JP6673309B2 - Torque transmission shaft - Google Patents

Description

  The present invention relates to a torque transmission shaft incorporated in a steering device for an automobile or the like.

  FIG. 9 shows a conventionally known automobile steering device described in JP-A-2017-25959. The steering device includes a steering wheel 1, a steering shaft 2, a steering column 3, a pair of universal joints 4a and 4b, an intermediate shaft 5, a steering gear unit 6, and a pair of tie rods 7. .

  The steering wheel 1 is attached to a rear end of a steering shaft 2 rotatably supported inside a steering column 3. The front end of the steering shaft 2 is connected to a pinion shaft 8 of a steering gear unit 6 via a pair of universal joints 4a, 4b and an intermediate shaft 5. Then, by converting the rotation of the pinion shaft 8 into a linear motion of a rack (not shown), the pair of tie rods 7 are pushed and pulled, and a steering angle corresponding to the operation amount of the steering wheel 1 is given to the steered wheels. Note that the front-back direction refers to the front-back direction of the vehicle body to which the steering device is assembled.

  The universal joints 4a and 4b connect the steering shaft 2 and the intermediate shaft 5, and the intermediate shaft 5 and the pinion shaft 8, which are rotary shafts that do not exist on the same straight line, so that torque can be transmitted to each other. As described in Japanese Patent Application Publication No. 2011-220398, a cross shaft type universal joint having a pair of yokes and a cross shaft has been used.

JP 2017-25964 A JP 2011-220398 A

  By the way, in a steering device mounted on a large vehicle, the distance from the steering shaft to the steering gear unit is long. Therefore, a plurality of shafts (torque transmission shafts) are connected to each other to form an intermediate shaft, or another shaft (a so-called extension) is provided between a yoke forming a universal joint and a shaft such as a steering shaft or a pinion shaft. Shaft).

  FIG. 10 shows the torque transmission shaft 9 constituting the intermediate shaft considered by the present inventors. The torque transmission shaft 9 is disposed between a first shaft 10 having a bellows portion and a second shaft 11, and is connected to the first shaft 10 and the second shaft 11 so as to be capable of transmitting torque. The torque transmission shaft 9 is provided with a male serration 12 corresponding to a connection portion on an outer peripheral surface of one end in the axial direction, and a female serration 13 on an inner peripheral surface of the other end in the axial direction. The other end of the torque transmission shaft 9 in the axial direction is integrally provided with a clamp portion 14 for reducing the diameter of the other end of the torque transmission shaft 9 in the axial direction. Specifically, a discontinuous portion is provided at one location in the circumferential direction at the other end in the axial direction of the torque transmission shaft 9, and a pair of flange portions 15 are provided on both sides of the discontinuous portion. The flange portion 15 is provided with a mounting hole 16 for inserting a fastening member (not shown).

  One end of the torque transmission shaft 9 in the axial direction is inserted inside the other end of the first shaft 10 in the axial direction, and the male serration 12 is engaged with the female serration 17 formed on the inner peripheral surface of the first shaft 10. Let it. Further, the torque transmission shaft 9 and the first shaft 10 are fixed by welding.

  One axial end of the second shaft 11 is inserted inside the other axial end of the torque transmission shaft 9, and the male serration 18 formed on the outer peripheral surface of the second shaft 11 is engaged with the female serration 13. Let it. Further, the outer peripheral surface of the second shaft 11 is strongly tightened by the inner peripheral surface of the torque transmission shaft 9 by screwing the distal end of the tightening member into the mounting hole 16 or a nut (not shown).

  The torque transmission shaft 9 having the above-described configuration is often manufactured by cold forging, and has higher shape accuracy and dimensional accuracy than that manufactured by hot forging, but the flow of the metal material is complicated. In this case, it is difficult to ensure a high degree of coaxiality between the male serrations 12 and the female serrations 13 provided at both ends in the axial direction of the torque transmission shaft 9. Further, since the torque transmission shaft 9 and the first shaft 10 are fixed by welding, the coaxiality between the torque transmission shaft 9 and the first shaft 10 tends to be low due to thermal deformation or the like. Therefore, as shown in FIG. 10C, the whirling of the shaft (first shaft 10 or second shaft 11) connected to the torque transmission shaft 9 may increase. As a result, there is a possibility that a part of the steering device may generate abnormal noise due to whirling (sliding noise in the rotating direction, stick-slip vibration noise, etc.).

