JP7506623B2 - Steering system - Google Patents

Description

The present invention relates to a steering device.

One example of a conventional steering device is described in Patent Document 1 below.

This steering device changes the direction of the steered wheels by converting the rotation of the steering wheel into axial movement of the rack shaft via a rack-and-pinion mechanism having a pinion shaft and rack shaft that mesh with each other, pushing and pulling the vehicle's knuckles. That is, the steering device is equipped with a pinion shaft as a steering shaft linked to the steering wheel, and a rack shaft whose both axial ends are linked to the steered wheels and mesh with the pinion shaft. In addition, in this steering device, the proper meshing between the pinion shaft and the rack shaft is maintained by a biasing mechanism that biases the back surface of the rack shaft toward the pinion shaft.

Specifically, the biasing mechanism includes a retainer member that supports the back surface of the rack shaft, a biasing member that biases the retainer member, an adjustment member that adjusts the biasing force (preload) of the biasing member, and an annular seal member that is disposed on the outer periphery of the base end of the retainer member and is interposed between the retainer member and the housing to keep the inside of the housing liquid-tight. In other words, this biasing mechanism maintains proper meshing between the pinion shaft and the rack shaft by applying the biasing force of the biasing member, adjusted based on the amount of screwing of the adjustment member, to the rack shaft via the retainer member.

JP 2014-185933 A

However, with the conventional steering device, when the rack shaft is displaced in the vertical direction due to an external input input via the steered wheels, the retainer member that supports the rack shaft by embracing its back surface is also displaced in accordance with the displacement of the rack shaft. As a result, there is a risk that the retainer member that supports the upper and lower ends of the rack shaft, particularly the pair of protruding parts, may come into contact with the housing, causing a striking sound, and there is still room for improvement.

In particular, because the seal member is disposed on the outer periphery of the base end of the retainer member, when the external input occurs, the retainer member is displaced so as to swing up and down around the seal member as a fulcrum. This may cause the pair of protrusions of the retainer member to come into strong contact with the inner surface of the housing.

The present invention was devised in consideration of the technical problems with the conventional steering devices, and aims to provide a steering device that can suppress the generation of striking noise caused by contact between the retainer member and the housing.

In one aspect, the present invention includes a first elastic member that surrounds the outer circumferential surface of the first end of the retainer body.

This invention makes it possible to suppress the generation of impact noise caused by contact between the retainer member and the housing.

1 is a schematic diagram of a steering device according to the present invention. FIG. 2 is a vertical sectional view of the rack support mechanism shown in FIG. 1 according to the first embodiment of the present invention. 3A is a vertical cross-sectional view of the retainer member shown in FIG. 2, and FIG. 3B is an enlarged view of part A in FIG. 3A is an enlarged view of a main portion of FIG. 2, and FIG. 3B is an enlarged view of a portion B of FIG. 5A is a vertical cross-sectional view of a retainer member in a state in which first and second elastic members are in a free state, and FIG. 5B is an enlarged view of a portion C in FIG. 5A. 6A is an enlarged cross-sectional view of a main portion of a rack support mechanism formed by incorporating the retainer member shown in FIG. 5 into a housing, and FIG. 6B is an enlarged view of a portion D in FIG. 13A is a perspective view of a retainer member showing a free state of a first elastic member according to a third embodiment of the present invention, and FIG. 13B is a vertical sectional view of the retainer member shown in FIG. 8 is an enlarged cross-sectional view of a main portion of a rack support mechanism formed by incorporating the retainer member shown in FIG. 7 into a housing. FIG. 13 is a vertical cross-sectional view of the retainer member according to the fourth embodiment of the present invention, in which the first elastic member is in a free state. FIG. 11 is a vertical cross-sectional view of a rack support mechanism in a conventional steering device.

The following describes in detail an embodiment of a steering device according to the present invention with reference to the drawings.

(Configuration of the steering device)
FIG. 1 is a schematic diagram of a steering device according to the present invention, showing the structure of the steering device.

As shown in FIG. 1, the steering device includes an input shaft 1 connected to a steering wheel SW, a pinion shaft 2 connected to the input shaft 1 via a torsion bar (not shown) for relative rotation and having a pinion gear 2a at its tip, and a rack shaft 3 having a rack gear 3a that meshes with the pinion gear 2a formed in a predetermined axial range on the front side, and both ends of which are connected to the left and right steered wheels WL and WR of the vehicle.

In other words, in the steering device, when the steering wheel SW rotates, the input shaft 1 rotates and the torsion bar (not shown) is twisted, and the pinion shaft 2 rotates following the input shaft 1 due to the elastic force of the torsion bar generated by the torsional deformation of the torsion bar. Then, the rotational motion of the pinion shaft 2 is converted into the linear motion of the rack shaft 3 by a rack-pinion mechanism formed by the meshing of the pinion gear 2a and the rack gear 3a, and the rack shaft 3 moves axially in the left-right direction of the vehicle, changing the orientation of both steered wheels WL, WR.

