JP6521065B2 - Universal Joint Yoke - Google Patents

Description

  The present invention is a cruciform type that connects various ends of a pair of rotating shafts that do not exist on the same straight line and that enables transmission of a rotational force between the rotating shafts, which constitute various mechanical devices. The present invention relates to the improvement of the yoke that constitutes the universal joint of the present invention.

  For example, a non-linearly arranged universal joint of cross-shaft type is incorporated at the connection between the end of the drive shaft constituting the drive system of an automobile and another rotational shaft, and these drive shaft and rotational shaft are arranged non-linearly. It is practiced to freely transmit the rotational force between the two. In addition, a universal joint of a cross shaft type is incorporated in a connecting portion between a steering shaft and an intermediate shaft, a connecting portion between the intermediate shaft and a pinion shaft of a steering gear unit, etc. which constitutes a steering apparatus for an automobile. It has been practiced to freely transmit the rotational force between the shafts (rotational axes) arranged linearly.

  For example, a steering apparatus of a car is configured as shown in FIG. The movement of the steering wheel 101 operated by the driver is transmitted to the input shaft 106 of the steering gear unit 105 via the steering shaft 102, the universal joint 1s, the intermediate shaft 104, and another universal joint 1t. Then, the left and right tie rods 107, 107 are pushed and pulled by the rack and pinion mechanism built in the steering gear unit 105, and an appropriate steering angle according to the operation amount of the steering wheel 101 is applied to the left and right steered wheels. It is configured to give.

As universal joints 1s and 1t to be incorporated in such a steering apparatus, generally, a cross axis universal joint called a cardan joint as illustrated in FIG. 8 is widely used. The universal joints 1s and 1t respectively include a pair of yokes 2a and 2b, and a cross shaft 3 that pivotally connects tip portions of the pair of yokes 2a and 2b. In the universal joint 1s, the base of one yoke 2a is coupled so as to be able to transmit torque to the rear end of the male shaft 110 which is a solid shaft constituting the intermediate shaft 104, and the base of the other yoke 2b is steering At the front end of the shaft 102, torque transmission is coupled and fixed. In the universal joint 1t, the base of one yoke 2a is coupled so as to be able to transmit torque to the front end of the female shaft 111 which is a hollow shaft constituting the intermediate shaft 104, and the base of the other yoke 2b is an input To the rear end portion of the shaft 106, torque transmission is coupled and fixed. The intermediate shaft 104 is configured by combining a male shaft 110 and a female shaft 111 so as to be able to transmit torque and allow relative displacement in the axial direction.
Thus, the structure of the universal joint of the cross-shaft type incorporated in the connecting part is conventionally widely known, as described in many publications.

FIGS. 9 to 10 show an example of a conventionally well-known universal joint of cross-shaft type which is applicable as the universal joints 1s and 1t of the steering apparatus described above.
The universal joint 1 comprises a pair of yokes 2a and 2b coupled by way of a single cross shaft 3 so as to be capable of transmitting torque.

  The yokes 2a and 2b are integrated integrally by applying stamping such as punching or bending to a metal plate having sufficient rigidity such as steel plate, or forging on a metal material such as steel. A base 4a (4b) and a pair of connecting arms 5a provided so as to extend axially to one side from two positions on the radial opposite side of the base 4a (4b), And 5a (5b, 5b). A coupling hole 6a (6b) is provided at the radial center of the base 4a (4b) so as to axially penetrate the center. Also, circular holes 7a and 7a (7b and 7b) are provided coaxially at the tip end portions of the coupling arm portions 5a and 5a (5b and 5b), respectively.

