JP2010159805A - Universal joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a universal joint capable of controlling movement in the radial direction of a trunnion with respect to a cup while suppressing a rise in a rocking torque. <P>SOLUTION: Four trunnions 19 of a cross shaft 15 are respectively coupled to yokes 14 corresponding thereto through bearings 20. Each bearing 20 contains a bottomed cylindrical cup 23 and a plurality of needle-like rollers 24. The hemispherical projection 28 projecting toward the inside of the cup 23 is provided at the center part of a bottom 26 of the cup 23. A holding recess 21 is formed at an end 19b of the trunnion 19. An embedded body 22 having elasticity is embedded in the holding recess 21, and has an axial end surface 22a situated on the almost same plane as an end surface 19a of the trunnion 19. By pressing the projection 28 onto the axial end surface 22a, a part thereof is crushed to be plastically deformed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a universal joint having a pair of yokes and a cross shaft.
The universal joint according to the present invention is used in, for example, a vehicle steering apparatus.

Some universal joints include a pair of yokes and a cross shaft that connects these yokes (see, for example, Patent Documents 1 and 2). The cross shaft has four trunnions having a cylindrical shape, and is pivotably connected to each yoke. Each trunnion is connected to a corresponding yoke through a bearing provided individually.
As the bearing, for example, a needle roller bearing including a bottomed cylindrical cup and a plurality of needle rollers housed in the cup is used. The end of each trunnion is inserted into the cup and is rotatably supported by the cup via a plurality of needle rollers.

JP-A-50-50531 Japanese Utility Model Publication No. 3-62232

Some bearings used in universal joints as described above have a positive gap between the outer peripheral surface of the trunnion and the needle rollers. That is, there are some in which the radial distance between the outer peripheral surface of the trunnion and the cup is larger than the outer diameter of the needle rollers.
However, when the gap between the trunnion and the needle roller is a positive gap, for example, when torque is applied to the universal joint, the cross shaft and the needle roller vibrate, and the trunnion and the needle roller In addition, there is a possibility that abnormal noise is generated due to the collision between the cup and the needle roller.

  Such abnormal noise is considered to be suppressed by, for example, pressing the end face of the trunnion with a cup and restricting the movement of the trunnion relative to the cup in the radial direction, but when the end face of the trunnion is pressed with the cup, The frictional force generated between the trunnion and the cup increases the torque (swinging torque) when the cross shaft is swung with respect to the yoke. In particular, in a universal joint used in a vehicle steering apparatus, when the swing torque increases, the steering feeling is lowered.

  If the radial distance between the outer surface of the trunnion and the cup is made smaller than the outer diameter of the needle roller (with a negative gap), vibration of the cross shaft and needle roller can be suppressed, but negative In the case of the gap, there is a risk that the swinging torque may increase or the swinging torque may vary due to friction between the trunnion and the needle rollers. In addition, the life of the bearing may be shortened due to wear of the trunnion and needle rollers. Furthermore, it is necessary to accurately manage the dimensions of each part such as the trunnion and the cup.

  Accordingly, an object of the present invention is to provide a universal joint capable of restricting the movement of the trunnion relative to the cup in the radial direction while suppressing an increase in swinging torque.

  In order to achieve the above object, the invention according to claim 1 is a universal joint in which a pair of yokes are connected by a cross shaft, and the cross shaft (15) has four trunnions (19) having a cylindrical shape. Each trunnion is connected to a corresponding yoke (14) via a bearing (20) provided individually, and the bearing has a bottomed cylindrical cup into which the end (19b) of the trunnion is inserted. (23) and a plurality of rolling elements (24) interposed between the outer peripheral surface of the trunnion and the inner peripheral surface of the cup, and the center of the bottom of the cup faces the inside of the cup. A projecting portion (28) protruding in the center, a recess (21) is formed in the center of the end surface of the trunnion, and an embedding body (22) having elasticity is embedded in the recess. Body is almost the same as the end face of the trunnion A universal joint (6, 7) having a flat surface (22a, 34a) located on the surface, part of which is crushed and plastically deformed by pressing the convex portion against the flat surface. is there.

In this section, the alphanumeric characters in parentheses represent reference numerals of corresponding components in the embodiments described later. In addition, it is not the meaning which limits a claim by these reference symbols.
According to this invention, by pressing the convex portion provided at the center of the bottom of the cup against the flat surface of the embedded body embedded at the end of the trunnion, a part of the embedded body is crushed and plastically deformed. Can be made. Thereby, the recessed part of the shape which fits a convex part can be formed in the position where the convex part was pressed, and a convex part can enter into this recessed part. Moreover, since the recessed part of the shape which fits a convex part is formed in the position where the convex part was pressed, surface contact can be carried out with uniform contact pressure, without making a convex part piece-contact with an embedded body. Therefore, the movement of the trunnion with respect to the cup in the radial direction can be reliably restricted by the engagement between the convex portion and the embedded body. Further, since the embedded body has elasticity, the backlash of the trunnion can be absorbed by the resistance due to the elasticity of the embedded body. Further, the trunnion swings about its central axis, and the convex portion comes into contact with the embedded body at a position passing through the central axis of the trunnion. The swing torque generated by sliding can be reduced. Thereby, the movement to the radial direction of the trunnion with respect to a cup can be controlled, suppressing the raise of rocking | fluctuation torque.

