Dust cover

Abstract

To provide a dust cover that can be manufactured with fewer work man-hours.SOLUTION: A dust cover includes: an annular bush mounted on an outer peripheral surface of a steering shaft; an annular seal member provided on a radially outside of the bush; and a bellows. The seal member has: a cylindrical portion held between an outer peripheral surface of the bush and a radially inside end of the bellows; a first seal portion provided integrally with the cylindrical portion on one side in an axial direction of the cylindrical portion; and a second seal portion provided integrally with the cylindrical portion on the other side in the axial direction of the cylindrical portion.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 technology]

[0002] A dust cover is sometimes provided in the gap between a steering shaft of a vehicle and a penetration part of a dash panel (see, for example, Patent Document 1). The dust cover described in Patent Document 1 includes a bellows, a cylindrical bushing attached to the steering shaft, and two seal members vulcanization-bonded to one side and the other side of the bushing in the axial direction. Thus, in Patent Document 1, two seal members are provided, and the two seal members are vulcanization-bonded to the bushing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-6268 Summary of the Invention [Problem to be solved by the invention]

[0004] However, if the seal member is separate from the bushing, the seal member needs to be bonded to the bushing, which increases the number of steps required to manufacture the dust cover. For example, the vulcanization bonding process for vulcanizing the seal member includes the steps of applying an adhesive to the bushing, drying the adhesive, and vulcanizing the seal member to the bushing.

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a dust cover that can be manufactured with fewer work steps. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, a dust cover of one embodiment of the present disclosure includes: an annular bushing attached to an outer peripheral surface of a steering shaft that extends axially of a central axis through a cylindrical member of a dash panel; a sealing member provided radially outside the bushing and extending circumferentially around the central axis; and a bellows that closes a gap between the cylindrical member and the sealing member, wherein the sealing member has: a cylindrical portion sandwiched between the outer peripheral surface of the bushing and a radially inner end of the bellows; a first sealing portion that is integral with the cylindrical portion on one side of the axial direction of the cylindrical portion and has a tip end on the one axial side that contacts the outer peripheral surface of the steering shaft; and a second sealing portion that is integral with the cylindrical portion on the other axial side of the cylindrical portion and has a tip end on the other axial side that contacts the outer peripheral surface of the steering shaft.

[0007] As described above, in the dust cover of Patent Document 1, if the seal member is separate from the bush, the seal member needs to be adhered to the bush, which increases the number of steps required to manufacture the dust cover.

[0008] In contrast, in the present disclosure, the first seal portion and the second seal portion are integrated via a cylindrical portion to form a single seal member. Therefore, compared to Patent Document 1, the present disclosure can provide a dust cover that can be manufactured with fewer man-hours. In Patent Document 1, when multiple seal members are simultaneously vulcanized and bonded, the mold structure becomes complex, increasing mold costs. However, in the present disclosure, the vulcanization bonding process is eliminated, reducing mold costs. Furthermore, when the first seal portion and the second seal portion are integrated, the first seal portion and the second seal portion are more securely fixed to the bushing than when the first seal portion and the second seal portion are separate. Therefore, the first seal portion and the second seal portion are less likely to come off the bushing, enabling a reliable seal with the steering shaft. Furthermore, because the first seal portion and the second seal portion are integrated, the axial positions of the first seal portion and the second seal portion are stable, resulting in a stable seal with the steering shaft.

[0009] In a preferred embodiment of the dust cover, the seal member is harder than the bellows. The first seal portion and the second seal portion contact the outer peripheral surface of the steering shaft, so when the steering shaft rotates, the first seal portion and the second seal portion rub against the steering shaft. However, when the seal member is harder than the bellows, abnormal noise caused by the seal member rubbing against the steering shaft is reduced more than when the seal member is softer than the bellows.

[0010] In a preferred embodiment of the dust cover, a recess is provided on the outer periphery of the sealing member, into which the radially inner end of the bellows fits, and the bottom surface of the recess is the outer periphery of the cylindrical portion. In this way, the radially inner end of the bellows fits into the recess on the outer periphery of the sealing member, further easing the work of assembling the bellows to the sealing member.

[0011] In a preferred embodiment of the dust cover, the first seal portion has a first annular portion located radially outside the outer peripheral surface of the bush and abutting the outer peripheral surface, a second annular portion located axially to one side of a first side surface on one axial side of the bush and abutting the first side surface, a connecting portion connecting the first annular portion and the second annular portion and being integrated with the first annular portion and the second annular portion, and a first lip portion adjacent to one axial side of the connecting portion and being integrated with the connecting portion.

[0012] In this way, the first seal portion abuts against the outer peripheral surface and the first side surface of the bushing, and therefore the first seal portion can hold the bushing in both the radial and axial directions.

[0013] In a preferred embodiment of the dust cover, the radial thickness of the first annular portion is greater than the axial thickness of the second annular portion. Here, the force acting on the bushing in the axial direction is smaller than the force acting on the bushing in the radial direction. Therefore, by increasing the rigidity of the first annular portion, the force that holds the bushing in the radial direction can be set to be greater than the force that holds the bushing in the axial direction.

[0014] In a preferred embodiment of the dust cover, the outer circumferential surface of the first annular portion, the outer circumferential surface of the connecting portion, and the outer circumferential surface of the first lip portion are flush with each other.

[0015] If the radial heights of the outer peripheral surface of the first annular portion, the outer peripheral surface of the connecting portion, and the outer peripheral surface of the first lip were all different, a step would be created between the first annular portion and the connecting portion, and a step would be created between the connecting portion and the first lip. When the vehicle is running, loads due to vehicle body vibrations are concentrated at the stepped portions, which could result in damage to the stepped portions. Therefore, by making the outer peripheral surfaces of the first annular portion, the connecting portion, and the first lip flush, it is possible to suppress the concentration of loads due to vehicle body vibrations.

