Dust cover

Abstract

To provide a dust cover that is less likely to generate a gap between a seal part and a steering shaft.SOLUTION: A dust cover includes: a cylindrical bushing fitted to an outer peripheral surface of a steering shaft and extending along a circumferential direction about a central axis; and a bellows for blocking a gap between a cylindrical member and the bushing. The bellows includes a seal part projecting toward the outer peripheral surface of a steering shaft and including a tip that abuts on the outer peripheral surface. The bellows is softer than the bushing.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present disclosure relates to a dust cover disposed in a gap between a steering shaft and a dash panel.

Background Art

[0002] [[ID=eleven]] A dust cover may be provided in a gap between a steering shaft of a vehicle and a through portion of a dash panel (see, for example, Patent Document 1). The dust cover described in Patent Document 1 includes a bellows, a cylindrical bush attached to the steering shaft, and two seal members vulcanized and adhered to one side and the other side in the axial direction of the bush. The tip of the seal member abuts against the outer peripheral surface of the steering shaft to suppress the intrusion of dust and the like from outside the vehicle compartment (for example, an engine room) into the vehicle compartment.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1, the bush is harder than the bellows, and the seal member is adhered to the bush. Therefore, when the axis of the bush is inclined with respect to the axis of the steering shaft, there is a possibility that the tip of the seal member is separated from the outer peripheral surface of the steering shaft and a gap is formed between the tip and the outer peripheral surface. That is, since the bush to which the seal member is adhered is hard, when the bush is displaced in the radial direction with respect to the steering shaft, the followability of the seal member is insufficient and a gap is formed between the tip and the outer peripheral surface, and there is a possibility that dust and the like enter from outside the vehicle compartment into the vehicle compartment.

[0005] This disclosure has been made in view of the above-mentioned problems, and aims to provide a dust cover that is less likely to create a gap between the seal portion and the steering shaft. [Means for solving the problem]

[0006] To achieve the above objective, a dust cover according to one aspect of the present disclosure includes a cylindrical bush attached to the outer circumferential surface of a steering shaft that penetrates a cylindrical member of a dash panel and extends in the axial direction of a central axis, and extending along the circumferential direction about the axis of the central axis, and a bellows that seals the gap between the cylindrical member and the bush, wherein the bellows includes a sealing portion that protrudes toward the outer circumferential surface of the steering shaft and whose tip abuts against the outer circumferential surface, and the bellows is softer than the bush.

[0007] As mentioned above, in the dust cover of Patent Document 1, since the sealing member is bonded to the bushing, if the bushing shifts radially relative to the steering shaft, the sealing member may not be able to follow the movement of the bushing, creating a gap between the tip and the outer surface, which could allow dust and other particles to enter the vehicle interior from outside.

[0008] In contrast, in this disclosure, the sealing portion is included in the bellows, and the bellows is softer than the bush. Therefore, compared to Patent Document 1, in which the sealing portion is bonded to the bush, the sealing portion becomes more flexible when the bush shifts radially relative to the steering shaft, and the contact between the tip of the sealing portion and the steering shaft is maintained more reliably. As a result, gaps are less likely to form between the tip of the sealing portion and the steering shaft, and the intrusion of dust and other particles from outside the vehicle into the vehicle interior is further suppressed.

[0009] In a preferred embodiment of the dust cover, the bellows comprises a cylindrical annular portion extending circumferentially along the outer circumference of the bush, a radial wall portion extending radially outward from the annular portion, and a bent portion bending axially from the radially outer end of the radial wall portion, with the sealing portion protruding from the radial wall portion toward the outer surface of the steering shaft. The annular portion is fixed to the bush, and the radial wall portion is connected to the annular portion. Therefore, the radial wall portion has higher rigidity than the bent portion. Consequently, even if the thickness of the sealing portion is reduced, the contact state between the tip of the sealing portion and the steering shaft is maintained, thereby reducing the cost of the sealing portion.

[0010] In a preferred embodiment of the dust cover, the bellows comprises a cylindrical annular portion extending circumferentially along the outer circumference of the bush, a radial wall portion extending radially outward from the annular portion, and a bent portion bending axially from the radially outer end of the radial wall portion, wherein the sealing portion protrudes from the bent portion toward the outer surface of the steering shaft.

[0011] The annular portion is fixed to the bush. The bent portion is connected to the annular portion via the radial wall portion. Therefore, the bent portion is more flexible than the annular portion and the radial wall portion. Consequently, by providing a seal portion in the bent portion, the flexibility of the seal portion is increased, and the contact between the tip of the seal portion and the steering shaft is maintained more reliably.

[0012] In a preferred embodiment of the dust cover, the sealing portion comprises a base portion joined to the radial wall portion, and a lip portion provided on the axial side of the base portion opposite to the radial wall portion and having a tip, wherein the radial inner end of the base portion is located radially inward from the inner circumferential surface of the annular portion, and the bush abuts against the annular portion and the base portion. In this way, because the bush abuts against the annular portion and the base portion, the bellows is less likely to shift axially relative to the bush.

[0013] In a desirable configuration of the dust cover, the bent portion and the base portion are separated radially and face each other. Therefore, even if the seal portion deforms radially when it comes into contact with the steering shaft, the seal portion is less likely to interfere with the bent portion.

[0014] In a preferred embodiment of the dust cover, the seal portion comprises a cylindrical portion extending circumferentially along the outer circumference of the bush, a first seal portion provided on one axial side of the cylindrical portion, with the tip on that axial side contacting the outer surface of the steering shaft, and a second seal portion provided on the other axial side of the cylindrical portion, with the tip on that axial side contacting the outer surface of the steering shaft. In this way, since the first seal portion and the second seal portion are connected via the cylindrical portion, the molding work of the seal portion becomes easier than when the first seal portion and the second seal portion are not connected.

[0015] In a preferred embodiment of the dust cover, the bellows comprises a cylindrical annular portion that extends along the outer circumference of the cylindrical portion and is joined to the outer circumference of the cylindrical portion. In this way, a sealing portion is formed by joining the cylindrical portion to the annular portion, making the molding work of the sealing portion easier.

[0016] In a desirable configuration of the dust cover, one of the annular portion and the cylindrical portion has a protrusion, and the other has a recess that fits into the protrusion. Therefore, the bonding strength between the annular portion and the cylindrical portion is increased.

[0017] In a preferred embodiment of the dust cover, the protrusion comprises a base portion and a tip portion provided at the tip of the base portion, wherein the axial length of the tip portion is greater than the axial length of the base portion. In this way, the tip portion is wider than the base portion, and the tip portion catches in the recess, thereby increasing the bonding strength between the annular portion and the cylindrical portion.

[0018] In a desirable embodiment of the dust cover, the annular portion and the cylindrical portion are two-color molded products, which makes it easier to mold the convex and concave portions.

[0019] As a desirable aspect of the dust cover, the bellows includes a first radially extending wall portion that extends radially outward from one axial side in the cylindrical portion, and a second radially extending wall portion that extends radially outward from the other axial side on the outer circumference of the cylindrical portion. Therefore, since each of the first radially extending wall portion and the second radially extending wall portion can be joined to the cylindrical portion, the joining operation becomes easier.

[0020] As a desirable aspect of the dust cover, each radially inner end portion of the first radially extending wall portion and the second radially extending wall portion has a convex portion that protrudes axially, and the cylindrical portion has a concave portion that fits into the convex portion. Therefore, the bonding strength between the radially inner end portion of the first radially extending wall portion and the cylindrical portion, and the bonding strength between the radially inner end portion of the second radially extending wall portion and the cylindrical portion are increased.

[0021] As a desirable aspect of the dust cover, each radially inner end portion of the first radially extending wall portion and the second radially extending wall portion has an axial distance that increases as it goes radially inward and has a joint portion that is joined to the outer circumference of the cylindrical portion. Thus, the axial distance of the joint portion joined to the outer circumference of the cylindrical portion is larger than the axial distance of other portions. Therefore, since the joint area with the cylindrical portion becomes larger, the joint strength between each of the first radially extending wall portion and the second radially extending wall portion and the cylindrical portion becomes larger.

