JP2019158006A - Seal ring for cross shaft joint, cross shaft joint and steering device - Google Patents

Abstract

To provide a seal ring for a cross shaft joint which can prevent the lowering of seal performance caused by baking while suppressing a friction force generated between seal lips and a bearing cup, the cross shaft joint and a steering device.SOLUTION: A seal ring for a cross joint has an annular core member 30 and an elastic member 40 fastened to the core member 30, and the elastic member 40 extends to a radial bearing 21 side over the whole periphery from the core member 30 side between a stepped face 17a and the radial bearing 21. A plurality of pieces of seal lips are formed whose lengths in a center axial line direction are not shorter than three times of a thickness of an intermediate part in the center axial line direction in a radial direction.SELECTED DRAWING: Figure 4

Description

  The present application relates to a seal ring used for a cross joint that connects an intermediate shaft that transmits a steering force of a steering device, a cross joint that includes the seal ring, and a steering device that includes the cross joint.

  2. Description of the Related Art Conventionally, there is a seal ring that seals a gap formed between a bearing cup of a radial bearing that is externally fitted to an end portion of a cross shaft constituting a cross shaft joint and a shaft portion of the cross shaft. Such a seal ring has an elastic seal part and a reinforcing ring embedded in the elastic seal part as in Patent Documents 1 and 2 below.

  The cross shaft joint is used, for example, for coupling an intermediate shaft of a steering apparatus for an automobile. The intermediate shaft and the cross joint are mainly made of a metal material. However, there is an area where salt is applied to the road to prevent freezing of the road in winter, and the salt promotes corrosion of the metal. For this reason, the request | requirement of the antirust performance of the intermediate shaft and cross shaft coupling arrange | positioned out of a vehicle compartment in the area where salt is applied to a road is high.

  When the anti-rust treatment is applied to the parts that make up the intermediate shaft and cross shaft joint, the dispersion of the anti-rust film increases, making it difficult to maintain and manage the required finished product performance. It is done. Currently, such surface treatment is mainly performed by painting, and after coating, drying at a temperature of about 100 ° C. is performed.

  However, in order to further enhance the rust prevention performance, it is preferable to perform baking at a higher temperature. In addition, zinc-nickel (ZnNi) alloy plating, which has recently been increasingly used for metal parts outside the passenger compartment as having high anti-rust performance, has a temperature of about 200 ° C. in order to prevent hydrogen embrittlement after plating. It is necessary to perform baking.

Utility Model Registration No. 3041732 Japanese Patent Laid-Open No. 9-151956

  When baking is performed at a temperature of about 200 ° C., the dimensions of the elastic seal portion that constitutes the seal ring change, and the fastening performance may be reduced, thereby reducing the sealing performance.

  In order to prevent deterioration of the sealing performance, it is conceivable to strongly press the sealing lip against the bearing cup. However, in this case, the frictional force between the seal lip and the bearing cup is increased, the operation of the steering wheel is heavy, and the operation feeling such as an automatic return failure of the steering wheel after the steering is deteriorated.

  In view of the above, an object of the present invention is to provide a seal ring, a cross joint, and a steering device that can prevent a reduction in seal performance due to baking while suppressing a frictional force generated between a seal lip and a bearing cup. And

In order to solve the above-described problem, the present application has a central portion and four shaft portions extending from the central portion, and the central portion extends radially outward from the proximal end of the shaft portion. Used with a cross axis that forms a step surface,
A seal ring for a cross shaft joint that is externally fitted to the shaft portion between a radial bearing attached to a tip portion of the shaft portion and the stepped surface,
An annular core member;
An elastic member fixed to the core member;
The elastic member extends from the core member side to the radial bearing side over the entire circumference between the step surface and the radial bearing, and the length in the central axis direction is the radial direction of the intermediate portion in the central axis direction There is provided a seal ring for a cross shaft joint, wherein a plurality of seal lips that are three times or more the thickness of the seal shaft are formed.

  Preferably, the plurality of seal lips have an inner diameter and an outer diameter that increase as they approach the radial bearing in the central axis direction.

Also preferably, the plurality of seal lips are
A seal lip having a smaller inner diameter and outer diameter as it approaches the radial bearing in the central axis direction;
And a seal lip which is disposed on the radially outer side of the seal lip having a smaller inner diameter and outer diameter, and has an inner diameter and an outer diameter that increase as it approaches the radial bearing.

