JP2006205833A - Telescopic shaft for vehicle steering, and method for fixing shaft end portion - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent generation of noises, such as rattles by making control of tolerance rough and positively applying a pre-load to a columnar body even while reducing the number of processes. <P>SOLUTION: A small-diameter portion 1a of which diameter is contracted is formed at an edge portion of a male shaft 1. A stopper plate 21 for regulating the movement of the columnar body 8 in an axial direction is provided at the small-diameter portion 1a. The stopper plate 21 consists of a plate spring 22, and a pair of first and second flat plates 23, 24 (namely washer, flat washer) for sandwiching the plate spring 22. Namely, the stopper plate 21 is engaged with the small-diameter portion 1a in the order of the first flat plate 23, the dish spring 22, and the second flat plate 24, and then rigidly fixed at the small-diameter portion 1a by caulking. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a telescopic shaft for vehicle steering and a shaft end fixing method in which a male shaft and a female shaft are fitted in a steering shaft of a vehicle so that the male shaft and the female shaft are mutually non-rotatable and slidable.

  The telescopic shaft of the steering mechanism portion of the automobile is required to absorb the axial displacement generated when the automobile travels and to transmit the displacement and vibration on the steering wheel. Further, in order to obtain an optimum position for the driver to drive the automobile, a function of moving the position of the steering wheel in the axial direction and adjusting the position is required.

  In any of these cases, the telescopic shaft is required to reduce the rattling noise, to reduce the rattling on the steering wheel, and to reduce the sliding resistance during the sliding operation in the axial direction. The

  For this reason, conventionally, the male shaft of the telescopic shaft is coated with a nylon film, and grease is applied to the sliding portion to absorb or alleviate metal noise, metal hitting sound, etc., and to reduce sliding resistance. The rotation direction play has been reduced.

  However, there is a case where wear of the nylon film progresses with the progress of use and the play in the rotational direction increases. In addition, under conditions where the engine room is exposed to high temperatures, the nylon membrane changes in volume, and the sliding resistance may increase remarkably or wear may be significantly accelerated, resulting in increased rotational play. .

  FIG. 4 is a longitudinal sectional view of the telescopic shaft for vehicle steering disclosed in Patent Document 1. As shown in FIG. A telescopic shaft 10 for steering a vehicle includes a male shaft 1 and a female shaft 2 that are slidably fitted to each other so as not to rotate.

  On the outer peripheral surface of the male shaft 1, three axial grooves 3 that are equally arranged at intervals of 120 degrees (phase) in the circumferential direction are formed to extend. Correspondingly, three axial grooves 5 that are equally arranged at intervals of 120 degrees (phase) in the circumferential direction are formed to extend on the inner peripheral surface of the female shaft 2.

  A leaf spring 9 is provided between the axial groove 3 of the male shaft 1 and the spherical body 7 so as to contact and preload the spherical body 7.

  On the outer peripheral surface of the male shaft 1, three axial grooves 4 that are equally arranged at intervals of 120 degrees (phase) in the circumferential direction extend. Correspondingly, three axial grooves 6 that are equally arranged at intervals of 120 degrees (phase) in the circumferential direction are formed to extend on the inner peripheral surface of the female shaft 2.

  A plurality of rigid cylindrical bodies 8 (sliding bodies) that slide between the axial grooves 4 of the male shaft 1 and the axial grooves 6 of the female shaft 2 when the two shafts 1 and 2 move relative to each other in the axial direction. , A needle roller) is interposed with a minute gap.

  In the telescopic shaft configured as described above, the spherical body 7 is interposed between the male shaft 1 and the female shaft 2, and the spherical body 7 is preloaded to the extent that the female shaft 2 is not rattled by the leaf spring 9. Therefore, the play between the male shaft 1 and the female shaft 2 can be reliably prevented, and when the male shaft 1 and the female shaft 2 move relative to each other in the axial direction, there is no stable play. It is possible to slide with the sliding load.

  A small diameter portion 1 a is formed at the end of the male shaft 1. The small-diameter portion 1a is provided with a stopper plate 11 that restricts the movement of the cylindrical body 8 in the axial direction.

  The stopper plate 11 includes an axial preload elastic body 12 and a pair of flat plates 13 and 14 that sandwich the axial preload elastic body 12.

That is, the stopper plate 11 is fitted to the small diameter portion 1a in the order of the flat plate 13, the axial preload elastic body 12, and the flat plate 14, and is firmly fixed to the small diameter portion 1a by caulking.

