U.S. patent application number 11/679183 was filed with the patent office on 2007-09-13 for torque sensor.
Invention is credited to Hideo MAEHARA.
Application Number | 20070209450 11/679183 |
Document ID | / |
Family ID | 38123943 |
Filed Date | 2007-09-13 |
United States Patent
Application |
20070209450 |
Kind Code |
A1 |
MAEHARA; Hideo |
September 13, 2007 |
TORQUE SENSOR
Abstract
A magnetism generation portion 4 is provided at a first shaft 2,
and a first magnetic yoke 7 and a second magnetic yoke 8 bent in L
shape are provided at a second shaft 3 so that a magnetic flux
generated at the magnetism generation portion 4 can be detected on
the outer circumference side of the second shaft 3, and a magnetism
detecting device for detecting the magnetic flux can be provided on
the outer circumference side of the second shaft.
Inventors: |
MAEHARA; Hideo; (Kani-shi,
JP) |
Correspondence
Address: |
Michael L. Crapenhoft;c/o Hiroe & Associates
4-3 Usa 3-chome
Gifu City
500-8368
omitted
|
Family ID: |
38123943 |
Appl. No.: |
11/679183 |
Filed: |
February 27, 2007 |
Current U.S.
Class: |
73/862.332 |
Current CPC
Class: |
G01L 5/221 20130101;
B62D 6/10 20130101; G01L 3/104 20130101 |
Class at
Publication: |
73/862.332 |
International
Class: |
G01L 3/00 20060101
G01L003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 13, 2006 |
JP |
2006-67355 |
Claims
1. A torque sensor comprising a housing, a first shaft and a second
shaft accommodated in the housing and connected coaxially by a
torsion bar, and a magnetism generation portion attached to the
first shaft so as to surround the outer circumference of the first
shaft and outputting a magnetic flux in the axis core direction of
the first shaft, in which a plurality of magnetic yoke portions
comprising a first magnetic yoke and a second magnetic yoke for
guiding the magnetic flux outputted from the magnetism generation
portion are attached to the second shaft; and a torque between the
first shaft and the second shaft is detected magnetically by a
magnetic sensor through detection of the magnetic flux in a
magnetic gap between the first magnetic yoke and the second
magnetic yoke, wherein the first magnetic yoke and the second
magnetic yoke have their one end opposed to the magnetism
generation portion, respectively, and the first magnetic yoke and
the second magnetic yoke are bent in the L shape in the middle and
extended in the direction crossing the axis core of the second
shaft, respectively, and the other ends of the first magnetic yoke
and the second magnetic yoke are provided separately from each
other in the axis core direction on the outer circumference side of
the second shaft; the other ends of the first magnetic yokes of
each magnetic yoke portion are connected to each other by a first
magnetic ring; the other ends of the second magnetic yokes of each
magnetic yoke portion are connected to each other by a second
magnetic ring; and the magnetic sensor is provided in the magnetic
gap between the first magnetic ring and the second magnetic
ring.
2. The torque sensor, wherein a first magnetism collecting ring is
provided opposite to the first magnetic ring in the housing; a
second magnetism collecting ring is provided opposite to the second
magnetic ring in the housing; and a magnetic gap forming portion
for forming the magnetic gap is provided between the first
magnetism collecting ring and the second magnetism collecting
ring.
3. The torque sensor according to claim 2, wherein the first
magnetism collecting ring is provided wider than the first magnetic
ring and the second magnetism collecting ring is provided wider
than the second magnetic ring.
4. The torque sensor according to claim 2 or 3, wherein the
magnetic gap forming portion is provided with a first magnetism
collecting yoke connected to the first magnetism collecting ring, a
second magnetism collecting yoke connected to the second magnetism
collecting ring, and two pairs of projections provided at the first
magnetism collecting yoke and the second magnetism collecting yoke,
wherein each magnetic gap is made between these two pairs of the
projections and each magnetic sensor is provided in each magnetic
gap.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a torque sensor suitable
for use in a power steering device.
[0002] FIGS. 9 to 12 show a construction of a torque sensor 100 of
a conventional art (shown in Patent Document 1, for example). FIG.
9 is a perspective view in the vicinity of the torque sensor. FIG.
10 is a partially enlarged view of FIG. 9. FIGS. 11 and 12 are
diagrams for explaining the action.