[0022] As a desirable aspect of the dust cover, since the joint portion is adhered to the outer circumference of the cylindrical portion, the joining of the first radially extending wall portion and the second radially extending wall portion to the cylindrical portion becomes easier.

Advantages of the Invention

[0023] According to the present disclosure, it is possible to provide a dust cover in which a gap hardly occurs between the seal portion and the steering shaft.

Brief Description of the Drawings

[0024] [Figure 1] FIG. 1 is a schematic view of a steering apparatus according to a first embodiment. [Figure 2]FIG. 2 is a perspective view of the steering device according to the first embodiment. [Figure 3] FIG. 3 is a cross-sectional view of a dust cover attached to a vehicle. [Figure 4] FIG. 4 is a front view of the dust cover according to the first embodiment. [Figure 5] FIG. 5 is a cross-sectional view taken along the line V-V in FIG. 4. [Figure 6] FIG. 6 is a cross-sectional view showing the bellows of FIG. 5. [Figure 7] FIG. 15 is a cross-sectional view of the dust cover according to the second embodiment. [Figure 8] FIG. 8 is a cross-sectional view showing a part of FIG. 7. [Figure 9] FIG. 9 is a cross-sectional view of the dust cover according to the third embodiment. [Figure 10] FIG. 10 is a cross-sectional view of the dust cover according to Modification 1 of the third embodiment. [Figure 11] FIG. 11 is a cross-sectional view of the dust cover according to the fourth embodiment, corresponding to a view excluding the parts corresponding to the attachment member, the first fitting portion, and the second fitting portion from FIG. 5. [Figure 12] FIG. 12 is a cross-sectional view of the dust cover according to Modification 2 of the fourth embodiment, corresponding to a view excluding the parts corresponding to the attachment member, the first fitting portion, and the second fitting portion from FIG. 5. [Figure 13] FIG. 13 is a cross-sectional view of the dust cover according to Modification 3 of the fourth embodiment, corresponding to a view excluding the parts corresponding to the attachment member, the first fitting portion, and the second fitting portion from FIG. 5. [Figure 14] FIG. 14 is a cross-sectional view of the dust cover according to Modification 4 of the fourth embodiment, corresponding to a view excluding the parts corresponding to the attachment member, the first fitting portion, and the second fitting portion from FIG. 5. [Figure 15] FIG. 15 is a cross-sectional view of the dust cover according to Modification 5 of the fourth embodiment, corresponding to a view excluding the parts corresponding to the attachment member, the first fitting portion, and the second fitting portion from FIG. 5. [Figure 16]Figure 16 is a cross-sectional view of a modified example 6 of the fourth embodiment of the dust cover, and corresponds to Figure 5 with the mounting member and the parts corresponding to the first fitting part and the second fitting part removed. [Figure 17] Figure 17 is a cross-sectional view of the dust cover of the fifth embodiment, and corresponds to Figure 5 with the mounting member and the parts corresponding to the first fitting portion and the second fitting portion removed. [Figure 18] Figure 18 is a cross-sectional view of a modified example 7 of the fifth embodiment of the dust cover, and corresponds to Figure 5 with the mounting member and the parts corresponding to the first fitting part and the second fitting part removed. [Figure 19] Figure 19 is a cross-sectional view of a modified example 8 of the fifth embodiment of the dust cover, and corresponds to Figure 5 with the mounting member and the parts corresponding to the first fitting part and the second fitting part removed. [Figure 20] Figure 20 is a schematic diagram that is an enlarged portion of Figure 19. [Modes for carrying out the invention]

[0025] The present invention will now be described in detail with reference to the drawings. However, the present invention is not limited to the embodiments described below. Furthermore, the components in the embodiments below include those easily conceivable by those skilled in the art, those substantially identical, and those within the so-called equivalent range. Moreover, the components disclosed in the embodiments below can be combined as appropriate. In each figure, the passenger compartment side is indicated as IN, and the engine compartment side is indicated as OUT. Also, in each embodiment and modification, identical components are denoted by the same reference numerals, and their description is omitted.

[0026] [First Embodiment] First, a first embodiment of the present invention will be described. Figure 1 is a schematic diagram of the steering device of the first embodiment. Figure 2 is a perspective view of the steering device of the first embodiment.

[0027] As shown in Figure 1, the steering device 80 is connected to a third steering shaft 87, which includes a steering wheel 81, a first steering shaft 82, a steering force assist mechanism 83, a first universal joint 84, a second steering shaft 85, and a second universal joint 86.

[0028] As shown in Figure 1, the first steering shaft 82 comprises an input shaft 82a and an output shaft 82b. One end of the input shaft 82a is connected to the steering wheel 81, and the other end of the input shaft 82a is connected to the output shaft 82b. In addition, one end of the output shaft 82b is connected to the input shaft 82a, and the other end of the output shaft 82b is connected to the first universal joint 84.

[0029] As shown in Figure 1, the second steering shaft 85 connects the first universal joint 84 and the second universal joint 86. One end of the second steering shaft 85 is connected to the first universal joint 84, and the other end is connected to the second universal joint 86. One end of the third steering shaft 87 is connected to the second universal joint 86, and the other end of the third steering shaft 87 is connected to the steering gear 88. As shown in Figure 2, the second steering shaft 85 passes through the dash panel 10. The dash panel 10 is a partition plate that separates the passenger compartment from the engine compartment.

[0030] As shown in Figure 1, the steering gear 88 comprises a pinion 88a and a rack 88b. The pinion 88a is connected to the third steering shaft 87. The rack 88b meshes with the pinion 88a. The steering gear 88 converts the rotational motion transmitted to the pinion 88a into linear motion using the rack 88b. The rack 88b is connected to the tie rod 89. The movement of the rack 88b changes the angle of the wheels.

[0031] As shown in Figure 1, the steering force assist mechanism 83 comprises a reduction gear 92 and an electric motor 93. The reduction gear 92 is, for example, a worm gear reduction gear. The torque generated by the electric motor 93 is transmitted to the worm wheel via a worm inside the reduction gear 92, causing the worm wheel to rotate. The reduction gear 92 increases the torque generated by the electric motor 93 through the worm and worm wheel. The reduction gear 92 then provides auxiliary steering torque to the output shaft 82b. In other words, the steering device 80 is a column assist type. The column assist type is briefly described below. Electric power steering is a system that assists the steering of the steering wheel with a motor without using hydraulics. Examples of electric power steering types include the column assist type, the pinion assist type, and the rack assist type. Of these, the column assist type is, for example, a system in which a motor, reduction gear, and torque sensor are mounted on the column of the steering shaft in the passenger compartment to drive the column shaft.

[0032] As shown in Figure 1, the steering device 80 includes an ECU (Electronic Control Unit) 90, a torque sensor 94, and a vehicle speed sensor 95. The electric motor 93, torque sensor 94, and vehicle speed sensor 95 are electrically connected to the ECU 90. The torque sensor 94 outputs the steering torque transmitted to the input shaft 82a to the ECU 90 via CAN (Controller Area Network) communication. The vehicle speed sensor 95 detects the driving speed (vehicle speed) of the vehicle on which the steering device 80 is mounted. The vehicle speed sensor 95 is mounted on the vehicle body and outputs the vehicle speed to the ECU 90 via CAN communication.

[0033] The ECU 90 controls the operation of the electric motor 93. The ECU 90 acquires signals from the torque sensor 94 and the vehicle speed sensor 95. When the ignition switch 98 is ON, the ECU 90 is supplied with power from the power supply unit 99 (e.g., the vehicle's battery). The ECU 90 calculates an auxiliary steering command value based on the steering torque and vehicle speed. The ECU 90 adjusts the power value supplied to the electric motor 93 based on the auxiliary steering command value. The ECU 90 acquires information on the induced voltage from the electric motor 93 or information output from a resolver or the like provided on the electric motor 93. By controlling the electric motor 93, the force required to operate the steering wheel 81 is reduced.