Thereby, the stopper plate 11 is being fixed to the axial direction. Further, the stopper plate 11 is configured such that the flat plate 13 is brought into contact with the cylindrical body 8 and the cylindrical body 8 can be appropriately preloaded by the axial preloading elastic body 12 so as not to move in the axial direction.
JP 2004-122938 A European Patent Application Publication No. EP1078843A1

  In the conventional example shown in FIG. 4, the flat plate 14 is fitted to the step portion 16 of the small diameter portion 1a, and the tip of the small diameter portion 1a is crimped.

  Between the distance from the end face 15 to the crimping receiver (L: see FIG. 4), a cylindrical body 8, a flat plate 13, an axial preload elastic body 12, and a number of components are provided. In order to use the position of the crimping receiver within the range of the available deflection amount of the axial preloading elastic body 12 (the range in which the preload that can fix the cylindrical body 8 firmly can be generated), the distance (L) is: There may be a need for a narrow tolerance range.

  Further, in Patent Document 2, a plurality of sets of torque transmission members (cylindrical bodies) are fitted between a plurality of sets of axial grooves formed on the outer peripheral surface of the male shaft and the inner peripheral surface of the female shaft. This prevents backlash between the male shaft and the female shaft during sliding, and the male shaft and the female shaft can slide in the axial direction with a stable sliding load without backlash. . Further, at the time of torque transmission, the male shaft and the female shaft can prevent backlash in the rotational direction and transmit torque in a highly rigid state. Furthermore, a resin-made adjusting member is provided between the plurality of cylindrical bodies arranged in parallel in the axial direction, and thereby configured to absorb gaps (play) between the plurality of cylindrical bodies. .

  However, in Patent Document 2, a gap between a plurality of cylindrical bodies is absorbed by a resin-made adjusting member provided between a plurality of cylindrical bodies arranged in parallel in the axial direction. There may be a gap between them, and as a result, an abnormal noise such as “knack” may occur.

  The present invention has been made in view of the circumstances as described above, and provides a preload to the cylindrical body with certainty while making the tolerance management rough (rough) and reducing the processing man-hours. An object of the present invention is to provide a vehicle steering telescopic shaft and a shaft end fixing method capable of preventing such abnormal noise.

  In this specification and abstract, rough (rough) means that tolerance management is necessary, but simple.

In order to achieve the above object, a telescopic shaft for vehicle steering according to claim 1 of the present invention is incorporated in a steering shaft of a vehicle, and is for vehicle steering in which a male shaft and a female shaft are fitted non-rotatably and slidably. In the telescopic axis,
A first flat plate, a disc spring, and a second flat plate are sequentially attached to the reduced diameter tip of the male shaft,
A caulking process is performed on the reduced diameter of the male shaft.

The telescopic shaft for vehicle steering according to claim 2 of the present invention, the telescopic shaft is
A preload torque transmission unit that transmits the steering torque while preloading between the two shafts when the steering torque is a predetermined value or less;
And a rigid torque transmission unit configured to transmit the steering torque between the two shafts when the steering torque exceeds a predetermined value by contact of the rigid bodies.

In the telescopic shaft for vehicle steering according to claim 3 of the present invention, the preload torque transmitting portion is
Between the outer circumferential surface of the male shaft and the inner circumferential surface of the female shaft, the first torque transmission member is interposed between the at least one row of axial grooves formed through the elastic body,
The rigid torque transmission part is
A second torque transmitting member is interposed between at least one other groove direction formed on the outer peripheral surface of the male shaft and the inner peripheral surface of the female shaft, respectively.

The telescopic shaft for vehicle steering according to claim 4 of the present invention is such that the first torque transmission member is a rolling element that rolls in the axial relative movement of the two shafts.
The second torque transmission member is a sliding body that slides and slides when the both wheels move in the axial direction relative to each other.

The shaft end portion fixing method according to claim 5 of the present invention includes a step of sequentially attaching a first flat plate, a disc spring, and a second flat plate to the tip portion of the shaft having a reduced diameter;
And a step of caulking the tip of the male shaft with a reduced diameter.

  According to the present invention, the first flat plate, the disc spring, and the second flat plate are sequentially attached to the reduced diameter tip portion of the male shaft, and the crimped portion is applied to the reduced diameter tip portion of the male shaft. For this reason, it is possible to prevent abnormal noise such as “knacking” by applying a preload to the cylindrical body with certainty while reducing the number of processing steps by roughening the tolerance management.

