Rotation shaft, connection structure of such rotation shaft and clamp device, and steering device

Abstract

To provide a rotation shaft capable of enhancing a fastening force by means of a clamp device.SOLUTION: A pinion shaft 13 includes a connection part 20 which is to be inserted to a clamp device at an end part in axial direction. The connection part 20 has male serration parts 21a to 21c which are arranged on three portions separated at approximately equal intervals with respect to circumferential directions on an outer circumferential surface and are provided with male serration teeth 23, and teeth non-formation parts 22a to 22c which are respectively arranged between the male serration parts 21a to 21c themselves adjoining to each other, and are not provided with the male serration teeth 23. The teeth non-formation parts 22a to 22c are located on the inner side in radial directions from a teeth bottom circle of the male serration teeth 23.SELECTED DRAWING: Figure 15

Description

Technical Field

[0001] The present disclosure relates to a rotating shaft, a coupling structure between the rotating shaft and a clamping device, and a steering device including the rotating shaft.

Background Art

[0002] An automotive steering device is used to impart a steering angle to a steering wheel.

[0003] In a steering device, the rotation of a steering wheel is transmitted to a pinion shaft of a steering gear unit via a steering shaft, an intermediate shaft, etc. The rotation of the pinion shaft is converted into a linear motion of a rack shaft of the steering gear unit. Thereby, a steering angle corresponding to the rotation operation amount of the steering wheel is imparted to the steering wheel.

[0004] In a steering device, the ends of two non-coaxial rotating shafts such as a steering shaft and an intermediate shaft are connected via a universal joint so as to be torque-transmittable.

[0005] A universal joint includes a pair of yokes and a cross shaft.

[0006] The yoke constituting the universal joint is a kind of clamping device, and has a cylindrical base portion, a pair of flange portions, and a pair of arm portions connected to the cross shaft.

[0007] The base has an axially extending slit at one location in the circumferential direction and is configured to be able to reduce its diameter. The ends of rotating shafts such as a steering shaft and a pinion shaft are inserted inside the base. The pair of flange portions are provided on both sides of the slit in the circumferential direction. The pair of flange portions have mounting holes arranged coaxially. The yoke fixes the rotating shaft with the base by screwing and further tightening a bolt inserted through one mounting hole provided in one flange portion of the pair of flange portions into the other mounting hole provided in the other flange portion, and is fixed to the rotating shaft.

[0008] The yoke is roughly classified into a so-called open slit type yoke and a so-called closed slit type yoke according to the difference in the structure of the slit provided at the base.

[0009] The closed slit type yoke is more likely to ensure strength compared to the open slit type yoke, and thus is preferably used for applications that transmit high torque.

[0010] FIG. 28 shows an example of the conventional structure of the open slit type yoke 100a. FIG. 29 shows an example of the conventional structure of the closed slit type yoke 100b.

[0011] The open slit type yoke 100a has a slit 102a at one location in the circumferential direction of the base 101a, and the end portions on both sides in the axial direction are open ends. The closed slit type yoke 100b has a slit 102b at one location in the circumferential direction of the base 101b, and one end portion in the axial direction is a closed end and the other end portion in the axial direction is an open end.

[0012] The closed slit type yoke 100b has higher flexural rigidity and is more likely to have higher deformation resistance compared to the open slit type yoke 100a. Therefore, when bolts (not shown) are tightened with the same magnitude of torque, the tightening force of the closed slit type yoke 100b is more likely to be smaller than the tightening force of the open slit type yoke 100a.

[0013] When the closed slit type yoke 100b is incorporated into a column assist type electric power steering device where high torque is transmitted, due to insufficient tightening force, the end portion of the rotating shaft may slide finely with respect to the base 101b. As a result, damage such as fretting wear and fretting corrosion may progress on the female serration teeth provided on the inner peripheral surface of the base 101b and / or the male serration teeth provided on the outer peripheral surface of the rotating shaft.

[0014] In view of such circumstances, a technique for increasing the tightening force has been considered for a closed slit type yoke.

[0015] Japanese Patent Application Laid-Open No. 2022-15860 describes a technique for increasing the tightening force of a yoke by firmly combining female serration teeth provided on the inner peripheral surface of a thick portion deviated in the circumferential direction from a thin portion provided in a range including a portion approximately ±45 degrees deviated in the circumferential direction from the portion on the opposite side of the slit in the radial direction of the inner peripheral surface of the base portion with male serration teeth provided on the outer peripheral surface of the rotating shaft.

Prior Art Document

Patent Document

[0016]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0017] In the conventional structure described in Japanese Patent Application Laid-Open No. 2022-15860, it is necessary to form a cylindrical surface-shaped toothless portion on the inner peripheral surface of the base portion that constitutes a yoke having a more complex structure than the rotating shaft. For this reason, there may be problems such as an increase in the number of processing steps and an increase in processing costs. In addition, the strength of the base portion may be insufficient.

[0018] The problems described above are not limited to the coupling portion between the yoke and the rotating shaft that constitutes a universal joint that connects two rotating shafts not arranged coaxially, but also occur similarly in the coupling portion between a clamp device other than the yoke, such as a connecting device that connects two rotating shafts arranged coaxially, and the rotating shaft.

[0019] An object of the present disclosure is to provide a rotating shaft capable of increasing the tightening force by a clamp device.

Means for Solving the Problems

[0020] The rotating shaft according to one aspect of the present disclosure rotates around a central axis and has a connection portion that is inserted into a clamping device at an axial end portion.

[0021] The clamping device is not limited to a yoke having a pair of arm portions that constitute a universal joint, and includes a connecting device having a connecting portion having a structure other than the pair of arm portions as a connecting portion for connectably transmitting torque to other members, and a connecting device not having a connecting portion.

[0022] The connection portion has a male serration portion disposed at three locations on the outer peripheral surface at substantially equal intervals in the circumferential direction and provided with male serration teeth, and tooth non-forming portions disposed between the adjacent male serration portions in the circumferential direction and not provided with the male serration teeth.

[0023] The tooth non-forming portion is located radially inside the root circle of the male serration teeth.

[0024] In the rotating shaft according to one aspect of the present disclosure, the tooth non-forming portion is constituted by a plane.

[0025] When the tooth non-forming portion is constituted by a plane, the tooth non-forming portion can be arranged parallel to the central axis. Alternatively, the tooth non-forming portion can be arranged inclined with respect to the central axis.