[0016] In a preferred embodiment of the dust cover, the second seal portion has a third annular portion located radially outside the outer peripheral surface of the bush and abutting the outer peripheral surface, a fourth annular portion located axially on the other side of a second side surface on the other axial side of the bush and abutting the second side surface, a connecting portion connecting the third annular portion and the fourth annular portion and being integrated with the third annular portion and the fourth annular portion, and a second lip portion adjacent to the other axial side of the connecting portion and being integrated with the connecting portion.

[0017] In this way, the second seal portion abuts against the outer circumferential surface and the second side surface of the bushing, and therefore the second seal portion can hold the bushing in both the radial and axial directions.

[0018] In a preferred embodiment of the dust cover, the radial thickness of the third annular portion is greater than the axial thickness of the fourth annular portion. Therefore, the rigidity of the third annular portion is greater than the rigidity of the fourth annular portion. Here, the force acting on the bushing in the axial direction is smaller than the force acting on the bushing in the radial direction. Therefore, by increasing the rigidity of the third annular portion, the force that holds the bushing in the radial direction can be set to be greater than the force that holds the bushing in the axial direction.

[0019] In a preferred embodiment of the dust cover, the outer circumferential surface of the third annular portion, the outer circumferential surface of the connecting portion, and the outer circumferential surface of the second lip portion are flush with each other.

[0020] If the radial heights of the outer circumferential surface of the third annular portion, the outer circumferential surface of the connecting portion, and the outer circumferential surface of the second lip were all different, a step would be created between the third annular portion and the connecting portion, and a step would be created between the connecting portion and the second lip. When the vehicle is running, loads due to vibrations of the vehicle body are concentrated at the stepped portions, which could result in damage to the stepped portions. Therefore, by making the outer circumferential surfaces of the third annular portion, the connecting portion, and the second lip flush, it is possible to suppress the concentration of loads due to vibrations of the vehicle body.

[0021] In a preferred embodiment of the dust cover, when the seal member is not in contact with the bush, the axial length of the second annular portion of the first seal portion and the second annular portion of the second seal portion is smaller than the axial length of the bush.

[0022] Therefore, when the bushing is fitted into the inner periphery of the seal member, the first side surface of the bushing presses the side surface of the second annular portion toward one axial direction, and the second side surface of the bushing presses the side surface of the fourth annular portion toward the other axial direction. As a result, in a cross section including the central axis, the first seal portion rotates, for example, in a clockwise direction. The second seal portion rotates in a counterclockwise direction opposite to the first seal portion. As a result, the side surfaces of the first annular portion and the third annular portion approach each other in the axial direction. The radially inner end of the bellows is fitted into the recess. As described above, when the bushing is fitted into the inner periphery of the seal member, the radially inner end of the bellows can be more firmly sandwiched and held between the first annular portion and the third annular portion from both sides.

[0023] In a preferred embodiment of the dust cover, the tubular portion has a first protruding portion that protrudes radially outward and a second protruding portion that protrudes radially inward, the radially inner end of the bellows is provided with a recessed groove into which the first protruding portion fits, and the outer peripheral surface of the bush is provided with a recessed groove into which the second protruding portion fits.

[0024] Therefore, when an axial load is applied to the bellows, the first protruding portion restrains the axial movement of the bellows. Also, when an axial load is applied to the bushing, the second protruding portion restrains the axial movement of the bushing. Furthermore, when an axial load is applied to the seal member, the first protruding portion and the second protruding portion restrain the axial movement of the seal member. [Effects of the Invention]

[0025] According to the present disclosure, it is possible to provide a dust cover that can be manufactured with fewer work steps. [Brief explanation of the drawings]

[0026] [Figure 1] FIG. 1 is a schematic diagram of a steering device according to a first embodiment. [Figure 2] FIG. 2 is a perspective view of the steering device of the first embodiment. [Figure 3] FIG. 3 is a cross-sectional view of the dust cover attached to the vehicle. [Figure 4] FIG. 4 is a front view of the dust cover of the first embodiment. [Figure 5] FIG. 5 is a cross-sectional view taken along line VV in FIG. [Figure 6] FIG. 6 is a cross-sectional view of the bushing and seal member of FIG. [Figure 7] FIG. 7 is a cross-sectional view of the bushing of FIG. [Figure 8] FIG. 8 is a cross-sectional view of the seal member of FIG. [Figure 9] FIG. 9 is an enlarged schematic view of the first seal portion of FIG. [Figure 10] FIG. 10 is an enlarged schematic view of the second seal portion of FIG. [Figure 11] FIG. 11 is a cross-sectional view of a dust cover according to a first modified example. [Figure 12] FIG. 12 is a cross-sectional view of a dust cover according to the second embodiment. [Figure 13] FIG. 13 is a cross-sectional view of the bushing and seal member of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0027] The present invention will be described in detail below with reference to the drawings. Note that the present invention is not limited to the following modes for carrying out the invention (hereinafter referred to as embodiments). Furthermore, the components in the following embodiments include those that can be easily imagined by a person skilled in the art, those that are substantially the same, and those that are within the so-called equivalent range. Furthermore, the components disclosed in the following embodiments can be combined as appropriate. Note that in each drawing, the passenger compartment side is indicated as IN, and the engine room side is indicated as OUT.

[0028] [First embodiment] First, a first embodiment of the present invention will be described. Fig. 1 is a schematic diagram of a steering device of the first embodiment. Fig. 2 is a perspective view of the steering device of the first embodiment.

[0029] As shown in FIG. 1, the steering device 80 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, and is joined to a third steering shaft 87.

[0030] 1, the first steering shaft 82 includes 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. 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.

