Rack guide device and steering device

Abstract

This rack guide device comprises: an accommodating wall portion having an interior space that extends in an orthogonal direction, a first opening that opens toward a rack bar, and a second opening that opens from the interior space in a direction opposite to the rack bar; an adjustment cover that closes the second opening; a pressure pad that comes into contact with the rack bar from the first opening; and a coil spring and an O-ring that are disposed between the adjustment cover and the pressure pad. One of the adjustment cover and the pressure pad has a facing surface that faces the other of the adjustment cover and the pressure pad. An annular groove is provided to the facing surface. The inner surface of the annular groove has an inner circumferential surface and an outer circumferential surface facing each other. The annular groove has a narrow groove for which the groove width between the inner circumferential surface and the outer circumferential surface is less than the line diameter of the O-ring before assembly, and a wide groove for which the groove width is greater than the line diameter of the O-ring before assembly.

Description

Technical Field

[0001] The present disclosure relates to a rack guide device and a steering device.

Background Art

[0002] As a type of steering device mounted on a vehicle, a rack & pinion system can be mentioned. Further, a rack & pinion type steering device includes a rack guide device that presses a rack bar toward a pinion in order to maintain the meshing between the rack bar and the pinion.

[0003] Describing the details of the rack guide device, the rack guide device includes a housing wall portion, an adjustment cover, a pressure pad, and a coil spring. The housing wall portion has an internal space extending in a direction orthogonal to the rack bar, a first opening opening from the internal space toward the rack bar, and a second opening opening in a direction opposite to the rack bar. The adjustment cover closes the second opening and forms the bottom wall of the internal space. The pressure pad is disposed in the internal space of the housing wall portion and abuts against the rack bar from the first opening portion. The coil spring is disposed between the pressure pad and the adjustment cover in a compressed state and applies a pressing force to the pressure pad.

[0004] Further, as shown in Patent Document 1 below, the adjustment cover has a facing surface facing the pressure pad. An annular groove is provided in the facing surface. And an O-ring is assembled in the annular groove. A part of the O-ring protrudes from the facing surface and abuts against the pressure pad. According to this, when the pressure pad moves toward the adjustment cover, the O-ring deforms, and the impact load input from the pressure pad to the adjustment cover is reduced.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0006] By the way, if there is a gap between the inner surface of the annular groove and the O-ring, the O-ring will escape into the gap due to the pressing from the pressure pad, making it easier for the pressure pad to contact the adjustment cover. For such reasons, an O-ring with a crush allowance is used, and the filling rate of the O-ring in the annular groove is increased.

[0007] On the other hand, when pressing an O-ring with a crush allowance into the annular groove, the air in the annular groove is blocked from escaping to the O-ring and is difficult to be discharged from the annular groove. Then, the air in the annular groove is gradually compressed by the O-ring and exerts a large counterforce against the pressing of the O-ring. From the above, a large load is required for pressing the O-ring, and the assembly of the O-ring is not easy.

[0008] The present disclosure has been made in view of the above problems, and an object thereof is to provide a rack guide device and a steering device that can easily assemble an O-ring into an annular groove.

MEANS FOR SOLVING THE PROBLEMS

[0009] To achieve the above object, a rack guide device according to one aspect of the present disclosure includes a housing wall portion having an internal space extending in a direction orthogonal to the rack bar, a first opening opening from the internal space toward the rack bar, and a second opening opening from the internal space in a direction opposite to the rack bar; an adjustment cover closing the second opening of the housing wall portion; a pressure pad disposed in the internal space and contacting the rack bar from the first opening; and a coil spring and an O-ring disposed between the adjustment cover and the pressure pad. One of the adjustment cover and the pressure pad has a facing surface facing the other of the adjustment cover and the pressure pad. An annular groove in which the O-ring is assembled is provided on the facing surface. The inner surface of the annular groove has an inner peripheral surface and an outer peripheral surface facing each other. The annular groove has a narrow-width groove in which the groove width between the inner peripheral surface and the outer peripheral surface is smaller than the wire diameter of the O-ring before assembly, and a wide-width groove in which the groove width is larger than the wire diameter of the O-ring before assembly.

[0010] The O-ring has a compression allowance with respect to the narrow-width groove. Therefore, the filling rate of the O-ring can be increased. Further, when the O-ring is pushed into the annular groove, a gap extending in the depth direction (hereinafter referred to as the depth-direction gap) is formed between the O-ring and the inner peripheral surface or between the O-ring and the outer peripheral surface in the wide-width groove. Therefore, the air in the annular groove is discharged, and the O-ring can be pushed in with a small force. From the above, it becomes easy to assemble the O-ring into the annular groove.

[0011] As one aspect of the above rack guide device, the outer peripheral surface has one or more outer peripheral arc surfaces extending in the circumferential direction with a predetermined diameter, and one or more outer peripheral bulging surfaces bulging radially outward of the outer peripheral arc surfaces. The inner peripheral surface has a constant diameter over the entire circumference. The narrow-width groove is disposed between the outer peripheral arc surface and the inner peripheral surface. The wide-width groove is disposed between the outer peripheral bulging surface and the inner peripheral surface.

[0012] As a desirable aspect of the above-described rack guide device, the opposing surface has a first annular surface disposed on the inner circumferential side of the annular groove and a second annular surface disposed on the outer circumferential side of the annular groove. The first annular surface protrudes toward the other of the adjustment cover and the pressure pad more than the second annular surface, and serves as a collision surface to which a collision load from the other of the adjustment cover and the pressure pad is input.

[0013] If a wide groove is provided in the annular groove, the wall thickness is reduced and the strength is lowered. Also, if an outer peripheral bulging surface is provided on the outer peripheral surface of the annular groove, the strength of the second annular surface is lowered. On the other hand, the strength of the first annular surface, which is the contact surface, is maintained. Therefore, even if an outer peripheral bulging surface is provided, the durability of one of the adjustment cover and the pressure pad is not impaired.