[0034] Figure 3 is a cross-sectional view of a dust cover mounted on a vehicle. Figure 4 is a front view of the dust cover of the first embodiment. Figure 5 is a cross-sectional view of VV in Figure 4. Figure 6 is a cross-sectional view showing the bellows in Figure 5.

[0035] In the following description, the direction along the central axis Z of the second steering shaft 85 is referred to as the axial direction, the direction perpendicular to the axial direction is referred to as the radial direction, and the direction along the circle centered on the central axis Z is referred to as the circumferential direction. Furthermore, the engine compartment side (OUT) is also referred to as one side of the axial direction, and the passenger compartment side (IN) is also referred to as the other side of the axial direction.

[0036] As shown in Figure 3, the dash panel 10 includes a cylindrical member 101. The inner circumferential surface of the cylindrical member 101 faces the outer circumferential surface 85a of the second steering shaft 85. The second steering shaft 85 may move due to adjustment of the position of the steering wheel 81 or vibrations during driving. For this reason, an annular gap is provided between the inner circumferential surface of the cylindrical member 101 and the outer circumferential surface 85a of the second steering shaft 85. To close this gap, the steering device 80 includes a dust cover 1.

[0037] The dust cover 1 is fitted onto the inner circumferential surface of the cylindrical member 101. The dust cover 1 is fixed to the cylindrical member 101 by a band 100 attached to the outer circumferential surface of the cylindrical member 101. The cylindrical member 101 deforms when tightened by the band 100. For example, the cylindrical member 101 is made of metal. If the cylindrical member 101 is made of metal, it is preferable that the cylindrical member 101 has a slit 102 along the axial direction, as shown in Figure 3. Having a slit 102 in the cylindrical member 101 allows it to deform easily when tightened by the band 100.

[0038] As shown in Figures 4 and 5, the dust cover 1 comprises a bellows 2, a bush 5, and a mounting member 6. The bellows 2, bush 5, and mounting member 6 extend in an annular shape along the circumferential direction about the axis of the central axis Z.

[0039] The mounting member 6 is a member that presses the bellows 2 against the cylindrical member 101 shown in Figure 3. The mounting member 6 is made of, for example, an aluminum alloy. The mounting member 6 may also be made of synthetic resin. As shown in Figure 5, the mounting member 6 comprises a main body portion 61 and a flange portion 62. The main body portion 61 is cylindrical and has an annular groove 611 on its outer circumferential surface. The flange portion 62 protrudes radially outward from the main body portion 61. The mounting member 6 is positioned when the flange portion 62 contacts the cylindrical member 101.

[0040] As shown in Figures 5 and 6, the bellows 2 comprises an annular portion 20, a first flexible portion 21, a first fitting portion 22, a second flexible portion 25, a second fitting portion 26, and a sealing portion 3. The annular portion 20 is located at the radially inward end of the bellows 2. The first flexible portion 21 connects the annular portion 20 and the first fitting portion 22. In a cross-section including the central axis Z, the first flexible portion 21 is approximately U-shaped, convex toward the engine room side (one side in the axial direction).

[0041] The first fitting portion 22 fits into the groove 611 of the mounting member 6. The second flexible portion 25 connects the annular portion 20 and the second fitting portion 26. In a cross-section including the central axis Z, the second flexible portion 25 is roughly U-shaped, convex toward the engine room side (one side in the axial direction). The part of the second flexible portion 25 that is closest to the engine room is the top portion 25a. The second fitting portion 26 fits between the flange portion 62 and the first fitting portion 22. The first flexible portion 21 and the second flexible portion 25 are connected by the annular portion 20. The seal portion 3 will be described in detail later.

[0042] The bush 5 is a bearing that rotatably supports the second steering shaft 85. As shown in Figure 3, the bush 5 is attached to the outer circumferential surface 85a of the second steering shaft 85, which extends axially around the central axis Z, passing through the cylindrical member 101 of the dash panel 10. The bush 5 is a cylindrical member that extends circumferentially around the central axis Z of the second steering shaft 85. As shown in Figure 5, the bush 5 has a main body 50 and flanges 53 and 54. The main body 50 has a cylindrical shape that extends circumferentially around the central axis Z. A lubricant groove 55 is provided on the inner circumferential surface 52 of the main body 50. The lubricant groove 55 extends axially. The lubricant groove 55 extends, for example, along the entire axial length of the bush 5. For example, multiple lubricant grooves 55 are arranged at equal intervals in the circumferential direction. The lubricant groove 55 is filled with grease as a lubricant. This reduces friction between the inner surface 52 of the bush 5 and the outer surface 85a of the second steering shaft 85.

[0043] Furthermore, as shown in Figure 5, a flange 53 protrudes radially outward from one axial end of the main body 50, and a flange 54 protrudes radially outward from the other axial end. The flanges 53 and 54 form a groove 51 on the outer circumference of the bush 5. The annular portion 20 of the bellows fits into the groove 51. Specifically, a radial wall portion 210 protrudes radially outward from one axial end of the annular portion 20, and a radial wall portion 211 protrudes radially outward from the other axial end of the annular portion 20. A bent portion 213 extends from the radial outer end of the radial wall portion 210 toward one side in the axial direction. Also, a bent portion 214 extends from the radial outer end of the radial wall portion 211 toward one side in the axial direction. These annular portion 20, radial wall portion 210, and radial wall portion 211 fit into the groove 51.

[0044] The bush 5 is made of a synthetic resin such as nylon, and its hardness is approximately M100 on the Rockwell hardness scale. The sealing portion 3 of the bellows 2 is made of hard nitrile rubber (NBR), and its hardness is approximately Hs90 on the Shore hardness scale. The parts of the bellows 2 other than the sealing portion 3 (i.e., the annular portion 20, the first flexible portion 21, the first fitting portion 22, the second flexible portion 25, and the second fitting portion 26) are made of soft ethylene propylene rubber (EPDM), and their hardness is approximately Hs60 to 70 on the Shore hardness scale. Thus, comparing the hardness of the bush 5, the sealing portion 3, and the parts of the bellows 2 other than the sealing portion 3, the bush 5 is the hardest, the sealing portion 3 is the next hardest, and the parts of the bellows 2 other than the sealing portion 3 are the softest.

[0045] Next, the seal portion 3 will be described in detail. As shown in Figures 5 and 6, the seal portion 3 includes a first seal portion 31 and a second seal portion 32. The first seal portion 31 is provided between the top portion 25a and the radial wall portion 210 of the second flexible portion 25. Specifically, it is joined to the bent portion 213. The first seal portion 31 includes a lip portion 317. In Figures 5 and 6, which are cross-sections including the central axis Z, the lip portion 317 has a substantially triangular shape that tapers towards the radially inward direction. That is, the lip portion 317 is a substantially triangular shape that tapers from the joining surface 316 located at the radially outward end to the tip 311. The joining surface 316 is joined to the bent portion 213 of the second flexible portion 25. The tip 311 is located radially inward from the outer circumferential surface 85a of the second steering shaft 85.

[0046] The second seal portion 32 includes a lip portion 327. In Figures 5 and 6, the lip portion 327 has a roughly triangular shape that tapers towards the radially inward direction. The joining surface 326 of the lip portion 327 is joined to the first flexible portion 21. Specifically, the radial wall portion 211 has an axial wall portion 212 extending toward the passenger compartment side (the other side in the axial direction). The joining surface 326 of the lip portion 327 is joined to the end of the axial wall portion 212. The tip 321 is located radially inward from the outer circumferential surface 85a of the second steering shaft 85. Regarding the joining of the first seal portion 31 and the bent portion 213, and the joining of the second seal portion 32 and the first flexible portion 21, suitable joining methods include, for example, adhesive bonding and two-color molding.

[0047] As described above, in the first embodiment, the dust cover 1 includes a cylindrical bush 5 attached to the outer circumferential surface 85a of the second steering shaft (steering shaft) 85, which penetrates the cylindrical member 101 of the dash panel 10 and extends in the axial direction of the central axis Z, and extending along the circumferential direction around the axis Z, and a bellows 2 that seals the gap between the cylindrical member 101 and the bush 5. The bellows 2 includes a sealing portion 3 that protrudes toward the outer circumferential surface 85a of the second steering shaft 85 and whose tips 311, 321 abut against the outer circumferential surface 85a, and the bellows 2 is softer than the bush 5.