[0031] As shown in FIG. 1, second steering shaft 85 connects first universal joint 84 and second universal joint 86. One end of second steering shaft 85 is connected to first universal joint 84, and the other end is connected to second universal joint 86. One end of third steering shaft 87 is connected to second universal joint 86, and the other end of third steering shaft 87 is connected to steering gear 88. As shown in FIG. 2, second steering shaft 85 passes through dash panel 10. Dash panel 10 is a partition plate that separates the passenger compartment from the engine room.

[0032] As shown in FIG. 1, the steering gear 88 includes 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 by the rack 88b. The rack 88b is connected to a tie rod 89. The angle of the wheels changes as the rack 88b moves.

[0033] As shown in FIG. 1, the steering force assist mechanism 83 includes a reduction gear 92 and an electric motor 93. The reduction gear 92 is, for example, a worm reduction gear. Torque generated by the electric motor 93 is transmitted to a 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 via the worm and worm wheel. The reduction gear 92 then applies auxiliary steering torque to the output shaft 82b. In other words, the steering device 80 is a column assist type. A brief explanation of the column assist type is given below. Electric power steering is a system that assists steering of the steering wheel with a motor without using hydraulic pressure. Electric power steering types include, for example, a column assist type, a pinion assist type, and a rack assist type. Of these, the column assist type is, for example, a system in which a motor, a reduction gear, and a torque sensor are mounted on the column section of the steering shaft inside the vehicle cabin to drive the column shaft.

[0034] As shown in Fig. 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, the torque sensor 94, and the 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 traveling speed (vehicle speed) of the vehicle body on which the steering device 80 is mounted. The vehicle speed sensor 95 is provided on the vehicle body, and outputs the vehicle speed to the ECU 90 via CAN communication.

[0035] The ECU 90 controls the operation of the electric motor 93. The ECU 90 acquires signals from a torque sensor 94 and a vehicle speed sensor 95. When an ignition switch 98 is on, the ECU 90 is supplied with power from a power supply device 99 (for example, an on-board battery). The ECU 90 calculates an auxiliary steering command value based on the steering torque and the vehicle speed. The ECU 90 adjusts the value of power 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 in the electric motor 93. When the ECU 90 controls the electric motor 93, the force required to operate the steering wheel 81 is reduced.

[0036] Fig. 3 is a cross-sectional view of a dust cover attached to a vehicle. Fig. 4 is a front view of the dust cover of the first embodiment. Fig. 5 is a VV cross-sectional view of Fig. 4. Fig. 6 is a cross-sectional view of the bushing and seal member of Fig. 5. Fig. 7 is a cross-sectional view of the bushing of Fig. 5. Fig. 8 is a cross-sectional view of the seal member of Fig. 5. Fig. 9 is an enlarged schematic view of the first seal portion of Fig. 8. Fig. 10 is an enlarged schematic view of the second seal portion of Fig. 8.

[0037] In the following description, the direction along the central axis Z of the second steering shaft 85 will be referred to as the axial direction, the direction perpendicular to the axial direction will be referred to as the radial direction, and the direction along a circle centered on the central axis Z will be referred to as the circumferential direction. In addition, the engine room side (OUT) will also be referred to as one side in the axial direction, and the passenger compartment side (IN) will also be referred to as the other side in the axial direction.

[0038] As shown in FIG. 3, dash panel 10 includes a cylindrical member 101. The inner peripheral surface of cylindrical member 101 faces the outer peripheral surface 85a of second steering shaft 85. Second steering shaft 85 may move due to adjustment of the position of steering wheel 81 or vibrations during driving. For this reason, an annular gap is provided between the inner peripheral surface of cylindrical member 101 and the outer peripheral surface 85a of second steering shaft 85. To close this gap, steering device 80 includes dust cover 1.

[0039] The dust cover 1 is fitted onto the inner peripheral surface of a cylindrical member 101. The dust cover 1 is fixed to the cylindrical member 101 by a band 100 attached to the outer peripheral surface of the cylindrical member 101. The cylindrical member 101 is deformed when tightened by the band 100. For example, the cylindrical member 101 is formed from a metal. If the cylindrical member 101 is made of a metal, it is preferable that the cylindrical member 101 have a slit 102 along the axial direction as shown in FIG. 3. By having the slit 102 in the cylindrical member 101, the cylindrical member 101 can be easily deformed when tightened by the band 100.

[0040] 4 and 5, the dust cover 1 includes a bellows 2, a seal member 3, a bushing 5, and an attachment member 6. The bellows 2, the seal member 3, the bushing 5, and the attachment member 6 extend annularly in the circumferential direction around the central axis Z.

[0041] The mounting member 6 is a member that presses the bellows 2 against the cylindrical member 101 shown in FIG. 3. The mounting member 6 is made of, for example, an aluminum alloy. The mounting member 6 may also be made of a synthetic resin. As shown in FIG. 5, the mounting member 6 includes a main body portion 61 and a flange portion 62. The main body portion 61 is cylindrical and has an annular first 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 by the flange portion 62 coming into contact with the cylindrical member 101.

[0042] The bellows 2 is formed of, for example, rubber. As shown in FIG. 5 , the bellows 2 includes a radially inner end portion 20, a first flexible portion 21, a first fitting portion 22, a second flexible portion 25, and a second fitting portion 26. The radially inner end portion 20 is located at the radially inner end portion of the bellows 2. As shown in FIG. 5 , the first flexible portion 21 connects the radially inner end portion 20 and the first fitting portion 22. In a cross section including the central axis Z, the first flexible portion 21 has a generally U-shape that is convex toward the engine room (one axial side). The first fitting portion 22 fits into a first groove 611 of the mounting member 6. The second flexible portion 25 connects the radially inner end portion 20 and the second fitting portion 26. In a cross section including the central axis Z, the second flexible portion 25 has a generally U-shape that is convex toward the engine room (one axial side). The second fitting portion 26 is fitted 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 a radially inner end portion 20.