[0026] In the rotating shaft according to one aspect of the present disclosure, one of the tooth non-forming portions has an engagement groove extending in a direction orthogonal to the central axis.

[0027] In the rotating shaft according to one aspect of the present disclosure, one of the male serration portions has, in addition to the male serration teeth, a tooth missing portion or a thick tooth having a tooth thickness larger than that of the male serration teeth.

[0028] In the rotating shaft according to one aspect of the present disclosure, the central angle of the male serration portion centered on the central axis is smaller than the central angle of the tooth non-forming portion centered on the central axis.

[0029] The central angle of the male serration portion centered on the central axis can also be made larger than the central angle of the tooth non-forming portion centered on the central axis, or the central angle of the male serration portion centered on the central axis and the central angle of the tooth non-forming portion centered on the central axis can be made the same size.

[0030] A first aspect of the coupling structure between the rotating shaft and the clamp device according to one aspect of the present disclosure includes the rotating shaft according to one aspect of the present disclosure and a clamp device into which the connecting portion is inserted. The clamp device has a substantially cylindrical base portion having female serration teeth on its inner peripheral surface and a pair of flange portions.

[0031] The base portion has an insertion hole extending in the axial direction and a slit extending in the axial direction and arranged at one location in the circumferential direction.

[0032] When the connecting portion is inserted into the insertion hole and the diameter of the base portion is reduced, a gap is formed between the female serration teeth and the tooth non-forming portion facing each other in the radial direction. Even when the male serration teeth and / or the female serration teeth are damaged, the female serration teeth and the tooth non-forming portion facing each other in the radial direction do not engage in the circumferential direction.

[0033] A second aspect of the coupling structure between the rotating shaft and the clamp device according to one aspect of the present disclosure includes the rotating shaft according to one aspect of the present disclosure and a clamp device into which the connecting portion is inserted. The clamp device has a substantially cylindrical base portion having female serration portions arranged at three positions spaced substantially equidistantly in the circumferential direction on its inner peripheral surface and provided with female serration teeth, and toothless engagement portions provided between adjacent female serration portions in the circumferential direction and not provided with the female serration teeth, and a pair of flange portions.

[0034] The base portion has an insertion hole extending in the axial direction and a slit disposed at one location in the circumferential direction and extending in the axial direction.

[0035] The toothless engagement portion projects radially inward beyond the tip circle of the female serration teeth.

[0036] With the connecting portion inserted into the insertion hole and the base portion having its diameter reduced, the toothless engagement portion and the tooth non-forming portion face each other with a minute gap therebetween, and when the male serration teeth and / or the female serration teeth are damaged, the toothless engagement portion and the tooth non-forming portion engage with each other in the circumferential direction.

[0037] The steering device according to one aspect of the present disclosure includes a shaft that rotates by operation of a steering wheel, and the shaft is a rotating shaft according to one aspect of the present disclosure. In this case, the shaft can be any one of a pinion shaft, a steering shaft, and an intermediate shaft that constitute a steering gear unit.

Advantages of the Invention

[0038] According to the rotating shaft according to one aspect of the present disclosure, the clamping force by the clamping device can be increased.

Brief Description of the Drawings

[0039]

Figure 1

Figure 2

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Figure 4

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Figure 6

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Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

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Figure 19

Figure 20

Figure 21

Figure 22

Figure 23

Figure 24

Figure 25

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Figure 27

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Figure 29

MODE FOR CARRYING OUT THE INVENTION

[0040] [First Example] The first example of the embodiment of the present disclosure will be described with reference to FIGS. 1 to 15.

[0041] This example is an example in which the rotation axis of one aspect of the present disclosure is applied to a pinion shaft incorporated in a steering device for an automobile.

[0042] [Outline of Steering Device] As shown in the overall configuration in FIG. 1, the steering device 1 is an electric power steering device of a column assist type.

[0043] The steering device 1 includes a steering wheel 2, a steering shaft 3, a steering column 4, two universal joints 5a and 5b, an intermediate shaft 6, a steering gear unit 7, a pair of tie rods 8, and an electric assist device 9.

[0044] The steering shaft 3 is rotatably supported inside a steering column 4 supported by the vehicle body. A steering wheel 2 operated by the driver is fixed to the rear end of the steering shaft 3. The front end of the steering shaft 3 is inserted inside a gear housing 10 fixed to the steering column 4 and is connected to an output shaft 12 via a torsion bar 11.

[0045] The front-rear direction refers to the front-rear direction of the vehicle to which the steering device 1 is assembled.

[0046] The rotation of the output shaft 12 is transmitted to a pinion shaft 13 constituting a steering gear unit 7 via two universal joints 5a, 5b and an intermediate shaft 6. The rotation of the pinion shaft 13 is converted into a linear motion of a rack shaft meshing with the pinion shaft 13, and pushes and pulls a pair of tie rods 8. Thereby, a steering angle corresponding to the operation amount of the steering wheel 2 is imparted to the steered wheels.

[0047] As shown in FIG. 2, the electric assist device 9 includes a torque sensor 14, an ECU (not shown), an electric motor 15, and a worm reduction gear 16.

[0048] The torque sensor 14 is disposed around the output shaft 12 and detects the relative torsional direction and torsional amount of the output shaft 12 with respect to the steering shaft 3. The ECU determines auxiliary torque based on the detection signal of the torque sensor 14 and the vehicle speed signal measured by a vehicle speed sensor (not shown). The electric motor 15 is fixed to the gear housing 10, and the energization direction and energization amount are controlled by the ECU. The worm reduction gear 16 reduces the rotational force of the electric motor 15 and transmits it to the output shaft 12. The electric assist device 9 applies auxiliary torque to the output shaft 12 and reduces the steering force required for the driver to operate the steering wheel 2.

[0049] The universal joint 5a connects the respective ends of the intermediate shaft 6 and the output shaft 12, which are two non-coaxial rotating shafts, in a torque-transmittable manner.

[0050] The universal joint 5b connects the respective ends of the intermediate shaft 6 and the pinion shaft 13, which are two non-coaxial rotating shafts, in a torque-transmittable manner.

[0051] As shown in FIG. 3, the universal joint 5b is composed of a first yoke 17 corresponding to a clamp device fixed to the end of the pinion shaft 13, a second yoke 18 fixed to the end of the intermediate shaft 6, and a cross shaft 19.

