JP2020112202A - Yoke for universal joint - Google Patents

Abstract

To provide a yoke for a universal joint which hardly needs aftertreatment work such as burr removal and has a body part with low deflection stiffness.SOLUTION: The yoke for a universal joint comprises: a base part having a body part into which a portion to be held of a shaft is inserted, and a pair of leg parts held by screw fastening while coming close to each other; and an arm part extending from the base part. A holding portion of the base part comprises a female serration, and the portion to be held comprises a male serration meshing with the female serration. The body part has a thick portion and a thin portion having a smaller thickness than that of the thick portion.SELECTED DRAWING: Figure 3

Description

The present disclosure relates to a universal joint yoke.

The universal joint connects two shafts that intersect each other. In detail, the universal joint includes a pair of yokes fixed to the respective shafts, and a cross shaft connecting the pair of yokes. The yoke has, for example, a U-shaped main body portion into which the shaft is inserted on the inner peripheral side, and a pair of leg portions extending from both ends of the main body portion. Male serrations are provided on the outer peripheral surface of the shaft, and female serrations that mesh with the male serrations of the shaft are provided on the inner peripheral surface of the main body. When the shaft is inserted into the main body and the male serration and the female serration are engaged with each other, the pair of legs are tightened by the screw members to bring the pair of legs closer to each other, and the yoke is fixed to the shaft.

Here, when the flexural rigidity of the main body is high, the amount of elastic deformation of the main body due to the tightening of the screw member is small. As a result, the contact area between the male serration of the shaft and the female serration of the yoke is reduced, and the female serration teeth may be damaged. In Patent Document 1, the flexural rigidity of the main body is lowered by providing an opening in the main body.

JP, 2017-137895, A

When the opening is provided by cutting, burrs are generated around the opening, so that it takes time and labor to remove the burr.

The present disclosure has been made in view of the above problems, and an object of the present disclosure is to provide a universal joint yoke in which post-processing work such as removal of burrs is unlikely to occur, and the flexural rigidity of the main body is low. ..

In order to achieve the above object, in a yoke for universal joint according to one aspect, a held portion of a shaft is inserted on an inner peripheral side, a main body portion that covers a portion of the held portion in a circumferential direction, and the main body portion. A pair of legs arranged at both ends in the circumferential direction and held in a state of being close to each other by screw fastening, the main body portion is provided with female serrations, and the held portion is provided with the female serrations. A male serration that meshes with the main body portion is provided, and the main body portion has a thick portion and a thickness smaller than that of the thick portion, and the axial center of the main body portion is sandwiched between the slits between the pair of leg portions. And a thin portion arranged on the opposite side.

When the flexural rigidity of the main body is high, the amount of elastic deformation of the main body due to screw fastening is small. In this case, the contact area between the male serration of the shaft and the female serration of the universal joint yoke becomes small, and the teeth of the female serration may be damaged. Here, the main body part in the present disclosure includes a thick part and a thin part having a smaller thickness than the thick part. The thin portion reduces the flexural rigidity of the main body portion and increases the elastic deformation amount of the main body portion due to screw fastening. Further, since the thin portion can be formed by, for example, forging, the work for removing burrs that occurs when forming the opening by punching is reduced. Therefore, according to the present disclosure, there is provided a universal joint yoke in which post-processing work such as removal of burrs is unlikely to occur and the flexural rigidity of the main body is low.

As a desirable aspect, each of the pair of leg portions is provided with a screw hole through which a screw member penetrates and is fastened, and the thin-walled portion is one of the pair of leg portions on the outer peripheral surface of the main body portion. Is provided on the first circumferential line connecting the first screw hole provided in the first leg portion and the second screw hole provided in the other second leg portion in the circumferential direction.

When the first leg portion and the second leg portion approach each other by screw fastening, the largest bending stress is applied to the portion on the first circumferential line connecting the first screw hole and the second screw hole in the circumferential direction. .. Therefore, by providing the thin-walled portion on the first circumferential line, the flexural rigidity of the main body portion further decreases, the elastic deformation amount of the main body portion due to the screw fastening becomes larger, and the damage of the teeth of the female serration is further prevented. be able to.

As a desirable mode, the thin portion is provided so as to be connected from a first peripheral edge portion of the first screw hole to a second peripheral edge portion of the second screw hole.

