U.S. patent application number 14/125178 was filed with the patent office on 2015-03-12 for electric position adjustment apparatus for steering wheel.
The applicant listed for this patent is NSK Ltd.. Invention is credited to Masato Iwakawa, Hiroshi Kakita, Yoshiyuki Sekii.
Application Number | 20150069745 14/125178 |
Document ID | / |
Family ID | 49623876 |
Filed Date | 2015-03-12 |
United States Patent
Application |
20150069745 |
Kind Code |
A1 |
Iwakawa; Masato ; et
al. |
March 12, 2015 |
Electric Position Adjustment Apparatus for Steering Wheel
Abstract
In order to make it possible to stably and smoothly perform the
operation of position adjustment of a steering wheel 1, the
electric position adjustment apparatus for a steering wheel of the
present invention is such that: a concave engaging section 19a of a
moving piece 16a that moves in the forward/backward direction with
an electric motor 56 as a driving source has a cylindrical
concave-shaped inner-circumferential surface; a cylindrical column
section 65 of a transmission member 17a that transmits the movement
of the moving piece 16a to a steering column 5b is inserted into
the concave engaging section 19a by way of cylindrical spacer 72
and has a cylindrical convex-shaped outer-circumferential surface;
and a cylindrical spacer 72 has a cylindrical convex-shaped
outer-circumferential surface and a cylindrical concave-shaped
inner-circumferential surface.
Inventors: |
Iwakawa; Masato;
(Maebashi-shi, JP) ; Sekii; Yoshiyuki;
(Maebashi-shi, JP) ; Kakita; Hiroshi;
(Maebashi-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NSK Ltd. |
Shinagawa-ku, Tokyo |
|
JP |
|
|
Family ID: |
49623876 |
Appl. No.: |
14/125178 |
Filed: |
May 22, 2013 |
PCT Filed: |
May 22, 2013 |
PCT NO: |
PCT/JP2013/064282 |
371 Date: |
December 10, 2013 |
Current U.S.
Class: |
280/775 |
Current CPC
Class: |
B62D 1/189 20130101;
B62D 1/187 20130101; B62D 1/181 20130101; B62D 1/185 20130101 |
Class at
Publication: |
280/775 |
International
Class: |
B62D 1/181 20060101
B62D001/181; B62D 1/187 20060101 B62D001/187 |
Foreign Application Data
Date |
Code |
Application Number |
May 25, 2012 |
JP |
2012-119918 |
May 28, 2012 |
JP |
2012-120384 |
Jun 26, 2012 |
JP |
2012-143029 |
Claims
1. An electric position adjustment apparatus for a steering wheel,
comprising: a steering shaft, with a steering wheel being supported
by and fastened to a rear-end section thereof; a column unit that
comprises: a support section that extends in an axial direction of
the steering shaft, supports the steering shaft on an inside
thereof so as to be able to freely rotate, is supported by a
portion that is fastened to a vehicle body or a vehicle body side
bracket that is supported by a portion that is fastened to the
vehicle body and does not displace during position adjustment of
the steering wheel; and an adjusted section that is supported by
the support section so as to be able to displace in the axial
direction of the steering shaft with at least part of the steering
shaft during position adjustment of the steering wheel; a moving
piece that comprises a concave engaging section, and is able to
displace in an axial direction of the column unit with an electric
motor as a driving source; and a transmission member that comprises
a base-end section that is connected to and fastened to the
adjusted section, and a tip-end section that engages with the
concave engaging section of the moving piece by way of a spacer,
and that is able to transmit movement of the moving piece to the
adjusted section, and the concave engaging section of the moving
piece having a cylindrical concave-shaped inner-circumferential
surface whose inner diameter does not change in an axial direction
of the transmission member; the tip-end section of the transmission
member having a cylindrical convex-shaped outer-circumferential
surface whose outer diameter does not change in the axial direction
of the transmission member; the spacer having a cylindrical
convex-shaped outer-circumferential surface whose outer diameter
does not change in the axial direction of the transmission member
and having a cylindrical concave-shaped inner-circumferential
surface whose inner diameter does not change in the axial direction
of the transmission member.
2. The electric position adjustment apparatus for a steering wheel
according to claim 1 further comprising a forward/backward feed
screw rod that, with displacement in the axial direction of the
column unit prevented, is located parallel with the column unit and
is able to rotate freely around a center axis of the
forward/backward feed screw rod by way of the electric motor;
wherein, the moving piece comprises a base section in which a screw
hole is formed that screws onto the screw rod, and a tip-end
section in which the concave engaging section is formed, and by
rotating the forward/backward feed screw rod in a desired
direction, the moving piece moves in an axial direction of the
forward/backward feed screw rod.
3. The electric position adjustment apparatus for a steering wheel
according to claim 1, wherein the transmission member further
comprises an outwardly protruding flange-shaped rim section in a
middle section in the axial direction of the transmission member;
an inner side spacer that is made of a hard material having an
outer diameter that is smaller than an outer diameter of the rim
section and that is located on a top surface of the rim section,
and an outer side spacer that is made of a material having a
vibration absorbing capability with a large internal loss and is
located around the inner side spacer, are arranged so that a bottom
surface of an inner diameter side portion of the outer side spacer
comes in contact with an outer diameter side portion of the top
surface of the rim section, and a ring spacer that is made of a
hard material and that has a wedge shaped cross-sectional shape is
held between top surfaces of the inner side spacer and the outer
side spacer and the outer circumferential surface of the adjusted
section.
4. The electric position adjustment apparatus for a steering wheel
according to claim 1, further comprising an intermediate shaft that
is linked with a front-end section of the steering shaft by way of
a universal joint such that torque can be transmitted; wherein the
steering shaft has integrated construction in which an entire
length thereof does not extend or contract; the adjusted section is
composed of a steering column having integrated construction in
which an entire length thereof does not extend or contract; the
intermediate shaft has construction in which an entire length
thereof can extend or contract; and by extending or contracting the
intermediate shaft, the whole steering shaft and the steering
column are able to displace.
5. The electric position adjustment apparatus for a steering wheel
according to claim 1 comprising a mechanism provided at at least
one location in an axial direction of the support section which is
located on an opposite side in a radial direction of the
transmission member, and the mechanism presses the adjusted section
in a direction toward the transmission member.
6. The electric position adjustment apparatus for a steering wheel
according to claim 1, wherein the adjusted section comprises: a
middle cylindrical section that is located in a middle section in
an axial direction of the adjusted section, and whose outer
diameter does not change in the axial direction of the adjusted
section; and reduced-diameter sections that are located on both end
sides in the axial direction of the middle cylindrical section and
whose outer diameters are smaller than an outer diameter of the
middle cylindrical section; the base-end section of the
transmission member is connected and fastened to the middle
cylindrical section, and mechanisms are provided at two locations
in the axial direction of the support section which is on the
opposite side in the radial direction of the transmission member,
which press the middle cylindrical section in the direction toward
the transmission member, with a space in the axial direction
between these mechanisms essentially being equal to the maximum
range of movement of the adjusted section in the axial direction of
the column unit.
Description
TECHNICAL FIELD
[0001] The present invention relates to an electric position
adjustment apparatus for a steering wheel, and more specifically to
an apparatus that is driven by an electric motor, and that adjusts
the forward/backward position and up/down position of a steering
wheel.
BACKGROUND ART
[0002] Various kinds of structure for electric position adjustment
apparatuses for a steering wheel are known, and some are already
being applied to steering apparatuses for automobiles. FIG. 21
illustrates a first example of conventional structure as disclosed
in JP 2010-116042 (A). A steering shaft 2 to which a steering wheel
1 is fastened has a cylindrical shaped outer shaft 3, and a
circular rod shaped inner shaft 4 that is inserted into the outer
shaft 3 and is able to slide in the axial direction and transmit
rotational force. More specifically, the inner circumferential
surface from the middle section to the front-end section of the
outer shaft 3 and the outer circumferential surface of the rear-end
section of the inner shaft 4 are connected with spline engagement.
The steering wheel 1 is fastened to the rear-end section of the
outer shaft 3.
[0003] The steering shaft 2 is inserted into a cylindrical steering
column 5, and is supported so as to be able to rotate freely. The
steering column 5 has a cylindrical shaped outer column 6 that is
supported by the vehicle body, and a cylindrical inner column 7
that is inserted into the outer column 6 so as to be able to slide
in the axial direction. The rear end side portion of the middle
section of the outer shaft 3 is supported on the inner side of the
rear-end section of the inner column 7 such that displacement in
the axial direction is prevented, and so as to be able to rotate
freely. Moreover, the front end side portion of the middle section
of the inner shaft 4 is supported on the inner side of the
front-end section of the outer column 6 such that displacement in
the axial direction is prevented, and so as to be able to rotate
freely. With this structure, the steering shaft 2 is supported on
the inside of the steering column 5 so as to be able to rotate
freely, and the outer shaft 3 and inner column 7 are able to move
in the forward/backward direction relative to the inner shaft 4 and
outer column 6.
[0004] The apparatus of this first example of conventional
structure is equipped with an electric actuator for making it
possible to adjust the forward/backward position of the steering
wheel 1 of a gear housing 8 that is fastened to the bottom surface
of the outer column 6; a feed nut 9 that is supported on the inside
of the gear housing 8 so that only rotation is possible with
displacement in the axial direction prevented; a push-pull arm 10
that is fastened to the portion on the rear-end section of the
inner column 7 that protrudes further toward the rear than the
outer column 6; a push-pull rod 11 having a male screw section 12
provided on the front half section thereof that screws into the
feed nut 9, and a rear-end section that is connected to the
push-pull arm 10; and an electric motor (not illustrated in the
figure) that is connected to the feed nut 9 by way of a worm
reduction gear 13, and that rotates and drives the feed nut 9.