  In addition, the cross shaft 3 is fixed to the outer peripheral surface of the joint base provided at the central portion so that four shafts 8 are provided such that central axes of adjacent shafts 8 are orthogonal to each other. Become. The respective shaft portions 8, 8 are rotatably supported inside the respective circular holes 7a, 7b via cup shell type radial needle bearings 9, 9, respectively. For example, as shown in FIG. 8, a plurality of cup shell type radial needle bearings 9, 9 are provided in a bottomed cylindrical bearing cup 21 fitted and fixed in the respective circular holes 7a, 7b. The shaft portion 8 of the cross shaft 3 is rotatably supported via the needles 22.

  When the ends of a pair of rotary shafts 10a and 10b are connected in a freely transmittable manner by the universal joint 1 having the above-described configuration, the outer peripheral surface of the rotary shafts 10a and 10b is a yoke 2a, The inner peripheral surfaces of the coupling holes 6a and 6b of 2b are fitted (for example, cylindrical surface fitting or serration fitting in a state where an interference is given). Furthermore, if necessary, a part of the yokes 2a, 2a and a part of the rotating shafts 10a, 10b are crimped or welded and joined. As a result, the yokes 2a and 2b and the end portions of the rotating shafts 10a and 10b are coupled and fixed so as to transmit torque. In this state, the universal joint 1 can transmit torque between the rotating shafts 10a and 10b even when the rotating shafts 10a and 10b are inclined to each other.

  In the case of the universal joint 1 as described above, when torque is transmitted between the rotary shafts 10a and 10b, the tips of the pair of coupling arms 5a and 5a (5b and 5b) constituting the yokes 2a and 2b. The couple in the rotational direction acts on the part. As a result, the base end portions of the coupling arms 5a, 5a (5b, 5b) {particularly, of the inner side surfaces of the coupling arms 5a, 5a (5b, 5b) are continuous with one axial end face of the base 4a (4b) A large stress is applied to the concave surface portions 11, 11} which are the parts due to the moment of the couple force. Therefore, in order to ensure the durability of the yokes 2a and 2b against such stress, conventionally, the thickness of the yokes 2a and 2b is increased, or a high strength material is used as the material of the yokes 2a and 2b. Things are being done. However, when these means are adopted, there is a problem that it is difficult to suppress the weight increase and cost increase of the yokes 2a and 2b.

  On the other hand, as shown by a chain line in FIG. 9, the radius of curvature of the cross-sectional shape of the base end portions (concave surface portions 11 and 11) of the coupling arms 5a and 5a is increased without changing the thickness of the yoke 2a. For example, while preventing or suppressing weight increase and cost increase, stress applied to the base end portions (concave surface portions 11, 11) of the joint arms 5a, 5a is alleviated to improve the durability of the yoke 2a. Can. However, as illustrated, if the radius of curvature of the cross-sectional shape of the proximal end (concave surface portions 11 and 11) of the coupling arms 5a and 5a is simply increased, the proximal end of the coupling arms 5a and 5a is accompanied accordingly. The portions project inward (in the directions indicated by arrows α and α) with respect to the opposing direction (vertical direction in FIG. 9) of the coupling arms 5a and 5a. As a result, when the joint angle of the universal joint 1 (the angle of inclination of the central axes of the yokes 2a and 2b) is increased, the base ends of the connecting arms 5a and 5a are the connecting arms of the mating yoke 2b. There is a possibility that the joint angle can not be made sufficiently large by interfering with the tip of 5b. Also, in order to avoid such interference, if the length of the connecting arms 5a, 5a is increased, the length of the arm due to the couple also increases, so it acts on the proximal end of the connecting arms 5a, 5a. The problem arises that the stress becomes larger.

  Further, Patent Document 1 describes a structure in which a convex portion such as a reinforcing rib is provided at the central portion in the width direction of the inner side surface of the base end portion of a pair of connecting arms constituting a yoke. By adopting such a structure, the durability of the yoke can be improved while suppressing the increase in weight and cost as compared with the case where the thickness of the entire yoke is increased. However, even in the case of adopting such a structure, when the joint angle of the universal joint is increased in a state where the universal joint is assembled, the convex provided on the inner surface of the base end of the joint arm The part may interfere with the tip of the joint arm of the mating yoke, making it impossible to make the joint angle sufficiently large.