  Hereinafter, a telescopic shaft for vehicle steering and a shaft end fixing method according to an embodiment of the present invention will be described with reference to the drawings.

(Overall configuration of vehicle steering shaft)
FIG. 1 is a side view of a steering mechanism portion of an automobile to which a vehicle steering telescopic shaft according to an embodiment of the present invention is applied.

  In FIG. 1, an upper steering shaft portion 120 (a steering column 103 and a swinging shaft 104 rotatably supported by the steering column 103 are attached to a member 100 on the vehicle body side via an upper bracket 101 and a lower bracket 102. A steering wheel 105 attached to the upper end of the steering shaft 104, a lower steering shaft portion 107 connected to the lower end of the steering shaft 104 via a universal joint 106, and a steering shaft joint 108 to the lower steering shaft portion 107. A pinion shaft 109 connected via a pin, a steering rack shaft 112 connected to the pinion shaft 109, and the steering rack shaft 112 is supported to elastically move to another frame 110 of the vehicle body. Steering mechanism from a fixed steering rack support member 113 via 111 is formed.

  Here, the upper steering shaft portion 120 and the lower steering shaft portion 107 use the vehicle steering telescopic shaft (hereinafter referred to as the telescopic shaft) according to the embodiment of the present invention. The lower steering shaft portion 107 is formed by fitting a male shaft and a female shaft. The lower steering shaft portion 107 absorbs axial displacement generated when the automobile travels, and the steering wheel. The performance which does not transmit the displacement and vibration on 105 is required. In such performance, the vehicle body has a sub-frame structure, and the member 100 for fixing the upper part of the steering mechanism and the frame 110 to which the steering rack supporting member 113 is fixed are separated, and the steering rack supporting member 113 is This is required in the case of a structure that is fastened and fixed to the frame 110 via an elastic body 111 such as rubber. As another case, when the steering shaft joint 108 is fastened to the pinion shaft 109, an operator may need to have a telescopic function so that the telescopic shaft is once contracted and then fitted and fastened to the pinion shaft 109. . Further, the upper steering shaft portion 120 at the upper part of the steering mechanism also has a male shaft and a female shaft fitted to each other. The upper steering shaft portion 120 is used for a driver to drive a car. In order to obtain an optimal position, the function of moving the position of the steering wheel 105 in the axial direction and adjusting the position is required, and thus a function of expanding and contracting in the axial direction is required. In all the cases described above, it is possible to reduce the rattling noise of the fitting portion on the telescopic shaft, to reduce the backlash on the steering wheel 105, and to reduce the sliding resistance when sliding in the axial direction. Required.

(Embodiment)
FIG. 2 is a longitudinal sectional view of the telescopic shaft for vehicle steering according to the embodiment of the present invention. FIG. 3 is a cross-sectional view taken along line II-II in FIG.

  As shown in FIG. 2, the telescopic shaft 10 for vehicle steering is composed of a male shaft 1 and a female shaft 2 that are non-rotatable and slidably fitted to each other.

  As shown in FIG. 3, three axial grooves 3 that are equally arranged at intervals of 120 degrees (phase) in the circumferential direction are formed to extend on the outer circumferential surface of the male shaft 1. Correspondingly, three axial grooves 5 that are equally arranged at intervals of 120 degrees (phase) in the circumferential direction are formed to extend on the inner peripheral surface of the female shaft 2.

  Between the axial groove 3 of the male shaft 1 and the axial groove 5 of the female shaft 2, a plurality of rigid spherical bodies 7 (rolling bodies, which roll when the two shafts 1 and 2 move in the axial direction relative to each other). Ball) is installed to roll freely. The axial groove 5 of the female shaft 2 has a substantially arc-shaped cross section or a Gothic arch shape.

  The axial groove 3 of the male shaft 1 is composed of a pair of inclined planar side surfaces 3a and a bottom surface 3b formed flat between the pair of planar side surfaces 3a.

  A leaf spring 9 is provided between the axial groove 3 of the male shaft 1 and the spherical body 7 so as to contact and preload the spherical body 7.

  The leaf spring 9 has a substantially arc-shaped spherical body-side contact portion 9a that contacts the spherical body 7 at two points, and is bent at a predetermined interval in the circumferential direction with respect to the spherical body-side contact portion 9a. The groove surface side contact portion 9b that can come into contact with the planar side surface 3a of the axial groove 3 of the male shaft 1, and the spherical body side contact portion 9a and the groove surface side contact portion 9b are elastically biased in a direction away from each other. And an urging portion 9c bent so as to have a flat bottom surface 9d facing the flat bottom surface 3b of the axial groove 3.