Since the thin portion is provided so as to extend from the first peripheral portion of the first screw hole to the second peripheral portion of the second screw hole, the length of the thin portion along the first circumferential line should be set longer. You can

As a desirable mode, the main body portion or the leg portion includes a toothless portion that is a smooth surface on an inner peripheral surface on one side with respect to a plane that is parallel to the axial center and that passes through the slit, and the thin-walled portion is on the flat surface. In contrast, it is provided on the outer peripheral surface on the side where the toothless portion is provided.

Since the toothless portion does not mesh with the male serration of the shaft, the portion having the toothless portion has a lower tightening force for tightening the shaft with the yoke than the female serration portion. Therefore, by disposing the toothless portion and the thin portion on one side with respect to the plane passing through the slit, the flexural rigidity of the main body portion is further reduced, and the teeth of the female serration are further prevented from being damaged.

According to the present disclosure, there is provided a universal joint yoke in which post-processing work such as removal of burrs is unlikely to occur and the flexural rigidity of the main body is low.

FIG. 1 is a schematic diagram of the steering device according to the first embodiment. FIG. 2 is a cross-sectional view of the universal joint yoke and the shaft of the first embodiment. FIG. 3 is a perspective view showing the universal joint yoke of the first embodiment. FIG. 4 is a side view of FIG. FIG. 5 is a sectional view showing a state before the shaft is inserted into the universal joint yoke. FIG. 6 is a cross-sectional view showing a state of an initial stage in which the shaft is inserted into the universal joint yoke. FIG. 7 is a cross-sectional view showing a state in which the shaft has been inserted into the universal joint yoke. FIG. 8 is a perspective view showing a universal joint yoke according to the second embodiment. FIG. 9 is a side view of FIG. FIG. 10 is a cross-sectional view showing a yoke for a universal joint according to the second embodiment. FIG. 11 is a perspective view showing a universal joint yoke according to the third embodiment. FIG. 12 is a side view of FIG. FIG. 13 is a sectional view taken along the line AA of FIG. FIG. 14 is a perspective view showing a universal joint yoke according to the fourth embodiment. FIG. 15 is a side view of FIG. 16 is a sectional view taken along line BB of FIG.

Modes (embodiments) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the embodiments below. Further, the components described below include those that can be easily conceived by those skilled in the art and those that are substantially the same. Furthermore, the components described below can be combined as appropriate.

[First Embodiment]
First, the first embodiment will be described.

FIG. 1 is a schematic diagram of a steering device 10 according to the first embodiment. As shown in FIG. 1, the steering device 10 includes a steering wheel 11, a steering shaft 12, a steering force assist mechanism 13, a first universal joint 14, a shaft 15, and a second universal joint 16. It is joined to the pinion shaft 17.

The held portion 41 provided at one end of the shaft 15 is connected to the first universal joint 14. The held portion 41 provided at the other end of the shaft 15 is connected to the second universal joint 16. The shaft 15 connects the first universal joint 14 and the second universal joint 16. One end of the pinion shaft 17 is connected to the second universal joint 16. The other end of the pinion shaft 17 is connected to the steering gear 18. The first universal joint 14 and the second universal joint 16 are, for example, cardan joints. The rotation of the steering shaft 12 is transmitted to the pinion shaft 17 via the shaft 15. The shaft 15 rotates along with the steering shaft 12.

The steering gear 18 includes a pinion 18a and a rack 18b. The pinion 18 a is connected to the pinion shaft 17. The rack 18b meshes with the pinion 18a. The steering gear 18 converts the rotational movement transmitted to the pinion 18a into a linear movement by the rack 18b. The rack 18b is connected to the tie rod 19. The angle of the wheels changes as the rack 18b moves.

FIG. 2 is a sectional view of the universal joint yoke 20 and the shaft 15 of the first embodiment. FIG. 3 is a perspective view showing the universal joint yoke 20 of the first embodiment. FIG. 4 is a side view of FIG. Note that FIG. 2 shows a state in which one end of the shaft 15 is held by the universal joint yoke 20 of the first universal joint 14. Further, in the following, the first direction D1 is a direction along the axial direction of the main body 23. The second direction D2 is a direction orthogonal to (intersecting) the first direction D1 and is the vertical direction of the paper surface of FIGS. 2 to 4. The third direction D3 is a direction orthogonal (crossing) to both the first direction D1 and the second direction D2. Hereinafter, the "universal joint yoke" is also simply referred to as "yoke".

