more compact and lightweight, and reduce manufacturing
costs, and it is possible to improve the strength of the rim
sections of the inner rings 30c, 30d, and improve the freedom of
placement of the conical roller bearings 29c, 29d. The other
construction and functions are the same as those of the first
through seventh examples of embodiments.
Ninth Example
[0151] FIG. 25 to FIG. 29 illustrate a ninth example of an
embodiment of the present invention. In this example, the first
encoder 10a that is fastened around the outside of the other end
section of the coupling shaft 9 is formed into a complete ring
shape having an L-shaped cross section using a magnetic metal, and
the outer circumference of the first encoder 10a functions as a
flat gear shaped first detected section 39a. In other words, the
first detected section 39a is constructed so that plural convex
sections 50 that protrude to the outer-diameter side from the
portion near the outer circumference of the first encoder 10a are
arranged at a uniform pitch in the circumferential direction. In
this example, of the first detected section 39a, the convex
sections correspond to solid sections, and portions between convex
sections 50 that are adjacent in the circumferential direction
correspond to sections where material has been removed.
[0152] Moreover, the second encoder 11a that is fastened around the
outside of the other end section of the output shaft 14 is formed
into a complete cylindrical shape using magnetic metal plate, and
the tip half section that protrudes in the axial direction from the
other end surface of the output shaft 14 functions as a comb shaped
second detected section 40a. In other words, the second detected
section 40a is constructed so that plural tongue pieces 51 that
extend in the axial direction toward the tip end side from the
middle section in the axial direction of the second encoder 11a are
arranged at a uniform pitch in the circumferential direction. The
total number of these tongue pieces 51 is the same as the total
number of convex section 50. Moreover, the width in the
circumferential direction that is expressed by the center angle of
these tongue pieces 51 is equal to the width in the circumferential
direction that is expressed by the center angle of the convex
sections 50. In this example, of the second detection section, the
tongue pieces 51 correspond to solid sections, and the spaces
between tongue pieces that are adjacent in the circumferential
direction correspond to sections with material removed.
[0153] In this example, with the inner-circumferential surface of
the second detected section 40a closely facing the
outer-circumferential surface of the first detected section 39a,
the first and second detected sections 39a, 40a are arranged so as
to be concentric with each other, or in other words, so as to
overlap in the radial direction. Moreover, when torque is not being
transmitted, or in other words, when the torsion bar 15 has not
undergone elastic torsional deformation, and the detected sections
39a, 40a have not undergone relative displacement in the direction
of rotation, the phases in the circumferential direction of the
convex sections 50 and the tongue pieces 51 coincide with each
other.
[0154] Furthermore, the sensor unit 12a is formed into a complete
circular ring shape, and concentrically arranged around the
outer-diameter side of the first and second detected sections 39a,
40a. The sensor unit 12a includes a stator 52 made of a magnetic
material, and plural coils 54 that are formed using one conducting
wire 53. The stator 52 includes plural core sections 55 that are
long in the radial direction, and a circular ring-shaped rim
section 56 that connects the base-end sections, on the
outer-diameter side of the core sections 55. The total number of
core sections 55 is the same as the total number of convex sections
50 and tongue pieces 51. Moreover, the width in the circumferential
direction that is expressed by the center angle of the tip-end
surfaces on the inner-diameter side of the core sections 55 is
equal to the width in the circumferential direction of the tongue
pieces 51 (width in the circumferential direction of the convex
sections 50). In this example, the end surfaces on the
inner-diameter side of such core sections 55 are made to closely
face the outer-circumferential surface of the second detected
section 40a. Moreover, the coils 54, together with being wound
around the core sections 55, are such that the winding directions
of coils that are adjacent to each other in the circumferential
direction are opposite each other. Therefore, in this example, the
total number of coils 54 is an even number (10 coils 54 in the
example in the figures), and the total number of convex sections 50
and tongue pieces is also an even number.
[0155] In this example, the coils 54 have both a driving function
for generating a magnetic field, and a detection function for
detecting change in the magnetic field. In other words, by applying
a driving voltage to the coils 54 (conducting wire 53), a driving
current flows through these coils 54, and between coils 54 that are
adjacent in the circumferential direction, a loop-shaped magnetic
fluxes such as illustrated by the bold arrow lines in FIG. 27 flow
inside the stator 52 and first and second encoders 10a, 11a. In
this state, when the first and second encoders 10a, 11a rotate
together with the rotary-shaft unit 6, the density of the
loop-shaped magnetic flux periodically changes, and as this occurs,
a periodic induced current flows in the coils 54. As a result, the
output of the conducting wire 53, which is the output of the sensor
unit 12a, and more specifically, the voltage and current (when the
driving voltage is an alternating-current voltage, the peak values
or effective values of these) periodically change as illustrated in
FIG. 29C. Here, the frequency (and period) of this output is a
value that corresponds to the rotational speed of the rotary-shaft
unit 6. Therefore, by investigating the relationship between the
frequency (or period) of this output and the rotational speed, it
is possible to find the rotational speed based on this frequency
(or period).
[0156] In this example, when torque is being transmitted, the
encoders 10a, 11a displace relative to each other in the direction
of rotation due to elastic torsional deformation of the torsion bar
15, and as a result, the phase in the circumferential direction of
the convex sections 50 and the tongue pieces 51 of the detected
sections 39a, 40a shift in the order as illustrated from FIG. 29A
to FIG. 29B. As this occurs, the widths in the circumferential
direction of the magnetic paths inside the encoders 10a, 11a, which
are the portions where the convex sections 50 overlap the tongue
pieces in the radial direction, decreases. As a result, the size of
the output of the conducting wire 53 decreases in the order as
illustrated from the dashed line to the solid line in FIG. 29C.
Here, the shift in phase (the amount of decrease in the width in
the circumferential direction of the magnetic path) becomes larger
the larger the torque becomes. Therefore, the size of the output
decreases more the larger the torque becomes. However, the size of
the output not only changes due to the torque, but also changes due
to the rotational speed. In other words, the size of the induced
current that flows in the coils 54 (induced electromotive force in
the coils 54) is proportional to the rate of change in the magnetic
flux that passes through the coils 54. The rate of change of this
magnetic flux becomes large in proportion to the rotational speed.
Therefore, the size (amplitude) of the output becomes larger in
proportion to the rotational speed. In this example, the effect
that the torque has on the size of the output, and the effect that
the rotational speed has on the size of the output are both
investigated beforehand. As described above, the rotational speed
is found based on the frequency (or period) of the output, and
correction is performed to return the size of the output that has
changed due to the effect of the rotational speed to the original
size. By doing so, it is possible to accurately find the torque
based on the size of the output after this correction. The driving
voltage that is applied to the conducting wire 53 can also be a
direct-current voltage, however, in order to increase the
resistance to noise, an alternating-current voltage is
preferred.
[0157] In this example, the sensor unit 12a is combined with the
stator 52 and coils 54 and does not include precision electronic
parts such as a magnetism-detecting device, so has excellent heat
resistance and vibration resistance. Moreover, in this example,
there is only one output that is used for measuring the rotational
speed and the torque, so there is no need for complex signal
processing when performing measurement. Consequently, it is
possible to use an inexpensive computing device that does not have
very high processing capability as the computing device used in
performing this signal processing.
[0158] It is also possible to use construction wherein the
direction in which the detected sections of the first and second
encoders face the tip-end surfaces of the core sections of the
sensor unit can be changed from the radial direction to the axial
direction. In that case, the detected sections of the first and
second encoders are a pair of circular disk-shaped detected
sections having the same dimensions in the radial direction, and
these detected sections are arranged so as to overlap in the axial
direction. On the other hand, the core sections of the sensor unit
are formed so as to be long in the axial direction. The tip-end
surfaces of these core sections can face the detected sections from
one side in the axial direction, which is the direction in which
these detected sections overlap. The other construction and
functions are the same as those of the first through eighth
examples of embodiments.
Tenth Example
[0159] FIG. 30 to FIG. 35 illustrate a tenth example of an
embodiment of the present invention. In this example, the first
encoder 10b that is fastened around the outside of the other end
section of the coupling shaft 9, and the second encoder 11b that is
fastened around the outside of the other end section of the output
shaft 14 are formed into a complete circular ring shape using a
magnet metal, and each encoder 10b, 11b includes a comb-shaped
cylindrical detection section 39b (40b). In other words, the first
detected section 39b of the first encoder 10b, and the second
detected section 40b of the second encoder 11b are formed so that
plural tongue pieces 51a (51b) that are long in the axial direction
are arranged at a uniform pitch in the circumferential direction,
and so that the base-end sections of these tongue pieces 51a (51b)
are connected together. Moreover, the shape and dimensions of the
detected sections 39b, 40b are the same as each other, however, the
direction that each faces in the axial direction is opposite of
each other. The tongue pieces 51a of the first detected section 39b
and the tongue pieces 51b of the second detected section 40b are
arranged so that when located in a space in the circumferential
direction, the tongue pieces alternate one tongue piece at a time
in the circumferential direction. In this example, when torque is
not being transmitted, the widths in the circumferential direction
of the portions between tongue pieces 51a, 51b that are adjacent in
the circumferential direction are all the same. Furthermore, the
widths in the circumferential direction of the portions between
tongue pieces 51a, 51b that are adjacent in the circumferential
direction are the same as the widths in the circumferential
direction of the tongue pieces 51a, 51b. This is so that the duty
ratios when torque is not being transmitted is 0.5. In this
example, of the detected sections 39b (40b), the tongue pieces 51a
(51b) correspond to solid sections, and the portions between tongue
pieces 51a (51b) that are adjacent in the circumferential direction
correspond to sections where material has been removed.
[0160] In this example, the sensor unit 12b includes a holder 41a
that is made of a synthetic resin, and one sensor 42c that is
embedded in the tip-end section of the holder 41a; and the
detecting section of the sensor 42c is made to closely face the
outer-circumferential surface of the detected sections 39b, 40b
(portions where the tongue pieces 51a, 51b are arranged in an
alternating manner in the circumferential direction). The sensor
42c includes a permanent magnet that is magnetized in the direction
that the outer-circumferential surfaces of the detected sections
39b, 40b face the detecting section of the sensor 42c, and a
magnetic detecting element such as Hall element, Hall IC, MR
element, GMR element and the like that is arranged on the end
surface of both end surfaces in the magnetized direction of the
permanent magnet that faces the outer-circumferential surfaces of
the detected sections 39b, 40b.
[0161] In this example, the output signal from the sensor 42c of
the sensor unit 12b periodically changes as the first and second
encoders 10b, 11b rotate together with the rotary-shaft unit 6.
Moreover, as the first and second encoders displace relative to
each other in the direction of rotation due to elastic torsional
deformation of the torsion bar 15 when torque is being transmitted
by the rotary-shaft unit 6, the widths in the circumferential
direction of the portions between tongue pieces 51a, 51b that are
adjacent in the circumferential direction change. More
specifically, the widths in the circumferential direction of every
other one of the portions between the tongue pieces 51a, 51b become
larger, and the widths in the circumferential direction of the
remaining portions become smaller. As a result, the duty ratio
.epsilon. (=time ratio B/A) of the output signal of the sensor 42c
changes as illustrated in the order from FIG. 34A to FIG. 34B.