[0048] As mentioned above, in the dust cover of Patent Document 1, since the sealing member is bonded to the bushing, if the bushing shifts radially relative to the steering shaft, the sealing member may not be able to follow the movement of the bushing, creating a gap between the tip and the outer surface, which could allow dust and other particles to enter the vehicle interior from outside.

[0049] In contrast, in the first embodiment, the seal portion 3 is included in the bellows 2, and the bellows 2 is softer than the bush 5. Therefore, compared to the case where the seal portion 3 is bonded to the bush 5, the seal portion 3 becomes more flexible when the bush 5 is shifted radially relative to the second steering shaft 85, and the contact state between the tips 311 and 321 of the seal portion 3 and the second steering shaft 85 is maintained more reliably. As a result, gaps are less likely to form between the tip 311 of the seal portion 3 and the second steering shaft 85, and the intrusion of dust and other particles from outside the vehicle into the vehicle interior is further suppressed.

[0050] Furthermore, the bellows 2 includes a cylindrical annular portion 20 that extends circumferentially along the outer circumference of the bush 5 and is fixed to the bush 5, a radial wall portion 210 that extends radially outward from the annular portion 20, and a bent portion 213 that bends axially from the radially outer end of the radial wall portion 210. The seal portion 3 protrudes from the bent portion 213 toward the outer circumferential surface 85a of the second steering shaft 85.

[0051] The annular portion 20 is fixed to the bush 5. The bent portion 213 is connected to the annular portion 20 via the radial wall portion 210. Therefore, the bent portion 213 is more flexible than the annular portion 20 and the radial wall portion 210. Accordingly, by providing the seal portion 3 on the bent portion 213, the flexibility of the seal portion 3 is increased, and the contact state between the tips 311 and 321 of the seal portion 3 and the second steering shaft 85 is maintained more reliably.

[0052] [Second Embodiment] Next, a second embodiment of the present invention will be described. Figure 7 is a cross-sectional view of the dust cover of the second embodiment. Figure 8 is a cross-sectional view showing a part of Figure 7. The dust cover 1A of the second embodiment differs from the dust cover 1 of the first embodiment in the seal portion 3A and the bush 5A, so the seal portion 3A and the bush 5A will be described in detail below.

[0053] The bellows 2A includes a sealing portion 3A. As shown in Figures 7 and 8, the sealing portion 3A includes a first sealing portion 31A and a second sealing portion 32A. The first sealing portion 31A is joined to the radial wall portion 210 of the second flexible portion 25. The joining method can be the same as in the first embodiment, and adhesive bonding and two-color molding are applicable. The first sealing portion 31A comprises a base portion 316A and a lip portion 317A. In Figures 7 and 8, which are cross-sections including the central axis Z, the base portion 316A is rectangular. A bent portion 213 extends from the radially outer end of the radial wall portion 210 toward the engine room side (one side in the axial direction). The base portion 316A is joined to the corner of the intersection of the radial wall portion 210 and the bent portion 213. That is, the base portion 316A is joined to both the radial wall portion 210 and the bent portion 213. The joining method can be the same as in the first embodiment, and adhesive bonding and two-color molding are applicable. Furthermore, the end face 316Aa of the radially inner portion of the base portion 316A is located radially inward from the inner circumferential surface 20a of the annular portion 20. The lip portion 317A has a substantially triangular shape that tapers towards the radially inward direction.

[0054] The second seal portion 32A is joined to the radial wall portion 211 of the first flexible portion 21. The second seal portion 32A comprises a base portion 326A and a lip portion 327A. In Figures 7 and 8, which are cross-sections including the central axis Z, the base portion 326A is rectangular in shape. The base portion 326A is joined to the radial wall portion 211. Similar to the first embodiment, bonding and two-color molding can be applied as the joining method. In addition, the end face 326Aa of the radially inner portion of the base portion 326A is located radially inward from the inner circumferential surface 20a of the annular portion 20. The lip portion 327A has a substantially triangular shape that tapers towards the radially inward direction.

[0055] Furthermore, the bush 5A has a cylindrical shape centered on the central axis Z. The bush 5A is fitted to the inner circumference of the annular portion 20. That is, since the end faces 316Aa and 326Aa are located radially inward from the inner circumferential surface 20a of the annular portion 20, a recess is formed between the inner circumferential surface 20a of the annular portion 20, the base portion 316A, and the base portion 326A, with the radially inward opening. The bush 5A is fitted into this recess.

[0056] As described above, in the second embodiment, the first seal portion 31A of the seal portion 3A comprises a base portion 316A joined to both the radial wall portion 210 and the bent portion 213, and a lip portion 317A provided on the axial side of the base portion 316A opposite to the radial wall portion 210 and having a tip 311. The radial inner end (end face 316Aa) of the base portion 316A is located radially inward from the inner circumferential surface 20a of the annular portion 20. The bush 5 abuts against the annular portion 20 and the base portion 316A. The second seal portion 32A of the seal portion 3A comprises a base portion 326A joined to the radial wall portion 211, and a lip portion 327A provided on the axial side of the base portion 326A opposite to the radial wall portion 211 and having a tip 321. The radial inner end (end face 326Aa) of the base portion 326 is located radially inward from the inner circumferential surface 20a of the annular portion 20. The bush 5 abuts against the annular portion 20 and the base portion 326A.

[0057] In this way, since the bush 5 comes into contact with the annular portion 20 and the base portion 316A and base portion 326A, the bellows 2 is less likely to shift position in the axial direction relative to the bush 5.

[0058] [Third Embodiment] Next, a third embodiment of the present invention will be described. Figure 9 is a cross-sectional view of the dust cover of the third embodiment. The dust cover 1B of the third embodiment differs from the dust cover 1 of the first embodiment in its sealing portion 3B, so the sealing portion 3B will be described in detail below.

[0059] The bellows 2B includes a sealing portion 3B. As shown in Figure 9, the sealing portion 3B includes a first sealing portion 31B and a second sealing portion 32. The first sealing portion 31B comprises a base portion 316B and a lip portion 317B. In Figure 9, which is a cross-section including the central axis Z, the base portion 316B is rectangular. The base portion 316B is joined to the radial wall portion 210 of the second flexible portion 25. Similar to the first embodiment, bonding and two-color molding can be applied as the joining method. A bent portion 213 extends from the radially outer end of the radial wall portion 210 toward the engine room side (one side in the axial direction). The bent portion 213 and the base portion 316B are radially opposite each other. The inner circumference of the bent portion 213 and the outer circumference of the base portion 316B are radially separated. The bent portion 213 is located radially outward from the base portion 316B. A gap 120 is provided between the bent portion 213 and the base portion 316B. The lip portion 317B has a roughly triangular shape that tapers towards the radially inward direction. The second seal portion 32 is the same as the second seal portion 32 in Figures 5 and 6.

[0060] As described above, in the third embodiment, the bent portion 213 and the base portion 316B are separated radially and face each other. Therefore, even if the seal portion 3 comes into contact with the second steering shaft 85 and deforms radially, the seal portion 3 is less likely to interfere with the bent portion 213.

[0061] [Example 1] Next, a modified example 1 according to the third embodiment of the present invention will be described. Figure 10 is a cross-sectional view of the dust cover of modified example 1 according to the third embodiment. The dust cover 1C of modified example 1 differs from the dust cover 1A of the second embodiment in the radial position of the sealing portion.

[0062] The bellows 2C includes a sealing portion 3C. As shown in Figure 10, the sealing portion 3C includes a first sealing portion 31C and a second sealing portion 32C. The first sealing portion 31C comprises a base portion 316C and a lip portion 317C. In Figure 10, which is a cross-section including the central axis Z, the base portion 316C is rectangular. The base portion 316C is joined to the radial wall portion 210 of the second flexible portion 25. The joining method can be adhesive and two-color molding, as in the first embodiment. The bent portion 213 and the base portion 316C are radially opposite each other. The inner circumference of the bent portion 213 and the outer circumference of the base portion 316C are radially separated. The bent portion 213 is located radially outward from the base portion 316C. A gap 120 is provided between the bent portion 213 and the base portion 316C. The end face 316Ca of the radially inner portion of the base portion 316C is located radially inward from the inner circumferential surface 20a of the annular portion 20. The lip portion 317C has a roughly triangular shape that tapers towards the radially inward direction.