The yoke 20 has a base portion 21 and an arm portion. The yoke 20 is formed by forging, for example.

The base 21 has a main body 23 and a pair of legs. The main body portion 23 extends in the left-right direction (first direction D1) on the paper surface of FIGS. The main body 23 has a U-shape (inverted U-shape) whose lower portion is opened by the slit 26 when viewed from the first direction D1. A holding portion 40 that holds the held portion 41 of the shaft 15 is provided on the inner peripheral side of the main body portion 23. The holding portion 40 is provided with female serrations 401. The end of the shaft 15 is set on the held portion 41, and the held portion 41 is provided with a male serration 410. The female serrations 401 of the holding portion 40 and the male serrations 410 of the held portion 41 mesh with each other.

In a cross section orthogonal to the first direction D1, the pair of legs extend downward (second direction) from both ends of the main body 23 and are arranged to face each other while being separated from each other in the left-right direction (third direction D3). Specifically, the pair of legs includes a first leg 24 extending downward from the left first end 232 shown in FIG. 3 and a second leg 25 extending downward from the right second end 233 shown in FIG. And. A slit 26 extending in the front-rear direction (first direction D1) is provided between the first leg portion 24 and the second leg portion 25.

The first leg portion 24 and the second leg portion 25 are provided with a first screw hole 241 and a second screw hole 242. A first screw hole 241 is provided in the first leg portion 24. The first screw hole 241 can be inserted, for example, by penetrating a male screw portion of a bolt (screw member). A second screw hole 242 is provided in the second leg 25. On the inner peripheral side of the second screw hole 242, for example, a female screw portion with which a male screw portion of a bolt (screw member) meshes is provided.

The arm portion 22 extends forward from the base portion 21 (first direction D1). The arm part 22 has a first arm part 221 located on the lower side and a second arm part 222 located on the upper side. The arm portion 22 has a first arm portion 221 and a second arm portion 222 that branch vertically from the base portion 21 and extend. A first bearing holding hole 221a is provided in the first arm portion 221. The second arm portion 222 is provided with a second bearing holding hole 222a. The first bearing holding hole 221a and the second bearing holding hole 222a are arranged to face each other while being separated in the vertical direction (second direction D2).

As described above, the male screw portion of the bolt (screw member) is inserted (inserted) from the first screw hole 241, the male screw portion is engaged with the female screw portion of the second screw hole 242, and the bolt is rotated, whereby the first screw hole is formed. The first leg 24 and the second leg 25 approach each other in the third direction D3 (left-right direction). Thereby, the held portion 41 of the shaft 15 can be held by the holding portion 40 of the yoke 20. As shown in FIG. 2, with the shaft 15 held by the yoke, the axis of the main body 23 and the shaft 15 is Ax1, and the axes of the first bearing holding hole 221a and the second bearing holding hole 222a are Ax2. And

Here, the main body portion 23 has a thick portion 231 and a thin portion 30 that is thinner than the thick portion 231. The thin wall portion 30 has a first screw hole 241 provided in the first leg portion 24 and a second screw hole 242 provided in the second leg portion 25 in the outer circumferential surface of the body portion 23. It is provided along the circumferential line L1 (indicated by a chain double-dashed line). Specifically, the thin portion 30 is connected from an annular first peripheral edge portion 243 provided on the outer peripheral side of the first screw hole 241 to an annular second peripheral edge portion provided on the outer peripheral side of the second screw hole 242. It is provided.

