JP2014084002A - Steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steering device capable of suppressing increase of backlash due to urging by a rack bush.SOLUTION: A steering device 1 has a rack shaft 6 penetrating a housing 3. A first pinion 7 of a first pinion shaft 8 for transmission of a steering auxiliary force is engaged in a first rack 4, and a second pinion 9 of a second pinion shaft 10 for transmission of a manual steering force is engaged in a second rack 5. The second pinion shaft 10 is arranged on the same side as the first pinion shaft 8 with respect to the plane including the central axis line CR of the rack shaft 6 and being in parallel with the central axis line C1 of the first pinion shaft 8. In a first end part of the rack shaft 6 relatively close to the second rack 5, a first rack bush 16 urging the rack shaft 6 toward the side of the first pinion 7 is arranged. Between the pinion shafts 8 and 10 in the axis direction X1 of the rack shaft 6, a second rack bush 17 urging the rack shaft 6 toward the side of both the pinions 7 and 9 is arranged.

Description

  The present invention relates to a steering device.

In a rack-and-pinion type steering device, a two-pinion type in which a main pinion that transmits a manual steering force from a handle and an auxiliary pinion that transmits a steering assist force by an electric motor are respectively meshed with a corresponding rack of a rack shaft. A steering apparatus has been proposed.
Typically, the pair of ends of the rack shaft are supported by a rack bush held by the housing so as to be slidable in the axial direction. In Patent Document 1, of the pair of end portions of the rack shaft, the end portion closer to the auxiliary pinion is received by an eccentric bearing bush as a rack bush. The eccentric bearing bush adjusts the meshing state between the auxiliary pinion and the rack shaft by changing the position where the rack shaft is pivotally supported by the rotation position.

Japanese Utility Model Publication No. 64-18977

The biasing force of the rack bush (eccentric bearing bush) that supports the end of the rack shaft on the side close to the auxiliary pinion exerts a bending moment on the rack shaft with the meshing portion of the auxiliary pinion and the rack shaft serving as a fulcrum. As a result, the backlash of the meshing portion between the main pinion and the rack shaft is increased, the meshing is weakened, and noise due to the meshing sound may be generated.
Accordingly, an object of the present invention is to provide a steering device that can suppress an increase in backlash due to the biasing of the rack bush.

  In order to achieve the object, the invention of claim 1 has a first end (11) and a second end (12) which are inserted through the housing (3) and face in the axial direction (X1). The first rack (4) that is relatively close to the first end portion of these both end portions and the second rack (5) that is relatively close to the second end portion of both end portions are set to a central axis (CR). A rack shaft (6) on the same side, a first pinion shaft (8) having a first pinion (7) meshing with the first rack, and a second pinion (9) meshing with the second rack are provided. A second pinion shaft (10) disposed on the same side as the first pinion shaft with respect to a plane including the central axis of the rack shaft and parallel to the central axis (C1) of the first pinion shaft. The rack shaft is held by the housing from the back of the first rack to the first pin. A first rack guide (39) that biases toward the on side, and a second rack guide that is held by the housing and biases the rack shaft from the back of the second rack toward the second pinion. (49) and a first rack bush (16) supported by the housing, supporting the first end portion of the rack shaft so as to be slidable in the axial direction, and biasing the rack shaft toward the first pinion. And a second rack that is supported by the housing, slidably supports the first end of the rack shaft in the axial direction, and biases the rack shaft toward the first pinion and the second pinion. Provided is a steering device (1) comprising a bush (17).

In addition, although the alphanumeric character in a parenthesis represents the corresponding component etc. in embodiment mentioned later, this does not mean that this invention should be limited to those embodiment as a matter of course. The same applies hereinafter.
The second rack bush may be arranged between the first pinion shaft and the second pinion shaft in the axial direction of the rack shaft.

  According to a third aspect of the present invention, the first pinion shaft is for transmitting a steering assist force, the second pinion shaft is for transmitting a manual steering force, and the first rack is used as a bearing that supports the rack shaft. Only the bush and the second rack bush may be provided.

  According to the first aspect of the present invention, the urging force by the first rack bush, which is disposed at the first end of the rack shaft and urges the rack shaft toward the first pinion, is generated between the first pinion and the first rack guide. A moment in the direction of pulling the rack shaft away from the second pinion is generated with the position where the rack shaft is sandwiched as a fulcrum. The second rack bush urges the rack shaft toward both pinions against the moment caused by the first rack bush, and therefore, an increase in backlash between the second pinion and the second rack is suppressed. Can do.

