Cover, sealing device, and steering device

Abstract

Provided are a cover, a sealing device, and a steering device that are capable of sufficiently exhibiting a sealing function even in a flooded environment.　A cover 200 is provided to a steering device comprising a pinion shaft 40 and a housing 60 that has an insertion hole 61 into which the pinion shaft 40 is inserted, said cover 200 characterized by comprising a rubber-like elastic body 220 integrally having a large-diameter seal part 221 which is fixed in a state in close contact with the outer peripheral surface of the housing 60, and a small-diameter seal part 223 which is in slidable close contact with the outer peripheral surface of the pinion shaft 40 and of which the inner diameter is smaller than that of the large-diameter seal part 221.

Description

Cover, sealing device, and steering device

[0001] The present invention relates to a cover, a sealing device, and a steering device.

[0002] In a steering device, a sealing device is provided to seal a gap between a pinion shaft and a housing having an insertion hole through which the pinion shaft is inserted. When only a so-called oil seal is employed as the sealing device, the oil seal is exposed to dust and water, which degrades the sealing performance and significantly reduces durability. Therefore, a technology is known in which a cover is provided separately from the oil seal. Such a conventional sealing device will be described with reference to FIG. 4. FIG. 4 is a schematic cross-sectional view of a steering device including a conventional sealing device.

[0003] As shown in FIG. 4, in the steering device, a main seal 100 (oil seal) is provided to seal an annular gap between a pinion shaft 40 and a housing 60 having an insertion hole through which the pinion shaft 40 is inserted. In this conventional example, a cover 500 is provided to improve the durability of the main seal 100. This suppresses adhesion of dust and water to the main seal 100, thereby suppressing degradation of the sealing performance of the main seal 100 and improving durability.

[0004] The cover 500 according to the conventional example configured as described above has an umbrella-shaped structure, and exhibits a function of suppressing intrusion of dust and water into the main seal 100 by causing dust and water to flow down to the outside of the housing 60. Therefore, when the vehicle travels through a deep puddle or the like where the water surface is higher than the upper end of the housing 60, water intrudes as indicated by arrow X in the figure, so the cover 500 cannot exhibit its function.

[0005] Japanese Patent Application Laid-Open No. 2017-136955, Japanese Patent Application Laid-Open No. 2022-91275

[0006] An object of the present invention is to provide a cover, a sealing device, and a steering device that can sufficiently exhibit a sealing function even in a flooded environment.

[0007] To solve the above problems, the present invention employs the following means.

[0008] In other words, the cover of the present invention is a cover provided on a steering device comprising a pinion shaft and a housing having an insertion hole through which the pinion shaft is inserted, and is characterized by comprising a rubber-like elastic body integrally having a large-diameter sealing portion fixed in close contact with the outer circumferential surface of the housing and a small-diameter sealing portion that slidably adheres to the outer circumferential surface of the pinion shaft and whose inner diameter is smaller than that of the large-diameter sealing portion.

[0009] Here, the cover is preferably positioned on the side opposite to the area to be sealed, via a main seal that seals the annular gap between the inner surface of the insertion hole and the outer surface of the pinion shaft.

[0010] Furthermore, the sealing device of the present invention is a sealing device provided in a steering device comprising a pinion shaft and a housing having an insertion hole through which the pinion shaft is inserted, and comprises a main seal that seals the annular gap between the inner circumferential surface of the insertion hole and the outer circumferential surface of the pinion shaft, and a cover disposed on the opposite side from the area to be sealed via the main seal, wherein the cover comprises a rubber-like elastic body integrally having a large-diameter sealing portion fixed in close contact with the outer circumferential surface of the housing, and a small-diameter sealing portion that slidably adheres to the outer circumferential surface of the pinion shaft and whose inner diameter is smaller than that of the large-diameter sealing portion.