[0063] The second seal portion 32C is joined to the radial wall portion 211 of the first flexible portion 21. Similar to the first embodiment, bonding and two-color molding are applicable for this joining method. The second seal portion 32C comprises a base portion 326C and a lip portion 327C. In Figure 10, which is a cross-section including the central axis Z, the base portion 326C is rectangular. The base portion 326C is joined to the radial wall portion 211. Furthermore, the end face 326Ca of the radially inner portion of the base portion 326C is located radially inward from the inner circumferential surface 20a of the annular portion 20. The lip portion 327C has a substantially triangular shape that tapers towards the radially inward direction.

[0064] As explained above, in the modified example 1 as well, the bent portion 213 and the base portion 316C are separated radially and face each other. Therefore, even if the seal portion 3 comes into contact with the second steering shaft 85 and deforms radially, the seal portion 3 is less likely to interfere with the bent portion 213.

[0065] [Fourth Embodiment] Next, a fourth embodiment of the present invention will be described. Figure 11 is a cross-sectional view of the dust cover of the fourth embodiment, and corresponds to Figure 5 with the mounting member 6 and the parts corresponding to the first fitting portion 22 and the second fitting portion 26 removed. The dust cover 1D of the fourth embodiment differs from the dust cover 1B of the third embodiment in that the first sealing portion and the second sealing portion are connected.

[0066] The bellows 2D includes a seal portion 3D. As shown in Figure 11, the seal portion 3D includes a first seal portion 31D, a second seal portion 32D, and a cylindrical portion 30. The first seal portion 31D and the second seal portion 32D are connected axially via the cylindrical portion 30. The cylindrical portion 30 extends circumferentially along the outer circumference of the bush 5A (see Figure 10). The first seal portion 31D is provided on one axial side of the cylindrical portion 30, and the tip 311 on that axial side contacts the outer circumferential surface 85a of the second steering shaft 85. The second seal portion 32D is provided on the other axial side of the cylindrical portion 30, and the tip 321 on that other axial side contacts the outer circumferential surface 85a of the second steering shaft 85.

[0067] The first seal portion 31D comprises a base portion 316D, a lip portion 317D, and a protruding portion 313. The second seal portion 32D comprises a base portion 326D, a lip portion 327D, and a protruding portion 313. The outer circumference 314 of the cylindrical portion 30 is located radially inward from the outer circumferences of the base portions 316D and 326D. Therefore, a recess is formed on the outer circumference of the seal portion 3D by the base portions 316D and 326D and the cylindrical portion 30, and the annular portion 20 is joined to the cylindrical portion 30 with the annular portion 20 fitted into the recess. The joining method can be the same as in the first embodiment, and adhesive bonding and two-color molding are applicable.

[0068] As shown in Figure 11, the inner diameter of the tip 311 of the first seal portion 31D and the inner diameter of the tip 321 of the second seal portion 32D are defined as inner diameter A. The inner diameter of the bush 5A is defined as inner diameter B. The inner diameter of the inner end of the protrusion 313 is defined as inner diameter C. Inner diameter B is larger than inner diameter A, and inner diameter C is larger than inner diameter B. That is, the inner diameters increase in the order of inner diameter A, inner diameter B, and inner diameter C. Note that in Figures 12 to 19, inner diameters A, B, and C are formed in a similar order of size.

[0069] The radial inner end of the protrusion 313 is located radially inward from the inner circumferential surface of the cylindrical portion 30. Therefore, a recess is formed between the protrusion 313 of the first seal portion 31D, the cylindrical portion 30, and the protrusion 313 of the second seal portion 32D, with the radial inner side being open. The bush 5A is fitted into this recess.

[0070] Furthermore, when the second steering shaft 85 is inserted into the inner circumference of the bush 5, if the central axis Z of the second steering shaft 85 coincides with the axis of the bush 5, the tips 311 and 321 of the seal portion 3D come into contact with the outer circumferential surface 85a of the second steering shaft 85, causing the seal portion 3D to elastically deform.

[0071] When the second steering shaft 85 is inserted into the inner circumference of the bush 5, if the central axis Z of the second steering shaft 85 and the axis of the bush 5 become misaligned, the bush 5 will move in accordance with the second steering shaft 85. As a result, the tips 311 and 321 of the seal portion 3D will come into contact with the outer circumferential surface 85a of the second steering shaft 85, thus preventing a gap from forming between the tips 311 and 321 of the seal portion 3D and the outer circumferential surface 85a of the second steering shaft 85.

[0072] The inner circumferential end of the protrusion 313 does not come into contact with the outer circumferential surface 85a of the second steering shaft 85. As described above, the bush 5A is fitted into the recess formed by the protrusion 313.

[0073] As described above, in the fourth embodiment, the seal portion 3D comprises a cylindrical portion 30 that extends circumferentially along the outer circumference of the bush 5 and is assembled to the bush 5; a first seal portion 31D provided on one axial side of the cylindrical portion 30, with its tip 311 in contact with the outer circumferential surface 85a of the second steering shaft 85; and a second seal portion 32D provided on the other axial side of the cylindrical portion 30, with its tip 321 in contact with the outer circumferential surface 85a of the second steering shaft 85.

[0074] In this way, since the first seal portion 31D and the second seal portion 32D are connected via the cylindrical portion 30, the molding of the seal portion 3D becomes easier than when the first seal portion and the second seal portion are not connected.

[0075] Furthermore, the bellows 2D includes a cylindrical annular portion 20 that extends along the outer circumference of the cylindrical portion 30 and is joined to the outer circumference of the cylindrical portion 30. In this way, the sealing portion 3D is formed by joining the cylindrical portion 30 to the annular portion 20, making the molding work of the sealing portion 3D easier.

[0076] [Differentiation 2] Next, a modified example 2 according to the fourth embodiment of the present invention will be described. Figure 12 is a cross-sectional view of the dust cover of modified example 2 according to the fourth embodiment, and corresponds to a view obtained by removing the mounting member 6 and the parts corresponding to the first fitting portion 22 and the second fitting portion 26 from Figure 5. The dust cover 1E of modified example 2 differs from the dust cover 1D of the fourth embodiment in that it has an uneven coupling structure.

[0077] The bellows 2E includes a sealing portion 3E. As shown in Figure 12, the sealing portion 3E includes a first sealing portion 31E, a second sealing portion 32E, and a cylindrical portion 30. The first sealing portion 31E and the second sealing portion 32E are connected axially via the cylindrical portion 30.

[0078] The first seal portion 31E comprises a base portion 316D, a lip portion 317D, and a protruding portion 313. The second seal portion 32E comprises a base portion 326D, a lip portion 327D, and a protruding portion 313. Note that the first seal portion 31E is identical to the first seal portion 31D, and the second seal portion 32E is identical to the second seal portion 32D. The cylindrical portion 30 has a convex portion 130 that protrudes radially outward. The convex portion 130 comprises a base portion 131 and a wide portion (tip portion) 132. The axial length of the wide portion 132 is greater than the axial length of the base portion 131. The wide portion 132 protrudes axially on both sides at the radially outer end of the base portion 131. In addition, the annular portion 20 is provided with a recess 140. The recess 140 fits into the convex portion 130. The recess 140 comprises a narrow portion 141 and a wide portion 142. The base portion 131 is fitted into the narrow portion 141, and the wide portion 132 is fitted into the wide portion 142. The recess 140 and the protrusion 130 are joined together with the protrusion 130 fitted into the recess 140. The joining method can be the two-color molding method described in the first embodiment. In this case, the annular portion 20 and the cylindrical portion 30 are two-color molded products.