  Specifically, as in claim 2, the second rack bush disposed between the first pinion shaft and the second pinion shaft with respect to the axial direction of the rack shaft includes the first pinion and the first rack guide. A moment against the moment caused by the first rack bush is generated with the position where the rack shaft is sandwiched as a fulcrum. As a result, an increase in backlash between the second pinion and the second rack can be reliably suppressed.

  According to invention of Claim 3, there exists the following effect. That is, if a rack bush is disposed at the second end of the rack shaft that is relatively close to the second pinion for manual steering force transmission, the rack bush is far away from the fulcrum. A large moment is generated around the center. The first rack bush generates a large reaction force moment component against the large moment. Therefore, both the rack bush and the first rack bush arranged at the second end portion generate a large frictional resistance with respect to the rack shaft, and the steering feeling may be deteriorated. On the other hand, in the present invention, since the rack bush is not disposed at the second end, an increase in frictional resistance against the movement of the rack shaft can be suppressed, and a good steering feeling can be obtained.

1 is a schematic view of a steering device according to an embodiment of the present invention. FIG. 2 is a schematic side view of a rack shaft and both pinion shafts in the steering apparatus of FIG. 1, showing an arrangement mode of both pinion shafts as viewed from the axial direction of the rack shaft. It is a typical side view of a rack shaft and both pinion shafts, and shows a modified example of the arrangement mode of both pinion shafts as viewed from the axial direction of the rack shaft. It is a schematic front view of a rack shaft and both pinion shafts, and shows a modification of the arrangement of both pinion shafts as viewed from a direction orthogonal to both the central axis of the rack shaft and the central axis of the first pinion shaft. FIG. 2 is a schematic cross-sectional view of a main part of the steering device of FIG. 1, showing a cross section cut along a central axis of a first pinion shaft for transmitting a steering assist force. FIG. 2 is a schematic cross-sectional view of a main part of the steering device of FIG. 1, showing a cross section cut along a central axis of a second pinion shaft for manual steering force transmission. It is a schematic perspective view of a 1st rack bush. It is a schematic sectional drawing of the support structure by a 1st rack bush. It is sectional drawing which follows the 8B-8B line | wire of FIG. 8A, and has shown the relationship between the cyclic | annular part of a 1st rack bush, and a rack shaft. It is sectional drawing which follows the 8C-8C line | wire of FIG. 8A, and has shown the relationship between the cross-section circular arc-shaped part of a 1st rack bush, and a rack shaft. It is a schematic perspective view of a 2nd rack bush. It is a schematic sectional drawing of the support structure by a 2nd rack bush. It is sectional drawing which follows the 10B-10B line | wire of FIG. 10A, and has shown the relationship between the cyclic | annular part of a 2nd rack bush, and a rack shaft. It is sectional drawing which follows the 10C-10C line | wire of FIG. 10A, and has shown the relationship between the cross-section circular arc-shaped part of a 2nd rack bush, and a rack shaft. It is a schematic diagram of the structure which supports a rack axis | shaft in the steering apparatus of FIG. It is a schematic diagram of the structure which supports a rack axis | shaft in the steering apparatus of the reference form of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic view of a steering apparatus according to an embodiment of the present invention. Referring to FIG. 1, a steering device 1 includes a steering mechanism 2 including a rack and pinion mechanism. The steering mechanism 2 is inserted into a cylindrical first housing 3 (corresponding to a rack housing) fixed to the vehicle body, and a first rack 4 of a helical tooth spaced apart in the axial direction X1 and a second rack of helical teeth. 5, a rack shaft 6 as a turning shaft, a first pinion shaft 8 having a first pinion 7 of a helical tooth meshing with the first rack 4, and a second pinion of a helical tooth meshing with the second rack 5. 9 and a steered wheel 15 connected to a first end 11 and a second end 12 in the axial direction X1 of the rack shaft 6 via a tie rod 13 and a knuckle 14, respectively. .