[0005] When adjusting the forward/backward position of the steering
wheel 1, the feed nut 9 is rotated and the push-pull rod 11 is
caused to displace in the axial direction. As the push-pull rod 11
displaces, the inner column 7 displaces in the same direction as
the push-pull rod 11 by way of the push-pull arm 10, and by causing
the outer shaft 3 that is supported on the inside of the inner
column 7 to move in the forward/backward direction, the
forward/backward position of the steering wheel 1 is adjusted.
[0006] In the electric position adjustment apparatus for a steering
wheel of this first example of conventional construction, there is
a possibility that the driver that is operating the steering wheel
1 will have a strange or uncomfortable feeling due to a small gap
that exists in a joint section between the rear-end section of the
outer column 6 and the front-end section of the inner column 7. In
other words, in an electric position adjustment apparatus for a
steering wheel, differing from a manual apparatus, the diameter of
the rear-end section of the outer column 6 is not reduced even when
maintaining the position of the steering wheel 1 after adjustment,
so the small gap remains in the joint section. There is a
possibility that the inner column 7 that supports the outer shaft 3
to which the steering wheel 1 is fastened may move or vibrate with
respect to the outer column 6 that is supported by the vehicle
body. There is also a possibility, that due to this movement, the
support rigidity of the steering wheel 1 will decrease, giving the
driver that operates the steering wheel 1 an uncomfortable feeling.
Moreover, this backlash movement causes the resonant frequency of
the portion of the electric position adjustment apparatus for a
steering wheel that makes up the steering column apparatus that
includes the steering shaft 2 and steering column 5 to become
lower, and thus when there is minute vibration of the vehicle body
such as when traveling over a rough road, there is a possibility
that unpleasant noise or vibration will occur in this portion of
the steering column apparatus.
[0007] FIG. 22 and FIG. 23 illustrate a second example of
conventional structure as disclosed in JP 2006-297989 (A). In this
second example of conventional structure as well, using
construction similar to that of the first example of conventional
structure, a steering shaft 2a is supported inside a steering
column 5a so as to be able to rotate freely, and an outer shaft 3a
and inner column 7a move in the forward and backward direction
relative to an inner shaft 4a and outer column 6a.
[0008] In the apparatus of this second example of conventional
structure, by using a linear motion ultrasonic motor 15 that is
supported by the bottom end section of an installation bracket 14
as an electric actuator for making it possible to adjust the
forward/backward position of the steering wheel 1, it is possible
for the inner column 7a to displace in the axial direction with
respect to the outer column 6a. More specifically, a moving piece
16 of the linear motion ultrasonic motor 15 is connected with the
inner column 7a by a transmission member 17, and by transmitting
the movement of the moving piece 16 to the inner column 7a, the
inner column 7a is able to move in the forward/backward direction.
The base end section of the transmission member 17 is linked with
the moving piece 16 by way of a spherical joint 18. The spherical
joint 18 has: a concave engaging section 19 that is formed in the
moving piece 16; a spacer 20 that fits with and is supported by the
concave engaging section 19, and that has an inner circumferential
surface that is a spherical concave surface; a spherical engaging
section 21 that is provided on the tip-end section of the
transmission member 17, and has an outer circumferential surface
that is a spherical convex surface that fits spherically with the
inner circumferential surface of the spacer 20.
[0009] When adjusting the forward/backward position of the steering
wheel 1, the linear motion ultrasonic motor 15 causes the moving
piece 16 to displace in the axial direction of the steering column
5a. This displacement, by way of the transmission member 17, causes
the inner column 7a to displace in the same direction as the moving
piece 16, which causes the outer shaft 3a that is supported on the
inside of the inner column 7a to displace in the forward/backward
direction together with the inner column 7a. As a result, as
illustrated by the two-dot chain line, it becomes possible to
adjust the forward/backward position of the steering wheel 1.
[0010] In the case of this second example of conventional
structure, there is a structural problem in that the manufacturing
cost for maintaining smooth operation of the engaging section
between the moving piece 16 and the transmission member 17
increases. In other words, in order to smoothly perform adjustment
of the forward/backward position of the steering wheel 1 without
backlash movement, it is necessary to adequately regulate the
engagement strength of the engaging section between the spherical
engaging section 21 of the transmission member 17 and the engaging
section of the spacer 20. When this engagement strength is too low,
there is a positive gap in the engaging section, so backlash
movement occurs between the spherical engaging section 21 and
spacer 20, and thus it becomes easy for backlash movement of the
steering wheel 1 to occur in the forward/backward direction. On the
other hand, when this engagement strength is too high, it becomes
impossible for pivotal displacement of the spacer 20 with respect
to the spherical engaging section 21 to be performed smoothly.
[0011] In this second example of conventional structure, the amount
of movement of the moving piece 16 in the forward/backward
direction is large, and unless there is a good degree of
parallelism between the direction of movement of this moving piece
16 and the direction of movement of the inner column 7a during
adjustment of the forward/backward position of the steering wheel
1, the transmission member 17 will displace in the axial direction
of this transmission member 17 relative to the moving piece 16 due
to the adjustment of the forward/backward position of the steering
wheel 1. This relative movement causes rubbing in the axial
direction of the transmission member 17 between the outer
circumferential surface of the spacer 20 and the inner
circumferential surface of the concave engaging section 19. When
this occurs and the engagement strength is too high and pivotal
displacement of the spacer 20 with respect to the spherical
engaging section 21 is not performed smoothly, there will be strong
rubbing between the outer circumferential surface of the spacer 20
and the inner circumferential surface of the concave engaging
section 19, and there will be a possibility that strange noise or
vibration will occur, causing the passengers to have an
uncomfortable feeling. Particularly, in this state, the surface
that allows relative displacement in the axial direction of the
transmission member 17 between the transmission member 17 and the
moving piece 16 is limited to one location on the outer
circumferential surface of the spacer 20 and the inner
circumferential surface of the concave engaging section 19, so it
becomes easy for the rubbing length to become long, and thus it
becomes even easier for strange noise or vibration to occur.
[0012] Highly precise processing of the inner circumferential
surface of the spacer 20, which is a concave spherical surface, and
the outer circumferential surface of the spherical engaging section
21, which is a convex spherical surface, in order to prevent the
occurrence of this strange noise or vibration leads to a high cost.
Moreover, even when the spherical engaging section 21 is accurately
manufactured, it is impossible to avoid the outer diameter of the
transmission member 17 from becoming small at the base end section
of the spherical engaging section 21. Therefore it becomes easy for
large stresses to occur in the neck section of the transmission
member 17 during adjustment of forward/backward position of the
steering wheel 1, and thus this kind of construction is
disadvantageous from the aspect of maintaining sufficient
durability during use over a long period of time.
[0013] As a structure for preventing the occurrence of strange
noise or vibration in portions of the steering column apparatus,
there is a mechanism such as illustrated in FIG. 24 and disclosed
in JP 5,076,908 (B2) in which retaining holes 22 are formed in part
in the axial direction of an outer column 6b, and by adjustment
screws 24 that are screwed into female screws 23 that are formed in
the retaining holes 22 pressing synthetic resin pads 26 so as to be
in contact with the outer circumferential surface of an inner
column 7b, backlash movement of portions of the steering column
apparatus is prevented. However, in this mechanism, when the
pressure force for pressing the pads 26 against the outer
circumferential surface of the inner column 7b is made just large
enough so that backlash movement can be prevented, the friction
force when moving the outer column 6b and inner column 7b becomes
large, so there is a problem in that the drive load on the motor,
such as an electric motor, becomes large and the operating sound
becomes large.
RELATED LITERATURE
Patent Literature
[0014] [Patent Literature 1] JP 2010-16042 (A) [0015] [Patent
Literature 2] JP 2006-297989 (A) [0016] [Patent Literature 3] JP
5,076,908 (B2) [0017] [Patent Literature 4] JP H09-323658 (A)
[0018] [Patent Literature 5] JP H10-119793 (A) [0019] [Patent
Literature 6] JP 2005-255040 (A) [0020] [Patent Literature 7] JP
2009-006743 (A) [0021] [Patent Literature 8] JP 2010-116042 (A)
[0022] [Patent Literature 9] DE 10251764 (A1)
SUMMARY THE INVENTION
Problem to be Solved by the Invention
[0023] The object of the present invention is to provide at low
cost construction of an electric position adjustment apparatus for
a steering wheel that improves the rigidity of portions of a
steering column apparatus, and enables stable and smooth operation
of position adjustment for a steering wheel without causing the
driver that operates the steering wheel to have a strange
feeling.
Means for Solving the Problems
[0024] The electric position adjustment apparatus for a steering
wheel of the present invention has:
[0025] a steering shaft, with a steering wheel being supported by
and fastened to a rear-end section thereof;
[0026] a column unit that has: a support section that extends in an
axial direction of the steering shaft, supports the steering shaft
on an inside thereof so as to be able to freely rotate, is
supported by a portion that is fastened to a vehicle body or a
vehicle body side bracket that is supported by a portion that is
fastened to the vehicle body and does not displace during position
adjustment of the steering wheel; and an adjusted section that is
supported by the support section so as to be able to displace in
the axial direction of the steering shaft with at least part of the
steering shaft during position adjustment of the steering
wheel;
[0027] a moving piece that has a concave engaging section, and with
an electric motor as a driving source, is able to displace in an
axial direction of the column unit; and
[0028] a transmission member that has a base-end section that is
connected to and fastened to the adjusted section, and a tip-end
section that engages with the concave engaging section of the
moving piece by way of a spacer, and that is able to transmit
movement of the moving piece to the adjusted section.
[0029] Particularly, a feature of the electric position adjustment
apparatus for a steering wheel of the present invention is that the
concave engaging section of the moving piece has a cylindrical
concave-shaped inner-circumferential surface whose inner diameter
does not change in an axial direction of the transmission member;
the tip-end section of the transmission member has a cylindrical
convex-shaped outer-circumferential surface whose outer diameter
does not change in the axial direction of the transmission member;
the spacer has a cylindrical convex-shaped outer-circumferential
surface whose outer diameter does not change in the axial direction
of the transmission member and has a cylindrical concave-shaped
inner-circumferential surface whose inner diameter does not change
in the axial direction of the transmission member.
