Seal member

Abstract

To eliminate influence of a seal member on a leak test performed by filling with gas.SOLUTION: A seal member 90 for sealing between an outer peripheral surface of a steering shaft 11 and an inner peripheral surface of an accommodation part 81 in which the steering shaft 11 is accommodated, comprises an annular body part 91 provided between the outer peripheral surface of the steering shaft 11 and the inner peripheral surface of the accommodation part 81, and a filter 99 that is permeable to gas but not to liquid. The body part 91 is provided with a ventilation part 97 that penetrates the body part 91 in an axial direction. The filter 99 is provided in the ventilation part 97.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a seal member. [Background technology]

[0002] Patent Document 1 discloses an electric power steering device including a pinion shaft, a rack shaft that meshes with a pinion on the outer periphery of the pinion shaft, a torque detection device that detects input torque to the pinion shaft, an electric motor that applies an assist force to steering based on a detection signal from the torque detection device, and a housing that accommodates the pinion shaft and the rack shaft.

[0003] The housing has a pinion-side housing that accommodates the pinion shaft, a connection housing that accommodates the meshing portion of the pinion gear and rack gear, and a rack-side housing that accommodates the rack shaft. An oil seal is provided between the pinion shaft and the connection housing. Even if the boot covering the rack shaft is damaged, the oil seal prevents foreign matter from entering the pinion-side housing, protecting the torque detection device and other devices in the pinion-side housing. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 10-258749 Summary of the Invention [Problem to be solved by the invention]

[0005] Generally, an oil seal seals both liquid and gas. In the electric power steering device described in Patent Document 1, an oil seal is provided in the connecting housing between the pinion side housing and the rack side housing. Therefore, when filling the housing with gas during manufacturing to perform a leak test, it is not possible to fill the entire housing with gas at once, and it is necessary to fill the pinion side housing and the rack side housing with gas separately. In other words, the provision of the oil seal makes the leak test more time-consuming.

[0006] The present invention has been made in consideration of the above problems, and has an object to eliminate the effect of the seal member on a leak test that is carried out by filling a gas. [Means for solving the problem]

[0007] The present invention provides a sealing member that seals between the outer peripheral surface of a shaft and the inner peripheral surface of a storage section in which the shaft is housed, and is characterized in that it comprises an annular main body portion provided between the outer peripheral surface of the shaft and the inner peripheral surface of the storage section, and a filter that is permeable to gas but not permeable to liquid, wherein a ventilation portion that penetrates the main body portion in the axial direction is formed, and the filter is provided in the ventilation portion.

[0008] In this invention, a filter that is permeable to gas but not to liquid is provided in the ventilation portion of the main body of the seal member. Therefore, the seal member seals the gap between the outer circumferential surface of the shaft and the inner circumferential surface of the housing portion so that gas can pass through but liquid cannot pass through. This eliminates the effect of the seal member on a leak test that is performed by filling the space with gas.

[0009] The present invention is characterized in that the main body portion has an annular core portion formed of metal and an annular seal portion in which the core portion is provided, and the ventilation portion is formed in the core portion and the seal portion.

[0010] The present invention is characterized in that a plurality of ventilation portions are formed at intervals in the circumferential direction of the main body portion.

[0011] In these inventions, even if one of the ventilation parts is blocked by a foreign object or the like, gas can still pass through the other ventilation parts.

[0012] The present invention is characterized in that the filter is provided to cover the opening of the ventilation portion formed in the core metal portion, and the core metal portion is formed with a positioning portion that engages with the filter to position the filter.

[0013] In this invention, the filter can be easily positioned by the positioning portion.

[0014] The present invention is characterized in that the filter is provided to cover the opening of the ventilation portion formed in the core metal portion, and the edge of the filter is sandwiched between the seal portion and the core metal portion.