The second pinion shaft 10 is for manual steering force transmission, and transmits the manual steering force applied by the driver to the steering member 18 such as a steering wheel. That is, the steering member 18 is connected to the second pinion shaft 10 via the steering shaft 19, the universal joint 20, the intermediate shaft 21, and the universal joint 22 so as to be able to transmit torque.
When the driver operates the steering member 18, the steering shaft 19, the universal joint 20, the intermediate shaft 21, the universal joint 22, the second pinion shaft 10, the rack shaft 6, and the tie rod 13 are generated by the manual steering force (steering torque). And the steered wheel 15 can be steered through the knuckle 14. That is, the steering member 18, the steering shaft 19, the universal joint 20, the intermediate shaft 21, the universal joint 22, the second pinion shaft 10, and the rack shaft 6 constitute a manual steering system MS.

The first pinion shaft 8 is for transmitting a steering assist force. That is, the steering device 1 includes a steering assist mechanism 23. The steering assist mechanism 23 includes an electric motor 24 that generates a steering assist force, and a speed reduction mechanism 25 such as a worm gear mechanism that reduces the rotational output of the electric motor 24 and transmits it to the first pinion shaft 8.
The electric motor 24 includes a motor housing 26 fixed to the vehicle body and a rotary shaft 27 as an output shaft. The speed reduction mechanism 25 includes a drive gear 29 such as a worm shaft connected to the rotary shaft 27 via a joint 28 so as to be able to transmit torque, and a worm wheel meshed with the drive gear 29 and connected to the first pinion shaft 8 so as to be integrally rotatable. Etc. and a driven gear 30 such as the above.

A torque sensor 31 that detects the steering torque applied to the steering member 18 is disposed at any position on the path from the steering shaft 19 to the second pinion shaft 10 of the manual steering system MS.
The torque detection result of the torque sensor 31 is given to an ECU (Electronic Control Unit) 32. The ECU 32 controls the drive of the electric motor 24 via a built-in drive circuit based on a torque detection result, a vehicle speed detection result given from a vehicle speed sensor (not shown), and the like. The output rotation of the electric motor 24 is decelerated via the speed reduction mechanism 25 and transmitted to the first pinion shaft 8 and converted into a linear motion of the rack shaft 6 to assist steering.

  The first rack 4 and the second rack 5 are provided on the same side of the center axis CR of the rack shaft 6, and the first pinion shaft 8 and the second pinion shaft 10 are in relation to the rack shaft 6. They are arranged on the same side (see also FIG. 11 which is a schematic diagram). Specifically, FIGS. 2 to 3 are schematic views of the rack shaft 6 viewed from the axial direction (in FIGS. 2 and 3, the direction orthogonal to the paper surface corresponds to the axial direction X1 of the rack shaft 6). As described above, the second pinion shaft 10 is disposed on the same side as the first pinion shaft 8 with respect to the plane PP including the central axis CR of the rack shaft 6 and parallel to the central axis C1 of the first pinion shaft 8. Yes.

  The first pinion shaft 8 and the second pinion shaft 10 are arranged substantially in parallel. Specifically, when viewed from the axial direction of the rack shaft 6, as shown in FIG. 2, the center axis C1 of the first pinion shaft 8 and the center axis C2 of the second pinion shaft 10 coincide, or As shown in FIG. 3, the absolute value | θ1 | of the angle θ1 formed by the central axis C1 of the first pinion shaft 8 and the central axis C2 of the second pinion shaft 10 is in a range of 0 <| θ1 | ≦ 30 °. The angle is set within.

  Further, when viewed from a direction orthogonal to both the center axis CR of the rack shaft 6 and the center axis C1 of the first pinion shaft 8, as shown in FIG. 1, the center axis C1 of the first pinion shaft 8 and the second axis The central axis C2 of the pinion shaft 10 is parallel, or the absolute value of the angle θ2 formed by the central axis C1 of the first pinion shaft 8 and the central axis C2 of the second pinion shaft 10 as shown in FIG. | Θ2 | is set to an angle within a range of 0 <| θ2 | ≦ 30 °.

Referring to FIG. 1 again, the rack shaft 6 is slid in the axial direction X1 by the first rack bush 16 and the second rack bush 17 which are held by the first housing 3 and separated in the axial direction X1 of the rack shaft 6. It is supported movably. In FIG. 1, the first rack bush 16 and the second rack bush 17 are schematically shown.
The first end 11 of the rack shaft 6 is relatively close to the first pinion shaft 8 and relatively far from the second pinion shaft 10. The second end 12 of the rack shaft 6 is the end opposite to the first end 11 and is relatively close to the second pinion shaft 10 and relatively far from the first pinion shaft 8.