[0030] In the electric position adjustment apparatus for a steering
wheel of the present invention, the mechanism for causing the
moving piece to displace is not limited to an electric motor,
however, in one aspect of the present invention, the electric
position adjustment apparatus for a steering wheel comprises a
forward/backward feed screw rod that, with displacement in the
axial direction of the column unit prevented, is located parallel
with the column unit and is able to rotate freely around a center
axis of the forward/backward feed screw rod by way of the electric
motor; wherein, the moving piece has a base section in which a
screw hole is formed that screws onto the screw rod, and a tip-end
section in which the concave engaging section is formed, and by
rotating the forward/backward feed screw rod in a desired
direction, the moving piece moves in an axial direction of the
forward/backward feed screw rod.
[0031] Moreover, in one aspect of the present invention, the
transmission member further has an outwardly protruding
flange-shaped rim section provided in a middle section in the axial
direction of the transmission member; an inner side spacer that is
made of a hard material having an outer diameter that is smaller
than an outer diameter of the rim section and that is located on a
top surface of the rim section, and an outer side spacer that is
made of a material having a vibration absorbing capability with a
large internal loss and is located around the inner side spacer,
are arranged so that a bottom surface of an inner side portion of
the outer side spacer comes in contact with an outer diameter side
portion of the top surface of the rim section, and a ring spacer
that is made of a hard material and that has a wedge shaped
cross-sectional shape is held between top surfaces of the inner
side spacer and the outer side spacer and the outer circumferential
surface of the adjusted section.
[0032] In one aspect of the present invention, the electric
position adjustment apparatus for a steering wheel further has an
intermediate shaft that is linked with a front-end section of the
steering shaft by way of a universal joint such that torque can be
transmitted; wherein the steering shaft has integrated construction
in which an entire length thereof does not extend or contract; the
adjusted section is composed of a steering column having integrated
construction in which an entire length thereof does not extend or
contract; the intermediate shaft has construction in which an
entire length thereof can extend or contract; and by extending or
contracting the intermediate shaft, the whole steering shaft and
the steering column are able to displace.
[0033] However, the present invention is not limited to this
aspect, and, for example, the present invention can also be applied
to construction in which the steering shaft is composed of an outer
shaft, and an inner shaft that corresponds to part of the steering
shaft and that is inserted into the outer shaft so as to be able to
slide in the axial direction of the steering shaft, and so as to be
able to transmit rotational force; the column unit is such that the
support section is composed of an outer column, and the adjusted
section is composed of an inner column that is inserted into the
outer column so as to be able to slide in the axial direction of
the column unit; and when adjusting the position of the steering
wheel, the inner column and the outer shaft are displaced in the
axial direction of the steering shaft with respect to the outer
column and the inner shaft.
[0034] In one aspect of the present invention, preferably a
mechanism is provided at at least one location, and preferably at
least two locations, in an axial direction of the support section
which is located on an opposite side in a radial direction of the
transmission member, and presses the adjusted section in a
direction toward the transmission member.
[0035] Moreover, the adjusted section is preferably composed of a
middle cylindrical section that is located in a middle section in
an axial direction of the adjusted section and whose outer diameter
does not change in the axial direction of the adjusted section, and
reduced-diameter sections that are located on both end sides in the
axial direction of the middle cylindrical section and whose outer
diameters are smaller than an outer diameter of the middle
cylindrical section.
[0036] In this case, preferably, the base-end section of the
transmission member is connected and fastened to the middle
cylindrical section, and mechanisms are provided at two locations
in the axial direction of the support section which is located on
the opposite side in the radial direction of the transmission
member, which press the middle cylindrical section in the direction
toward the transmission member. These mechanisms are provided such
that, regardless of displacement in the axial direction of the
adjusted section with respect to the support section, the
mechanisms do not separate from the middle cylindrical section.
[0037] In the case where mechanisms that press the adjusted section
toward the transmission member are provided at two locations in the
axial direction of the support section, it is further preferred
that the space in the axial direction between these mechanisms be
essentially equal to the maximum range of movement of the adjusted
section in the axial direction of the column unit.
[0038] Preferably, a pair of pre-loaded angular ball bearings
having back-to-back contact angles are placed between the inner
circumferential surface of the reduced-diameter section of the
adjusted section and the outer circumferential surface of at least
part of the steering shaft, and the steering shaft is supported by
the adjusted section so as to be able to rotate freely, and so that
displacement in the axial direction with respect to the adjusted
section is prevented.
[0039] It is possible to employ construction in which each
mechanism that presses the adjusted section downward has a
retaining hole that is formed so as to connect the inner
circumferential surface and outer circumferential surface of the
support section, with a sliding plate, an elastic member and a
cover being assembled in the retaining hole in order from the
inside in the radial direction of the support section, where the
elastic member is elastically compressed between the sliding plate
and the cover, and the sliding plate presses the outer
circumferential surface of the adjusted section.
Effect of the Invention
[0040] With the present invention, an electric position adjustment
apparatus for a steering wheel that is able to stably and smoothly
perform the operation of adjusting the position of the steering
wheel is achieved at low cost.
[0041] First, cost reduction is achieved by simplifying the shape
of a transmission member and spacer that transmit movement of a
moving piece to an adjusted section of a column unit. In other
words, the shapes of the portions where the transmission member and
the spacer engage are simple cylindrical surfaces, so these members
can be manufactured with high precision and at low cost by cold
plastic working such as cold forging.
[0042] Moreover, relative displacement of the transmission member
and moving piece in the axial direction of the transmission member
is compensated for in at two locations; between the inner
circumferential surface of the spacer and the outer circumferential
surface of the tip-end section of the transmission member, and the
outer circumferential surface of the spacer and the inner
circumferential surface of the concave engaging section that is
provided in the moving piece. In other words, when the direction of
movement of the moving piece and the direction of movement of the
adjusted section of the column unit due to forward/backward
position adjustment of the steering wheel are non-parallel due to
these members rubbing at two locations, and when there is relative
displacement in the axial direction of the transmission member of
the transmission member and moving piece due to this
forward/backward position adjustment, the length of rubbing in
these rubbing areas can be shortened, so the occurrence of strange
noise and vibration is suppressed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0043] FIG. 1 is a vertical section side view illustrating a first
example of an embodiment of the present invention.
[0044] FIG. 2 is an enlarged view of the right half of FIG. 1.
[0045] FIG. 3 is an enlarged view of area A in FIG. 2.
[0046] FIG. 4 is an enlarged view of area B in FIG. 2.
[0047] FIG. 5 is an enlarged view of area C in FIG. 2.
[0048] FIG. 6 is a perspective view of the first example, and
illustrates the state as seen from above.
[0049] FIG. 7 is an enlarged view of the right half of FIG. 6.
[0050] FIG. 8 is a perspective view illustrating the state of the
opposite side of FIG. 7 as seen from above.
[0051] FIG. 9 is a perspective view illustrating the state of the
right half of FIG. 6 as seen from underneath.
[0052] FIG. 10 is a partial cross-sectional view of the end surface
of the state as seen from the right in FIG. 1 and FIG. 2.
[0053] FIG. 11 is a partial cross-sectional view illustrating the
state as seen from the left in FIG. 1.
[0054] FIG. 12 is a top view illustrating the state as seen from
above in FIG. 2.
[0055] FIG. 13 is a bottom view illustrating the state as seen from
underneath in FIG. 2.
[0056] FIG. 14 is an enlarged cross-sectional view of section D-D
in FIG. 2.
[0057] FIG. 15 is an enlarged cross-sectional view of section E-E
in FIG. 2.
[0058] FIG. 16 is a partial enlarged cross-sectional view of the
support sections on both the front and rear ends of a screw rod for
adjusting the forward/backward position in the first example, and
illustrates the state as seen from the same direction in FIG. 1 and
FIG. 2.
[0059] FIG. 17 is a partial enlarged cross-sectional view of the
support sections on both the top and bottom ends of a screw rod for
adjusting the up/down position in the first example, and
illustrates the state as seen from the same direction in FIG. 1 and
FIG. 2.
[0060] FIG. 18 is a schematic drawing for explaining the state in
the first example when the amount of extension or contraction of an
intermediate shaft changes according to the forward/backward
position of the steering wheel as the adjustment of the up/down
position of the steering wheel is adjusted.
[0061] FIG. 19 is a vertical section side view illustrating a
second example of an embodiment of the present invention.
[0062] FIG. 20 is an enlarged view of area F in FIG. 19.
[0063] FIG. 21 is a partial vertical section side view illustrating
a first example of conventional structure.
[0064] FIG. 22 is a vertical section side view illustrating a
second example of conventional structure.
[0065] FIG. 23 is an enlarged view of area G in FIG. 22.
[0066] FIG. 24 is a partial cross-sectional view illustrating a
conventional gap adjustment mechanism for adjusting a gap between
an outer column and an inner column that can be applied to the
first and second example of conventional structure.
MODES FOR CARRYING OUT THE INVENTION
First Example
[0067] FIG. 1 to FIG. 18 illustrate a first example of an
embodiment of the present invention. The electric position
adjustment apparatus for a steering wheel has a steering shaft 2b
and a cylindrical steering column 5b, neither of which is
extendable or contractible, in the portion that makes up a steering
column apparatus. In the construction of this example, the
forward/backward position and the up/down position of a steering
wheel 1 that is supported by and fastened to the rear-end section
of the steering shaft 2b that protrudes from an opening on the rear
end of the steering column 5b (see FIG. 21) can be adjusted within
specified ranges, wherein, adjustment of the forward/backward
position of the steering wheel 1 is achieved by moving the entire
steering shaft 2b and steering column 5b in the axial direction.