Japanese Examined Patent Fair 7-111210

  SUMMARY OF THE INVENTION In view of the above-described circumstances, the present invention can improve durability while preventing or suppressing weight increase and cost increase, as well as constituting a universal joint, with regard to a yoke constituting a universal joint of cross-shaft type. It is invented in order to realize the structure which is easy to secure the joint angle of this universal joint in a state.

The universal joint yoke of the present invention comprises a base and a pair of coupling arms.
The base of these is fixed to the end of the rotating shaft.
Further, the two coupling arms are provided in a state of extending to one side in the axial direction from two positions on the radially opposite side of the base.
Moreover, the part continuous with the axial direction one end surface of the said base among the inner surface of both the said connection arm parts is a concave curve part, respectively.
In particular, in the case of the universal joint yoke according to the present invention , an axial one- half which is at least one axial side of the biconcave curved surface portion is the biconcave curved surface portion among the inner side surfaces of the two coupling arms. On the other hand, it is located outside with respect to the opposing direction of both said coupling arm parts rather than the part adjacent to axial direction one side ,
The base end portions of the both coupling arms are provided with curved plate portions having an inner side surface as the concave surface portion and an outer surface as a convex surface portion curved in the same direction as the concave surface portion, and At least the axial half of the biconvex curved surface portion is in the opposing direction of the two coupling arms relative to the portion adjacent to one axial direction of the biconvex curved surface in the outer surface of the two coupling arms. Located outside
The thickness of a portion of the two coupling arms which is a portion of the two curved plates adjacent to one side in the axial direction of the two curved plates is constant.
The two connecting arms are curved in the width direction so that the center in the width direction is separated from the ends in the width direction from the base end to the tip .

  In the case of practicing the universal joint yoke of the present invention, for example, the radial central portion of the base is provided with a coupling hole axially penetrating the central portion, and the coupling hole is the rotary shaft. A press-in hole for press-fitting the end of the shaft, and a non-press-in hole having a diameter larger than the press-in hole axially adjacent to the press-in hole and in which the end of the rotary shaft is not press-fitted It may have a part.

  Further, the universal joint yoke of the present invention can be used in a steering device.

In the case of the universal joint yoke of the present invention configured as described above, it is possible to improve the durability while preventing or suppressing weight increase and cost increase, and in the state where the universal joint is configured, this universal joint It is easy to secure the joint angle of
That is, in the case of the yoke for a universal joint of the present invention , an axial direction which is at least one axial side of a concave surface portion which is a continuous portion with the axial direction end face of the base among the inner side surfaces of the pair of coupling arms One half of the inner side surface of the coupling arm is positioned outward with respect to the direction in which the coupling arms oppose each other than a portion adjacent to one axial direction of the concave curved surface. Therefore, the radius of curvature of the concave surface portion can be increased by that amount. As a result, the stress applied to the concave surface portion can be relaxed to improve the durability.
Further, in the case of the present invention, the above-mentioned configuration is adopted without increasing the thickness of the universal joint yoke or changing the material of the universal joint yoke to a high strength material. Can improve the durability. Therefore, the durability of the yoke can be improved while preventing or suppressing the increase in weight and cost.
Furthermore, in the case of the present invention, as a configuration for improving the durability of the yoke, at least one axial half of the concave surface portion is one side of the inner surface of the coupling arm in the axial direction of the concave surface portion. The structure which is located outside regarding the opposing direction rather than the part which adjoins to is employ | adopted. For this reason, even if the joint angle of the universal joint is increased in a state in which the universal joint according to the present invention is provided with the universal joint yoke, the tip of the joint arm of the mating yoke has a concave curved surface (joint arm Interference with the proximal end of the Therefore, the joint angle can be easily secured.
Further, in the case of the present invention, at the base end portions of both coupling arms, a curved plate having an inner side surface as a concave curved surface and an outer side surface as a convex curved surface curved in the same direction as the concave curved surface is respectively While being provided, at least one axial half of the biconvex curved surface portion is closer to the axial direction of the biconvex curved surface than the portion adjacent to the one axial direction of the biconvex curved surface. Since it is located on the outside with respect to the opposing direction, the thickness of the curved plate can be increased, and the durability of the yoke can be easily ensured.
Further, in the case of the present invention, both coupling arms are curved in the width direction so that the center in the width direction is separated from the ends in the width direction from the base end to the tip end. Thus, the strength of the bonding arm can be improved.