[0015] In this invention, the edge of the filter is sandwiched between the seal portion and the core metal portion, so that the filter can be easily positioned in the axial direction. Effect of the Invention

[0016] According to the present invention, it is possible to eliminate the influence of the seal member on a leak test that is carried out by filling the gas. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a configuration diagram of an electric power steering device. [Diagram 2] FIG. [Diagram 3] FIG. 2 is a perspective view of a seal member according to the embodiment. [Figure 4] FIG. [Diagram 5] FIG. 4 is a cross-sectional view taken along line VV in FIG. [Figure 6] FIG. 6 is an enlarged cross-sectional view of A shown in FIG. 5. [Figure 7] FIG. 11 is a perspective view of a core part according to a modified example of the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] A seal member 90 according to an embodiment of the present invention will be described with reference to the drawings.

[0019] The seal member 90 of this embodiment is provided in an electric power steering device 100. As shown in Fig. 1, the electric power steering device 100 includes a steering shaft 11 that rotates in response to steering of a steering wheel 1 by a driver, a first pinion gear 16 that is provided on the steering shaft 11 and rotates together with the steering shaft 11, and a rack shaft 12 that has a rack gear 12a that meshes with the first pinion gear 16 and steers the wheels 2.

[0020] The steering shaft 11 has an input shaft 13 that rotates in conjunction with the steering operation of the driver operating the steering wheel 1, an output shaft 15 that displaces the rack shaft 12, and a torsion bar 14 that connects the input shaft 13 and the output shaft 15.

[0021] The rack shaft 12 is an axial member extending in the left-right direction of the vehicle, and is connected to the wheels 2 via tie rods 5 and knuckle arms 4 .

[0022] The output shaft 15 and the rack shaft 12 are connected to each other via a rack-and-pinion mechanism including a first pinion gear 16 provided at an end of the output shaft 15 and a rack gear 12a provided on the rack shaft 12. The torque of the output shaft 15 is converted into an axial load of the rack shaft 12 via the first pinion gear 16 and the rack gear 12a, which mesh with each other, and is transmitted to the rack shaft 12. As a result, the rack shaft 12 is displaced in the axial direction, and steers the wheels 2 via the tie rod 5. In addition, the rack shaft 12 is biased toward the first pinion gear 16 by a biasing mechanism 17 (see FIG. 2). As a result, backlash between the rack gear 12a and the first pinion gear 16 is reduced, and the teeth rattle noise generated when the rack shaft 12 is displaced is reduced.

[0023] The electric power steering device 100 includes an assist unit 20 that generates a steering assist torque by an electric motor 21. The assist unit 20 transmits the torque of the electric motor 21 to the rack shaft 12 independently of the output shaft 15, thereby assisting the steering operation of the driver. The assist unit 20 includes a drive shaft 22 that is rotationally driven by the electric motor 21, a second pinion gear 23 that is provided on the drive shaft 22 and rotates together with the drive shaft 22, and a speed reducer unit 50 that reduces the rotation of the electric motor 21 and transmits it to the drive shaft 22.

[0024] The speed reducer 50 is a worm gear mechanism including a worm shaft 51 driven by the electric motor 21 and a worm wheel 52 provided on the drive shaft 22. The worm shaft 51 and the worm wheel 52, and the second pinion gear 23 and the rack gear 12a are meshed with each other. The torque of the electric motor 21 is transmitted to the rack shaft 12 via the worm shaft 51, the worm wheel 52, the drive shaft 22, the second pinion gear 23, and the rack gear 12a.

[0025] The electric power steering device 100 includes a torque sensor 40 that detects the torque acting on the torsion bar 14, and a controller 30 that controls the drive of the electric motor 21 in accordance with the detection value of the torque sensor 40. The controller 30 calculates the torque to be output by the electric motor 21 based on the output signal from the torque sensor 40, and controls the drive of the electric motor 21 so as to generate the calculated torque.

[0026] In this manner, in the electric power steering device 100 configured as described above, the steering torque applied to the input shaft 13 is detected by the torque sensor 40, and based on the detection result, the controller 30 controls the drive of the electric motor 21, thereby assisting the driver's steering operation.