Therefore, in this example, the entire steering column 5b
corresponds to an adjusted section of a column unit of the present
invention.
[0068] In the construction of this example, in order for the
steering shaft 2b to be able to move in the axial direction
(forward/backward direction) without the overall length thereof
extending or contracting, construction is applied that makes it
possible to transmit torque and makes it possible for the entire
length to extend and contract by using an intermediate shaft 28,
which is formed by joining an intermediate inner shaft 29 and an
intermediate outer shaft 30 together using a spline engagement,
that is connected to the front-end section of the steering shaft 2b
so as to be able to transmit torque by way of a universal joint 27a
as illustrated in FIG. 1 to FIG. 6. In other words, the movement in
the forward/backward direction of the steering shaft 2b is
compensated for by the extension or contraction of the intermediate
shaft 28. The front-end section of the intermediate shaft 28 is
linked to the input shaft (not illustrated in the figure) of a
steering gear unit for applying a steering angle to the steered
wheels (front wheels) by way of another universal joint 27b.
[0069] Moreover, in the construction of this example, in order that
position adjustment of the steering wheel 1 can be performed
smoothly, the installation location of the universal joint 27a that
links the front-end section of the steering shaft 2b and the
rear-end section of the intermediate shaft 28 is appropriately
regulated, and the amount of relative displacement between the
steering shaft 2b and the intermediate shaft 28 during position
adjustment of the steering wheel 1 is kept small. More
specifically, in order to support a column holder 31 that holds the
steering column 5b so as to be able to pivotally displace with
respect to a vehicle body side bracket 32, a pair of left and right
tilt shafts 33 that are concentric with each other (see FIG. 9 and
FIG. 11) and the steering shaft 2b are arranged at positions where
the respective center lines of each cross each other. Furthermore,
as illustrated in FIG. 3, the center line O.sub.C of the pair of
tilt shafts 33 is located in the middle position in the
forward/backward direction between the center position O.sub.F of
displacement on the front-end side and the center position of
displacement O.sub.B of displacement on the rear-end side of the
universal joint 27a.
[0070] The center position O.sub.F of displacement on the front
side is the center position of displacement of the universal joint
27a in the state where the steering wheel 1 has been displaced to
the front-end position of the adjustable range, or in other words,
is the center point position of the joint spider 34 of the
universal joint 27a in this state. Moreover, the center position
O.sub.B of displacement on the rear-end side is the center position
of displacement of the universal joint 27a in a state where the
steering wheel 1 has been displaced to the rear-end position of the
adjustable range. In this example, the center line O.sub.C of the
pair of tilt shafts 33 is located in the middle position of a
connecting line segment that connects the center position O.sub.F
of displacement on the front-end side and the center position
O.sub.B of displacement on the rear-end side. Therefore, when the
length of the connecting line segment that connects the center
position O.sub.F of displacement on the front-end side and the
center position O.sub.B of displacement on the rear-end side is
taken to be L, the distances from the center line O.sub.C of the
pair of tilt shafts 33 to the center position O.sub.F of
displacement on the front-end side and the center position O.sub.B
of displacement on the rear-end side are both L/2. Even when the
center line O.sub.C of the pair of tilt shafts 33 shifts forward or
backward .+-.L/10 or more preferably .+-.L/20 from the position
illustrated in the figure, the center line O.sub.C of the pair of
tilt shafts 33 is still located in nearly the middle position in
the forward/backward direction between the center position O.sub.F
of displacement on the front-end side and the center position
O.sub.B of displacement on the rear-end side, so no particular
trouble occurs.
[0071] The column holder 31 that holds the steering column 5b such
that displacement in the axial direction (forward/backward
direction) is possible is formed into a cylindrical shape, and more
specifically, is formed into a circular cylindrical shape by die
casting of a light alloy, for example. The column holder 31
corresponds to the support section of the column unit of the
present invention. In order to eliminate the backlash movement of
the steering column 5b with respect to the column holder 31,
retaining holes 22a are formed at two locations on the top surface
of the column holder 31 that are separated in the forward/backward
direction, and are formed so as to connect the inner
circumferential surface and outer circumferential surface of the
column holder 31. As illustrated in FIG. 4 and FIG. 14, a sliding
plate 35, a washer 36, a disc spring 37 are located on the inside
of each retaining hole 22a, and the opening on the top end of the
retaining hole 22a is covered by a screw cap 38. The sliding plate
35 is made of a high polymer material having excellent sliding
properties such as synthetic resin like polyacetal (POM), synthetic
rubber or the like. In this state, the sliding plates 35 that are
located in the end sections on the inner side of the retaining
holes 22a are pressed by the elastic force of the disc springs 37
against the outer circumferential surface (top surface) of the
steering column 5b so that there is no backlash movement of the
steering column 5b on the inside of the column holder 31. The
spacing in the axial direction between these mechanisms for
preventing backlash movement of the steering column 5b is
arbitrary, however, in this example, the spacing in the axial
direction is practically equal to the maximum movable range in the
axial direction of the steering unit.
[0072] In this example, from the aspect of maintaining the
necessary rigidity, the steering column 5b is integrally formed
into a cylindrical shape using extruded tube or
electro-resistance-welded tube made of aluminum alloy, iron alloy,
and the like. However, it is also possible to use combined
construction in which plural elements are welded or joined
together. In this example, the steering column 6b has a
substantially cylindrical shape; however, the shape is not limited
to this. By performing a drawing process on both end sections in
the forward/backward direction of the steering column 5b,
reduced-diameter sections 39a, 39b having an outer diameter that is
less than the outer diameter of the middle section in the
forward/backward direction are formed. Moreover, the middle section
in the forward/backward direction of the steering column 5b is a
middle cylindrical section 40 whose outer diameter does not change
in the axial direction, and both end sections in the
forward/backward direction of the middle cylindrical section 40 are
connected to the reduced-diameter sections 39a, 39b by inclined
surface sections 41a, 41b. The length in the axial direction of the
middle cylindrical section 40 and the installation positions of the
retaining holes 22a are regulated by the relationship with the
amount of adjustment in the forward/backward direction of the
steering wheel 1, and is such that the sliding plates 35 are not
separated from the middle cylindrical section 40 regardless of the
position in the axial direction of the steering column 5b with
respect to the column holder 31.
[0073] The steering shaft 2b is integrally formed into a
cylindrical shape or circular rod shape using extruded tube or
electro-resistance-welded tube made of an iron alloy, or using
extruded tube or drawn pipe that is made of aluminum alloy,
however, as in the case of the steering column 5b, it is also
possible to use combined construction of plural elements that are
welded or joined. The steering shaft 2b is supported by a pair of
ball bearings 42a, 42b that are arranged at both end sections in
the forward/backward direction such that displacement in the axial
direction with respect to the steering column 5b is prevented, and
so as to be able to rotate freely.
[0074] The pair of ball bearings 42a, 42b are both angular ball
bearings having back-to-back contact angles, and in a preloaded
state, are located between the inner circumferential surface of the
reduced-diameter sections 39a, 39b and the outer circumferential
surface of the portions near both ends of the middle section of the
steering shaft 2b. Therefore, in this example, as illustrated in
FIG. 4, the outer rings 43a, 43b of the pair of ball bearings 42a,
42b are fixed into the opening edge sections of the
reduced-diameter sections 39a, 39b, and are prevented from
displacement in a direction toward each other. Moreover, the inner
ring 44a of the ball bearing 42a on the front side is fastened onto
the front end side portion of the middle section of the steering
shaft 2b by a retaining ring 45 that is fixed to the steering shaft
2b such that displacement in the forward direction is prevented. On
the other hand, the inner ring 44b of the ball bearing 42b on the
rear side is fastened onto the steering shaft 2b with a loose fit
using a push nut 46 such that displacement in the backward
direction is prevented. An elastic material 47 such as a disc
spring is held between the surface on the front side of the push
nut 46 and the surface on the rear end of the inner ring 44b, and
this elastic material 47 applies an elastic force in the forward
direction to the inner ring 44b. With the construction described
above, the steering shaft 2b is supported on the inner side of the
steering column 5b such that displacement in the axial direction is
prevented, there is no backlash movement, and so as to be able to
rotate freely.
[0075] In this example, instead of deep-groove ball bearings,
back-to-back combined angular ball bearings are used as the pair of
ball bearings 42a, 42b, and are arranged so as to be preloaded in
the axial direction of the steering shaft 2b. Therefore, by
preloading, it is possible to prevent backlash in the bearings, and
it is possible to reduce the rotary torque of the bearings, so a
steering apparatus having good steering stability of the steering
wheel 1 is achieved. Moreover, a push nut 46 is used for fastening
the inner ring 44 on the rear side, so it is not necessary to form
a retaining groove on the rear-end section of the steering shaft 2b
to which large stress from the steering wheel 1 can be easily
applied. Therefore, it is possible to maintain the strength and
rigidity of the rear-end section of the steering shaft 2b without
increasing the thickness of the steering shaft 2b. Furthermore, a
screw hole 48 is provided on the rear-end section of the steering
shaft 2b, and by supporting and fastening the steering wheel 1
using this screw hole 48, the diameter of the rear-end section of
the steering shaft 2b is sufficiently maintained.
[0076] As illustrated in FIG. 9 and FIG. 11, the column holder 31
is supported with respect to a vehicle body side bracket 32 by a
pair of tilt shafts 33 that are provided on both sides of the
front-end section of the column holder 31 so as to be concentric
with each other, and so that the column holder 31 is able to
pivotally displace around these tilt shafts 33 as a center. The
vehicle body side bracket 32 is integrally formed by die casting of
a light alloy, for example, and is supported by a portion that is
fastened to the vehicle body so as to be able to displace in the
forward direction due to an impact load that is applied during a
secondary collision. To accomplish this, a pair of left and right
installation plate sections 49 are provided on the vehicle body
side bracket 32; a long hole 50 that extends in the
forward/backward direction is formed in the front section of each
of these installation plate sections 49; and a notch 51 that is
open on the rear-end edge of the installation plate section 49 is
formed on the rear-end sections. Sliding plates 52a, 52b are fixed
in the long holes 50 and notches 51, and the pair of installation
plate sections 49 are supported by a portion that is fastened to
the vehicle body by bolts or studs that are inserted into through
holes in these sliding plates 52a, 52b. In this state, the vehicle
body side bracket 32 is normally securely fastened, however, when a
large impact load is applied in the forward direction during a
secondary collision, the bolts or studs displace within a
displaceable range inside the long holes 50.