The invention according to claim 2 is the universal joint according to claim 1, wherein the convex portion is formed in a hemispherical shape. According to this invention, it is possible to prevent the convex portion from coming into contact with the embedded body, and to make the contact pressure between the convex portion and the embedded body uniform over the entire contact portion.
According to a third aspect of the present invention, the concave portion has a flat support surface (33) for supporting the embedded body, and the embedded body is a flat supported surface (22b) supported by the support surface. 35a), the universal joint according to claim 1 or 2. According to this invention, by supporting the supported surface of the embedded body by the support surface provided in the recessed portion, it is possible to reliably act on the embedded body without escaping the load from the protruding portion. Thereby, a part of embedded body can be reliably crushed by a convex part, and can be plastically deformed.

It is a mimetic diagram showing a schematic structure of a steering device for vehicles provided with a universal joint concerning one embodiment of the present invention. It is an illustration top view of a universal joint concerning one embodiment of the present invention. FIG. 3 is a schematic partial sectional view of a universal joint taken along line III-III shown in FIG. 2. It is the longitudinal cross-sectional view of the end part of the trunnion which shows the state by which the embedding body was embed | buried in the holding | maintenance recessed part, and an embedding body. It is a longitudinal cross-sectional view of the end portion of the trunnion and the embedded body showing a state before the embedded body is embedded in the holding recess. It is a longitudinal cross-sectional view of a part of the universal joint showing a state in which the convex portion is pressed against the embedded body. It is a longitudinal cross-sectional view of a part of the universal joint showing a state in which the convex portion is separated from the buried body after the convex portion is pressed against the buried body. It is a graph for demonstrating the rigidity of the universal joint which concerns on one Embodiment of this invention. It is a sectional view of a part of the universal joint according to the reference form.

Embodiments of the present invention will be specifically described below with reference to the drawings.
FIG. 1 is a schematic diagram illustrating a schematic configuration of a vehicle steering apparatus 1 including a universal joint according to an embodiment of the present invention.
Referring to FIG. 1, a vehicle steering apparatus 1 includes a steering wheel 2 as a steering member and a rack and pinion mechanism 3 as a steering mechanism.

  The steering wheel 2 is connected to the rack and pinion mechanism 3 via a steering shaft 4 and an intermediate shaft 5. The steering shaft 4 is connected to the intermediate shaft 5 via a universal joint 6, and the intermediate shaft 5 is connected to the rack and pinion mechanism 3 via a universal joint 7. The rotation of the steering wheel 2 is transmitted to the intermediate shaft 5 via the steering shaft 4 and the universal joint 6. The rotation of the intermediate shaft 5 is transmitted to the rack and pinion mechanism 3 via the universal joint 7. Thereby, the rotation of the steering wheel 2 is transmitted to the rack and pinion mechanism 3.

  The rack and pinion mechanism 3 includes a pinion shaft 8 and a rack shaft 9. The pinion shaft 8 includes a shaft portion 10 connected to the intermediate shaft 5 via the universal joint 7 and a pinion 11 provided at an end portion of the shaft portion 10. A rack 12 is formed on the rack shaft 9. The pinion 11 is meshed with the rack 12. The rotation of the steering wheel 2 is transmitted to the pinion shaft 8 via the steering shaft 4 and the intermediate shaft 5, and is converted into an axial movement of the rack shaft 9 by the rack 12 and the pinion 11. Thereby, the turning of the steered wheel 13 is achieved.

FIG. 2 is a schematic plan view of the universal joint 6 according to one embodiment of the present invention. Below, with reference to FIG. 2, the universal joint 6 which connects the steering shaft 4 and the intermediate shaft 5 is demonstrated. The universal joint 7 that connects the intermediate shaft 5 and the pinion shaft 8 has the same configuration as that of the universal joint 6, and therefore the description thereof is omitted.
The universal joint 6 includes a pair of yokes 14 and a cross shaft 15 that connects these yokes 14. One yoke 14 is connected to the end of the steering shaft 4, and the other yoke 14 is connected to the end of the intermediate shaft 5. The steering shaft 4 and the intermediate shaft 5 are connected via a universal joint 6 so that torque can be transmitted.

The pair of yokes 14 has a bifurcated shape and is combined so as to mesh with each other. Each yoke 14 has a pair of tabs 16 that face each other at a distance. Each tab 16 is formed with a fitting hole 17.
FIG. 3 is a schematic partial sectional view of the universal joint 6 taken along line III-III shown in FIG. Below, with reference to FIG. 3, the structure of the universal joint 6 is demonstrated in detail.