As shown in FIG. 2, when the thickness of the thick portion 231 is T1 and the minimum thickness of the thin portion 30 is T2, the thickness T2 is smaller than the thickness T1. The distance T3 between the inner peripheral surface of the holding portion 40 and the upper surface of the second arm portion 222 along the second direction D2 is larger than the wall thicknesses T1 and T2. In the first embodiment, the outer peripheral surface of the main body 23 is broached, and in the cross-sectional shape of FIG. 2, the upper surface of the thin portion 30 is recessed in an arc shape toward the inner peripheral side. The thin portion 30 has substantially the same shape from the first peripheral portion 243 to the second peripheral portion. Note that, although not clearly shown in FIG. 2, the inner peripheral surface of the thin portion 30 has a shape of a protrusion protruding toward the inner peripheral side. This is because when the broaching process is performed on the outer peripheral surface of the main body portion 23, a load pressing toward the inner peripheral side is input to the main body portion 23, and the thin portion 30 is plastically deformed to protrude toward the inner peripheral side. This is because.

As shown in FIG. 2, the held portion 41 of the shaft 15 is provided with a first male serration 411 (male serration 410), an annular groove 412, and a second male serration 413 (male serration 410).

The first male serration 411 is provided at the end of the shaft 15 in the axial direction (first direction D1). The second male serrations 413 are arranged at a distance from the first male serrations 411 in the axial direction of the shaft 15 (first direction D1). The first male serration 411 and the second male serration 413 have the same tip circle diameter and root circle diameter. The annular groove 412 is arranged between the first male serration 411 and the second male serration 413. The diameter of the annular groove 412 is smaller than the diameter of the root circle of the first male serration 411 and the second male serration 413. The annular groove 412 is a smooth curved surface connected along the entire circumference of the shaft 15 in the circumferential direction. The upper surface of the annular groove 412 is recessed in an arc shape over the entire circumference toward the inner peripheral side. As shown in FIG. 2, in the state where the shaft 15 is held by the yoke 20, the annular groove 412 is arranged on the inner peripheral side of the thin portion 30 in the first direction D1, and one side of the thin portion 30 in the axial direction is arranged. A first male serration 411 is arranged on the inner peripheral side (left side of the paper of FIG. 2), and a second male serration is formed on the inner peripheral side of the other side (right side of the paper of FIG. 2) in the axial direction of the thin portion 30. 413 is arranged. Since the convex portion protrudes more toward the inner peripheral side than the inner peripheral surface of the thick portion 231, the convex portion enters the annular groove 412 of the shaft 15 to perform positioning of the shaft 15 in the axial direction (first direction D1). Be seen.

Next, a procedure for inserting the held portion 41 of the shaft 15 into the holding portion 40 of the yoke 20 will be described.

FIG. 5 is a sectional view showing a state before the shaft 15 is inserted into the yoke 20. FIG. 6 is a cross-sectional view showing the state of the initial stage of inserting the shaft 15 into the yoke 20. FIG. 7 is a cross-sectional view showing a state in which the shaft 15 has been inserted into the yoke 20.

As shown in FIG. 5, the axis of the yoke 20 and the axis of the shaft 15 are arranged concentrically, and the shaft 15 is moved to the left side of the paper surface of FIG. In addition, as shown in FIG. 5, the width W1 of the thin portion 30 is substantially the same as the width W2 of the annular groove 412 of the shaft 15.

As shown in FIG. 6, first, the first male serration 411 is inserted into the holding portion 40. A convex portion is formed on the inner peripheral side of the thin portion 30 and the inner diameter of the inner peripheral side of the thin portion 30 is smaller than the inner diameter of the inner peripheral surface of the thick portion 231. Therefore, in the state of FIG. 6, the first male serration 411 spreads the inner peripheral convex portion of the thin portion 30 to the outer peripheral side, whereby the portion of the shaft 15 of the first male serration 411 is radially centered. It That is, the shaft 15 moves in the radial direction in which the axis of the shaft 15 coincides with the axis of the main body 23.

Next, as shown in FIG. 7, when the shaft 15 is further moved to the left in the plane of FIG. 7, the annular groove 412 of the shaft 15 is arranged on the inner peripheral side of the thin portion 30. In this state, the convex portion on the inner peripheral side of the thin portion 30 enters the annular groove 412 to position the shaft 15 in the axial direction.

As described above, in the universal joint yoke 20 according to the first embodiment, the base portion including the U-shaped main body portion 23, and the first leg portion 24 and the second leg portion 25 (a pair of leg portions). 21 is provided. The holding portion 40 is provided with female serrations 401, and the held portion 41 is provided with male serrations 410. The main body portion 23 has a thick portion 231 and a thin portion 30 that is thinner than the thick portion 231.

