JP2005231625A - Extendable shaft for vehicle steering - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an extendable shaft for vehicle steering capable of reliably preventing the rattling between a male shaft and a female shaft in the rotating direction, and transmitting torque in a highly rigid state. <P>SOLUTION: The extendable shaft for vehicle steering is incorporated in a steering shaft of a vehicle, and the male shaft 1 and the female shaft 2 are fitted unrotatably and slidably therein. The extendable shaft is provided with torque transmitting parts provided in the outer peripheral part of the male shaft 1 and the inner peripheral part of the female shaft 2 respectively, and contacted with each other to transmit torque at the time of rotation, and a preload part consisting of a rolling element 7 provided between the outer peripheral part of the male shaft 1 and the inner peripheral part of the female shaft 2 at the position different from those of the torque transmitting parts, that rolls at the time of relative movement between the male shaft and the female shaft in the shaft direction, and an elastic body 8 disposed adjacently to the rolling element 7 in the radial direction, that gives preload to the male shaft 1 and the female shaft 2 through the rolling element 7. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a telescopic shaft for vehicle steering.

  Conventionally, the steering mechanism part of an automobile absorbs the displacement in the axial direction that occurs when the automobile travels, and the expansion and contraction is a spline fit between the male shaft and the female shaft in order not to transmit the displacement or vibration on the steering wheel. The shaft is used as part of the steering mechanism. The telescopic shaft is required to reduce the rattling noise of the spline part, to reduce the rattling on the steering wheel, and to reduce the sliding resistance when sliding in the axial direction.

  Because of this, the nylon spline part of the telescopic shaft is coated with nylon film, and grease is applied to the sliding part to absorb or reduce metal noise, metal hitting sound, etc., and sliding resistance Have been reduced and the play in the rotational direction has been reduced. In this case, as a process of forming the nylon film, cleaning of the shaft → primer application → heating → nylon powder coating → rough cutting → finish cutting → selective fitting with the female shaft is performed. The final cutting process is performed by selecting a die in accordance with the accuracy of the already processed female shaft.

  In Japanese Patent Laid-Open No. 2001-50293 (see Patent Document 1), an elastic body is provided between a groove portion of the inner shaft and a ball in a groove portion provided on the outer peripheral portion of the inner shaft and the inner peripheral portion of the outer shaft. The ball is arranged via a pin, and the ball is rolled during the axial movement to reduce the sliding load of the male shaft and the female shaft. A telescopic shaft for transmitting a vehicle steering is disclosed. Further, the above publication discloses that a male groove and a female groove having a combined cross section with a certain play are provided on the inner shaft and the outer shaft in order to enable transmission of torque even when the ball is broken. ing.

Japanese Patent Laying-Open No. 2001-50293 (pages 7 and 13 and FIG. 12)

  However, in the former, it is necessary to minimize the sliding load of the telescopic shaft while minimizing the backlash, so in the final cutting process, dies with different overpin diameter sizes of several microns are selected according to the female shaft. It will be forced to process, and the processing cost will rise. Further, wear of the nylon film progresses with the progress of use, and the rotational play is increased.

  Further, under conditions where the engine room is exposed to high temperatures, the nylon membrane changes in volume, and the sliding resistance becomes remarkably high and wear is remarkably promoted, so that the backlash in the rotational direction becomes large. Therefore, there is a demand to provide a structure that can suppress the generation of abnormal noise due to backlash in the rotational direction and the deterioration of the steering feeling over a long period of time in a telescopic shaft used for a steering shaft for an automobile.

  Further, in the latter telescopic shaft for vehicle steering disclosed in the latter Japanese Patent Application Laid-Open No. 2001-50293, during normal use, a plurality of balls perform expansion and contraction operations and torque transmission by rolling. For this reason, the number of balls that can withstand the input torque must be provided structurally, and it is difficult to reduce the size of the telescopic shaft for vehicle steering, and it is difficult to take a sufficient collapse stroke at the time of a vehicle collision. There are also disadvantages. Furthermore, since it is composed only of balls, there is a problem that undesirable characteristics appear as a telescopic shaft for vehicle steering in which the sliding load fluctuates.

  The present invention has been made in view of the above-described circumstances, and can realize a stable sliding load, reliably prevent backlash in the rotational direction, and transmit torque in a highly rigid state. An object is to provide a telescopic shaft for steering.