In addition, in the steering device, a torque sensor TS is disposed at the connection between the input shaft 1 and the pinion shaft 2 via the torsion bar (not shown). This torque sensor TS detects the steering torque with which the driver operates the steering wheel SW based on the relative rotation amount between the input shaft 1 and the pinion shaft 2, i.e., the torsion amount of the torsion bar (not shown). Then, a steering assist torque is applied to the pinion shaft 2 via the reduction mechanism 4 from the electric motor M, which is controlled based on the detection result of this steering torque, to assist the driver's steering. In this embodiment, a so-called worm gear mechanism is used as the reduction mechanism 4.

[First embodiment]
2 to 4 show a first embodiment of a steering device according to the present invention. For ease of explanation, the following description will refer to the direction along the central axis Y in Fig. 2 to 4 as the "axial direction", the direction perpendicular to the central axis Y as the "radial direction", and the direction around the central axis Y as the "circumferential direction".

(Configuration of rack support mechanism)
FIG. 2 shows a vertical cross-sectional view of the rack support mechanism shown in FIG. 1. FIG. 3(a) shows a vertical cross-sectional view of the retainer member shown in FIG. 2, and FIG. 3(b) shows an enlarged view of part A in FIG. 3(a). FIG. 4(a) shows an enlarged view of the main part of FIG. 2, and FIG. 4(b) shows an enlarged view of part B in FIG. 2(a). In the following, for convenience of explanation, the left side in FIG. 2 to FIG. 4 is defined as "front" and the right side in FIG. 4 is defined as "rear". In addition, for convenience of explanation, the end of the retainer member 61 on the rack shaft 3 side in the axial direction is defined as "first end" and the end on the opposite side to the rack shaft 3 (the end on the coil spring 62 side) is defined as "second end".

As shown in FIG. 2, the steering device has a rack shaft 3 housed in a rack housing 51 of a housing 5 that is provided on the lower side of the steering device along the left-right direction (X-axis direction) of the vehicle, and a pinion shaft 2 housed in a pinion housing 52 that is provided on the housing 5 along the Z-axis direction facing the front side of the rack shaft 3 and intersecting with the rack housing 51.

The steering device is also provided with a rack support mechanism 6 on the rear side of the rack shaft 3, which supports the rack shaft 3 so as to maintain proper meshing between the pinion shaft 2 and the rack shaft 3. The rack support mechanism 6 has a retainer member 61 housed in the front end of a retainer housing 53, which is provided facing the rear side 3b of the rack shaft 3 along the Y-axis direction so as to be perpendicular to the rack housing 51, a coil spring 62 as a biasing member that biases the retainer member 61 toward the rack shaft 3, and an adjustment screw 63 as an adjustment member that is screwed into an opening on the rear end side of the retainer housing 53 and serves to adjust the biasing force of the coil spring 62.

As shown in Figs. 2 to 4, the retainer member 61 is made of a predetermined metal material and is generally cylindrically shaped, and is accommodated in the retainer accommodating portion 53 with a small gap C between it and the cylindrical inner peripheral surface 53a so that it can slide along the Y-axis direction. Specifically, the retainer member 61 has a generally cylindrical retainer body portion 611 having a cylindrical outer peripheral surface 611a that is generally circular in cross section, a rack support surface 612 that is provided at the first axial end portion and supports the back surface 3b of the rack shaft 3, and a concave first spring receiving portion 613 that is formed at the second axial end portion and receives the front end portion of the coil spring 62 on the inner peripheral side.

The retainer body 611 has a cylindrical general portion 614 that faces the cylindrical inner peripheral surface 53a of the retainer housing 53 with a small gap C between them, and a pair of protrusions 615 that are formed symmetrically on the first end side of the general portion 614 with respect to the central axis Y and form a rack support surface 612 on the inner peripheral side. That is, the retainer body 611 has a pair of protrusions 615 that are symmetrical on both sides of the central axis Y by cutting out the end surface on the first end side of the cylindrical general portion 614 in an arc shape corresponding to the back surface 3b of the rack shaft 3 along the X-axis direction in FIG. 2, and a concave arc-shaped rack support surface 612 is formed on the inner peripheral side of the pair of protrusions 615.

The rack support surface 612 is formed along the X-axis direction at the first end of the retainer body 611, and has a concave arc surface corresponding to the back surface 3b of the rack shaft 3. A friction reducing member 64 made of a fluororesin material, which is a low-friction material, is provided on the surface of the rack support surface 612 so as to cover the entire rack support surface 612. The friction reducing member 64 is made by curving a thin plate made of the low-friction material, and is attached and fixed to the rack support surface 612 by engaging an engagement protrusion 640 formed on the center of the inner side facing the rack support surface 612 with an engagement hole 612a formed in the center of the rack support surface 612.