  Preferably, the plurality of seal lips are curved radially outward.

Also preferably, the plurality of seal lips are
A seal lip curved radially inward over the entire circumference;
A seal lip that is disposed radially outward of the seal lip curved radially inward and curved radially outward over the entire circumference.

Preferably, the core member is
An annular bottom that contacts the stepped surface through the shaft on the inside;
From the bottom, over the entire circumference, an upright portion extending toward the radial bearing in the central axis direction;
A second bottom portion having a hole extending radially outward from the end of the raised portion on the radial bearing side in the central axis direction and penetrating in the central axis direction;
From the second bottom part, extending to the radial bearing side in the central axis direction over the entire circumference, and a surrounding part surrounding the elastic member from the outside in the radial direction,
The elastic member has a seal lip protruding from the second bottom portion toward the center portion in the center axis direction over the entire circumference.

  Moreover, in order to solve the said subject, this application provides the cross shaft coupling provided with the said seal ring.

  Moreover, in order to solve the said subject, this application provides the steering device characterized by providing the said cross shaft coupling.

  According to the present invention, it is possible to provide a cross shaft joint seal ring, a cross shaft joint, and a steering device that can prevent a reduction in sealing performance due to baking while suppressing a frictional force generated between a seal lip and a bearing cup. it can.

FIG. 1 is a side view showing a steering device common to the embodiments of the present application. FIG. 2 is a perspective view showing an intermediate shaft and a cross joint common to the embodiments of the present application. FIG. 3 is a cross-sectional view showing a cross shaft, a radial bearing, and a seal ring according to an embodiment of the present application. FIG. 4 is an enlarged cross-sectional view of the seal ring according to the first embodiment of the present application. FIG. 5 is a cross-sectional view showing the periphery of the seal ring according to the first embodiment of the present application. 5A shows a case where the radial bearing is attached to the tip side of the shaft portion of the cross shaft from the reference position, and FIG. 5B shows a case where the radial bearing is attached to the reference position with respect to the shaft portion of the cross shaft. In this case, FIG. 5C shows a case where the radial bearing is attached to the base side with respect to the shaft portion of the cross shaft from the reference position. FIG. 6 is a sectional view showing the periphery of the seal ring according to the second embodiment of the present application. 6A shows a case where the radial bearing is attached to the tip side of the shaft portion of the cross shaft from the reference position, and FIG. 6B shows a case where the radial bearing is attached to the reference position with respect to the shaft portion of the cross shaft. In this case, FIG. 6C shows a case where the radial bearing is attached to the base side of the reference position with respect to the shaft portion of the cross shaft. FIG. 7 is an enlarged cross-sectional view of a seal ring according to a third embodiment of the present application. FIG. 8 is an enlarged cross-sectional view of a seal ring according to a fourth embodiment of the present application. FIG. 9 is an enlarged cross-sectional view of a seal ring according to a fifth embodiment of the present application.

  Hereinafter, embodiments of the present application will be described with reference to the drawings. In the present application, “the direction of the central axis” means the direction of the central axis of the seal ring unless otherwise specified. FIG. 1 is a side view showing a steering device 100 according to an embodiment of the present application.

  As shown in FIG. 1, the steering device 100 includes a steering wheel 1, a steering shaft 2, a steering column 3, a vehicle body side bracket 4, a first cross shaft joint 5, an intermediate shaft 6, and a second shaft. A cross shaft joint 7, a pinion gear 8, and a rack shaft 9 are provided. The steering wheel 1 is fixed to a steering shaft 2 that transmits the rotation. The steering shaft 2 passes through the inside of the steering column 3 and is supported by the steering column 3 so as to be rotatable about the central axis of the steering shaft 2. The steering column 3 is attached to the vehicle body 200 by the vehicle body side bracket 4. The rotation of the steering shaft 2 is transmitted to the intermediate shaft 6 by the first cross joint 5. The rotation of the intermediate shaft 6 is transmitted to the pinion gear 8 by the second cross joint 7. The pinion gear 8 rotates to move the rack shaft 9 in the vehicle width direction. The rack shaft 9 moves a knuckle arm (not shown) via a tie rod (not shown) to steer a front wheel (not shown).

  FIG. 2 is a perspective view showing the intermediate shaft 6, the first cross shaft joint 5, and the second cross shaft joint 7 according to the embodiment of the present application.