[0003] [Patent Document 1] Patent No. 3094049
[0004] In FIG. 9, the torque sensor 100 is provided between a first
shaft 101 and a second shaft 102. At the first shaft 101, a
magnetism generation portion 103 for outputting a magnetic flux is
provided. The magnetism generation portion 103 has a plurality of
magnets 104 provided in the circumferential direction around the
first shaft 101. The magnets 104 are magnetized toward the axis
core direction (arrow direction) of the first shaft 101 and the
adjoining magnets 104 are magnetized in the direction opposite to
each other, and thus, when the magnetism generation portion 103 is
seen from the second shaft 102 side, as shown in FIG. 10, magnetic
poles different from each other are adjoined. That is, S poles and
N poles are arranged alternately.
[0005] As shown in FIG. 9, the second shaft 102 is provided with an
outer ring 105 and an inner ring 106, and as shown in FIG. 10, a
plurality of outer magnetic path pieces 107 are extended from the
outer ring 105, while inner magnetic path pieces 108 are extended
from the inner ring 106. As shown in FIG. 10, a clearance 109 is
provided between the outer ring 105 and the inner ring 106, and a
magnetic sensor 110 is arranged in the clearance 109.
[0006] Next, action will be described. Suppose that a driver does
not steer a steering wheel. In this case, since the first shaft 101
is not rotated with respect to the second shaft 102, as shown in
FIG. 11, each outer magnetic path piece 107 is opposed to the N
pole and the S pole of the magnet 104 over the same area each, and
each inner magnetic path piece 108 is similarly opposed to the N
pole and the S pole of the magnet 104 over the same area each. In
this case, the magnetic flux is not guided to the outer magnetic
path piece 107 and the inner magnetic path piece 108, and the
magnetic flux outputted from the N pole of the magnet 104 is
inputted to the S pole of the magnet 104. Therefore, the magnetic
flux sensor 110 does not detect the magnetic flux.
[0007] Next, suppose that the driver has steered the steering
wheel. In this case, the first shaft 101 is rotated with respect to
the second shaft 102, and as shown in FIG. 12, the outer magnetic
path piece 107 is moved to the S pole side, while the inner
magnetic path piece 108 is moved to the N pole side. In this case,
since the magnetic flux outputted from the N pole of the magnet 104
reaches the S pole of the magnet 104 via the inner magnetic path
piece 108, the inner ring 106, the magnetic sensor 110, the outer
ring 105, and the outer magnetic path piece 107, a rotation amount
of the first shaft 101 with respect to the second shaft 102, that
is, a steering torque of the steering wheel can be detected based
on the magnetic flux amount detected by the magnetic sensor
110.
[0008] In the above-mentioned background art, since the torque
sensor 100 is in the structure that it is provided between the
first shaft 101 and the second shaft 102 in the axial direction,
the entire length is long in the axial direction due to a space in
which the torque sensor 100 is arranged. Thus, the torque sensor
100 which can be accommodated in the compact manner in the axial
direction has been in demand.
[0009] The present invention was made in view of the problems of
the background art and has an object to provide a torque sensor
which can reduce the length in the axial direction when it is
attached to two shafts whose torque is to be detected.
SUMMARY OF THE INVENTION
[0010] The present invention is a torque sensor comprising a
housing, a first shaft and a second shaft accommodated in the
housing and connected coaxially by a torsion bar, and a magnetism
generation portion attached to the first shaft so as to surround
the outer circumference of the first shaft and outputting a
magnetic flux in the axis core direction of the first shaft, in
which
[0011] a plurality of magnetic yoke portions comprising a first
magnetic yoke and a second magnetic yoke for guiding the magnetic
flux outputted from the magnetism generation portion are attached
to the second shaft; and
[0012] a torque between the first shaft and the second shaft is
detected magnetically by a magnetic sensor through detection of the
magnetic flux in a magnetic gap between the first magnetic yoke and
the second magnetic yoke,
[0013] wherein the first magnetic yoke and the second magnetic yoke
have their one end opposed to the magnetism generation portion,
respectively, and the first magnetic yoke and the second magnetic
yoke are bent in the L shape in the middle and extended in the
direction crossing the axis core of the second shaft, respectively,
and the other ends of the first magnetic yoke and the second
magnetic yoke are provided separately from each other in the axis
core direction on the outer circumference side of the second
shaft;
[0014] the other ends of the first magnetic yokes of each magnetic
yoke portion are connected to each other by a first magnetic
ring;
[0015] the other ends of the second magnetic yokes of each magnetic
yoke portion are connected to each other by a second magnetic ring;
and
[0016] the magnetic sensor is provided in the magnetic gap between
the first magnetic ring and the second magnetic ring.