  The cross shaft 15 is made of metal, and has a body portion 18 and four trunnions 19 extending in the cross direction around the body portion 18. Each trunnion 19 has a cylindrical shape, and an end surface 19a (tip surface) of the trunnion 19 is substantially flat. The two trunnions 19 that are opposed to each other with the body portion 18 in between are disposed on the same axis. Further, two trunnions 19 facing each other with the body portion 18 interposed therebetween form a pair.

  Two trunnions 19 forming one pair are connected to a pair of tabs 16 of one yoke 14 via bearings 20 provided individually. The two trunnions 19 forming the other pair are connected to a pair of tabs 16 of the other yoke 14 via bearings 20 provided individually. The cross shaft 15 can swing around a predetermined axis passing through the center of the two trunnions 19 connected to the yoke 14 with respect to one yoke 14, and remains with respect to the other yoke 14. It can swing around a predetermined axis passing through the centers of the two trunnions 19.

  In addition, a holding recess 21 (recess) that is recessed from the center of the end surface 19 a of the trunnion 19 along the central axis of the trunnion 19 is formed at the end 19 b of each trunnion 19. Each holding recess 21 is embedded with an embedded body 22 having elasticity. Each embedded body 22 is restricted from moving in the radial direction with respect to the corresponding trunnion 19, and is connected to the trunnion 19 so as to be integrally rotatable. Therefore, when the trunnion 19 swings around its central axis, the trunnion 19 and the embedded body 22 corresponding to the trunnion 19 swing integrally. Each embedded body 22 is formed in a columnar shape, for example, and one axial end surface 22a (flat surface) of each embedded body 22 is formed flat. Each embedded body 22 is embedded in the corresponding holding recess 21 so that one axial end surface 22a is positioned on the same plane as the corresponding end surface 19a of the trunnion 19.

The bearing 20 is a needle roller bearing, for example, and has a bottomed cylindrical cup 23 and a plurality of needle rollers 24 (rolling elements). The cup 23 is made of, for example, a steel plate, and includes a cylindrical peripheral wall 25, a disc-shaped bottom portion 26, and an annular flange 27.
The bottom portion 26 closes one end of the peripheral wall 25, and a convex portion 28 that protrudes toward the inside of the cup 23 is provided at the center portion thereof. The surface of the convex portion 28 (corresponding to the central portion of the inner surface of the bottom portion 26) is formed in a hemispherical shape having a predetermined radius.

  The flange 27 is provided along the other end of the peripheral wall 25 and extends inward from the other end of the peripheral wall 25. The space inside the flange 27 is an opening of the cup 23. The cup 23 is press-fitted, for example, into the corresponding fitting hole 17 in the peripheral wall 25 with the opening directed toward the inside of the yoke 14 (toward the opposing tab 16). Thereby, the cup 23 is held by the corresponding tab 16. Further, the end 19 b of each trunnion 19 is inserted into the corresponding cup 23. An annular seal 29 is fitted on the base end portion (end portion on the body portion 18 side) of each trunnion 19, and the gap between the inner peripheral surface of the flange 27 and the outer peripheral surface of the trunnion 19 is this. Sealed by a seal 29.

  The plurality of needle rollers 24 are arranged in an annular shape along the outer peripheral surface of the trunnion 19 in a posture parallel to the central axis of the corresponding trunnion 19. Each needle roller 24 is interposed between the outer peripheral surface of the trunnion 19 and the inner peripheral surface of the peripheral wall 25. Each needle roller 24 is held between the outer peripheral portion of the bottom portion 26 and the flange 27. The trunnion 19 is supported by the cup 23 via a plurality of needle rollers 24 so as to be rotatable around its central axis.

  The dimension of each part is set so that the radial distance between the outer peripheral surface of the trunnion 19 and the inner peripheral surface of the peripheral wall 25 is larger than the outer diameter of the needle roller 24. Thus, the gap between the trunnion 19 and the needle roller 24 is a positive gap. By making the gap between the trunnion 19 and the needle roller 24 a positive gap, the life of the bearing 20 can be improved compared to the case of a negative gap. Furthermore, the torque (swinging torque) when the cross shaft 15 is swung with respect to the yoke 14 can be reduced. Thereby, the steering feeling of the steering apparatus 1 for vehicles can be improved.

Next, a method for connecting the pair of yokes 14 and the cross shaft 15 will be described.
As for the connection between the pair of yokes 14 and the cross shaft 15, for example, one yoke 14 and the cross shaft 15 are first connected, and then the other yoke 14 and the cross shaft 15 are connected. Specifically, the two trunnions 19 forming one pair are inserted into the corresponding fitting holes 17 from the inside of the two tabs 16 with respect to the one yoke 14. Then, the two cups 23 in which the plurality of needle rollers 24 are accommodated are fitted into the two fitting holes 17 formed in the one yoke 14 from the outside. The end 19 b of the trunnion 19 is inserted into the cup 23 in the process of fitting the cup 23 into the corresponding fitting hole 17. Thereby, one yoke 14 and the cross shaft 15 are connected via the two bearings 20.