[0014] As one aspect of the above-described rack guide device, the inner circumferential surface has one or more inner circumferential arc surfaces extending in the circumferential direction with a predetermined diameter, and one or more inner circumferential bulging surfaces bulging radially inward of the inner circumferential arc surfaces. The outer circumferential surface has a constant diameter over the entire circumference. The narrow groove is disposed between the outer circumferential surface and the inner circumferential arc surface. The wide groove is disposed between the outer circumferential surface and the inner circumferential bulging surface.

[0015] As one aspect of the above-described rack guide device, the outer circumferential surface has one or more outer circumferential arc surfaces extending in the circumferential direction with a predetermined diameter, and one or more outer circumferential bulging surfaces bulging radially outward of the outer circumferential arc surfaces. The inner circumferential surface has one or more inner circumferential arc surfaces extending in the circumferential direction with a predetermined diameter, and one or more inner circumferential bulging surfaces bulging radially inward of the inner circumferential arc surfaces. The narrow groove is disposed between the outer circumferential arc surface and the inner circumferential arc surface. The wide groove is disposed between the outer circumferential bulging surface and the inner circumferential arc surface, between the outer circumferential arc surface and the inner circumferential bulging surface, or between the outer circumferential bulging surface and the inner circumferential bulging surface.

[0016] As one aspect of the above-described rack guide device, the cross-sectional shape of the O-ring before assembly may be circular.

[0017] As one aspect of the above-described rack guide device, the cross-sectional shape of the O-ring before assembly may be rectangular.

[0018] As a desirable aspect of the above-described rack guide device, the inner surface of the annular groove has a bottom surface. The bottom surface has a first bottom surface and a second bottom surface spaced apart from the opposing surface more than the first bottom surface. The bottom surface of the narrow groove is the first bottom surface. The bottom surface of the wide groove is the second bottom surface.

[0019] In the step of assembling the O-ring into the annular groove, after the O-ring abuts against the first bottom surface, it is necessary to further push the O-ring in. According to this, the gaps at the inner circumferential corners between the inner circumferential surface and the bottom surface and the gaps at the outer circumferential corners between the outer circumferential surface and the bottom surface become smaller, and the filling rate increases. According to the above configuration, when the O-ring abuts against the first bottom surface, a radial gap extending in the radial direction is generated between the O-ring and the second bottom surface. This radial gap is continuous with the depth direction gap. Therefore, the air in the gaps at the outer circumferential corners and the inner circumferential corners moves to the outer circumferential side or the inner circumferential side through the radial gap, and then is discharged to the outside through the depth direction gap. Therefore, after the O-ring abuts against the first bottom surface, the operation of further pushing the O-ring in becomes easy.

[0020] To achieve the above object, a steering device according to one aspect of the present disclosure includes the rack bar extending in the left-right direction of the vehicle, a pinion meshing with the rack bar, and the above-described rack guide device.

[0021] According to the above-described steering device, the air in the annular groove is discharged, and the O-ring can be pushed in with a small force. Therefore, it becomes easy to assemble the O-ring into the annular groove.

Effects of the Invention

[0022] According to the guide device and the steering device of the present disclosure, the O-ring can be easily assembled into the annular groove.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Best Mode for Carrying Out the Invention

[0024] Hereinafter, the present disclosure will be described in detail with reference to the drawings. Note that the present disclosure is not limited by the following embodiments for carrying out the invention (hereinafter referred to as embodiments). In addition, the constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those within a so-called equivalent range. Furthermore, the constituent elements disclosed in the following embodiments can be combined as appropriate.

[0025] (Embodiment 1) FIG. 1 is a schematic diagram of an electric power steering apparatus according to Embodiment 1. FIG. 2 is a cross-sectional view of the housing according to Embodiment 1 cut in a direction parallel to the rack bar. The electric power steering apparatus 80 is an apparatus mounted on the front part of a vehicle body for steering wheels. As shown in FIG. 1, the electric power steering apparatus 80 includes a steering wheel 81, a steering column shaft 82, a universal joint 83, an intermediate shaft 84, a universal joint 85, a steering pinion 86, a rack bar 87, an assist device 90, a housing 91, and a rack guide device 1.

[0026] The steering wheel 81 is connected to the steering column shaft 82. The steering column shaft 82, the intermediate shaft 84, and the steering pinion 86 are connected via universal joints 83 and 85. As shown in FIG. 2, the steering pinion 86 meshes with a first rack 88 of the rack bar 87. The rack bar 87 has a pressed surface 89 on the back side of the first rack 88. The pressed surface 89 is pressed by a pressure pad 30 of the rack guide device 1 (see arrow A in FIG. 2). Thereby, the rack bar 87 is pressed toward the steering pinion 86, and the meshing between the steering pinion 86 and the first rack 88 is maintained.

[0027] As shown in FIG. 1, the rack bar 87 is supported by the housing 91 so as to be movable in the vehicle width direction of the vehicle (the directions indicated by the arrows X1 and X2 in FIGS. 1 and 2). Both ends 87a and 87b of the rack bar 87 are connected to wheels (not shown) via tie rods 92. When the steering wheel 81 is operated by the driver, the operating torque is transmitted to the steering pinion 86, and the steering pinion 86 rotates about the rotation axis O1 (see FIG. 2). As a result, the rack bar 87 moves in the left - right direction of the vehicle (see the arrows X1 and X2 in FIGS. 1 and 2), and the wheels are steered.

[0028] The assist device 90 is a part that generates power (assist force) for moving the rack bar 87. Although not particularly shown, the assist device 90 includes a control device, a motor, and a power transmission device. The control device receives a detection signal from a torque sensor that detects the input torque to the steering pinion 86. Then, the control device drives the motor and controls the motor to output a desired assist torque. The power transmission device transmits the rotational motion of the motor to the rack bar. The power transmission device includes a worm integral with the output shaft of the motor, a worm wheel meshing with the worm, and an assist pinion that rotates integrally with the worm wheel. The assist pinion meshes with a second rack (not shown) provided on the rack bar 87. Therefore, an assist force acts on the rack bar 87 by driving the motor.