When the flexural rigidity of the main body 23 is high, the amount of elastic deformation of the main body 23 due to the screw fastening becomes small. In this case, the contact area between the male serration 410 of the shaft 15 and the female serration 401 of the yoke 20 becomes small, and the teeth of the female serration 401 may be damaged. Here, the main body portion 23 includes a thick portion 231 and a thin portion 30 that is thinner than the thick portion 231. The thin portion 30 reduces the flexural rigidity of the body portion 23, and increases the amount of elastic deformation of the body portion 23 due to screw fastening. Further, since the thin portion 30 can be formed by forging, for example, the work of removing burrs that occurs when forming the opening by punching is reduced. Therefore, according to the present disclosure, the yoke 20 in which the post-processing work such as the removal of burrs is unlikely to occur and the flexural rigidity of the main body 23 is low is provided.

Each of the first leg portion 24 and the second leg portion 25 (a pair of leg portions) is provided with a first screw hole 241 and a second screw hole 242 (screw hole) through which a screw member is fastened. The thin portion 30 has a first screw hole 241 provided in the first leg portion 24 and a second screw hole 242 provided in the second leg portion 25 in the outer circumferential surface of the body portion 23. It is provided along the circumferential line L1.

When the first leg portion 24 and the second leg portion 25 approach each other by screw fastening, they are most located at a portion along the first circumferential direction line L1 that connects the first screw hole 241 and the second screw hole 242 in the circumferential direction. A large bending stress is applied. Therefore, by providing the thin portion 30 along the first circumferential direction line L1, the flexural rigidity of the main body portion 23 is further reduced, and the elastic deformation amount of the main body portion 23 due to the screw fastening is further increased. Therefore, damage to the teeth of the female serration 401 can be further prevented.

The thin portion 30 is provided so as to extend from the first peripheral edge portion 243 of the first screw hole 241 to the second peripheral edge portion of the second screw hole 242.

Since the thin portion 30 is provided so as to be connected from the first peripheral portion 243 of the first screw hole 241 to the second peripheral portion of the second screw hole 242, the length of the thin portion 30 along the first circumferential line L1 is It can be set longer.

[Second Embodiment]
Next, a second embodiment will be described. Portions having the same structure as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted. FIG. 8 is a perspective view showing a universal joint yoke 20A according to the second embodiment. FIG. 9 is a side view of FIG. FIG. 10 is a sectional view showing a universal joint yoke 20A according to the second embodiment.

The yoke 20A has a base portion 21A and an arm portion 22A. The base portion 21A has a main body portion 23A, a first leg portion 24, and a second leg portion 25.

The main body portion 23A has a thick portion 231A and a thin portion 30A having a smaller thickness than the thick portion 231A. The thin portion 30A has a first screw hole 241 provided in the first leg portion 24 and a second screw hole 242 provided in the second leg portion 25 in the outer circumferential surface of the body portion 23A. It is provided along the circumferential line L1 (indicated by a chain double-dashed line). The thin portion 30A extends from the peripheral edge of the first screw hole 241 to the peripheral edge of the second screw hole 242.

The arm portion 22A extends forward (first direction D1) from the base portion 21A. The arm portion 22A has a first arm portion 221A located on the left side of the paper surface of FIG. 8 and a second arm portion 222A located on the right side. The arm portion 22A has a first arm portion 221A and a second arm portion 222A that branch left and right from the base portion 21A and extend. A first bearing holding hole 221Aa is provided in the first arm portion 221A. A second bearing holding hole 222Aa is provided in the second arm portion 222A. The first bearing holding hole 221Aa and the second bearing holding hole 222Aa are arranged to face each other while being separated in the left-right direction (third direction D3).

As shown in FIG. 10, when the thickness of the thick portion 231A is T4 and the minimum thickness of the thin portion 30A is T5, the thickness T5 is smaller than the thickness T4. The distance T6 between the inner peripheral surface of the holding portion 40 and the upper surface of the root portion 223 of the arm portion 22A along the second direction D2 is larger than the wall thicknesses T4 and T5. Further, in the present embodiment, the first arm portion 221A and the second arm portion 222A branch in the left-right direction. Therefore, as is clear when comparing FIG. 2 and FIG. 10, the distance T6 is smaller than the distance T3.