[0079] As explained above, in modified example 2, one of the annular portion 20 and the cylindrical portion 30 (the cylindrical portion 30) has a protrusion 130, and the other (the annular portion 20) has a recess 140 that fits into the protrusion 130. Therefore, the bonding strength between the annular portion 20 and the cylindrical portion 30 is increased.

[0080] Furthermore, the protrusion 130 comprises a base portion 131 and a wide portion 132 (tip portion) provided at the tip of the base portion 131, and the axial length of the wide portion 132 is greater than the axial length of the base portion 131. In this way, the wide portion 132 is wider than the base portion 131, and the wide portion 132 catches on the recess 140, thus increasing the bonding strength between the annular portion 20 and the cylindrical portion 30.

[0081] Furthermore, since the annular portion 20 and the cylindrical portion 30 are two-color molded products, the molding of the convex portion 130 and the concave portion 140 becomes easier.

[0082] [Difference 3] Next, a modified example 3 according to the fourth embodiment of the present invention will be described. Figure 13 is a cross-sectional view of the dust cover of modified example 3 according to the fourth embodiment, and corresponds to a view of Figure 5 with the mounting member 6 and the parts corresponding to the first fitting portion 22 and the second fitting portion 26 removed. The dust cover 1F of modified example 3 differs from the dust cover 1E of modified example 2 in its concave and concave coupling configuration.

[0083] The bellows 2F includes a sealing portion 3F. As shown in Figure 13, the sealing portion 3F includes a first sealing portion 31F, a second sealing portion 32F, and a cylindrical portion 30. The first sealing portion 31F and the second sealing portion 32F are connected axially via the cylindrical portion 30.

[0084] The first seal portion 31F comprises a base portion 316F, a lip portion 317F, and a protruding portion 313. The second seal portion 32F comprises a base portion 326F, a lip portion 327F, and a protruding portion 313. The outer circumference of the cylindrical portion 30 is flush with the outer circumferences of the base portions 316F and 326F. That is, the outer circumference of the cylindrical portion 30 is at the same radial position as the outer circumferences of the base portions 316F and 326F.

[0085] Furthermore, the annular portion 20 has a protrusion 130F that projects radially inward. The protrusion 130F comprises a base portion 131F and a wide portion 132F. The axial length of the wide portion 132F is greater than the axial length of the base portion 131F. The wide portion 132F protrudes axially on both sides at the radially inward end of the base portion 131F. The cylindrical portion 30 is provided with a recess 140F. The recess 140F fits into the protrusion 130F. The recess 140F comprises a narrow portion 141F and a wide portion 142F. The base portion 131F fits into the narrow portion 141F, and the wide portion 132F fits into the wide portion 142F. The recess 140F and the protrusion 130F are joined when the protrusion 130F is fitted into the recess 140F. The joining method can be the two-color molding method described in the first embodiment.

[0086] As explained above, in Modified Example 3, one of the annular portion 20 and the cylindrical portion 30 (the annular portion 20) has a protrusion 130F, and the other (the cylindrical portion 30) has a recess 140F that fits into the protrusion 130F. Therefore, the bonding strength between the annular portion 20 and the cylindrical portion 30 is increased.

[0087] [Differentiation Example 4] Next, a modified example 4 according to the fourth embodiment of the present invention will be described. Figure 14 is a cross-sectional view of the dust cover of modified example 4 according to the fourth embodiment, and corresponds to a view of Figure 5 with the mounting member 6 and the parts corresponding to the first fitting portion 22 and the second fitting portion 26 removed. The dust cover 1G of modified example 4 differs from the dust cover 1E of modified example 2 in the configuration of the interlocking connection between the annular portion 20 and the cylindrical portion 30.

[0088] The bellows 2G includes a sealing portion 3G. As shown in Figure 14, the sealing portion 3G includes a first sealing portion 31G, a second sealing portion 32G, and a cylindrical portion 30. The first sealing portion 31G and the second sealing portion 32G are connected axially via the cylindrical portion 30.

[0089] The first seal portion 31G comprises a base portion 316G, a lip portion 317G, and a protruding portion 313. The second seal portion 32G comprises a base portion 326G, a lip portion 327G, and a protruding portion 313. Furthermore, the cylindrical portion 30 has a convex portion 130G that protrudes radially outward. As shown in Figure 14, which shows a cross-section including the central axis Z, the convex portion 130G is rectangular in shape. A recess 140G is provided on the radially inward side of the annular portion 20. The recess 140G also has a rectangular cross-section. The convex portion 130G fits into the recess 140G. The recess 140G and the convex portion 130G are joined together when the convex portion 130G is fitted into the recess 140G. The joining method can be the same as in the first embodiment, and adhesive bonding and two-color molding are applicable.

[0090] As explained above, in Modification 4, one of the annular portion 20 and the cylindrical portion 30 (the cylindrical portion 30) has a protrusion 130G, and the other (the annular portion 20) has a recess 140G that fits into the protrusion 130G. Therefore, the bonding strength between the annular portion 20 and the cylindrical portion 30 is increased.

[0091] [Difference 5] Next, a modified example 5 according to the fourth embodiment of the present invention will be described. Figure 15 is a cross-sectional view of the dust cover of modified example 5 according to the fourth embodiment, and corresponds to a view of Figure 5 with the mounting member 6 and the parts corresponding to the first fitting portion 22 and the second fitting portion 26 removed. The dust cover 1H of modified example 5 differs from the dust cover 1F of modified example 3 in the configuration of the interlocking connection between the annular portion 20 and the cylindrical portion 30.

[0092] The bellows 2H includes a sealing portion 3H. As shown in Figure 15, the sealing portion 3H includes a first sealing portion 31H, a second sealing portion 32H, and a cylindrical portion 30. The first sealing portion 31H and the second sealing portion 32H are connected axially via the cylindrical portion 30.

[0093] The first seal portion 31H comprises a base portion 316H, a lip portion 317H, and a protruding portion 313. The second seal portion 32H comprises a base portion 326H, a lip portion 327H, and a protruding portion 313. The outer circumference of the cylindrical portion 30 is flush with the outer circumferences of the base portions 316H and 326H. That is, the outer circumference of the cylindrical portion 30 is at the same radial position as the outer circumferences of the base portions 316H and 326H.

[0094] Furthermore, the annular portion 20 has a protrusion 130H that projects radially inward. As shown in Figure 15, which shows a cross-section including the central axis Z, the protrusion 130H is rectangular in shape. The cylindrical portion 30 is provided with a recess 140H. The recess 140H has a rectangular cross-section. The protrusion 130H fits into the recess 140H. The recess 140H and the protrusion 130H are joined together when the protrusion 130H is fitted into the recess 140H. As with the first embodiment, bonding and two-color molding can be applied as methods for joining them.

[0095] As explained above, in modified example 5, one of the annular portion 20 and the cylindrical portion 30 (the annular portion 20) has a protrusion 130H, and the other (the cylindrical portion 30) has a recess 140H that fits into the protrusion 130H. Therefore, the bonding strength between the annular portion 20 and the cylindrical portion 30 is increased.

[0096] [Modification 6] Next, a modified example 6 according to the fourth embodiment of the present invention will be described. Figure 16 is a cross-sectional view of the dust cover of modified example 6 according to the fourth embodiment, and corresponds to a view obtained by removing the mounting member 6 and the parts corresponding to the first fitting part 22 and the second fitting part 26 from Figure 5. The dust cover 1I of modified example 6 differs from the dust cover 1F of modified example 3 in the configuration of the interlocking connection between the annular part 20 and the cylindrical part 30.

[0097] The bellows 2I includes a sealing portion 3I. As shown in Figure 16, the sealing portion 3I includes a first sealing portion 31I, a second sealing portion 32I, and a cylindrical portion 30. The first sealing portion 31I and the second sealing portion 32I are connected axially via the cylindrical portion 30.

[0098] The first seal portion 31I comprises a base portion 316I, a lip portion 317I, and a protruding portion 313. The second seal portion 32I comprises a base portion 326I, a lip portion 327I, and a protruding portion 313. The outer circumference 30a of the cylindrical portion 30 is flush with the outer circumferences of the base portions 316I and 326I. That is, the outer circumference 30a of the cylindrical portion 30 is at the same radial position as the outer circumferences of the base portions 316I and 326I.