The partial side view of the universal joint provided with the yoke of one Embodiment of this invention. (A)-(C) is a figure which takes out only the yoke of this embodiment, and shows three examples of the shape seen from the downward direction of FIG. The figure which looked at the yoke of FIG. 2 (A) from III direction. The figure which shows the 1st modification of this embodiment. The figure which shows the 2nd modification of this embodiment. The figure which shows the 3rd modification of this embodiment. FIG. 10 is a partial cutaway side view showing an example of a steering device conventionally known. The partially cut side view of the intermediate shaft which connected the conventional cross-shaft universal joint provided with the vertical insertion type yoke with the both ends. The partial side view of the universal joint of conventional structure. The disassembled perspective view of the universal joint of conventional structure.

A universal joint provided with a yoke according to an embodiment of the present invention will be described with reference to FIGS.
The yoke 2c of the present embodiment is integrally formed as a whole by subjecting a metal plate having sufficient rigidity such as a steel plate or the like to a stamping process such as punching or bending, and the base 4c and the base 4c. A pair of coupling arms 5c provided in a state of extending to one side (right side in FIG. 1) in the axial direction (left and right direction in FIG. 1) from two positions on the opposite radial side (upper and lower sides in FIG. 1) , 5c. A coupling hole 6c is provided at a radial center of the base 4c so as to axially penetrate the center. In addition, circular holes 7c and 7c are provided coaxially with each other in the tip end portion (the axial direction one end side) portion of the coupling arms 5c and 5c, respectively.

  Further, in the case of the present embodiment, the base end portions which are the other axial end portions (left end portions in FIG. 1) of the coupling arms 5c, 5c are axially one side from two positions on the radial opposite side of the base 4c. The curved plate portions 12, 12 are bent in a substantially 1⁄4 arc shape toward the end. On the other hand, the remaining portions of the coupling arms 5c, 5c, that is, the tip and middle portions of the coupling arms 5c, 5c are parallel plate portions 13, 13 parallel to each other. The circular holes 7 c, 7 c are provided coaxially with each other in the tip end portion of the parallel plate portions 13, 13.

  Further, in the case of the present embodiment, each portion of the yoke 2c (including a portion adjacent to one side in the axial direction of the curved plate portions 12 and 12 to the curved plate portions 12 and 12 in the coupling arms 5c and 5c) The thickness (plate thickness) t is substantially constant throughout, except for the leading end edges of the coupling arms 5c, 5c. At the same time, in the case of the present embodiment, the curved plate portions 12, 12 and the axial half of the curved plate portions 12, 12 (the right half portion in FIG. The bonding arms 5c and 5c are formed to expand outward (in the directions indicated by arrows β and β) with respect to the opposing direction (vertical direction in FIG. 1) of each other. That is, in the case of the present embodiment, the concave curved surface portions 14 and 14 having an arc-shaped cross section which is the inner side surface of the curved plate portions 12 and 12 (of the inner side surfaces of the coupling arms 5c and 5c, the axial direction of the base 4c 1) of the inner side surfaces of the parallel plate portions 13 and 13 from the portion adjacent to one side in the axial direction of the concave surface portions 14 and 14) Also, they are located outside in the opposite direction. In other words, a partial circular arc in which the concave surface portions 14 and 14 are smoothly continued to the axial end face of the base 4 c and the inner side surfaces of the parallel plates 13 and 13 (the axial direction of the base 4 c at the other end edge in the axial direction A partial arc in contact with one end surface and in contact with the inner side surface of the parallel plate portions 13 and 13 at one axial end is positioned outside (outward with respect to the radial direction of this partial arc) in the opposite direction. At the same time, the axial direction half of the convex curved surface portion 15, 15 which is the outer surface of the curved plate portion 12, 12 (right half in FIG. 1) is taken as the outer surface of the parallel plate portion 13, 13. Among the above, a portion adjacent to one side in the axial direction of the convex curved surface portions 15 and 15 is positioned outside in the opposing direction. In other words, a partial circular arc in which the convex curved surface portion 15, 15 is smoothly continued to the other end surface of the base 4c in the axial direction and the outer surface of the parallel plate portion 13, 13 (in the axial direction of the base 4c at the other end edge in the axial direction A partial arc in contact with the other end face and in contact with the outer surface of the parallel plate portion 13 at one axial end is positioned outside (outward with respect to the radial direction of this partial arc) in the opposite direction.