[0029] Next, the details of the rack guide device 1 will be described. FIG. 3 is an enlarged view of the rack guide device in FIG. 2. FIG. 4 is a view of the adjuster cover of Embodiment 1 as viewed from the first direction. FIG. 5 is an enlarged view of a part of FIG. 3. As shown in FIG. 3, the rack guide device 1 has a housing wall portion 2, an adjuster cover 10, a pressure pad 30, a coil spring 40, and O - rings (a first O - ring 51, a second O - ring 52, and a third O - ring 53).

[0030] The housing wall portion 2 is a cylindrical wall portion (thick portion) integrally provided on the housing 91. The housing wall portion 2 has an internal space S and two openings (first opening S1, second opening S2). The internal space S extends along the center line O3. This center line O3 is orthogonal to the center line O2 of the rack bar 87. That is, the internal space S extends in a direction orthogonal to the rack bar 87. And one of the two openings (first opening S1) opens toward the pressed surface 89 of the rack bar 87. The other of the two openings (second opening S2) opens in a direction opposite to the rack bar 87.

[0031] Hereinafter, the direction parallel to the center line O3 is referred to as the orthogonal direction. Also, among the orthogonal directions, the side where the first opening S1 is located when viewed from the internal space S is referred to as the first direction Y1. Among the orthogonal directions, the side where the second opening S2 is located when viewed from the internal space S is referred to as the second direction Y2.

[0032] On the inner peripheral surface 3 of the housing wall portion 2, an internal thread portion 4 and a sliding surface 5 are provided. The internal thread portion 4 is provided near the second opening S2. The sliding surface 5 is a cylindrical surface centered on the center line O3 and is provided from the central portion in the orthogonal direction to the end portion in the first direction Y1 of the inner peripheral surface 3. Also, an inner peripheral stepped surface 6 is provided between the internal thread portion 4 and the sliding surface 5.

[0033] The adjustment cover 10 is a member that closes the second opening S2 of the housing wall portion 2 and has a disk shape. An external thread portion 12 is provided on the outer peripheral surface 11 of the adjustment cover 10. The external thread portion 12 is screwed into the internal thread portion 4 of the housing wall portion 2. Thereby, the adjustment cover 10 is fixed to the housing wall portion 2.

[0034] An outer peripheral stepped surface 13 is provided at the end portion in the first direction Y1 of the outer peripheral surface 11 of the adjustment cover 10. This outer peripheral stepped surface 13 faces the inner peripheral stepped surface 6. And a first O-ring 51 is disposed between the inner peripheral stepped surface 6 and the outer peripheral stepped surface 13. Thereby, the space between the housing wall portion 2 and the adjustment cover 10 is sealed. Therefore, the grease in the housing 91 hardly flows out to the outside of the housing wall portion 2.

[0035] In the central portion of the adjustment cover 10, a through hole 14 penetrating in the orthogonal direction is provided. This through hole 14 is a hole for inserting a dial gauge when measuring the position in the orthogonal direction of the pressure pad 30. Further, a cap 41 is inserted into the through hole 14 from the second direction Y2, and the through hole 14 is sealed. The adjustment cover 10 has an opposing surface 20 facing the first direction Y1. This opposing surface 20 forms the bottom surface of the internal space S.

[0036] As shown in FIG. 4, on the opposing surface 20, a first accommodation hole 21, a first annular surface 22, an annular groove 23, and a second annular surface 24 are provided in order from the center line O3 toward the radially outer side. In FIG. 4, in order to make the annular groove 23 easier to see, dots are attached to the range of the annular groove 23.

[0037] The first accommodation hole 21 is a depression provided in the opposing surface 20. The first accommodation hole 21 has a cylindrical shape centered on the center line O3. As shown in FIG. 5, a part of the coil spring 40 (the part closer to the second direction Y2) is accommodated in the first accommodation hole 21. The central portion of the bottom surface 21a of the first accommodation hole 21 is hollowed out by the through hole 14. Therefore, the bottom surface 21a of the first accommodation hole 21 is annular (see FIG. 4). And the end portion of the coil spring 40 in the second direction Y2 abuts on the bottom surface 21a.

[0038] As shown in FIG. 4, the first annular surface 22 is an annular (circular) surface disposed between the first accommodation hole 21 and the annular groove 23. The second annular surface 24 is an annular (circular) surface disposed on the outer peripheral side of the annular groove 23. As shown in FIG. 5, the first annular surface 22 forms a plane perpendicular to the center line O3. The second annular surface 24 is inclined so as to be positioned in the second direction Y2 as it goes radially outward. That is, the second annular surface 24 forms a tapered surface. For this reason, the first annular surface 22 is disposed in the first direction Y1 with respect to the second annular surface 24 (see the auxiliary line H).

[0039] The annular groove 23 is a recess provided on the opposing surface 20. The annular groove 23 forms an annular (circular) shape centered on the center line O3. The second O-ring 52 is pushed into the annular groove 23 from the first direction Y1, and the second O-ring 52 is fitted in the annular groove 23. Also, as the second O-ring 52, one having a crush allowance is used with respect to the annular groove 23. Therefore, the filling rate of the second O-ring 52 in the annular groove 23 is high. Also, a part of the second O-ring 52 protrudes in the first direction Y1 from the opposing surface 20 (the first annular surface 22). Details of the annular groove will be described later.

[0040] As shown in FIG. 3, the pressure pad 30 is a cylindrical component centered on the center line O3. The end portion of the pressure pad 30 in the first direction Y1 protrudes into the housing 91 from the first opening S1. A guide portion 39 made of resin is provided on the end surface 31 of the pressure pad 30 in the first direction Y1. And this guide portion 39 is in contact with the pressed surface 89 of the rack bar 87.

[0041] The outer peripheral surface 32 of the pressure pad 30 faces the sliding surface 5 of the housing wall portion 2. As shown in FIG. 5, a minute gap is provided between the outer peripheral surface 32 of the pressure pad 30 and the sliding surface 5 of the housing wall portion 2. Thereby, the pressure pad 30 is supported by the housing wall portion 2 so as to be slidable in the orthogonal direction.

[0042] As shown in FIG. 3, two accommodation grooves 34 are provided on the outer peripheral surface 32 of the pressure pad 30. The accommodation grooves 34 are annular centered on the center line O3. The third O-ring 53 is fitted in the accommodation grooves 34. Thereby, the grease in the housing 91 is less likely to flow out in the second direction Y2 (outside the housing wall portion 2) through between the sliding surface 5 and the pressure pad 30.