[0052] Note that the rotating shaft according to one aspect of the present disclosure can be applied to the intermediate shaft 6 instead of the pinion shaft 13, or can be applied to both the pinion shaft 13 and the intermediate shaft 6. Additionally or alternatively, the rotating shaft according to one aspect of the present disclosure can also be applied to at least one of the intermediate shaft 6 and the output shaft 12 that are torque-transmittably connected by the universal joint 5a. In these cases as well, since the same configuration as that of the pinion shaft is adopted, the description thereof is omitted in this specification.

[0053] Hereinafter, the pinion shaft 13 and the coupling structure between the pinion shaft 13 and the first yoke 17 will be described with reference to FIGS. 4 to 15.

[0054] [Structure of Pinion Shaft] The pinion shaft 13 is made of metal and has a substantially cylindrical shape. The pinion shaft 13 rotates around the central axis O 13 during use.

[0055] The pinion shaft 13 has a connection portion 20 inserted into the first yoke 17 at one end in the axial direction, and has pinion teeth (not shown) meshing with the rack teeth provided on the rack shaft on the outer peripheral surface of the other end in the axial direction.

[0056] The connection portion 20 is inserted into the first yoke 17 and fixed to the first yoke 17 so as not to be relatively rotatable.

[0057] The connecting portion 20 has a non-cylindrical shape. The cross-sectional shape of the connecting portion 20 with respect to a virtual plane orthogonal to the central axis O of the pinion shaft 13 is non-circular. In this example, the connecting portion 20 has a substantially rounded triangular prism shape and has a cross-sectional shape of a substantially rounded triangle. 13 The axial dimension of the connecting portion 20 is shorter than the axial dimension of a base portion 24, which will be described later, that constitutes the first yoke 17.

[0058] The connecting portion 20 has, on its outer peripheral surface, three male serration portions 21a to 21c and three tooth non-forming portions 22a to 22c. In other words, the outer peripheral surface of the connecting portion 20 is composed of three male serration portions 21a to 21c and three tooth non-forming portions 22a to 22c. On the outer peripheral surface of the connecting portion 20, the male serration portions 21a to 21c and the tooth non-forming portions 22a to 22c are alternately arranged in the circumferential direction.

[0059] The male serration portions 21a to 21c are arranged at three locations on the outer peripheral surface of the connecting portion 20 at substantially equal intervals in the circumferential direction. For this reason, the male serration portions 21a to 21c are arranged at approximately 120-degree intervals.

[0060] Each of the male serration portions 21a to 21c is provided with male serration teeth 23. The male serration portions 21a to 21c are composed of a plurality of male serration teeth 23.

[0061] The number of teeth of the male serration teeth 23 may be different for each of the male serration portions 21a to 21c, but the pitch, tooth width, tip circle diameter, and root circle diameter of the male serration teeth 23 are the same for each of the male serration portions 21a to 21c.

[0062] The male serration teeth 23 are serration-engaged with female serration teeth 30, which will be described later, provided on the first yoke 17 when the connecting portion 20 is inserted into the first yoke 17.

[0063]

[0064] ​The central axis O of the pinion shaft 13 13 The central angles α1 to α3 of the male serration portions 21a to 21c centered on 13 are about 30 degrees to 60 degrees. In this example, the central angle α1 of the male serration portion 21a is approximately 45 degrees, and the central angles α2 and α3 of the male serration portions 21b and 21c are approximately 50 degrees.

[0065] Chamfers (C chamfers) are formed at one axial end of the male serration portions 21a to 21c.

[0066] The tooth non-forming portions 22a to 22c are not provided with male serration teeth 23.

[0067] The tooth non-forming portions 22a to 22c are provided between the circumferentially adjacent male serration portions 21a to 21c on the outer peripheral surface of the connecting portion 20. Specifically, the tooth non-forming portion 22a is provided between the circumferentially adjacent male serration portions 21a and 21b. The tooth non-forming portion 22b is provided between the circumferentially adjacent male serration portions 21b and 21c. The tooth non-forming portion 22c is provided between the circumferentially adjacent male serration portions 21a and 21c.

[0068] Therefore, when the pinion shaft 13 is viewed from one axial end, on the outer peripheral surface of the connecting portion 20, in the counterclockwise direction, the male serration portion 21a → the tooth non-forming portion 22a → the male serration portion 21b → the tooth non-forming portion 22b → the male serration portion 21c → the tooth non-forming portion 22c are arranged in this order.

[0069] The tooth non-forming portions 22a to 22c are entirely located radially inside the root circle S of the male serration teeth 23 23 than that.

[0070] The tooth non-forming portions 22a to 22c do not engage in serration with the female serration teeth 30 provided on the first yoke 17 when the connecting portion 20 is inserted into the first yoke 17.

[0071] In this example, the tooth non-forming portions 22a to 22c are constituted by planes. The tooth non-forming portions 22a to 22c are arranged parallel to the central axis O of the pinion shaft 13. 13

[0072] However, when implementing the present disclosure, the tooth non-forming portion is not limited to a plane, and may be constituted by a concave curved surface or the like, or may be constituted by other surfaces, as long as it is located radially inside the root circle of the male serration teeth. Further, the tooth non-forming portion constituted by a plane may be inclined with respect to the central axis of the pinion shaft.

[0073] The distance L1 from the central axis O of the pinion shaft 13 to the tooth non-forming portions 22a to 22c may be different for each of the tooth non-forming portions 22a to 22c, but in this example, they are the same among the tooth non-forming portions 22a to 22c. 13

[0074] The central angles β1 to β3 of the tooth non-forming portions 22a to 22c centered on the central axis O of the pinion shaft 13 are about 60 degrees to 90 degrees. In this example, the central angles β1 and β3 of the tooth non-forming portions 22a and 22c are approximately 75 degrees, and the central angle β2 of the tooth non-forming portion 22b is approximately 65 degrees. 13

[0075] Therefore, in this example, the central angles α1, α2, and α3 of the male serration portions 21a to 21c are smaller than the central angles β1, β2, and β3 of the tooth non-forming portions 22a to 22c.

[0076] The connecting portion 20 of the pinion shaft 13 in this example as described above has an overall substantially rounded triangular prism shape, and male serration portions 21a to 21c are provided at portions corresponding to three sides (corners, partial cylindrical surfaces) of the outer peripheral surface, and planar tooth non-forming portions 22a to 22c are provided at portions corresponding to three side surfaces of the outer peripheral surface.