[0077] An actuator casing 53 that is formed separate from the
steering column 5b is joined and fastened to the portion of the
column holder 31 on the bottom side of the steering column 5b by
plural bolts. As illustrated in FIG. 2 and FIG. 5, a
forward/backward direction feed screw apparatus 54 and an up/down
feed screw apparatus 55 of an electric actuator are provided inside
the actuator casing 53. In this example, an electric actuator for
forward/backward position adjustment is composed of the
forward/backward direction feed screw apparatus 54 and a
forward/backward electric drive motor 56. The forward/backward
direction feed screw apparatus 54 has the forward/backward electric
drive motor 56 as a drive source, and is for causing the steering
column 5b, to displace in the forward/backward direction, and
includes a forward/backward feed screw rod 58 that is arranged
parallel with the steering column 5b, and a moving piece 16a that
is composed of a forward/backward feed nut that is screwed onto the
forward/backward feed screw rod 58. As illustrated in FIG. 5 and
FIG. 16, both the front and rear end sections of the
forward/backward feed screw rod 58 are supported by the actuator
casing 53 by way of a pair of ball bearings 59a, 59b such that
displacement in the axial direction is prevented and so as to only
be able to rotate. The forward/backward feed screw rod 58 is
connected to the forward/backward electric drive motor 56 by way of
a worm reduction gear, and is rotated and driven by the
forward/backward electric drive motor 56. In this example, the
forward/backward feed screw apparatus 54 having the
forward/backward electric drive motor 56 as a drive source is used;
however, it is also possible to use a linear motor, such as a
linear motion ultrasonic motor that has a brake function.
[0078] The moving piece (forward/backward feed nut) 16a has a base
section 60 and a connecting section 61 that is provided in the
upper part thereof. A screw hole 62 that screws onto the
forward/backward feed screw rod 58 is formed in the base section
60. The connecting section 61 and the steering column 5b are
connected by a transmission member 17a such that force can be
transmitted in the forward/backward direction. The transmission
member 17a is formed by performing cold forging of a material made
of an iron-based alloy such as carbon steel or stainless steel, and
a male screw section 63 is provided on the base-end section
(top-end section), an outwardly protruding flange-shaped rim
section 64 is provided in the middle section, and a circular column
section 65 is provided on the tip-end section (bottom-end section).
An engaging hole 66, such as a hexagonal hole, is formed in the
surface of the tip end (bottom-end surface) of the circular column
section 65 so that the tip-end section of a tool such as a
hexagonal wrench can be engaged. There is no neck section in the
transmission member 17a of this example where the outer diameter
becomes particularly small.
[0079] As illustrated in FIG. 5 and FIG. 14, the transmission
member 17a is fastened by screws to the bottom surface of the
middle cylindrical section 40 of the steering column 5b so that
tilting in the forward/backward direction is sufficiently
suppressed. More specifically, a nut plate 68 is mounted to the
steering column 5b from the inner circumferential surface side of
the nut plate 68 by being crimped and fastened to the
circumferential edge section of a through hole 67 that is formed in
the bottom surface of the middle cylindrical section 40 of the
steering column 5b, with a cylindrical section thereof being
inserted into the through hole 67. An inner side spacer 69 having
an outer diameter that is smaller than the outer diameter of the
rim section 64 is placed on the top surface of the rim section 64,
and an outer side spacer 70 is mounted around the outside of this
inner side spacer 69. The inner side spacer 69 is made of a hard
material such as an iron-based alloy. On the other hand, the outer
side spacer 70 is made of a high polymer such as synthetic resin,
hard rubber, hard vinyl or the like, or is made of a material such
as soft metal that has a specified hardness, but also has a
vibration absorption capability with a large internal loss. The
inner side bottom surface of the outer side spacer 70 comes in
contact with the outer diameter side top surface of the rim section
64, with the top surface of the inner side spacer 69 and the top
surface of the outer side spacer 70 being located on the same
plane. Furthermore, a ring spacer 71 is held between the top
surfaces of the inner side spacer 69 and outer side spacer 70 and
the bottom surface (outer circumferential surface of the bottom-end
section) of the steering column 5b. The ring spacer 71 is made of a
hard material such as an iron-based alloy, and has a wedge shaped
cross-sectional shape; and the entire body of the ring spacer 71 is
formed into a circular ring shape or a frame shape. The male screw
section 63 that is provided on the top-end section of the
transmission member 17a screws into the nut plate 68, and by
further tightening, the transmission member 17a is securely
supported by and fastened to the bottom surface of the middle
section of the steering column 5. The transmission member 17a is
supported by and fastened to the middle cylindrical section 40 of
the steering column 5b that has a relatively large outer diameter,
so does not obstruct the rotation of the steering shaft 2b.
Moreover, by combining the transmission member 17a with the inner
side spacer 69 that is made of a hard material, the outer side
spacer 70 hardly becomes worn even after being used over a long
period of time. Furthermore, even in the case in which the outer
side spacer 70 drops downward from the rim section 64 and comes in
contact with the moving piece 16a, the occurrence of strange noise
due to the material thereof is suppressed.
[0080] The transmission member 17a that is supported by and
fastened to the bottom surface of the middle cylindrical section 40
of the steering column 5b and the moving piece 16a that is screwed
into the forward/backward feed screw rod 58 are combined so as to
be able to transmit movement in the forward/backward direction, and
to be capable of relative displacement in the axial direction of
the transmission member 17a. More specifically, a concave engaging
section 19a that is open on the top is provided in the center
section of the connecting section 61 of the moving piece 16a, and
the circular column section 65 of the transmission member 17a is
inserted inside this concave engaging section 19a. A cylindrical
shaped spacer 72 is located between the inner circumferential
surface of the concave engaging section 19a and the outer
circumferential surface of the circular column section 65 such that
there is no backlash movement, and so that sliding in the axial
direction of the circular column section 65 is possible. The inner
circumferential surface and outer circumferential surface of the
cylindrical shaped spacer 72 are such that, except for chamfered
sections on both end sections in the axial direction, are
cylindrical surfaces whose diameters do not change going in the
axial direction.
[0081] With the transmission member 17a and the moving piece 16a
combined, the moving piece 16a is not able to rotate with respect
to the forward/backward feed screw rod 58. As the forward/backward
electric drive motor 56 rotates the forward/backward feed screw rod
58, the moving piece 16a moves along the forward/backward feed
screw rod 58 in a direction corresponding to the rotation
direction. The direction of movement of the moving piece 16a is
basically parallel with the direction of movement of the steering
column 5b, which is the direction of the center axis of the column
holder 31. However, due to error in manufacturing or assembly of
the product, the direction of movement of the moving piece 16a and
the direction of movement of the steering column 5b may be a little
nonparallel. For example, when the direction of the engaged section
(bonded surface) of the bottom surface of the column holder 31 and
the top surface of the actuator casing 53 does not match the
direction of movement on the moving piece 16a or the direction of
movement of the steering column 5b, these directions of movement
may become a little nonparallel with each other. In this case, the
transmission member 17a displaces in the axial direction of the
transmission member 17a relative to the moving piece 16a. This
relative displacement is performed while sliding over the area of
contact between the inner circumferential surface of the
cylindrical spacer 72 and the outer circumferential surface of the
circular column section 65, and the area of contact between the
outer circumferential surface of the cylindrical spacer 72 and the
inner circumferential surface of the concave engaging section 19a.
The circumferential surfaces are simple cylindrical surfaces, so
highly precise processing without increased costs is possible, and
there are sliding areas at two locations between these members, so
relative displacement between these members is performed smoothly.
In order that the transmission member 17a is able to displace in
the forward/backward direction, a long hole 89 that extends in the
forward/backward direction is provided in part of the column holder
31, the long hole 89 extending in the axial direction of the column
holder 31.
[0082] In this example, there is a up/down feed screw apparatus 55
and an up/down electric drive motor 57 that function as an electric
actuator for adjusting the position in the up/down direction. The
up/down feed screw apparatus 55, with the up/down electric drive
motor 57 as a drive source, causes the rear section of the steering
column 5b to displace (go up or down) in the up/down direction. In
this example, the up/down feed screw apparatus 55 is constructed so
as to cause the entire column holder 31 to pivotally displace
around a pair of tilt shafts 33 with respect to the vehicle body
side bracket 32. More specifically, as illustrated in FIG. 8 and
FIG. 10, a U-shaped holding frame 73 is provided on the rear-end
section of the vehicle body side bracket 32, and the rear-end
section of the column holder 31 is held inside this holding frame
73 so as to be able to move up and down, and such that there is no
backlash movement. The holding frame 73 has inside surfaces that
are parallel with each other. On the other hand, convex sections
74a, 74b having outside surfaces that are parallel to each other
are provided on the both the left and right sides of the rear-end
section of the column holder 31, and protrude outward in the width
direction. The outside surfaces of the convex sections 74a, 74b and
the inside surfaces of the holding frame 73 fit together by way of
sliding plates 75a, 75b. One sliding plate 75a of the sliding
plates 75a, 75b is thicker than the other sliding plate 75b. By
pressing this thick sliding plate 75a toward the other sliding
plate 75b by a pressure screw 76, backlash movement between the
holding frame 73 and the column holder 31 is eliminated. The
pressure screw 76, after being tightened to a specified torque, can
be prevented from becoming loose by a lock nut. In this example,
the up/down feed screw apparatus 55 having the up/down electric
drive motor 57 is used, however, alternatively, it is also possible
to use a linear motor such as a linear motion ultrasonic motor that
has a brake function.