[0043] As shown in FIG. 5, the pressure pad 30 has a back surface 35 facing the second direction Y2. The back surface 35 faces the opposing surface 20. The back surface 35 is a plane perpendicular to the center line O3. Also, a gap is provided between the opposing surface 20 and the back surface 35 to allow the pressure pad 30 to move in the second direction Y2. The second O-ring 52 is in contact with the back surface 35.

[0044] As shown in FIG. 3, a circular second accommodation hole 36 recessed in the first direction Y1 is provided at the center of the back surface 35. A part of the coil spring 40 (the part closer to the first direction Y1) is accommodated in the second accommodation hole 36. And the end of the coil spring 40 in the first direction Y1 is in contact with the bottom surface of the second accommodation hole 36. Also, the coil spring 40 is assembled between the adjustment cover 10 and the pressure pad 30 in a state of being compressed in the orthogonal direction. Thus, the pressure pad 30 is pressed in the first direction Y1 by the restoring force of the coil spring 40.

[0045] According to the rack guide device 1 of the above-described Embodiment 1, when vibration from the road surface is input to the rack bar 87 and the rack bar 87 and the pressure pad 30 move in the second direction Y2, the back surface 35 of the pressure pad 30 contacts the opposing surface 20 (the first annular surface 22) of the adjustment cover 10. Thereby, an impact load is input to the part where the first annular surface 22 is provided on the adjustment cover 10.

[0046] Also, due to the movement of the pressure pad 30 in the second direction Y2, the second O-ring 52 is crushed (deformed). Therefore, the impact load input to the first annular surface 22 is reduced. After the back surface 35 contacts the opposing surface 20 (the first annular surface 22), the pressure pad 30 and the rack bar 87 are pressed in the first direction Y1 by the restoring force of the coil spring 40. And the first rack 88 of the rack bar 87 meshes with the steering pinion 86.

[0047] In addition, the pressure pad 30 may tilt within the internal space S. That is, a part of the outer peripheral side of the back surface 35 of the pressure pad 30 may approach the second annular surface 24. However, the second annular surface 24 is a tapered surface. Therefore, the back surface 35 is prevented from contacting the second annular surface 24.

[0048] Next, the details of the annular groove 23 and the second O-ring 52 will be described. FIG. 6 is a cross-sectional view taken along the line VI-VI of FIG. 4. FIG. 7 is a cross-sectional view taken along the line VII-VII of FIG. 4. As shown in FIG. 6, the inner surface of the annular groove 23 has an inner peripheral surface 25 and an outer peripheral surface 26 facing each other, and a bottom surface 27 facing the first direction Y1.

[0049] The inner peripheral surface 25 is a side surface facing radially outward. The outer peripheral surface 26 is a side surface facing radially inward. As shown in FIG. 4, when viewed from the first direction Y1, the inner peripheral surface 25 forms a circular shape centered on the center line O3. That is, the inner peripheral surface 25 has a constant diameter over the entire circumference. On the other hand, when viewed from the first direction Y1, the outer peripheral surface 26 generally forms a circular shape centered on the center line O3, and a part of it bulges radially outward. That is, the outer peripheral surface 26 has a plurality of outer peripheral arc surfaces 26a extending in the circumferential direction with a predetermined diameter, and a plurality of outer peripheral bulging surfaces 26b bulging radially outward from the outer peripheral arc surfaces 26a.

[0050] And the portion disposed between the outer peripheral arc surface 26a and the inner peripheral surface 25 forms a narrow groove 28. On the other hand, the portion disposed between the outer peripheral arc surface 26a and the inner peripheral surface 25 forms a wide groove 29. That is, the annular groove 23 includes a narrow groove 28 and a wide groove 29 having different groove widths.

[0051] In addition, in the present embodiment, the outer peripheral bulging surfaces 26b are arranged at 90° intervals, and a total of four are provided. The outer peripheral arc surfaces 26a are arranged between two outer peripheral bulging surfaces 26b, and a total of four are provided. Therefore, four narrow grooves 28 and four wide grooves 29 are provided respectively. In addition, the bottom surface 27 of the present embodiment has a constant distance from the facing surface 20 over the entire circumference.

[0052] As shown in Fig. 6, the second O-ring 52 before being assembled into the annular groove 23 has a circular cross-sectional shape. Also, the wire diameter of the second O-ring 52 before being assembled into the annular groove 23 is W1. The groove width of the narrow groove 28 is W2. This groove width W2 is smaller than the wire diameter W1. Therefore, the second O-ring 52 has a crushing allowance with respect to the narrow groove 28. As shown in Fig. 7, the groove width of the wide groove 29 is W3. This groove width W3 is larger than the wire diameter W1. Therefore, the second O-ring 52 does not have a crushing allowance with respect to the wide groove 29.

[0053] Next, the process of assembling the second O-ring 52 into the annular groove 23 will be described. Fig. 8 is a cross-sectional view showing the point in time when the second O-ring abuts against the pressure pad during the attachment process of the adjustment cover. Fig. 9 is a cross-sectional view showing the point in time when the second O-ring is being pressed by the pressure pad during the attachment process of the adjustment cover. Fig. 10 is a cross-sectional view showing the state where the attachment of the adjustment cover is completed during the attachment process of the adjustment cover. Fig. 11 is a cross-sectional view of the wide groove in a state where the second O-ring is being pressed by the pressure pad.

[0054] The assembly of the second O-ring 52 is performed simultaneously with attaching the adjustment cover 10 to the housing wall portion 2. Specifically, a part of the second O-ring 52 is press-fitted into the annular groove 23, and the second O-ring 52 is temporarily fixed to the adjustment cover 10. Next, while rotating the adjustment cover 10 around the center line O3, it is inserted into the second opening of the housing wall portion 2 as S2. As a result, the second O-ring 52 moves the internal space S of the housing wall portion 2 in the first direction Y1. Then, as shown in Fig. 8, the second O-ring 52 abuts against the back surface 35 of the pressure pad 30.