[0043] The bushing 5 is a bearing that rotatably supports the second steering shaft 85. As shown in FIG. 3 , the bushing 5 is attached to the outer peripheral surface 85a of the second steering shaft 85, which extends in the axial direction of the central axis Z while penetrating the cylindrical member 101 of the dash panel 10. The bushing 5 is made of a synthetic resin such as nylon. The bushing 5 is a cylindrical member that extends in the circumferential direction around the central axis Z of the second steering shaft 85. As shown in FIG. 7 , the bushing 5 has an outer peripheral surface 51, an inner peripheral surface 52, a first side surface 53, a second side surface 54, and a lubricant groove 55. The outer peripheral surface 51 is a smooth cylindrical surface. The inner peripheral surface 52 is provided with a lubricant groove 55. The lubricant groove 55 extends in the axial direction. The lubricant groove 55 extends, for example, over the entire axial length of the bushing 5. For example, a plurality of lubricant grooves 55 are arranged at equal intervals in the circumferential direction. The lubricant groove 55 is filled with grease as a lubricant, thereby reducing friction between the inner peripheral surface 52 of the bushing 5 and the outer peripheral surface 85a of the second steering shaft 85.

[0044] As shown in FIG. 5 , the seal member 3 is provided radially outside the bushing 5 and extends circumferentially around the central axis Z. As shown in FIG. 8 , the seal member 3 has a shape that is symmetrical with respect to the axial center CL. As shown in FIG. 8 , the seal member 3 includes a tubular portion 30, a first seal portion 31, and a second seal portion 32. In the seal member 3, the tubular portion 30, the first seal portion 31, and the second seal portion 32 are integrated. Here, "integrated" refers to a form in which the seal member 3 can be molded, for example, by filling a mold for injection molding with resin or rubber and removing it from the mold after hardening. Therefore, the tubular portion 30, the first seal portion 31, and the second seal portion 32 are all made of the same material. The seal member 3 is made of, for example, resin or rubber. The seal member 3 is harder than the bellows 2. As shown in FIG. 5 , a recess 110 is provided on the outer periphery of the seal member 3, into which the radially inner end portion 20 of the bellows 2 fits.

[0045] As shown in Fig. 5, the cylindrical portion 30 is sandwiched between the outer peripheral surface 51 of the bushing 5 and the radially inner end portion 20 of the bellows 2. As shown in Fig. 8, the cylindrical portion 30 axially connects the first seal portion 31 and the second seal portion 32. The cylindrical portion 30 has an outer peripheral surface 301 and an inner peripheral surface 302.

[0046] 5 and 6, the first seal portion 31 is provided on the engine compartment side (one axial side) of the tubular portion 30. A tip end 311 on the one axial side contacts the outer peripheral surface 85a of the second steering shaft (steering shaft) 85. As shown in FIG. 9, the first seal portion 31 has a first annular portion 312, a second annular portion 313, a connecting portion 314, and a first lip portion 315.

[0047] As shown in FIG. 9 , the first annular portion 312 is located radially outward of the outer peripheral surface 51 of the bushing 5. An inner peripheral surface 312a of the first annular portion 312 abuts against the outer peripheral surface 51. The end of the tubular portion 30 on the engine compartment side (one axial side) is the end 303 indicated by the two-dot chain line. Therefore, the boundary between the first annular portion 312 and the tubular portion 30 is the end 303. The boundary between the first annular portion 312 and the connecting portion 314 is the end 312c. A side surface 312b of the first annular portion 312 on the passenger compartment side extends radially outward from the end of the outer peripheral surface 301 of the tubular portion 30. Therefore, the recess 110 faces the side surface 312b and the outer peripheral surface 301. The bottom surface of the recess 110 is the outer peripheral surface 301. An outer peripheral surface 312d of the first annular portion 312 is located radially outward of the outer peripheral surface 301 of the tubular portion 30. Thus, the first annular portion 312 is a region surrounded by the inner circumferential surface 312a, the end 303, the side surface 312b, the end 312c, and the outer circumferential surface 312d. That is, the first annular portion 312 has a rectangular shape in a cross section including the central axis Z. The radial thickness D1 of the first annular portion 312 is greater than the radial thickness D2 of the tubular portion 30.

[0048] As shown in FIG. 9 , the second annular portion 313 is located closer to the engine compartment (one axial side) than the first side surface 53 of the bushing 5. The second annular portion 313 has a rectangular shape in a cross section including the central axis Z. Specifically, the second annular portion 313 is surrounded by a side surface 313a, a side surface 313b, an inner circumferential surface 313c, and an end 313d. The side surface 313a abuts against the first side surface 53. The thickness of the second annular portion 313 along the axial direction is an axial thickness D3. The radial thickness D1 is greater than the axial thickness D3. The radial thickness of the second annular portion 313 is approximately half the radial thickness of the bushing 5. Therefore, approximately half of the radial distance of the first side surface 53 abuts against the side surface 313a.

[0049] 9, the connecting portion 314 connects the first annular portion 312 and the second annular portion 313. The connecting portion 314 is integrated with the first annular portion 312 and the second annular portion 313. The connecting portion 314 has a rectangular shape in a cross section including the central axis Z. Specifically, the connecting portion 314 is surrounded by an end 312c, an end 314a, an end 313d, and an outer circumferential surface 314b.