A first elastic member 65 made of a predetermined elastic material, such as rubber, is provided on the outer periphery of the first end of the retainer member 61. That is, on the outer periphery of the first end of the retainer body 611, i.e., on the outer periphery of the pair of protruding portions 615, a first elastic member mounting portion 616 having an outer diameter reduced in a stepped manner compared to the general portion 614 is cut out with a certain width along the circumferential direction, and the first elastic member 65 is attached to the first elastic member mounting portion 616 by vulcanization adhesion.

The first elastic member 65 is disposed flush with the outer peripheral edge of the rack support surface 612 so that its front end face (the end face on the first end side) faces the tip of the retainer main body 611, and its rear end face (the end face on the second end side) is in close contact with the step portion 616a of the first elastic member mounting portion 616, with its inner peripheral surface of a constant inner diameter bonded to the outer peripheral surface of the first elastic member mounting portion 616.

More specifically, the first elastic member 65 has a large diameter portion 651 having an outer diameter R1 larger than the outer diameter R0 of the general portion 614 of the retainer body 611, and a small diameter portion 652 that is disposed closer to the general portion 614 than the large diameter portion 651 and has an outer diameter R2 smaller than the outer diameter R0 of the general portion 614. Note that the large diameter portion 651 and the small diameter portion 652 are formed in a stepped shape as described above, but the large diameter portion 651 and the small diameter portion 652 are smoothly connected by the R portion 653, thereby suppressing the occurrence of stress concentration when the first elastic member 65 is compressed.

The large diameter portion 651 extends over most of the axial region of the first end of the first elastic member 65, and is compressed when the retainer member 61 is inserted (housed) in the retainer housing portion 53, making it possible for the large diameter portion 651 to elastically contact the cylindrical inner circumferential surface 53a. In other words, the large diameter portion 651 is constantly in elastic contact with the cylindrical inner circumferential surface 53a of the retainer housing portion 53, making it possible for the large diameter portion 651 to absorb the rocking displacement of the retainer member 61 caused by an external input.

The small diameter portion 652 is provided in an axial region adjacent to the step portion 616a of the first elastic member mounting portion 616, which is closer to the second end than the large diameter portion 651, and functions as a so-called escape groove that prevents the bulging deformation portion 651a, which is compressed and bulges toward the step portion 616a of the first elastic member mounting portion 616, from contacting the step portion 616a when the retainer member 61 is inserted (housed) in the retainer housing portion 53. In other words, the outer diameter and axial region of the small diameter portion 652 are set so as to be able to avoid contact between the bulging deformation portion 651a, which occurs due to the compressive deformation of the large diameter portion 651, and the step portion 616a of the first elastic member mounting portion 616.

The coil spring 62 is a well-known coil spring with a constant inner and outer diameter in the axial direction, and its front end is seated on the bottom surface 613a of the first spring receiving portion 613 provided at the rear end (second end) of the retainer main body portion 611, and its rear end is seated on the bottom surface 633a of the second spring receiving portion 633 provided at the front end of the adjusting screw 63, so that it is interposed between the retainer member 61 and the adjusting screw 63 with a predetermined preload.

The adjusting screw 63 is provided at the front end side and has a bottomed cylindrical spring holding portion 631 that holds the coil spring 62, and a male threaded portion 632 that is screwed into a female threaded portion 53b formed on the inner peripheral surface of the rear end side opening of the retainer housing portion 53. The spring holding portion 631 has an outer diameter slightly smaller than the female threaded portion 53b, and is formed with a stepped diameter reduction relative to the male threaded portion 632, and a second spring receiving portion 633 that receives the rear end of the coil spring 62 is formed on the inner peripheral side. The male threaded portion 632 has a tool engagement groove 632a that opens to the outside, and is screwed into the female threaded portion 53b of the retainer housing portion 53 via a tool (not shown) that engages with the tool engagement groove 632a. In addition, the male threaded portion 632 is provided so that its rear end protrudes outward from the opening of the retainer housing portion 53, and is fixed to the rear end of the retainer housing portion 53 in a non-loosening state by a lock nut 66 that is screwed onto the male threaded portion 632 protruding from this opening.

A continuous annular seal groove 53c is formed in the circumferential direction at the rear end of the retainer housing 53 adjacent to the female threaded portion 53b, with a stepped diameter. A rubber annular seal member 67, typically an O-ring, is fitted into this seal groove 53c. In other words, the inside of the retainer housing 53 is kept liquid-tight by the annular seal member 67 elastically abutting against the bottom surface of the seal groove 53c and the outer periphery of the spring holding portion 631 of the adjusting screw 63.

(Effects of this embodiment)
FIG. 10 shows a vertical cross-sectional view of a rack support mechanism 6 of a conventional steering device.