  The urging portion 9c has a substantially U shape and is bent in a substantially arc shape, and the spherical body side contact portion 9a and the groove surface side contact portion 9b are mutually connected by the bent urging portion 9c. Can be elastically biased so as to be separated from each other.

  As shown in FIG. 3, three axial grooves 4 that are equally arranged at intervals of 120 degrees (phase) in the circumferential direction are formed to extend on the outer circumferential surface of the male shaft 1. Correspondingly, three axial grooves 6 that are equally arranged at intervals of 120 degrees (phase) in the circumferential direction are formed to extend on the inner peripheral surface of the female shaft 2.

  A plurality of rigid cylindrical bodies 8 (sliding bodies) that slide between the axial grooves 4 of the male shaft 1 and the axial grooves 6 of the female shaft 2 when the two shafts 1 and 2 move relative to each other in the axial direction. , A needle roller) is interposed with a minute gap. The axial grooves 4 and 6 have a substantially circular arc shape or a Gothic arch shape in cross section.

  In the present embodiment, a small diameter portion 1 a having a reduced diameter is formed at the end of the male shaft 1. The small-diameter portion 1a is provided with a stopper plate 21 that restricts the movement of the cylindrical body 8 in the axial direction.

  The stopper plate 21 includes a disc spring 22 and a pair of first and second flat plates 23 and 24 (that is, washers and plain washers) that sandwich the disc spring 22. In the present embodiment, the same first and second flat plates 23 and 24 can be used, and the types of components can be reduced.

  That is, in the present embodiment, the stopper plate 21 is fitted to the small diameter portion 1a in the order of the first flat plate 23, the disc spring 22, and the second flat plate 24, and then firmly fixed to the small diameter portion 1a by caulking. It is.

  In the present embodiment, the conventional step 16 (FIG. 4) is abolished, so that the tolerance management is rough (coarse). As a premise for this, in the present embodiment, the disc spring 22 is crushed and used.

  Alternatively, the disc spring 22 may be stopped before the disc spring 22 is crushed, and an elastic force may be generated in the disc spring 22.

  When a rubber elastic body is used as in the prior art, it will be crushed everywhere, so a disc spring 22 that becomes rigid when crushed more than a certain stroke is used.

  Further, it is desirable that the disc spring 22 has a hardness of HV400 or less so that the disc spring 22 does not break even when it is flattened.

  As described above, in the present embodiment, it is possible to prevent the abnormal noise such as “knack” by reliably applying a preload to the cylindrical body 8 while reducing the number of processing steps by making the tolerance management rough (rough). .

  In other words, the stopper plate 21 is configured to allow the first flat plate 23 to come into contact with the cylindrical body 8 and to preload moderately so that the cylindrical body 8 does not move in the axial direction by the crushed disc spring 22. Thereby, it is possible to reliably apply a preload to the cylindrical body 8, and it is possible to reliably prevent abnormal noise such as “knack” without moving the cylindrical body 8 in the axial direction during sliding.

  Further, the disc spring 22 can function as an elastic body even when it is crushed. Even if deformation or wear occurs in the contact portion of the end face 15 or the first flat plate 23 with the cylindrical body 8 during use, abnormal noise can be prevented by preloading the disc spring 22.

  Further, in the present embodiment, the six axial grooves 3 and 4 and the axial direction are formed on the outer peripheral surface of the male shaft 1 through gaps in the radial direction in the six axial grooves 5 and 6 of the female shaft 2. Six substantially arc-shaped projections 17 that are coaxially formed are fitted.

  Further, a lubricant may be applied between the axial groove 3 of the male shaft 1, the axial groove 5 of the female shaft 2, the leaf spring 9, and the spherical body 7. A lubricant may also be applied between the axial groove 4 of the male shaft 1, the cylindrical body 8, and the axial groove 6 of the female shaft 2.

  In the telescopic shaft configured as described above, the spherical body 7 is interposed between the male shaft 1 and the female shaft 2, and the spherical body 7 is preloaded to the extent that the female shaft 2 is not rattled by the leaf spring 9. Therefore, the play between the male shaft 1 and the female shaft 2 can be reliably prevented, and when the male shaft 1 and the female shaft 2 move relative to each other in the axial direction, there is no stable play. It is possible to slide with the sliding load.