As described above, in the universal joint yoke 20A according to the second embodiment, as shown in FIG. 10, in the second direction D2 between the inner peripheral surface of the holding portion 40 and the upper surface of the root portion 223 of the arm portion 22A. The along distance T6 is smaller than the distance T3 shown in FIG. 2 according to the first embodiment. Therefore, the flexural rigidity of the main body portion 23A is further reduced, and the elastic deformation amount of the main body portion 23A due to the screw fastening is further increased.

[Third Embodiment]
Next, a third embodiment will be described. The parts having the same structures as those in the first and second embodiments are designated by the same reference numerals and the description thereof will be omitted.

FIG. 11 is a perspective view showing a universal joint yoke 20B according to the third embodiment. FIG. 12 is a side view of FIG. FIG. 13 is a sectional view taken along the line AA of FIG.

In the present embodiment, the toothless portion 402 having no female serrations 401 is provided on a part of the inner peripheral surface of the main body portion 23B. Specifically, as shown in FIG. 13, in a state where the main body portion 23B (base portion 21B) is viewed from the first direction D1, the inner peripheral surface on one side in the third direction D3 with the axial center Ax1 of the main body portion 23B interposed therebetween is provided. The toothless portion 402 that is a smooth surface is provided, and the thin portion 30B is provided on the outer peripheral surface. In other words, the toothless portion 402, which is a smooth surface, is provided on the inner peripheral surface on the first leg 24 side (one side) with respect to the plane parallel to the axis Ax1 and passing through the slit 26. The thin portion 30B is provided on the outer peripheral surface on the side where the toothless portion 402 is provided with respect to the plane. The thin portion 30B extends from the first portion P1 to the second portion P2. The thickness of the thin portion 30B is smaller than the thickness of the thick portion 231B.

In the present embodiment, the toothless portion 402 is provided on one side of the first leg portion 24 side (left side of the paper surface of FIG. 13). The toothless portion 402 extends from the third portion P3 to the fourth portion P4. Further, the thin portion 30B is provided on the outer peripheral surface on the side where the toothless portion 402 is provided. The lower end portion (second portion P2) of the thin portion 30B and the upper end portion (third portion P3) of the toothless portion 402 are located at portions that are aligned in the radial direction. As shown in FIG. 13, the thin portion 30B extends along the circumferential direction over a region having a central angle of about 90°. The toothless portion 402 extends over a range in which the central angle in the circumferential direction is about 90°. As described above, the holding portion 40B includes the serration region in which the female serration 401 is provided and the toothless region in which the female serration 401 is not provided. A first screw hole 241 is provided in the first leg portion 24. A second screw hole 242 is provided in the second leg 25. It is desirable that the thin portion 30B extend along the circumferential direction over a region having a central angle of 60° or more and 90° or less.

As described above, in the universal joint yoke 20B according to the third embodiment, since the toothless portion 402 does not mesh with the male serration 410 of the shaft 15, the portion of the toothless portion 402 is located more than the portion of the female serration 401. The tightening force for tightening the shaft 15 is lower. Therefore, by disposing the toothless portion 402 and the thin portion 30B on the side of the first leg 24 that is the same side on one side in the third direction D3 that sandwiches the axis Ax1 of the body 23B, the body portion 23B Flexural rigidity is further reduced.

[Fourth Embodiment]
Next, a fourth embodiment will be described. The parts having the same structures as those of the first to third embodiments are designated by the same reference numerals and the description thereof will be omitted.

FIG. 14 is a perspective view showing a universal joint yoke 20C according to the fourth embodiment. FIG. 15 is a side view of FIG. 16 is a sectional view taken along line BB of FIG.