  The present invention has been made in view of the above circumstances, and an object of the present invention is to realize a structure capable of suppressing whirling of a shaft connected to a torque transmission shaft.

The torque transmission shaft of the present invention includes a shaft and a clamp.
The shaft is formed in a hollow shape, and a connection portion is provided at one end in the axial direction so as to be capable of transmitting torque to another member, and the other end in the axial direction extends in the axial direction. And an engaging cylinder portion having the circumferential end surfaces on both sides of the slit as shaft-side engaging surface portions, respectively. The shaft is provided with a female serration at the other end in the axial direction of the inner peripheral surface.
The clamp is formed, for example, in a partially-cylindrical shape, and is externally fitted to the engagement cylinder to reduce the diameter of the other end of the shaft in the axial direction. The clamp is provided with a discontinuous portion at one circumferential position, and a pair of flange portions each having a mounting hole for inserting a fastening member on both sides of the discontinuous portion. Have been. Further, in the clamp, a pair of clamp-side engaging surfaces are provided on an inner peripheral surface of an insertion hole into which the shaft is inserted.
In particular, in the torque transmission shaft of the present invention, the pair of shaft-side engaging surfaces and the pair of clamp-side engaging surfaces are circumferentially engaged with each other.
Further, in the torque transmission shaft according to the present invention, the pair of clamp-side engaging surface portions may be arranged so that the pair of clamp-side engaging surfaces are perpendicular to the center axis of the insertion hole and the center axis of the tightening member. It is arranged between the mounting hole.

  According to the present invention, a wide portion having a larger width dimension than a portion adjacent to one side in the axial direction is provided at an opening end portion which is the other end portion in the axial direction of the slit, and the first portion is provided on both sides of the wide portion. A pair of shaft-side engagement surfaces may be provided.

  According to the present invention, a stress relaxing portion having a larger width dimension than a portion adjacent to the other side in the axial direction can be provided at a far end portion which is one axial end portion of the slit. As the stress relaxation portion, a shape having an inner surface formed by a concave curved surface, such as a circular shape, an elliptical shape, or a drop shape, can be adopted.

In the present invention, a plastically deformable portion formed by plastically deforming the shaft is provided on the other axial end surface of the shaft, and the plastically deformable portion can be pressed against the clamp.
As the plastic deformation portion, for example, a caulking deformation portion formed by caulking the other end surface in the axial direction of the shaft can be adopted.

  In the present invention, the pair of shaft-side engagement surfaces can be present on the same virtual plane.

  In the present invention, a step surface facing the other side in the axial direction is provided between the engagement cylinder portion and a portion adjacent to one side in the axial direction of the engagement cylinder portion in the outer peripheral surface of the shaft. Can be. Then, by abutting the clamp against the step surface, positioning of the clamp with respect to the shaft in the axial direction can be achieved.

  In the present invention, the outer peripheral surface of the engagement cylinder portion can be a cutting surface.

In the present invention, the connection portion may be a forked yoke portion forming a universal joint.
Alternatively, the connection portion may be a serration portion or a spline portion, or a key engagement portion.

  According to the present invention, whirling of a shaft connected to a torque transmission shaft can be suppressed.

FIG. 1 is a perspective view of a torque transmission shaft according to a first example of the embodiment. FIG. 2 is an exploded perspective view of a torque transmission shaft according to a first example of the embodiment. FIG. 3 is a side view of the torque transmission shaft according to the first example of the embodiment. FIG. 4 is an end view of the torque transmission shaft according to the first example of the embodiment as viewed from the other side in the axial direction. FIG. 5A is a view corresponding to a cross section taken along line AA of FIG. 3, and FIG. 5B is a cross-sectional view of a clamp shown as a comparative example. FIG. 6 is an exploded perspective view showing a torque transmission shaft according to a first example of the embodiment and a shaft connected to the torque transmission shaft. FIG. 7 is a cross-sectional view showing a connection state between a torque transmission shaft according to a first example of the embodiment and a shaft connected to the torque transmission shaft. FIG. 8 is a perspective view showing a shaft constituting a torque transmission shaft according to a second example of the embodiment. FIG. 9 is a partial cross-sectional side view showing a conventionally known steering device. FIG. 10A is a cross-sectional view showing a state where the torque transmission shaft previously considered by the present inventors is connected to the first shaft and the second shaft, respectively, and FIG. FIG. 10C is a schematic diagram for explaining a state in which whirling occurs on the first axis and the second axis.