The first rack bush 16 functions to support the first end 11 of the rack shaft 6 so as to be slidable in the axial direction X1 and to urge the rack shaft 6 toward the first pinion 7 side.
The second rack bush 17 is disposed between the pinion shafts 8 and 10 with respect to the axial direction X1 of the rack shaft 6. The second rack bush 17 functions to urge the rack shaft 6 toward the first pinion 7 and the second pinion 9.

More specifically, the second rack bush 17 is closer to the first pinion shaft 8 side than the center position P1 between the first pinion shaft 8 and the second pinion shaft 10 in the axial direction X1 of the rack shaft 6. Has been placed.
FIG. 5 is a schematic cross-sectional view of the main part of the steering device 1 cut along the central axis of the first pinion shaft 8 for transmitting the steering assist force. As shown in FIG. 5, a cylindrical second housing 33 that is continuous with the first housing 3 through which the rack shaft 6 is inserted is provided. The rack shaft 6 is inserted into the second housing 33, and the first pinion shaft 8 and the speed reduction mechanism 25 are accommodated.

The second housing 33 accommodates the drive gear 29 that is continuous with the main body 34, the main body 34 that houses the first pinion shaft 8 and the driven gear 30, the lid 35 that closes one end of the main body 34, and the main body 34. And a drive gear housing (not shown).
The first pinion shaft 8 is rotatably supported by a first bearing 36 made of, for example, a ball bearing supported by the lid portion 35 and a second bearing 37 made of, for example, a ball bearing supported by the main body portion 34. . The driven gear 30 is disposed between the first bearing 36 and the second bearing 37 with respect to the axial direction of the first pinion shaft 8. Moreover, the front-end | tip part of the 1st pinion shaft 8 is rotatably supported by the 3rd bearing 38 which consists of a needle roller bearing supported by the main-body part 34, for example. The first pinion 7 is arranged between the second bearing 37 and the third bearing 38 with respect to the axial direction of the first pinion shaft 8.

The steering device 1 is disposed on the opposite side of the first pinion shaft 8 with the rack shaft 6 interposed therebetween, and a first rack guide that biases the rack shaft 6 toward the first pinion 7 from the back of the first rack 4. 39 is provided.
The first rack guide 39 includes a cylindrical first guide housing 40 provided in the main body 34 of the second housing 33 and a first holding hole 41 in a first holding hole 41 formed in the first guide housing 40. And a first support yoke 42 that is slidably received in the depth direction Z1 and the opposite direction thereof and supports the rack shaft 6 so as to be slidable in the axial direction (direction orthogonal to the paper surface in FIG. 5). ing. The first rack guide 39 is received by the first adjustment screw 43 and fixed to the inlet of the first holding hole 41, and the first support yoke 42 is elastically moved toward the rack shaft 6 side. A first urging member 44 made of, for example, a compression coil spring to be urged, and a first lock nut 45 for fixing the first adjustment screw 43 to the first guide housing 40 are provided.

  The first adjustment screw 43 regulates the amount of the gap for moving the first support yoke 42 in the depth direction Z1 and the opposite direction (corresponding to the gap amount between the first adjustment screw 43 and the first support yoke 42). To do. The first urging member 44 presses the first rack 4 of the rack shaft 6 against the first pinion 7 of the first pinion shaft 8 via the first support yoke 42. As a result, a preload is applied to the meshing portion between the first rack 4 and the first pinion 7, and backlash is suppressed.

  Next, FIG. 6 is a schematic cross-sectional view of the main part of the steering device 1 cut along the central axis of the second pinion shaft 10 for manual steering force transmission. As shown in FIG. 6, a third housing 46 is provided to intersect the first housing 3 through which the rack shaft 6 is inserted. The rack shaft 6 is inserted into the third housing 46 and the second pinion shaft 10 is accommodated.