  Further, in the case of the present embodiment, by adopting the configuration as described above with respect to the curved plate portions 12, 12, as shown by a chain line in FIG. 1, the base 4c and the parallel plate portions 13, 13 are smoothed. The radius of curvature (the radius of curvature r of the concave surface portions 14 and the radius of curvature R of the convex surface portions 15) of the sectional shape of the curved plate portions 12 and 12 is larger than in the case of adopting the configuration in which doing. In the case of the present embodiment, the cross sectional shapes of the concave curved surface portions 14 and 14 and the cross sectional shapes of the convex curved surface portions 15 and 15 have a single circular arc shape, and the circular arc angle is larger than 90 °. There is. However, when carrying out the present invention, these cross-sectional shapes can also be made into a compound curve shape in which a plurality of curves or straight lines having different radii of curvature are made to be smoothly continuous.

  Further, in the case of the present embodiment, with regard to the coupling arms 5c, 5c, a coupling arm as shown in FIG. 2A, the shape of the boundary portion 16 between the curved plate portions 12, 12 and the parallel plate portions 13, 13 is shown. It has a straight line parallel to the width direction (vertical direction in FIG. 2) of the portion 5c. However, in the case of practicing the present invention, for example, as shown in FIG. 2 (B), the central portion in the width direction of the connecting arm 5c protrudes to the distal end side of the connecting arm 5c. Alternatively, as shown in FIG. 2C, the central portion in the width direction of the connecting arm 5c may be an arc extending out to the base end of the connecting arm 5c. it can.

When the universal joint 1a is configured by combining the yoke 2c of the present embodiment as described above and another yoke 2b via one cross shaft 3 (for details, see FIG. 4), this cross shaft One of the four shaft parts 8 and 8 constituting 3 is provided inside the respective circular holes 7c and 7b provided in the yokes 2c and 2b, and can be freely rotated via the cup shell type radial needle bearings 9 and 9, respectively. To support. When the base 4c of the yoke 2c is coupled with the end of the rotary shaft 10a so as to freely transmit the torque, the outer peripheral surface of the rotary shaft 10a is the inner periphery of the coupling hole 6c provided in the base 4c. The surface is fitted (for example, cylindrical surface fitting or serration fitting in a state where the interference is given). Furthermore, if necessary, a part of the yoke 2c and a part of the rotary shaft 10a are welded and joined by caulking or welding metal 17.
In addition, in FIG. 3, the case where the coupling hole 6c is a serration hole is shown.