  The first cross shaft joint 5 includes a first yoke 11 and a second yoke 12. The second cross shaft joint 7 includes a third yoke 13 and a fourth yoke 14. The first yoke 11 has a pair of arms 11a formed in a bifurcated shape. The second yoke 12 has a pair of arms 12a formed in a bifurcated shape. The first yoke 11 and the second yoke 12 are connected via a pair of arms 11a and a cross shaft 16 (described later) held by the pair of arms 12a. Similarly, the third yoke 13 and the fourth yoke 14 are also connected by a pair of arms 13a and a cross shaft 16 (described later) held by the pair of arms 14a.

(First embodiment)
FIG. 3 is a cross-sectional view of the cross shaft 16, the radial bearing 21, and the seal ring 26 according to the first embodiment of the present application. A cross section cut in a direction perpendicular to the central axis of the intermediate shaft 6 is shown.

  The cross shaft 16 includes a center portion 17 and four columnar shaft portions 18 extending from the center portion 17 in four directions. Specifically, the cross shaft 16 includes a first shaft portion 18 that extends in one direction from the center portion 17, and the first shaft portion 18 and the first shaft portion 18 that share a central axis with the first shaft portion 18. Is a second shaft portion 18 extending to the opposite side, a third shaft portion 18 extending from the center portion 17 in a direction perpendicular to the first and second shaft portions 18, and a center of the third shaft portion 18. It has a fourth shaft portion 18 extending from the center portion 17 to the opposite side to the third shaft portion 18 with a common axis. Since the configuration around the shaft portion 18 is common to the four shaft portions 18, only one location will be described, and description of the configuration around the other shaft portion 18 will be omitted.

  A radial bearing 21 is fitted on the distal end portion of the shaft portion 18. As the radial bearing 21, a needle bearing can be used. The radial bearing 21 includes a bearing cup 22 and a roller 23. The bearing cup 22 is fitted in a circular hole formed in the pair of arms 11a to 14a of the yokes 11 to 14 described above. A plurality of rollers 23 are arranged in the circumferential direction between the bearing cup 22 and the shaft portion 18 of the cross shaft 16 in a direction substantially parallel to the shaft portion 18.

  A seal ring 26 is fitted on the base portion of the shaft portion 18. The central portion 17 of the cross shaft 16 has a dimension larger than that of the shaft portion 18 in the radial direction of the shaft portion 18, and forms a step surface 17 a that spreads radially outward from the base end of the shaft portion 18. Yes. The step surface 17 a is disposed substantially perpendicular to the central axis of the shaft portion 18. The seal ring 26 is in contact with the bearing cup 22 and the stepped surface 17a and prevents foreign matters such as muddy water from entering the bearing cup 22. The seal ring 26 may not be provided in the cross shaft joint provided in the vehicle interior, like the first cross shaft joint 5 shown in FIG.

  An insertion hole 18a is drilled in the central portion of the shaft portion 18 from the distal end side toward the base side. A synthetic resin pin 24 is inserted inside the insertion hole 18a. The pin 24 is interposed between the bearing cup 22 and the shaft portion 18 to prevent the bearing cup 22 from moving to the base side of the shaft portion 18. As a result, it is possible to prevent the seal ring 26 from being excessively compressed by the bearing cup 22 and impairing the sealing performance.

  FIG. 4 is an enlarged cross-sectional view of the seal ring 26 according to the first embodiment. FIG. 4 shows a cross section of the seal ring 26 cut along the central axis direction and the radial direction. The seal ring 26 has the same cross-sectional shape over the entire circumference.

  The seal ring 26 includes a core member 30 and an elastic member 40. The core member 30 has an annular shape. The elastic member 40 is made of an elastomer and is fixed to the core member 30. The elastic member 40 is also annular.

  The core member 30 protrudes radially outward from the outer periphery of the cylindrical portion 32 that is cylindrical on the inner diameter side and the cylindrical portion 32 on the center portion 17 side (lower side in FIG. 4) of the cross shaft 16 in the central axis direction. A bottom portion 31. The bottom 31 has an annular shape extending in a direction perpendicular to the central axis, and comes into surface contact with the stepped surface 17 a when assembled to the cross shaft 16. The core member 30 can be formed from a metal or an engineering plastic excellent in heat resistance.