Here, the amount that the widths in the circumferential direction
of the portions between tongue pieces 51a, 51b that become larger
(smaller) is a value that corresponds to the torque that is
transmitted by the rotation transmission device, so the duty ratio
s is also a value that corresponds to the torque. Therefore, by
investigating in advance the relationship between the duty ratio s
and the torque such as illustrated in FIG. 35, the torque can be
found based on this duty ratio .epsilon.. Furthermore, in regard to
the output signal of the sensor 42c, the 2-pulse period A is a
value that corresponds to the rotational speed of the rotary-shaft
unit 6. Therefore, by investigating the relationship between the
2-pulse period A and the rotational speed, it is possible to find
the rotational speed based on the 2-pulse period A.
[0162] In this example, the detected sections of the first and
second encoders 10b, 11b are made to overlap in the circumferential
direction, so it is possible to shorten the dimension in the axial
direction of the portions where these detected sections 39b, 40b
are located, and thus construction that conserves space by this
amount is possible. Moreover, it is sufficient to install only one
magnetism-detecting element in the sensor unit 12b, so the cost of
the sensor unit 12b can be suppressed. The other construction and
functions are the same as those of the first through eighth
examples of embodiments.
Eleventh Example
[0163] FIG. 36 to FIG. 38 illustrate an eleventh example of an
embodiment of the present invention. In this example, the first
detected section 39c of the first encoder 10c that is fastened
around the outside of the other end section of the coupling shaft
9, and the second detected section 40c of the second encoder 11c
that is fastened around the outside of the other end section of the
output shaft 14 are both formed into a comb-like circular ring
shape. Moreover, when the positions in the axial direction of these
detected sections 39c, 40c coincide with each other, the tongue
pieces 51c, 51d of the detected sections 39c, 40c are arranged in
an alternating manner in the circumferential direction when located
in a space in the circumferential direction. The detecting section
of one sensor 42c of the sensor unit 12b is made to face in the
axial direction the side surface in the axial direction of the
portion where the tongue pieces 51c, 51d are arranged.
[0164] Except for changing the shape of the detected sections 39c,
40c to a circular disk shape, and changing the direction in which
the detected sections 39c, 40c face the detecting section of the
sensor 42 to the axial direction, the other construction and
functions are the same as those of the tenth example of an
embodiment.
Twelfth Example
[0165] FIG. 39 to FIG. 42 illustrate a twelfth example of an
embodiment of the present invention. In this example, the first
encoder 10 that is fastened to and supported by the other end
section of the coupling shaft 9 includes a ring-shaped metal core
35a that is made of a magnetic material and that is fastened around
the outside of the other end section of the coupling shaft 9, and a
cylindrical-shaped permanent magnet 37a that is fastened around the
outer-circumferential surface of a cylindrical section that exists
on the outer circumference of the metal core 35a. S poles and N
poles are arranged on the first detected section 39a, which is the
outer-circumferential surface of the permanent magnet 37a, at a
uniform pitch and so as to alternate in the circumferential
direction. On the other hand, the second encoder 11d that is
fastened to and supported by the other end section of the output
shaft 14 includes a ring-shaped metal core 36a that is made of
magnetic metal sheet and that is fastened around the outside of the
other end section of the output shaft 14, and a cylindrical shaped
permanent magnet 38a that is fastened around the
inner-circumferential surface of a cylindrical section that exists
on the outer circumference of the metal core 36a. The second
detected section 40d, which is the inner-circumferential surface of
the permanent magnet 38a, is concentrically arranged on the
outer-diameter side of the first detected section 39d so that there
is a specified space in the radial direction. In other words, the
first and second detected sections 39, 40d face each other through
a specified space in the radial direction. There are also S poles
and N poles arranged on the second detected section 40d at a
uniform pitch and so as to alternate in the circumferential
direction. The total number of magnetic poles (S poles, N poles)
that are arranged on the second detected section 40d and the total
number of magnetic poles that are arranged on the first detected
section 39d are the same as each other. Moreover, when torque is
not being transmitted, the detected sections 39d, 40d are arranged
so that the centers of different poles face each other in the
radial direction.
[0166] In this example, the sensor unit 12c that is supported by
the housing (not illustrated in the figures) includes a holder 41b
made of a synthetic resin, and one sensor 42d that is embedded in
the tip-end section of the holder 41b; and the sensor 42d is
arranged so as to be in the center position in the radial direction
between the detected sections 39d, 40d. A magnetism-detecting
element such as a Hall element, Hall IC, MR element, GMR element or
the like is assembled in the detecting section of the sensor 42d,
and the sensing direction of that magnetism-detecting element is
such that the center section of the element coincides with the
radial direction of the first and second detected sections 39d,
40d. In other words, the sensing direction of this
magnetism-detecting element is in the up-down direction in FIG. 41A
and FIG. 41B, and the magnetic flux density in this up-down
direction is proportional to the size of the output (voltage,
current) of the magnetism-detecting element, which is the output
signal of the sensor unit 12c.
[0167] In the rotation transmission device of this example, when
torque is not being transmitted as illustrated in FIG. 41A, or in
other words, when there is no relative displacement in the
direction of rotation between the detected sections 39d, 40d, the
different poles of the detected sections s39d, 40d face each other
in the radial direction, so the direction of the magnetic flux that
passes through the magnetism-detecting element mostly coincides
overall with the direction of sensitivity of the detecting element.
In other words, in this state, the magnetic flux density in the
direction of sensitivity is a maximum, so the output of the
magnetism-detecting element is also a maximum. On the other hand,
when torque is being transmitted as illustrated in FIG. 41B, or in
other words, when there is relative displacement in the direction
of rotation between the detected sections 39d, 40d, the positional
relationship of different poles of the detected sections 39d, 40d
shifts in the circumferential direction, so the direction of the
magnetic flux that passes through the magnetism-detecting element
becomes inclined overall with respect to the direction of
sensitivity of the element. In other words, in this state, the
magnetic flux density decreases by the amount of this inclination,
and thus the output of the magnetism-detecting element also
decreases by that amount. Here, the size of this inclination
becomes larger the larger the torque (shift in the circumferential
direction) is. Therefore, the output of the magnetism-detecting
element becomes a maximum when torque is zero, and becomes small as
the torque becomes larger.
[0168] When torque is being transmitted, the detected sections 39d,
40d rotate together with the rotary-shaft unit 6. Therefore, the
output of the magnetism-detecting element has a sinusoidal shape as
illustrated in FIG. 42. The size (amplitude) of this output becomes
larger as the torque becomes larger. Therefore, by investigating
the relationship between the size of the output and the torque
beforehand, the torque can be found based on the size of the
output. Moreover, the frequency (and period) of the output is a
value that corresponds to the rotational speed of the rotary-shaft
unit 6. Therefore, by investigating the relationship between the
frequency (or period) and the rotational speed beforehand, it is
possible to find the rotational speed based on the frequency (or
period).
[0169] When embodying this example, when torque is not being
transmitted, the location of the magnetic poles of the detected
sections 39d, 40d are shifted at an electrical angle of 90 degrees
with respect to the circumferential direction, or in other words,
it is possible to make the center of the magnetic poles of one of
the detected sections face in the radial direction the boundary
between magnetic poles of the other detected section. In this case,
opposite from the explanation above, the output of the
magnetism-detecting element becomes a minimum when torque is not
being transmitted, and becomes larger as the torque being
transmitted becomes larger.
[0170] Moreover, when embodying this example, it is also possible
to use a coil instead of using a magnetism-detecting element as the
detecting section of the sensor 42d of the sensor unit 12c. When
using a coil, the center axis of the coil is made to coincide with
the radial direction of the first and second detected sections 39d,
40d. When using this kind of construction, as the detected sections
39d, 40d rotate together with the rotary-shaft unit 6, the
direction and size of the magnetic flux that passes through the
coil changes periodically, so the output (voltage, current) of the
coil, which is the output signal of the sensor unit 12c, changes
periodically. The frequency (and period) of this output is a value
that corresponds with the rotational speed, so it is possible to
find the rotational speed based on the frequency (or period).
Moreover, the density of the magnetic flux that passes
perpendicular to the coil changes according to the size of the
torque (amount of shift in the position in the circumferential
direction of the different poles of the detected sections 39d,
40d). Therefore, the size of the output of the coil changes
according to the size of the torque. However, as in the case of the
sensor unit 12a of the ninth example of an embodiment (see FIG. 25
to FIG. 28), the size of the output of the coil also changes
according to the rotational speed. Therefore, as in the case of the
ninth example of an embodiment, after the rotational speed is found
based on the frequency (or period) of the output of the coil,
correction is performed to return the size of the output that was
changed due to the effect of the rotational speed to the original
size. By doing so, it is possible to accurately find the torque
based on the size of the output after this correction.
[0171] In this example as well, it is sufficient to install only
one sensor 42d in the sensor unit 12c, so it is possible to
suppress the cost of the sensor unit 12c. It is also possible to
use construction in which the direction that the detected sections
of the first and second encoders face the one sensor of the sensor
unit is changed from the radial direction to the axial direction.
In that case, the detected sections of the first and second
encoders are a pair of circular disk-shaped detected sections that
have the same radial dimensions, and are arranged so that these
detected sections face each other in the axial direction. The
detecting section of the one sensor of the sensor unit is arranged
between these detected sections. The other construction and
functions are the same as those of the first through eighth
examples of embodiments.
Thirteenth Example
[0172] FIG. 43 illustrates a thirteenth example of an embodiment of
the present invention. In this example, the first and second
encoders 10, 11 and the sensor unit 12 are arranged so as to be
concentrated around one end section of the input shaft 13. More
specifically, the outer-circumferential surface of the other end
section (left-end section in FIG. 43 of the coupling shaft 9a that
is arranged on the inner-diameter side of the torsion bar 15 is
connected to the inner-circumferential surface of the other end
section of the output shaft 14 by an involute spline connection or
key connection so that relative rotation is not possible. Moreover,
a retaining ring (not illustrated in the figure) is used to prevent
displacement in the axial direction of the coupling shaft 9a with
respect to the output shaft 14. On the other hand, one end section
of the coupling shaft 9a (right-end section in FIG. 43) protrudes
from an opening on the one end side of the input shaft 13. The
first encoder is fastened around the outside of the one-end section
of the coupling shaft 9a, and the second encoder is fastened around
the outside of the one end section of the input shaft 13. Moreover,
with the detecting section of a pair of sensors of the sensor unit
12 facing the detected sections of these encoders 10, 11, the
sensor unit 12 is supported by the housing (not illustrated in the
figure). FIG. 43 is a simplified drawing, and part of the drawing
and reference numbers are omitted. The other construction and
functions are the same as those of the first example of an
embodiment.