[0017] According to the present invention, since it is so
constructed that the magnetic flux outputted from the magnetism
generation portion is guided outward in the radial direction of the
shaft so that change in the magnetic flux with change of a steering
torque of a steering wheel is detected on outside in the radial
direction of the shaft, a magnetism detecting device provided with
a magnetic sensor can be arranged outside in the radial direction
of the shaft and the construction can be formed with compact length
in the axial direction.
DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a view showing the principle of the present
invention;
[0019] FIG. 2 is a diagram for explaining action;
[0020] FIG. 3 is a diagram for explaining action;
[0021] FIG. 4 is an end face view in a state where a first magnetic
yoke, a second magnetic yoke, a first magnetic ring and a second
magnetic ring are molded to a resin and a sleeve is assembled
thereto;
[0022] FIG. 5 is an A-A sectional view of FIG. 2;
[0023] FIG. 6 is a B-B sectional view of FIG. 2;
[0024] FIG. 7 is a C-C sectional view of FIG. 2;
[0025] FIG. 8 is a longitudinal sectional view of an electric power
steering device;
[0026] FIG. 9 is a perspective view of the vicinity of a torque
sensor (conventional art);
[0027] FIG. 10 is a partial enlarged view of FIG. 7 (conventional
art);
[0028] FIG. 11 is a diagram for explaining action (conventional
art); and
[0029] FIG. 12 is a diagram for explaining action (conventional
art).
DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS
[0030] A principle of the present invention will be described based
on the attached drawings. FIG. 1 explains an example used when a
torque sensor 1 of the present invention is applied to an electric
power steering device for detecting a torque between an input shaft
2 and an output shaft 3. The input shaft 2 and the output shaft 3
are stored in a housing H.
[0031] To the input shaft 2, a steering force is given by the
steering wheel. The output shaft 3 gives a steering assisting force
to the steered system side. The input shaft 2 and the output shaft
3 are connected to each other by a torsion bar.
[0032] At the input shaft 2, a magnetism generation portion 4 is
provided. The magnetism generation portion 4 is in the structure
that a magnet portion 6 is provided at a back yoke 5 formed by an
annular magnetic body. The magnet portion 6 is formed by
magnetizing the magnetic body toward the axis core direction of the
input shaft 2 and in the circumferential direction, it is
magnetized so that N poles and S poles are arranged alternately as
shown in FIG. 1.
[0033] At the output shaft 3, a magnetic yoke portion 9 constructed
by a first magnetic yoke 7 and a second magnetic yoke 8 are
provided. The magnetic yoke portion 9 is provided on the outer
circumference of the output shaft 3 in plural toward the
circumferential direction. The first magnetic yoke 7 is formed by a
straight portion 10 and a crossing portion 11 crossing the straight
portion 10 and bent in the L shape. The straight portion 10 of the
first magnetic yoke 7 is provided along the axial direction, and
one end of the first magnetic yoke 7 is faced with the magnet
portion 6. Also, the crossing portion 11 of the first magnetic yoke
7 is provided in the radial direction, while the other end of the
first magnetic yoke 7 is faced outward in the radial direction of
the output shaft 3.
[0034] Also, the second magnetic yoke 8 is formed by a straight
portion 12 and a crossing portion 13 crossing the straight portion
12 and bent in the L shape. The straight portion 12 of the second
magnetic yoke 8 is provided along the axial direction, and one end
of the second magnetic yoke 8 is faced with the magnet portion 6.
Also, the crossing portion 13 of the second magnetic yoke 8 is
provided in the radial direction, while the other end of the second
magnetic yoke 7 is faced outward in the radial direction of the
output shaft 3. The other end of the first magnetic yoke 7 and the
other end of the second magnetic yoke 8 are separated from each
other in the axis core direction of the output shaft 3.
[0035] The other ends of the first magnetic yokes 7 of each
magnetic yoke portion 9 are connected to each other by a first
magnetic ring 14, while the other ends of the second magnetic yokes
8 of each magnetic yoke portion 9 are connected to each other by a
second magnetic ring 15.
[0036] Outside the first magnetic ring 14, a first magnetism
collecting ring 17 is provided on the inner surface of the housing
H so as to surround the first magnetic ring 14. The magnetism
collecting ring 17 is formed by a magnetic body and constitutes a
part of a magnetic circuit. The first magnetism collecting ring 17
is in the shape that a plate material is bent in an annular state.