  Further, when the cup 23 is fitted into the fitting hole 17, the convex portion 28 formed in the bottom portion 26 comes into contact with one axial end surface 22 a of the embedded body 22 embedded in the holding concave portion 21, and the convex portion 28 is This is performed until it is pressed against the embedded body 22. The pressing force of the convex portion 28 against the embedded body 22 is the distance between the two cups 23, specifically, the distance W1 from the outer surface of the bottom portion 26 of one cup 23 to the outer surface of the bottom portion 26 of the other cup 23. (Hereinafter referred to as “set width W1”). When the assembled width W1 is reduced, the pressing force of the convex portion 28 against the embedded body 22 is increased, and when the assembled width W1 is increased, the pressing force of the convex portion 28 against the embedded body 22 is decreased.

  Thus, by pressing the convex portion 28 provided on the cup 23 against the embedded body 22 embedded in the end portion 19b of the trunnion 19, the movement of the trunnion 19 relative to the cup 23 in the radial direction can be restricted. it can. Further, by restricting the movement of the trunnion 19 with respect to the cup 23 in the radial direction, even if the gap between the trunnion 19 and the needle roller 24 is a positive gap, the vibration of the cross shaft 15 is suppressed. Can be suppressed. As a result, for example, when torque is applied to the universal joint 6, it is possible to suppress or prevent the trunnion 19 and the needle roller 24 from colliding with each other and generating abnormal noise.

  Further, when the convex portion 28 and the embedded body 22 are brought into contact with each other at a position passing through the central axis of the trunnion 19, when the trunnion 19 corresponding to the cup 23 is relatively rotated, the sliding between the convex portion 28 and the embedded body 22 is performed. The swing torque generated by the movement can be reduced. Further, since the embedded body 22 has elasticity, even if the pressing amount of the convex portion 28 against the embedded body 22 is increased, the embedded body 22 is elastically deformed to contact the convex portion 28 with the embedded body 22. It is possible to suppress or prevent the pressure from increasing significantly. Accordingly, it is possible to suppress or prevent the sliding resistance between the convex portion 28 and the embedded body 22 from being significantly increased and the swinging torque from being significantly increased. Therefore, since the swinging torque can be kept within a predetermined range without accurately managing the assembly width W1, the dimensional accuracy of the assembly width W1 can be relaxed and the assembly of the universal joint 6 can be facilitated. it can.

  Next, the other yoke 14 and the cross shaft 15 are connected. That is, the two trunnions 19 forming the other pair are inserted into the corresponding fitting holes 17 from the inside of the two tabs 16 with respect to the other yoke 14. Then, the two cups 23 in which the plurality of needle rollers 24 are accommodated are fitted into the two fitting holes 17 formed in the other yoke 14 from the outside. The end 19 b of the trunnion 19 is inserted into the cup 23 in the process of fitting the cup 23 into the corresponding fitting hole 17. As a result, the other yoke 14 and the cross shaft 15 are coupled via the two bearings 20. In the fitting of the cup 23 to the fitting hole 17, as in the case of one yoke 14, the convex portion 28 formed on the bottom portion 26 contacts one axial end surface 22 a of the embedded body 22 embedded in the holding concave portion 21. This is performed until the convex portion 28 is pressed against the embedded body 22.

  FIG. 4 is a longitudinal sectional view of the end 19 b of the trunnion 19 and the embedded body 22 showing a state in which the embedded body 22 is embedded in the holding recess 21. FIG. 5 is a longitudinal sectional view of the end 19 b of the trunnion 19 and the embedded body 22 showing a state before the embedded body 22 is embedded in the holding recess 21. Below, with reference to FIG. 4 and FIG. 5, the holding | maintenance recessed part 21 and the embedded body 22 are demonstrated in detail.

  The holding recess 21 is formed in a cylindrical shape coaxial with the trunnion 19, for example. As shown in FIG. 5, the holding recess 21 includes a cylindrical large diameter portion 30, a truncated cone-shaped intermediate portion 31, and a cylindrical small diameter portion 32. The large diameter portion 30, the intermediate portion 31, and the small diameter portion 32 are formed so as to be coaxial with the trunnion 19. The small diameter portion 32, the intermediate portion 31, and the large diameter portion 30 are arranged in this order from the bottom side of the holding recess 21. Is arranged in.

  The large diameter portion 30 has a longer axial length (length along the central axis) than the intermediate portion 31 and the small diameter portion 32. The large diameter portion 30 is connected to the small diameter portion 32 by an intermediate portion 31. The intermediate portion 31 is inclined so that the diameter continuously decreases from the large diameter portion 30 toward the small diameter portion 32. Further, the small diameter portion 32 forms the bottom portion of the holding recess 21. The small diameter portion 32 is provided with a flat bottom surface 33 (support surface) corresponding to the bottom of the holding recess 21. The bottom surface 33 is a surface orthogonal to the central axis L1 of the trunnion 19, and is formed in a circular shape in plan view, for example.

