JP2019100466A - Radial needle bearing and cross shaft type universal joint - Google Patents

Abstract

A cross shaft type universal joint in which a negative gap is set between a shaft portion and a needle is realized at a low cost. As a radial needle bearing 10b for rotatably supporting a shaft portion 23b constituting a cross shaft 9 inside a bearing hole 20a formed in an arm portion 12b constituting a yoke 8a, a bottomed cylindrical shape is provided. A bearing cup 26 and a hollow needle 27 having a bottom 33 on the distal end side of the shaft portion 23b and an opening 34 on the proximal end side of the shaft portion 23b are used. [Selection] Figure 5

Description

  The present invention relates to a cross shaft universal joint used for enabling rotational force transmission to be connected with rotation shafts not on the same straight line, and a radial needle bearing forming the cross shaft universal joint.

  For example, in a steering apparatus for an automobile, in order to transmit a rotational force between a steering shaft which does not exist on the same straight line and a pinion shaft which constitutes a steering gear, an intermediate shaft is disposed between the steering shaft and the pinion shaft. And the intermediate shaft and the steering shaft and the pinion shaft are connected via a cross shaft universal joint called a cardan joint, respectively.

  The cross-shaft universal joint is configured by connecting a pair of yokes via a cross shaft to enable torque transmission. Specifically, the cruciform universal joint forms both yokes in a state in which a pair of yokes each formed in a substantially U-shape are opposed to each other with a phase shift of 90 degrees in the circumferential direction. By supporting a rod-like shaft portion constituting a cross shaft rotatably via a radial needle bearing consisting of a bearing cup and a plurality of needles inside a bearing hole provided in each of a pair of arm portions. It is done. Further, in Japanese Patent Application Laid-Open No. 4-87741, the gap between the shaft portion and the needle is set to a negative gap in order to suppress rattling when using the cross shaft universal joint Technology is described.

Japanese Patent Laid-Open No. 4-87741

  By the way, the cross shaft universal joint having the configuration as described above has a portion between the shaft portion and the bearing hole after loosely inserting the shaft portion constituting the cross shaft into the bearing hole provided in the arm portion It is assembled by carrying out the work which incorporates a radial needle bearing in. For this reason, when setting a negative gap between the shaft portion and the needle, there is a possibility that damage such as scratches may be caused on the outer peripheral surface of the needle or the outer peripheral surface of the shaft portion when incorporating the radial needle bearing. is there.

  Also, conventionally, in the case of setting a negative gap between the shaft portion and the needle, a plurality of combinations of a cross shaft and a radial needle bearing, in which the size (absolute value) of the negative gap is appropriate, are used. An operation of selecting (matching) a cross shaft and a radial needle bearing is performed. As a result, the number of assembling steps increases, which causes an increase in cost. Also, since the outer diameter of the shaft directly affects the size of the gap between the shaft and the needle, the outer peripheral surface of the shaft may be ground to satisfy high dimensional accuracy. It is carried out, which again causes the processing cost to increase.

  SUMMARY OF THE INVENTION In view of the above-described circumstances, the present invention is an invention of a cross shaft universal joint in which a negative gap is set between a shaft portion and a needle so as to realize a structure obtained at low cost.

The radial needle bearing according to the present invention rotatably supports a shaft portion constituting a cross shaft inside a bearing hole formed in an arm portion constituting a yoke, and includes a bearing cup and a plurality of needles. Is equipped.
The bearing cup has a cylindrical shape with a bottom, and is fixedly fitted inside the bearing hole.
The plurality of needles are rotatably disposed between an inner peripheral surface of the bearing cup and an outer peripheral surface of the shaft portion.
In the radial needle bearing according to the present invention, at least one needle of the plurality of needles is hollow at the tip end side of the shaft portion and has the bottom portion at the base end side of the shaft portion. It is configured in the shape of

  In the present invention, the inside of the bearing cup can be filled with grease.

  In the present invention, the open end of the at least one needle may be provided with a bent portion which is bent radially inward and whose outer surface is a convex surface.

  In the present invention, the outer diameter dimension of the at least one needle can be made smaller as it goes from the distal end side to the proximal end side of the shaft portion.