[0050] As shown in FIG. 9 , first lip portion 315 is disposed adjacent to connecting portion 314 on the engine room side (one side in the axial direction). First lip portion 315 is integrated with connecting portion 314. First lip portion 315 is a region surrounded by end 314a, outer peripheral surface 315a, inner peripheral surface 315b, and side surface 315c. Inner peripheral surface 315b and side surface 315c taper toward tip 311. Outer peripheral surface 315a of first lip portion 315, outer peripheral surface 314b of connecting portion 314, and outer peripheral surface 312d of first annular portion 312 are flush with each other.

[0051] 5, the second seal portion 32 is provided on the passenger compartment side (the other axial side) of the tubular portion 30. A tip end 321 on the other axial side contacts an outer peripheral surface 85a of the second steering shaft (steering shaft) 85. As shown in FIG. 10, the second seal portion 32 has a third annular portion 322, a fourth annular portion 323, a connecting portion 324, and a second lip portion 325.

[0052] As shown in FIG. 10 , the third annular portion 322 is located radially outward of the outer peripheral surface 51 of the bushing 5. An inner peripheral surface 322a of the third annular portion 322 abuts against the outer peripheral surface 51. The end of the tubular portion 30 on the passenger compartment side (the other axial side) is the end 304 indicated by the two-dot chain line. Therefore, the boundary between the third annular portion 322 and the tubular portion 30 is the end 304. The boundary between the third annular portion 322 and the connecting portion 324 is the end 322c. A side surface 322b of the third annular portion 322 on the engine compartment side extends radially outward from the end of the outer peripheral surface 301 of the tubular portion 30. Therefore, the recess 110 faces the side surface 322b and the outer peripheral surface 301. The bottom surface of the recess 110 is the outer peripheral surface 301. An outer peripheral surface 322d of the third annular portion 322 is located radially outward of the outer peripheral surface 301 of the tubular portion 30. Thus, the third annular portion 322 is a region surrounded by the inner circumferential surface 322a, the end 304, the side surface 322b, the end 322c, and the outer circumferential surface 322d. That is, the third annular portion 322 has a rectangular shape in a cross section including the central axis Z. The radial thickness D4 of the third annular portion 322 is greater than the radial thickness D2 of the tubular portion 30.

[0053] As shown in FIG. 10 , the fourth annular portion 323 is located closer to the cabin (the other axial side) than the second side surface 54 of the bushing 5. The fourth annular portion 323 has a rectangular shape in a cross section including the central axis Z. Specifically, the fourth annular portion 323 is surrounded by a side surface 323a, a side surface 323b, an inner circumferential surface 323c, and an end 323d. The side surface 323a abuts against the second side surface 54. The thickness of the fourth annular portion 323 along the axial direction is an axial thickness D5. The radial thickness D4 is greater than the axial thickness D5. The radial thickness of the fourth annular portion 323 is approximately half the radial thickness of the bushing 5. Therefore, approximately half of the radial distance of the second side surface 54 abuts against the side surface 323a.

[0054] 10, the connecting portion 324 connects the third annular portion 322 and the fourth annular portion 323. The connecting portion 324 is integrated with the third annular portion 322 and the fourth annular portion 323. The connecting portion 324 has a rectangular shape in a cross section including the central axis Z. Specifically, the connecting portion 324 is surrounded by an end 322c, an end 324a, an end 323d, and an outer circumferential surface 324b.

[0055] As shown in FIG. 10 , second lip portion 325 is disposed adjacent to connecting portion 324 on the cabin side (the other side in the axial direction). Second lip portion 325 is integrated with connecting portion 324. Second lip portion 325 is a region surrounded by end 324a, outer peripheral surface 325a, inner peripheral surface 325b, and side surface 325c. Inner peripheral surface 325b and side surface 325c taper toward tip 321. Outer peripheral surface 325a of second lip portion 325, outer peripheral surface 324b of connecting portion 324, and outer peripheral surface 322d of third annular portion 322 are flush with each other.

[0056] 7 and 8, the movements of the first seal portion 31 and the second seal portion 32 when the bushing 5 is fitted into the inner periphery of the seal member 3 will be described. As shown in FIG. 7, the axial length of the bushing 5 is length D6. In other words, the axial separation distance between the first side surface 53 and the second side surface 54 is length D6. Also, as shown in FIG. 8, in the seal member 3, the axial length between the second annular portion 313 of the first seal portion 31 and the fourth annular portion 323 of the second seal portion 32 is length D7. In other words, the axial separation distance between the side surface 313a of the second annular portion 313 and the side surface 323a of the fourth annular portion 323 is length D7. Length D7 is shorter than length D6. Therefore, when the bushing 5 is fitted into the inner periphery of the seal member 3, the first side surface 53 of the bushing 5 presses the side surface 313a of the second annular portion 313 toward one axial side (the engine compartment side), and the second side surface 54 of the bushing 5 presses the side surface 323a of the fourth annular portion 323 toward the other axial side (the passenger compartment side). As a result, as indicated by arrow 120 in FIG. 8 , the first seal portion 31 rotates clockwise in a cross section including the central axis Z. Furthermore, as indicated by arrow 130 in FIG. 8 , the second seal portion 32 rotates counterclockwise. As a result, the side surface 312b of the first annular portion 312 and the side surface 322b of the third annular portion 322 approach each other in the axial direction. Because the radially inner end portion 20 of the bellows 2 is fitted into the recess 110, the side surfaces 312b and 322b exert a force to press the radially inner end portion 20 of the bellows 2 from both axial directions.

[0057] As described above, according to the first embodiment, the dust cover 1 comprises an annular bushing 5 attached to the outer peripheral surface 85a of the second steering shaft 85 (steering shaft) that penetrates the cylindrical member 101 of the dash panel 10 and extends in the axial direction of the central axis Z, one sealing member 3 that is provided radially outside the bushing 5 and extends circumferentially around the central axis Z, and a bellows 2 that seals the gap between the cylindrical member and the sealing member 3.