As shown in Figure 10, in a conventional steering device, when the rack shaft 3 is displaced upward by an external input Fo input from the road surface via the steered wheels, the retainer member 61, which supports the back surface 3b of the rack shaft 3 by clamping it from above and below, is subjected to pressing forces F1, F2 that press the retainer member 61 upward at the end portion on the rack shaft 3 side (first end portion) and the end portion on the opposite side to the rack shaft 3 side (second end portion), and moments M1, M2 that act in the rotational direction with an O-ring 60 provided on the outer periphery of the retainer member 61 as a fulcrum act on the retainer member 61. Thus, in conventional steering devices, a resultant force Ft1 (= F1 + M1) acts on the first end of the retainer member 61, and a resultant force Ft2 (= F2 - M2) acts on the second end of the retainer member 61. This causes the pair of protrusions 615 to come into relatively strong contact with the housing 5 (the cylindrical inner surface 53a of the retainer housing portion 53) based on the resultant force Ft1, which is the largest of the resultant forces Ft1 and Ft2, and there is a risk of generating a hitting sound, so there is still room for improvement.

In contrast, the steering device according to this embodiment provides the following effects, thereby solving the technical problems of the conventional steering devices.

The steering device is a steering device that transmits steering force to the steered wheels WL and WR, and includes a pinion shaft 2 that is connected to the steering wheel SW, a rack shaft 3 that meshes with the pinion shaft 2 and converts the rotational force of the pinion shaft 2 into an axial moving force and transmits it to the steered wheels WL and WR, a rack accommodating section 51 that accommodates at least a portion of the rack shaft 3, and a retainer accommodating section 53 that is provided to face the rack accommodating section 51 at the position where the pinion shaft 2 and the rack shaft 3 mesh, and a biasing member that is disposed in the retainer accommodating section 53 and exerts a biasing force toward the back surface of the rack shaft 3. The retainer member 61 includes a coil spring 62, a cylindrical retainer body 611 having a first end that abuts and supports the back surface of the rack shaft 3 and a second end that abuts the coil spring 62 located opposite the rack shaft 3, a rack support surface 612 that is provided at the first end of the retainer body 611, is curvedly recessed along the back surface of the rack shaft 3, and supports the back surface of the rack shaft 3, and a first elastic member 65 that surrounds the outer circumferential surface of the first end side of the retainer body 611.

In this manner, in this embodiment, the first elastic member 65 is provided on the outer periphery of the first end of the retainer member 61 that supports the back surface 3b of the rack shaft 3. This makes it possible to actively abut the first elastic member 65, rather than the retainer main body 611, against the housing 5 (cylindrical inner periphery 53a of the retainer accommodating portion 53) when the rack shaft 3 moves upward due to an external input Fo (see FIG. 2). This allows the first elastic member 65 to absorb the displacement of the retainer member 61 that accompanies the upward movement of the rack shaft 3, and makes it possible to suppress the generation of hitting sounds caused by the retainer main body 611 abutting against the housing.

In addition, in this embodiment, even if the first elastic member 65 is worn down due to the retainer member 61 coming into contact with the housing 5, the first elastic member 65 is made of an elastic material, so even if the first elastic member 65 wears down and generates wear powder, the retainer member 61 can be prevented from sticking due to the wear powder.

In addition, even if the outer diameter R1 of the first elastic member 65 is the same as the outer diameter R0 of the general portion 614 of the retainer body 611, the elastic effect of the first elastic member 65 (the effect of cushioning or absorbing the abutment with the cylindrical inner circumferential surface 53a of the retainer housing 53) can be obtained, but in this embodiment, the outer diameter R1 of the first elastic member 65 is set to be larger than the outer diameter R0 of the general portion 614 of the retainer body 611. This allows the thickness of the first elastic member 65 to be increased, improving the elastic effect of the first elastic member 65 and more effectively suppressing the generation of hitting sounds caused by the abutment between the first end side of the retainer body 611 and the housing 5 (cylindrical inner circumferential surface 53a of the retainer housing 53).

Furthermore, in this embodiment, the retainer main body 611 has a general portion 614 in which the first elastic member 65 is not disposed, and a first elastic member attachment portion 616 which is formed with a stepped diameter reduction on the first end side of the general portion 614 relative to the general portion 614 and has the first elastic member 65 attached to its outer periphery, and the first elastic member 65 has a large diameter portion 651 having an outer diameter larger than the general portion 614, and a small diameter portion 652 which is disposed on the general portion 614 side of the large diameter portion 651 and has an outer diameter smaller than the general portion 614.