In the case of the yoke 2c of the present embodiment configured as described above, it is possible to improve the durability while preventing or suppressing weight increase and cost increase, and in the state where the universal joint 1a is configured, this universal joint It is easy to secure the joint angle of 1a.
That is, in the case of the yoke 2c of the present embodiment, the curved plate portions 12, 12 constituting the base end portions of the coupling arms 5c, 5c are different from the parallel plate portions 13, 13 with respect to the parallel plate portions 13, 13. The connecting arms 5c, 5c are formed to bulge outward with respect to the opposing direction of each other. Thereby, the radius of curvature (r, r) of the cross-sectional shape of the curved plate portions 12 and 12 (concave surface portions 14 and 14 and convex surface portions 15 and 15) as compared with the case where the configuration shown by the chain line in FIG. R) is enlarged. Therefore, the stress applied to the curved plate portions 12 and 12 (concave surface portions 14 and 14 and the convex surface portions 15 and 15) is relieved, and the base end portions of the coupling arms 5c and 5c, and in turn, the entire yoke 2c. Can improve the durability of the
Further, in the case of the present embodiment, the connecting arms 5c and 5c do not increase the thickness (plate thickness) of the metal plate constituting the yoke 2c or change the metal plate to a high strength one. The durability can be improved by adopting the configuration as described above. For this reason, durability can be improved while preventing or suppressing weight increase and cost increase.
Furthermore, in the case of the present embodiment, the positions of the curved plate portions 12 and 12 (concave curved surface portions 14 and 14 and convex curved surface portions 15 and 15) are compared to the positions of the conventional structure as shown by dashed lines in FIG. And are retracted outward in the opposite direction. For this reason, even if the joint angle of the universal joint 1a is increased, the tip end portions of the connecting arms 5b of the other yokes 2b are less likely to interfere with the curved plate portions 12, 12. Therefore, the joint angle can be easily secured.

  Further, in the case of the present embodiment, the axial direction half of the concave surface portion 14, which is the inner side surface of the curved plate portion 12, 12 is a concave surface portion among the inner side surfaces of the parallel plate portions 13, 13 In addition to adopting a configuration in which the portions 14 and 14 adjacent to one side in the axial direction are positioned outside with respect to the opposing direction, convex curved portions 15 and 15 that are outer surfaces of the curved plate portions 12 and 12 Of the outer surface of the parallel plates 13 and 13 is positioned more outward in the opposite direction than the portion adjacent to one side in the axial direction of the convexly curved portions 15 and 15 . For this reason, compared with the case where only the former structure is adopted, the thickness of the curved plate portions 12, 12 can be increased, and the durability of the yoke 2c can be easily secured by that much.

Further, in the case of the present embodiment, the thickness of a continuous portion of the coupling arms 5c, 5c that is adjacent to one side in the axial direction of the curved plate portions 12, 12 from the curved plate portions 12, 12 Is a substantially constant thickness t. For this reason, in the case of the present embodiment, with respect to the facing direction of the convex curved surface parts 15 with respect to the part adjacent to one side in the axial direction of the convex curved surface parts 15 among the outer surface of the parallel plate parts 13. The outward protrusion width W _out is to the outside in the opposing direction of the concave surface portions 14, 14 with respect to the portion adjacent to one axial direction of the concave surface portions 14, 14 among the inner side surfaces of the parallel plate portions 13, 13 Is approximately equal to the recessed width W _in of (W _out W W _in ).

However, as the protrusion width W _out of the convex curved surface portions 15 becomes larger, it may be easier to interfere with other members present in the periphery.
Therefore, in the case of practicing the present invention, the radius of curvature R of the convex curved surface portion 15 is made smaller than in the case of the above-described embodiment {a radius of curvature R of the convex curved surface portion 15 is a concave curved surface portion The protrusion width W _out of the convex curved surface portion 15 is obtained by setting (R <r + t) to be smaller than the sum (r + t) of the curvature radius r of 14 and 14 and the thickness t of the curved plate portion 12. It is also possible to make it smaller (W _out <W _in ) than the concave width W _in of the concave surface portions 14, 14.
However, in any case, in order to prevent interference between the curved plate portions 12 and 12 and other members present around the curved plate portions 12 and 12, the outward protrusion width W _{out in} the opposing direction of the convex curved surface portions 15 and 15, The concave width W _in to the outer side in the opposing direction of the concave curved surface portions 14 is smaller than the thickness t of the curved plate portions 12 (W _out , W _in <t).