Fourteenth to Seventeenth Examples
[0173] FIG. 44 to FIG. 47 illustrate fourteenth to seventeenth
examples of embodiments of the present invention. In these
examples, the arrangement of the thirteenth example of an
embodiment is applied to the construction of the ninth to twelfth
examples of embodiments, and the first and second encoders 10a to
10d, 11a to 11d and the sensor units 12a to 12d are arranged so as
to be concentrated around one end of the input shaft 13. FIG. 44 to
FIG. 47 are simplified drawings, and part of the drawing and
reference numbers are omitted. The other construction and functions
are the same as those of the ninth to twelfth examples and
thirteenth example of embodiments.
Eighteenth and Nineteenth Examples
[0174] FIG. 48 and FIG. 49 illustrate eighteenth and nineteenth
examples of embodiments of the present invention. In the
construction of an eighteenth example of an embodiment illustrated
in FIG. 48, in regard to the combination section of the end
sections of the input shaft 13 and the output shaft 14, of the
radial bearing and thrust bearing that are installed in this
combination section, the radial bearing is a cylindrical sleeve
bearing 57, which is a radial sliding bearing, and the thrust
bearing is a thrust needle bearing 58. The thrust needle bearing 58
is fastened around the outside of the base-end section of the
input-side combination cylindrical section 16 so that there is no
large looseness in the radial direction, and as a result, the
position of thrust needle bearing 58 is set in the radial
direction.
[0175] On the other hand, in the construction of the nineteenth
example of an embodiment illustrated in FIG. 49, the radial bearing
and thrust bearing that are installed in the combination section of
the input shaft 13 and output shaft 14 are a cylindrical shaped
sleeve bearing 57 and a circular disk-shaped thrust washer 21c. By
fastening the thrust washer 21c around the outside of the base-end
section of the input-side combination cylindrical section 16 so
that there is no large looseness in the radial direction, the
position of the thrust washer 21c is set in the radial direction.
Moreover, the thrust washer 21c is such that by fitting a pin 59
that is embedded in the stepped surface 19 in an engagement hole 60
that is formed in part of the thrust washer 21c itself, the
position in the circumferential direction of the thrust washer 21c
is set.
[0176] In either case, an oil passage 61 is formed in the base-end
section of the input-side combination cylindrical section 16.
Lubrication oil can be supplied though this oil passage 61 from a
cylindrical space 47 to the space where the radial bearing is
installed and the space where the thrust bearing is installed,
which improves the lubrication of these bearings. The other
construction and functions are the same as those of the first
through eighteenth examples of embodiments.
Twentieth Example
[0177] FIG. 50 illustrates a twentieth example of an embodiment of
the present invention. In the rotation transmission device, it is
important that that a spring section 115, which is the portion in
the middle section in the axial direction of the torsion bar 15
(see FIG. 5 and FIG. 6) that undergoes torsional deformation when
torque is transmitted, does not break (fracture) due to fatigue
even when torque is repeatedly transmitted. Moreover, in order to
sufficiently maintain the precision and resolution of torque
measurement, it is also important to sufficiently maintain the
amount of elastic torsional deformation per unit torque of the
torsion bar 15. In the rotation transmission device of this
example, the construction of the torsion bar 15 is devised so that
maintaining the durability necessary for preventing the spring
section 115a of the torsion bar 15 from breaking due to repeated
transmission of torque, and maintaining the amount of elastic
torsional deformation (twist angle) per unit torque that is
required in order to improve the precision and resolution of torque
measurement are both achieved to a high degree.
[0178] In this example, the spring section 115a of the torsion bar
15a includes a cylindrical tube section 78 in the middle section in
the axial direction except for the portions on both end edges in
the axial direction, that has thinner wall thickness than the
portions on both end edges in the axial direction, and is a single
cylindrical surface of which the inner-circumferential surface and
outer-circumferential surface are concentric with each other. In
other words, the inner-circumferential surface of the center hole
of the torsion bar 15a, including the middle section in the axial
direction, which is the inner-circumferential surface of the spring
section 115a, is a single cylindrical surface along the entire
length. On the other hand, of the spring section 115a, the
outer-circumferential surface of the cylindrical tube section 78 is
a single cylindrical surface that is concentric with the
inner-circumferential surface of the center hole of the cylindrical
tube section 78. Therefore, the wall thickness in the radial
direction of the cylindrical tube section 78 is uniform overall. On
the other hand, the outer-circumferential surfaces of the portions
on both end edges in the axial direction of the spring section 115a
are inclined in a direction so that the dimension of the diameter
becomes larger going toward both ends in the axial direction of the
spring section 115a, and form a pair of inclined surface sections
79. The outer-circumferential surface of the cylindrical tube
section 78 and a pair of male involute spline sections 62, 64 on
both end sections in the axial direction of the
outer-circumferential surface of the torsion bar 15a are provided
so as to be continuous by way of the pair of inclined surface
sections 62, 64. Therefore, the portions on both end edges in the
axial direction of the spring section 115a where the inclined
surface sections 79 are provided are such that the wall thickness
in the radial direction becomes larger than that of the cylindrical
tube section 78. In other words, the wall thickness in the radial
direction of the spring section 115a is a minimum in the
cylindrical tube section 78. The dimension s in the axial direction
of this cylindrical tube section 78 is greater than the width W in
the axial direction of the input gear 7 and the outer gear 8 (see
FIG. 6) (s>W).
[0179] The wall thickness in the radial direction of the spring
section 115a is a minimum in the cylindrical tube section 78, so
the torsional rigidity per unit length of the spring section 115a
is also a minimum in the cylindrical tube section 78. Therefore,
the amount of elastic torsional deformation per unit length that
occurs in the spring section 115a when torque is being transmitted
becomes a maximum in the cylindrical tube section 78. The spring
section 115a, except for the edge portions on both ends in the
axial direction, is mostly the cylindrical tube section 78.
Consequently, the amount of elastic torsional deformation that
occurs in the spring section 115a when torque is being transmitted
mostly occurs in the cylindrical tube section 78. Therefore, in
order to achieve with a high degree both the maintenance of
durability of the spring section 115a, and maintenance of the
elastic torsional deformation per unit torque, it is necessary to
focus on the construction of the cylindrical tube section 78.
Taking conditions such as these into consideration, in this
example, by adjusting the ratio di/do of the inner-diameter
dimension di and outer-diameter dimension do of the cylindrical
tube section 78, this ratio di/do is put within the
0.5.ltoreq.di/do.ltoreq.0.8. Together with this, by performing a
polishing process in order to improve the surface roughness of the
outer-circumferential surface of the cylindrical tube section 78,
the ten-point average roughness Rz of the outer-circumferential
surface of the cylindrical tube section 78 is put within the range
Rz.ltoreq.22 .mu.m. Furthermore, of the surface of the torsion bar
15a, at least the hardness of the outer-circumferential surface of
the spring section 115a is made to be 450 Hv (and preferably 500 Hv
or greater).
[0180] Normally, spring steel (JIS G 4801) is used as the material
of a typical torsion bar that is used in various kinds of
machinery. Spring steel includes silicon manganese steel (SUPE,
SUPT), manganese chromium steel (SUP9, SUP9A), chromium vanadium
steel (SUP10), manganese chromium boron steel (SUP11A), silicon
chromium steel (SUP 12), and chromium molybdenum steel (SUP13); and
the mechanical properties of these are a yield stress (0.2% yield
strength): 100 to 1100 MPa, and hardness: 350 Hv to 450 Hv.
[0181] On the other hand, for the spring section 115a of the
torsion bar 15a of the rotation transmission device with torque
measurement device of this example, in order to achieve a high
degree of both maintenance of durability and maintenance of elastic
torsional deformation per unit torque, using a material having a
high yield stress .sigma.y and fatigue strength .sigma.w as the
material of the torsion bar 15a is effective; and more
specifically, using a material having a yield stress .sigma.y of
1100 MPa or greater (and preferably 1200 MPa or greater) and a
fatigue strength .sigma.w of 500 MPa or greater (an preferably 600
MPa or greater) is effective. Moreover, there is a correlation
between the yield stress .sigma.y and fatigue strength .sigma.w and
the hardness, and a hard hardness is preferred. More specifically,
as done in this example, making the hardness of at least the
outer-circumferential surface of the spring section 115a of the
surface of the torsion bar 15a 450 Hv (upper limit of the hardness
of the spring steel material used as the material for a typical
torsion bar as described above) or greater (and preferably 500 Hv
or greater) is effective. However, in the case that this hardness
is too high, the material becomes brittle, and the impact strength
greatly decreases. Therefore, this hardness is made to be 850 Hv or
less (and preferably, 800 Hv or less).
[0182] In order to make the hardness of at least the
outer-circumferential surface of the spring section 115a of the
surface of the torsion bar 15a 450 Hv or greater, a material having
a higher carbon concentration than the spring steel (JIS G 4801,
carbon concentration of 0.45 to 0.65%) that is used as the material
of a typical torsion bar is used as the metal material of the
torsion bar 15a, for example. In other words, the carbon
concentration of the metal material of the torsion bar 15a is 0.65%
or greater (and preferably, 0.7% or greater). As a result, when
martensite is generated by performing a tempering and annealing
process on the metal material of the torsion bar 15a, the hardness
can be improved. However, when this carbon concentration becomes
too high, large carbides are generated, and thus workability
greatly worsens and toughness greatly decreases. Therefore, the
carbon concentration is made to be 1.5% or less (and preferably,
1.25% or less, and even more preferably, 1.2% or less). More
specifically, high carbon chromium bearing steel (carbon
concentration: 0.9 to 1.1%) or carbon tool steel (carbon
concentration: 0.65 to 1.5%) is used as the metal material of the
torsion bar, and tempering is performed at 800 to 860.degree. C.,
after which annealing is performed at 150 to 500.degree. C.
[0183] Alternatively, spring steel is used as the metal material of
the torsion bar 15a, and the torsion bar 15a is made by performing
annealing at a temperature (450.degree. C. or less, and preferably
400.degree. C.) that is lower than the annealing temperature (450
to 570.degree. C.) for normal spring steel. More specifically, the
torsion bar 15a is made by performing tempering of the spring steel
at 800 to 880.degree. C., and then performing annealing at 150 to
450.degree. C.
[0184] Alternatively, it is possible to perform a carburizing
process or carbo-nitriding process on the surface of the torsion
bar 15a. In other words, by performing a carburizing process or
carbo-nitriding process, it is possible to deposit much carbide of
nitride onto the surface of the torsion bar 15a. More specifically,
the torsion bar 15a is made by performing a carburizing process in
a carburizing gas atmosphere of propane, methane, butane gas or the
like at 700.degree. C. to 900.degree. C. on a machine structure
carbon steel (JIS G 4052) or machine structure alloy (JIS G 4053:
nickel chromium steel, nickel chromium molybdenum steel, chromium
steel, chromium molybdenum steel, manganese steel, manganese
chromium steel or the like), or performing a carbo-nitriding
process in a mixed atmosphere of a carburizing gas and ammonia gas,
and then performing an annealing process at 150.degree. C. to
500.degree. C. As a result, it is possible to sufficiently maintain
the wear resistance of the connecting sections (male involute
spline sections 62, 64 or key sections) that are provided on the
outer-circumferential surfaces of both end sections of the torsion
bar 15a that connect with the input shaft 13 or output shaft 14
(see FIG. 5 and FIG. 6).