[0055] Continuing, when the adjustment cover 10 is rotated, the adjustment cover 10 moves in the first direction Y1. The second O-ring 52 is pressed from the back surface 35 in the second direction Y2 and pushed into the annular groove 23. As a result, as shown in FIG. 9, the second O-ring 52 is sandwiched between the inner peripheral surface 25 and the outer peripheral arc surface 26a in the narrow groove 28. That is, the second O-ring 52 is crushed under a radial compressive load from the inner peripheral surface 25 and the outer peripheral arc surface 26a. Therefore, the cross-sectional shape of the second O-ring 52 is not circular, but gradually approximates the shape of the narrow groove 28.

[0056] Continuing, when the adjustment cover 10 is rotated, the second O-ring 52 is pressed against the back surface 35 and abuts on the bottom surface 27. Then, after the second O-ring 52 abuts on the bottom surface 27, it is further pressed from the back surface 35 and receives an orthogonal compressive load from the bottom surface 27 and the back surface 35. As a result, the second O-ring 52 is filled up to the vicinity of the inner peripheral corner 15 between the bottom surface 27 and the inner peripheral surface 25 and the outer peripheral corner 16 between the bottom surface 27 and the outer peripheral surface 26. Therefore, the second O-ring 52 has a cross-sectional shape following the inner surface of the narrow groove 28. That is, the filling rate of the second O-ring 52 in the narrow groove 28 is high.

[0057] Here, as shown in FIG. 9, when the second O-ring 52 is sandwiched between the inner peripheral surface 25 and the outer peripheral arc surface 26a, a closed space Q1 surrounded by the second O-ring 52, the inner peripheral surface 25, the outer peripheral arc surface 26a, and the bottom surface 27 is generated in the narrow groove 28. Assuming that there is no escape hole for discharging the air in the closed space Q1, when the second O-ring 52 is further moved in the second direction Y2 from the state shown in FIG. 9, the air in the closed space Q1 is compressed. This compressed air exerts a resistance force to move the second O-ring 52 in the first direction Y1.

[0058] On the other hand, as shown in FIG. 11, with respect to the wide groove 29, the second O-ring 52 has no interference fit. That is, in the wide groove 29, the second O-ring 52 is not sandwiched between the inner peripheral surface 25 and the outer peripheral bulging surface 26b. For this reason, a gap is generated between the second O-ring 52 and the outer peripheral bulging surface 26b. Since this gap extends in the depth direction of the annular groove 23, it is hereinafter referred to as a depth direction gap Q2.

[0059] Further, the depth-direction gap Q2 extends toward the bottom surface 27 and is continuous with the closed space Q1. Therefore, when the second O-ring 52 is pushed into the second direction Y2 from the state where the second O-ring 52 is sandwiched between the inner peripheral surface 25 and the outer peripheral arc surface 26a, the air in the closed space Q1 is pushed out toward the depth-direction gap Q2 and discharged to the outside of the annular groove 23. Since the air in the closed space Q1 does not exert resistance, the second O-ring 52 can be pushed into the annular groove 23 with a small force.

[0060] In addition, in FIG. 11, the case where the depth-direction gap Q2 is generated between the second O-ring 52 and the outer peripheral bulging surface 26b is illustrated. However, the depth-direction gap Q2 of the present embodiment may be generated between the second O-ring 52 and the inner peripheral surface 25, or may be generated both between the second O-ring 52 and the outer peripheral bulging surface 26b and between the second O-ring 52 and the inner peripheral surface 25.

[0061] The process of assembling the second O-ring 52 into the annular groove 23 has been described above. Further, according to the present embodiment, since the outer peripheral bulging surface 26b is provided on the opposing surface 20, a part of the meat portion is cut out and the strength of the adjustment cover 10 is reduced. However, the surface cut out by the outer peripheral bulging surface 26b is the second annular surface 24, not the first annular surface 22. Therefore, the strength of the first annular surface 22 in contact with the pressure pad 30 is maintained.

[0062] As described above, the electric power steering apparatus (steering apparatus) 80 of Embodiment 1 includes a rack bar 87 extending in the left - right direction of the vehicle, a pinion (steering pinion 86) meshing with the rack bar 87, and a rack guide device 1. The rack guide device 1 includes an internal space S extending in a direction orthogonal to the rack bar 87, a first opening S1 opening from the internal space S toward the rack bar 87, a second opening S2 opening from the internal space S in a direction opposite to the rack bar 87, a housing wall portion 2 having these, an adjustment cover 10 closing the second opening S2 of the housing wall portion 2, a pressure pad 30 disposed in the internal space S and contacting the rack bar 87 from the first opening S1, and a coil spring 40 and an O - ring (second O - ring 52) disposed between the adjustment cover 10 and the pressure pad 30. One of the adjustment cover 10 and the pressure pad 30 has a facing surface 20 facing the other of the adjustment cover 10 and the pressure pad 30. An annular groove 23 in which the O - ring (second O - ring 52) is assembled is provided on the facing surface 20. The inner surface of the annular groove 23 has an inner peripheral surface 25 and an outer peripheral surface 26 facing each other. The annular groove 23 has a narrow - width groove 28 in which the groove width between the inner peripheral surface 25 and the outer peripheral surface 26 is smaller than the wire diameter W1 of the O - ring (second O - ring 52) before assembly, and a wide - width groove 29 in which the groove width is larger than the wire diameter W1 of the O - ring (second O - ring 52) before assembly.

[0063] According to Embodiment 1, the filling rate of the second O - ring 52 in the narrow - width groove 28 is high. Therefore, the pressure pad 30 is less likely to contact the adjustment cover 10, and the generation of contact noise can be suppressed. Also, when the second O - ring 52 is assembled, the air in the closed space Q1 is discharged from the depth - direction gap Q2. Therefore, the second O - ring 52 can be pushed into the annular groove 23 with a small force. Thus, it becomes easy to assemble the second O - ring 52 into the annular groove 23.