[First Example of Embodiment]
A first example of the embodiment will be described with reference to FIGS.
The torque transmission shaft 19 of the present embodiment can be torque-transmitted to a steering shaft and an intermediate shaft, or an intermediate shaft and a pinion shaft, which are built-in, for example, in a steering apparatus of a large automobile and are rotating shafts that do not exist on the same straight line. Used to connect to.

  The torque transmission shaft 19 is composed of a hollow cylindrical shaft 20 and a clamp 21 having a substantially cylindrical shape (substantially U-shape), which are formed separately from each other. In the following description, the axial direction refers to the axial direction of the torque transmission shaft 19, unless otherwise specified. Also, one end in the axial direction refers to the left end in FIGS. 1 to 3, 6 and 7, and the other end in the axial direction refers to the right end in FIGS. 1 to 3, 6 and 7. Say.

  The shaft 20 is manufactured by performing forging (cold forging or hot forging), cutting, or the like on a material such as a carbon steel cast steel material (SC material). The shaft 20 includes a forked yoke portion 22 corresponding to a connection portion provided at one end in the axial direction, and a cylindrical portion 23 provided at the other end to the intermediate portion in the axial direction.

  The yoke portion 22 constitutes a cross-shaft universal joint, and includes a pair of arm portions 24a and 24b. Each of the arms 24a and 24b is provided so as to extend to one axial side from two diametrically opposite sides of one axial end of the cylindrical portion 23. A circular hole 25 is formed coaxially at the tip of each of the arms 24a and 24b. A bearing cup and a needle (not shown) are arranged inside the circular hole 25, and a shaft constituting a cross shaft is rotatably supported.

  The cylindrical portion 23 constituting the shaft 20 is entirely formed in a hollow cylindrical shape, and includes, in order from one axial side, a large-diameter cylindrical portion 26, a conical cylindrical portion 27, and a small-diameter cylindrical portion 28. .

  The large-diameter tube portion 26 is formed in a stepped cylindrical shape in the illustrated example, and the other end in the axial direction is connected to one end in the axial direction of the conical tube portion 27. The outer diameter and the inner diameter of the large-diameter cylindrical portion 26 are larger than the outer diameter and the inner diameter of the small-diameter cylindrical portion 28.

  The conical cylindrical portion 27 is formed in a partially conical cylindrical shape in which the outer diameter and the inner diameter decrease toward the other side in the axial direction, and the other end in the axial direction is the one end in the axial direction of the small diameter cylindrical portion 28. Is connected to

  The small-diameter cylindrical portion 28 is formed in a cylindrical shape, and is provided in a range from the other end in the axial direction of the shaft 20 to an intermediate portion. At the other end in the axial direction of the small-diameter cylindrical portion 28, an engaging cylindrical portion 29 having an outer diameter smaller than that of a portion adjacent to one side in the axial direction is provided. In this example, the engaging cylinder 29 is formed by cutting the outer peripheral surface of the other end in the axial direction of the small-diameter cylinder 28. For this reason, the outer peripheral surface of the engagement cylindrical portion 29 is a cutting surface. Further, at the axially intermediate portion (portion near the other axial end of the shaft 20) of the outer peripheral surface of the small-diameter cylindrical portion 28, the engagement cylindrical portion 29 and a portion adjacent to one side in the axial direction of the engaging cylindrical portion 29 are formed. A substantially annular (C-shaped) step surface 30 facing the other side in the axial direction is provided therebetween. As will be described later, when the clamp 21 is externally fitted to the engagement cylindrical portion 29, one end face in the axial direction of the clamp 21 is abutted against the step surface 30 to position the clamp 21 relative to the shaft 20 in the axial direction. I try to plan. A female serration 31 is formed on the inner peripheral surface of the small-diameter cylindrical portion 28 over its entire length. As shown in FIGS. 6 and 7, an end of a shaft 45 such as a steering shaft or a pinion shaft is inserted inside the small-diameter cylindrical portion 28, and a male serration formed on an outer peripheral surface of the end of the shaft 45 is provided. The serration 46 is engaged with the female serration 31.