[0011] Furthermore, the steering device of the present invention comprises: a pinion shaft; a housing having an insertion hole through which the pinion shaft is inserted; a main seal that seals the annular gap between the inner circumferential surface of the insertion hole and the outer circumferential surface of the pinion shaft; and a cover disposed on the opposite side of the area to be sealed via the main seal, wherein the cover comprises a rubber-like elastic body integrally having a large-diameter sealing portion fixed in close contact with the outer circumferential surface of the housing, and a small-diameter sealing portion that slidably adheres to the outer circumferential surface of the pinion shaft and whose inner diameter is smaller than that of the large-diameter sealing portion.

[0012] According to these inventions, the cover blocks the entry route of dust and water into the annular gap between the inner surface of the through hole in the housing and the outer surface of the pinion shaft. This prevents water from entering the annular gap even in flooded environments. Consequently, the deterioration of the sealing function of the main seal can be suppressed, and the durability of the main seal can also be increased.

[0013] The rubber-like elastic body may have a stopper portion that extends radially inward from the large-diameter sealing portion and abuts against the front surface of the housing.

[0014] This allows for improved positioning accuracy of the cover when attaching it to the housing, as the stopper portion only needs to be fitted in until it abuts against the front surface of the housing.

[0015] The rubber-like elastic body has a body portion that extends from the stopper portion toward the small-diameter seal portion, and the body portion is preferably configured to decrease in diameter toward the small-diameter seal portion and to expand from the inside toward the outside.

[0016] This prevents the cover from flipping over when attaching it to the housing, thus stabilizing the cover's position.

[0017] It is preferable that a reinforcing ring be embedded inside the large-diameter sealing portion.

[0018] This allows the cover to be securely fixed to the housing.

[0019] Furthermore, the above configurations can be combined and adopted as much as possible.

[0020] As explained above, according to the present invention, the sealing function can be fully performed even in flooded environments.

[0021] Figure 1 is a main configuration diagram of a steering device according to an embodiment of the present invention. Figure 2 is a schematic cross-sectional view of a steering device equipped with a sealing device according to an embodiment of the present invention. Figure 3 is a part of a schematic cross-sectional view of a cover according to an embodiment of the present invention. Figure 4 is a schematic cross-sectional view of a steering device equipped with a sealing device according to a conventional example.

[0022] The embodiments for carrying out this invention will be described in detail below with reference to the drawings, based on examples. However, unless otherwise specifically stated, the dimensions, materials, shapes, and relative arrangements of the components described in these embodiments are not intended to limit the scope of this invention to those components alone.

[0023] (Examples) Referring to Figures 1 to 3, a cover, a sealing device, and a steering device according to an embodiment of the present invention will be described. Figure 1 is a main configuration diagram of a steering device according to an embodiment of the present invention, showing only the main components in a simplified manner, and the components near the sealing device are shown in a schematic cross-sectional view. Note that the scale differs from that of a typical product in order to clarify the main components. Figure 2 is a schematic cross-sectional view of a steering device equipped with a sealing device according to an embodiment of the present invention, showing only the components near the sealing device in an enlarged view. Figure 3 is a part of a schematic cross-sectional view of a cover according to an embodiment of the present invention. The sealing device according to this embodiment is a rotating body, and the schematic cross-sectional views in Figures 1 to 3 are cross-sectional views obtained by cutting the sealing device with a plane including the central axis of the rotating body. Note that the sealing device does not need to be a complete rotating body, and a part of the circumferential direction may have a different shape from other parts.

[0024] <Steering Device> Referring to Figure 1, the steering device 1 according to this embodiment will be described. The steering device 1 comprises a steering wheel 10 and a pinion shaft 40 connected to a shaft 20 that rotates in conjunction with the rotation of the steering wheel 10 via a universal joint 30. A pinion 41 is provided at the tip of the pinion shaft 40, which is configured to mesh with a rack 51 provided on a rack shaft 50. With this rack and pinion mechanism, the rotation of the pinion shaft 40 in conjunction with the rotation of the steering wheel 10 causes the rack shaft 50 to reciprocate from left to right in the figure. Wheels are also provided on both sides of the rack shaft 50, and the direction of the wheels is configured to change in accordance with the reciprocating movement of the rack shaft 50.