To achieve the above object, a telescopic shaft for vehicle steering according to the present invention is incorporated in a steering shaft of a vehicle, and a telescopic shaft for vehicle steering in which a male shaft and a female shaft are non-rotatably and slidably fitted.
A torque transmitting portion provided on each of the outer peripheral portion of the male shaft and the inner peripheral portion of the female shaft, and contacting each other to transmit torque when rotating;
Roller that is provided between the outer peripheral part of the male shaft and the inner peripheral part of the female shaft at a position different from the torque transmission part, and rolls when the male shaft and the female shaft move relative to each other in the axial direction. A moving body, and a preload portion that is disposed adjacent to the rolling element in a radial direction and includes an elastic body that preloads the male shaft and the female shaft via the rolling body. And

  Moreover, in the telescopic shaft for vehicle steering according to the present invention, it is preferable that the torque transmission parts are always in slidable contact with each other.

  Moreover, in the telescopic shaft for vehicle steering according to the present invention, the torque transmitting portion is formed on the axial ridge having a substantially arc shape in cross section formed on the outer peripheral surface of the male shaft and the inner peripheral surface of the female shaft. It is preferable that the formed cross-sectional shape is constituted by a substantially arc-shaped axial groove.

  Moreover, in the telescopic shaft for vehicle steering according to the present invention, it is preferable that the torque transmission parts are in continuous contact with each other in the axial direction.

  Further, in the telescopic shaft for vehicle steering according to the present invention, the torque transmitting portion may comprise a spline fitting portion or a serration fitting portion formed on the outer peripheral surface of the male shaft and the inner peripheral surface of the female shaft. preferable.

In the telescopic shaft for vehicle steering according to the present invention, the preload portion includes a first axial groove provided on an outer peripheral surface of the male shaft, and the female shaft facing the first axial groove. A second axial groove provided on the inner peripheral surface of
Preferably, the rolling element and the elastic body are disposed between the first and second axial grooves. In the vehicle steering telescopic shaft according to the present invention, the preload portion includes the male shaft. It is preferable that a plurality of torque transmission parts are arranged between the female shafts, and a plurality of the torque transmission parts are arranged between the adjacent preloading parts.

  In the telescopic shaft for vehicle steering according to the present invention, it is preferable that the preload portions are arranged at intervals of 180 degrees in the circumferential direction, and the torque transmission portions are arranged between the preload portions.

  Moreover, in the telescopic shaft for vehicle steering according to the present invention, the preload portions are arranged at equal intervals of 120 degrees in the circumferential direction, and the torque transmission portions are respectively disposed between the preload portions. Is preferred.

  Moreover, in the telescopic shaft for vehicle steering according to the present invention, it is preferable that the torque transmitting portion is disposed at a central portion in the circumferential direction between the preload portions.

In the telescopic shaft for vehicle steering according to the present invention, it is preferable that the rolling element is composed of at least one spherical body.
In the telescopic shaft for vehicle steering according to the present invention, it is preferable that the elastic body is a leaf spring.
In the telescopic shaft for vehicle steering according to the present invention, it is preferable that a solid lubricating film is formed on the outer peripheral portion of the male shaft or the inner peripheral portion of the female shaft.

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

  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. The steering mechanism unit is composed of a pinion shaft 109 connected via a pin and a steering rack 112 connected to the pinion shaft 109 and fixed to another frame 110 of the vehicle body via an elastic body 111. It has been made.

  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 a 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 112 is fixed are separated, and an elastic body 111 such as rubber is provided between them. It is required in the case of a structure that is fastened and fixed via In other cases, 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 to the pinion shaft 109 and fastened. . 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 feeling on the steering wheel 105, and to reduce the sliding resistance when sliding in the axial direction. Required.

(First embodiment)
2 is a cross-sectional view of the telescopic shaft for vehicle steering according to the first embodiment of the present invention, and FIG. 3 is a cross-sectional view taken along line XX of FIG. FIG. 4 is a graph showing the relationship between the stroke of the telescopic shaft for vehicle steering and the sliding load according to the first embodiment.

  As shown in FIGS. 2 and 3, the telescopic shaft for vehicle steering (hereinafter referred to as the telescopic shaft) includes a male shaft 1 and a female shaft 2 that are non-rotatable and slidably fitted to each other.

  In the first embodiment, three axial ridges 4 each having a substantially arc-shaped cross-sectional shape equally spaced at 120 degree intervals in the circumferential direction on the outer peripheral surface of the male shaft 1 are formed to extend, Correspondingly, three axial grooves 6 having a substantially arc-shaped cross-sectional shape extend on the inner peripheral surface of the female shaft 2 at positions facing the three axial ridges 4 of the male shaft 1. The axial ridge 4 and the axial groove 6 are in contact with each other to form a torque transmission portion.