  FIG. 4 shows a universal joint 1b in which a yoke 2d according to a first modification of the embodiment is used. As in this modification, the curved plate portions 12, 12 may have only the concave surface portions 14, 14 and may not have the convex surface portions 15, 15. That is, the outer side surfaces of the coupling arms 5c, 5c are flat from the parallel plates 13, 13 to the curved plates 12, 12 without providing the convexly curved portions 15, 15 on the curved plates 12, 12. , Up to the base 4c smoothly.

FIG. 5 shows a universal joint 1c in which a yoke 2e according to a second modification of the present embodiment is used. The yoke 2c of this modification is different in that a recess and a protrusion are formed on the front and back of the base 4c. A coupling hole 60c is provided at a radial center of the base 4c so as to axially penetrate the center. And the recessed part 60e larger diameter than the joint hole 60c is formed in the axial direction (right-left direction of FIG. 5) one side (right side of FIG. 5) of the base 4c. The recess 60e is composed of a cylindrical wall portion 60a and a bottom portion 60b formed to be continuous with the wall portion 60a. Further, on the other side in the axial direction of the base 4c (left side in FIG. 5), an annular convex portion 60d surrounding the coupling hole 60c is formed to project from the base 4c. The convex portion 60d has a partial conical shape which becomes smaller toward the axial distal end side. Then, the outer peripheral surface of the end portion of the rotation shaft 10a is press-fitted into the inner peripheral surface of the connecting hole 60c provided in the base 4c. Further, a part of the base 4c including the convex part 60d and a part of the rotary shaft 10a are welded and joined by the weld metal 17.
That is, the other side in the axial direction of the connecting hole 60c is a press-in hole for press-fitting the end of the rotating shaft 10a, and the one axial side portion axially adjacent to the press-in hole is the rotating shaft 10a. The non-press-in hole is not pressed into the end of the

Therefore, in the case of the yoke 2e of the second modification, the surface layer portion of the coupling hole 60c which will be the press-in hole by the recess 60a of the coupling hole 60c and the inner circumferential surface of the wall 60a which is the non-press-in hole of the coupling hole 60c. And a continuous portion 60f of the side face in the axial direction of the base 4c are located apart from each other.
Here, the surface layer portion of the coupling hole 60c is a portion where a large hoop stress (tensile stress in the circumferential direction) is generated as the end portion of the rotating shaft 10a is press-fit into the coupling hole 60c, and the continuous portion 60f is At the time of torque transmission in the assembled state of the cross shaft universal joint, a stress concentration due to torsion occurs. However, in the second modification, since the surface layer portion of the coupling hole 60c and the continuous portion 60f exist at positions separated from each other, a portion where a large hoop stress occurs due to the press-in and a stress concentration due to torsion occur. The maximum value of the stress generated in the base 4c can be kept low compared to the structure in which the portions overlap with each other. As a result, the design for securing the strength of the base 4c can be easily performed.

FIG. 6 shows a universal joint 1d in which a yoke 2f according to a third modification of the present embodiment is used. In the above embodiment, the curved plate portions 12, 12 and the parallel plate portions 13, 13 of the coupling arms 5c, 5c are formed in a straight line along the width direction of the coupling arms 5c, 5c as shown in FIG. However, in the case of the third modification, the curved plate portions 12, 12 and the parallel plate portions 13, 13 of the coupling arms 5c, 5c are in the width direction of the coupling arms 5c, 5c (left and right direction in FIG. 6). In the above, the central portion is curved, for example, by an arc shape convex toward the outer diameter side so that the central portions are separated more than the end portions. By thus bending the curved plate portions 12 and 12 and the parallel plate portions 13 and 13, the strength of the coupling arms 5c and 5c can be improved.
Also in the case of the third modified example, in the cross section in the width direction, the cross sectional shapes of the coupling arms 5c, 5c are the same as those in the above embodiment, and the parallel plate portions 13 are parallel to each other in the axial direction. Further, the circular holes 7 c and 7 c are also provided coaxially with each other at the tip end portions of the parallel plate portions 13 and 13.