[0058] One seal member 3 has a tubular portion 30 that is clamped between the outer peripheral surface 51 of the bushing 5 and the radially inner end portion 20 of the bellows 2, a first seal portion 31 that is integrally formed with the tubular portion 30 on one axial side of the tubular portion 30 and has a tip 311 on one axial side that contacts the outer peripheral surface 85a of the second steering shaft 85 (steering shaft), and a second seal portion 32 that is integrally formed with the tubular portion 30 on the other axial side of the tubular portion 30 and has a tip 321 on the other axial side that contacts the outer peripheral surface 85a of the second steering shaft 85 (steering shaft).

[0059] As mentioned above, the dust cover of Patent Document 1 requires that the sealing member be bonded to the bushing, which increases the number of steps required to manufacture the dust cover. For example, when vulcanization bonding the sealing member, an adhesive is applied to the bushing, the adhesive is allowed to dry, and then the sealing member is vulcanization bonded via the adhesive.

[0060] In contrast, in the present embodiment, the first seal portion 31 and the second seal portion 32 are integrated via the tubular portion 30 to form a single seal member 3. Therefore, in the present embodiment, there is no need to join the first seal portion 31 and the second seal portion 32 to the bushing 5, as in Patent Document 1, and therefore manufacturing can be performed with fewer steps. Note that in Patent Document 1, when multiple seal members are simultaneously vulcanized and bonded, the mold structure becomes complex, resulting in increased mold costs. However, in the present embodiment, there is no vulcanization bonding step, and therefore mold costs are reduced. Furthermore, when the first seal portion 31 and the second seal portion 32 are integrated, the first seal portion 31 and the second seal portion 32 are more securely fixed to the bushing 5 than when the first seal portion 31 and the second seal portion 32 are separate. This makes them less likely to come off the bushing 5, enabling reliable sealing with the second steering shaft 85. Furthermore, since the first seal portion 31 and the second seal portion 32 are integrated, the axial positions of the first seal portion 31 and the second seal portion 32 are stable, and a stable seal with the second steering shaft 85 is obtained.

[0061] The seal member 3 is harder than the bellows 2. Here, the first seal portion 31 and the second seal portion 32 contact the outer peripheral surface 85a of the second steering shaft 85, and therefore, when the second steering shaft 85 rotates, the first seal portion 31 and the second seal portion 32 rub against the second steering shaft 85. However, when the seal member 3 is harder than the bellows 2, abnormal noise caused by rubbing against the second steering shaft 85 is reduced more than when the seal member 3 is softer than the bellows 2.

[0062] A recess 110 into which the radially inner end 20 of the bellows 2 fits is provided on the outer periphery of the sealing member 3, and the bottom surface of the recess 110 is the outer periphery surface 301 of the tubular portion 30. In this way, since the radially inner end 20 of the bellows 2 fits into the recess 110 on the outer periphery of the sealing member 3, the work of assembling the bellows 2 to the sealing member 3 is further simplified.

[0063] The first seal portion 31 has a first annular portion 312 located radially outside the outer peripheral surface 51 of the bushing 5 and abutting against the outer peripheral surface 51, a second annular portion 313 located on one axial side of a first side surface 53 on one axial side of the bushing 5 and abutting against the first side surface 53, a connecting portion 314 connecting the first annular portion 312 and the second annular portion 313 and being integrated with the first annular portion 312 and the second annular portion 313, and a first lip portion 315 adjacent to one axial side of the connecting portion 314 and being integrated with the connecting portion 314.

[0064] In this way, the first seal portion 31 abuts against the outer peripheral surface 51 and the first side surface 53 of the bushing 5. Therefore, the first seal portion 31 can hold the bushing 5 in both the radial and axial directions.

[0065] Because the radial thickness D1 of the first annular portion 312 is greater than the axial thickness D3 of the second annular portion 313, the rigidity of the first annular portion 312 is greater than the rigidity of the second annular portion 313. Here, the force acting in the axial direction on the bushing 5 is smaller than the force acting in the radial direction. Therefore, by increasing the rigidity of the first annular portion 312, the force that holds the bushing 5 in the radial direction can be set to be greater than the force that holds the bushing 5 in the axial direction.

[0066] The outer peripheral surface 312d of the first annular portion 312, the outer peripheral surface 314b of the connecting portion 314, and the outer peripheral surface 315a of the first lip portion 315 are all flush with each other. If the radial heights of the outer peripheral surface 312d, the outer peripheral surface 314b of the connecting portion 314, and the outer peripheral surface 315a of the first lip portion 315 were to be different, a step would be created between the first annular portion 312 and the connecting portion 314, and a step would be created between the connecting portion 314 and the first lip portion 315. When the vehicle is traveling, loads due to vibrations of the vehicle body are concentrated at the stepped portion, which may cause damage to the stepped portion. Therefore, by flushing the outer peripheral surface 312d of the first annular portion 312, the outer peripheral surface 314b of the connecting portion 314, and the outer peripheral surface 315a of the first lip portion 315, it is possible to suppress the concentration of loads due to vibrations of the vehicle body.

[0067] The second seal portion 32 has a third annular portion 322 located radially outside the outer peripheral surface 51 of the bushing 5 and abutting the outer peripheral surface 51, a fourth annular portion 323 located on the other axial side of the second side surface 54 on the other axial side of the bushing 5 and abutting the second side surface 54, a connecting portion 324 connecting the third annular portion 322 and the fourth annular portion 323 and being integrated with the third annular portion 322 and the fourth annular portion 323, and a second lip portion 325 adjacent to the other axial side of the connecting portion 324 and being integrated with the connecting portion 324.

[0068] In this way, the second seal portion 32 abuts against the outer peripheral surface 51 and the second side surface 54 of the bushing 5. Therefore, the second seal portion 32 can hold the bushing 5 in both the radial and axial directions.