[0025] Furthermore, the steering device 1 is provided with a housing 60 for housing various components, such as the components that make up the rack and pinion mechanism. In Figure 1, only a portion of the housing 60 is shown. The housing 60 is provided with an insertion hole 61 through which the pinion shaft 40 is inserted. The pinion shaft 40 is configured to rotate relative to the housing 60 by a ball bearing 70 attached to the inner circumferential surface of the insertion hole 61. The pinion shaft 40 is configured to rotate within a certain range relative to the housing 60 and to reciprocate slightly.

[0026] Furthermore, in the steering device 1, a sealing device 80 is provided to prevent dust and water from entering the annular gap between the inner surface of the insertion hole 61 and the outer surface of the pinion shaft 40.

[0027] <Sealing Device> The sealing device 80 will be described with reference to Figure 2. The sealing device 80 includes a main seal 100 that seals the annular gap between the inner circumferential surface of the insertion hole 61 and the outer circumferential surface of the pinion shaft 40, and a cover 200 that is positioned on the opposite side of the area to be sealed via the main seal 100.

[0028] For the main seal 100, various known technologies capable of sealing the annular gap between two relatively rotating members can be employed. In this embodiment, an example of the main seal 100 is shown in which a so-called oil seal is used. This main seal 100 comprises a reinforcing ring 110 made of metal or hard resin, a seal body 120 made of a rubber-like elastic material integrally provided on the reinforcing ring 110, and a garter spring 130. The seal body 120 comprises a main lip 121 and a dust lip 122 that slidably adhere to the outer circumferential surface of the pinion shaft 40, and an outer circumferential seal portion 123 that is fixed by press-fitting to the inner circumferential surface of the insertion hole 61 of the housing 60. By attaching the garter spring 130 to the outer circumference of the main lip 121, the inner lip tip of the main lip 121 maintains a stable state of adhesion to the outer circumferential surface of the pinion shaft 40.

[0029] As described above, the main seal 100 is located inside the housing 60 and plays the role of sealing the annular gap between the inner circumferential surface of the insertion hole 61 and the outer circumferential surface of the pinion shaft 40. In contrast, the cover 200 is located outside the housing 60 and plays the role of blocking the entry routes of dust and water into the annular gap between the inner circumferential surface of the insertion hole 61 and the outer circumferential surface of the pinion shaft 40. The cover 200 will be described in more detail below.

[0030] <Cover> The cover 200 will be described with reference to Figures 2 and 3. Figure 2 shows the cover 200 attached to the housing 60 and the pinion shaft 40, and Figure 3 shows the cover 200 alone. Figure 3(a) shows the cover 200 according to this embodiment, and (b) and (c) show modified examples in which some of the components of the cover 200 have been altered.

[0031] The cover 200 is composed of a reinforcing ring 210 made of metal or hard resin, and a rubber-like elastic body 220 made of rubber (for example, chloroprene) integrally provided on the reinforcing ring 210. This cover 200 can be obtained by molding the rubber-like elastic body 220 by insert molding, using the reinforcing ring 210 as an insert component.

[0032] The reinforcing ring 210 is an annular member with a substantially L-shaped cross-section, comprising a cylindrical portion 211 and an inward-facing flange portion 212 provided at the tip of the cylindrical portion 211. The rubber-like elastic body 220 comprises a large-diameter sealing portion 221 fixed in close contact with the outer circumferential surface of the housing 60, and a small-diameter sealing portion 223 that slidably adheres to the outer circumferential surface of the pinion shaft 40 and has an inner diameter smaller than that of the large-diameter sealing portion 221. In this embodiment, the sliding sealing portion on the inner circumferential surface of the small-diameter sealing portion 223 is composed of a plurality of annular protrusions 223a. In this embodiment, the sliding sealing portion of the small-diameter sealing portion 223 is configured to slide against a small-diameter portion 42 provided on a part of the pinion shaft 40. As a result, even when the pinion shaft 40 reciprocates relative to the housing 60, the movement of the small-diameter sealing portion 223 is restricted by the stepped surfaces above and below the small-diameter portion 42. Therefore, the posture of the cover 200 is stably maintained, and the sealing function can be stabilized.