  The elastic member 40 has a cross-sectional shape shown in FIG. 4 in a natural state where the elastic member 40 is not attached to the cross shaft 16. The elastic member 40 includes a main body 40 a, a first seal lip 41, a second seal lip 42, a third seal lip 43, and a fourth seal lip 44. The main body 40a of the elastic member 40 is fixed to the surface of the core member 30 excluding the surface of the bottom portion 31 on the center portion 17 side of the cross shaft 16 in the central axis direction.

  FIG. 5 is a cross-sectional view showing the periphery of the seal ring 26 according to the first embodiment of the present application. 5A shows a case where the radial bearing 21 is attached to the distal end side of the shaft portion 18 of the cross shaft 16 with respect to the reference position, and FIG. When attached to the reference position, FIG. 5C shows a case where the radial bearing 21 is attached to the base side with respect to the shaft portion 18 of the cross shaft 16 from the reference position.

  The main body 40a of the elastic member 40 extends from the core member 30 toward the radial bearing 21 side (upper side in FIG. 5) and radially outward in the central axis direction over the entire circumference. The first seal lip 41 protrudes radially inward over the entire circumference from the portion of the main body 40a located closest to the radial bearing 21 in the central axis direction. As shown in FIG. 5, the first seal lip 41 is pressed against the outer peripheral surface of the bearing cup 22 of the radial bearing 21.

  The second seal lip 42 projects radially inward from the portion of the main body 40a near the first seal lip 41 between the core member 30 and the first seal lip 41. The second seal lip 42 has a conical surface shape inclined with respect to the central axis so that the inner diameter and the outer diameter become smaller toward the radial bearing 21 in the central axis direction. As shown in FIG. 5, the second seal lip 42 is pressed against the outer peripheral surface of the bearing cup 22 of the radial bearing 21.

  The third seal lip 43 protrudes from the portion of the main body 40a on the radial bearing 21 side of the core member 30 in the central axis direction to the radial bearing 21 side over the entire circumference. The third seal lip 43 has a conical surface shape inclined with respect to the central axis of the shaft portion 18 so that the inner diameter and the outer diameter become larger toward the radial bearing 21 side in the central axis direction. As shown in FIG. 5, the third seal lip 43 contacts the inner curved portion 22 a of the bearing cup 22.

  The fourth seal lip 44 has the same center axis as the third seal lip 43, but has a smaller diameter than the third seal lip 43 and is disposed on the radially inner side of the third seal lip 43. . The fourth seal lip 44 has a conical surface shape inclined with respect to the central axis so that the inner diameter and the outer diameter increase from the main body 40a toward the radial bearing 21 in the central axis direction. The inclination angle of the fourth seal lip 44 with respect to the central axis is smaller than the inclination angle of the third seal lip 43 with respect to the central axis. The fourth seal lip 44 contacts the inner curved portion 22a of the bearing cup 22 as shown in FIGS. 5 (b) and 5 (c).

  The third seal lip 43 extends longer toward the radial bearing 21 than the fourth seal lip 44 in the central axis direction. As shown in FIG. 5 (b), when the radial bearing 21 is attached to the reference position with respect to the shaft portion 18 of the cross shaft 16, the third and fourth seal lips 43, 44 are curved inside the bearing cup 22. It is pressed against the portion 22a and elastically deforms.

  When the radial bearing 21 is disposed on the tip side of the cross shaft 16 with respect to the reference position shown in FIG. 5B, the third seal lip 43 of the bearing cup 22 is provided as shown in FIG. The fourth sealing lip 44 comes into contact with the inner curved portion 22 a and is not in contact with the inner curved portion 22 a of the bearing cup 22. Even in this state, the seal ring 26 can exhibit a desired sealing performance.

  When the radial bearing 21 is attached to the cross shaft 16, when the radial bearing 21 is attached to the center 17 side of the cross shaft 16 from the reference position shown in FIG. 5B, as shown in FIG. 5C. In addition, the third and fourth seal lips 43, 44 are elastically deformed to a greater extent than when arranged at the reference position, and are pressed against the inner curved portion 22 a of the bearing cup 22. Even in this state, the seal ring 26 can exhibit a desired sealing performance.

  The third and fourth seal lips 43 and 44 extend toward the radial bearing 21 with a length in the central axis direction that is three times or more the thickness of the intermediate portion in the central axis direction. As a result, the third and fourth seal lips 43 and 44 have low rigidity, and an increase in frictional force due to assembly errors can be suppressed.

  According to the first embodiment, there are provided a cross shaft joint seal ring, a cross shaft joint, and a steering device that can prevent a reduction in seal performance due to baking while suppressing a frictional force generated between a seal lip and a bearing cup. can do.