[0077] ​​​The connecting portion 20 of the pinion shaft 13 can be formed, for example, by pressing. That is, the male serration portions 21a to 21c and the tooth non-formation portions 22a to 22c can be formed by pressing. However, the male serration portions 21a to 21c and / or the tooth non-formation portions 22a to 22c can also be formed by cutting other than pressing. The tooth non-formation portions 22a to 22c can be formed, for example, by milling.

[0078] [Structure of the yoke] As shown in FIGS. 10 to 15, the first yoke 17 is a so-called closed slit type yoke and includes a base portion 24 having a substantially cylindrical shape and a pair of flange portions 25a and 25b.

[0079] The base portion 24 has a slit 26 extending in the axial direction at one location in the circumferential direction and is configured to be able to reduce the diameter. The pair of flange portions 25a and 25b are disposed on both sides of the slit 26 with respect to the circumferential direction of the base portion 24. The first yoke 17 is fixed to the pinion shaft 13 by screwing and further tightening a bolt 28 (see FIG. 3) inserted through a mounting hole 27a provided in one flange portion 25a into a mounting hole 27b provided in the other flange portion 25b, thereby tightening the base portion 24 to the connecting portion 20 of the pinion shaft 13.

[0080] Regarding the first yoke 17, unless otherwise specified, the axial direction, circumferential direction, and radial direction refer to the axial direction, circumferential direction, and radial direction of the base portion 24 and coincide with the axial direction, circumferential direction, and radial direction of the pinion shaft 13. One side in the axial direction refers to the right side in FIGS. 3, 10 to 12, and the other side in the axial direction refers to the left side in FIGS. 3, 10 to 12. Also, the front-back direction in FIG. 10, the up-down direction in FIGS. 11 and 12, and the left-right direction in FIGS. 13 to 15, which are directions orthogonal to the axial direction of the base portion 24, are referred to as the first direction. Note that the first direction coincides with the central axis direction of the mounting holes 27a and 27b. The up-down direction in FIG. 10, the front-back direction in FIGS. 11 and 12, and the up-down direction in FIGS. 13 to 15, which are directions orthogonal to each of the axial direction and the first direction of the base portion 24, are referred to as the second direction.

[0081] A slit refers to an elongated gap with a width dimension smaller than its length dimension.

[0082] The first yoke 17 is made of a metal material and is manufactured by, for example, forging and cutting processes.

[0083] The base 24 has a substantially cylindrical shape.

[0084] The base 24 has an insertion hole 29 and a slit 26.

[0085] The insertion hole 29 opens at least on the end face on the other side in the axial direction of the base 24 and extends in the axial direction. In this example, the insertion hole 29 penetrates the base 24 in the axial direction. Specifically, the insertion hole 29 penetrates the central portion in the radial direction of the base 24 in the axial direction. That is, the central axis O of the insertion hole 29 29 coincides with the central axis of the base 24. A connection portion 20 provided at one end in the axial direction of the pinion shaft 13 is inserted into the insertion hole 29. The insertion hole is not limited to a through hole penetrating the base in the axial direction, and can also be configured as a bottomed hole that opens only on the end face on the other side in the axial direction of the base.

[0086] The insertion hole 29 has a substantially gear-shaped cross-sectional shape. More specifically, the insertion hole 29 is constituted by a serration hole in which female serration teeth 30 are arranged in the circumferential direction on the inner peripheral surface of the base 24. The female serration teeth 30 engage non-rotatably with male serration teeth 23 provided on the outer peripheral surface of the connection portion 20 of the pinion shaft 13.

[0087] The base 24 has a toothless portion 31 where the female serration teeth 30 are not formed in a part of the inner peripheral surface in the circumferential direction. The toothless portion 31 is provided in a range that straddles the slit 26 in the circumferential direction on the inner peripheral surface of the base 24. The toothless portion 31 is configured in a partial cylindrical surface shape centered on the central axis O of the insertion hole 29. The inner diameter of the toothless portion 31 has the same size as the root circle diameter of the female serration teeth 30. 29 is centered.

[0088] The central axis O of the insertion hole 29 29The central angle of the toothless portion 31 centered on [the relevant element] is not particularly limited. In this example, the central axis O of the insertion hole 29 29 The central angle of the toothless portion 31 centered on [the relevant element] is approximately 80 degrees.

[0089] The female serration teeth 30 and the toothless portion 31 are formed in a range extending from one end in the axial direction to the other end in the axial direction of the inner peripheral surface of the base portion 24.

[0090] The female serration teeth 30 and the toothless portion 31 are formed, for example, by broaching using a broaching tool.

[0091] The slit 26 is arranged at one location in the circumferential direction of the base portion 24 and extends in the axial direction. The length direction of the slit 26 coincides with the axial direction, the width direction of the slit 26 coincides with the first direction, and the depth direction of the slit 26 coincides with the second direction.

[0092] The slit 26 extends linearly in the axial direction. The central axis O of the slit 26 26 is arranged substantially parallel to the central axis O of the insertion hole 29 29

[0093] The slit 26 opens to the outer peripheral surface and the inner peripheral surface of the base portion 24.

[0094] The slit 26 is formed in a range extending from the other end in the axial direction of the base portion 24 to a part on one side in the axial direction.

[0095] One end in the axial direction of the slit 26 is a closed end 32 closed in the axial direction, and the other end in the axial direction of the slit 26 is an open end 33 open in the axial direction. That is, the slit 26 does not open to the end face on one side in the axial direction of the base portion 24, but opens to the end face on the other side in the axial direction of the base portion 24. The closed end 32 is located in a part on one side in the axial direction of the base portion 24.

[0096] The slit 26 has a rectangular opening shape that is long in the axial direction when viewed from the second direction.

[0097] ​ The width dimension of the slit 26 is constant over the entire length of the slit 26 in the state before tightening the bolt 28. However, the width dimension of the slit can also be varied according to the axial position of the slit.

[0098] The closed end 32 of the slit 26 includes the central axis O of the insertion hole 29 29 and is configured by a concave cylindrical surface having an arcuate cross-sectional shape with respect to a cross-section orthogonal to the first direction. In other words, the closed end 32 is inclined in the direction toward one side in the axial direction as it goes toward the radially outer side, and is configured by a partial cylindrical surface facing the radially outer side.

[0099] However, when implementing the present disclosure, the closed end of the slit can also be configured by a plane orthogonal to the central axis of the insertion hole, or can be configured by a partial cylindrical surface having a substantially semi-circular arc shape when viewed from the second direction.

[0100] The slit 26 is formed, for example, by cutting using a cutter which is a rotary cutting tool.