  The embedded body 22 is made of, for example, a synthetic resin or a synthetic rubber and has elasticity. In this embodiment, the embedded body 22 is formed of a synthetic resin exemplified by polyacetal (POM), polyamide (PA), phenol resin (PF), polyether ether ketone (PEEK), and the like. The embedded body 22 is formed in a shape corresponding to the holding recess 21 (or a columnar shape if the holding recess 21 is cylindrical), and has a cylindrical large-diameter fitting portion 34 and a small-diameter fitting that are connected coaxially. A portion 35 is provided. As shown in FIG. 4, the embedded body 22 is embedded in the holding recess 21 so as to be coaxial with the trunnion 19. The embedded body 22 is held in the holding recess 21 by press-fitting the small-diameter fitting portion 35 into the holding recess 21.

  That is, as shown in FIG. 5, the outer diameter D <b> 1 of the small-diameter fitting portion 35 in the free state is larger than the diameter D <b> 2 of the small-diameter portion 32 of the holding recess 21. Further, the axial length of the small diameter fitting portion 35 is longer than the axial length of the small diameter portion 32. As shown in FIG. 4, the distal end portion (the lower end portion in FIG. 4) of the small diameter fitting portion 35 is fitted to the small diameter portion 32. As a result, the tip of the small diameter fitting portion 35 is press-fitted into the small diameter portion 32, and the embedded body 22 is held in the holding recess 21. When the trunnion 19 swings around the central axis L1, the trunnion 19 and the embedded body 22 corresponding to the trunnion 19 swing integrally.

  As shown in FIG. 4, the base end portion (the end portion on the large diameter fitting portion 34 side) of the small diameter fitting portion 35 is located in the intermediate portion 31. An annular space S1 is formed around the base end portion of the small diameter fitting portion 35. Furthermore, the front end surface 35a (the lower end surface in FIGS. 4 and 5; a supported surface) of the small-diameter fitting portion 35 is formed as a flat surface that is circular in plan view. As shown in FIG. 4, the front end surface 35 a of the small diameter fitting portion 35 is supported by surface contact by the bottom surface 33 of the holding recess 21. Accordingly, the embedded body 22 is positioned with respect to the bottom surface 33 of the holding recess 21. The distal end surface 35 a of the small diameter fitting portion 35 corresponds to the other axial end surface 22 b of the embedded body 22.

  On the other hand, the large diameter fitting part 34 is located in the large diameter part 30, as shown in FIG. As shown in FIG. 5, the outer diameter D3 of the large diameter fitting portion 34 is slightly smaller than the diameter D4 of the large diameter portion 30, and the axial length of the large diameter fitting portion 34 is the large diameter portion. The length is approximately the same as the axial length of 30. As shown in FIG. 4, the large-diameter fitting portion 34 is fitted into the large-diameter portion 30 with a gap. Since the outer diameter D3 of the large-diameter fitting portion 34 is smaller than the diameter D4 of the large-diameter portion 30, the large-diameter fitting portion is inserted into the large-diameter portion 30 when the embedded body 22 is inserted into the holding recess 21. 34 can enter smoothly. Further, when the embedded body 22 is inserted into the holding recess 21, it is prevented that the embedded body 22 hits the end surface 19 a of the trunnion 19 and scratches or chips are generated in the embedded body 22.

  Moreover, the front end surface 34a (the upper end surface in FIGS. 4 and 5; a flat surface) of the large-diameter fitting portion 34 is formed as a flat surface that is circular in plan view. As shown in FIG. 4, the distal end surface 34 a of the large-diameter fitting portion 34 is located on substantially the same plane as the end surface 19 a of the trunnion 19 in a state where the embedded body 22 is embedded in the holding recess 21. That is, the axial length of the embedded body 22 is set so that the tip surface 34a of the large-diameter fitting portion 34 is substantially flush with the end surface 19a of the trunnion 19 in a state where the embedded body 22 is embedded in the holding recess 21. Is set. The convex portion 28 provided on the bottom portion 26 of the cup 23 is pressed against the distal end surface 34 a of the large diameter fitting portion 34. The distal end surface 34 a of the large-diameter fitting portion 34 corresponds to one axial end surface 22 a of the embedded body 22.

FIG. 6 is a longitudinal sectional view of a part of the universal joint 6 showing a state in which the convex portion 28 is pressed against the embedded body 22. FIG. 7 is a longitudinal sectional view of a part of the universal joint 6 showing a state where the convex portion 28 is separated from the embedded body 22 after the convex portion 28 is pressed against the embedded body 22. Below, with reference to FIG. 6 and FIG. 7, the pressing state of the convex part 28 with respect to the embedded body 22 is demonstrated.
As described above, the convex portion 28 provided on the bottom portion 26 of the cup 23 is pressed against the embedded body 22. Accordingly, the two trunnions 19 forming a pair arranged on the same axis are sandwiched in the axial direction A1 by the corresponding two cups 23 via the embedded bodies 22 embedded in the respective end portions 19b (FIG. 3). Therefore, the movement of the paired trunnions 19 with respect to the cup 23 in the radial direction R <b> 1 is restricted by the clamping force received from the corresponding two cups 23. Further, since the embedded body 22 has elasticity, when the two trunnions 19 making a pair vibrate in the axial direction A1, the vibration is absorbed by the elasticity of the embedded body 22.