As described above, in this embodiment, the first elastic member 65 has a small diameter portion 652 that is smaller in diameter than the general portion 614 in the axial region on the general portion 614 side, i.e., in the axial region adjacent to the step portion 616a formed between the general portion 614 and the first elastic member mounting portion 616. Therefore, when the first elastic member 65 is in a compressed state, it is possible to suppress problems such as the retainer main body portion 611 being pressed against the step portion 616a of the first elastic member mounting portion 616, and the first elastic member 65 being sandwiched between the general portion 614 and the cylindrical inner circumferential surface 53a of the retainer housing portion 53 (small gap C).

[Second embodiment]
5 and 6 show a second embodiment of a steering device according to the present invention, in which the configuration of the retainer member 61 in the rack support mechanism 6 according to the first embodiment is changed. Note that the basic configuration other than the above changes is the same as that of the first embodiment, and therefore the same components as those in the first embodiment are denoted by the same reference numerals and description thereof will be omitted.

Figure 5 shows a second embodiment of the present invention, where (a) is a vertical cross-sectional view of the retainer member 61 in the free state of the first elastic member 65 and the second elastic member 68, and (b) is an enlarged view of part C in (a) of the same figure. Also, Figure 6 (a) is an enlarged cross-sectional view of a main part of the rack support mechanism 6 formed by incorporating the retainer member 61 shown in Figure 5 into the housing 5, and (b) is an enlarged view of part D in (a) of the same figure.

As shown in Figures 5 and 6, in the steering device according to this embodiment, a second elastic member 68 made of an elastic material similar to the first elastic member 65, such as a rubber material, is provided on the outer periphery of the second end of the retainer member 61. That is, on the outer periphery of the second end of the retainer body 611, a second elastic member mounting portion 617 having an outer diameter reduced in a stepped manner compared to the general portion 614 is cut out with a certain width along the circumferential direction, and the second elastic member 68 is attached to the second elastic member mounting portion 617 by vulcanization adhesion.

The second elastic member 68 is arranged so that its rear end face (the end face on the second end side) faces the rear end side of the retainer main body 611, and its front end face (the end face on the first end side) is in close contact with the step portion 617a of the second elastic member mounting portion 617, with its inner circumferential surface of a constant inner diameter being bonded to the outer circumferential surface of the second elastic member mounting portion 617.

More specifically, the second elastic member 68 has a large diameter portion 681 having an outer diameter R1 larger than the outer diameter R0 of the general portion 614 of the retainer body 611, and a small diameter portion 682 that is disposed closer to the general portion 614 than the large diameter portion 681 and has an outer diameter R2 smaller than the outer diameter R0 of the general portion 614. Note that the large diameter portion 681 and the small diameter portion 682 are formed in a stepped shape as described above, but the large diameter portion 681 and the small diameter portion 682 are smoothly connected by the R portion 683, thereby suppressing the occurrence of stress concentration when the second elastic member 68 is compressed.

The large diameter portion 681 extends over most of the axial region of the second end of the second elastic member 68, and is compressed when the retainer member 61 is inserted (housed) in the retainer housing portion 53, making it possible for the large diameter portion 681 to elastically contact the cylindrical inner circumferential surface 53a. In other words, the large diameter portion 681 is constantly in elastic contact with the cylindrical inner circumferential surface 53a of the retainer housing portion 53, making it possible for the large diameter portion 681 to absorb the rocking displacement of the retainer member 61 caused by an external input.

The first elastic member 65 is disposed so that the front end of the first elastic member 65 and the front end of the retainer member 61 are generally flush with each other, whereas the second elastic member 68 is disposed offset inward from the rear end of the retainer member 61. That is, the axial width L1 of the second elastic member 68 is set smaller than the axial width L2 of the second elastic member mounting portion 617, and the rear end of the second elastic member 68 and the rear end of the retainer member 61 are spaced apart by a predetermined distance D. The distance D between the rear end of the second elastic member 68 and the rear end of the retainer member 61 is set to a distance that makes it possible to avoid contact between the expanding deformation portion 681a, which occurs due to the compressive deformation of the large diameter portion 681, and the adjusting screw 63.

The small diameter portion 682 is provided in an axial region adjacent to the step portion 617a of the second elastic member mounting portion 617, which is closer to the first end than the large diameter portion 681, and functions as a so-called escape groove that prevents the bulging deformation portion 681a, which is compressed and bulges toward the step portion 617a of the second elastic member mounting portion 617, from contacting the step portion 617a when the retainer member 61 is inserted (housed) in the retainer housing portion 53. In other words, the outer diameter and axial region of the small diameter portion 682 are set so as to be able to avoid contact between the bulging deformation portion 681a, which occurs due to the compressive deformation of the large diameter portion 681, and the step portion 617a of the second elastic member mounting portion 617.

As described above, in the steering device according to this embodiment, the retainer member 61 has a second elastic member that surrounds the outer peripheral surface of the second end side of the retainer body portion 611.