  An axially extending slit 32 is formed in a portion of the small-diameter cylindrical portion 28 where a position (phase) in the circumferential direction coincides with one arm portion 24a constituting the yoke portion 22. The slit 32 allows the inner and outer peripheral surfaces of the small-diameter cylindrical portion 28 to communicate with each other. The back end, which is one end in the axial direction of the slit 32, is located at the axially intermediate portion of the small-diameter cylindrical portion 28, and the other end of the slit 32 in the axial direction is the axis of the small-diameter cylindrical portion 28 (the shaft 20). It is open at the other end edge in the direction.

  At the other end of the slit 32 in the axial direction, a portion aligned with the engagement cylinder portion 29 in the axial direction has a larger width dimension (for example, three to three times) than a portion adjacent to one side in the axial direction (axial middle portion). A wide portion 33 which is about 6 times larger) is provided. In other words, a wide portion 33 of the slit 32 extending in the axial direction is formed in a portion of the engagement cylinder portion 29 where the circumferential position coincides with one arm portion 24a constituting the yoke portion 22. For this reason, the engagement cylinder portion 29 has a substantially C-shape when viewed from the axial direction, and has a flat surface-like shaft-side engagement surface portion 34 on each of both circumferential end surfaces on both sides of the wide portion 33. Is provided. In this example, the pair of shaft-side engagement surface portions 34 are located on the same virtual plane parallel to the central axis of the shaft 20. Such a pair of shaft-side engaging surface portions 34 are simultaneously formed by cutting.

  On the other hand, the rear end portion, which is one end portion in the axial direction of the slit 32, has a substantially circular shape in a plan view in which the width dimension is larger than that of the portion adjacent to the other side in the axial direction (axial middle portion). A stress relaxation section 35 is provided. Therefore, the slit 32 is composed of a stress relieving portion 35 at one end in the axial direction, a wide portion 33 at the other end in the axial direction, and an intermediate portion in the axial direction between the wide portion 33 and the stress relieving portion 35. I have.

  As described above, by providing the slit 32 at the other end in the axial direction of the shaft 20, the other end in the axial direction of the shaft 20 (the other half in the axial direction of the small-diameter cylindrical portion 28) can be reduced in diameter. . In addition, by providing the stress relaxation portion 35 at the back end of the slit 32, when the diameter of the shaft 20 is reduced, damage such as a crack is prevented from occurring at the back end of the slit 32 where stress tends to concentrate. I have.

  The clamp 21 is fitted around the other end of the shaft 20 in the axial direction to reduce the diameter of the other end of the shaft 20 in the axial direction. Specifically, the clamp 21 is externally fitted to the engagement cylinder 29 that forms the shaft 20 to reduce the diameter of the other half of the small-diameter cylinder 28 in the axial direction. Such a clamp 21 is formed by subjecting a material having a higher hardness than the material forming the shaft 20, for example, to a material such as S35C (carbon steel for machine structure) by hot forging or cutting, or for example, to S10C or It is manufactured by subjecting a material such as S15C (carbon steel for machine structure) to cold forging that causes work hardening.

  The clamp 21 is entirely formed in a partially cylindrical shape (substantially U-shape), and includes a semi-cylindrical base 36 and a substantially rectangular plate-shaped one provided at both ends in the circumferential direction of the base 36. And a pair of flange portions 37. Further, a discontinuous portion 38 is provided at one circumferential position of the clamp 21 located between the pair of flange portions 37. Therefore, a pair of flange portions 37 is provided on both sides of the discontinuous portion 38. Further, in a state where the clamp 21 is fixed to the engagement cylindrical portion 29, the circumferential positions of the discontinuous portion 38 and the slit 32 (the wide portion 33) provided in the shaft 20 coincide with each other.

  The clamp 21 is provided with an insertion hole 39 for inserting the engagement cylinder 29 of the shaft 20. The insertion hole 39 is constituted by an inner peripheral surface of the base 36 and a radially inner side surface of the pair of flange portions 37, and the contour of the inner peripheral surface includes an arc portion and a pair of linear portions. It is substantially D-shaped. In this example, portions (linear portions) formed by the radially inner side surfaces of the pair of flange portions 37 on the inner peripheral surface of the insertion hole 39 are each a flat surface-shaped clamp-side engaging surface portion 40. The inner diameter (width) of the insertion hole 39 in the free state of the clamp 21 is equal to or slightly larger than the outer diameter (width) of the engagement cylinder 29 in the free state.