  Further, since the embedded body 22 has elasticity, when the convex portion 28 is pressed against the embedded body 22, the embedded body 22 is compressed in the axial direction A1 by the convex portion 28 and the bottom surface 33 of the holding concave portion 21. The embedded body 22 is elastically deformed. At this time, a part of the embedded body 22 enters the annular space S <b> 1 provided in the holding recess 21. In other words, in this embodiment, the annular space S1 functions as an escape space for allowing a part of the embedded body 22 to escape when the embedded body 22 is compressed. By providing this escape space, the embedded body 22 can be easily bent when the embedded body 22 is compressed.

  Moreover, in this embodiment, the pressing force of the convex part 28 with respect to the embedded body 22 is set so that the edge part of the embedded body 22 is crushed by the convex part 28 and plastically deforms. Therefore, a recessed portion 36 having a shape that fits the protruding portion 28 (in this embodiment, a hemisphere having a radius substantially equal to the surface of the protruding portion 28) is provided at the end of the embedded body 22 at the position where the protruding portion 28 is pressed. It is formed. Therefore, the tip end portion (the lower end portion in FIG. 6) of the convex portion 28 comes into surface contact with the substantially uniform contact pressure without entering the embedded body 22 in a state of entering the concave portion 36.

  By causing the distal end portion of the convex portion 28 to enter the concave portion 36, the distal end portion of the convex portion 28 can function as a hooking portion, and movement of the trunnion 19 relative to the cup 23 in the radial direction R <b> 1 can be restricted. Further, the two trunnions 19 forming a pair are sandwiched in the axial direction A1 by the corresponding two cups 23 and the movement in the axial direction A1 is restricted, so that each trunnion 19 has the axial direction A1 and the diameter. Movement in the direction R1 is restricted. In the universal joint 6 according to the present embodiment, the rattling of the trunnion 19 with respect to the cup 23 is reliably prevented in this way, and the rigidity is increased.

  When the radius of the surface of the convex portion 28 is R (see FIG. 6), the crushed amount P1 of the embedded body 22 (from the axial end surface 22a in the state where the convex portion 28 is separated from the embedded body 22 to the bottom of the concave portion 36) The distance along the axial direction A1 (see FIG. 7) is set to 0.08 × R or more. As will be described later, by setting the crushing amount P1 of the embedded body 22 to be 0.08 × R or more, the movement of the trunnion 19 relative to the cup 23 in the radial direction R1 can be made extremely small. Thereby, the backlash of the trunnion 19 with respect to the cup 23 in the radial direction R <b> 1 can be reduced, and generation of abnormal noise from the universal joint 6 can be reliably suppressed or prevented.

  Further, since the embedded body 22 has elasticity, when the trunnion 19 vibrates in the radial direction R <b> 1 by causing the tip of the convex portion 28 to enter the concave portion 36 and contact with the embedded body 22, this vibration is generated. Can be absorbed by the elasticity of the embedded body 22. That is, in the universal joint 6 according to the present embodiment, the vibration of the trunnion 19 in the axial direction A1 is absorbed by the elasticity of the embedded body 22 as described above. The vibration in the direction A1 can be absorbed. Thereby, generation | occurrence | production of the abnormal noise by the vibration of the trunnion 19 can be suppressed or prevented reliably.

  In addition, since the two trunnions 19 forming a pair are supported by the two cups 23 via the two embedded bodies 22, when the torque acting on the universal joint 6 is small, the needle rollers 24 are not interposed. The power can be transmitted between the cup 23 and the trunnion 19 via the buried body 22. Further, when the torque acting on the universal joint 6 is large, power is transmitted between the cup 23 and the trunnion 19 via the needle rollers 24, but the trunnion is caused by the resistance due to the elastic deformation of the embedded body 22. The speed of the trunnion 19 when the 19 collides with the needle roller 24 can be reduced. Thereby, the impact when the trunnion 19 collides with the needle roller 24 can be weakened, and the sound caused by the collision between the two can be reduced.

  Further, as described above, since the concave portion 36 having a shape that fits the convex portion 28 is formed at the end portion of the embedded body 22 at the position where the convex portion 28 is pressed, the convex portion 28 is formed on the embedded body 22. Surface contact can be achieved with a substantially uniform contact pressure without causing a single contact. That is, for example, when the recessed portion 36 is formed in advance in the embedded body 22 and the convex portion 28 is inserted into the recessed portion 36, the embedded body must be managed unless the dimensions, shape, and position of the convex portion 28 and the recessed portion 36 are accurately controlled. The convex portion 28 comes into contact with 22. However, if the convex portion 28 comes into contact with the embedded body 22, the rattling of the trunnion 19 with respect to the cup 23 may not be sufficiently restricted. Further, since the contact pressure between the convex portion 28 and the embedded body 22 becomes very high, the embedded body 22 is likely to be worn when the convex portion 28 and the embedded body 22 slide. Therefore, as in this embodiment, the recessed portion 36 is formed by crushing the embedded body 22 with the convex portion 28, so that the convex portion 28 can be surely brought into surface contact with the embedded body 22 without causing a single contact. it can. Further, since the concave portion 36 having a shape that fits the convex portion 28 is formed at the position where the convex portion 28 is pressed, precise management such as dimensions is unnecessary. Therefore, the protrusion 28 can be prevented from hitting the embedded body 22 without depending on the accuracy of the protrusion 28 and the embedded body 22.