In the present invention, all of the plurality of needles can be configured in a hollow shape having a bottom on the tip end side of the shaft and having an opening on the base end side of the shaft.
Alternatively, the plurality of needles may include totally solid needles.

The cross shaft universal joint according to the present invention comprises a pair of yokes having two arm portions provided with bearing holes respectively, a cross shaft having four shaft portions, and the above-mentioned each of the bearing holes inside And 4 radial needle bearings rotatably supporting the shaft portions respectively.
In the cross shaft universal joint of the present invention, at least one radial needle bearing among the four radial needle bearings is the radial needle bearing of the present invention.

In the cruciform universal joint according to the present invention, the shaft portion rotatably supported by the at least one radial needle bearing is a small diameter shaft portion on the tip side around which the plurality of needles are disposed, and a base A stepped shaft can be formed by connecting a large diameter shaft portion on the end side, the small diameter shaft portion, and the large diameter shaft portion by a stepped portion.
Alternatively, the shaft portion rotatably supported by the at least one radial needle bearing may be a tapered shaft whose outer diameter decreases from the distal end side toward the proximal end side.

  According to the radial needle bearing and the cross shaft universal joint of the present invention having the configuration as described above, the cross shaft universal joint having a negative gap set between the shaft portion and the needle can be obtained at low cost.

FIG. 1 is a cross-sectional view showing a steering apparatus for an automobile provided with a cross shaft universal joint according to a first example of the embodiment. FIG. 2 is an enlarged view of a portion A of FIG. FIG. 3 is a cross-sectional view taken along line B-B of FIG. FIG. 4 is a cross-sectional view taken along the line C-C of FIG. FIG. 5 is an enlarged top view of FIG. FIG. 6 is an exploded perspective view of a universal joint according to a first example of the embodiment. FIG. 7 is a view corresponding to FIG. 5 showing a state in which a load in the radial direction is applied from the shaft portion in the first example of the embodiment. FIG. 8 is a view corresponding to FIG. 5 and showing a second example of the embodiment. FIG. 9 is a view corresponding to FIG. 5 and showing a third example of the embodiment. FIG. 10 is a view corresponding to FIG. 5 and showing a fourth example of the embodiment.

First Example of Embodiment
A first example of the embodiment will be described using FIGS. 1 to 7. The illustrated vehicle steering apparatus 1 includes a steering wheel 2, a steering shaft 3, a steering column 4, a pair of universal joints 5 a and 5 b, an intermediate shaft 6, and an electric assist device 7.

  The steering wheel 2 is attached to a rear end portion of a steering shaft 3 rotatably supported inside the steering column 4. The front end portion of the steering shaft 3 is connected to the input shaft of the steering gear unit via a pair of universal joints 5 a, 5 b and an intermediate shaft 6. Therefore, by rotating the steering wheel 2, the input shaft can be rotated. The rotation of the input shaft is converted into linear motion of a rack (not shown) to push and pull the pair of tie rods. Thereby, a steering angle according to the operation amount of the steering wheel 2 is given to the steered wheels. Further, in the illustrated example, since the electric assist device 7 is provided, the force required to operate the steering wheel 2 can be reduced by applying the assist torque from a power source such as an electric motor.

  Although the pair of universal joints 5a and 5b incorporated in the steering apparatus 1 for an automobile as described above are both of the cross-shaft type that is the object of the present invention, these one pair of universal joints 5a and 5b are The basic configuration is the same except that axes to be connected are different. For this reason, in this example, detailed explanation will be made only for the universal joint 5a.

  The universal joint 5a is generally referred to as a cardan joint and enables transmission of rotational force between a pair of shafts that do not exist on the same straight line. And yokes 8a and 8b, a cross shaft 9, and four radial needle bearings 10a to 10d.

  Of the pair of yokes 8a and 8b, the entire yoke 8a is substantially U-shaped, and the base 11a and one axial end edge of the base 11a (left end edge in FIGS. 1 and 2) And two arm portions 12a and 12b extended from the above.