[0083] As a result of the combination of the engaging hole 77 that
is provided in the center section in the width direction of the
bottom-end section of the holding frame 73 and the up/down feed
screw apparatus 55, the rear-end section of the column holder 31,
as illustrated in FIG. 5 and FIG. 15, is able to move up and down
(raise and lower) based on the current flowing to the up/down
electric drive motor 57. As illustrated in FIG. 5 and FIG. 17, both
the top and bottom end sections of an up/down feed screw rod 78 of
the up/down feed screw apparatus 55 are supported by the actuator
casing 53 by way of a pair of ball bearing 79a, 79b so that only
rotation is possible. The up/down feed screw rod 78 is connected to
the up/down electric drive motor 57 by way of a worm reduction
gear, and is rotated and driven by the up/down electric drive motor
57.
[0084] An up/down feed nut 80 screws on to the middle section of
the up/down feed screw rod 78. The up/down feed nut 80 is formed
into a segmental annular ring shape using a metallic material such
as an iron-based metal having elasticity, and by adjusting the
interference in the screw section of the up/down feed screw rod 78
using a screw 81, it is possible to eliminate backlash movement in
this screw section. Moreover, the tip-end section of an engaging
arm 82, which is integrally provided on the up/down feed nut 80,
and the engaging hole 77 are joined together by way of a spherical
joint 83 so that force can be transmitted in the up/down direction,
and so that pivotal displacement is possible. The spherical joint
83 has a spherical engaging section 84 that is formed on the
tip-end section of the engaging arm 82 and has an outer
circumferential surface of a partial spherical convex surface, and
a spacer 85 that is formed into a cylindrical shape using a
material such as synthetic resin that slides easily has an inner
circumferential surface of a partial spherical concave surface. A
screw hole is formed in the center of the spherical engaging
section 84, and a slit is provided in the radial direction thereof
so that the outer diameter of the spherical engaging section 84 can
expand and contract elastically. More specifically, by causing a
partial conical shaped convex surface that is formed on the head
section of an adjustment screw 86 that is screwed into a screw hole
in the spherical engaging section 84 to engage with a partial
conical shaped concave surface that is formed in the opening of the
screw hole in the spherical engaging section 84, it is possible to
adjust the outer diameter of the spherical engaging section 84. By
screwing the adjustment screw 86 a proper amount into the screw
hole in the spherical engaging section 84, the occurrence of a gap
in the spherical joint 83 is prevented. With this kind of
construction, movement in the up/down direction is transmitted from
the up/down feed nut 80 to the bottom-end section of the holding
frame 73 without backlash movement.
[0085] As illustrated in FIG. 7 and FIG. 9, reinforcement ribs 90
are provided on both the left and right sides of the front-end
section of the vehicle body side bracket 32, and these
reinforcement ribs 90 maintain the strength and rigidity of the
portion of the vehicle body side bracket 32 where the tilt axes 33
are located. Moreover, in order to pivotally support the column
holder 81 by the tilt axes 33, reinforcement ribs 92 are also
provided in the front-end section of the column holder 31 between a
pair of left and right pivot support arm sections 91 that are
provided on the front-end section of the column holder 31, and the
main body of the column holder 31, and the strength and rigidity of
these pivot support arm sections 91 is maintained. Therefore, in
this example, the strength and rigidity of the pivotal support
section for supporting the column holder 31 by the vehicle body
side bracket 32 is sufficiently maintained, and the feel of
operation when operating the steering wheel 1 is sufficiently
prevented from becoming bad due to insufficient rigidity of this
pivotal support section.
[0086] In the following, position adjustment of the steering wheel
using the electric position adjustment apparatus for a steering
wheel of this example will be explained. First, when adjusting the
forward/backward position of the steering wheel 1, current flows to
the forward/backward electric drive motor 56, and the
forward/backward electric drive motor 56 rotates the
forward/backward feed screw rod 58 a specified amount in a
specified direction. As a result, the moving piece 16a moves in the
forward/backward direction along the forward/backward feed screw
rod 58, and by way of the transmission member 17a, the steering
column 5b moves in the forward/backward direction on the inside of
the column holder 31. As a result, the forward/backward position of
the steering wheel 1 is adjusted to a desired position. When the
steering wheel 1 is moved to an adjustable limit position, the
moving piece 16a comes in contact with one of a pair of stoppers
87a, 87b such as illustrated in FIG. 16 that are provided in the
portions near both ends of the forward/backward feed screw rod 58,
and further movement is prevented. In this state, current flowing
to the forward/backward electric drive motor 56 is stopped.
[0087] In a state where the forward/backward position of the
steering wheel 1 is adjusted to a limit position, the portions on
the end sections in the axial direction of the steering column 5b
that are fastened on the inside by an interference fit of the outer
rings 43a, 43b of the ball bearings 42a, 42b comes close to the
inner circumferential surface of the end section of the column
holder 31. There is a possibility that the end sections in the
axial direction of the steering column 5b may deform a little due
to fastening the outer rings 43a, 43b on the inside or due to the
effect of chucking during processing. However, the end sections in
the axial direction of the steering column 5b are reduced-diameter
sections 39a, 39b, and there is no rubbing between the end sections
in the axial direction of the steering column 5b and the inner
circumferential surface of the end sections of the column holder
31. Therefore, even when the forward/backward position of the
steering wheel 1 has been adjusted to the limit position,
uncomfortable noise or vibration does not occur due to rubbing
between the end section in the axial direction of the steering
column 5b and the inner circumferential surface of the end sections
of the column holder 31.
[0088] Next, when adjusting the up/down position of the steering
wheel 1, electric current flows to the up/down electric drive motor
57, and the up/down electric drive motor 57 rotates the up/down
feed screw rod 78 a specified amount in a specified direction. As a
result, the up/down feed nut 80 moves in the up/down direction
along and relative to the up/down feed screw rod 78. However, the
up/down feed nut 80 does not move in the up/down direction due to
the engagement of the engaging hole 77 and spherical engaging
section 84, so the up/down feed screw rod 78 moves in the up/down
direction, and as this happens, the actuator casing 53 and column
holder 31 that support the up/down feed screw rod 78 pivotally
displaces around the tilt shafts 33. As a result, the up/down
position of the steering wheel 1 is adjusted to a desired position.
In this case as well, when the steering wheel 1 is moved to an
adjustable limit position, the up/down feed nut 80 comes in contact
with one of a pair of stoppers 88a, 88b as illustrated in FIG. 17
that are provided in the portions near both ends of the up/down
feed screw rod 78, and further movement is prevented. In this
state, electric current flowing to the up/down electric drive motor
57 is stopped.
[0089] In the electric position adjustment apparatus for a steering
wheel of this example, the steering shaft 2b and the steering
column 5b are integrally constructed so that in at least the normal
state the entire length does not extend or contract, so the
rigidity of the steering shaft 2b and the steering column 5b is
sufficiently maintained. Therefore, it is possible to suppress
handle vibration and improve the steering performance. Moreover, a
single steering shaft 2b is arranged inside a non-divided steering
column 5b in this way, so joined section that are the cause of
backlash movement do not exist in the portion of the steering
column apparatus. Therefore, the occurrence of backlash movement in
the portion of the steering column apparatus is suppressed, and it
is possible to increase the resonant frequency of this portion. As
a result, it becomes possible to avoid resonance with traveling
vibration having a low resonant frequency, or with the engine
vibration in a state of large oscillation.
[0090] The pair of sliding plates 35, that are maintained in series
at two longitudinally spaced locations of the column holder 31
which holds the steering column 5b so as to displace in the axial
direction, elastically presses the middle cylindrical section 40 of
the steering column 5b toward the inner circumferential surface of
the column holder 31, so backlash movement between the steering
column 5b and the column holder 31 is also eliminated.
Particularly, by bringing the outer circumferential surface of the
middle cylindrical section 40 that has a relatively large diameter
in contact with the sliding plates 35, the contact area between
these members becomes large, so it is possible to make the force by
which the sliding plates 35 press the steering column 5b relatively
small. Moreover, the interval in the axial direction between the
portions where the sliding plates 35 press the outer
circumferential surface of the steering column 5b can be kept large
by the amount that the steering column 5b moves in the
forward/backward direction, so the rigidity of the engaging section
between the steering column 5b and the column holder 31 is
sufficiently maintained. Furthermore, by utilizing the moment that
occurs between the sliding section between the sliding plates 35
and the outer circumferential surface of the steering column 5b, it
is also possible to make the pressing force of the sliding plates
35 against the steering column 5b relatively small. With this kind
of construction, the load that occurs when moving the steering
wheel 1 in the forward/backward direction can be made small, so it
is possible to reduce the operating sound of the forward/backward
electric drive motor 56. Moreover, even when the tolerance of the
inner diameter dimension of the column holder 31 and the tolerance
of the outer diameter dimension of the steering column 5b are the
same as before, it is possible to eliminate backlash movement, and
thus it is possible to keep tilting of the steering column 5b and
the transmission member 17a small. Therefore, it is not necessary
to use a spherical shape having high displacement absorbency for
the tip-end section of the transmission member 17a, and it is
possible to use a simple shape such as a circular column shape.
[0091] In the apparatus of this example, construction is such that
the entire length of the steering shaft 2b and the steering column
5b does not extend or contract, so as the forward/backward position
of the steering wheel 1 is adjusted, the universal joint 27a and
the center position of the joint spider 34, which is the center of
displacement of the universal joint 27a, displace in the axial
direction of the steering shaft 2b and steering column 5b. On the
other hand, when adjusting the forward/backward position of the
steering wheel 1, the installation positions of the tilt shafts 33
that are provided between the front-end section of the column
holder 31 and the front-end section of the vehicle body side
bracket 32 do not change even though the forward/backward position
of the steering wheel 1 is adjusted.