[0101] However, when implementing the present disclosure, the slit may be formed by other methods other than cutting.

[0102] The pair of flange portions 25a and 25b are arranged on both sides of the slit 26 in the circumferential direction.

[0103] The pair of flange portions 25a and 25b are provided on the outer peripheral surface of the end portion on the other axial side of the base portion 24. The pair of flange portions 25a and 25b project in the second direction respectively from the portions of the outer peripheral surface of the base portion 24 that are located on both sides of the slit 26 in the circumferential direction. The pair of flange portions 25a and 25b each have a plate shape.

[0104] In this example, the pair of flange portions 25a and 25b have a substantially semi-circular side surface shape when viewed from the first direction.

[0105] In this example, a pair of flange portions 25a and 25b are integral with the base portion 24. Specifically, the proximal ends of the pair of flange portions 25a and 25b are continuous with the outer peripheral surface of the end portion on the other axial side of the base portion 24.

[0106] The pair of flange portions 25a and 25b are spaced apart in the first direction and are arranged substantially parallel to each other. A gap 34 is provided between the inner surfaces of the pair of flange portions 25a and 25b with respect to the first direction. The gap 34 is continuous with the slit 26 in the second direction. The gap 34 has the same size as the width dimension of the slit 26 in a state before the bolt 28 is tightened. The gap 34 can be formed by cutting simultaneously with the slit 26 using a cutter which is a rotary cutting tool.

[0107] The pair of flange portions 25a and 25b have mounting holes 27a and 27b coaxially. The central axis O 27 of the mounting holes 27a and 27b faces the first direction. The central axis O 27 of the mounting holes 27a and 27b is arranged in a twisted position with respect to the central axis O 29 of the insertion hole 29.

[0108] In this example, one of the pair of mounting holes 27a and 27b, i.e., the mounting hole 27a, is a bolt insertion hole which is a cylindrical hole, and the other mounting hole 27b of the pair of mounting holes 27a and 27b is a threaded hole.

[0109] However, when implementing the present disclosure, the pair of mounting holes can also be cylindrical holes. In this case, by screwing a nut onto the tip of the bolt inserted through the pair of mounting holes, the diameter of the base portion is reduced.

[0110] The first yoke 17 further includes a connecting portion 35 for connectably transmitting torque to another member.

[0111] In this example, the connecting portion 35 is constituted by a pair of arm portions 36a and 36b. The pair of arm portions 36a and 36b extend in the axial direction respectively and are arranged spaced apart from each other.

[0112] The pair of arm portions 36a and 36b are each configured in a substantially plate shape. The pair of arm portions 36a and 36b are arranged adjacent to one axial side of the base portion 24. The proximal ends of the pair of arm portions 36a and 36b are connected to two positions on the one axial side end of the base portion 24 that are on the opposite side in the radial direction.

[0113] In the illustrated example, the pair of arm portions 36a and 36b are arranged spaced apart in the second direction. In other words, the pair of arm portions 36a and 36b are arranged at positions where the phase with respect to the circumferential direction is shifted by 90 degrees with respect to the pair of flange portions 25a and 25b.

[0114] However, when implementing the present disclosure, the pair of arm portions may be arranged spaced apart in the first direction or spaced apart in other directions.

[0115] Among the pair of arm portions 36a and 36b, the phase of one arm portion 36a with respect to the circumferential direction coincides with the phase of the slit 26 with respect to the circumferential direction.

[0116] In this example, the pair of arm portions 36a and 36b are integrally formed with the base portion 24.

[0117] The pair of arm portions 36a and 36b each have a through hole 37 which is a through hole arranged coaxially. In the through hole 37, the shaft portion constituting the cross shaft 19 is rotatably supported via a bearing cup.

[0118] To fix the first yoke 17 to the connecting portion 20 of the pinion shaft 13, the central axis O of the pinion shaft 13 13 and the central axis O of the insertion hole 29 29 are made coaxial, and the connecting portion 20 is inserted into the insertion hole 29.

[0119] In this example, among the three male serration portions 21a to 21c provided on the outer peripheral surface of the connecting portion 20, one male serration portion 21a (21b, 21c) is directed toward the radially opposite side of the slit 26, and the remaining two male serration portions 21b and 21c (21a) are positioned on both circumferential sides of the toothless portion 31, and the connecting portion 20 is inserted into the insertion hole 29. In other words, the toothless portion 22b provided on the outer peripheral surface of the connecting portion 20 is directed toward the slit 26 side, and the toothless portion 22b and the central axes O of the mounting holes 27a and 27b 27 are arranged in parallel, and the connecting portion 20 is inserted into the insertion hole 29.

[0120] Then, the male serration teeth 23 provided on the male serration portions 21a to 21c are engaged in serration with the female serration teeth 30. The toothless portions 22a to 22c are not engaged in serration with the female serration teeth 30.

[0121] Also, a bolt 28 inserted through the mounting hole 27a provided in one flange portion 25a is screwed into the mounting hole 27b provided in the other flange portion 25b. Then, by further tightening the bolt 28, the width dimensions of the slit 26 and the gap 34 are reduced, the diameter of the base portion 24 is reduced, and the end portion of the pinion shaft 13 is tightened by the base portion 24.

[0122] Thereby, the first yoke 17 is fixed to the connecting portion 20 of the pinion shaft 13. In this state, a gap 38 having a substantially arcuate cross-sectional shape is formed between the female serration teeth 30 and the toothless portion 22a facing each other in the radial direction, and between the female serration teeth 30 and the toothless portion 22c facing each other in the radial direction. The female serration teeth 30 and the toothless portions 22a and 22c facing each other in the radial direction do not engage in the circumferential direction even when the male serration teeth 23 and / or the female serration teeth 30 are damaged. A gap 39 having a substantially arcuate cross-sectional shape is also formed between the toothless portion 31 and the toothless portion 22b facing each other in the radial direction. The intermediate portion of the bolt 28 and the toothless portion 22b are in close proximity to each other.

[0123] According to the pinion shaft 13 in this example, the tightening force by the first yoke 17 can be increased.

[0124] The connection part 20 of the pinion shaft 13 in this example is arranged at three positions on the outer peripheral surface, which are spaced at substantially equal intervals in the circumferential direction, and has male serration parts 21a to 21c provided with male serration teeth 23, and is arranged between the male serration parts 21a to 21c adjacent to each other in the circumferential direction, and has tooth non-formation parts 22a to 22c not provided with male serration teeth 23. Among these, the tooth non-formation parts 22a to 22c are located radially inside the root circle S of the male serration teeth 23. 23 and are located radially inside the root circle S of the male serration teeth 23.