  The base portion 11a is formed in a broken cylindrical shape with one discontinuous portion in the circumferential direction, and an attachment hole 13a penetrating in the axial direction is provided inside thereof. And the end of the output shaft 14 which comprises the electrically-driven assist apparatus 7 is inserted in this attachment hole 13a. Further, in the base portion 11a, a pair of side plate portions 15a and 15b disposed substantially in parallel with each other is provided in portions positioned on both sides of the discontinuous portion in the circumferential direction. The bolt 17a inserted through the through hole 16a formed in one of the side plate portions 15a is a female screw formed on the inner peripheral surface of the through hole 16b formed in the other side plate portion 15b or the through hole 16b. Is screwed into a female screw formed on a nut fixed inside. As a result, the diameter of the base portion 11a is reduced, and the outer peripheral surface of the end of the output shaft 14 is strongly suppressed by the inner peripheral surface of the mounting hole 13a. Further, a part of the connecting shaft 19 provided across the end of the output shaft 14 and the end of the torsion bar 18 is disposed between the pair of side plate portions 15a and 15b, and the yoke 8a and the output are provided. The relative rotation with the shaft 14 is prevented.

  The arm portions 12a and 12b are provided so as to extend in the axial direction from two positions on the opposite side in the radial direction at one end in the axial direction of the base portion 11a, and each has a substantially flat plate shape. Are facing each other. In addition, bearing holes 20a and 20b, which are circular through holes, are provided at the tip of the arm portions 12a and 12b, and penetrate the arm portions 12a and 12b in the thickness direction. The pair of bearing holes 20a and 20b are provided coaxially with each other.

  The other yoke 8b constituting the universal joint 5a basically has the same configuration as the above-described one yoke 8a, and includes a base portion 11b and two arm portions 12c and 12d.

  The base portion 11b is formed in a cylindrical shape with one discontinuous portion in the circumferential direction, and an attachment hole 13b penetrating in the axial direction is provided inside thereof. The end of the inner shaft 21 constituting the intermediate shaft 6 is inserted into the mounting hole 13 b. Further, in the base portion 11b, a pair of side plate portions 15c, 15d disposed substantially in parallel with each other is provided in portions positioned on both sides of the discontinuous portion in the circumferential direction. The bolt 17b inserted through the through hole formed in one of the side plate portions 15c is inserted into the internal thread of the through hole 16c formed in the other side plate portion 15d or the through hole 16c. It is screwed into a female screw formed on a nut fixed inside. As a result, the diameter of the base portion 11 b is reduced, and the outer peripheral surface of the end portion of the inner shaft 21 is strongly held by the inner peripheral surface of the mounting hole 13 b.

  The arm portions 12c and 12d are provided in such a manner as to extend in the axial direction from two positions on the other side in the axial direction of the base portion 11b on the opposite side in the radial direction. They are facing each other. In addition, bearing holes 20c and 20d, which are circular through holes, are provided at the tip of the arm portions 12c and 12d so as to penetrate the arm portions 12c and 12d in the thickness direction. The pair of bearing holes 20c and 20d are also provided coaxially with each other.

  The cross shaft 9 is formed in a cross shape as a whole, and includes a body 22 and four shaft portions 23 a to 23 d that protrude in four directions from the outer peripheral surface of the body 22. The four shaft portions 23 a to 23 d are arranged at equal intervals around the trunk portion 22 with phases shifted by 90 degrees. In addition, the four shaft portions 23a to 23d are configured in a cylindrical shape in which the outer diameter dimension does not change over the entire length.

  The axial tip end surfaces of the shaft portions 23a to 23d are flat surfaces, and the bottomed insertion holes 24 are formed in the state of opening at the central portions of the shaft portions 23a to 23d. Then, a substantially cylindrical pin 25 made of an elastic material is inserted into the insertion hole 24 in a state where the tip end of each pin 25 protrudes in the axial direction more than the tip end face in the axial direction of the shaft portions 23a to 23d (press fit) )doing. Such a pin 25 is held between the bearing cup 26 and the shaft portions 23a to 23d described later, and the distance between the inner surface of the bottom plate portion 29 of the bearing cup 26 and the axial front end surface of the shaft portions 23a to 23d is excessively reduced. To prevent that.