[0069] Because the radial thickness D4 of the third annular portion 322 is greater than the axial thickness D5 of the fourth annular portion 323, the rigidity of the third annular portion 322 is greater than the rigidity of the fourth annular portion 323. Here, the force acting in the axial direction on the bushing 5 is smaller than the force acting in the radial direction. Therefore, by increasing the rigidity of the third annular portion 322, the force that holds the bushing 5 in the radial direction can be set to be greater than the force that holds the bushing 5 in the axial direction.

[0070] The outer peripheral surface 322d of the third annular portion 322, the outer peripheral surface 324b of the connecting portion 324, and the outer peripheral surface 325a of the second lip portion 325 are all flush with each other. If the radial heights of the outer peripheral surface 322d, the outer peripheral surface 324b of the connecting portion 324, and the outer peripheral surface 325a of the second lip portion 325 were to be different, a step would be created between the third annular portion 322 and the connecting portion 324, and a step would be created between the connecting portion 324 and the second lip portion 325. When the vehicle is traveling, loads due to vibrations of the vehicle body are concentrated at the stepped portion, which may cause damage to the stepped portion. Therefore, by flushing the outer peripheral surface 322d of the third annular portion 322, the outer peripheral surface 324b of the connecting portion 324, and the outer peripheral surface 325a of the second lip portion 325, it is possible to suppress the concentration of loads due to vibrations of the vehicle body.

[0071] When the seal member 3 is not in contact with the bush 5, the axial length D7 of the second annular portion 313 of the first seal portion 31 and the fourth annular portion 323 of the second seal portion 32 is smaller than the axial length D6 of the bush 5.

[0072] Therefore, when the bushing 5 is fitted into the inner periphery of the seal member 3, the first side surface 53 of the bushing 5 presses the side surface 313a of the second annular portion 313 toward one axial side (the engine compartment side), and the second side surface 54 of the bushing 5 presses the side surface 323a of the fourth annular portion 323 toward the other axial side (the passenger compartment side). As a result, as indicated by arrow 120 in FIG. 8 , the first seal portion 31 rotates clockwise in a cross section including the central axis Z. Furthermore, as indicated by arrow 130 in FIG. 8 , the second seal portion 32 rotates counterclockwise. As a result, the side surface 312b of the first annular portion 312 and the side surface 322b of the third annular portion 322 approach each other in the axial direction. The radially inner end portion 20 of the bellows 2 is fitted into the recess 110. As described above, when the bushing 5 is fitted into the inner circumference of the sealing member 3, the radially inner end portion 20 of the bellows 2 can be more firmly clamped and held from both the side surface 312b of the first annular portion 312 and the side surface 322b of the third annular portion 322.

[0073] [First Modification] Next, a first modified example will be described below. Fig. 11 is a cross-sectional view of a dust cover according to the first modified example.

[0074] The dust cover 1A of the first modified example is different from the dust cover 1 of the first embodiment in the structure of the mounting member 6A and the shape of the end of the bellows 2A, but other parts are the same. Only the differences will be described below.

[0075] 11, the mounting member 6A includes a main body 61 and a flange 62A. A through-hole 621A is provided so as to pass through the flange 62A.

[0076] As shown in FIG. 11 , the bellows 2A includes a radially inner end portion 20, a first flexible portion 21, a first fitting portion 22A, a second flexible portion 25, and a second fitting portion 26A. A recessed groove 221A is provided in the first fitting portion 22A. The first fitting portion 22A includes a flange 222A and a protrusion 223A at the end of the recessed groove 221A. The protrusion 223A extends from the flange 222A toward the passenger compartment and is inserted into a through-hole 621A in the flange portion 62A. The protrusion 223A has an expanded diameter portion 224A. The expanded diameter portion 224A functions to prevent the protrusion 223A from coming off. In this way, the first fitting portion 22A abuts against the main body portion 61 and the flange portion 62A of the mounting member 6A. The second fitting portion 26A protrudes radially inward and is fitted into the recessed groove 221A.

[0077] As described above, also in the first modified example, the first seal portion 31 and the second seal portion 32 are integrated via the tubular portion 30 to form a single seal member 3. Therefore, also in the first modified example, it is possible to provide a dust cover that can be manufactured with fewer man-hours than the dust cover disclosed in Patent Document 1.

[0078] [Second embodiment] Next, a second embodiment will be described. Fig. 12 is a cross-sectional view of a dust cover according to the second embodiment. Fig. 13 is a cross-sectional view of the bushing and the seal member of Fig. 12.

[0079] The dust cover 1B of the second embodiment differs from the dust cover 1 of the first embodiment mainly in the seal member 3B. Only the differences will be described below.

[0080] 13, the seal member 3B includes a tubular portion 30B, a first seal portion 31B, and a second seal portion 32B. In the seal member 3B, the tubular portion 30B, the first seal portion 31B, and the second seal portion 32B are integrated together.

[0081] As shown in Fig. 13, the cylindrical portion 30B has a first protrusion 304B and a second protrusion 305B. The first protrusion 304B and the second protrusion 305B are provided at the axial center of the cylindrical portion 30B. The first protrusion 304B protrudes radially outward from the outer peripheral surface 301. The second protrusion 305B protrudes radially inward from the inner peripheral surface 302. The first protrusion 304B and the second protrusion 305B are rectangular in a cross section including the central axis Z.

[0082] 12, a groove 201B is provided in the radially inner end 20B of the bellows 2B, and the first protrusion 304B fits into the groove 201B. Also, a groove 511B is provided in the outer peripheral surface 51 of the bushing 5, and the second protrusion 305B fits into the groove 511B.