In the present embodiment, the toothless portion 402 having no female serrations 401 is provided on a part of the inner peripheral surface of the main body portion 23C. Specifically, as shown in FIG. 16, in a state where the main body portion 23C (base portion 21C) is viewed from the first direction D1, the inner peripheral surface on one side in the third direction D3 across the axis Ax1 of the main body portion 23C is provided. The toothless portion 402, which is a smooth surface, is provided, and the thin portion 30C is provided on the outer peripheral surface. In other words, the toothless portion 402 that is a smooth surface is provided on the inner peripheral surface on the second leg 25 side (one side) with respect to the plane parallel to the axis Ax1 and passing through the slit 26. The thin portion 30C is provided on the outer peripheral surface on the side where the toothless portion 402 is provided with respect to the plane. The thin portion 30C extends from the fifth portion P5 to the sixth portion P6. The thickness of the thin portion 30C is smaller than the thickness of the thick portion 231C. In the present embodiment, the toothless portion 402 is provided on one side (on the right side of the paper surface of FIG. 16) on the second leg 25 side.

The toothless portion 402 extends from the seventh portion P7 to the eighth portion P8. Further, a thin portion 30C is provided on the outer peripheral surface on the side where the toothless portion 402 is provided. The lower end portion (sixth portion P6) of the thin portion 30C and the upper end portion (seventh portion P7) of the toothless portion 402 are located at the portions aligned in the radial direction. As shown in FIG. 16, the thin portion 30C extends along the circumferential direction over a region having a central angle of about 90°. The toothless portion 402 extends over a range in which the central angle in the circumferential direction is about 90°. As described above, the holding portion 40C includes the serration region in which the female serrations 401 are provided and the toothless region in which the female serrations 401 are not provided. A first screw hole 241 is provided in the first leg portion 24. A second screw hole 242 is provided in the second leg 25. It is desirable that the thin portion 30C extends along the circumferential direction over a region having a central angle of 60° or more and 90° or less.

As described above, in the universal joint yoke 20C according to the fourth embodiment, since the toothless portion 402 does not mesh with the male serration 410 of the shaft 15, the portion of the toothless portion 402 is located more than the portion of the female serration 401. The tightening force for tightening the shaft 15 is lower. Therefore, by disposing the toothless portion 402 and the thin portion 30C on the side of the second leg 25 that is the same side on one side in the third direction D3 across the axis Ax1 of the body 23C, the body portion 23C Flexural rigidity is further reduced.

Although the embodiment has been described above, the embodiment is not limited to the contents described above. For example, although the thin portions 30, 30A, 30B, 30C are provided along the first circumferential direction line L1, they may be provided at positions displaced from the first circumferential direction line L1 in the first direction D1.

15 Shafts 20, 20A, 20B, 20C Yoke (Yoke for universal joint)
21, 21A, 21B, 21C Base 22, 22A Arms 23, 23A, 23B, 23C Main body 231, 231A, 231B, 231C Thick part 24 First leg (a pair of legs)
241 1st screw hole 242 2nd screw hole 243 1st peripheral part 25 2nd leg part (a pair of leg part)
30, 30A, 30B, 30C Thin portion 40 Holding portion 401 Female serration 402 Missing tooth portion 41 Held portion 410 Male serration D1 First direction D2 Second direction D3 Third direction L1 First circumferential line

Claims (4)

A held portion of the shaft is inserted on the inner peripheral side, and a main body portion that covers a part of the held portion in the circumferential direction,
A pair of legs arranged at both ends of the main body in the circumferential direction and held in a state of being close to each other by screw fastening,
Equipped with
Female serrations are provided on the main body,
The held portion is provided with a male serration that meshes with the female serration,
The main body portion has a thick wall portion and a thin wall portion that is thinner than the thick wall portion and is disposed on the opposite side of the slit between the pair of leg portions with the axial center of the main body portion interposed therebetween. And, a universal joint yoke. Each of the pair of legs is provided with a screw hole through which a screw member penetrates and is fastened.
The thin portion has a first screw hole provided on one of the pair of leg portions and a second screw hole provided on the other second leg portion on the outer peripheral surface of the main body portion; The yoke for universal joint according to claim 1, which is provided on a first circumferential line that connects the two in the circumferential direction. The yoke for universal joint according to claim 2, wherein the thin portion is provided so as to be connected from a first peripheral edge portion of the first screw hole to a second peripheral edge portion of the second screw hole. The main body portion or the leg portion includes a toothless portion that is a smooth surface on an inner peripheral surface on one side with respect to a plane that is parallel to the axis and passes through the slit,
The yoke for a universal joint according to claim 2 or 3, wherein the thin portion is provided on an outer peripheral surface on a side where the toothless portion is provided with respect to the plane.

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