When the retainer member 61 is displaced upward by the external input Fo, a pressing force F2 is also applied to the second end side of the retainer member 61. Therefore, the pressing force F2 causes at least a small amount of the second end side of the retainer main body 611 to come into contact with the housing 5 (the cylindrical inner surface 53a of the retainer accommodating portion 53).

Therefore, as in this embodiment, a second elastic member 68, which is an elastic member similar to that on the first end side, is provided on the second end side of the retainer main body 611, thereby making it possible to suppress the generation of impact sounds that accompany contact between the second end side of the retainer main body 611 and the housing 5 (cylindrical inner surface 53a of the retainer accommodating portion 53).

In this embodiment, the retainer body 611 has a general portion 614 provided in the middle between the first end and the second end, where the first elastic member 65 and the second elastic member 68 are not arranged, a first elastic member mounting portion 616 formed in a stepped shape with a reduced diameter on the first end side from the general portion 614 and on the outer periphery side of the first elastic member 65, and a second elastic member mounting portion 617 formed in a stepped shape with a reduced diameter on the second end side from the general portion 614 and on the outer periphery side of the second elastic member 68. In the free state of the first elastic member 65 and the second elastic member 68, the outer diameter R1 of the first elastic member 65 mounted on the first elastic member mounting portion 616 and the outer diameter R1 of the second elastic member 68 mounted on the second elastic member mounting portion 617 are set to be larger than the outer diameter R0 of the general portion 614.

In this way, the outer diameter R1 of the first and second elastic members 65, 68 is set larger than the outer diameter R0 of the general portion 614 of the retainer body 611, so that the thickness of the first and second elastic members 65, 68 can be increased. This improves the elastic effect of the first and second elastic members 65, 68, and more effectively suppresses the generation of hitting sounds that accompany the contact between the second end side of the retainer body 611 and the housing 5 (cylindrical inner peripheral surface 53a of the retainer accommodating portion 53).

In addition, in this embodiment, an adjustment screw 63, which is a screw-shaped adjustment member used to adjust the biasing force of the coil spring 62, is provided on the second end side of the retainer member 61, and the retainer member 61 has a second elastic member 68 on a second elastic member mounting portion 617 provided on the second end side of the retainer main body 611, and the axial width of the second elastic member 68 is smaller than the axial width of the second elastic member mounting portion 617.

If the axial width of the second elastic member 68 is the same as or greater than the axial width of the second elastic member mounting portion 617, when the second elastic member 68 is compressed, the axially expanding and deforming portion may become pinched between the retainer member 61 and the adjusting screw 63.

Therefore, in this embodiment, the axial width L1 of the second elastic member 68 is set smaller than the axial width L2 of the second elastic member mounting portion 617, thereby preventing damage to the second elastic member 68 caused by the second elastic member 68 being pinched between the retainer member 61 and the adjusting screw 63 in the compressed state.

[Third embodiment]
7 and 8 show a third embodiment of a steering device according to the present invention, in which the configuration of the retainer member 61 in the rack support mechanism 6 according to the first embodiment is modified. Note that the basic configuration other than the above modifications is the same as that of the first embodiment, and therefore the same components as those in the first embodiment are denoted by the same reference numerals and description thereof will be omitted.

Figure 7 shows a third embodiment of the present invention, where (a) is a perspective view of the retainer member 61 in the free state of the first elastic member 65, and (b) is a longitudinal cross-sectional view of the retainer member 61 in the free state. Also, Figure 8 shows an enlarged cross-sectional view of a main part of the rack support mechanism 6 formed by incorporating the retainer member 61 shown in Figure 7 into the housing 5.

As shown in Figures 7 and 8, in the steering device according to this embodiment, the cylindrical outer circumferential surface 611a of the retainer body 611 is formed flat over the entire axial length, and a first elastic member 65 having a generally uniform thickness is attached by vulcanization adhesion to the entire outer circumferential side of the cylindrical outer circumferential surface 611a. That is, the first elastic member 65 extends over the entire axial length of the general portion 614 so that its front end is flush with the end face of the first end of the retainer body 611 and its rear end is flush with the end face of the second end of the retainer body 611.

As described above, in the steering device according to this embodiment, the first elastic member 65 is provided on the entire outer circumferential surface (cylindrical outer circumferential surface 611a) of the retainer body 611.

In this way, since the first elastic member 65 is provided on the entire outer peripheral surface (cylindrical outer peripheral surface 611a) of the retainer main body 611, there is no need to form (machine) the first elastic member attachment portion 616 on a portion of the outer peripheral side of the retainer main body 611 as in the first embodiment, and the shape (outer shape) of the retainer main body 611 can be simplified. This makes it possible to improve the productivity of the retainer member 61 and reduce manufacturing costs.