[0099] Furthermore, the outer circumference 30a of the cylindrical portion 30 is a cylindrical surface extending in the circumferential direction around the central axis Z. The outer circumference 30a of the cylindrical portion 30 is joined to the inner circumference of the annular portion 20 in a state of contact. The bonding method described in the first embodiment can be applied to this joining.

[0100] As described above, in modified example 6, the seal portion 3I is formed by joining the cylindrical portion 30 to the annular portion 20, making the molding of the seal portion 3I easier. In particular, since the outer circumference 30a of the cylindrical portion 30 is flush with the outer circumference of the base portions 316I and 326I, the annular portion 20 is less likely to interfere with the outer circumference of the seal portion 3I during the molding of the seal portion 3I.

[0101] [Fifth Embodiment] Next, a fifth embodiment of the present invention will be described. Figure 17 is a cross-sectional view of the dust cover of the fifth embodiment, and corresponds to Figure 5 with the mounting member 6 and the parts corresponding to the first fitting portion 22 and the second fitting portion 26 removed. The dust cover 1J of the fifth embodiment differs from the dust cover 1I of modified example 6 in the shape of the ends of the first flexible portion 21 and the second flexible portion 25 in the bellows 2J.

[0102] The bellows 2J comprises a first flexible portion 21 and a second flexible portion 25. In the first to fourth embodiments, the radially inner end of the first flexible portion 21 and the radially inner end of the second flexible portion 25 are connected axially via an annular portion 20. In contrast, in the bellows 2J of the fifth embodiment, the radially inner end of the first flexible portion 21 and the radially inner end of the second flexible portion 25 are not connected. That is, the bellows 2J comprises a first radial wall portion 215 extending radially outward from one side in the axial direction and a second radial wall portion 216 extending radially outward from the other side in the axial direction. In other words, the first radial wall portion 215 corresponds to the radial wall portion 210 described above, and the second radial wall portion 216 corresponds to the radial wall portion 211 described above.

[0103] Furthermore, the bellows 2J includes a sealing portion 3J. As shown in Figure 17, the sealing portion 3J includes a first sealing portion 31J, a second sealing portion 32J, and a cylindrical portion 30. The first sealing portion 31J and the second sealing portion 32J are connected axially via the cylindrical portion 30.

[0104] The first seal portion 31J comprises a base portion 316J, a lip portion 317J, and a protruding portion 313. The second seal portion 32J comprises a base portion 326J, a lip portion 327J, and a protruding portion 313. The outer circumference 30a of the cylindrical portion 30 is flush with the outer circumferences of the base portions 316J and 326J. That is, the outer circumference 30a of the cylindrical portion 30 is at the same radial position as the outer circumferences of the base portions 316J and 326J. The outer circumference 30a of the cylindrical portion 30 is a cylindrical surface extending in the circumferential direction around the axis of the central axis Z.

[0105] Furthermore, the radially inner tip surface 210a of the first radial wall portion 215 and the radially inner tip surface 211a of the second radial wall portion 216 are flat surfaces. The radially inner tip surface 210a of the first radial wall portion 215 and the radially inner tip surface 211a of the second radial wall portion 216 are joined in a state where they abut against the outer circumference 30a of the cylindrical portion 30. The bonding method described in the first embodiment can be applied to this joining.

[0106] As described above, in the fifth embodiment, the bellows 2 comprises a first radial wall portion 215 extending radially outward from one axial side of the cylindrical portion 30, and a second radial wall portion 216 extending radially outward from the other axial side of the cylindrical portion 30.

[0107] Furthermore, in the fourth embodiment, the radial wall portion on one axial side and the axial wall portion on the other side are connected via an annular portion, but in the fifth embodiment, the first radial wall portion 215 and the second radial wall portion 216 are not connected. Therefore, since the first radial wall portion 215 and the second radial wall portion 216 can each be joined to the cylindrical portion 30, the joining work becomes easier.

[0108] [Difference 7] Next, a modified example 7 according to the fifth embodiment of the present invention will be described. Figure 18 is a cross-sectional view of the dust cover of modified example 7 according to the fifth embodiment, and corresponds to a view of Figure 5 with the mounting member 6 and the parts corresponding to the first fitting portion 22 and the second fitting portion 26 removed. The dust cover 1K of modified example 7 differs from the dust cover 1J of the fifth embodiment in the shape of the ends of the first radial wall portion 215 and the second radial wall portion 216 in the bellows 2K.

[0109] In the bellows 2K, the radially inner end of the first flexible portion 21 and the radially inner end of the second flexible portion 25 are not connected.

[0110] Furthermore, the bellows 2K includes a sealing portion 3K. As shown in Figure 18, the sealing portion 3K includes a first sealing portion 31K, a second sealing portion 32K, and a cylindrical portion 30. The first sealing portion 31K and the second sealing portion 32K are connected axially via the cylindrical portion 30.

[0111] The first seal portion 31K comprises a base portion 316K, a lip portion 317K, and a protruding portion 313. The second seal portion 32K comprises a base portion 326K, a lip portion 327K, and a protruding portion 313. The cylindrical portion 30 has a protruding portion 30b on its outer circumference. The protruding portion 30b is located in the axial center of the cylindrical portion 30. The protruding portion 30b protrudes radially outward.

[0112] Furthermore, protrusions 130K are provided at the radially inner end 210b of the first radial wall portion 215 and at the radially inner end 211b of the second radial wall portion 216. The protrusions 130K of the first radial wall portion 215 are provided projecting toward the passenger compartment side. The protrusions 130K of the second radial wall portion 216 are provided projecting toward the engine compartment side. That is, the protrusions 130K of the radially inner end 210b and the protrusions 130K of the radially inner end 211b project in directions opposite to each other. In addition, recesses 140K are provided in the protrusions 30b. The recesses 140K are provided on one side and the other side in the axial direction. The protrusions 130K of the radially inner end 210b are fitted into the recesses 140K on one side in the axial direction. The protrusion 130K of the radially inner end 211b is fitted into the recess 140K on the other axial side. The recess 140K and the protrusion 130K are joined together with the protrusion 130K fitted into the recess 140K. Two-color molding, as described in the first embodiment, can be applied to this joining method. In this case, the first radial wall portion 215, the second radial wall portion 216, and the cylindrical portion 30 are two-color molded products.

[0113] As described above, in modified example 7, the radial inner ends 210b and 211b of the first radial wall portion 215 and the second radial wall portion 216, respectively, have protrusions 130K that project in the axial direction, and the cylindrical portion 30 has recesses 140K that fit into the protrusions 130K. Therefore, the bonding strength between the radial inner end 210b of the first radial wall portion 215 and the cylindrical portion 30, and the bonding strength between the radial inner end 211b of the second radial wall portion 216 and the cylindrical portion 30 are increased.

[0114] [Differentiation 8] Next, a modified example 8 according to the fifth embodiment of the present invention will be described. Figure 19 is a cross-sectional view of the dust cover of modified example 8 according to the fifth embodiment, and corresponds to a view obtained by removing the mounting member 6 and the parts corresponding to the first fitting part 22 and the second fitting part 26 from Figure 5. Figure 20 is a schematic diagram that is an enlargement of a part of Figure 19. Modified example 8 differs from the fourth embodiment shown in Figure 11 in the shape of the ends of the first flexible part 21 and the second flexible part 25 in the bellows 2L.

[0115] In the bellows 2L, the radially inner end of the first flexible portion 21 and the radially inner end of the second flexible portion 25 are not connected.

[0116] Furthermore, the bellows 2L includes a sealing portion 3L. As shown in Figure 19, the sealing portion 3L includes a first sealing portion 31L, a second sealing portion 32L, and a cylindrical portion 30. The first sealing portion 31L comprises a base portion 316L, a lip portion 317L, and a protruding portion 313. The second sealing portion 32L comprises a base portion 326L, a lip portion 327L, and a protruding portion 313. The first sealing portion 31L and the second sealing portion 32L are connected axially via the cylindrical portion 30.