[0064] Further, the outer peripheral surface 26 of the annular groove 23 in Embodiment 1 has (one or) a plurality of outer peripheral arc surfaces 26a extending in the circumferential direction with a predetermined diameter, and (one or) a plurality of outer peripheral bulging surfaces 26b bulging radially outward of the outer peripheral arc surface 26a. The inner peripheral surface 25 has a constant diameter over the entire circumference. The narrow groove 28 is disposed between the outer peripheral arc surface 26a and the inner peripheral surface 25. The wide groove 29 is disposed between the outer peripheral bulging surface 26b and the inner peripheral surface 25.

[0065] Further, the opposing surface 20 in Embodiment 1 has a first annular surface 22 disposed on the inner peripheral side of the annular groove 23 and a second annular surface 24 disposed on the outer peripheral side of the annular groove 23. The first annular surface 22 protrudes toward the pressure pad 30 (the other of the adjustment cover 10 and the pressure pad 30) more than the second annular surface 24, and serves as a collision surface to which a collision load from the pressure pad 30 (the other of the adjustment cover 10 and the pressure pad 30) is input.

[0066] According to Embodiment 1, even if the outer peripheral bulging surface 26b is provided on the opposing surface 20, the strength of the first annular surface 22 is maintained. Therefore, the durability of the adjustment cover 10 is retained.

[0067] Further, in Embodiment 1, the cross-sectional shape of the O-ring (the second O-ring 52) before assembly is circular.

[0068] As described above, Embodiment 1 has been described, but the present disclosure is not limited to the example shown in Embodiment 1. In Embodiment 1, an example applied to the electric power steering apparatus 80 provided with the assist device has been given, but the present disclosure may be applied to a steering apparatus not provided with the assist device. Further, when the assist device has an assist pinion, the present disclosure may be applied to a rack guide device that presses the rack bar 87 toward the assist pinion. Further, regarding the O-ring (the second O-ring 52), in the present embodiment, the cross-sectional shape before assembly is circular, but the present disclosure may have a rectangular cross-sectional shape before assembly and is not particularly limited.

[0069] In addition, in Embodiment 1, four wide grooves 29 are provided. However, in the present disclosure, only one wide groove 29 may be provided, and there is no limitation on the number of wide grooves 29. Further, in Embodiment 1, the four wide grooves 29 are arranged at equal intervals in the circumferential direction. However, in the present disclosure, they do not have to be at equal intervals. Further, the wide groove 29 of Embodiment 1 is composed of a bulging outer peripheral surface and an inner peripheral surface. However, the present disclosure is not limited thereto. Hereinafter, wide grooves according to other embodiments will be described. In the following description, the description will be focused on the differences from the rack guide device 1 of Embodiment 1.

[0070] (Embodiment 2) FIG. 12 is a view of the adjuster cover of Embodiment 2 as viewed from the first direction. The rack guide device 1A of Embodiment 2 is different from Embodiment 1 in that the outer peripheral surface 26 of the annular groove 23 has a constant diameter over the entire circumference. Further, the inner peripheral surface 25 of the annular groove 23 is different from Embodiment 1 in that it has four inner peripheral arc surfaces 25a extending in the circumferential direction with a predetermined diameter and four inner peripheral bulging surfaces 25b bulging radially inward of the inner peripheral arc surfaces 25a.

[0071] Therefore, the narrow groove 28A of Embodiment 2 is disposed between the outer peripheral surface 26 and the inner peripheral arc surface 25a. Further, the wide groove 29A is disposed between the outer peripheral surface 26 and the inner peripheral bulging surface 25b. According to Embodiment 2, when the second O-ring 52 is assembled, a depth direction gap Q2 is generated between the second O-ring 52 and the outer peripheral surface 26, or between the second O-ring 52, the outer peripheral surface 26, and the inner peripheral bulging surface 25b. Therefore, the air in the closed space Q1 is pushed out by the second O-ring 52, flows toward the depth direction gap Q2, and is discharged from the annular groove 23. Therefore, the second O-ring 52 can be easily assembled into the annular groove 23.

[0072] Note that four inner peripheral bulging surfaces 25b and wide grooves 29A are provided in Embodiment 2. However, in the present disclosure, only one may be provided, and there is no limitation on the number of inner peripheral bulging surfaces 25b and wide grooves 29A.

[0073] (Embodiment 3) FIG. 13 is a view of the adjuster cover of Embodiment 3 as viewed from the first direction. The rack guide device 1B of Embodiment 3 is different from Embodiment 1 with respect to the inner peripheral surface 25 of the annular groove 23. Specifically, the inner peripheral surface 25 is different from Embodiment 1 in that it has four inner peripheral arc surfaces 25a extending in the circumferential direction with a predetermined diameter, and four inner peripheral bulging surfaces 25b bulging radially inward of the inner peripheral arc surface 25a. Further, the inner peripheral bulging surface 25b is arranged with a 45° shift with respect to the outer peripheral bulging surface 26b. That is, the inner peripheral bulging surface 25b and the outer peripheral bulging surface 26b are arranged with a shift in the circumferential direction with respect to each other.

[0074] Therefore, the narrow groove 28B of Embodiment 3 is arranged between the outer peripheral arc surface 26a and the inner peripheral arc surface 25a. Further, the wide groove 29B is arranged between the outer peripheral arc surface 26a and the inner peripheral bulging surface 25b and between the outer peripheral bulging surface 26b and the inner peripheral arc surface 25a. As described above, the rack guide device 1B of Embodiment 3 has eight wide grooves 29B. When the second O-ring 52 is assembled, the air in the closed space Q1 flows into the depth direction gap Q2 and is discharged from the annular groove 23. Therefore, the second O-ring 52 can be easily assembled into the annular groove 23.

[0075] As described above, Embodiment 3 has been described, but in the present disclosure, the inner peripheral bulging surface 25b and the outer peripheral bulging surface 26b may overlap in the radial direction. In such a case, the wide groove 29B is arranged between the outer peripheral bulging surface 26b and the inner peripheral bulging surface 25b.