[Fourth embodiment]
9 shows a fourth embodiment of a steering device according to the present invention, in which the configuration of the first elastic member 65 in the rack support mechanism 6 according to the third embodiment is changed. Note that the basic configuration other than the above changes is the same as that of the third embodiment, and therefore the same components as those in the third embodiment are denoted by the same reference numerals and description thereof will be omitted.

Figure 9 shows a fourth embodiment of the present invention, and is a vertical cross-sectional view of the retainer member 61 in the free state of the first elastic member 65. Note that the vertical cross-section of the rack support mechanism 6 formed by incorporating the retainer member 61 shown in Figure 9 into the housing 5 is the same as that shown in Figure 8, so Figure 8 should be referred to as appropriate for the assembled state of the retainer member 61.

As shown in FIG. 9, the steering device according to this embodiment is formed so that the outer diameter of the first elastic member 65, which extends over the entire axial area of the cylindrical outer circumferential surface 611a of the retainer body 611, increases from the first end side to the second end side of the retainer body 611. That is, the first elastic member 65 according to this embodiment has a constant inner diameter on the inner circumferential side in the axial direction, and is formed in a conical taper shape in which the thickness gradually increases from the first end side to the second end side of the retainer body 611.

As described above, in the steering device according to this embodiment, the outer periphery of the first elastic member 65 is formed in a tapered shape such that the outer diameter of the first elastic member 65 gradually increases from the first end side toward the second end side.

In this manner, in this embodiment, the outer periphery of the first elastic member 65 is tapered so that the diameter gradually increases toward the second end in the axial direction, and the tip side that is inserted into the retainer housing portion 53 is tapered. This improves the ease of inserting the retainer member 61 into the retainer housing portion 53.

In addition, because the outer periphery of the first elastic member 65 is tapered so that the diameter increases toward the second end, when the first end of the retainer member 61 is displaced upward by an external input Fo, the elastic force of the first elastic member 65 can be applied generally evenly to the cylindrical inner periphery 53a of the retainer accommodating portion 53. This improves the retention of the retainer member 61 by the first elastic member 65.

The present invention is not limited to the configurations and aspects exemplified in the above embodiment, and can be freely modified according to the specifications and costs of the target application as long as the above-mentioned effects of the present invention can be achieved.

In particular, in the first and second embodiments, the outer diameter of the first and second elastic members 65, 68 is set to be larger than the outer diameter of the general portion 614 of the retainer body 611. However, the present invention is not limited to the configurations of the first and second embodiments. The outer diameter of the first and second elastic members 65, 68 may be the same as the outer diameter of the general portion 614 of the retainer body 611, or the outer diameter of the first and second elastic members 65, 68 may be slightly smaller than the outer diameter of the general portion 614 of the retainer body 611 to the extent that the general portion 614 does not abut against the cylindrical inner peripheral surface 53a of the retainer housing portion 53 when the retainer member 61 is displaced upward when an external input is applied to the rack shaft 3.

As a steering device based on the above-described embodiment, the following configurations are possible.

That is, in one aspect, the steering device is a steering device that transmits steering force to steered wheels, and includes a housing having a pinion shaft that is linked to a steering wheel, a rack shaft that meshes with the pinion shaft and converts the rotational force of the pinion shaft into an axial moving force and transmits it to the steered wheels, a rack accommodating section that accommodates at least a portion of the rack shaft, and a retainer accommodating section that is provided so as to face the rack accommodating section at a position where the pinion shaft and the rack shaft mesh, and a retainer that is disposed in the retainer accommodating section and faces the back surface of the rack shaft. The retainer member is pressed against the back surface of the rack shaft based on the biasing force of the biasing member, and is a cylindrical retainer body having a first end that abuts and supports the back surface of the rack shaft and a second end that abuts against the biasing member located opposite the rack shaft, a rack support surface that is provided at the first end of the retainer body, is recessed in a curved shape along the back surface of the rack shaft, and supports the back surface of the rack shaft, and a first elastic member that surrounds the outer circumferential surface of the first end side of the retainer body.

In a preferred embodiment of the steering device, the retainer member has a second elastic member that surrounds the outer circumferential surface of the second end side of the retainer body.

In another preferred embodiment, in any of the steering device embodiments, the retainer body has a general portion provided in the middle between the first end and the second end, where the first elastic member and the second elastic member are not disposed, a first elastic member mounting portion formed to have a stepped diameter smaller than the general portion on the first end side than the general portion and to which the first elastic member is attached on the outer periphery, and a second elastic member mounting portion formed to have a stepped diameter smaller than the general portion on the second end side than the general portion and to which the second elastic member is attached on the outer periphery, and in the free state of the first elastic member and the second elastic member, the outer diameter of the first elastic member attached to the first elastic member mounting portion and the outer diameter of the second elastic member attached to the second elastic member mounting portion are set to be larger than the outer diameter of the general portion.