[0027] As shown in FIG. 2, the electric power steering device 100 includes a housing 60 that accommodates the steering shaft 11 and the rack shaft 12.

[0028] The housing 60 is formed of a metal such as aluminum. The housing 60 includes a rack housing 70 that accommodates the rack shaft 12, the biasing mechanism 17, etc., and a handle-side housing 80 that is fastened to the rack housing 70 via a bolt 61. A part of the input shaft 13, a part of the torsion bar 14, a part of the output shaft 15, and the torque sensor 40 are accommodated in an accommodating portion 81 that is a space within the handle-side housing 80. The input shaft 13 and the output shaft 15 are rotatably supported by the handle-side housing 80 via a bearing 62 and a bearing 63, respectively. A seal member 90 that seals between the outer circumferential surface of the output shaft 15 of the steering shaft 11 and the inner circumferential surface of the accommodating portion 81 of the handle-side housing 80 is provided between the outer circumferential surface of the output shaft 15 of the steering shaft 11 and the inner circumferential surface of the accommodating portion 81 of the handle-side housing 80.

[0029] The seal member 90 is intended to prevent foreign matter such as water from entering the handle side housing 80 from the rack housing 70, and to protect electrical components such as the torque sensor 40 in the handle side housing 80. As shown in Fig. 3, the seal member 90 includes an annular main body 91 provided between the outer circumferential surface of the output shaft 15 and the inner circumferential surface of the accommodating portion 81, and a filter 99 that is permeable to gas but not to liquid.

[0030] The main body portion 91 has an annular core portion 92 (see FIGS. 4 and 5) made of metal, and an annular seal portion 95 (FIGS. 3 and 5) in which the core portion 92 is provided.

[0031] As shown in Fig. 4 to Fig. 6, the core metal part 92 has a flat, annular flat part 92a and a cylindrical part 92b formed by extending in the axial direction from a radially outer end of the flat part 92a. In other words, the core metal part 92 has a shape in which the boundary between the flat part 92a and the cylindrical part 92b is bent at a substantially right angle. The core metal part 92 is formed with a first ventilation part 97a. The first ventilation part 97a is a through hole penetrating the flat part 92a in the axial direction, and a plurality of the first ventilation parts 97a are formed at equal intervals in the circumferential direction (see Fig. 4). In Fig. 3, the first ventilation part 97a is hidden by the filter 99 and is indicated by a dotted line. A plurality of the first ventilation parts 97a may be formed at different intervals in the circumferential direction.

[0032] The seal portion 95 is formed of, for example, resin. As shown in FIG. 3, FIG. 5, and FIG. 6, the seal portion 95 has an annular inner seal portion 95a provided on the radially inner side, an annular outer seal portion 95b provided on the radially outer side, and an annular connection portion 95c provided between the upper end of the inner seal portion 95a and the upper end of the outer seal portion 95b in FIG. 3, FIG. 5, and FIG. 6. The inner seal portion 95a is formed to extend in the axial direction, and the inner circumferential surface is formed to bulge radially inward. The outer seal portion 95b is formed to extend in the axial direction, and the boundary between the flat plate portion 92a and the cylindrical portion 92b of the core metal portion 92 and the cylindrical portion 92b are provided inside. The connection portion 95c is provided with the inner end and the outer end of the flat plate portion 92a of the core metal portion 92. The connection portion 95c is formed with a second ventilation portion 97b as a through hole that penetrates the connection portion 95c in the axial direction. The second ventilation portion 97b is formed in an annular shape, and the flat portion 92a of the core metal portion 92 is provided such that an area corresponding to the second ventilation portion 97b is not covered by the connecting portion 95c. The seal member 90 is attached by pressing the inner seal portion 95a against the outer circumferential surface of the output shaft 15 with an annular member 98 such as a snap ring. When the seal member 90 is attached between the outer circumferential surface of the output shaft 15 and the inner circumferential surface of the accommodating portion 81, the inner circumferential surface of the inner seal portion 95a comes into close contact with the outer circumferential surface of the output shaft 15, and the outer circumferential surface of the outer seal portion 95b comes into close contact with the inner circumferential surface of the accommodating portion 81.