  Mounting holes 41a and 41b are formed coaxially in portions of the pair of flange portions 37 that match each other. These mounting holes 41 a and 41 b are formed at positions twisted with respect to the center axis of the insertion hole 39. One of the mounting holes 41a and 41b is a through hole, and the other mounting hole 41b is a screw hole.

  In this example, the inner peripheral surface of the insertion hole 39 is constituted by the radially inner side surfaces (clamp-side engaging surface portions 40) of the pair of flange portions 37. For this reason, FIG. 5A showing the present embodiment is compared with FIG. 5A in which the inner peripheral surface of the insertion hole 39a is not formed by the radially inner side surface of the flange portion 37a (having no flat surface-shaped clamp-side engaging surface portion 40). As is clear from comparison with FIG. 5B showing an example, in this example, it is easy to secure the axial lengths of the mounting holes 41a and 41b. For this reason, in the clamp 21 of this example, as in the structure of the comparative example of FIG. 5B, in order to secure the engagement dimension (effective screw length), the widthwise outer surface of the flange portion 37a is connected to the base portion 36a. There is no need to project outward in the width direction with respect to the outer peripheral surface. Therefore, the dimension h between the widthwise outer surfaces of the pair of flange portions 37 is smaller than the same dimension H of the structure of the comparative example (h <H). Therefore, the outer shape (physique) of the clamp 21 can be reduced, and the weight can be reduced. Further, when the torque transmission shaft 19 is rotated, a circular locus (swing circle) drawn by the outer peripheral edge of the clamp 21 can be reduced.

  In particular, in this example, the other end of the shaft 20 in the axial direction is inserted into the insertion hole 39 of the clamp 21, and the clamp 21 is externally fitted to the engagement cylindrical portion 29, and the pair of shaft-side engagement surface portions 34 is provided. The shaft 20 and the clamp 21 are prevented from rotating relative to each other by engaging (abutting) the and the pair of clamp-side engaging surfaces 40 in the circumferential direction. Further, in a state where the one end face in the axial direction of the clamp 21 is abutted against the step surface 30, a plurality of places (three places in the illustrated example) in the circumferential direction of the other end face in the axial direction of the shaft 20 are deformed by caulking. And a caulking deformation portion 42 which is a plastic deformation portion. Then, these caulking deformed portions 42 are pressed against the other end face in the axial direction of the base 36 constituting the clamp 21. This prevents the shaft 20 and the clamp 21 from being relatively displaced in the axial direction.

  To manufacture the torque transmission shaft 19 having the above-described configuration, first, the shaft 20 is inserted into the insertion hole 39 of the clamp 21 from the other end in the axial direction. At this time, by positioning the pair of shaft-side engaging surface portions 34 and the pair of clamp-side engaging surface portions 40 in the circumferential direction, positioning (phase matching) of the shaft 20 and the clamp 21 in the circumferential direction is performed. Do. Next, the shaft 20 and the clamp 21 are relatively moved in the axial direction until the end surface on one axial side of the clamp 21 abuts on the step surface 30. Next, a caulking deformation portion 42 is formed on the other axial end surface of the shaft 20 to prevent the clamp 21 from slipping out of the engagement cylindrical portion 29 of the shaft 20 to the other axial side. Finally, a tightening bolt 43 as a tightening member is inserted into the pair of mounting holes 41a and 41b. Specifically, the base portion of the tightening bolt 43 is inserted without looseness into the inside of the one mounting hole 41a, which is a through hole, and the distal end of the tightening bolt 43 is inserted into the other screw hole. Screw it into the mounting hole 41b.