[0083] As described above, the cylindrical portion 30B has the first protruding portion 304B protruding radially outward and the second protruding portion 305B protruding radially inward. The radially inner end portion 20B of the bellows 2B is provided with a recessed groove 201B into which the first protruding portion 304B fits, and the outer peripheral surface 51 of the bushing 5B is provided with a recessed groove 511B into which the second protruding portion 305B fits.

[0084] Therefore, when an axial load is applied to bellows 2B, first protrusion 304B suppresses axial movement of bellows 2B. Furthermore, when an axial load is applied to bushing 5B, second protrusion 305B suppresses axial movement of bushing 5B. Furthermore, when an axial load is applied to seal member 3B, first protrusion 304B and second protrusion 305B suppress axial movement of seal member 3B. [Explanation of symbols]

[0085] 1, 1A, 1B dust cover 2, 2A, 2B Bellows 3, 3B sealing material 5, 5B Bush 6, 6A Mounting parts 10 Dash Panel 20, 20B Radial inner end 21 First flexible part 22, 22A 1st mating part 25 Second flexible part 26, 26A 2nd mating part 30, 30B cylinder part 31, 31B First seal part 32, 32B Second seal part 51 Outer surface 52 Inner surface 53 First aspect 54 Second aspect 55 Lubricant groove 61 Main body 62, 62A flange 80 Steering device 81 Steering wheel 82 First steering shaft 82a Input shaft 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 Slit 110 recess 120, 130 arrows 201B Groove 221A Groove 222A flange 223A protrusion 224A expansion section 301 outer surface 302 inner surface 303 End 304 End 304B 1st protrusion 305B Second protrusion 311 apex 312 1st annular part 312a inner surface 312b side 312c side 312d outer surface 313 Second annular part 313a Side 313b side 313c inner surface 313d end 314 Connection 314a terminal 314b outer surface 315 Part 1 Ripple 315a outer surface 315b inner surface 315c side 321 apex 322 Third annular part 322a inner circumference 322b Side 322c terminal 322d outer surface 323 4th annular part 323a Side 323b Side 323c inner surface 323d end 324 Connection 324b outer surface 325 Part 2 Ripple 325a outer surface 325b inner surface 325c side 511B groove 611 No. 1 Ditch 621A Through hole Z center axis

Claims

1. an annular bushing attached to an outer peripheral surface of a steering shaft that extends in the axial direction of the central axis while passing through a cylindrical member of the dash panel; a seal member provided radially outside the bushing in contact with an outer peripheral surface of the bushing and extending in a circumferential direction around the central axis; a bellows that closes a gap between the cylindrical member and the sealing member and is separate from the one sealing member; Equipped with the bellows has a radially inner end portion that abuts against the one seal member; The one sealing member is a cylindrical portion that is disposed between an outer peripheral surface of the bushing and the radially inner end of the bellows, extends in the axial direction, has a front surface that abuts against the radially inner end of the bellows, a back surface that abuts against the outer peripheral surface of the bushing, and is sandwiched between the outer peripheral surface of the bushing and the radially inner end of the bellows; a first seal portion provided integrally with the cylindrical portion on one side in the axial direction, the first seal portion having a tip on the one side in the axial direction in contact with an outer peripheral surface of the steering shaft; a second seal portion provided integrally with the cylindrical portion on the other side in the axial direction, the second seal portion having a tip on the other side in the axial direction in contact with an outer peripheral surface of the steering shaft; having Dust cover.

2. The sealing member is harder than the bellows. The dust cover according to claim 1 .

3. a recess into which the radially inner end of the bellows fits is provided on an outer periphery of the seal member, The bottom surface of the recess is the outer circumferential surface of the cylindrical portion.

3. The dust cover according to claim 1 or 2.

4. The first seal portion is a first annular portion located radially outward of an outer circumferential surface of the bushing and in contact with the outer circumferential surface; a second annular portion located on one axial side of a first side surface on one axial side of the bush and abutting against the first side surface; a connecting portion that connects the first annular portion and the second annular portion and is integrated with the first annular portion and the second annular portion; a first lip portion adjacent to one axial side of the connecting portion and integrated with the connecting portion; 3. The dust cover according to claim 1 or 2.

5. A radial thickness of the first annular portion is greater than an axial thickness of the second annular portion. The dust cover according to claim 4.

6. An outer circumferential surface of the first annular portion, an outer circumferential surface of the connecting portion, and an outer circumferential surface of the first lip portion are flush with each other.

6. The dust cover according to claim 4 or 5.

7. The second seal portion is a third annular portion located radially outward of an outer circumferential surface of the bushing and in contact with the outer circumferential surface; a fourth annular portion located on the other axial side of a second side surface of the bushing and in contact with the second side surface; a connecting portion that connects the third annular portion and the fourth annular portion and is integrated with the third annular portion and the fourth annular portion; a second lip portion adjacent to the other axial side of the connecting portion and integrated with the connecting portion; The dust cover according to any one of claims 1 to 6.

8. The radial thickness of the third annular portion is greater than the axial thickness of the fourth annular portion. The dust cover according to claim 7.

9. An outer circumferential surface of the third annular portion, an outer circumferential surface of the connecting portion, and an outer circumferential surface of the second lip portion are flush with each other.

9. The dust cover according to claim 7 or 8.

10. When the seal member is not in contact with the bush, The axial lengths of the second annular portion of the first seal portion and the fourth annular portion of the second seal portion are the axial length of the bushing is smaller than that of the bushing; The dust cover according to claim 7.

11. The cylindrical portion is a first protruding portion protruding radially outward; a second protruding portion protruding radially inward, a recessed groove into which the first protrusion fits is provided at the radially inner end of the bellows, a recessed groove into which the second protrusion fits is provided on the outer circumferential surface of the bushing; 3. The dust cover according to claim 1 or 2.

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