[0092] Therefore, depending on the forward/backward position of the
steering wheel 1, the center position of the joint spider 34 is not
positioned on the center line of the tilt shaft 33. In this state,
when the column holder 31 is pivotally displaced around the tilt
shafts 33 in order to adjust the up/down position of the steering
wheel 1, the center position of the joint spider 34 pivotally
displaces around the tilt shafts 33. Due to this kind of pivotal
displacement of the center position of the joint spider 34, the
distance between the rear side universal joint 27a that includes
this joint spider 34 and the front side universal joint 27b
changes. The change in this distance is absorbed by the extension
or contraction of the intermediate shaft 28. However, in order to
extend or contract the intermediate shaft 28, a force that
overcomes the friction resistance that acts in the engaging section
between the intermediate inner shaft 29 and the intermediate outer
shaft 30 is necessary. Due to this kind of friction resistance, the
resistance against the pivotal displacement of the column holder 31
becomes large, and there is a possibility that smooth adjustment of
the up/down position of the steering wheel 1 will be hindered. The
extent that this smooth operation is hindered becomes more extreme
the greater the amount that the intermediate shaft extends or
contracts when the up/down position is adjusted, and the larger the
resistance is that occurs as the intermediate shaft 28 is extended
or contracted.
[0093] In the construction of this example, the center line O.sub.C
of the tilt shafts 33 is located in the center position in the
forward/backward direction between the center position O.sub.F of
displacement on the front-end side and the center position O.sub.B
of displacement on the rear-end side. Therefore, even in a state
where the center position of the joint spider 34 is not positioned
on the center line O.sub.C of the tilt shafts 33, it is possible to
keep the radius of the pivotal displacement of the center position
of the joint spider 34 due to pivotal displacement of the column
holder 31 around the tilt shafts 33 small. By keeping this radius
small, it is possible to keep the amount of extension or
contraction of intermediate shaft 28 due to adjustment of the
up/down position small, and it is possible to keep that resistance
during extension or contraction of the intermediate shaft 2 small.
As a result, it becomes possible to smoothly perform up/down
position adjustment of the steering wheel 1 regardless of the
forward/backward position of the steering wheel 1.
[0094] In FIG. 18, the positions represented by F, C and B
illustrate the displacement center positions of the universal joint
27a in the states when the steering wheel 1 is moved to the
adjustable front-end position, center position and rear-end
position, with the up/down position of the steering wheel being the
neutral state. With the forward/backward position of the steering
wheel 1 at the center position, and with the center position of
displacement of the universal joint 27a located on the center line
of the tilt shafts 33, the intermediate shaft 28 does not extend or
contract, and the universal joint 27a does not raise or lower as
the up/down position of the steering wheel 1 is adjusted.
Therefore, the intermediate shaft 28 and the universal joint 27a do
not resist adjustment of the up/down position of the steering wheel
1.
[0095] On the other hand, when adjusting the up/down position in a
state where the steering wheel 1 has moved to the front-end
position indicated by F, the center position of displacement of the
universal joint 27a displaces between f.sub.H and f.sub.L with
f.sub.O being the center, and the intermediate shaft 28 extends or
contracts due to this displacement. As can be seen from FIG. 18,
the amount of extension or contraction between f.sub.H and f.sub.L
becomes relatively large. The amount of extension or contraction
increases the longer is the distance from the tilt axes 33 to the
center position of displacement of the universal joint 27a. In the
construction of this example, by placing the position of the center
line O.sub.C of the tilt axes 33 at the middle position between the
center position of displacement O.sub.F on the front-end side and
the center position of displacement O.sub.B on the rear-end side,
it is possible to suppress the maximum value of the distance that
the center position of displacement of the universal joint 27a is
separated from the tilt axes 33 when compared with construction in
which the center line O.sub.C is located further toward the rear
than the center position of displacement O.sub.B on the rear-end
side. Therefore, even in the case where the up/down position of the
steering wheel 1 is adjusted with the steering wheel 1 moved to the
forefront position, the amount of extension or contraction is kept
small, and adjustment of the up/down position can be performed
smoothly.
[0096] On the other hand, in the state where the steering wheel 1
is moved to the rear-end position indicated by B, the universal
joint 27a that connects the front-end section of the steering shaft
2b and the rear-end section of the intermediate shaft 28 is located
further toward the rear than the tilt axes 33. When adjusting the
up/down position in this state, the center position of displacement
of the universal joint 27a displaces between b.sub.H and b.sub.L,
with b.sub.O as the center, and the intermediate shaft 28 extends
or contacts due to this displacement. As can be seen from FIG. 18,
the amount of extension or contraction is kept relatively small.
Instead, when adjusting the up/down position of the steering wheel
1, the portion that includes the universal joint 27a becomes the
load of the up/down electric drive motor 57 of the electric
actuator for up/down position adjustment. This is because, unlike
in the case when the universal joint 27a is further toward the
front than the tilt axes 33, the weight of the portion of the
universal joint 27a is not offset by the other portions. Therefore,
the load on the up/down electric drive motor 57 during adjustment
of the up/down position of the steering wheel 1 becomes large, and
the need for the use of a larger motor becomes disadvantageous for
making the electric position adjustment apparatus for a steering
wheel more compact and lightweight. This tendency becomes more
severe the greater the distance that the universal joint 27a is
separated toward the rear from the tilt axes 33 becomes. However,
in this example, the positional relationship of the center line
O.sub.C of the tilt axes 33 and the center positions of
displacement O.sub.F, O.sub.B is regulated as described above, so
when compared with construction in which the center line O.sub.C is
located further toward the front than the center position of the
displacement O.sub.F, it is possible to suppress the maximum value
of the distance that the universal joint 27a is separated toward
the rear from the tilt axes 33. Therefore, the extent that the load
on the up/down electric drive motor 57 becomes large can be
suppressed, and it becomes easy to make the apparatus more compact
and lightweight.
[0097] Locating the center line O.sub.C of the tilt axes 33 at the
middle position in the forward/backward direction is also
advantageous from the aspect of suppressing torque fluctuation of
the torque required for operating the steering wheel 1. In other
words, the cross-axis universal joints 27a, 27b are such that when
transmitting torque in a state in which a joint angle is applied,
the torque characteristic (torque loss) changes in correspondence
with the phase change in the rotational direction thereof. When
such change in the torque characteristic is left as is, a strange
feeling is given to the driver that operates the steering wheel 1.
Therefore, by suitably making the phase in the rotational direction
of the universal joints 27a, 27b different, the changes in the
torque characteristics of these universal joints 27a, 27b offset
each other. In this case, it is necessary that the relationship
between the joint angles of the universal joints 27a, 27b and the
shift in phase in the rotational direction be made suitable,
however, in the construction of this example, the position of
universal joint 27a on the rear side shifts due to the
forward/backward position adjustment of the steering wheel 1. As a
result, the relationship between the joint angles of the universal
joints 27a, 27b shifts from the initial relationship. When this
shift is large, the change in the torque characteristic of these
universal joints 27a, 27b cannot be sufficiently suppressed, and
there is a possibility that this will give the driver that is
operating the steering wheel 1 a strange feeling. However, in the
construction of this example, this shift can be kept small, so it
is possible to keep the possibility of giving the driver that
operates the steering wheel 1 a strange feeling small.
[0098] Moreover, the sliding plate 35 presses the steering column
5b downward toward the forward/backward feed screw apparatus 54, so
no moment is generated in the horizontal direction due to this
pressure, and as the forward/backward feed screw apparatus 54
operates and stops, backlash movement of the steering column 5b
inside the column holder 31, and up/down movement of the steering
column 5b during inversion of the displacement operation are
suppressed. Even when it is necessary to perform a finishing
process of the outer circumferential surface of the middle
cylindrical section 40 in order to improve the precision of the
engagement between the outer circumferential surface of the
steering column 5b and the inner circumferential surface of the
column holder 31, the outer circumferential surface of the middle
cylindrical section 40 has the largest diameter of the outer
circumferential surface of the steering column 5b, so the finishing
process of the outer circumferential surface of this middle
cylindrical section 40 is not hindered by the other parts, and can
be performed easily and efficiently. Moreover, the support rigidity
of the steering wheel 1 can also be easily adjusted by changing the
thickness of the metal plate of the steering column 5b and steering
shaft 2b. Furthermore, the portion of the steering column 5b that
is pressed by the sliding plates 35 is located in portion of the
steering column 5b having the largest diameter, so the surface area
of this pressed portion can be increased, and thus it is not
necessary to make the pressure force of the sliding plates 35 on
the steering column 5b excessively large. The effect of suppressing
backlash movement can be obtained with a small pressure force such
as this, so the load during operation is stable and small, and it
is also possible to reduce the operating sound of the
forward/backward electric drive motor 56.
[0099] In the construction of this example, the shape of the
transmission member 17 and cylindrical spacer 72 for transmitting
the movement of the moving piece 16a of the forward/backward feed
screw apparatus 54 to the steering column 5b is simple, so it is
possible to manufacture the transmission member 17a and cylindrical
spacer 72 with good precision and at low cost by cold forging.
[0100] Moreover, the relative displacement in the axial direction
of the transmission member 17a between this transmission member 17a
and the moving piece 16a is compensated for at two locations; the
inner circumferential surface and outer circumferential surface of
the cylindrical spacer 72, and the outer circumferential surface of
the tip-end section of the transmission member 17a and the inner
circumferential surface of the concave engaging section 19a that is
provided on the moving piece 16a. Therefore, due to the bad
precision on the contact surface of the bottom surface of the
column holder 31 and the top surface of the actuator casing 53, the
direction of movement of the moving piece 16a and the direction of
movement of the steering column 5b during forward/backward position
adjustment of the steering wheel 1 become non-parallel, and even
when the transmission member 17a and the moving piece 16a displace
relative to each other in the axial direction of transmission
member 17a along with the forward/backward position adjustment,
there is rubbing at two locations, so the rubbing lengths can be
made short, and thus it is possible to suppress the occurrence of
strange noise and vibration. Furthermore, there are no neck
sections, which are disadvantageous from the aspect of maintaining
strength and rigidity, in the transmission member 17a, so the
durability and reliability of the forward/backward feed screw
apparatus 54 is maintained.