[0033] The first ventilation portion 97a and the second ventilation portion 97b communicate with each other. The first ventilation portion 97a and the second ventilation portion 97b form a ventilation portion 97 that penetrates the main body portion 91 in the axial direction. Even when the seal member 90 is provided between the outer circumferential surface of the output shaft 15 and the inner circumferential surface of the accommodation portion 81, the space on the front side (handle-side housing 80 side) of the seal member 90 communicates with the space on the back side (rack housing 70 side) through the first ventilation portion 97a and the second ventilation portion 97b. Note that the second ventilation portion 97b does not have to be formed in an annular shape, and may be formed in a plurality of parts at equal intervals in the circumferential direction corresponding to the first ventilation portion 97a.

[0034] The filter 99 is a waterproof moisture-permeable film made of, for example, polytetrafluoroethylene (PTFE). As shown in FIG. 3, the filter 99 is formed in an annular shape and provided in the ventilation portion 97. Specifically, the filter 99 is provided to cover the opening of the first ventilation portion 97a formed in the flat plate portion 92a of the core metal portion 92. The filter 99 is provided to cover each opening of the first ventilation portions 97a. As shown in FIG. 6, the inner peripheral edge 99a of the filter 99 is sandwiched between the inner peripheral side of the connection portion 95c and the flat plate portion 92a, and the outer peripheral edge 99b of the filter 99 is sandwiched between the outer peripheral side of the connection portion 95c and the flat plate portion 92a. This allows the filter 99 to be easily positioned in the axial direction. The core metal portion 92, the seal portion 95, and the filter 99 are integrally molded by insert molding, for example, with the filter 99 and the core metal portion 92 positioned by a mold. The filter 99 allows gas to pass through the first ventilation portion 97a and the second ventilation portion 97b, but does not allow liquid to pass through them. Therefore, the seal member 90 blocks the movement of liquid between the outer circumferential surface of the output shaft 15 and the inner circumferential surface of the accommodating portion 81. As a result, even if a foreign object such as water enters the rack housing 70 due to damage to a boot (not shown) covering the rack shaft 12, the foreign object is prevented from entering the handle side housing 80, and electrical components such as the torque sensor 40 in the handle side housing 80 are protected.

[0035] Here, a leak test is performed on the electric power steering device 100 before shipment. In the leak test, the housing 60 is filled with gas and the airtightness is inspected. If the seal member 90 is configured to seal both liquid and gas, the entire housing 60 cannot be filled with gas at once when performing the leak test, and it is necessary to fill the rack housing 70 and the handle-side housing 80 with gas separately. In other words, the provision of the seal member 90 makes the leak test more time-consuming.

[0036] In contrast to this, in the seal member 90 of this embodiment, a filter 99 that is permeable to gas but not permeable to liquid is provided in the ventilation section 97 of the main body section 91. Therefore, the seal member 90 seals the gap between the outer circumferential surface of the output shaft 15 and the inner circumferential surface of the accommodation section 81 so that gas can pass through but liquid cannot. Therefore, when one of the rack housing 70 and the handle side housing 80 is filled with gas during a leak test, the other is also filled with gas, so there is no need to fill both the rack housing 70 and the handle side housing 80 with gas. This eliminates the effect of the seal member 90 on the leak test that is performed by filling with gas.

[0037] Furthermore, a plurality of ventilation sections 97 are formed at intervals in the circumferential direction of the main body 91. As a result, even if one of the ventilation sections 97 is blocked by a foreign object or the like, gas can pass through the other ventilation sections 97. Furthermore, since the plurality of ventilation sections 97 ventilate between the rack housing 70 and the handle side housing 80, the size of each of the ventilation sections 97 can be made small. As a result, even if the filter 99 has low rigidity, the filter 99 can be provided in the ventilation section 97 without causing a large dent.