The width in the axial direction of the first magnetism collecting
ring 17 is formed larger than the width in the axial direction of
the first magnetic ring 14. Also, outside the second magnetic ring
15, a second magnetism collecting ring 18 is provided on the inner
surface of the housing H so as to surround the second magnetic ring
15. The second magnetism collecting ring 18 is formed by a magnetic
body and constitutes a part of the magnetic circuit. The second
magnetism collecting ring 18 is in the shape that a plate material
is bent in the annular state. The width in the axial direction of
the second magnetism collecting ring 18 is formed larger than the
width in the axial direction of the second magnetic ring 15.
[0037] A first magnetism collecting yoke 19 is provided at the
first magnetism collecting ring 17, while a second magnetism
collecting yoke 20 is provided at the second magnetism collecting
ring 18. At the first magnetism collecting yoke 19 and the second
magnetism collecting yoke 20, two pairs of projections 21, 22, 23,
24 are provided so that they are opposed to each other. A magnetic
gap is formed between each pair of projections 21, 22, 23, 24, and
magnetic sensors 25, 26 are arranged in the magnetic gaps. A
magnetic gap forming portion is constructed by the first magnetism
collecting yoke 19, the second magnetism collecting yoke 20, the
pairs of projections 21, 22, 23, 24.
[0038] Next, action will be described. In the state where the
steering wheel is not steered, as shown in FIG. 2, the centers of
one ends of the first magnetic yoke 7, the second magnetic yoke 8
are located at the boundary between the N pole and the S pole with
each one end extending over the N pole and the S pole of the magnet
portion 6 so that each one end is faced with the N pole and the S
pole by the same area.
[0039] As shown in FIG. 2, in this state, the magnetic flux
outputted from the N pole is not guided by the first magnetic yoke
7 and the second magnetic yoke 8 but inputted to the S pole of the
magnet portion 6. Therefore, the magnetic sensors 25, 26 shown in
FIG. 1 do not detect the magnetic flux.
[0040] Next, suppose that the driver steers the steering wheel. In
this case, since the input shaft 2 is rotated with respect to the
output shaft 3, as shown in FIG. 3, the center of one end of the
first magnetic yoke 7 is moved to the N pole side, the area of the
one end facing the N pole of the magnet portion 6 becomes larger
than the area facing the S pole of the magnet portion 6. Also, the
center of one end of the second magnetic yoke 8 is moved to the S
pole side and the area of the one end facing the S pole of the
magnet portion 6 becomes larger than the area facing the N pole of
the magnet portion 6. In this case, in the first magnetic yoke 7,
after the magnetic flux outputted from the N pole of the magnet
portion 6 is inputted, the magnetic flux goes through a magnetic
circuit of the first magnetic ring 14, the first magnetism
collecting ring 17, the first magnetism collecting yoke 19, the
projections 22, 24, the magnetic sensor 25, 26, the projections 21,
23, the second magnetism collecting yoke 20, the second magnetism
collecting ring 18, the second magnetic ring 15, the second
magnetic yoke 8 to the S pole of the magnet portion 6 as shown in
FIG. 1.
[0041] The amount of the magnetic flux detected at the magnetic
sensors 25, 26 corresponds to the area of the one end of the first
magnetic yoke 7 facing the N pole of the magnet portion 6 and the
area of the one end of the second magnetic yoke 8 facing the S pole
of the magnet portion 6. Therefore, from the amount of the magnetic
flux detected at the magnetic sensors 25, 26, movement amounts of
the first magnetic yoke 7 and the second magnetic yoke 8, that is,
the steering torque of the steering wheel rotating the input shaft
2 can be detected.
[0042] In this way, since the first magnetic yoke 7 and the second
magnetic yoke 8 are bent in the L shape so that they can guide the
magnetic flux outputted from the magnetism generation portion 4 to
the outer circumference side of the output shaft 3 and a magnetism
detecting device provided with the magnetic sensors 25, 26 can be
provided on the outer circumference side of the output shaft 3, the
length of the input shaft 2 and the output shaft 3 in the axial
direction can be formed short.