  At the time of torque transmission, the leaf spring 9 is elastically deformed to constrain the spherical body 7 in the circumferential direction, and the three rows of cylindrical bodies 8 interposed between the male shaft 1 and the female shaft 2 play a main role in torque transmission. Fulfill.

  For example, when torque is input from the male shaft 1, since the preload of the leaf spring 9 is applied in the initial stage, there is no backlash, and the leaf spring 9 generates a reaction force against the torque and transmits the torque. . At this time, overall torque transmission is performed in a state where the transmission torque and the input torque between the male shaft 1, the leaf spring 9, the spherical body 7, and the female shaft 2 are balanced.

  As the torque further increases, the clearance in the rotational direction of the male shaft 1 and female shaft 2 via the cylindrical body 8 disappears, and the subsequent torque increase is transmitted via the male shaft 1 and female shaft 2 to the cylindrical body. 8 communicates. Therefore, it is possible to reliably prevent backlash in the rotational direction of the male shaft 1 and the female shaft 2 and to transmit torque in a highly rigid state.

  As described above, according to the present embodiment, since the cylindrical body 8 is provided in addition to the spherical body 7, most of the load can be supported by the cylindrical body 8 when a large torque is input. Therefore, the contact pressure between the axial groove 5 of the female shaft 2 and the spherical body 7 can be reduced to improve durability, and torque can be transmitted in a highly rigid state at the time of a large torque load. .

  Thus, according to the present embodiment, it is possible to realize a stable sliding load, reliably prevent backlash in the rotational direction, and transmit torque in a highly rigid state.

  The spherical body 7 is preferably a rigid ball. The rigid cylindrical body 8 is preferably a needle roller.

Since the cylindrical body (hereinafter referred to as a needle roller) 8 receives the load by line contact, it has various effects such as a lower contact pressure than a ball that receives a load by point contact. Therefore, the following items are superior to the case where the entire row has a ball rolling structure.
・ The damping effect at the sliding part is larger than that of the ball rolling structure. Therefore, vibration absorption performance is high.
・ Since the needle roller is in minute contact with the male shaft and the female shaft, the fluctuation range of the sliding load can be kept low, and the vibration due to the fluctuation is not transmitted to the steering.
-If the same torque is transmitted, the needle roller can keep the contact pressure lower, so the axial length can be shortened and the space can be used effectively.
-If the same torque is transmitted, the contact pressure of the needle roller can be kept lower, so that an additional step for curing the axial groove surface of the female shaft by heat treatment or the like is unnecessary.
・ The number of parts can be reduced.
・ Assembly can be improved.
・ Assembly costs can be reduced.

In this way, the needle roller serves as a key for torque transmission between the male shaft 1 and the female shaft 2, and is in sliding contact with the inner peripheral surface of the female shaft 2. The use of the needle roller is superior to the conventional spline fitting as follows.
・ Needle rollers are mass-produced products and are very low cost.
-Since the needle roller is polished after heat treatment, it has high surface hardness and excellent wear resistance.
-Since the needle roller is polished, the surface roughness is fine and the friction coefficient during sliding is low, so the sliding load can be kept low.
-Since the length and arrangement of the needle roller can be changed according to the use conditions, it can be used for various applications without changing the design concept.
・ Depending on the conditions of use, the friction coefficient during sliding may have to be further reduced. At this time, if only the needle roller is surface treated, its sliding characteristics can be changed, so the design philosophy is not changed. , Can correspond to various applications.
Since a needle roller having a different outer diameter can be manufactured at a cost of several microns, the gap between the male shaft, the needle roller, and the female shaft can be minimized by selecting the needle roller diameter. Therefore, it is easy to improve the torsional rigidity of the shaft.

  In addition, as described above, the leaf spring 9 is separated from the spherical body-side contact portion 9a that contacts the spherical body 7 at two points, and is spaced apart from the spherical body-side contact portion 9a by a predetermined interval in a substantially circumferential direction. The groove surface side contact portion 9b that contacts the planar side surface 3a of the axial groove 3 of the male shaft 1, and the spherical body side contact portion 9a and the groove surface side contact portion 9b are elastically biased in a direction away from each other. The urging portion 9c and the bottom surface 9d facing the bottom surface 3b of the axial groove 3 are paired on the left and right.