  FIG. 8 is a graph for explaining the rigidity of the universal joint 6 according to an embodiment of the present invention. The vertical axis of each graph shown in FIG. 8 indicates the magnitude of torque applied to the steering wheel 2 (unit: Nm), and the horizontal axis indicates the rotational displacement amount of the universal joint 6 (one yoke). 14 and the relative rotation amount of the other yoke 14 (unit: minutes). The measured value in each graph is the rotational displacement amount of the universal joint 6 when torque is applied to the steering wheel 2 in a range of about ± 1 Nm.

  The measured values in FIG. 8A, FIG. 8B, and FIG. 8C are obtained when the crushing amount P1 (see FIG. 7) of the embedded body 22 is changed, respectively, and FIG. Is a measured value when the crushed amount P1 of the buried body 22 is 0.7 mm, and FIG. 8B is a measured value when the crushed amount P1 of the buried body 22 is about 0.1 mm. The crushing amount P1 of the embedded body 22 in the measurement value of FIG. 8B is a value obtained by multiplying the radius R (see FIG. 6) of the surface of the convex portion 28 by 0.08. Therefore, the crushing amount P1 of the embedded body 22 in the measured value of FIG. 8A is larger than the value obtained by multiplying the radius R of the convex portion 28 by 0.08. Further, the measured values shown in FIG. 8C are obtained when the embedded body 22 is elastically deformed by pressing the convex portion 28 against the embedded body 22 without plastic deformation. That is, the crushing amount P1 of the embedded body 22 in the measured value of FIG. 8C is zero.

  When the crushed amount P1 of the buried body 22 is 0.7 mm, the absolute value of the rotational displacement amount of the universal joint 6 when the torque is applied to the steering wheel 2 in the range of about ± 1 Nm (the rotational displacement amount to the positive side). The value obtained by adding the absolute value and the absolute value of the amount of rotational displacement to the negative side) was about 2 minutes (see FIG. 8A). The absolute value of the rotational displacement of the universal joint 6 when the torque is applied to the steering wheel 2 in the range of about ± 1 Nm when the crushing amount P1 of the embedded body 22 is about 0.1 mm is about 5 minutes. (See FIG. 8 (b)). The absolute value of the rotational displacement amount of the universal joint 6 when the torque was applied to the steering wheel 2 in the range of about ± 1 Nm when the crushing amount P1 of the embedded body 22 was zero was about 5 minutes ( (Refer FIG.8 (c)).

  Looking at each graph in more detail, two lines L2 each straddle the horizontal axis in the vertical axis direction. Looking at the intersection between each line L2 and the horizontal axis, the rotational displacement amount of the universal joint 6 is not zero and takes a positive or negative value. However, the intersection of each line L2 and the horizontal axis is the rotational displacement amount of the universal joint 6 when the torque acting on the steering wheel 2 is zero, and if the torque acting on the steering wheel 2 is zero, the universal joint 6 The amount of rotational displacement should also be zero. Therefore, when the torque acting on the steering wheel 2 is zero, the fact that the amount of displacement is not zero is determined that there is a backlash in the universal joint 6. Moreover, it is judged that the backlash of the universal joint 6 is large that the space | interval of the two lines L2 on a horizontal axis is wide.

  8A, 8B, and 8C from this point of view, in the measured value of FIG. 8C, the distance between the two lines L2 on the horizontal axis is as follows. It is very big. Therefore, it can be seen that the backlash of the trunnion 19 with respect to the cup 23 cannot be sufficiently regulated simply by pressing the convex portion 28 against the embedded body 22 without plastically deforming the embedded body 22. On the other hand, when the measured values in FIGS. 8A and 8B are viewed, the distance between the two lines L2 on the horizontal axis is very narrow. That is, the embossed body 22 is crushed and plastically deformed by the convex portion 28, and the crushing amount P1 of the embedded body 22 is set to 0.08 × R or more, thereby moving the trunnion 19 relative to the cup 23 in the radial direction R1. Can be very small. Thereby, the backlash of the trunnion 19 in the radial direction R1 with respect to the cup 23 can be reduced, and the rigidity of the universal joint 6 can be increased. Therefore, it is possible to reliably suppress or prevent the generation of abnormal noise from the universal joint 6.