The second pinion shaft 10 is rotatable by a fourth bearing 47 made of, for example, a ball bearing supported by the third housing 46 and a fifth bearing 48 made of, for example, a needle roller bearing supported by the third housing 46. It is supported. The second pinion 9 is disposed between the fourth bearing 47 and the fifth bearing 48 in the axial direction of the second pinion shaft 10.
Further, the steering device 1 is disposed on the opposite side of the second pinion shaft 10 with the rack shaft 6 interposed therebetween, and a second rack that biases the rack shaft 6 toward the second pinion 9 from the back of the second rack 5. A guide 49 is provided.

  The second rack guide 49 includes a cylindrical second guide housing 50 provided in the third housing 46, and a depth direction of the second holding hole 51 in the second holding hole 51 formed in the second guide housing 50. Z2 and a second support yoke 52 that is slidably accommodated in the opposite direction and supports the rack shaft 6 so as to be slidable in the axial direction (a direction orthogonal to the paper surface in FIG. 6). The second rack guide 49 is elastically moved to the rack shaft 6 side by the second adjustment screw 53 screwed into the inlet of the second holding hole 51 and the second support screw 52 received by the second adjustment screw 53. A second biasing member 54 made of, for example, a compression coil spring that biases, and a second lock nut 55 that fixes the second adjustment screw 53 to the second guide housing 50 are provided.

  The second adjustment screw 53 regulates the amount of the gap for moving the second support yoke 52 in the depth direction Z2 and the opposite direction (corresponding to the gap amount between the second adjustment screw 53 and the second support yoke 52). To do. The second urging member 54 presses the second rack 5 of the rack shaft 6 against the second pinion 9 of the second pinion shaft 10 via the second support yoke 52. As a result, a preload is applied to the meshing portion between the second rack 5 and the second pinion 9, and backlash is suppressed.

One end of the second pinion shaft 10 protrudes from the third housing 46 through a lid member 56 screwed and fixed to an opening at one end of the third housing 46, and is not shown in FIG. Are coupled to the intermediate shaft 21 (see FIG. 1).
The first rack bush 16 that supports the first end 11 of the rack shaft 6 and urges the rack shaft 6 toward the first pinion 7 is provided on the first housing 3 as shown in FIGS. 7 and 8A. An annular portion 60 that is supported and surrounds the entire circumference of the first end portion 11 of the rack shaft 6, and a cross-sectional arc-shaped portion 61 that extends in the axial direction from the annular portion 60, are formed of resin, for example.

  As shown in FIG. 8B, which is a cross-sectional view taken along the line 8B-8B in FIG. The engaging projection 62 on the outer periphery 60 a of the annular portion 60 is engaged with an engaging recess 63 provided on the inner periphery 3 a of the first housing 3. The engagement between the engagement protrusion 62 and the engagement recess 63 restricts the rotation and axial movement of the first rack bush 16.

  As shown in FIG. 8C, which is a cross-sectional view taken along line 8C-8C in FIG. 8A, a plurality of chevron-shaped elastic convex portions 64, 65, 66 are provided in the axial direction on the inner periphery 61 a of the cross-section arc-shaped portion 61. It is formed as a protruding ridge. Each of the elastic convex portions 64, 65, 66 forms a flat surface that protrudes from a cylindrical surface that is a reference surface that constitutes the inner periphery 61 a of the circular arc-shaped portion 61. The elastic convex portion 64 is disposed at a central position between the elastic convex portion 65 and the elastic convex portion 66 in the circumferential direction of the rack shaft 6. For example, the elastic convex portion 64 is separated from the elastic convex portions 65 and 66 in the circumferential direction of the rack shaft 6 with an angular pitch of 45 degrees, for example.

The plurality of elastic convex portions 64 to 66 urge the rack shaft 6 toward the first pinion 7 in cooperation with each other. That is, the first rack bush 16 urges the rack shaft 6 toward the first pinion 7 side by the urging force F <b> 1 that is the resultant force of the plurality of elastic convex portions 64 to 66.
Further, the rack shaft 6 is attached to the first pinion 7 and the second pinion 9 side while supporting the rack shaft 6 by being arranged at an intermediate portion between both pinion shafts 8 and 10 in the axial direction X1 of the rack shaft 6. As shown in FIGS. 9 and 10A, the second rack bushing 17 is supported by the first housing 3 and surrounds the entire circumference of the intermediate portion of the rack shaft 6 in the axial direction X1, and the annular portion 70 And an arcuate section 71 that extends in the axial direction from, for example, is formed of resin.