  The tip portions of the shaft portions 23a to 23d having the above-described configuration are rotatably supported inside the bearing holes 20a to 20d using radial needle bearings 10a to 10d.

  Each of the radial needle bearings 10 a to 10 d includes a bottomed cylindrical bearing cup 26 and a plurality of needles 27. Among these, the bearing cup 26 is formed by bending a metal plate by plastic working such as deep drawing, and has a cylindrical fitting cylindrical portion 28, a disk-like bottom plate 29, and an inward ridge 30. And.

  The fitting cylindrical portion 28 has an inner peripheral surface functioning as a raceway surface formed in a cylindrical surface shape. The bottom plate portion 29 closes one axial side of the fitting cylindrical portion 28 (the outer surface side of the arm portions 12a to 12d in the assembled state in the bearing holes 20a to 20d), and the bent portion 31 of the outer diameter side portion And a circular arc portion 32 at the central portion. The bending portion 31 is bent such that the inner surface facing the end surface of the needle 27 is a convex surface. On the other hand, the arc portion 32 is curved such that the inner surface facing the tip end surfaces of the shaft portions 23a to 23d is concave (one side in the axial direction is a convex surface). Then, in the assembled state of the universal joint 5a, the tip end portion of the pin 25 inserted in the shaft portions 23a to 23d is elastically brought into contact with the concave surface which is the inner surface of the arc portion 32. The radius of curvature of the inner surface of the arc portion 32 is sufficiently larger than the radius of curvature of the tip of the pin 25. Further, the inward flange portion 30 is bent radially inward from the other axial side of the fitting cylindrical portion 28 (the inner surface side of the arm portions 12a to 12d in the assembled state in the bearing holes 20a to 20d) It is provided and is curved in the direction in which the surface facing the needle 27 is concave.

  The needle 27 is formed, for example, by subjecting a metal plate such as a stainless steel plate or the like to plastic working such as deep drawing, and between the inner peripheral surface of the fitting cylindrical portion 28 and the outer peripheral surface of the shaft portions 23a to 23d It is arranged to be free to roll. Particularly in this example, all the needles 27 constituting the radial needle bearings 10a to 10d have the bottom 33 at one axial side located on the tip end side (the bottom plate 29 side of the bearing cup 26) of the shaft 23a to 23d. And, it is configured in a hollow shape having an opening 34 on the other axial side located on the proximal end side (the opening side of the bearing cup 26) of the shaft portions 23a to 23d. For this reason, the rigidity of the needle 27 in the diametrical direction of the needle 27 is lower at the other axial direction side where the opening 34 is provided than at the axial direction one side where the bottom portion 33 is provided. Thus, the needle 27 is configured to be elastically deformable in the diametrical direction at least on the other side in the axial direction close to the opening 34. The rolling surface 35 of the needle 27 is a cylindrical surface whose outer diameter does not change over the entire length in the free state of the needle 27. However, in the elastically deformed state of the needle 27, the sectional shape is an elliptical shape whose minor axis is the radial direction. It becomes. Further, the difference between the minor axis and the major axis increases toward the other side in the axial direction.

  In the illustrated example, the thickness (plate thickness) of the needle 27 is the same in the rolling surface 35 portion and the bottom portion 33 which are entirely formed in a cylindrical shape, but the rolling surface 35 portion and the bottom portion 33 And may be different from each other. Further, the thickness of the rolling surface 35 portion is not made the same over the entire length, for example, it is gradually reduced as it goes away from the bottom portion 33 or only in the vicinity of the opening 34 is reduced. You may make it different. In other words, the inner diameter of the needle 27 may be varied in the axial direction.

  The bottom 33 of the needle 27 is a convex curved surface so that the outer surface facing the bottom plate 29 of the bearing cup 26 is a convex.

  Grease 37 is filled inside the bearing cup 26 as shown in FIG. In particular, in the present embodiment, since the needle 27 is formed in a hollow shape, the grease 37 is also filled and held in the internal space 36 of the needle 27.