[0076] (Embodiment 4) FIG. 14 is a view of the adjuster cover according to Embodiment 4 as viewed from the first direction. FIG. 15 is a cross-sectional view at the time when the second O-ring contacts the first bottom surface in Embodiment 4, and more specifically, a cross-sectional view taken along the line XV-XV in FIG. 14. As shown in FIG. 14, the rack guide device 1C according to Embodiment 4 is different from Embodiment 1 in that the number of outer peripheral bulging surfaces is reduced from four to one. Further, the bottom surface 27 of the annular groove 23 is different from that of Embodiment 1 in that it has a first bottom surface 27a and a second bottom surface 27b. As shown in FIG. 15, the second bottom surface 27b is disposed in the second direction Y2 with respect to the first bottom surface 27a. That is, the second bottom surface 27b is separated from the opposing surface 20 more than the first bottom surface 27a. The bottom surface 27 of the narrow groove 28 is the first bottom surface 27a. The bottom surface 27 of the wide groove 29 is the second bottom surface 27b.

[0077] Next, the effects of the rack guide device 1C according to Embodiment 4 will be described. As shown in FIG. 15, in the step of assembling the second O-ring 52 into the annular groove 23, the second O-ring 52 is pushed into the annular groove 23 from the first direction Y1. Therefore, as shown in FIG. 15, the second O-ring 52 contacts the first bottom surface 27a. Then, by further pushing in the second O-ring 52, the second O-ring 52 is crushed and the filling rate increases.

[0078] Here, in the narrow groove 28C, when the second O-ring 52 contacts the first bottom surface 27a, an inner peripheral gap Q3 is generated at the inner peripheral corner 15, and an outer peripheral gap Q4 is generated at the outer peripheral corner 16. Further, in the wide groove 29C, the second O-ring 52 does not contact the second bottom surface 27b. Therefore, a radial gap Q5 extending in the radial direction is generated between the second O-ring 52 and the second bottom surface 27b.

[0079] This radial gap Q5 extends from the inner peripheral surface 25 to the outer peripheral bulging surface 26b and is continuous with the depth direction gap Q2. The inner peripheral gap Q3 at the inner peripheral corner 15 and the outer peripheral gap Q4 at the outer peripheral corner 16 are continuous in the circumferential direction and form an annulus. And a part of the inner peripheral gap Q3 at the inner peripheral corner 15 is continuous with the radial gap Q5 in the circumferential direction. Further, a part of the outer peripheral gap Q4 at the outer peripheral corner 16 is continuous with the depth direction gap Q2 in the circumferential direction.

[0080] Therefore, when the second O-ring 52 abuts against the first bottom surface 27a and the second O-ring 52 is further pushed in, the air in the inner peripheral gap Q3 is pushed toward the radial gap Q5. Then, the air that has moved to the radial gap Q5 moves toward the depth-direction gap Q2 and is discharged from the annular groove 23. Also, the air in the outer peripheral gap Q4 is pushed toward the depth-direction gap Q2 and is discharged from the annular groove 23.

[0081] Therefore, when the second O-ring 52 abuts against the first bottom surface 27a and the second O-ring 52 is further pushed in, the air resistance acting on the second O-ring 52 is small. Thus, the second O-ring 52 can be pushed in with a small force, and it becomes easy to assemble the second O-ring into the annular groove 23.

[0082] As described above, although the fourth embodiment has been explained, the second bottom surface 27b may be applied to the bottom surface 27 of the wide groove 29A disposed between the outer peripheral surface 26 and the inner peripheral bulging surface 25b shown in the second embodiment. Also, in the present embodiment, the opposing surface 20 having the annular groove 23 is provided on the side of the adjustment cover 10, and the second O-ring 52 is assembled. However, the present disclosure is not limited to this. That is, the back surface 35 of the pressure pad 30 may be used as the opposing surface 20, the annular groove 23 may be provided in the pressure pad 30, and the second O-ring 52 may be assembled.

[0083] Also, the present disclosure may be a combination of the following configurations. (1) A housing wall portion having an internal space extending in a direction orthogonal to the rack bar, a first opening opening from the internal space toward the rack bar, and a second opening opening from the internal space in a direction opposite to the rack bar, An adjustment cover that closes the second opening of the housing wall portion, A pressure pad disposed in the internal space and abutting against the rack bar from the first opening, A coil spring and an O-ring disposed between the adjustment cover and the pressure pad, Comprising One of the adjustment cover and the pressure pad has a facing surface facing the other of the adjustment cover and the pressure pad, An annular groove for assembling the O-ring is provided on the facing surface, The inner surface of the annular groove has an inner peripheral surface and an outer peripheral surface facing each other, The annular groove is A narrow-width groove in which the groove width between the inner peripheral surface and the outer peripheral surface is smaller than the wire diameter of the O-ring before assembly, A wide-width groove in which the groove width is larger than the wire diameter of the O-ring before assembly, and has Rack guide device. (2) The outer peripheral surface is One or more outer peripheral arc surfaces extending in the circumferential direction with a predetermined diameter, One or more outer peripheral bulging surfaces bulging radially outward from the outer peripheral arc surface, and has The inner peripheral surface has a constant diameter over the entire circumference, The narrow-width groove is disposed between the outer peripheral arc surface and the inner peripheral surface, The wide-width groove is disposed between the outer peripheral bulging surface and the inner peripheral surface The rack guide device according to (1). (3) The facing surface is A first annular surface disposed on the inner peripheral side of the annular groove, A second annular surface disposed on the outer peripheral side of the annular groove, and has The first annular surface protrudes more toward the other of the adjustment cover and the pressure pad than the second annular surface, and is a collision surface into which a collision load from the other of the adjustment cover and the pressure pad is input. The rack guide device according to (2). (4) The inner peripheral surface is One or more inner peripheral arc surfaces extending in the circumferential direction with a predetermined diameter, One or more inner peripheral bulging surfaces bulging radially inward from the inner peripheral arc surface, has, the outer peripheral surface has a constant diameter over the entire circumference, the narrow groove is disposed between the outer peripheral surface and the inner peripheral arc surface, the wide groove is disposed between the outer peripheral surface and the inner peripheral bulging surface The rack guide device according to (1). (5) The outer peripheral surface, has one or more outer peripheral arc surfaces extending in the circumferential direction with a predetermined diameter, and one or more outer peripheral bulging surfaces bulging radially outward from the outer peripheral arc surface, has, The inner peripheral surface, has one or more inner peripheral arc surfaces extending in the circumferential direction with a predetermined diameter, and one or more inner peripheral bulging surfaces bulging radially inward from the inner peripheral arc surface, has, the narrow groove is disposed between the outer peripheral arc surface and the inner peripheral arc surface, the wide groove is disposed between the outer peripheral bulging surface and the inner peripheral arc surface, between the outer peripheral arc surface and the inner peripheral bulging surface, or between the outer peripheral bulging surface and the inner peripheral bulging surface The rack guide device according to (1). (6) The cross-sectional shape of the O-ring before assembly is circular The rack guide device according to any one of (1) to (5). (7) The cross-sectional shape of the O-ring before assembly is rectangular The rack guide device according to any one of (1) to (5). (8) The inner surface of the annular groove has a bottom surface, the bottom surface, has a first bottom surface, and a second bottom surface spaced apart from the facing surface more than the first bottom surface, has, the bottom surface of the narrow groove is the first bottom surface, the bottom surface of the wide groove is the second bottom surface The rack guide device according to any one of (1) to (7). (9) A rack bar extending in the left - right direction of the vehicle, A pinion meshing with the rack bar, The rack guide device according to any one of (1) to (8), A steering device comprising the same.