  As shown in FIG. 10B, which is a cross-sectional view taken along the line 10B-10B in FIG. 10A, an engagement protrusion 72 that protrudes radially outward is provided on the outer periphery 70 a of the annular portion 70. The engaging projection 72 on the outer periphery 70 a of the annular portion 70 is engaged with an engaging recess 73 provided on the inner periphery 3 a of the first housing 3. The engagement between the engagement protrusion 72 and the engagement recess 73 restricts the rotation and axial movement of the first rack bush 16.

  As shown in FIG. 10C, which is a cross-sectional view taken along the line 10C-10C in FIG. It is formed as a protruding ridge. Each elastic convex portion 74, 75, 76 forms a flat surface that protrudes from a cylindrical surface that is a reference surface constituting the inner periphery 71 a of the circular arc-shaped portion 71. The elastic convex portion 74 is disposed at a central position between the elastic convex portion 75 and the elastic convex portion 76 in the circumferential direction of the rack shaft 6. For example, the elastic convex portion 74 is separated from the elastic convex portions 75 and 76 in the circumferential direction of the rack shaft 6 at an angular pitch of 45 degrees, for example.

The plurality of elastic convex portions 74 to 76 urge the rack shaft 6 toward the first pinion 7 and the second pinion 9 in cooperation with each other. That is, the second rack bush 17 urges the rack shaft 6 toward the first pinion 7 and the second pinion 9 by an urging force F2 that is a resultant force of the plurality of elastic convex portions 74 to 76.
According to the present embodiment, as shown in FIG. 11 which is a schematic view, the first rack bush 16 is arranged at the first end 11 of the rack shaft 6 and biases the rack shaft 6 toward the first pinion 7 side. The biasing force F1 generates a moment M1 in a direction in which the rack shaft 6 is pulled away from the second pinion 9 with the position P2 between which the rack shaft 6 is sandwiched between the first pinion 7 and the first rack guide 39 as a fulcrum. The second rack bush 17 urges the rack shaft 6 toward both the pinions 7 and 9 against the moment M1 due to the first rack bush 16, so that the second pinion 9 and the second rack 5 An increase in backlash can be suppressed.

  Specifically, that is, the second rack bush 17 disposed between the first pinion shaft 8 and the second pinion shaft 10 with respect to the axial direction X1 of the rack shaft 6 includes the first pinion 7 and the first rack guide 39. As a result, a moment M2 that opposes the moment M1 due to the first rack bush 16 is generated with the position P2 sandwiching the rack shaft 6 as a fulcrum. Thereby, an increase in backlash between the second pinion 9 and the second rack 5 can be reliably suppressed.

  The first pinion shaft 8 is for transmitting steering assist force, the second pinion shaft 10 is for transmitting manual steering force, and the bearings that support the rack shaft 6 are the first rack bush 16 and the second rack bush. Since only 17 is provided, there are the following advantages. In other words, if a rack bush is disposed at the second end 12 of the rack shaft 6 that is relatively close to the second pinion 9 for manual steering force transmission, the rack bush is separated from the fulcrum (position P2). Since the distance is long, a large moment is generated around the fulcrum. The first rack bush generates a large reaction force moment component against the large moment. Therefore, the rack bush and the first rack bush 16 arranged at the second end 12 both generate a large frictional resistance with respect to the rack shaft 6, and the steering feeling may be deteriorated. On the other hand, in this embodiment, since the rack bush is not arranged at the second end portion 12, an increase in frictional resistance against the movement of the rack shaft 6 is suppressed, and a good steering feeling is obtained. Can do.

  FIG. 12 schematically shows a support structure for the rack shaft 6R of the steering device 1R according to the reference embodiment of the present invention. Referring to FIG. 12, the present embodiment is different from the embodiment of FIG. 11 as follows. That is, in the embodiment of FIG. 11, the first rack 4 and the second rack 5 are provided on the same side with respect to the central axis CR of the rack shaft 6, and the first pinion shaft 8 and the second pinion shaft 10 are Are arranged on the same side with respect to the rack shaft 6.