  In this example, the radial needle bearings 10a to 10d as described above are incorporated in the state where the shaft portions 23a to 23d are loosely inserted inside the bearing holes 20a to 20d. That is, with respect to the yoke 8a, in a state in which the shaft portions 23a and 23b are loosely inserted into the pair of bearing holes 20a and 20b coaxially present, the radial needle bearing 10a from the outer surface side of the arm portions 12a and 12b. , 10b. Similarly, with respect to the yoke 8b, with the shaft portions 23c and 23d loosely inserted into the pair of coaxially arranged bearing holes 20c and 20d, respectively, the radial needle from the outer surface side of the arm portions 12c and 12d Incorporate the bearings 10c and 10d.

In this example having the above configuration, the cross-shaft universal joint 5a in which a negative gap is set between the shaft portions 23a to 23d and the needle 27 can be obtained at low cost.
That is, in this example, since the needle 27 constituting the radial needle bearings 10a to 10d is hollow, the elastic deformation of the needle 27 can be easily adjusted by adjusting the rigidity of the needle 27 in the diameter direction. it can. Therefore, it is possible to set a negative gap between the shaft portions 23a to 23d and the needle 27 while allowing variation in the outer diameter size of the shaft portions 23a to 23d and the inner diameter size of the radial needle bearings 10a to 10d. (You can set the margin). Therefore, the dimensional accuracy required for the outer peripheral surfaces of the shaft portions 23a to 23d can be lowered. For this reason, it becomes possible to omit the matching operation conventionally performed, or to omit cutting and grinding performed on the outer peripheral surfaces of the shaft portions 23a to 23d. That is, the cross shaft 9 including the shaft portions 23a to 23d can be used with the accuracy of the forming process. As a result, in this example, the universal joint 5a in which the negative gap is set between the shaft portions 23a to 23d and the needle 27 can be obtained at low cost.

  Further, since the grease 37 can be filled in the internal space 36 of the needle 27, the needle 27 itself can be provided with the holding performance of the grease 37 and with the supply performance of the grease 37 through the opening 34. be able to.

  Further, the needle 27 has a bottom 33 at one side in the axial direction and an opening 34 at the other side in the axial direction, so that the rigidity of the needle 27 in the diametrical direction can be made more Also, since the axial direction other side portion is lowered, the elastic deformation amount when the load in the radial direction is applied from the shaft portions 23a to 23d is the axial other side portion closer to the trunk portion 22 than the axial direction one side portion It becomes large. For this reason, as shown in FIG. 7, it is possible to generate a gap 38 having a hook-like shape in cross section between the rolling surface 35 of the needle 27 and the outer peripheral surface of the shaft portion 23 b (23 a, 23 c, 23 d). Therefore, the grease 37 (see FIG. 5) discharged from the internal space 36 based on the elastic deformation of the needle 27 can be supplied to the gap 38. Therefore, the grease 37 can be effectively prevented from leaking out of the bearing cup 26. Further, due to the wedge effect, the grease 37 can be efficiently supplied between the rolling surface 35 of the needle 27 and the outer peripheral surface of the shaft portions 23a to 23d, and the rotational resistance of the shaft portions 23a to 23d can be reduced. It will be possible.

  Furthermore, when the radial needle bearings 10a to 10d are assembled inside the bearing holes 20a to 20d, the shaft portions 23a to 23d are inserted (press-fit) from the other side in the axial direction of the needle 27 with low rigidity in the diametrical direction. can do. Therefore, when inserting the tip end of the shaft portion 23a-23d inside the radial needle bearing 10a-10d, the other end in the axial direction of the needle 27 may be elastically deformed largely by the tip portion of the shaft portion 23a-23d. it can. Therefore, the contact state between the needle 27 and the shaft portions 23a to 23d can be alleviated, and surface damage such as galling and dents can be prevented from occurring on the outer peripheral surfaces of the rolling surface 35 and the shaft portions 23a to 23d. .