[0125] Therefore, when the connection part 20 of the pinion shaft 13 is inserted into the inside of the base part 24 constituting the first yoke 17 and the base part 24 is reduced in diameter by tightening the bolt 28, a gap 38 can be formed between the female serration teeth 30 and the tooth non-formation parts 22a, 22c (22b) facing each other in the radial direction. Therefore, it is possible to suppress the surface pressure between the female serration teeth 30 and the male serration teeth 23 from becoming excessively high partially, and reduce the axial force loss of the bolt 28, so that the tightening force by the first yoke 17 can be increased.

[0126] Thus, according to the pinion shaft 13 in this example, even without performing special processing on the inner peripheral surface of the base part 24 constituting the first yoke 17, by only performing processing on the outer peripheral surface of the connection part 20 of the pinion shaft 13, which has a simpler structure than the first yoke 17, the tightening force by the first yoke 17 can be increased. Therefore, the processing man-hours and processing costs can be reduced. Also, it is not necessary to reduce the strength of the base part 24.

[0127] In particular, when inserting the connecting portion 20 of the pinion shaft 13 inside the base portion 24 that constitutes the first yoke 17, if one of the three male serration portions 21a to 21c, i.e., male serration portion 21a (21b, 21c), is inserted toward the radially opposite side of the slit 26, the base portion 24 can be efficiently deformed starting from the radially opposite side portion of the slit 26. Also, the two tooth non-forming portions 22a, 22c are arranged on both sides with a virtual plane including the central axis O 29 of the insertion hole 29 26 and the central axis O of the slit 26

[0128] sandwiched therebetween, so that each male serration tooth 23 and the female serration tooth 30 that constitute the male serration portions 21a to 21c can be strongly meshed. For this reason, high torque can be transmitted between the pinion shaft 13 and the first yoke 17.

[0129] Also, since the two male serration portions 21b, 21c are stretched in the first direction inside the base portion 24, the bending rigidity of the first yoke 17 in the first direction is improved.

[0130] Furthermore, in this example, when the bolt 28 is tightened, a gap 39 is also formed between the tooth non-forming portion 22b provided on the outer peripheral surface of the connecting portion 20 and the tooth missing portion 31 provided on the inner peripheral surface of the base portion 24. Therefore, the axial force loss when the bolt 28 is tightened can be reduced, and from this aspect as well, the tightening force by the first yoke 17 can be increased.

[0130] The pinion shaft 13 of this example can reduce the axial force loss when the bolt 28 is tightened and can sufficiently secure the tightening force by the base portion 24 of the first yoke 17. Therefore, the pinion shaft 13 and the first yoke 17 of this example, even when incorporated in a column assist type steering device 1 where not only the torque by the driver operating the steering wheel 2 but also the high torque assist torque by the electric assist device 9 is transmitted, the fine sliding of the pinion shaft 13 with respect to the base portion 24 is suppressed. For this reason, damage such as fretting wear and fretting corrosion can be suppressed from occurring on the male serration teeth 23 and / or the female serration teeth 30.

[0131] Since the outer peripheral surface of the connecting portion 20 is provided with male serration portions 21a to 21c at three positions spaced apart at substantially equal intervals in the circumferential direction, a force can be applied to the connecting portion 20 substantially evenly in the circumferential direction.

[0132] In this example, since the tooth non-forming portions 22a to 22c of the connecting portion 20 are formed by planes, a gap 38 having a substantially arcuate cross-sectional shape can be formed between the female serration teeth 30 and the tooth non-forming portions 22a to 22c. Therefore, it is possible to effectively prevent the female serration teeth 30 from coming into contact with the tooth non-forming portions 22a to 22c. Further, since the tooth non-forming portions 22a to 22c can be easily machined by press working or cutting, etc., the processing cost can be reduced.

[0133] Furthermore, by forming the tooth non-forming portions 22a to 22c constituting the connecting portion 20 by planes, it is not necessary to interfere between the tooth non-forming portion 22b (22a, 22c) and the outer peripheral surface of the bolt 28. Therefore, by adjusting the insertion amount of the connecting portion 20 into the insertion hole 29 of the first yoke 17, the fixing position between the first yoke 17 and the connecting portion 20 can be adjusted. Therefore, the structure of the pinion shaft 13 in this example can be preferably applied to a rigid type intermediate shaft that cannot expand and contract, and a collapsible type intermediate shaft that can contract when a large force is applied.

[0134] [Second Example] A second example of the embodiment of the present disclosure will be described with reference to FIGS. 16 to 20.

[0135] In the connecting portion 20a of the pinion shaft 13a in this example, an engagement groove 40 is provided in one of the three tooth non-forming portions 22a to 22c, i.e., the tooth non-forming portion 22b.

[0136] In this example, the ends of the engagement groove 40 are also formed in the axial intermediate portions of the male serration portions 21b and 21c arranged on both sides in the circumferential direction of the tooth non-forming portion 22b.

[0137] The engagement groove 40 extends in a direction orthogonal to the central axis O of the pinion shaft 13a 13 and extends in a direction orthogonal to the central axis O of the pinion shaft 13a.

[0138] The central axis O of the pinion shaft 13a 13 The cross-sectional shape of the engagement groove 40 with respect to the virtual plane including the central axis O of the pinion shaft 13a and orthogonal to the tooth non-forming portion 22b is a substantially U-shape or a single arc shape.

[0139] However, the cross-sectional shape of the engagement groove is not limited to a substantially U-shape or a single arc shape, and other shapes can be adopted as long as they can be axially engaged with the bolt 28.

[0140] In this example, when inserting the connection portion 20a of the pinion shaft 13a into the insertion hole 29 of the first yoke 17, the phases of the tooth non-forming portion 22b provided with the engagement groove 40 and the slit 26 are made to coincide. Thereby, when the connection portion 20a of the pinion shaft 13a is inserted into the insertion hole 29 of the first yoke 17, the engagement groove 40 and the pair of mounting holes 27a, 27b can be arranged coaxially. Therefore, by engaging the middle portion of the bolt 28 with the engagement groove 40, axial retention of the pinion shaft 13a with respect to the first yoke 17 can be achieved.

[0141] Regarding other configurations and effects of the second example, they are the same as those of the first example.