  On the other hand, in the present embodiment, the first rack 4R and the second rack 5 are provided on the opposite sides of the center axis CR of the rack shaft 6, and the first pinion shaft for transmitting the steering assist force is provided. 8R and the second pinion shaft 10 for transmitting a manual steering force are arranged on the opposite side with the rack shaft 6 interposed therebetween. The first pinion 7R of the first pinion shaft 8R is engaged with the first rack 4R. The first rack bush 16R disposed at the first end portion 11R of the rack shaft 6R generates a biasing force F3 that biases the rack shaft 6 toward the first pinion 7R. A second rack bush 17R disposed between the pinion shafts 8R and 10 with respect to the axial direction X1 of the rack shaft 6 generates a biasing force F4 that biases the rack shaft 6 toward the first pinion 7R side. A rack bush is not disposed at the second end 12R of the rack shaft 6R.

  In the constituent elements of the present embodiment, the same constituent elements as those of the embodiment of FIG. 11 are denoted by the same reference numerals as those of the constituent elements of the embodiment of FIG. According to this reference embodiment, the urging force F3 by the first rack bush 16R has the rack shaft 6 as the second pinion 9 with the position P2 holding the rack shaft 6 between the first pinion 7R and the first rack guide 39 as a fulcrum. A moment M3 in the direction of pressing is generated.

  On the other hand, the urging force F4 by the second rack bush 17R generates a moment M4 in a direction in which the rack shaft 6 is separated from the second pinion 9 with the position P2 as a fulcrum. However, the second rack bush 17R is disposed between the pinion shafts 8R and 10, and is relatively close to the position P2 serving as a fulcrum (for example, compared with the case where the rack bush is disposed at the second end 12R). The moment M4 can be made relatively small. Therefore, an increase in backlash between the second pinion 9 and the second rack 5 can be suppressed.

  The present invention is not limited to the above-described embodiment, and each elastic convex portion may be formed in a cross-sectional mountain shape. In addition, various modifications can be made within the scope of the claims of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Steering device, 2 ... Steering mechanism, 3 ... 1st housing, 4 ... 1st rack, 5 ... 2nd rack, 6 ... Rack shaft, 7 ... 1st pinion, 8 ... 1st pinion shaft, 9 ... 1st 2 pinion, 10 ... 2nd pinion shaft, 11 ... first end of (rack shaft), 12 ... second end of (rack shaft), 16 ... first rack bush, 17 ... second rack bush, 18 ... Steering member, 19 ... steering shaft, 20,22 ... universal joint, 21 ... intermediate shaft, 23 ... steering assist mechanism, 24 ... electric motor, 25 ... deceleration mechanism, 29 ... drive gear, 30 ... driven gear, 33 ... second Housing, 39 ... 1st rack guide, 49 ... 2nd rack guide, C1 ... center axis of (first pinion shaft), C2 ... center axis of (second pinion shaft), CR ... center axis of (rack axis), PP ... includes the central axis of the latic axis and 1 pinion shaft center axis parallel to the plane of, (rack shaft) X1 ... axial direction

Claims (3)

The first rack has a first end and a second end that are inserted through the housing and are axially opposed. The first rack and the second of the two ends are relatively close to the first end. A rack shaft having a second rack relatively close to the end on the same side with respect to the central axis;
A first pinion shaft having a first pinion meshing with the first rack;
A second pinion that meshes with the second rack, and is disposed on the same side as the first pinion shaft with respect to a plane that includes the central axis of the rack shaft and is parallel to the central axis of the first pinion shaft; A second pinion shaft;
A first rack guide held by the housing and biasing the rack shaft from the back of the first rack toward the first pinion;
A second rack guide held by the housing and biasing the rack shaft toward the second pinion from the back of the second rack;
A first rack bush supported by the housing, slidably supporting a first end of the rack shaft in an axial direction, and biasing the rack shaft toward the first pinion;
A second rack bush supported by the housing, slidably supporting a first end of the rack shaft in an axial direction, and biasing the rack shaft toward the first pinion and the second pinion; A steering apparatus comprising:   2. The steering device according to claim 1, wherein the second rack bush is disposed between the first pinion shaft and the second pinion shaft with respect to an axial direction of the rack shaft. In Claim 1 or 2, the first pinion shaft is for transmitting a steering assist force,
The second pinion shaft is for manual steering force transmission,
A steering device in which only the first rack bush and the second rack bush are provided as bearings for supporting the rack shaft.

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