[0043] Also, the first magnetism collecting ring 17, the second
magnetism collecting ring 18 are provided facing the first magnetic
ring 14, the second magnetic ring 15 outside each of the first
magnetic ring 14, the second magnetic ring 15 so as to surround the
first magnetic ring 14, the second magnetic ring 15. Therefore,
even if the first magnetic ring 14 and the second magnetic ring 15
are eccentric with each other, all the magnetic fluxes passing
through the first magnetic ring 14 and the second magnetic ring 15
can be efficiently guided to the first magnetism collecting ring 17
and the second magnetism collecting ring 18. Moreover, since the
first magnetism collecting ring 17 and the second magnetism
collecting ring 18 are formed wider in the axial direction than the
first magnetic ring 14 and the second magnetic ring 15,
respectively, the magnetic flux having passed through the first
magnetic ring 14 and the second magnetic ring 15 are more
efficiently guided to the first magnetism collecting ring 17 and
the second magnetism collecting ring 18.
[0044] Also, the first magnetism collecting ring 17 and the second
magnetism collecting ring 18 are formed wider than the first
magnetic ring 14 and the second magnetic ring 15 respectively,
outside the first magnetic ring 14 and the second magnetic ring 15,
respectively. Therefore, even if there is an error of positional
displacement in the direction along the axis core between the first
magnetic ring 14 and the first magnetism collecting ring 17 as well
as the second magnetic ring 15 and the second magnetism collecting
ring 18, the first magnetism collecting ring 17 can be faced with
the first magnetic ring 14, and the second magnetism collecting
ring 18 can be faced with the second magnetic ring 15. Therefore, a
loss of the magnetic flux between the first magnetism collecting
ring 17 and the first magnetic ring 14 as well as the second
magnetic collecting ring 18 and the second magnetic ring 15 can be
suppressed, and efficient transmission is achieved.
[0045] Also, the magnetic flux outputted from the N pole of the
magnet portion 6 faced with the first magnetic yoke 7 goes through
the plurality of first magnetic yokes 7, the first magnetic ring
14, the first magnetism collecting ring 17, the second magnetism
collecting ring 18, the second magnetic ring 15, the plurality of
second magnetic yokes 8 and in the middle of the way to the S pole
of the magnet portion 6 faced with the second magnetic yoke 8, it
goes through the magnetic sensors 25, 26, being concentrated with a
high density between the projections 22, 24 of the first magnetism
collecting yoke 19 and the projections 21, 23 of the second
magnetism collecting yoke 20. Thus, the magnetic sensors 25, 26 can
detect change in the magnetic flux with operation of the steering
wheel efficiently and with high accuracy.
[0046] FIGS. 4 to 7 show a sleeve assembly 32 in which a sleeve 31
is provided at a yoke mold body 30 where the first magnetic yoke 7,
the second magnetic yoke 8, the first magnetic ring 14 and the
second magnetic ring 15 are molded to a resin. FIG. 4 shows an end
face view of the sleeve assembly 32, FIG. 5 shows an A-A sectional
view of FIG. 4, FIG. 6 is a B-B sectional view of FIG. 4 and FIG. 7
is a C-C sectional view of FIG. 4.
[0047] As shown in FIGS. 5 to 7, the sleeve 31 is in the shape
inserted into the yoke mold body 30 from the tip end side and the
rear end side of the sleeve 31 is constructed so that the yoke mold
body 30 is exposed to the outside. The sleeve 31 is, as will be
described later, press-fitted into the output shaft 3 when the
sleeve assembly 32 is assembled to the output shaft 3.
[0048] As mentioned above, since a resin is not provided on the
outer circumference of the rear end side of the sleeve 31, there is
no fear that the resin is damaged even if the diameter of the
sleeve 31 is expanded at press fitting of the sleeve 31 into the
output shaft 3, and moreover, the force to expand the diameter of
the sleeve 31 is rarely left as a stress in the resin.
[0049] In the above embodiment shown in FIG. 1, the desired object
of the present invention can be achieved even after the first
magnetism collecting ring 17, the second magnetism collecting ring
18, the first magnetism collecting yoke 19 and the second magnetism
collecting yoke 20 are deleted, a space between the first magnetic
ring 14 and the second magnetic ring 15 is made as a magnetic gap
and the magnetic sensors 25, 26 are provided in the magnetic
gap.
[0050] However, when it is constructed as in the above described
manner in the embodiment shown in FIG. 1, the following working
effect is exerted. When the first magnetism collecting ring 17, the
second magnetism collecting ring 18 are not provided but the
magnetic gap is provided between the first magnetic ring 14 and the
second magnetic ring 15 so as to detect the magnetic flux in the
magnetic gap by the magnetic sensors 25, 26, if the first magnetic
ring 14 and the second magnetic ring 15 are not assembled in
parallel with each other with high accuracy, an interval of the
magnetic gap is changed due to change in the width of the clearance
between the first magnetic ring 14 and the second magnetic ring 15
with rotation of the input shaft 2 and the output shaft 3,
detection of the magnetic flux is affected. That is, due to
influence of an error in assembling of the first magnetic ring 14
and the second magnetic ring 15, magnetic detection of the rotation
of the output shaft 3 with respect to the input shaft 2 with
accuracy becomes difficult.