(Second Embodiment)
Next, a second embodiment of the present application will be described with reference to FIG. FIG. 6 is a cross-sectional view showing the periphery of the seal ring 226 of the second embodiment of the present application. 6A shows the case where the radial bearing 221 is attached to the tip side of the shaft portion 218 of the cross shaft from the reference position, and FIG. 6B shows the reference position of the radial bearing 221 relative to the shaft portion 218 of the cross shaft. 6C shows the case where the radial bearing 221 is attached to the base side of the reference position with respect to the shaft portion 218 of the cross shaft.

  Since the second embodiment is common in many respects to the first embodiment, differences from the first embodiment will be mainly described here. The parts of the second embodiment corresponding to the parts to which reference numerals are attached in the first embodiment are given reference numerals made up of the numerals of the reference numerals used in the first embodiment plus “200”. To do. For example, “241” is given to the first seal lip of the second embodiment corresponding to the first seal lip 41 of the first embodiment.

  In the second embodiment, the fourth seal lip 244 is inclined with respect to the central axis so that the inner diameter and the outer diameter decrease from the main body 240a of the elastic member 240 toward the radial bearing 221 in the central axis. It has a conical surface shape. Accordingly, as shown in FIGS. 6B and 6C, when the third and fourth seal lips 243 and 244 are pressed against the inner curved portion 222a of the radial bearing 221, they are separated from each other. Elastically deforms.

  The third and fourth seal lips 243 and 244 extend to the radial bearing 221 side with a length in the central axis direction that is three times or more the thickness of the intermediate portion in the central axis direction. As a result, the third and fourth seal lips 243 and 244 have low rigidity, and an increase in frictional force due to assembly errors can be suppressed.

  According to the second embodiment, as in the first embodiment, the cross shaft seal ring that can prevent the deterioration of the sealing performance due to baking while suppressing the frictional force generated between the seal lip and the bearing cup, A cross shaft joint and a steering device can be provided.

(Third embodiment)
Next, a third embodiment of the present application will be described with reference to FIG. FIG. 7 is an enlarged cross-sectional view of the seal ring 326 according to the third embodiment. Since the third embodiment is common in many respects to the first embodiment, differences from the first embodiment will be mainly described here. The parts of the third embodiment corresponding to the parts to which reference numerals are attached in the first embodiment are given reference numerals made up of the numerals of the reference numerals used in the first embodiment plus “300”. To do. For example, “341” is attached to the first seal lip of the third embodiment corresponding to the first seal lip 41 of the first embodiment.

  The third embodiment is different from the first embodiment in that the core member 330 has a configuration and a fifth seal lip 345.

  The core member 330 includes a first tubular portion 332, a bottom portion 331, an upright portion 333, a second bottom portion 334, an inclined portion 335, and a second tubular portion 336. The upright portion 333 has a cylindrical shape extending from the outer edge of the bottom portion 331 of the core member 330 to the radial bearing side (upper side in FIG. 7) in the central axis direction. The second bottom portion 334 extends radially outward from the end on the radial bearing side of the upright portion 333 in the central axis direction. By comprising in this way, the 5th seal lip 345 can be formed. The inclined portion 335 and the second cylindrical portion 336 constitute an surrounding portion 330 a that surrounds the outer periphery of the elastic member 340. Further, the first seal lip 341 and the second seal lip 342 constitute a surrounding portion side seal lip fixed to the surrounding portion 330a.

  The fifth seal lip 345 projects from the second bottom 334 toward the center of the cross shaft over the entire circumference. The second bottom portion 334 is formed with a hole portion 334a penetrating in the central axis direction, so that the elastic member 340 portion disposed closer to the radial bearing than the second bottom portion 334 in the central axis direction, 5 seal lips 345 can be formed integrally. The fifth seal lip 345 is pressed against the stepped surface at the center of the cross shaft when the seal ring 326 is attached to the cross shaft.

  The third and fourth seal lips 343 and 344 extend to the radial bearing 321 side with a length in the central axis direction that is three times or more the thickness of the intermediate portion in the central axis direction. As a result, the third and fourth seal lips 343 and 344 have low rigidity, and an increase in frictional force due to assembly errors can be suppressed.