[0033] Furthermore, the rubber-like elastic body 220 has a stopper portion 222 that extends radially inward from the large-diameter sealing portion 221 and abuts against the front surface of the housing 60. In addition, the rubber-like elastic body 220 has a body portion 224 that extends from the stopper portion 222 toward the small-diameter sealing portion 223. This body portion 224 is configured to decrease in diameter from the stopper portion 222 toward the small-diameter sealing portion 223 and to bulge from the inside toward the outside.

[0034] The large-diameter sealing portion 221, stopper portion 222, small-diameter sealing portion 223, and body portion 224 are integrally provided. Furthermore, the reinforcing ring 210 is embedded inside the large-diameter sealing portion 221.

[0035] <Advantages of the cover, sealing device, and steering device according to this embodiment> According to this embodiment, the cover 200 blocks the entry route of dust and water into the annular gap between the inner circumferential surface of the insertion hole 61 in the housing 60 and the outer circumferential surface of the pinion shaft 40. As a result, even in environments where the vicinity of the sealing device 80 is flooded, it is possible to suppress water from entering the annular gap. Accordingly, the deterioration of the sealing function of the main seal 100 is suppressed, allowing it to fully perform its sealing function, and the durability of the main seal 100 can also be increased.

[0036] Furthermore, since the rubber-like elastic body 220 in this embodiment has a stopper portion 222, when attaching the cover 200 to the housing 60, it is sufficient to fit it in until the stopper portion 222 abuts against the front surface of the housing 60. This makes it easy to improve the positioning accuracy of the cover 200.

[0037] Furthermore, the body portion 224 of the rubber-like elastic body 220 according to this embodiment is configured to decrease in diameter from the stopper portion 222 towards the small-diameter sealing portion 223, and to bulge from the inside out. Therefore, when attaching the cover 200 to the housing 60, it is possible to prevent the cover 200 from turning over and to stabilize the posture of the cover 200.

[0038] Furthermore, in this embodiment, since a reinforcing ring 210 is embedded inside the large-diameter sealing portion 221, the cover 200 can be firmly fixed to the housing 60.

[0039] Furthermore, if the reinforcing ring 210 is not provided, it is not necessary to provide it if the force required to fix the large-diameter seal portion 221 to the housing 60 can be obtained under certain conditions. Figure 3(b) shows a cover 200A configured in this way. This cover 200A has the same configuration as the cover 200 described above, except that it does not have a reinforcing ring 210, so the same reference numerals are used for the same components and their descriptions are omitted.

[0040] Furthermore, in the cover 200 described above, the sliding seal portion on the inner circumferential surface of the small-diameter seal portion 223 is shown to be composed of a plurality of annular protrusions 223a. However, the configuration of the sliding seal portion can be appropriately set according to the required usage conditions, etc. An example is shown in Figure 3(c). In the cover 200B shown in this figure, the sliding seal portion on the inner circumferential surface of the small-diameter seal portion 223B is composed of a seal lip 223Ba provided at the tip of the small-diameter seal portion 223B and an annular protrusion 223Bb provided on the larger-diameter seal portion 221 side of the seal lip 223Ba. The seal lip 223Ba mainly performs a sealing function, and the annular protrusion 223Bb mainly performs a function to stabilize the posture of the small-diameter seal portion 223B. In the cover 200B configured as described above, the configuration is the same as the cover 200 described above, except for the configuration related to the small-diameter seal portion 223B, so the same reference numerals are used for the same components and their descriptions are omitted. Furthermore, in this cover 200B as well, a configuration without the reinforcing ring 210 can be adopted depending on the usage conditions.

[0041] Cover 200 offers easier sealing performance compared to cover 200B. On the other hand, cover 200B offers easier reduction of sliding torque compared to cover 200. Thus, the configuration of the sliding seal section can be appropriately set according to the required operating conditions.