[0142] [Third Example] The third example of the embodiment of the present disclosure will be described with reference to FIGS. 21 to 23.

[0143] The connection portion 20b of the pinion shaft 13b in this example is provided with a tooth dropout portion 41 in addition to the male serration teeth 23 in one of the three male serration portions 21a to 21c, i.e., the male serration portion 21a. That is, the male serration portion 21a is composed of a plurality of male serration teeth 23 and the tooth dropout portion 41.

[0144] The tooth dropout portion 41 is provided at one circumferential location (central portion) of the male serration portion 21a, and is formed by notching (removing) the male serration teeth 23 provided at that portion.

[0145] In this example, the base 24a of the first yoke 17a has a greater tooth thickness than the female serration teeth 30 provided on the inner peripheral surface at the portion of the inner peripheral surface radially opposite to the slit 26, and has thick teeth 42 that can be engaged in the circumferential direction with the toothless portion 41 of the connecting portion 20b.

[0146] In this example, when the connecting portion 20b is inserted into the insertion hole 29a of the base 24a, the toothless portion 41 is engaged with the thick teeth 42, so that the phase of the pinion shaft 13b and the first yoke 17a can be determined.

[0147] As a modification of this example, as the pinion shaft, one having thick teeth with a greater tooth thickness than the male serration teeth is used for one of the three male serration portions provided at the connecting portion, and as the first yoke, one having a toothless portion that can be engaged with the thick teeth in the circumferential direction is used at any one location on the inner peripheral surface of the base.

[0148] Regarding other configurations and operational effects of the third example, they are the same as those of the first example.

[0149] [Fourth Example] The fourth example of the embodiment of the present disclosure will be described with reference to FIGS. 24 to 27.

[0150] In this example, only the structure of the first yoke 17b is changed from the structure of the second example.

[0151] In this example, the base 24b constituting the first yoke 17b has three female serration portions 43a to 43c, one toothless portion 31, and two toothless engagement portions 44a and 44b on the inner peripheral surface.

[0152] The female serration portions 43a to 43c are arranged at three locations on the inner peripheral surface of the base 24b at substantially equal intervals in the circumferential direction. Therefore, the female serration portions 43a to 43c are arranged at approximately 120-degree intervals.

[0153] Each of the female serration portions 43a to 43c is provided with female serration teeth 30. The female serration portions 43a to 43c are composed of a plurality of female serration teeth 30.

[0154] The number of teeth of the female serration teeth 30 may be different for each of the female serration portions 43a to 43c, but the pitch, tooth width, tip circle diameter, and root circle diameter of the female serration teeth 30 are the same among the female serration portions 43a to 43c.

[0155] When the connection portion 20a of the pinion shaft 13a is inserted inside the base portion 24b of the first yoke 17b, the female serration teeth 30 provided in the female serration portions 43a to 43c are serration-engaged with the male serration teeth 23 provided in the male serration portions 21a to 21c, respectively.

[0156] The toothless portion 31 is provided in a range of the inner peripheral surface of the base portion 24b that straddles the slit 26 in the circumferential direction. The toothless portion 31 is configured in a partial cylindrical surface shape centered on the central axis O 29 of the insertion hole 29b. The inner diameter of the toothless portion 31 has the same size as the root circle diameter of the female serration teeth 30.

[0157] The toothless engagement portions 44a and 44b are provided between the female serration portions 43a to 43c adjacent to each other in the circumferential direction on the inner peripheral surface of the base portion 24b. Specifically, the toothless engagement portion 44a is provided between the female serration portions 43a and 43b adjacent to each other in the circumferential direction. The toothless engagement portion 44b is provided between the female serration portions 43a and 43c adjacent to each other in the circumferential direction. Note that a toothless portion 31 is provided between the female serration portions 43b and 43c adjacent to each other in the circumferential direction.

[0158] Therefore, when the base portion 24b of the first yoke 17b is viewed from one end in the axial direction, on the inner peripheral surface of the base portion 24b, in the counterclockwise direction, the female serration portion 43a → the toothless engagement portion 44a → the female serration portion 43b → the toothless portion 31 → the female serration portion 43c → the toothless engagement portion 44b are arranged in this order.

[0159] The toothless engagement portions 44a and 44b project radially inward beyond the tip circle S of the female serration teeth 30 as a whole. 30 They project radially inward beyond the tip circle S of the female serration teeth 30 as a whole.

[0160] In this example, the toothless engagement portions 44a and 44b are constituted by planes. The toothless engagement portions 44a and 44b are arranged parallel to the central axis O of the insertion hole 29b. 29 They are arranged parallel to the central axis O of the insertion hole 29b.

[0161] However, when implementing the present disclosure, as long as the toothless engagement portion is located radially inward of the tip circle of the female serration teeth, it is not limited to a plane, and may be constituted by a convex curved surface or the like, or may be constituted by other surfaces. Further, the toothless engagement portion constituted by a plane may be inclined with respect to the central axis of the insertion hole.

[0162] The distance L2 from the central axis O of the insertion hole 29b to the toothless engagement portions 44a and 44b may be different for each of the toothless engagement portions 44a and 44b, but in this example, it is the same between the two toothless engagement portions 44a and 44b. The distance L2 from the central axis O of the insertion hole 29b to the toothless engagement portions 44a and 44b is slightly larger than the distance L1 from the central axis O of the pinion shaft 13a to the tooth non-formation portions 22a to 22c (L2 > L1). 29 The distance L2 from the central axis O of the insertion hole 29b to the toothless engagement portions 44a and 44b may be different for each of the toothless engagement portions 44a and 44b, but in this example, it is the same between the two toothless engagement portions 44a and 44b. The distance L2 from the central axis O of the insertion hole 29b to the toothless engagement portions 44a and 44b is slightly larger than the distance L1 from the central axis O of the pinion shaft 13a to the tooth non-formation portions 22a to 22c (L2 > L1). 29 The distance L2 from the central axis O of the insertion hole 29b to the toothless engagement portions 44a and 44b is slightly larger than the distance L1 from the central axis O of the pinion shaft 13a to the tooth non-formation portions 22a to 22c (L2 > L1). 13 The distance L2 from the central axis O of the insertion hole 29b to the toothless engagement portions 44a and 44b is slightly larger than the distance L1 from the central axis O of the pinion shaft 13a to the tooth non-formation portions 22a to 22c (L2 > L1).