[0185] Alternatively, it is also possible to perform a shot-peening
process on the outer-circumferential surface of the torsion bar
15a. More specifically, the torsion bar 15a is made by performing a
tempering process at 830.degree. C. to 870.degree. C. on a spring
steel material, and then performing an annealing process at
460.degree. C. to 570.degree. C., and when necessary, further
performing a polishing process, and then finally performing a
shot-peening process. Shot-peening balls made of a material such as
steel, glass or ceramic and having a diameter of 0.1 to 1 mm are
used in the shot-peening process. By performing this kind of
shot-peening process, not only is it possible to improve the
hardness of the torsion bar 15a, but it is also possible to improve
the fatigue strength by generating compressive residual stress. The
compressive residual stress on the surface layer of the torsion bar
15a is preferably 200 MPa or greater. In addition to the
outer-circumferential surface of the torsion bar 15, the
shot-peening process can also be performed on the
inner-circumferential surface.
[0186] In this example, the ratio di/do of the inner-diameter
dimension di and the outer-diameter dimension do of the cylindrical
tube section 78, and the ten-point average roughness of the
outer-circumferential surface Rz of the cylindrical tube section 78
are kept within the respective ranges described above
(0.5.ltoreq.di/d.ltoreq.0.8, R.ltoreq.22 .mu.m), so it is possible
to maintain at a high degree both durability and the amount of
elastic torsional deformation of the spring section 115a, of which
the cylindrical tube section 78 is the main portion.
[0187] In other words, in this example, the ratio di/do of the
inner-diameter dimension di and outer-diameter dimension do of the
cylindrical tube section 78 is 0.8 or less (di/do.ltoreq.0.8), so
the maximum shear stress that acts on the outer-circumferential
surface of the cylindrical tube section 78 can be kept low. At the
same time, the ten-point average roughness Rz of the
outer-circumferential surface of the cylindrical tube section 78 is
22 .mu.m or less (Rz.ltoreq.22 .mu.m), so even when the maximum
shear stress is repeatedly applied to the outer-circumferential
surface of the cylindrical tube section 78, it is possible to make
it difficult for cracking, which is the start of fatigue fracture,
to occur on the outer-circumferential surface of the cylindrical
tube section 78.
[0188] In this example, the ratio di/do of the inner-diameter
dimension di and outer-diameter dimension do of the cylindrical
tube section 78 is 0.5 or greater (0.5.ltoreq.di/do), so it is
possible to prevent the wall thickness (torsional rigidity) in the
radial direction of the cylindrical tube section 78 from becoming
excessively large, and thus it is possible to sufficiently maintain
the amount of elastic torsional deformation per unit torque in the
spring section 115a.
[0189] Furthermore, in this example, of the surface of the torsion
bar 15a, the hardness of the outer-circumferential surface of at
least the spring section 115a is 450 Hv or greater (and preferably,
500 Hv or greater). Therefore, it is possible to more easily
maintain the durability of the spring section 115a of the torsion
bar 15a.
[0190] For the spring section 115a of the torsion bar 15a, it is
important to maintain at a high degree, both the durability
required for preventing fatigue fracture due to repeatedly
transmitting torque, and the amount of elastic torsional
deformation per unit torque that is necessary for improving the
precision and resolution of torque measurement.
[0191] When torque T is applied to the cylindrical tube section 78
(outer-diameter dimension do, inner-diameter dimension di,
dimension in the axial direction s, modulus of rigidity G), which
is the main part of the spring section 115a of the torsion bar 15a,
the maximum shearing stress .tau.max that acts on the cylindrical
tube section 78 is as expressed by Equation (1). The maximum
shearing stress max acts on the outer-circumferential surface of
the cylindrical tube section 78.
.tau. max = 16 T d o .pi. ( d o 4 - d i 4 ) ( 1 ) ##EQU00001##
[0192] Moreover, the twisting angle .phi. of the cylindrical tube
section 78 when a torque T is applied to the cylindrical tube
section 78 is as expressed by Equation (2)
.phi. = 32 T s G .pi. ( d o 4 - d i 4 ) ( 2 ) ##EQU00002##
[0193] As can be understood from Equation (1), when the
inner-diameter dimension di is made small with respect to the
outer-diameter dimension do, the maximum shearing stress .tau.max
becomes small by that amount, so it become difficult for fatigue
fracture to occur in the cylindrical tube section 78. Therefore,
the durability of the spring section 115a, of which the cylindrical
tube section 78 is the major part, is improved the smaller the
inner-diameter dimension di is with respect to the outer-diameter
dimension do.
[0194] On the other hand, as can be understood from Equation (2),
as the inner-diameter dimension di becomes large with respect to
the outer-diameter dimension do, the twisting angle .phi. becomes
larger by that amount. In other words, the amount of elastic
torsional deformation of the cylindrical tube section 78 becomes
larger. Therefore, the amount of elastic torsional deformation per
unit torque of the spring section 115a, of which the cylindrical
tube section 78 is the major part, becomes larger the larger the
inner-diameter di is with respect to the outer-diameter dimension
do.
[0195] As can be understood from the explanation above, in order to
maintain at a high degree both durability and the amount of elastic
torsional deformation per unit torque for the spring section 115a,
it is necessary to keep the ratio di/do of the inner-diameter
dimension di and outer-diameter dimension do of the cylindrical
tube section 78 within a specified range.
[0196] In the following, testing that was performed in order to
confirm the effect of the invention will be explained. In this
testing, the effect that the ratio di/do of the inner-diameter
dimension di and outer-diameter dimension do of the cylindrical
tube section 78 has on the durability and the amount of elastic
torsional deformation per unit torque of the spring section 115a,
or in other words, the precision (resolution) of torque measurement
was investigated.
[0197] In order for this, as a test specimen, plural torsion bars
15a having ratios di/do of the inner-diameter dimension di and
outer-diameter dimension do of the cylindrical tube section 78 that
were different from each other were prepared, and testing of these
specimens was performed by applying a torque load to the spring
section 115a. More specifically, in order to perform this testing,
a tester such as illustrated in FIG. 51 was used. In other words,
of the torsion bar 15a, one end section that is separated from the
spring section 115a (left end section in FIG. 51) and one end
section of the coupling shaft 9 that is passed through the center
hole of the torsion bar 15a (left end section in FIG. 51) are
fastened around the inside of a fixed first fastener 80, and of the
torsion bar 15a, the other end section that is separated from the
spring section 115a (right end section in FIG. 51) is fastened
around the outside of a movable second fastener 81. Moreover, a
first encoder 10 is fastened around the outside of the other end
section (right end section in FIG. 51) of the coupling shaft 9, and
a second encoder 11 is fastened around the outside of the second
fastener 81. Furthermore, with the detecting sections of a pair of
sensors of a sensor unit 12 facing the detected sections of the
first and second encoders 10, 11, the sensor unit 12 is supported
by and fastened to a fixed support (not illustrated in the figure).
In this state, a hydraulic device (not illustrated in the figure)
rotates the second fastener 81, which applies a torque to the
spring section 115a of the torsion bar 15a. The other test
conditions are as given below.
<Torsion Bar 15a> Material: DSUP9A (manganese chromium steel)
Outer-diameter dimension do of the cylindrical tube section 78: 30
mm Inner-diameter dimension do of the cylindrical tube section 78:
Differs for each specimen. Axial direction dimension s of the
cylindrical tube section 78: 80 mm Ten-point average roughness of
the outer-circumferential surface of the cylindrical tube section:
Approx. 60 .mu.m
<Durability Test>
[0198] Using the tester described above, a fixed torque T that was
selected from among the range 500 to 2000 Nm was repeatedly applied
as a load to the spring section 115a of the torsion bar 15a test
specimen at a frequency of 20 Hz. Then, the size of the fatigue
limit torque Tw, which is the torque T at the limit where fatigue
failure does not occur in the cylindrical tube section 78 even
after loading is repeatedly applied a total of 1.0.times.10.sup.7
times, was found.
<Torque Measurement Precision (Resolution) Test>
[0199] The tester described above was used, and a 500 Nm torque T
was repeatedly applied as a load to the spring section 115a of the
torsion bar 15 specimens. When doing this, the variation width in
the torque measurement values that was found based on the phase
difference ratio of the output signals from the pair of sensors,
and the measurement error of the torque measurement was found by
dividing the variation width by the torque T (500 Nm) load.
[0200] The results (fatigue limit torque Tw, torque measurement
error) of the tests above are given in Table 1.
TABLE-US-00001 TABLE 1 Fatigue limit Torque di/do torque Tw (Nm)
measurement error 0.9 550 5% 0.8 1050 5% 0.7 1200 5% 0.6 1350 6%
0.5 1500 6% 0.4 1600 12% 0.3 1700 21%
[0201] When using a rotation transmission device that is installed
in a transmission of an automobile, fatigue fracture must not occur
even when a torque T of 1000 Nm or less is repeatedly applied, or
in other words, the rotation transmission device must have a
fatigue limit torque Tw that is greater than 1000 Nm. As can be
clearly seen from the test results in Table 1, in order to
sufficiently maintain the durability of the spring section 115a in
order to meet this demand, it is necessary that the radio di/do be
0.8 or less (di/do.ltoreq.0.8).
[0202] On the other hand, in regard to the precision (resolution)
of the torque measurement, as can clearly be seen from the test
results in Table 1, when the ratio di/do becomes 0.5 or greater
(0.5.ltoreq.di/do), the error of the torque measurement rapidly
decreases (6% or less). Therefore, in order to sufficiently
maintain the precision (resolution) of torque measurement, the
ratio di/do should be 0.5 or greater (0.5.ltoreq.di/do).
[0203] From the test results described above, it was learned that
in order to maintain at a high degree both the durability and the
amount of elastic torsional deformation per unit torque, or in
other words, the precision (resolution) of torque measurement, for
the spring section 115a of the torsion bar 15a, the ratio di/do
should be kept within the range 0.5.ltoreq.di/do.ltoreq.0.8.
[0204] Incidentally, when a torque load is applied to the spring
section 115a of the torsion bar 15a, the maximum shearing stress
.tau.mas in Equation (1) acts on the outer-circumferential surface
of the cylindrical tube section 78. Therefore, when the cylindrical
tube section fractures due to fatigue, first, cracking occurs on
the outer-circumferential surface, and that cracking progresses
toward the inside until fracture occurs. In this case, when the
surface roughness of the outer-circumferential surface is large,
minute unevenness on the outer-circumferential surface becomes the
cause of concentrated stress, and it becomes easy for cracking to
occur, so the fatigue strength decreases by that amount.