[0101] Furthermore, in the construction of this example, the
up/down feed screw rod 78 of the up/down feed screw apparatus 55 is
located directly below the column holder 31 in the radial direction
of the column holder 31, so when adjusting the up/down position of
the steering wheel 1, no harmful moment is applied to the column
holder 31. Therefore, it is possible to smoothly perform this
up/down position adjustment. From the aspect of maintaining support
rigidity of the column holder 31 and also maintaining the support
rigidity of the steering wheel 1, preferably the holding frame 73
for guiding the up/down position adjustment is located as far as
possible to the rear within a range so as not to interfere with the
portion that is fastened to the steering column 5b regardless of
forward/backward movement of the steering column during
forward/backward position adjustment of the steering wheel 1.
Moreover, in order to smoothly perform up/down adjustment of the
steering wheel 1, preferably a lubricant such as grease or the like
is applied to the sliding plates 75a, 75b. Furthermore, from the
aspect of being able to smoothly perform adjustment of the steering
wheel 1 in the up/down direction and forward/backward direction,
and to keep the installation space of the forward/backward feed
screw apparatus 54 and up/down feed screw apparatus 55 small,
preferably the up/down feed screw rod 78 and the forward/backward
feed screw rod 58 are located in directions such that the
respective center axes are orthogonal to each other.
Second Example
[0102] FIG. 19 and FIG. 20 illustrate a second example of an
embodiment of the present invention. This example is of the case in
which the construction of the present invention is applied to the
second example of conventional structure. In this example, a
steering shaft 2a is composed of a cylindrical outer shaft 3a, and
a circular rod shaped inner shaft 4a that is inserted into the
outer shaft 3a so as to be able to slide in the axial direction and
so as to be able to transmit rotational force. Moreover, a steering
column 5c of a column unit of the present invention is composed of
a cylindrical outer column 6c that is supported by an installation
bracket 14, and a cylindrical inner column 7c that is inserted
inside the outer column 6c so as to be able to slide in the axial
direction. The steering shaft 2a is supported on the inside of the
steering column 5c so as to be able to rotate freely, and the outer
shaft 3a and inner column 7c move in the forward/backward direction
relative to the inner shaft 4a and outer column 6c. In this
example, the outer column 6c corresponds to a support section of
the column unit of the present invention, and the inner column 7c
corresponds to an adjusted section of the column unit of the
present invention.
[0103] As illustrated in FIG. 19, in this example, in order to
eliminate backlash movement of the inner column 7c with respect to
the outer column 6c, retaining holes 22b are formed at two
locations that are separated in the forward/backward direction in
the top surface of the outer column 6c so as to connect the inner
circumferential surface and outer circumferential surface of the
outer column 6c. On the inside of each retaining hole 22b, in order
from the inside, there is a sliding plate 35, a washer 36 and a
disc spring 37, and the opening on the top end of each retaining
hole 22b is covered by a screw cap 38. In this state, the sliding
plate 35 that is located in the inner side end section of each
retaining hole 22b presses against the outer circumferential
surface (top surface) of the inner column 7c by way of the elastic
force from the disc spring 37.
[0104] In this example, construction is such that a linear motion
ultrasonic motor 15a that is supported by the bottom end section of
an installation bracket 14 causes the inner column 7c to displace
in the axial direction with respect to the outer column 6c. A
moving piece 16b that is provided in the linear motion ultrasonic
motor 15a so as to be able to move in the axial direction
(forward/backward direction) of the steering column 5c has a base
section 60a that is connected to the linear motion ultrasonic motor
15a, and a connecting section 61a that is provided above the base
section 60a, and there is a concave engaging section 19b provided
in the center section of this connecting section 61a.
[0105] In this example as well, a transmission member 17a is such
that there is a male screw section 63 on the top-end section, an
outwardly protruding flange-shaped rim section 64 in the middle
section, and a circular column section 66 on the bottom-end
section. In a state with a ring spacer 71 being held between top
surfaces of an inner side spacer 69 and an outer side spacer 70
that are located on the top surface of the rim section 64 and the
inner column 7c, the transmission member 17a is fastened by screws
to the inner column 7c. The circular column section 65 of the
transmission member 17a is placed inside the concave engaging
section 19b of the moving piece 16b by way of the cylindrical
spacer 72 such that there is no backlash movement, and is able to
slide in the axial direction of the transmission member 17a.
[0106] The concave engaging section 19b of the moving piece 16b has
a cylindrical concave-shaped inner-circumferential surface whose
inner diameter does not change in the axial direction of the
transmission member 17a, and the circular column section 65 on the
tip-end section of the transmission member 17a has a cylindrical
convex-shaped outer-circumferential surface whose outer diameter
does not change in the axial direction of the transmission member
17a, and the cylindrical spacer 72 has a cylindrical convex-shaped
outer-circumferential surface whose outer diameter does not change
in the axial direction of the transmission member 17a and a
cylindrical concave-shaped inner-circumferential surface whose
inner diameter does not change in the axial direction of the
transmission member 17a. The other construction and functions of
this example are the same as in the first example of an
embodiment.
INDUSTRIAL APPLICABILITY
[0107] The electric position adjustment apparatus for a steering
wheel of the present invention, as in the embodiment descried
above, is suitably applied to an electric tilt telescopic steering
apparatus that is able to perform adjustment of not only the
forward/backward position of a steering wheel, but also perform
adjustment of the up/down position. However, the electric position
adjustment apparatus for a steering wheel of the present invention
can also be applied to an electric telescopic steering apparatus
that does not have a tilt mechanism and is constructed so as to
only be able to adjust the forward/backward position of the
steering wheel. Moreover, the construction for installation in a
vehicle, and the construction for connecting the steering shaft and
universal joints are also not limited, and the present invention
can be widely applied to an electric position adjustment apparatus
for a steering wheel that is assembled in an electric steering
apparatus for which various kinds of previously known structure are
employed.
EXPLANATION OF REFERENCE NUMBERS
[0108] 1 Steering wheel [0109] 2, 2a, 2b Steering shaft [0110] 3,
3a Outer shaft [0111] 4, 4a Inner shaft [0112] 5, 5a, 5b, 5c
Steering column [0113] 6, 6a, 6b, 6c Outer column [0114] 7, 7a, 7b,
7c Inner column [0115] 8 Gear housing [0116] 9 Feed nut [0117] 10
Push-pull arm [0118] 11 Push-pull rod [0119] 12 Male screw section
[0120] 13 Worm reduction gear [0121] 14 Installation bracket [0122]
15, 15a Linear motion ultrasonic motor [0123] 16, 16b Moving piece
[0124] 16a Moving piece (forward/backward feed nut) [0125] 17, 17a
Transmission member [0126] 18 Spherical joint [0127] 19, 19a, 19b
Concave engaging section [0128] 20 Spacer [0129] 21 Spherical
engaging section [0130] 22, 22a, 22b Retaining hole [0131] 23
Female screw [0132] 24 Adjustment screw [0133] 25 Disc spring
[0134] 26 Pad [0135] 27a, 27b Universal joint [0136] 28
Intermediate shaft [0137] 29 Intermediate inner shaft [0138] 30
Intermediate outer shaft [0139] 31 Column holder [0140] 32 Vehicle
body side bracket [0141] 33 Tilt shaft [0142] 34 Joint spider
[0143] 35 Sliding plate [0144] 36 Washer [0145] 37 Disc spring
[0146] 38 Screw cap [0147] 39a, 39b Reduced-diameter section [0148]
40 Middle cylindrical section [0149] 41a, 41b Inclined surface
section [0150] 42a, 42b Ball bearing [0151] 43a, 43b Outer ring
[0152] 44a, 44b Inner ring [0153] 45 Retaining ring [0154] 46 Push
nut [0155] 47 Elastic material [0156] 48 Screw hole [0157] 49
Installation plate section [0158] 50 Long hole [0159] 51 Notch
[0160] 52a, 52b Sliding plate [0161] 53 Actuator casing [0162] 54
Forward/backward feed screw apparatus [0163] 55 Up/down feed screw
apparatus [0164] 56 Forward/backward electric drive motor [0165] 57
Up/down electric drive motor [0166] 58 Forward/backward feed screw
rod [0167] 59a, 59b Ball bearing [0168] 60, 60a Base section [0169]
61, 61a Connecting section [0170] 62 Screw hole [0171] 63 Male
screw section [0172] 64 Rim section [0173] 65 Circular column
section [0174] 66 Engaging hole [0175] 67 Through hole [0176] 68
Nut plate [0177] 69 Inner side spacer [0178] 70 Outer side spacer
[0179] 71 Ring spacer [0180] 72 Cylindrical shaped spacer [0181] 73
Holding frame [0182] 74a, 74b Convex section [0183] 75a, 75b
Sliding plate [0184] 76 Pressure screw [0185] 77 Engaging hole
[0186] 78 Up/down feed screw rod [0187] 79a, 79b Ball bearing
[0188] 80 Up/down feed nut [0189] 81 Screw [0190] 82 Engaging arm
[0191] 83 Spherical joint [0192] 84 Spherical engaging section
[0193] 85 Spacer [0194] 86 Adjustment screw [0195] 87a, 87b Stopper
[0196] 88a, 88b Stopper [0197] 89 Long hole in the forward/backward
direction [0198] 90 Reinforcement rib [0199] 91 Pivot support arm
section [0200] 92 Reinforcement rib
* * * * *