[0163] Also in the case of this example, to fix the first yoke 17b to the connection portion 20a of the pinion shaft 13a, among the three male serration portions 21a to 21c provided on the outer peripheral surface of the connection portion 20a, one male serration portion 21a (21b, 21c) is directed to the radially opposite side of the slit 26, and the remaining two male serration portions 21b and 21c (21a) are positioned on both circumferential sides of the toothless portion 31, and then the connection portion 20a is inserted into the insertion hole 29b.

[0164] Then, the male serration teeth 23 provided on the male serration portions 21a to 21c are engaged in serration with the female serration teeth 30 provided on the female serration portions 43a to 43c. Further, the tooth non-forming portions 22a and 22c provided on the outer peripheral surface of the connecting portion 20a and the tooth missing engaging portions 44a and 44b provided on the inner peripheral surface of the base portion 24b are opposed to each other in the radial direction with a minute gap 45 therebetween. The tooth non-forming portions 22a and 22c and the tooth missing engaging portions 44a and 44b do not engage with each other in the circumferential direction under normal conditions, but can engage with each other in the circumferential direction when the male serration teeth 23 and / or the female serration teeth 30 are damaged.

[0165] In this example, when the male serration teeth 23 and / or the female serration teeth 30 are damaged due to an accident or the like, the tooth non-forming portions 22a and 22c and the tooth missing engaging portions 44a and 44b engage with each other in the circumferential direction, so that torque can be transmitted between the pinion shaft 13a and the first yoke 17b.

[0166] Based on the minute gap 45 provided between the tooth non-forming portions 22a and 22c and the tooth missing engaging portions 44a and 44b, play occurs when the rotation direction of the pinion shaft 13a is switched, so that a driver operating the steering wheel can be notified that an abnormality has occurred in the steering device 1. Further, even when the male serration teeth 23 and / or the female serration teeth 30 are damaged, it is possible to prevent the torque transmission between the pinion shaft 13a and the first yoke 17b from being immediately disabled, so that the vehicle can run by itself and be carried into a repair shop or the like.

[0167] Regarding other configurations and operational effects of the fourth example, they are the same as those of the first example and the second example.

[0168] As described above, the first to fourth examples of the embodiments of the present disclosure have been described. However, the structures of the first to fourth examples can be implemented in appropriate combinations as long as no contradiction occurs.

Explanation of Reference Numerals

[0169] 1 Steering device 2 Steering wheel 3 Steering shaft 4 Steering column 5a, 5b Universal joint 6 Intermediate shaft 7 Steering gear unit 8 Tie rod 9 Electric assist device 10 Gear housing 11 Torsion bar 12 Output shaft 13, 13a, 13b Pinion shaft 14 Torque sensor 15 Electric motor 16 Worm reducer 17, 17a, 17b First yoke 18 Second yoke 19 Cross shaft 20, 20a, 20b Connection part 21a~21c Male serration part 22a~22c Tooth non-forming part 23 Male serration teeth 24, 24a, 24b Base part 25a, 25b Flange part 26 Slit 27a, 27b Mounting hole 28 Bolt 29, 29a, 29b Insertion hole 30 Female serration teeth 31 Tooth missing part 32 Closed end 33 Open end 34 Gap 35 Connecting part 36a, 36b Arm part 37 Through hole 38 Gap 39 Gap 40 Engagement groove 41 Tooth skipping part 42 Thick tooth 43a~43c Female serration part 44a, 44b Tooth missing engagement part 45 Micro gap

Claims

1. The clamping device has a connecting portion that rotates around a central axis and is inserted into a clamping device at an axial end thereof. The connection portion has male serration portions disposed on the outer peripheral surface at three locations spaced at approximately equal intervals in the circumferential direction and provided with male serration teeth, and non-tooth forming portions disposed between adjacent male serration portions in the circumferential direction and not provided with male serration teeth, the non-tooth forming portion is located radially inward from a bottom circle of the male serration tooth, Rotation axis.

2. The rotating shaft according to claim 1 , wherein the non-toothed portion is formed of a flat surface.

3. The rotating shaft according to claim 2 , wherein the non-toothed portion is disposed parallel to the central axis.

4. 2. The rotating shaft according to claim 1, wherein one of the non-toothed portions has an engagement groove extending in a direction perpendicular to the central axis.

5. 2. The rotating shaft according to claim 1, wherein one of the male serration portions has, in addition to the male serration teeth, a toothless portion or a thick tooth having a tooth thickness greater than that of the male serration teeth.

6. 2. The rotating shaft according to claim 1, wherein a central angle of the male serration portion about the central axis is smaller than a central angle of the non-tooth forming portion about the central axis.

7. A rotating shaft according to any one of claims 1 to 6, a clamp device into which the connection portion is inserted, The clamp device has a substantially cylindrical base portion having female serration teeth on an inner peripheral surface thereof, and a pair of flange portions, the base portion has an insertion hole extending in an axial direction and a slit disposed at one location in a circumferential direction and extending in the axial direction, when the connecting portion is inserted into the insertion hole and the base portion is reduced in diameter, a gap is formed between the radially opposing female serration teeth and the non-tooth forming portion, and even if the male serration teeth and / or the female serration teeth are damaged, the radially opposing female serration teeth and the non-tooth forming portion do not engage with each other in the circumferential direction. The connecting structure between the rotating shaft and the clamping device.

8. A rotating shaft according to any one of claims 1 to 6, a clamp device into which the connection portion is inserted, The clamp device has a substantially cylindrical base portion having female serration portions on an inner peripheral surface, the female serration portions being arranged at three positions spaced at substantially equal intervals in the circumferential direction and having female serration teeth, and a toothless engagement portion being provided between adjacent female serration portions in the circumferential direction and not having the female serration teeth, and a pair of flange portions; the base portion has an insertion hole extending in an axial direction and a slit disposed at one location in a circumferential direction and extending in the axial direction, The missing tooth engagement portion protrudes radially inward from a tip circle of the female serration tooth, when the connecting portion is inserted into the insertion hole and the diameter of the base portion is reduced, the missing tooth engagement portion and the non-tooth formed portion face each other via a small gap, and when the male serration teeth and / or the female serration teeth are damaged, the missing tooth engagement portion and the non-tooth formed portion engage with each other in a circumferential direction. The connecting structure between the rotating shaft and the clamping device.

9. Equipped with an axis that rotates by operating the steering wheel, The shaft is a rotating shaft according to any one of claims 1 to 6. Steering gear.

Images