[0205] Therefore, in order to investigate the effect that the
surface roughness of the outer-circumferential surface of the
cylindrical tube section 78 has on the fatigue strength, the
inventors performed additional testing. In other words, in the
previous testing, material (material having a ten-point average
roughness Rz of the outer-circumferential surface of the
cylindrical tube section 78 of about 60 .mu.m) that was obtained by
performing only heat treatment of the spring section 115a as in the
case of a typical torsion bar that is assembled and used in various
machinery was used for each of the plural torsion bar 15a
specimens. However, in this additional testing, plural torsion bars
15a were prepared as the test specimens so that the ratio di/do of
the inner-diameter dimension di and outer-diameter dimension do of
the cylindrical tube section 78 was 0.6 for each, and so that the
ten-point average roughness Rz of the outer-circumferential surface
of the cylindrical tube section 78 differed from each other. The
ten-point average roughness Rz was adjusted by polishing the
outer-circumferential surface of the cylindrical tube section 78
after heat treatment of the spring section 115a was performed. The
size of the fatigue limit torque Tw of the cylindrical tube section
78 was investigated for these specimens under the same conditions
as in the previous testing. The results (fatigue limit torque Tw)
of this additional testing are given in Table 2.
TABLE-US-00002 TABLE 2 Ten-point average Fatigue limit roughness Rz
(.mu.m) torque Tw (Nm) 60 1350 51 1400 39 1450 33 1500 22 1600 9
1600
[0206] As can clearly be seen from the test results in Table 2,
when the ten-point average roughness Rz becomes 22 .mu.m or less
(Rz.ltoreq.22 .mu.m), the fatigue limit torque Tw becomes
sufficiently large, and becomes a fixed size (1600 Nm). From this
it was learned that by making the ten-point average roughness Rz 22
.mu.m or less (Rz.ltoreq.22 .mu.m), it is possible to prevent
minute unevenness on the outer-circumferential surface of the
cylindrical tube section 78 from becoming the source of
concentrated stress, and is useful for sufficiently maintaining the
durability of the spring section 115a.
[0207] In the explanation above, an example was given of a case of
applying the construction of the torsion bar 15 of this example to
the construction of the first example of an embodiment. However,
this example is not limited to this, and it is also possible to
apply this construction to other examples of embodiments of the
present invention.
Twenty-First Example
[0208] FIG. 52 illustrates a twenty-first example of an embodiment
of the present invention. A feature of the rotation transmission
device of this example the reduction in manufacturing cost by
integrating part of the members of this device. In other words, an
input-side rotating body 82 is constructed by fastening an input
gear 7 around the outside of the middle section in the axial
direction of an input-side unit 83 so as to be concentric with the
input-side unit 83, and so as to be able to rotate in
synchronization with the input-side unit 83. Moreover, the
input-side unit 83 is an integrally formed part that is formed by
integrating together an input shaft 13c, an inner ring 30e of a
conical roller bearing 29e that supports the input shaft 13c so as
to be able to freely rotate with respect to the housing, and a
torsion bar 15b. The input-side unit 83 is such that a stepped
surface 27 that faces one end side in the axial direction of the
input shaft 13c is provided around the outer-circumferential
surface of the middle section in the axial direction. The
input-side unit 83 is made by performing plastic working such as
forging or by cutting a metal material such as a chromium steel
like SCr420 or SCM420, or a chromium molybdenum steel such as
SCM420 or the like, and then performing heat treatment such as
carburizing or carbo-nitriding.
[0209] Moreover, the input gear 7 is positioned in the axial
direction with respect to the input-side unit 83 by the portion
near the inner circumference of one side surface (left side surface
of FIG. 52) coming in contact with the stepped surface 27. In this
state, the input gear 7 is prevented from displacing in the axial
direction with respect to the input-side unit 83 by a retaining
ring engaging with a portion on the outer-circumferential surface
of the input-side unit 83 that comes in contact with the one end
side in the axial direction of the input gear 7. In this example,
the inner-diameter dimension of the input gear 7 is larger than the
outer-diameter dimension of the inner ring 30e. As a result, input
gear 7 is able to pass over the inner ring 30e when installing the
input gear 7 in the input-side unit 83 or removing the input gear
from the input-side unit 83.
[0210] In this example, the input shaft 13c, the inner ring 30e of
the conical roller bearing 29e that supports the input shaft so as
to be able to freely rotate with respect to the housing, and the
torsion bar 15b are integrally formed, so it is possible to
suppress the cost of managing parts and the assembly cost.
Furthermore, there is no need for parts such as the retaining ring
25a, spacer 31, nut 32a and the like that are used for assembling
the members 13c, 30e, 15b so as not to separate from each other;
and from this aspect as well, it is possible to suppress the cost
of managing parts. As a result, it is possible to reduce the
manufacturing cost of the rotation transmission device.
[0211] When embodying this example, it is also possible to
integrally form an output shaft 14, and an inner ring 30b of a
conical roller bearing 29b that supports the output shaft 14 so as
to rotate freely with respect to the housing. As a result, it is
possible to further suppress the cost of managing parts and the
assembly cost, and thus it is possible to further reduce the
manufacturing cost of the rotation transmission device. The other
construction and functions are the same as those of the first
through twentieth examples of embodiments.
Twenty-Second Example
[0212] FIG. 53 illustrates a twenty-second example of an embodiment
of the present invention. In this example, in addition to the inner
ring 30e, input shaft 13c and torsion bar 15b, the input gear 7a is
also integrally formed. Therefore, the input gear 7a does not need
to be formed as an independent part, and thus it is possible to
eliminate parts such as the retaining ring for preventing the input
gear 7a from displacing in the axial direction with respect to the
input shaft 13c. Consequently, it is possible to suppress the cost
for managing parts and the assembly cost by that amount, and thus
it is also possible to further reduce the manufacturing cost of the
rotation transmission device. The other construction and functions
are the same as those of the twenty-first example of an
embodiment.
Twenty-Third Example
[0213] FIG. 54 illustrates a twenty-third example of an embodiment
of the present invention. In this example, an output-side rotating
body 84 is formed by fastening an output gear 8a around the outside
of the middle section in the axial direction of an output-side unit
85 so as to be concentric with the output-side unit 85, and so as
to be able to rotate in synchronization with the output-side unit
85. The output-side unit 85 is an integrally formed part by
integrally forming an output shaft 14a, an inner ring 30f of a
conical roller bearing 29f that supports the output shaft 14a so as
to rotate freely with respect to a housing, and a torsion bar 15c.
The output-side unit 85 is such that a stepped surface 86 that
faces toward the other end side in the axial direction of the
output shaft 14a is provided around the outer-circumferential
surface of the middle section in the axial direction. The
output-side unit 85 is made by performing plastic working such as
forging or by cutting a metal material such as a chromium steel
like SCr420 or SCM420, or a chromium molybdenum steel such as
SCM420 or the like, and then performing heat treatment such as
carburizing or carbo-nitriding.
[0214] The output gear 8a is positioned in the axial direction with
respect to the output-side unit 85 by one side surface (right side
surface in FIG. 54) of the output gear 8a coming in contact with
the stepped surface 86. In this state, the output gear 8a is
prevented from displacement in the axial direction with respect to
the output-side unit 85 by a retaining ring or the like engaging
with a portion on the outer-circumferential surface of the
output-side unit 85 that is in contact with the other side in the
axial direction of the output gear 8a. The inner-diameter dimension
of the output gear 8a is larger than the outer-diameter dimension
of the inner ring 30d, so it is possible to pass the outer gear 8a
in the axial direction over the inner ring 30f when installing the
outer gear 8a in the output-side unit 85 or removing the output
gear 8a from the output-side unit 85.
[0215] In this example, the output shaft 14a, the inner ring 30f of
the conical roller bearing 29f and the torsion bar 15c are
integrally formed, so it is possible to suppress the cost of
managing parts and assembly costs. Furthermore, there is no need
for parts such as a retaining ring 25b and nut 32b that are used
for assembling these members 14a, 30f, 15c so as not to separate
from each other, and so from this aspect as well, it is possible to
suppress the cost of managing parts. Therefore, it is possible to
reduce the manufacturing cost of the rotation transmission
device.
[0216] When embodying this example as well, it is also possible to
integrate the input shaft 13, and inner ring 30a of the conical
bearing 29a that supports the input shaft 13 so as to rotate freely
with respect to the housing. In that case, it is necessary to make
the inner-diameter dimension of the input gear 7 larger than the
outer-diameter dimension of the inner ring 30a so that the input
gear 7 is able to pass in the axial direction over the inner ring
30a when installing or removing the input gear 7. By integrating
the input shaft 13 and inner ring 30a, it is possible to further
suppress the cost of managing parts and assembly costs, and thus it
is possible to further reduce the manufacturing cost of the
rotation transmission device with torque measurement device. In
addition to the input shaft 13 and inner ring 30a, it is also
possible to integrate the input gear 7. The other construction and
functions are the same as those of the first through twentieth
examples of embodiments.
Twenty-Fourth Example
[0217] FIG. 55 illustrates a twenty-fourth example of an embodiment
of the present invention. In this example, in addition to the inner
ring 30f, the output shaft 14a and torsion bar 15c, the output gear
8 is also integrally formed. Therefore, there is no need to form
the output gear 8 as an independent part, and it is possible to
eliminate installing parts for preventing the output gear 8 from
displacing in the axial direction with respect to the output shaft
14c. Consequently, it is possible to suppress the cost of managing
parts and the assembly cost, and to further reduce the
manufacturing cost of the rotation transmission device by that
amount. The other construction and functions are the same as those
of the twenty-third example of an embodiment.
Twenty-Fifth Example
[0218] FIG. 56 and FIG. 57 illustrate a twenty-fifth example of an
embodiment of the present invention. In this example, the amount of
run-out of the first encoder 10 with respect to the second encoder
11 that is associated with error in the torque measurement is kept
small by improving the concentricity of the centers of rotation of
the first and second encoders 10, 11. In this example as well, the
first encoder 10 is concentrically fastened around the other end
section of the coupling shaft 9. The first encoder has a metal core
35 made of a magnetic metal, and a permanent magnet 37. The metal
core 35 includes: a cylindrical shaped fitting cylindrical section
87 that fits onto the coupling shaft 9; an outward-facing flange
shaped wheel section 88 that is provided around the middle section
in the axial direction of the fitting cylindrical section 87; and a
cylindrical section 89 that is provided in a direction toward one
end side in the axial direction of the coupling shaft 9 from the
outer-circumferential edge of the cylindrical section 89. Moreover,
the permanent magnet 37 is fastened around the entire
outer-circumferential surface of the cylindrical section 89.
[0219] In this example, a sliding bearing 91 that is made of a
material that slides easily such as oil-impregnated metal,
synthetic resin or the like is provided between a large-diameter
section 90 that is provided on the outer-circumferential surface of
the other end section of the output shaft 14b and the
outer-circumferential surface of one end section (right-end section
in FIG. 57) of the fitting cylindrical section 87. More
specifically, first, the coupling shaft 9 is supported by the input
shaft 13 by connecting the outer-circumferential surface of a rim
section 34 that is formed on one end section of the coupling shaft
9 and the inner-circumferential surface of one end section of the
input shaft 13 by an involute spline connection 24d. In this state,
the rim section 34 is held on both sides in the axial direction by
a pair of retaining rings 25a, 25c that are fastened around the
inner-circumferential surface of the input shaft 13, which prevents
the coupling shaft 9 from displacing in the axial direction with
respect to the input shaft 13. Next, the hollow cylindrical shaped
torsion bar 15 is inserted into the inner-diameter sides of the
input shaft 13 and output shaft 14b from the opening on the other
end side of the output shaft 14b. Then an involute spline
connection 24a is formed by connecting a first male involute spline
section 62 that is provided on the outer-circumferential surface of
one end section of the torsion bar 15 with a first female involute
spline section 63 that is provided on the inner-circumferential
surface of one end section of the input shaft 13, and an involute
connection 24b is formed by connecting a second male involute
spline section 64 that is provided on the outer-circumferential
surface of the other end section of the torsion bar 15 with a
second female spline section 65 that is provided on the
inner-circumferential surface of the other end section of the
output shaft 14b. As a result, the torsion bar 15 is supported on
the inner-diameter side of the input shaft 13 and output shaft 14b.