  Furthermore, the tip end surfaces of the shaft portions 23a to 23d are not brought into direct sliding contact with the inner surface of the bottom plate portion 29 constituting the bearing cup 26, and the tip end portions of the pins 25 provided on the tip portions of the shaft portions 23a to 23d are slid. Since the shaft portions 23 a to 23 d are brought into contact with each other, the sliding contact torque when the shaft portions 23 a to 23 d rotate relative to the bearing cup 26 can be suppressed low. Moreover, the radius of curvature of the inner surface of the arc portion 32 constituting the bottom plate portion 29 is made sufficiently larger than the radius of curvature of the tip portion of the pin 25, so the central axes of the shaft portions 23a to 23d and the radial needle bearings 10a to 10d Even when the center axis of 10 d is deviated, the sliding contact torque when the shaft portions 23 a to 23 d rotate relative to the bearing cup 26 can be suppressed low.

Second Example of Embodiment
A second example of the embodiment will be described with reference to FIG. In this example, a bent portion 39 is provided at the opening side end (the other end in the axial direction) of the needle 27a so as to bend radially inward and to have a convex outer surface.

In this example having the above configuration, when inserting (press-fitting) the shaft 23b (23a, 23c, 23d) inside the radial needle bearing 10b (10a, 10c, 10d), the shaft 23b (23a, 23a, 23d) It is possible to effectively prevent the tip end outer peripheral edge portion 23c, 23d) from being caught on the open end of the needle 27a. Therefore, the inserting operation of the shaft portion 23b (23a, 23c, 23d) can be performed more efficiently. Furthermore, by providing the bent portion 39 at the open end of the needle 27a, the opening of the needle 27a is recessed, so that the retention performance of the grease 37 (see FIG. 5) can be improved.
Other configurations and operational effects are the same as the first example of the embodiment.

Third Example of Embodiment
A third example of the embodiment will be described with reference to FIG. In this example, the shaft portion 23b (23a, 23c, 23d) inserted inside the radial needle bearing 10b (10a, 10c, 10d) is a stepped shaft. Specifically, the shaft portion 23b (23a, 23c, 23d), the small diameter shaft portion 40 on the tip end side where the needle 27 is disposed around, the large diameter shaft portion 41 on the base end side, and these small diameter shaft portions 40 And the large diameter shaft portion 41 and the step portion 42. The stepped portion 42 is located on the proximal end side of the shaft portion 23 b (23 a, 23 c, 23 d) with respect to the opening side end (the other end in the axial direction) of the needle 27.

In the present example having the above-described configuration, since the step portion 42 is provided on the outer peripheral surface of the shaft portion 23b (23a, 23c, 23d), as shown in FIG. The grease 37 (see FIG. 5) can be efficiently supplied to the gap 38 in the form of a cross-section, which is formed when a load is applied. Further, since the grease 37 supplied into the gap 38 can be stopped by the step portion 42, the grease 37 can be easily held in the gap 38. Further, by bringing the end portion on the opening side of the needle 27 into contact with the step portion 42, it is possible to suppress the axial movement (run) of the needle 27 and to suppress the skew of the needle 27.
Other configurations and operational effects are the same as the first example of the embodiment.

Fourth Example of Embodiment
A fourth example of the embodiment will be described with reference to FIG. In this example, the outer diameter of the needle 27b is located on the proximal end side of the shaft portion 23b (23a, 23c, 23d) from an axial one side located on the distal end side of the shaft portion 23b (23a, 23c, 23d) The smaller one is used toward the other side in the axial direction. That is, in the free state of the needle 27b, the rolling surface 35a of the needle 27b is a tapered surface whose outer diameter becomes smaller toward the other side in the axial direction (the body 22 side).

  Furthermore, in the present embodiment, the shaft portion 23b (23a, 23c, 23d) is a tapered shaft whose outer diameter is reduced as it goes from the distal end side to the proximal end side.