[0038] Furthermore, in this embodiment, the filter 99 is provided on the handle-side housing 80 side of the ventilation section 97 (upper side in Figs. 2, 3 and 5). This prevents the filter 99 from becoming dirty and clogged with lubricating oil or the like in the rack housing 70. The filter 99 may also be provided on the rack housing 70 side of the ventilation section 97 (lower side in Figs. 2, 3 and 5). In this case, the filter 99 is prevented from becoming dirty and clogged with lubricating oil or the like from the adjacent bearing 63.

[0039] According to the present embodiment described above, the following advantageous effects are obtained.

[0040] In the seal member 90, a filter 99 that is permeable to gas but not permeable to liquid is provided in the ventilation section 97 of the main body 91. Therefore, the seal member 90 seals the gap between the outer circumferential surface of the output shaft 15 and the inner circumferential surface of the housing section 81 so that gas can pass through but liquid cannot. This makes it possible to eliminate the effect of the seal member 90 on a leak test that is performed by filling the space with gas.

[0041] Next, modified examples of the present embodiment will be described. The following modified examples are also within the scope of the present invention, and it is possible to combine the following modified examples with each of the configurations of the above embodiment, or to combine the following modified examples with each other.

[0042] <Variation 1> In the above embodiment, the main body 91 of the seal member 90 has an annular core portion 92 having a flat plate portion 92a and a cylindrical portion 92b, and an annular seal portion 95 having an inner seal portion 95a, an outer seal portion 95b, and a connecting portion 95c. However, the configuration of the core portion 92 and the seal portion 95 is not limited to the above, and the main body 91 does not have to have the core portion 92. The main body 91 may have any configuration as long as it is provided at least between the outer circumferential surface of the output shaft 15 and the inner circumferential surface of the housing portion 81 to seal between them, and has a ventilation portion 97 that penetrates the main body 91 in the axial direction.

[0043] <Variation 2> In the above embodiment, a plurality of ventilation parts 97 are formed at intervals in the circumferential direction of the main body part 91. However, the present invention is not limited to this, and only one ventilation part 97 may be formed in the main body part 91. Even with this configuration, the same effects as those of the above embodiment are achieved.

[0044] <Variation 3> In the above embodiment, the filter 99 is formed in an annular shape and provided in the ventilation portion 97, with one filter 99 provided to cover each opening of the multiple first ventilation portions 97a. However, the present invention is not limited to this, and the filters 99 may be formed in a circular shape, for example, and multiple filters 99 may be provided so that one filter 99 covers the opening of one first ventilation portion 97a.

[0045] <Modification 4> In the above embodiment, the filter 99 is positioned in the axial direction by having the inner peripheral edge 99a sandwiched between the connecting portion 95c and the flat plate portion 92a, and the outer peripheral edge 99b sandwiched between the connecting portion 95c and the flat plate portion 92a. For example, as shown in FIG. 7, the core metal portion 92 may be formed with a positioning portion 92c that engages with the filter 99 to position the filter 99, and the filter 99 may be positioned by the positioning portion 92c. The positioning portion 92c is formed so as to protrude in the axial direction from the flat plate portion 92a toward the filter 99. The positioning portion 92c is formed in a triangular shape and engages with a notch (not shown) formed in the filter 99. This allows the filter 99 to be positioned in the circumferential direction with a simple configuration. The positioning portion 92c may also be formed in a wall shape at the inner end of the flat plate portion 92a. In this case, the positioning portion 92c engages with the inner peripheral surface of the annular filter 99. This allows the filter 99 to be positioned in the radial direction with a simple configuration.

[0046] <Variation 5> In the above embodiment, the seal member 90 is provided in the electric power steering device 100. However, the present invention is not limited to this, and the seal member 90 may be provided in other equipment that is filled with gas to perform a leak test.