Next, the sliding bearing 91 is pressure fitted into the
large-diameter section of the output shaft 14b, and one side
surface (right-side surface in FIG. 57) of the sliding bearing 91
is pressed against the other end surface of the torsion bar 15. By
doing so, the torsion bar 15 is held on both sides in the axial
direction between the retaining ring 25a and sliding bearing 91,
which prevents the torsion bat 15 from displacing in the axial
direction with respect to the input shaft 13 and the output shaft
14b. Next, by fastening the metal core 36 of the second encoder 11
around the outside of the other end section of the output shaft
14b, the second encoder 11 is supported by the output shaft 14b so
as to be concentric with the output shaft 14b, and so as to rotate
in synchronization with the output shaft 14b. Next, an involute
connection 24e for preventing the relative rotation with respect to
a cylindrical surface connecting connection 26b for maintaining
concentricity is formed by fastening the fitting cylindrical
section 87 of the metal core 35 of the first encoder 10 onto a
small-diameter section 92 that is provided on the other end section
of the coupling shaft 9, and a retaining ring 25d prevents the
metal core 35 from displacing in the axial direction. As a result,
the first encoder 10 is fastened to and supported by the input
shaft 13 by way of the coupling shaft 9 so as to be concentric with
the input shaft 13, and so as to be able to rotate in
synchronization with the input shaft 13, and the
outer-circumferential surface of one end section (right-end section
in FIG. 57) of the fitting cylindrical section 87 is made to slide
over or closely face the inner-circumferential surface of the
sliding bearing.
[0220] The procedure for assembling the rotation transmission
device of this example is not limited to the procedure described
above. In other words, it is also possible to insert the coupling
shaft 9 into the inner-diameter side of the torsion bar 15 after
the torsion bar 15 is supported on the inner-diameter side of the
input shaft 13 and output shaft 14b, or it is also possible to
pressure fit the sliding bearing 91 into the other end section of
the output shaft 14b and then support the torsion bar 15 with the
rim section 34 of the coupling shaft 9 prevented from displacement
in the axial direction with respect to the input shaft 13 by the
pair of retaining ring 25a, 25c.
[0221] Moreover, it is also possible to cause the
outer-circumferential surface of the sliding bearing 91 to slide
over or closely face the large-diameter section 90 of the output
shaft 14b by pressure fitting the sliding bearing 91 onto the
outer-circumferential surface of one end section of the fitting
cylindrical section 87 of the metal core 35 of the first encoder
10.
[0222] In this example, a sliding bearing 91 is provided between
the large-diameter section 90 that is provided on the
inner-circumferential surface of the other end section of the
output shaft 14b and the outer-circumferential surface of one end
section of the fitting cylindrical section 87 of the metal core 35
of the first encoder 10, so it is possible to keep the amount of
run-out of the first encoder 10 with respect to the second encoder
11 that is associated with the error in torque measurement small.
In other words, the inner-circumferential surface of the sliding
bearing 91 that is pressure fitted into the large-diameter section
90 is made to slide over or closely face the outer-circumferential
surface of the fitting cylindrical section 87 that is fastened
around the outside of the other end section of the coupling shaft
9, so it is possible to improve the concentricity between the
center of rotation of the first encoder 10 that is fastened to and
supported by the other end section of the coupling shaft 9 and the
center of rotation of the second encoder 11 that is fastened to and
supported by the output shaft 14b. As a result, it is possible to
keep the amount of run-out of the first encoder 10 with respect to
the second encoder 11 small.
[0223] In this example, one side surface of the sliding bearing 91
that is pressure fitted into the large-diameter section 90 of the
output shaft 14b is pressed against the other end surface of the
torsion bar 15. Therefore, when compared with the case when the
torsion bar 15 is held on both sides in the axial direction by
retaining rings 25a, 25b that are fastened around the
inner-circumferential surfaces of the input shaft 13 and output
shaft 14 (14a) (see FIG. 6), it is possible to effectively prevent
looseness in the axial direction of the torsion bar 15 with respect
to the input shaft 13 and output shaft 14b. Moreover, it is not
necessary to provide a fastening groove for fastening the retaining
ring 25b (see FIG. 5 and FIG. 6) in the inner-circumferential
surface of the other end section of the output shaft 14b, so it is
possible to shorten the dimension in the axial direction of the
output shaft 14b, and thus it is possible to make the rotation
transmission device more compact and lightweight.
Twenty-Sixth Example
[0224] FIG. 58 illustrates a twenty-sixth example of an embodiment
of the present invention. A feature of this example, and in the
twenty-fifth example of an embodiment, is to keep the amount of
run-out of the first encoder 10 with respect to the second encoder
11 that is associated with error in torque measurement small by
improving the concentricity of the centers of rotation of the first
and second encoders 10, 11. In this example, the coupling shaft 9c
is supported by the input shaft 13d so as to be concentric with the
input shaft 13d and so as to rotate in synchronization with the
input shaft 13d by pressure fitting an outward-facing flange shaped
rim section 34b that is formed around the outer-circumferential
surface of one end section of the coupling shaft 9c into a
large-diameter section 93 that is provided around the
inner-circumferential surface of one end section of the input shaft
13d. Then, the other side surface (right-side surface in FIG. 58)
of the rim section 34b is pressed against one end surface
(right-end surface in FIG. 58) of the torsion bar 15, directly, or
in other words, not by way of another member.
[0225] In this example, the coupling shaft 9c is supported by the
input shaft 13d by pressure fitting the rim section 34b of the
coupling shaft 9c into the large-diameter section of the input
shaft 13d. Therefore, when compared with the case of supporting the
coupling shaft 9 by the input shaft by way of the involute spline
connection 24a, it is possible to improve the concentricity of not
only the center axis of the coupling shaft 9a and the center axis
of the input shaft 13a, but the center axis of the output shaft 14
as well. As a result, it is possible to further improve the
concentricity of the centers of rotation of the first and second
encoders 10, 11, and thus it is possible to keep the amount of
run-out of the first encoder 10 with respect to the second encoder
11 that is associated with error in torque measurement small.
[0226] Moreover, in this example, the other side surface of the rim
section 34b that is pressure fitted into the large-diameter section
93 of the input shaft 13d is pressed against one end surface of the
torsion bar 15. Therefore, compared with the case of holding the
torsion bar 15 on both sides in the axial direction by the
retaining rings 25a, 25b that are fastened around the
inner-circumferential surfaces of the input shaft 13 and output
shaft 14, it is possible to effectively prevent looseness in the
axial direction of the torsion bar 15 with respect to the input
shaft 13a and output shaft 14. Furthermore, there is no need to
provide fastening grooves around the inner-circumferential surface
of the other end section of the input shaft 13a for fastening the
retaining ring 25a, 25c, so it is possible to shorten the dimension
in the axial direction of the input shaft 13d, and thus it is
possible to make the rotation transmission device more compact and
lightweight. The twenty-fifth example and twenty-six example of
embodiments can be embodied at the same time.
Twenty-Seventh Example
[0227] FIG. 59 and FIG. 60 illustrate a twenty-seventh example of
an embodiment of the present invention. In this example, the
construction of the sensor unit 12d, and the construction for
supporting the sensor unit 12 by the housing (not illustrated in
the figures) is devised in order to simplify positioning of the
sensor unit 12d with respect to the first and second encoders 10,
11, and to improve the reliability of the torque measurement.
[0228] In this example, the output shaft 14 is supported by a
conical roller bearing 29g that is located between a portion near
the other end (left end in FIG. 59) of the outer-circumferential
surface of the output shaft 14 and the inner-circumferential
surface of the housing so as to rotate freely with respect to the
housing. However, the half of the outer ring 94 of the conical
roller bearing 29g near the other end side in the axial direction
functions as an extended cylindrical section 95 that protrudes
further in the axial direction than the end section on the
small-diameter side of the inner ring 30g of the conical roller
bearing 29g. The inner-circumferential surface of the extended
cylindrical section 95 is screwed onto the other end section of the
outer-circumferential surface of the output shaft 14 and tightened
so as to face the outer-circumferential surface of a nut 32b.
[0229] In this example, the sensor unit 12 includes a sensor cover
96, a sensor holder 97, and a first and second sensor 42a, 42b. The
sensor cover 96 is formed using metal sheet into a cylindrical
shape with a bottom, and includes a cover cylinder section 98 and a
cover bottom plate section 99 that covers the opening on the base
end of the cover cylinder section 98. Moreover, an outward-facing
flange shaped rim section 100 is provided on the portion near the
tip end of the outer-circumferential surface of the cover cylinder
section 98, and a through hole 101 is provided in part of the cover
bottom plate section 99 (portion near the outer circumference in
the example in the figure). The sensor holder 97 is formed into a
complete cylindrical shape with a bottom using a synthetic resin,
and is fastened to and supported by the inner surface of the sensor
cover 96 by insert molding or adhesive. First and second sensors
42a, 42b are embedded in the cylindrical portion of the sensor
holder 97 that is located on the inner-diameter side of the cover
cylinder section 98. Moreover, a connector section 102 that is
provided on part of the sensor holder 97 protrudes through the
through hole 101 to the outside of the sensor cover 96. The end
section of a harness for the output signals from the first and
second sensors 42a, 42b can be connected to or disconnected from
this connector section 102.
[0230] In this example, the sensor unit 12a having construction
such as described above is fastened to and supported by the housing
by way of an outer ring 94. More specifically, the tip-end section
of the cover cylinder section 98 of the sensor cover 96 is pressure
fitted into the inner-circumferential surface of the tip-end
section of the extended cylindrical section of the outer ring 94
and connected with an interference fit. Moreover, the sensor unit
12d is positioned in the axial direction with respect to the outer
ring 94 by bringing the side surface of a rim section 100 that is
provided on the portion near the tip end of the
outer-circumferential surface of the cover cylinder section 98 into
contact with the tip-end surface of extended cylindrical section
95. Then, in this state, the first and second encoders 10, 11 are
placed in a space on the inside of the sensor cover 96, and
detecting sections of the first and second sensors 42a, 42b are
made to face first and second detected sections 39, 40 of the first
and second encoders 10, 11.
[0231] In this example, a seal ring 104 is installed between a
space where plural rollers 103 of the conical roller bearing 29g
are located, and a space on the inside of the sensor cover 96 where
the first and second detected sections 39, 40 are arranged, and
functions as a seal device for partitioning between these spaces.