Explanation of Signs

[0084] 1, 1A, 1B, 1C Rack guide device 2 Housing wall part 10 Adjustment cover 30 Pressure pad 40 Coil spring 52 Second O - ring (O - ring) 20 Opposing surface 21 First accommodation hole 22 First annular surface 23 Annular groove 24 Second annular surface 25 Inner peripheral surface 25a Inner peripheral arc surface 25b Inner peripheral bulging surface 26 Outer peripheral surface 26a Outer peripheral arc surface 26b Outer peripheral bulging surface 27 Bottom surface 27a First bottom surface 27b Second bottom surface 28, 28A, 28B, 28C Narrow grooves 29, 29A, 29B, 29C Wide grooves 35 Rear surface 36 Second accommodation hole Q1 Closed space Q2 Depth - direction gap Q3 Inner - peripheral gap Q4 Outer - peripheral gap Q5 Radial - direction gap S Internal space S1 First opening S2 Second opening 80 Electric power steering device (Steering device) 86 Steering pinion (pinion) 87 Rack bar 89 Pressed surface 91 Housing

Claims

1. A housing wall portion having an internal space extending in a direction orthogonal to the rack bar, a first opening opening from the internal space toward the rack bar, and a second opening opening from the internal space in a direction opposite to the rack bar; An adjustment cover that closes the second opening of the housing wall portion; A pressure pad disposed in the internal space and contacting the rack bar from the first opening; A coil spring and an O-ring disposed between the adjustment cover and the pressure pad; Comprising; One of the adjustment cover and the pressure pad has a facing surface facing the other of the adjustment cover and the pressure pad; An annular groove for assembling the O-ring is provided on the facing surface; The inner surface of the annular groove has an inner circumferential surface and an outer circumferential surface facing each other; The annular groove is; A narrow-width groove in which the groove width between the inner circumferential surface and the outer circumferential surface is smaller than the wire diameter of the O-ring before assembly; A wide-width groove in which the groove width is larger than the wire diameter of the O-ring before assembly; Having; A rack guide device.

2. The outer circumferential surface is; One or more outer circumferential arc surfaces extending in the circumferential direction with a predetermined diameter; One or more outer circumferential bulging surfaces bulging radially outward from the outer circumferential arc surface; Having; The inner circumferential surface has a constant diameter over the entire circumference; The narrow-width groove is disposed between the outer circumferential arc surface and the inner circumferential surface; The wide-width groove is disposed between the outer circumferential bulging surface and the inner circumferential surface. The rack guide device according to Claim 1.

3. The facing surface is; A first annular surface disposed on the inner circumferential side of the annular groove; A second annular surface disposed on the outer circumferential side of the annular groove; Having; The first annular surface protrudes more toward the other of the adjustment cover and the pressure pad than the second annular surface, and is a collision surface into which a collision load from the other of the adjustment cover and the pressure pad is input. The rack guide device according to Claim 2.

4. The inner circumferential surface is; One or more inner circumferential arc surfaces extending in the circumferential direction with a predetermined diameter; One or more inner circumferential bulging surfaces bulging radially inward from the inner circumferential arc surface; Having; The outer circumferential surface has a constant diameter over the entire circumference; The narrow-width groove is disposed between the outer circumferential surface and the inner circumferential arc surface; The wide-width groove is disposed between the outer circumferential surface and the inner circumferential bulging surface. The rack guide device according to Claim 1.

5. The outer circumferential surface is; one or more outer peripheral arc surfaces extending in the circumferential direction with a predetermined diameter, one or more outer peripheral bulging surfaces bulging radially outward from the outer peripheral arc surfaces, and having, the inner peripheral surface is, one or more inner peripheral arc surfaces extending in the circumferential direction with a predetermined diameter, one or more inner peripheral bulging surfaces bulging radially inward from the inner peripheral arc surfaces, and having, the narrow groove is disposed between the outer peripheral arc surface and the inner peripheral arc surface, the wide groove is disposed between the outer peripheral bulging surface and the inner peripheral arc surface, between the outer peripheral arc surface and the inner peripheral bulging surface, or between the outer peripheral bulging surface and the inner peripheral bulging surface The rack guide device according to claim 1.

6. The cross-sectional shape of the O-ring before assembly is circular. The rack guide device according to claim 1.

7. The cross-sectional shape of the O-ring before assembly is rectangular. The rack guide device according to claim 1.

8. The inner surface of the annular groove has a bottom surface, the bottom surface is, a first bottom surface, a second bottom surface spaced from the opposing surface more than the first bottom surface, and having, the bottom surface of the narrow groove is the first bottom surface, the bottom surface of the wide groove is the second bottom surface The rack guide device according to claim 1.

9. the rack bar extending in the left-right direction of the vehicle, a pinion meshing with the rack bar, a rack guide device according to any one of claims 1 to 8, and a steering device comprising the same.

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