[0047] The configuration, operation, and effects of the embodiment of the present invention configured as above will be described below.

[0048] A sealing member 90 that seals between the outer peripheral surface of the steering shaft 11 as a shaft and the inner peripheral surface of the accommodation portion 81 in which the steering shaft 11 is accommodated comprises an annular main body portion 91 provided between the outer peripheral surface of the steering shaft 11 and the inner peripheral surface of the accommodation portion 81, and a filter 99 that is permeable to gas but not to liquid, and a ventilation portion 97 that penetrates the main body portion 91 in the axial direction is formed in the main body portion 91, and the filter 99 is provided in the ventilation portion 97.

[0049] In this configuration, a filter 99 that is permeable to gas but not to liquid is provided in the ventilation portion 97 of the main body 91 of the seal member 90. Therefore, the seal member 90 seals the gap between the outer circumferential surface of the steering shaft 11 and the inner circumferential surface of the housing portion 81 so that gas can pass through but liquid cannot. This eliminates the effect of the seal member 90 on a leak test that is performed by filling the gap with gas.

[0050] The main body 91 also has an annular core portion 92 made of metal and an annular seal portion 95 in which the core portion 92 is provided, and the ventilation portion 97 is formed in the core portion 92 and the seal portion 95.

[0051] Further, a plurality of ventilation portions 97 are formed at intervals in the circumferential direction of the main body portion 91 .

[0052] In these configurations, even if one of the ventilation parts 97 becomes blocked by a foreign object or the like, gas can still pass through the other ventilation parts 97.

[0053] Further, the filter 99 is provided so as to cover the opening of the ventilation portion 97 (first ventilation portion 97a) formed in the core metal portion 92, and the core metal portion 92 is formed with a positioning portion 92c that engages with the filter 99 to position the filter 99.

[0054] In this configuration, the filter 99 can be easily positioned by the positioning portion 92c.

[0055] The filter 99 is provided to cover the opening of the ventilation portion 97 (first ventilation portion 97a) formed in the core portion 92, and edges (99a, 99b) of the filter 99 are sandwiched between the seal portion 95 and the core portion 92.

[0056] In this configuration, the edges (99a, 99b) of the filter 99 are sandwiched between the seal portion 95 and the core metal portion 92, so that the filter 99 can be easily positioned in the axial direction.

[0057] Although the embodiments of the present invention have been described above, the above-mentioned embodiments merely show some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above-mentioned embodiments. [Explanation of symbols]

[0058] 11... steering shaft (shaft), 81... accommodation portion, 90... seal member, 91... main body portion, 92... core metal portion, 92c... positioning portion, 95... seal portion, 97... ventilation portion, 99... filter, 99a... inner peripheral edge (edge ​​portion), 99b... outer peripheral edge (edge ​​portion)

Claims

1. A seal member that seals between an outer circumferential surface of a shaft and an inner circumferential surface of a housing portion in which the shaft is housed, an annular main body portion provided between the outer circumferential surface of the shaft and the inner circumferential surface of the housing portion; a filter that is permeable to gas but impermeable to liquid; The main body portion is formed with a ventilation portion penetrating the main body portion in the axial direction, The filter is provided in the ventilation portion.

2. The seal member according to claim 1 , the main body portion has an annular core portion formed of metal and an annular seal portion in which the core portion is provided, The sealing member, wherein the ventilation portion is formed in the core metal portion and the seal portion.

3. The seal member according to claim 1 , The sealing member is characterized in that a plurality of the ventilation portions are formed at intervals in the circumferential direction of the main body portion.

4. The seal member according to claim 2, the filter is provided to cover an opening of the ventilation portion formed in the core metal portion, A seal member, wherein the core metal portion is formed with a positioning portion for engaging with the filter to position the filter.

5. The seal member according to claim 2, the filter is provided to cover an opening of the ventilation portion formed in the core metal portion, A seal member, wherein an edge portion of the filter is sandwiched between the seal portion and the core metal portion.

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