The seal ring 104 includes a circular ring-shaped metal core 105
having an L-shaped cross section, and a circular ring-shape seal
member 106 that is reinforced by the metal core 105. The metal core
105 fits around the outer-circumferential surface of the tip-end
section of the nut 32, which is a cylindrical surface, by an
interference fit, and the tip-end edge of the seal lip of the seal
member is made to come in contact with the inner-circumferential
surface of the base-end section of the extended cylindrical section
95, which is a cylindrical surface. As a result, lubrication oil
that includes foreign magnetic matters such as iron powder that is
supplied to the space where the conical rollers 75 are located is
prevented from passing through the portion between the
inner-circumferential surface of the extended cylindrical section
95 and the outer-circumferential surface of the tip-end section of
the nut 32b, and getting into the space inside the sensor cover 96.
By doing so, a drop in the reliability of the output signals from
the sensor unit 12 due to lubrication oil that includes foreign
magnetic matters such as iron powder is prevented from adhering to
the tip-end surfaces of the first and second encoders 10, 11, and
the sensor unit, and disturbance in the regular and periodic
magnetic change in the circumferential direction of the first and
second encoder 10, 11 is prevented. This kind of seal device is not
limited to this seal ring 104, and various forms can be used. For
example, it is also possible to use a seal member in which a metal
core fits around the inner-circumferential surface of the extended
cylindrical section 95, and the tip-end edge of the seal lip comes
in sliding contact with the surface of the nut 32b (or output shaft
14). In either case, using a seal device having good seal
characteristics, and for which the sliding resistance between the
tip-end edge of the seal lip and the opposing surface is kept low
is preferred.
[0232] In this example, the sensory unit 12d is fastened to and
supported by the outer ring 94 of a conical roller bearing 29c that
is installed between the output shaft 14 and the housing.
Therefore, when compared with construction in which the sensor unit
12 and the rotary-shaft unit 6 (see FIG. 6) that supports the first
and second encoders 10, 11 are separately fastened to and supported
by the housing, it is easier to maintain the positioning precision
of the sensor unit 12d with respect to the first and second
encoders 10, 11. Moreover, it is possible to assemble the sensor
unit 12d and rotary-shaft unit 6 in a specified positional
relationship before assembly inside the housing, and that
positional relationship does not move after that, so from this
aspect, maintaining positional precision becomes easier.
[0233] In this example, the first and second detected sections 39,
40 and the detecting sections of the first and second sensors 42a,
42b are arranged inside the sensor cover 96, and a seal ring 104 is
installed between the space inside the sensor cover 96 and the
space where the plural conical rollers 103 of the conical roller
bearing 29g are located so as to be a partition between these
spaces. Therefore, it is possible to suppress or prevent
lubrication oil that is inside the housing and that includes
magnetic foreign matter (including lubrication oil that is supplied
to the space where the conical rollers 103 are located) from
adhering to the first and second detected sections 39, 40 and the
detecting sections of the first and second sensors 42a, 42b. As a
result, it is possible to further improve the reliability of torque
measurement.
[0234] In this example, the first and second encoders 10, 11 are
housed in a space inside the sensor cover 96, so, for example, the
first and second encoders 10, 11 are prevented from bumping the
housing and becoming damaged when assembling the sensor unit 12d
and rotary-shaft unit 6 in the housing after the sensor unit 12d
and rotary-shaft unit 6 (see FIG. 6) have been assembled. Moreover,
in the stage before assembling portions other than the housing
inside the housing, it is possible to check the output signals of
the first and second sensors 42a, 42b. Furthermore, in the
completed state, even when there is deformation of the housing, it
is difficult for the positional relationship of the first and
second detected sections 39, 40 and the detecting sections of the
first and second sensors 42a, 42b to change. From this aspect as
well, it is possible to improve the reliability of the torque
measurement.
[0235] The rolling bearing for supporting the input shaft and
output shaft so as to freely rotate with respect to the housing is
not limited to a conical roller bearing, and it is also possible to
use other types of bearings such as an angular ball bearing. The
other construction and functions are the same as those of the first
through twenty-sixth examples of embodiments.
Twenty-Eighth Example
[0236] FIG. 61 illustrates a twenty-eighth example of an embodiment
of the present invention. In this example as well, the construction
of the installation location of the first and second encoders 10a,
11a is devised in order to improve the precision of torque
measurement. In other words, the inner ring 30h of a conical roller
bearing 20h for supporting the output shaft 14c so as to rotate
freely with respect to the housing is fastened around a portion
near the other end of the output shaft 14c, and the end surface on
the large-diameter side of the inner ring 30 is made to come in
contact with a stepped surface 33 that s formed in a portion near
the other end of the outer-circumferential surface of the output
shaft 14c. Then, in this state, the inner ring 30h is fastened
around the outside of the output shaft 14c by pressure fitting the
end surface on the small-diameter side of the inner ring 30h with a
nut 32c that is screwed onto the other end section of the
outer-circumferential surface of the output shaft 14c and
tightened. Particularly, in this example, a cylindrical shaped
extended cylindrical section 107 that protrudes in the axial
direction from the inner-diameter side of the outer ring 94a of the
conical roller bearing 29h is integrally provided on the end
section on the small-diameter side of the inner ring 30h, which is
the end section on the other end side of the output shaft 14c.
Moreover, a through hole 108 in the radial direction is provided in
a portion near the small-diameter side of the inner ring 30h.
Lubrication oil can be supplied from an oil passage 44b through
this through hole 108 to the inside of the conical roller bearing
29h.
[0237] In this example, the metal core 36a of the second encoder
11a is fastened around the outside of the extended cylindrical
section 107. In other words, the second encoder 11a is fastened
around the outside of a portion near the other end of the output
shaft 14c by way of the extended cylindrical section 107 of the
inner ring 30h. Moreover, the metal core 36a of the second encoder
11a is formed into a complete circular ring shape having a crank
shaped cross section, and includes a small-diameter cylindrical
section 109 and large-diameter cylindrical section 110 that are
arranged so as to be concentric with each other, and a ring section
111 that connects the edges on the ends in the axial direction of
these cylindrical sections 109, 110. A cylindrical shaped permanent
magnet 38a is fastened to the outer-circumferential surface of the
large-diameter cylindrical section 110. The second encoder is
fastened to the inner ring 30h by fastening the small-diameter
cylindrical section 109 of the metal core 36a around the outside of
the extended cylindrical section 107 of the inner ring 30h with an
interference fit. Moreover, in this state, the large-diameter
cylindrical section 110 and permanent magnet 38a are arranged on
the other-diameter side of half (right half in FIG. 61) in the
axial direction of the nut 32c in positions that overlap in the
radial direction with this half in the axial direction. In other
words, in this example, the cylindrical shaped second detected
section 40a, which is the outer-circumferential surface of the
permanent magnet 38a, is arranged on the outer-diameter side of
half in the axial direction of the nut 32c so as to overlap in the
radial direction this half in the axial direction (and other end
section of the output shaft 14c).
[0238] Moreover, the metal core 35a of the first encoder 10a is
formed into a complete circular ring shape with a C-shaped cross
section, and includes a small-diameter cylindrical section 112 and
a large-diameter section 113 that are arranged so as to be
concentric with each other, and a ring section 114 that connects
the end sections in the axial direction of these cylindrical
sections 112, 113. A cylindrical-shaped permanent magnet 37a is
fastened around the outer-circumferential surface of the
large-diameter cylindrical section 113. The small-diameter
cylindrical section 112 of the first encoder 10a is fastened around
the outside of the other end section (left-end section in FIG. 61)
of the coupling shaft 9. The connection between the
inner-circumferential surface of the small-diameter cylindrical
section 112 and the outer-circumferential surface of the other end
section of the coupling shaft 9 is formed by arranging a
cylindrical connection 26b for maintaining concentricity and an
involute spline connection 24e for preventing relative rotation so
as to be adjacently in contact with each other in the axial
direction. Moreover, the small-diameter cylindrical section 112 is
prevented from coming apart from the coupling shaft 9 by a
retaining ring 25d that is fastened around the
outer-circumferential surface of the other end section of the
coupling shaft 9. In this state, one end section (right-end section
in FIG. 61) and the middle section in the axial direction of the
large-diameter cylindrical section 113 and permanent magnet 37a are
arranged on the outer-diameter side of the other half (left half in
FIG. 61) in the axial direction of the nut 32c in positions that
overlap in the radial direction this other half in the axial
direction. In other words, in this example, one end section and
middle section in the axial direction of the cylindrical-shaped
first detected section 39a, which is the outer-circumferential
surface of the permanent magnet 37a, is arranged around the
outer-diameter side of the other half in the axial direction of the
nut 32c, in a position that overlaps in the radial direction the
other half section (or output shaft 14c) in the axial
direction.
[0239] As a result, the first detected section 39a and second
detected section 40a are adjacent in the axial direction and are
arranged close to each other (for example, arranged so as to be
separated by a space of 5 mm or less in the axial direction). The
sensor unit 12 is fastened to and supported by the housing so that
of the first and second sensor 42a, 42b of the sensor unit 12, the
detecting section of the first sensor 42a closely faces in the
radial direction the first detected section 39a, and the detecting
section of the second sensor 42b closely faces in the radial
direction the second detected section 40a.
[0240] In this example, the cylindrical shaped second detected
section 40a of the second encoder 11a is arranged around the
outer-diameter side of half in the axial direction of the nut 32c
so as to overlap in the radial direction that half in the axial
direction, so compared with the first example of an embodiment, it
is possible to shorten the distance D40 in the axial direction from
the center section in the axial direction of the array of rolling
bodies of the conical roller bearing 29h to the second detected
section 40a. Therefore, it is possible to keep displacement and
inclination in the radial direction of the second detected section
40a that occurs as the output shaft 14c bends about the conical
roller bearing 29h as a fulcrum due to the gear reaction force in
the radial direction that acts on the output gear 8 being applied
to the output shaft 14 when torque is being transmitted, small.
Furthermore, of the cylindrical shaped first detected section 39a
of the first encoder 10a that is fastened around the outside of the
other end section of the coupling shaft 9, the one end section to
middle section in the axial direction is arranged around the
outer-diameter side of the other half in the axial direction of the
nut 32c in a position that overlaps in the radial direction this
other half in the axial direction. Therefore, when compared with
the first example of an embodiment, it is possible to shorten the
distance D39 in the axial direction from the center section in the
axial direction of the array of rolling bodies of the conical
roller bearing 29h. Consequently, even when the coupling shaft 9
bends about the conical roller bearing 29h as a fulcrum due to gear
reaction force in the radial direction when torque is being
transmitted, it is possible to keep displacement and inclination in
the radial direction of the first detected section 39a that occurs
due to this bending, small.