  The urging portion 9c has a substantially U shape and is bent in a substantially arc shape, and the spherical body side contact portion 9a and the groove surface side contact portion 9b are mutually connected by the bent urging portion 9c. Can be elastically biased so as to be separated from each other. Therefore, the spherical spring side contact portion 9a of the leaf spring 9 can be sufficiently bent through the biasing portion 9b, and a sufficient amount of bending can be ensured.

  Accordingly, the leaf spring 9 is provided with a space between the spherical body side contact portion 9a that contacts the spherical body 7 and the groove surface side contact portion 9b that contacts the axial groove 3, and the space is elastically connected therebetween. It is. Therefore, the stress generated at the contact portion between the spherical body 7 and the leaf spring 9 can be relieved at the time of setting, and the desired preload performance can be obtained over a long period by preventing the leaf spring 9 from sag due to permanent deformation. it can.

  Further, if the spherical body side contact portion 9a that contacts the spherical body 7 is formed in a substantially arc shape larger than the radius of the spherical body 7, the contact surface pressure with the spherical body 7 can be lowered than the planar shape, It is preferable.

  Further, the leaf spring 9 can secure a sufficient amount of bending, and the spherical body 7 and the leaf spring 9 are not subjected to an excessive load (stress). In addition, the stress generated at the contact point with the leaf spring 9 can be relieved, so that high stress is not generated, “sagging” due to permanent deformation is prevented, and preload performance is maintained over a long period of time. be able to.

  Further, in the present embodiment, the cylindrical body 8 mainly transmits torque, so that no excessive stress is generated between the male shaft 1, the female shaft 2, the leaf spring, and the spherical body 7.

  In addition, this invention is not limited to embodiment mentioned above, A various deformation | transformation is possible.

1 is a side view of a steering mechanism portion of an automobile to which a telescopic shaft for vehicle steering according to an embodiment of the present invention is applied. It is a longitudinal cross-sectional view of the telescopic shaft for vehicle steering which concerns on embodiment of this invention. FIG. 3 is a transverse sectional view taken along line II-II in FIG. 2. It is a longitudinal cross-sectional view of the telescopic shaft for vehicle steering disclosed in Patent Document 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Male shaft 1a Small diameter part 2 Female shaft 3 Axial groove 3a Planar side surface 3b Bottom surface 4 Axial groove 5 Axial groove 6 Axial groove 7 Spherical body (ball, rolling element)
8 Cylindrical body (needle roller, sliding body)
9 Leaf spring (elastic body)
9a Spherical body side contact part (transmission member side contact part)
9b Groove surface side contact portion 9c Energizing portion 9d Bottom surface 10 Telescopic shaft 11 Stopper plate 12 Axial preload elastic body 13 Flat plate 14 Flat plate 15 End surface 16 Step portion 17 Protruding portion 21 Stopper plate 22 Disc spring 23 First flat plate 24 Second Flat plate

Claims (5)

In the telescopic shaft for vehicle steering, which is incorporated in the steering shaft of the vehicle and the male shaft and the female shaft are slidably fitted to each other,
A first flat plate, a disc spring, and a second flat plate are sequentially attached to the reduced diameter tip of the male shaft,
A telescopic shaft for vehicle steering, characterized in that a caulking process is applied to a reduced diameter end portion of the male shaft. The telescopic shaft is
A preload torque transmission unit that transmits the steering torque while preloading between the two shafts when the steering torque is a predetermined value or less;
2. The vehicle steering expansion and contraction according to claim 1, further comprising: a rigid torque transmission unit configured to transmit the steering torque between the two shafts when the steering torque exceeds a predetermined value by contact of the rigid bodies. axis. The preload torque transmission unit is
Between the outer circumferential surface of the male shaft and the inner circumferential surface of the female shaft, the first torque transmission member is interposed between the at least one row of axial grooves formed through the elastic body,
The rigid torque transmission part is
The second torque transmission member is interposed between at least one other groove direction formed on the outer peripheral surface of the male shaft and the inner peripheral surface of the female shaft, respectively. Telescopic shaft for vehicle steering as described. The first torque transmission member is a rolling element that rolls in the axial relative movement of the two shafts,
The telescopic shaft for vehicle steering according to claim 3, wherein the second torque transmission member is a sliding body that slides and slides when the both wheels move in the axial direction relative to each other. A step of sequentially attaching a first flat plate, a disc spring, and a second flat plate to a reduced diameter tip portion of the shaft;
And a step of caulking the tip of the male shaft with a reduced diameter.

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