[0117] Furthermore, joint portions 130L are provided at the radially inner end 210b of the first radial wall portion 215 and at the radially inner end 211b of the second radial wall portion 216. The axial distance of the joint portion 130L increases as it moves radially inward. As shown in Figure 20, the joint portion 130L on one side in the axial direction comprises a joint portion body 130L1 and a joint portion tip 130L2 in a cross-section including the central axis Z. The joint portion body 130L1 has a rectangular cross-section. The inner circumferential surface 130L1a of the joint portion body 130L1 is bonded to the outer circumference 30a of the cylindrical portion 30. The side surface 130L1b of the joint portion body 130L1 is bonded to the base portion 316L of the first seal portion 31L. The joint portion tip 130L2 has a substantially triangular cross-section. Specifically, the joint portion 130L on one side in the axial direction has a roughly triangular joint tip 130L2 that protrudes toward the other side in the axial direction, and the joint tip 130L2 is bonded to the outer circumference 30a of the cylindrical portion 30.

[0118] The joint portion 130L provided on the other side in the axial direction also comprises a joint portion body with a rectangular cross-section and a joint portion tip with a roughly triangular cross-section, with the joint portion tip protruding toward one side in the axial direction. The joint portion body is bonded to the base portion 326L of the second seal portion 32L and the outer circumference 30a of the cylindrical portion 30, and the joint portion tip is bonded to the outer circumference 30a of the cylindrical portion 30.

[0119] As described above, in modified example 8, the radially inner ends 210b and 211b of the first radial wall portion 215 and the second radial wall portion 216, respectively, have a joint portion 130L that is joined to the outer circumference of the cylindrical portion 30, and the axial distance increases as it moves radially inward. In this way, the axial distance of the joint portion 130L joined to the outer circumference of the cylindrical portion 30 is greater than the axial distance of the other parts, so the joining area with the cylindrical portion 30 is larger than in the fifth embodiment (see Figure 17) which does not have a joint portion 130L, and as a result the joining strength between the first radial wall portion 215 and the second radial wall portion 216 and the cylindrical portion 30 is greater. [Explanation of symbols]

[0120] 1, 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1I, 1J, 1K Dust cover 2, 2A, 2B, 2C, 2D, 2E, 2F, 2G, 2H, 2I, 2J, 2K Bellows 3, 3A, 3B, 3C, 3D, 3E, 3F, 3G, 3H, 3I, 3J, 3K Seal part 5, 5A bushing 6. Mounting components 10. Dashboard 20 Ring section 20a Inner surface 21 First flexible part 22 First fitting section 25 Second flexible part 25a top 26 Second mating section 30 Cylinder part 30a Outer perimeter 30b Protrusion 31, 31A, 31B, 31C, 31D, 31E, 31F, 31G, 31H, 31I, 31J, 31K First seal section 32, 32A, 32C, 32D, 32E, 32F, 32G, 32H, 32I, 32J, 32K Second seal section 50 Main body 51. Groove 52 Inner surface 53, 54 Flange 55 Lubricant groove 61 Main body 62 Flange section 80 Steering system 81 Steering Wheel 82. First steering shaft 82a Input axis 82b Output shaft 83 Steering force assist mechanism 84. First Universal Joint 85. Second steering shaft (steering shaft) 85a Outer surface 86. Second Universal Joint 87. Third steering shaft 88 Steering gear 88a pinion 88b rack 89 Tie Rod 90 ECU 92 Reducer 93 Electric motor 94 Torque Sensor 95 Vehicle speed sensor 98 Ignition Switch 99 Power supply 100 bands 101 Cylindrical member 102 Slits 120 gap 130, 130F, 130G, 130H, 130K protrusions 130L joint 130L1 Joint Body 130L1a Inner surface 130L1b side 130L2 Joint tip 131, 131F base 132, 132F Wide section (tip section) 140, 140F, 140G, 140H, 140K recess 141, 141F narrow section 142, 142F Wide section 210 Radial wall section 210a Tip surface 210b Radial inner end 211 Radial wall section 211a Tip surface 211b Radial inner end 212 Axial wall 213, 214 Bending section 215 First radial wall section 216 Second radial wall 311 Tip 313 Protrusion 316 Joint surface 316A, 316B, 316C, 316D, 316F, 316G, 316H, 316I, 316J, 316K, 316L Base section 317, 317A, 317B, 317C, 317D, 317F, 317G, 317H, 317I, 317J, 317K, 317L Lip part 316Aa, 316Ca End face 321 Tip 326 Joint surface 326A, 326C, 326D, 326F, 326G, 326H, 326I, 326J, 326K, 326L Base part 327, 327A, 327C, 327D, 327F, 327G, 327H, 327I, 327J, 327K, 327L Lip part 326Aa, 326Ca End face 611 Groove Z Central axis

Claims

1. A cylindrical bush attached to the outer surface of a steering shaft that penetrates a cylindrical member of a dash panel and extends in the axial direction of the central axis, and extending along the circumferential direction about the axis of the central axis, A bellows that seals the gap between the cylindrical member and the bush, Equipped with, The bellows includes a sealing portion that protrudes toward the outer circumferential surface of the steering shaft and whose tip abuts against the outer circumferential surface, The bellows is softer than the bushing. The bellows comprises a cylindrical annular portion extending circumferentially along the outer circumference of the bush, a radial wall portion extending radially outward from the annular portion, and a bent portion bending axially from the radially outer end of the radial wall portion. The aforementioned sealing portion is From the radial wall portion, protruding toward the outer circumferential surface of the steering shaft, The aforementioned sealing portion is A base portion joined to the radial wall portion, The base portion comprises a lip portion provided on the opposite side in the axial direction from the radial wall portion and having the tip portion, The radial inner end of the base portion is located radially inward from the inner circumferential surface of the annular portion. The aforementioned bush, The annular portion and the base portion abut against each other, Dust cover.

2. The bent portion and the base portion are separated radially and face each other. The dust cover according to claim 1.

3. A cylindrical bush attached to the outer surface of a steering shaft that penetrates a cylindrical member of the dash panel and extends in the axial direction of the central axis, and extending along the circumferential direction about the axis of the central axis, A bellows that seals the gap between the cylindrical member and the bush, Equipped with, The bellows includes a sealing portion that protrudes toward the outer circumferential surface of the steering shaft and whose tip abuts against the outer circumferential surface, The bellows is softer than the bushing. The aforementioned sealing portion is A cylindrical portion extending circumferentially along the outer circumference of the bush, A first seal portion is provided on one side in the axial direction of the cylindrical portion, and the tip on the one side in the axial direction is in contact with the outer circumferential surface of the steering shaft, The device comprises a second seal portion provided on the other axial side of the cylindrical portion, the tip of which on the other axial side contacts the outer circumferential surface of the steering shaft, Dust cover.

4. The bellows comprises a cylindrical annular portion that extends along the outer circumference of the cylindrical portion and is joined to the outer circumference of the cylindrical portion. The dust cover according to claim 3.

5. One of the annular portion and the cylindrical portion has a protrusion, and the other has a recess that fits into the protrusion. The dust cover according to claim 4.

6. The aforementioned protrusion comprises a base portion and a tip portion provided at the tip of the base portion. The axial length of the tip portion is greater than the axial length of the base portion. The dust cover according to claim 5.

7. The annular portion and the cylindrical portion are two-color molded products. The dust cover according to claim 5 or 6.

8. The bellows comprises a first radial wall portion extending radially outward from one axial side of the cylindrical portion, and a second radial wall portion extending radially outward from the other axial side of the outer circumference of the cylindrical portion. The dust cover according to claim 3.

9. The radially inner ends of the first radial wall portion and the second radial wall portion each have a protrusion that projects in the axial direction. The cylindrical portion has a recess that fits into the convex portion. The dust cover according to claim 8.

10. The radially inner ends of the first radial wall and the second radial wall each have a joint that is joined to the outer circumference of the cylindrical portion, with the axial distance increasing as it moves radially inward. The dust cover according to claim 8.

11. The aforementioned joint is bonded to the outer circumference of the cylindrical portion. The dust cover according to claim 10.

Images