[0241] Therefore, in this example, when compared with construction
in which the entire second detected section 40 of the second
encoder 11 that is fastened around the outside of the other end
section of the output shaft 14, and the entire first detected
section 39 of the first encoder 10 that is fastened around the
other end section of the coupling shaft 9 are arranged in a portion
that protrudes further toward the other side in the axial direction
than the other end section of the output shaft 14, such as in the
case of the first example of an embodiment, it is possible to
prevent contact between the first and second detected sections 39a,
40 and the tip-end surface of the sensor unit 12 even when the
space between the first and second detected sections 39a, 40a and
the tip-end surface of the sensor unit 12 is small, and regardless
of whether elastic deformation such as bending of the members
occurs due to gear reaction force in the radial direction that acts
when torque is being transmitted. Moreover, it is possible to
reduce shifting between the centers of rotation of the first and
second detected sections 39a, 40a that occurs due to displacement
or inclination in the radial direction of the first and second
detected sections 39a, 40a. As a result, when compared with the
case of the first example of an embodiment, it is possible to
further improve the precision of torque measurement.
[0242] In this example, from one end section to the middle section
in the axial direction of the first detected section 39a, and the
second detected section 40a are arranged around the outer-diameter
side of the nut 32c that is screwed onto and fastened the
outer-circumferential surface of the other end section of the
output shaft 14c in positions that overlap in the radial direction
with the nut 32c. Therefore, when compared with construction in
which the entire first and second detected sections 39, 40 are
arranged in a portion that protrudes further toward the other side
in the axial direction than the other end section of the output
shaft 14 such as in the first example of an embodiment, it is
possible to shorten the dimension in the axial direction of the
rotation transmission device. As a result, it is possible to make
the rotation transmission device more compact and lightweight. The
other construction and functions are the same as those of the first
through twenty-seventh examples of embodiments.
Twenty-Ninth Example
[0243] FIG. 62 to FIG. 65 illustrates a twenty-ninth example of an
embodiment of the present invention. In this example, the first and
second encoder 10e, 11e, and the sensor unit 12e are arranged in
the middle section of the rotary-shaft unit 6a, in a portion
between the input gear 7 and output gear 8 in the axial
direction.
[0244] In order for this, the first encoder 10e is integrally
formed on the tip-end surface (left-end surface in FIG. 62 and FIG.
65) of a parking-lock gear 28 that is integrally formed in a
portion near the inner circumference on one side surface of the
input gear 7. In other words, the first encoder 10e is formed by
arranging plural magnetic metal convex sections 50a that are
integrally formed so as to protrude in the axial direction from the
tip-end surface of the parking-lock gear 28 so as to have a uniform
pitch in the circumferential direction. The entire first encoder
10e functions as a first detected section 39e. The first encoder
10e is fastened to the input shaft 13 by way of the input gear 7
and parking-lock gear 28. Moreover, the second encoder 11e is
integrally formed with a portion that is near the
outer-circumferential surface of the output shaft 14, and that is
adjacent in the axial direction to the output gear 8. In other
words, the second encoder 11e is formed by arranging plural
magnetic metal convex sections 50b that are integrally formed so as
to protrude in the radial direction from a portion near on end of
the outer-circumferential surface of the output shaft 14 so as to
have a uniform pitch in the circumferential direction. The entire
second encoder 11e functions as a second detected section 40e. In
this example, the first and second encoders 10e, 11e have the same
outer-diameter dimensions, and are arranged so as to be concentric
with each other and so as to be closely adjacent to each other in
the axial direction. The total number of convex sections 50a and
the total number of convex sections 50b are the same as each other.
Moreover, the width in the circumferential direction of the convex
sections 50a and the width in the circumferential direction of the
convex sections 50b are the same as each other. Furthermore, when
torque is not being transmitted, the phases in the circumferential
direction of the convex sections 50a and convex sections 50b
coincide.
[0245] The sensor unit 12e includes a holder 41c that is made of a
synthetic resin, and first and second sensors 42e, 42f that are
embedded in the tip-end sections of the holder 41c. The sensor unit
12e is supported by a housing (not illustrated in the figures) so
that the detecting section of the first sensor 42e closely faces
the outer-circumferential surface of the first encoder 10e (first
detected section 39e), and the detecting section of the second
sensor 42f closely faces the outer-circumferential surface of the
second encoder 11e (second detected section 40e). Each of the
sensors 42e, 42f includes a permanent magnet that is magnetized in
the direction that the outer-circumferential surface of the encoder
10e, 11e faces the detecting section of the sensor 42e, 42f; and a
magnetism-detecting element such as a Hall element, Hall IC, MR
element, GMR element or the like that is located in the end surface
of both end surfaces in the direction of magnetization of the
permanent magnet. One permanent magnet can also be shared as the
permanent magnet of the sensors 42e, 42f.
[0246] In this example, there is no coupling shaft on the
inner-diameter side of the torsion bar 15c. An oil inlet passage
43a that is on only one end surface is provided in the center
section in the radial direction of the torsion bar 15c. In this
example, lubrication oil that enters inside the oil inlet passage
43a through the opening on one end section of the oil inlet passage
43a is supplied to the inside of a pair of oil passages 44a, 44b
that are provided in portions near both ends of the rotary-shaft
unit 6a.
[0247] In this example, as in the first example of an embodiment,
the frequency (and period) of the output signals from the first and
second sensors 42e, 42f of the sensor unit 12e is a value that
corresponds to the rotational speed of the rotary-shaft unit 6a.
Therefore, it is possible to find the rotational speed based on the
frequency (or period). Moreover, the phase difference ratio (=phase
difference/1 period) between the output signals of the first and
second sensors 42e, 42f is a value that corresponds to the torque
that is transmitted by the rotary-shaft unit 6a between the input
gear 7 and the output gear 8. Therefore, it is possible to find the
torque based on this phase difference ratio. The other construction
and functions are the same as those of the first example of an
embodiment.
[0248] When embodying the construction of each of the examples of
embodiments described above, as long as there are no evident
contradictions in the construction, it is possible to freely
combine the construction of the examples of embodiments.
INDUSTRIAL APPLICABILITY
[0249] The form of a transmission in which the present invention is
assembled and used is not particularly limited as long as the
construction has a counter shaft and a counter gear, and it is
possible to use various kinds of transmissions such as an automatic
transmission (AT), continuously-variable transmission (CVT), manual
transmission (MT) and the like. Moreover, the rotational speed and
torque that are measured can be used for other control of an
automobile besides transmission control. Furthermore, a motor that
is placed on the up-stream side of the transmission does not
absolutely need to be an internal-combustion engine such as a
gasoline engine or a diesel engine, and it is also possible for the
motor to be an electric motor that is used, for example, in a
hybrid automobile or an electric automobile. In either case,
present invention can be widely applied to various kinds of
machinery in which it is necessary to transmit torque by a rotary
shaft, and to measure the torque that is transmitted by the rotary
shaft.
[0250] Furthermore, when embodying the present invention, it is
necessary to measure the torque, however, except for construction
in which voltage is generated in a coil (when using an induced
electromotive force), it is not necessary to measure the rotational
speed. Even when knowing the rotational speed is necessary, it is
possible to measure that rotational speed by using separate and
simple construction.
EXPLANATION OF REFERENCE NUMBERS
[0251] 1 Rotary shaft [0252] 2, 2a Encoder [0253] 3 Sensor [0254] 4
Harness [0255] 5 Sensor unit [0256] 6, 6a Rotary-shaft unit [0257]
7 Input gear [0258] 8 Output gear [0259] 9, 9a, 9b Coupling shaft
[0260] 10, 10a to 10h First encoder [0261] 11, 11a to 11h Second
encoder [0262] 12, 12a to 12e Sensor unit [0263] 13, 13a to 13c
Input shaft [0264] 14, 14a to 14c Output shaft [0265] 15, 15a to
15c Torsion bar [0266] 16 Input-side combination cylinder [0267] 17
Output-side combination cylinder [0268] 18 Radial needle bearing
[0269] 19 Stepped surface [0270] 20 Tip-end surface [0271] 21, 21a
to 21c Thrust washer [0272] 22 Slit [0273] 23 Reinforcing
cylindrical section [0274] 24a to 24e, 24a1, 24b1 Involute spline
connection [0275] 25a to 25d Retaining ring [0276] 26a, 26b
Cylindrical connecting section [0277] 27 Stepped surface [0278] 28
Packing-lock gear [0279] 29a to 29h Conical roller bearing [0280]
30a to 30h Inner ring [0281] 31 Spacer [0282] 32a to 32c Nut [0283]
33 Stepped surface [0284] 34 Rim section [0285] 35, 35a, 35b Metal
core [0286] 36, 36a, 36b Metal core [0287] 37, 37a to 37c Permanent
magnet [0288] 38, 38a to 38c Permanent magnet [0289] 39, 39a to 39e
First detected section [0290] 40, 40a to 40e Second detected
section [0291] 41, 41a to 41c Holder [0292] 42a to 42f (First,
Second) Sensor [0293] 43, 43a Oil inlet passage [0294] 44a, 44b Oil
passage [0295] 45a, 45b Ring-shaped space [0296] 46a, 46b Oil
groove [0297] 47 Cylindrical space [0298] 48 Tip-end surface [0299]
49 Stepped surface [0300] 50, 50a, 50b Convex section [0301] 51,
51a to 51d Tongue piece [0302] 52 Stator [0303] 53 Conducting wire
[0304] 54 Coil [0305] 55 Core [0306] 56 Rim section [0307] 57
Sleeve bearing [0308] 58 Thrust needle bearing [0309] 59 Pin [0310]
60 Engagement hole [0311] 61 Oil passage [0312] 62, 62a First male
involute spline section [0313] 63, 63a First male involute spline
section [0314] 64, 64a Second female involute spline section [0315]
65, 65a Second female involute spline section [0316] 66a, 66b
Concave groove [0317] 67a, 67b Through hole [0318] 68 Concave hole
[0319] 69 Pin [0320] 70a, 70b Concave section [0321] 71 Convex
section [0322] 72a, 72b Marking [0323] 73a, 73b Marking [0324] 74
First plating layer [0325] 75 Second plating layer [0326] 76
Cylindrical surface [0327] 77 Cylindrical surface [0328] 78 Tube
section [0329] 79 Inclined surface section [0330] 80 First fastener
[0331] 81 Second fastener [0332] 82 Input-side rotating body [0333]
83 Input-side unit [0334] 84 Output-side rotating body [0335] 85
Output-side unit [0336] 86 Stepped surface [0337] 87 Fitting
cylindrical section [0338] 88 Ring section [0339] 89 Cylindrical
section [0340] 90 Large-diameter section [0341] 91 Sliding bearing
[0342] 92 Small-diameter section [0343] 93 Large-diameter section
[0344] 94, 94a Outer ring [0345] 95 Extended cylindrical section
[0346] 96 Sensor cover [0347] 97 Sensor holder [0348] 98 Cover
cylinder section [0349] 99 Cover bottom plate section [0350] 100
Rim section [0351] 101 Through hole [0352] 102 Connector section
[0353] 103 Conical roller [0354] 104 Seal ring [0355] 105 Metal
core [0356] 106 Seal ring [0357] 107 Extended cylindrical section
[0358] 108 Through hole [0359] 109 Small-diameter cylindrical
section [0360] 110 Large-diameter cylindrical section [0361] 111
Ring section [0362] 112 Small-diameter cylindrical section [0363]
113 Large-diameter cylindrical section [0364] 114 Ring section
[0365] 115, 115a Spring section
* * * * *