In this example having the above configuration, the outer periphery of the shaft portion 23b (23a, 23c, 23d) is in a state before the load in the radial direction is applied to the needle 27b from the shaft portion 23b (23a, 23c, 23d) Between the surface and the rolling surface 35a of the needle 27b, a gap 38a having a wedge shape in cross section can be formed. Therefore, in the present embodiment, the grease 37 (see FIG. 5) can be held in the gap 38a in the form of a wedge in cross section, either before or after the load in the radial direction is applied.
In this example, although the case where both the rolling surface 35a of the needle 27b and the outer peripheral surface of the shaft portion 23b (23a, 23c, 23d) are tapered surfaces has been described, the rolling surface of the needle and the outer periphery of the shaft portion One of the surfaces may be a tapered surface, and the other may be a cylindrical surface.
Other configurations and operational effects are the same as the first example of the embodiment.

In the practice of the present invention, for example, when the amount of elastic deformation of the needles becomes excessive, solid needles are mixed without making all the needles constituting the radial needle bearing hollow (for example, in the circumferential direction) Alternatively, the amount of elastic deformation of the hollow needle can be suppressed to a predetermined amount or less by alternately arranging them.
Moreover, when implementing this invention, it can also be implemented combining the structure of each example of embodiment mentioned above suitably.

1 Steering device for automobile 2 Steering wheel 3 Steering shaft 4 Steering column 5a, 5b Universal joint 6 Intermediate shaft 7 Electric assist device 8a, 8b Yoke 9 Cross shaft 10a to 10d Radial needle bearing 11a, 11b Base 12a to 12d Arm 13a, 13b mounting hole 14 output shaft 15a to 15d side plate portion 16a, 16b, 16c through hole 17a, 17b bolt 18 torsion bar 19 connecting shaft 20a to 20d bearing hole 21 inner shaft 22 body portion 23a to 23d shaft portion 24 insertion hole 25 pin 26 Bearing cup 27, 27a, 27b Needle 28 Fitting cylinder 29 Bottom plate 30 Inward facing section 31 Bending section 32 Arc section 33 Bottom section 34 Opening 35, 35a Rolling surface 36 Internal space 37 Grease 38, 38a Clearance 39 Break Bend 40 small diameter portion 41 large diameter shaft portion 42 the stepped portion

Claims (9)

A radial needle bearing for rotatably supporting a shaft portion constituting a cross shaft inside a bearing hole formed in an arm portion constituting a yoke, comprising:
A bottomed cylindrical bearing cup internally fitted and fixed to the inside of the bearing hole, and a plurality of needles rotatably disposed between an inner circumferential surface of the bearing cup and an outer circumferential surface of the shaft portion; Equipped with
At least one needle among the plurality of needles is configured in a hollow shape having a bottom on the tip end side of the shaft and an opening on the base end side of the shaft.
Radial needle bearing.   The radial needle bearing according to claim 1, wherein the inside of the bearing cup is filled with grease.   The open side end of the at least one needle is provided with a bent portion which is bent radially inward and is curved so that the outer surface is a convex surface. Radial needle bearings described.   The radial needle bearing according to any one of claims 1 to 3, wherein the outer diameter dimension of the at least one needle decreases as it goes from the distal end side to the proximal end side of the shaft portion.   5. The hollow needle according to any one of claims 1 to 4, wherein all the plurality of needles have a bottom on the distal end side of the shaft and an opening on the proximal side of the shaft. The radial needle bearing described in 1.   The radial needle bearing according to any one of claims 1 to 4, wherein the plurality of needles include a generally solid needle. A pair of yokes having two arm portions provided with bearing holes respectively;
A cross shaft with four shaft parts,
Four radial needle bearings rotatably supporting the shafts at the inside of the bearing holes,
A universal joint having a shaft
A cross shaft universal joint in which at least one of the four radial needle bearings is the radial needle bearing according to any one of claims 1 to 6.   The shaft portion rotatably supported by the at least one radial needle bearing is a small diameter shaft portion on the tip end side where the plurality of needles are disposed, a large diameter shaft portion on the proximal end side, The cross shaft universal joint according to claim 7, which is a stepped shaft in which a small diameter shaft portion and the large diameter shaft portion are connected by a step portion.   The cross shaft type according to claim 7, wherein the shaft portion rotatably supported by the at least one radial needle bearing is a tapered shaft whose outer diameter becomes smaller as it goes from the distal end side to the proximal end side. Universal joint.

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