  When the torque transmission shaft 19 is in use, the yoke portion 22 provided at one axial end of the torque transmission shaft 19 is combined with another yoke (not shown) and a cross shaft to provide the torque transmission shaft 19 with the other yoke. Connected to a shaft such as an intermediate shaft that can transmit torque. On the other hand, a shaft 45 such as a steering shaft or a pinion shaft is inserted into the inside of the small-diameter cylindrical portion 28, and the male serration 46 formed on the outer peripheral surface of the shaft 45 is attached to the inner peripheral surface of the small-diameter cylindrical portion 28. The serrations are engaged with the female serrations 31 formed in the above. This prevents the relative rotation between the torque transmission shaft 19 and the shaft 45. Further, the intermediate portion of the tightening bolt 43 is inserted into an annular groove 47 formed on the outer peripheral surface of the distal end portion of the shaft 45 so as to cross the male serration 46 in the circumferential direction, and the annular groove 47 is tightened. The bolt 43 is keyed. This prevents the shaft 45 and the torque transmission shaft 19 from moving relative to each other in the axial direction. Also, by increasing the screwing amount of the tightening bolt 43 to reduce the width of the discontinuous portion 38 and reduce the diameter of the small-diameter cylindrical portion 28, the outer peripheral surface of the shaft 45 is formed by the inner peripheral surface of the small-diameter cylindrical portion 28. Tighten strongly. Thereby, the torque transmission shaft 19 and the shaft 45 such as a steering shaft and a pinion shaft are coupled so as to be able to transmit torque.

According to the torque transmission shaft 19 of the present example having the above-described configuration, the whirling of the shaft connected to the torque transmission shaft 19 can be suppressed.
That is, the torque transmission shaft 19 of the present embodiment does not include the clamp 21 integrally with the shaft 20, but instead of the pair of clamp-side engaging surface portions 40 provided on the clamp 21 and the pair of clamp-side engagement surface portions 40 provided on the shaft 20. The relative displacement of the shaft 20 and the clamp 21 in the circumferential direction is prevented by engaging the shaft-side engaging surface portion 34 with each other in the circumferential direction. Further, by forming a caulking deformation portion 42 on the other end surface in the axial direction of the shaft 20 in a state where one end surface in the axial direction of the clamp 21 abuts against the step surface 30, the axial direction between the shaft 20 and the clamp 21 is formed. Prevents relative displacement. In this example, the clamp 21 is fixed to the shaft 20 in this manner. For this reason, a high degree of coaxiality between the yoke portions 22 provided at both axial end portions of the shaft 20 and the female serrations 31 can be ensured. Further, since the shaft 20 and the yoke portion 22 are integrally provided, the shaft 20 and the yoke portion 22 are not affected by thermal deformation during welding, and a high degree of coaxiality of the yoke portion 22 with the shaft 20 (the cylindrical portion 23) can be ensured. Therefore, whirling of the shaft connected to the yoke portion 22 and the shaft 45 connected to the female serration 31 can be suppressed. As a result, it is possible to prevent generation of an abnormal noise (such as a sliding noise in the rotating direction and a stick-slip vibration noise) due to the whirling of the shaft in a part of the steering device. Further, since the shaft 20 is formed in a hollow shape, it is advantageous in reducing the weight of the torque transmission shaft 19 as a whole. Further, since the outer peripheral surface of the engagement cylindrical portion 29 is a cutting surface, the shape accuracy and dimensional accuracy of the outer peripheral surface can be improved, and the combination accuracy with the clamp 21 can be improved. Further, since the shape accuracy of the caulking deformation portion 42 can be stabilized, the dimensional accuracy with the clamp 21 fixed can be improved.

[Second Example of Embodiment]
A second example of the embodiment will be described with reference to FIG.
In this example, the outer diameter of the small-diameter cylindrical portion 28 is constant over the entire length in the axial direction. For this reason, between the engagement cylinder 29a provided with the shaft-side engagement surface 34 on both ends in the circumferential direction, and a portion of the engagement cylinder 29a adjacent to one axial side, respectively. It does not have an annular step surface as in the first example (see FIG. 2). However, in this example, each of the shaft-side engaging surface portions 34 has a contact surface 44 that is partially arc-shaped and faces the other side in the axial direction in a state of being connected to one axial end portion of the shaft-side engaging surface portion 34. For this reason, it is possible to position the clamp 21 (see FIG. 1) in the axial direction with respect to the shaft 20 by using the respective abutting surfaces 44. Further, in order to prevent stress from being concentrated on a continuous portion between the shaft-side engaging surface portion 34 and the abutting surface 44, the continuous portion may be subjected to a rounding process or a chamfering process.
Other configurations and operational effects are the same as those of the first embodiment.