  According to the third embodiment, as in the first embodiment, the seal ring for a cross joint that can prevent the deterioration of the sealing performance due to baking while suppressing the frictional force generated between the seal lip and the bearing cup. A cross joint and a steering device can be provided. The material such as rubber forming the first and second seal lips 341 and 342 has a higher linear expansion coefficient than the material such as iron forming the bearing cup of the radial bearing. Therefore, in the configuration in which the core member 330 does not have the surrounding portion 330a, the first and second seal lips 341 and 342 expand in a direction of escaping from the bearing cup of the radial bearing due to the high temperature due to baking. On the other hand, when the surrounding portion 330a is provided as in the third embodiment, the first and second seal lips 341 and 342 having a large linear expansion coefficient are formed of iron, resin, or the like having a small linear expansion coefficient. It can be enclosed by the surrounding part 330a, can suppress expansion | swelling of the 1st, 2nd seal lip 341,342, and can prevent that sealing performance falls. Further, according to the third embodiment, by providing the fifth seal lip 345, the sealing performance between the core member 330 and the step surface of the cross shaft can be enhanced.

(Fourth embodiment)
Next, a fourth embodiment of the present application will be described with reference to FIG. FIG. 8 is an enlarged cross-sectional view of a seal ring 426 according to the fourth embodiment. Since the fourth embodiment is common to the first embodiment in many respects, differences from the first embodiment will be mainly described here. The parts of the fourth embodiment corresponding to the parts to which reference numerals are attached in the first embodiment are given reference numerals made up of the numerals of the reference numerals used in the first embodiment plus “400”. To do. For example, “441” is given to the first seal lip of the fourth embodiment corresponding to the first seal lip 41 of the first embodiment.

  The fourth embodiment is different from the first embodiment in that the third seal lip 443 and the fourth seal lip 444 are curved outward in the radial direction. As shown in FIG. 8, the third and fourth seal lips 443, 444 are curved so that the radially inner side is convex and the radially outer side is concave.

  The third and fourth seal lips 443 and 444 extend to the radial bearing 421 side with a length in the central axis direction that is three times or more the thickness of the intermediate portion in the central axis direction. As a result, the third and fourth seal lips 443 and 444 have low rigidity, and an increase in frictional force due to assembly errors can be suppressed.

  According to the fourth embodiment, as in the first embodiment, a seal ring for a cross shaft joint that can prevent a reduction in sealing performance due to baking while suppressing a frictional force generated between the seal lip and the bearing cup. A cross joint and a steering device can be provided. In addition, by bending the third and fourth seal lips 443 and 444, it becomes easy to elastically deform by contact with the radial bearing. Thereby, the change in the contact pressure between the radial bearing and the seal lip due to the difference in the position of the radial bearing can be reduced, and an increase in frictional force due to an assembly error can be prevented.

(Fifth embodiment)
Next, a fifth embodiment of the present application will be described with reference to FIG. FIG. 9 is an enlarged cross-sectional view of a seal ring 526 according to the fifth embodiment. Since the fifth embodiment is common to the first embodiment in many respects, differences from the first embodiment will be mainly described here. The parts of the fifth embodiment corresponding to the parts to which reference numerals are attached in the first embodiment are given reference numerals made up of the reference numerals used in the first embodiment plus “500”. To do. For example, “541” is attached to the first seal lip of the fifth embodiment corresponding to the first seal lip 41 of the first embodiment.

  The fifth embodiment is different from the first embodiment in that the third seal lip 543 is curved outward in the radial direction. The third seal lip 543 is curved so that the radially inner side is convex and the radially outer side is concave.

  Further, in the fifth embodiment, the fourth seal lip 544 has a smaller radial bearing side than the central side of the cross shaft in the central axis direction, and is curved inward in the radial direction. However, this is different from the first embodiment. The fourth seal lip 544 is curved so that the inner side in the radial direction is concave and the outer side in the radial direction is convex.

  The third and fourth seal lips 543 and 544 extend toward the radial bearing 521 with a length in the central axis direction that is three times or more the thickness of the intermediate portion in the central axis direction. As a result, the third and fourth seal lips 543 and 544 have low rigidity, and an increase in frictional force due to assembly errors can be suppressed.

  According to the fifth embodiment, as in the first embodiment, a seal ring for a cross shaft joint that can prevent a reduction in sealing performance due to baking while suppressing a frictional force generated between the seal lip and the bearing cup. A cross joint and a steering device can be provided. Further, by bending the third and fourth seal lips 543 and 544, it becomes easy to be elastically deformed by contact with the radial bearing. Thereby, the change in the contact pressure between the radial bearing and the seal lip due to the difference in the position of the radial bearing can be reduced, and an increase in frictional force due to an assembly error can be prevented.