The yoke for a universal joint according to the present invention is not only a product produced by subjecting a metal plate such as a steel plate or the like to a press process such as punching or bending (so-called press yoke) but also forging a metal material such as steel It can also be applied to what is manufactured (so-called forged yoke).
The yoke for a universal joint according to the present invention is a universal joint provided with slits for elastically expanding and contracting the inner diameter of the base (the inner diameter of the coupling hole) at one circumferential direction of the base. The present invention can also be applied to a yoke for a universal joint in which a base is integrally fixed (integrally formed) to an end of a rotating shaft.
In the case of practicing the present invention, the whole of the pair of concave surface portions (convex surface portions) is the concave surface portion (convex surface portion) of the inner side surface (outer surface) of the pair of coupling arms. It can also be located outside with respect to the opposing direction of joint arm parts rather than the part adjacent to the axial direction one side of.
Further, the universal joint yoke of the present invention can be applied to at least one of the universal joints 1s and 1t of the steering apparatus shown in FIG. 7, and may be applied to all the yokes of the universal joints 1s and 1t. .

  This application is based on Japanese Patent Application No. 2015-116590 filed on June 9, 2015, Japanese Patent Application No. 2016-018457 filed on February 3, 2016, Japanese Patent Application No. 2016-027465 filed on February 17, 2016 The contents of which are incorporated herein by reference.

1, 1a, 1b, 1c, 1d Universal Joints 2a, 2b, 2c, 2d, 2e, 2f Yoke 3 Cross Shaft 4a, 4b, 4c Base 5a, 5b, 5c Coupling Arm 6a, 6b, 6c, 60c Coupling Hole 7a , 7b, 7c Round hole 8 axis 9 radial needle bearing 10a, 10b Rotary axis 11 concave surface 12 curved plate 13 parallel plate 14 concave surface 15 convex surface 16 boundary 17 weld metal

Claims (3)

A base fixed to an end of the rotation shaft;
And a pair of coupling arms provided so as to extend axially to one side from two radially opposite sides of the base,
Of the inner side surfaces of the both coupling arms, portions continuous with one axial end face of the base are concave curved portions, respectively.
A universal joint yoke,
An axial one- half which is at least one axial side of the biconcave curved surface portion is more than a portion adjacent to the one axial direction of the biconcave curved surface portion of the inner side surfaces of the two coupling arms. Located on the outside with respect to the facing direction of the parts ,
The base end portions of the both coupling arms are provided with curved plate portions having an inner side surface as the concave surface portion and an outer surface as a convex surface portion curved in the same direction as the concave surface portion, and At least the axial half of the biconvex curved surface portion is in the opposing direction of the two coupling arms relative to the portion adjacent to one axial direction of the biconvex curved surface in the outer surface of the two coupling arms. Located outside
The thickness of a portion of the two coupling arms which is a portion of the two curved plates adjacent to one side in the axial direction of the two curved plates is constant.
The two connecting arms are curved in the width direction so that the center in the width direction is separated from the ends in the width direction from the base end to the tip end. ,
Universal joint yoke. The radially central portion of the base is provided with a coupling hole axially penetrating the central portion,
The coupling hole has a press-in hole for press-fitting the end of the rotary shaft, and a diameter larger than the press-in hole axially adjacent to the press-in hole, the end of the rotary shaft The yoke for a universal joint according to claim 1, further comprising: a non-press-fit hole not pressed into. Used in the steering device, universal joint yoke according to claim 1 or 2.

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