  In practicing the present invention, the circumferential position, number, and shape of the plastically deformed portions (caulking deformed portions) formed on the other axial end surface of the shaft are not limited to the structures described in the embodiments. Further, when implementing the present invention, the circumferential position of the slit formed in the shaft is not limited to the position shown in each example of the embodiment. Further, the number of slits is not limited to one, and a plurality of slits can be provided. Further, the shape of the stress relaxation portion formed at the innermost end of the slit is not limited to the shape shown in each example of the embodiment, and other shapes such as an elliptical shape and a drop shape can be adopted.

  Further, in each example of the embodiment, an example in which a yoke portion is provided as a connection portion at one end portion in the axial direction of the shaft has been described, but when the present invention is implemented, a serration portion or a yoke portion is used instead of the yoke portion. An uneven portion in the circumferential direction such as a spline portion or a key engaging portion may be provided. Further, a pair of mounting holes provided in the clamp may be respectively formed as through holes and used in combination with a nut.

DESCRIPTION OF SYMBOLS 1 Steering wheel 2 Steering shaft 3 Steering column 4a, 4b Universal joint 5 Intermediate shaft 6 Steering gear unit 7 Tie rod 8 Pinion shaft 9 Torque transmission shaft 10 First shaft 11 Second shaft 12 Male serration 13 Female serration 14 Clamp part 15 Flange part 16 Mounting Hole 17 Female Serration 18 Male Serration 19 Torque Transmission Shaft 20 Shaft 21 Clamp 22 Yoke 23 Tube 24a, 24b Arm 25 Round Hole 26 Large Diameter Tube 27 Conical Tube 28 Small Diameter Tube 29, 29a Engagement Tube Part 30 Stepped surface 31 Female serration 32 Slit 33 Wide part 34 Shaft side engaging surface part 35 Stress relief part 36, 36a Base part 37, 37a Flange part 38 Discontinuous part 39 Insertion hole 40 Clamp side engaging surface part 41a, 4 b mounting hole 42 swaged deformable portion 43 fastening bolt 44 abutting surface 45 the axis 46 male serration 47 annular groove

Claims (8)

A connection portion is provided at one end in the axial direction so as to be capable of transmitting torque to another member, and a slit extending in the axial direction is provided at the other end in the axial direction. A hollow shaft provided with an engagement cylinder portion having both ends in the circumferential direction present on both sides as shaft-side engagement surfaces, and a female serration provided on the other end in the axial direction of the inner peripheral surface,
The other end of the shaft in the axial direction is reduced in diameter by being externally fitted to the engagement cylinder portion, and a discontinuous portion is provided at one location in the circumferential direction, and on both sides of the discontinuous portion, A pair of flange portions each having a mounting hole for inserting a tightening member are provided, and a pair of clamp-side engaging surface portions are provided on an inner peripheral surface of the insertion hole into which the engaging cylinder portion is inserted. With a clamp,
The pair of shaft-side engagement surface portions and the pair of clamp-side engagement surface portions are respectively circumferentially engaged ,
The pair of clamp-side engaging surfaces are disposed between the central axis of the insertion hole and the mounting hole in directions perpendicular to the central axis of the insertion hole and the central axis of the fastening member. ,
Torque transmission shaft.   At the other end in the axial direction of the slit, a wide portion having a larger width dimension than a portion adjacent to one side in the axial direction is provided, and the pair of shaft side engagements are provided on both sides of the wide portion. The torque transmission shaft according to claim 1, wherein a surface portion is provided.   The stress relief portion having a larger width dimension than a portion adjacent to the other side in the axial direction is provided at a rear end portion which is one axial end portion of the slit. The torque transmission shaft described in the section.   The plastically deformed portion formed by plastically deforming the shaft is provided on the other axial end surface of the shaft, and the plastically deformed portion is pressed against the clamp. The torque transmission shaft described in the section.   The torque transmission shaft according to any one of claims 1 to 4, wherein the pair of shaft-side engagement surface portions are on the same virtual plane.   Of the outer peripheral surface of the shaft, a step surface facing the other side in the axial direction is provided between the engagement cylinder portion and a portion adjacent to one side in the axial direction of the engagement cylinder portion, The torque transmission shaft according to any one of claims 1 to 5, wherein positioning of the clamp in the axial direction with respect to the shaft is achieved by abutting the clamp against a step surface.   The torque transmission shaft according to any one of claims 1 to 6, wherein an outer peripheral surface of the engagement cylinder portion is a cutting surface.   The torque transmission shaft according to any one of claims 1 to 7, wherein the connection portion is a yoke portion.

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