  In addition, this invention is not limited to the said embodiment. For example, the number of seal lips in the seal ring is not limited to four or five, and may be one, two, three, six or more. If there are a plurality of seal lips disposed between the step surface of the cross shaft and the radial bearing, three or more seal lips may be provided.

  A part of each embodiment can be applied to other embodiments. For example, the core member 330 and the fifth seal ring 345 of the third embodiment can be applied to the second, fourth, and fifth embodiments.

DESCRIPTION OF SYMBOLS 1 Steering wheel 2 Steering shaft 3 Steering column 4 Car body side bracket 5 First cross shaft joint 6 Intermediate shaft 7 Second cross shaft joint 8 Pinion gear 9 Rack shaft 11 First yoke 12 Second yoke 13 Third Yoke 14 Fourth yoke 11a, 12a, 13a, 14a Pair of arms 16 Cross shaft 17 Center portion 17a Stepped surface 18, 218 Shaft portion 18a Insertion holes 21, 221 Radial bearing 22 Bearing cups 22a, 222a Inner curved portion 23 Roller 24 Pins 26, 226, 326, 426, 526 Seal rings 30, 230, 330, 430, 530 Core members 31, 231, 331, 431, 531 Bottom 32, 232, 332, 432, 532 Cylindrical portion 333 Upright portion 334 First 2 bottom part 334a hole part 335 inclined part 336 2nd cylindrical part 4 240, 340, 440, 540 Elastic member 40a, 240a, 340a, 440a, 540a Main body 41, 241, 341, 441, 541 First seal lip 42, 242, 342, 442, 542 Second seal lip 43, 243, 443, 543 Third seal lip 44, 244, 444, 544 Fourth seal lip 345 Fifth seal lip 100 Steering device 200 Car body

Claims (8)

It has a central portion and four shaft portions extending from the central portion, and the central portion is used together with a cross shaft that forms a stepped surface extending radially outward from the shaft portion from the base end of the shaft portion. ,
A seal ring for a cross shaft joint that is externally fitted to the shaft portion between a radial bearing attached to a tip portion of the shaft portion and the stepped surface,
An annular core member;
An elastic member fixed to the core member;
The elastic member extends from the core member side to the radial bearing side over the entire circumference between the step surface and the radial bearing, and the length in the central axis direction is the radial direction of the intermediate portion in the central axis direction A seal ring for a cross shaft joint, wherein a plurality of seal lips that are three times or more the thickness of the seal shaft are formed.   2. The cross shaft joint seal ring according to claim 1, wherein the plurality of seal lips have an inner diameter and an outer diameter that increase toward the radial bearing in a central axis direction. The plurality of seal lips are:
A seal lip having a smaller inner diameter and outer diameter as it approaches the radial bearing in the central axis direction;
2. The cross joint according to claim 1, further comprising: a seal lip that is disposed on a radially outer side of the seal lip in which the inner diameter and the outer diameter become smaller, and that increases in inner diameter and the outer diameter as approaching the radial bearing. Seal ring.   The seal ring for a cross shaft joint according to claim 1, wherein the plurality of seal lips are curved radially outward. The plurality of seal lips are:
A seal lip curved radially inward over the entire circumference;
The seal ring for a cross shaft joint according to claim 1, further comprising: a seal lip that is disposed radially outward of the seal lip curved radially inward and curved radially outward over the entire circumference. The core member is
An annular bottom that contacts the stepped surface through the shaft on the inside;
From the bottom, over the entire circumference, an upright portion extending toward the radial bearing in the central axis direction;
A second bottom portion having a hole extending radially outward from the end of the raised portion on the radial bearing side in the central axis direction and penetrating in the central axis direction;
From the second bottom part, extending to the radial bearing side in the central axis direction over the entire circumference, and a surrounding part surrounding the elastic member from the outside in the radial direction,
6. The cross according to claim 1, wherein the elastic member has a seal lip protruding from the second bottom portion toward the central portion in the central axis direction over the entire circumference. Seal ring for shaft coupling.   A cross shaft joint comprising the seal ring for a cross shaft joint according to any one of claims 1 to 6.   A steering apparatus comprising the cross joint according to claim 7.

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