[0051] On the other hand, in the above embodiment shown in FIG. 1,
outside the first magnetic ring 14 and the second magnetic ring 15,
the first magnetism collecting ring 17 and the second magnetism
collecting ring 18 are provided in the housing H, respectively, the
first magnetism collecting yoke 19 and the second magnetism
collecting yoke 20 are provided at the first magnetism collecting
ring 17 and the second magnetism collecting ring 18, and two pairs
of projections 21 to 24 are provided at the first magnetism
collecting yoke 19 and the second magnetism collecting yoke 20 so
that spaces between these two pairs of the projections 21 to 24 are
made as the magnetic gaps, and the first magnetism collecting ring
17 and the second magnetism collecting ring 18 are mounted to the
housing H and fixed. Therefore, the interval of the magnetic gap is
not affected by rotation of the input shaft 2 and the output shaft
3 but constant. That is, in the case of the above embodiment shown
in FIG. 1, not affected by the rotation of the input shaft 2 and
the output shaft 3, detection can be made while reducing an error
of the steering force of the steering wheel.
[0052] FIG. 8 shows a longitudinal sectional view of an electric
power steering device 40 incorporating the above torque sensor 1.
In the housing H, the input shaft 2 and the output shaft 3 are
arranged vertically, and the input shaft 2 and the output shaft 3
are rotatably supported in the housing H by bearings 41, 42. The
input shaft 2 is formed in the cylindrical shape, and a torsion bar
43 is arranged inside. The torsion bar 43 is connected to the input
shaft 2 by a pin 44 at the upper end.
[0053] The lower end side of the torsion bar 43 is connected to the
output shaft 3 through a serration 44.
[0054] To the input shaft 2, the magnetism generation portion 4 is
mounted. The magnetism generation portion 4 is provided with a back
yoke 46 formed with a shaft insertion hole 45 at the center and
formed from an annular magnetic body and the magnet portion 6
attached to the back yoke 46. The back yoke 46 is a member formed
from a magnetic body and functioning as a magnetic path.
[0055] Also, at the output shaft 3, the sleeve assembly 32 is
press-fitted and mounted. The sleeve assembly 32 is assembled to
the upper end of the output shaft 3 so that the sleeve 31 is
press-fitted to the upper end of the output shaft 3. The sleeve 31
is formed by a non-magnetic body so that the magnetic flux
generated at the magnetism generation portion 4 does not leak to
the output shaft 3 side.
[0056] As shown in FIG. 8, in the state where the sleeve assembly
32 is assembled to the output shaft 3, one ends of the first
magnetic yoke 7 and the second magnetic yoke 8 are faced with the
magnet portion 6 of the magnetism generation portion 4 with a
slight gap between them.
[0057] On the inner face of the housing H, the first magnetism
collecting ring 17 and the second magnetism collecting ring 18 are
attached. The first magnetism collecting ring 17 is formed wider
than the first magnetic ring 14 and faced with the first magnetic
ring 14. The second magnetism collecting ring 18 is formed wider
than the second magnetic ring 15 and faced with the second magnetic
ring 15.
[0058] In the housing H, a magnetism detecting device mounting hole
47 is formed, and a magnetism detecting device 48 is attached to
the magnetism detecting device mounting hole 47. The magnetism
detecting device 48 is provided with the magnetic sensors 25, 26
and incorporates a calculation portion and the like for calculating
a magnetic flux amount based on the outputs of the magnetic sensors
25, 26.
[0059] In the magnetism detecting device mounting hole 47, the
first magnetism collecting yoke 19 is mounted to the first
magnetism collecting ring 17. Also, the second magnetism collecting
yoke 20 is mounted to the second magnetism collecting ring 18. At
the first magnetism collecting yoke 19 and the second magnetism
collecting yoke 20, the projections 21, 23, 22, 24 (shown in FIG.
1) are provided so that they are opposed to each other. Between the
projections 21, 23, 22, 24 opposed to each other, the magnetic
sensors 25, 26 are arranged.
[0060] In the above description, the case where the torque sensor 1
is applied to the electric power steering device 40 has been
described, but not limited to the electric power steering device
40, it can be widely applied for detection of a torque between two
shafts.
* * * * *