[0042] 1: Steering device 10: Steering wheel 20: Shaft 30: Universal joint 40: Pinion shaft 41: Pinion 42: Small diameter section 50: Rack shaft 51: Rack 60: Housing 61: Through hole 70: Ball bearing 80: Sealing device 100: Main seal 110: Reinforcing ring 120: Seal body 121: Main lip 122: Dust lip 123: Outer circumference seal section 130: Garter spring 200, 200A, 200B: Cover 210: Reinforcing ring 211: Cylindrical section 212: Inward flange section 220: Rubber-like elastic body 221: Large diameter seal section 222: Stopper section 223, 223B: Small diameter seal section 223Ba: Seal lip 223Bb: Annular projection 223a: Annular projection 224: Body section

Claims

1. A cover provided on a steering device comprising a pinion shaft and a housing having a through hole through which the pinion shaft is inserted, characterized in that the cover comprises a rubber-like elastic body integrally having a large-diameter sealing portion fixed in close contact with the outer circumferential surface of the housing and a small-diameter sealing portion that slidably adheres to the outer circumferential surface of the pinion shaft and whose inner diameter is smaller than that of the large-diameter sealing portion.

2. The cover according to claim 1, characterized in that it is positioned on the opposite side of the area to be sealed via a main seal that seals the annular gap between the inner circumferential surface of the insertion hole and the outer circumferential surface of the pinion shaft.

3. The cover according to claim 1 or 2, characterized in that the rubber-like elastic body extends radially inward from the large-diameter sealing portion and has a stopper portion that abuts against the front end surface of the housing.

4. The cover according to claim 3, wherein the rubber-like elastic body has a body portion extending from the stopper portion toward the small-diameter seal portion, and the body portion is configured to decrease in diameter toward the small-diameter seal portion toward the stopper portion and to expand toward the outside from the inside.

5. The cover according to claim 1 or 2, characterized in that a reinforcing ring is embedded inside the large-diameter sealing portion.

6. A sealing device provided in a steering device comprising a pinion shaft and a housing having a through hole through which the pinion shaft is inserted, the sealing device comprising: a main seal that seals the annular gap between the inner circumferential surface of the through hole and the outer circumferential surface of the pinion shaft; and a cover disposed on the opposite side from the area to be sealed via the main seal, wherein the cover comprises a rubber-like elastic body integrally having a large-diameter sealing portion fixed in close contact with the outer circumferential surface of the housing, and a small-diameter sealing portion that slidably adheres to the outer circumferential surface of the pinion shaft and whose inner diameter is smaller than that of the large-diameter sealing portion.

7. The sealing device according to claim 6, characterized in that the rubber-like elastic body extends radially inward from the large-diameter sealing portion and has a stopper portion that abuts against the front end surface of the housing.

8. The sealing device according to claim 7, characterized in that the rubber-like elastic body has a body portion extending from the stopper portion toward the small-diameter sealing portion, and the body portion is configured to decrease in diameter toward the small-diameter sealing portion toward the stopper portion and to expand toward the outside from the inside.

9. The sealing device according to claim 6, 7, or 8, characterized in that a reinforcing ring is embedded inside the large-diameter sealing portion.

10. A steering device comprising: a pinion shaft; a housing having a through hole through which the pinion shaft is inserted; a main seal that seals the annular gap between the inner circumferential surface of the through hole and the outer circumferential surface of the pinion shaft; and a cover disposed on the opposite side of the area to be sealed via the main seal, wherein the cover comprises a rubber-like elastic body integrally having a large-diameter sealing portion fixed in close contact with the outer circumferential surface of the housing, and a small-diameter sealing portion that slidably adheres to the outer circumferential surface of the pinion shaft and whose inner diameter is smaller than that of the large-diameter sealing portion.

11. The steering device according to claim 10, characterized in that the rubber-like elastic body extends radially inward from the large-diameter sealing portion and has a stopper portion that abuts against the front end surface of the housing.

12. The steering device according to claim 11, wherein the rubber-like elastic body has a body portion extending from the stopper portion toward the small-diameter seal portion, and the body portion is configured to decrease in diameter toward the small-diameter seal portion toward the stopper portion and to expand from the inside toward the outside.

13. The steering device according to claim 10, 11, or 12, characterized in that a reinforcing ring is embedded inside the large-diameter seal portion.

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