In yet another preferred embodiment, in any of the steering device embodiments, a screw-shaped adjustment member for adjusting the biasing force of the biasing member is provided on the second end side of the retainer member, the retainer member has the second elastic member at a second elastic member mounting portion provided on the second end side of the retainer body, and the axial width of the second elastic member is smaller than the axial width of the second elastic member mounting portion.

In yet another preferred embodiment, in any of the steering device embodiments, the first elastic member is provided on the entire outer circumferential surface of the retainer body.

In yet another preferred embodiment, in any of the steering device embodiments, the outer periphery of the first elastic member is formed in a tapered shape such that the outer diameter of the first elastic member gradually increases from the first end side toward the second end side.

In yet another preferred embodiment, in any of the steering device embodiments, the retainer body has a general portion where the first elastic member is not disposed, and a first elastic member mounting portion that is formed with a stepped diameter reduction on the first end side of the general portion relative to the general portion and has the first elastic member mounted on the outer periphery, and the first elastic member has a large diameter portion with an outer diameter larger than the general portion, and a small diameter portion that is disposed on the general portion side of the large diameter portion and has an outer diameter smaller than the general portion.

2... pinion shaft, 3... rack shaft, 5... housing, 51... rack housing, 53... retainer housing, 61... retainer member, 611... retainer body, 612... rack support surface, 614... general part, 615... protrusion, 616... first elastic member mounting part, 617... second elastic member mounting part, 62... coil spring (biasing member), 63... adjust screw (adjustment member), 65... first elastic member, 68... second elastic member, SW... steering wheel, WL, WR... steered wheels,

Claims (7)

A steering device that transmits steering force to steered wheels,
A pinion shaft that is linked to a steering wheel;
a rack shaft that meshes with the pinion shaft, converts a rotational force of the pinion shaft into an axial moving force and transmits the same to the steered wheels;
a housing including a rack accommodating portion that accommodates at least a portion of the rack shaft, and a retainer accommodating portion provided to face the rack accommodating portion at a position where the pinion shaft and the rack shaft mesh with each other;
a biasing member that is disposed in the retainer receiving portion and that exerts a biasing force toward a back surface of the rack shaft;
a retainer member that is pressed against a back surface of the rack shaft based on the biasing force of the biasing member,
a cylindrical retainer body having a first end that abuts against and supports a back surface of the rack shaft and a second end that abuts against the biasing member located opposite the rack shaft;
a rack support surface provided at the first end of the retainer body, the rack support surface being curvedly recessed along a back surface of the rack shaft and supporting the back surface of the rack shaft;
a first elastic member attachment portion that is stepped in diameter at the first end portion of the retainer body and that opens in the axial direction at the first end portion;
a retainer member having
a first elastic member provided at the first elastic member attachment portion and surrounding an outer peripheral surface of the first end side of the retainer body portion;
A steering device comprising: 2. The steering device according to claim 1,
The steering device according to claim 1, wherein the retainer member has a second elastic member surrounding an outer circumferential surface of the second end side of the retainer body. 3. The steering device according to claim 2,
the retainer body portion is provided at an intermediate portion between the first end portion and the second end portion, and has a general portion in which the first elastic member and the second elastic member are not disposed, the first elastic member mounting portion is formed with a stepped diameter reduction on the first end side of the general portion relative to the general portion, and the first elastic member is mounted on an outer circumferential side of the general portion, and the second elastic member is mounted on an outer circumferential side of the general portion, and
A steering device characterized in that, in a free state of the first elastic member and the second elastic member, an outer diameter of the first elastic member attached to the first elastic member mounting portion and an outer diameter of the second elastic member attached to the second elastic member mounting portion are set to be larger than an outer diameter of the general portion. 3. The steering device according to claim 2,
A screw-shaped adjustment member for adjusting the biasing force of the biasing member is provided on the second end side of the retainer member,
the retainer member has the second elastic member at a second elastic member attachment portion provided on the second end side of the retainer body,
A steering device, wherein a width in the axial direction of the second elastic member is smaller than a width in the axial direction of the second elastic member mounting portion. 2. The steering device according to claim 1,
A steering device, wherein the first elastic member is provided on the entire outer circumferential surface of the retainer body. 6. The steering device according to claim 5,
A steering device characterized in that an outer circumferential side of the first elastic member is formed in a tapered shape such that an outer diameter of the first elastic member gradually increases from the first end side toward the second end side. 2. The steering device according to claim 1,
the retainer body portion has a general portion in which the first elastic member is not disposed, and the first elastic member attachment portion is formed in a stepped shape with a reduced diameter relative to the general portion on a side closer to the first end portion than the general portion, and the first elastic member is attached to an outer circumferential side of the first elastic member,
a first elastic member having an outer diameter larger than that of the first elastic member, and a small diameter portion disposed closer to the first elastic member than the first elastic member and having an outer diameter smaller than that of the first elastic member.

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