  As described above, in this embodiment, by pressing the convex portion 28 provided at the center portion of the bottom portion 26 of the cup 23 against the axial end surface 22a of the embedded body 22 embedded in the end portion 19b of the trunnion 19. A part of the embedded body 22 can be crushed and plastically deformed. Thereby, the recessed part 36 of the shape which fits the convex part 28 can be formed in the position where the convex part 28 was pressed, and the convex part 28 can be entered in this recessed part 36. FIG. Moreover, since the recessed part 36 of the shape which fits the convex part 28 is formed in the position where the convex part 28 was pressed, the surface contact is made by the uniform contact pressure without causing the convex part 28 to come into contact with the embedded body 22. be able to. Therefore, the movement of the trunnion 19 with respect to the cup 23 in the radial direction R <b> 1 can be reliably restricted by the engagement between the convex portion 28 and the embedded body 22. Further, since the embedded body 22 has elasticity, the backlash of the trunnion 19 can be absorbed by the resistance due to the elasticity of the embedded body 22. Further, the trunnion 19 swings around its central axis L1, and the convex portion 28 comes into contact with the embedded body 22 at a position passing through the central axis L1 of the trunnion 19, so that The swing torque generated by the sliding between the portion 28 and the embedded body 22 can be reduced. Moreover, in this embodiment, since the embedded body 22 is made of synthetic resin, the friction coefficient of the embedded body 22 is smaller than when the embedded body 22 is formed of other materials such as metal. Yes. Therefore, the frictional resistance caused by sliding between the convex portion 28 and the embedded body 22 is reduced, and the swing torque is further reduced. Furthermore, since the embedded body 22 is formed of a synthetic resin, generation of abnormal noise due to sliding between the convex portion 28 and the embedded body 22 is prevented. In this way, an increase in swing torque is suppressed, and movement of the trunnion 19 with respect to the cup 23 in the radial direction R1 is restricted.

  Further, in this embodiment, since the embedded body 22 is supported by the bottom surface 33 of the holding recess 21, the load from the convex portion 28 can be reliably applied to the embedded body 22. That is, as shown in the reference form of FIG. 9, when a holding recess 38 is formed in the end 37 a of the trunnion 37 by a drill, and a cylindrical embedded body 39 is embedded in the holding recess 38, the embedded body 39 is It is held in the holding recess 38 while being supported by line contact. Therefore, when the convex portion 40 is pressed against the buried body 39 in such a supported state, a part of the buried body 39 enters the inverted conical space on the bottom side of the holding concave portion 38 (enclosed by circles in FIG. 9). The load applied to the embedded body 39 from the convex portion 40 escapes. Therefore, the embedded body 39 cannot be reliably crushed by the convex portion 40. Therefore, as in this embodiment, a flat bottom surface 33 that is orthogonal to the direction of the load applied from the convex portion 28 to the embedded body 22 is provided, and the embedded body 22 is supported by surface contact by the bottom surface 33, thereby The load from the portion 28 can be reliably applied to the embedded body 22. Thereby, the embedded body 22 can be reliably crushed and plastically deformed by the convex portion 28.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the contents of the above-described embodiments, and various modifications can be made within the scope of the claims. For example, in the above-described embodiment, the case where the present invention is applied to the universal joints 6 and 7 provided in the vehicle steering apparatus 1 has been described, but the universal joint provided in an apparatus other than the vehicle steering apparatus 1 may be used. The present invention may be applied. In the above-described embodiment, the case where the bearing 20 is a needle roller bearing has been described. However, other radial rolling bearings using rolling elements other than the needle rollers 24 may be used as the bearing 20. Furthermore, although the case where the surface of the convex portion 28 is formed in a hemispherical shape has been described in the above-described embodiment, the surface of the convex portion 28 may be formed in other shapes such as a conical shape or a truncated cone shape. Good. In addition, various design changes can be made within the scope of matters described in the claims.

6, 7 ... Universal joint, 14 ... Yoke, 15 ... Cross shaft, 19 ... Trunnion, 19b ... End (end of trunnion), 20 ... Bearing, 21 ... Holding recess (recess), 22 ... buried body, 22a ... axial end surface (flat surface), 22b ... axial end surface (supported surface), 23 ... cup, 24 ... needle Rollers (rolling elements), 28 ... convex portions, 33 ... bottom surface (support surface), 34a ... tip surface (flat surface), 35a ... tip surface (supported surface)

Claims (3)

A universal joint in which a pair of yokes are connected by a cross shaft,
The cross shaft has four trunnions forming a cylindrical shape,
Each trunnion is connected to a corresponding yoke through individually provided bearings,
The bearing has a bottomed cylindrical cup into which the end of the trunnion is inserted, and a plurality of rolling elements interposed between the outer peripheral surface of the trunnion and the inner peripheral surface of the cup,
A convex portion that protrudes toward the inside of the cup is provided at the center of the bottom of the cup,
A concave portion is formed in the central portion of the end surface of the trunnion,
An embedded body having elasticity is embedded in the concave portion, and the embedded body has a flat surface located on substantially the same plane as the end surface of the trunnion, and the convex portion is pressed against the flat surface. A universal joint, part of which is crushed and plastically deformed.   The universal joint according to claim 1, wherein the convex portion is formed in a hemispherical shape. The concave portion has a flat support surface that supports the embedded body,
The universal joint according to claim 1, wherein the embedded body has a flat supported surface supported by the support surface.

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