  A substantially U-shaped first axial groove 3 (hereinafter referred to as an axial groove 3) extends between adjacent ones of the three axial ridges 4 on the outer periphery of the male shaft 1. It is formed. On the inner peripheral surface of the female shaft 2, there are three second axial grooves 5 (hereinafter referred to as axial grooves 5) having a substantially arc-shaped cross section so as to face the axial grooves 3 of the male shaft 1. It is formed to extend. A rolling element 7 is interposed between the axial groove 3 of the male shaft 1 and the axial groove 5 of the female shaft 2 via a wave-shaped elastic body 8 for preloading. The rolling element 7 rolls when the male shaft 1 and the female shaft 2 move relative to each other in the axial direction, and is restricted by the elastic body 8 when rotating, so that it does not feel loose.

  The elastic body 8 is pressed against the wall portions 3a, 3a on both sides of the axial groove 3 at the flat portions 8a, 8a on both sides thereof, and restrains the entire elastic body 8 from moving in the circumferential direction. The elastic body 8 pre-loads the rolling element 7 and functions to pre-load the rolling element 7 and the axial ridge 4 to the female shaft 2 to the extent that there is no backlash.

  A stopper plate 9 that locks the elastic body 8 and fixes it in the axial direction is fastened to the male shaft 1 by a crimping portion 10 at an end portion on the side where the male shaft 1 is inserted into the female shaft 2. The stopper plate 9 also serves to prevent the rolling elements 7 from coming off the axial groove 3 of the male shaft 1. Thus, the telescopic shaft for vehicle steering according to the first embodiment is configured.

  Since the telescopic shaft of the first embodiment has such a structure, the male shaft 1 and the female shaft 2 are slidably in contact with each other at each torque transmitting portion due to the presence of the preload portion. When the relative movement of the shaft 1 and the female shaft 2 in the axial direction slides relative to each other, the rolling element 7 can roll.

  FIG. 4 is a graph showing the relationship between the stroke of the telescopic shaft for vehicle steering and the sliding load according to the first embodiment. FIG. 4 shows a comparison of the relationship between the stroke and the sliding load in the case of only ball rolling, the case of only sliding, and the case of the present invention. Thus, it can be seen that the vehicle steering telescopic shaft according to the embodiment of the present invention has a low sliding load, can suppress fluctuations in the sliding load, and has smooth sliding characteristics.

  In addition, the curvature of the axial ridge 4 and the curvature of the axial groove 6 are different, and the axial ridge 4 and the axial groove 6 are formed so as to be in continuous contact in the axial direction at the time of contact. May be. Further, even if the axial ridge 4 formed on the male shaft is formed on the female shaft side and the axial groove 6 formed on the female shaft is formed on the male shaft side, the same as in the first embodiment. Action and effect are obtained. Moreover, the curvature of the axial direction groove | channel 5 and the curvature of the rolling element 7 differ, and both may be formed so that a point contact may be carried out. Further, the rolling element 7 may be a spherical body. Further, the elastic body 8 may be a leaf spring. Further, a lower sliding load can be obtained by applying grease to the sliding surface and the rolling surface.

  The telescopic shaft of the first embodiment configured as described above is superior to the prior art in the following points.

  If the sliding surface is purely sliding as in the prior art, the preload load for preventing rattling could only be kept at a certain level. That is, the sliding load is the friction coefficient multiplied by the preload, and if the preload is increased to prevent rattling and improve the rigidity of the telescopic shaft, the sliding load will increase. This is because it falls into a vicious circle.

  In this respect, in the present embodiment, the preload portion employs a rolling mechanism of the rolling element 7 during the relative movement in the axial direction, so that the preload is increased without causing a significant increase in sliding load. be able to. As a result, it is possible to achieve the prevention of rattling and the improvement of rigidity that could not be achieved conventionally without increasing the sliding load.

  At the time of torque transmission, the axial ridge 4 of the torque transmission portion is in contact with the axial groove 6 to play a role of torque transmission. In the preloading portion, the leaf spring 8 is elastically deformed to cause the spherical body 7 to become male. It is possible to prevent rattling by restraining the shaft 1 and the female shaft 2 in the circumferential direction.

  For example, when torque is input from the male shaft 1, rattling is prevented since the preload of the elastic body 8 is applied in the initial stage.

  As the torque further increases, the axial ridges 4 of the torque transmitting portion and the side surfaces of the axial grooves 6 come into strong contact with each other, and the axial ridges 4 are more strongly subjected to reaction force than the spherical bodies 7, and torque transmission The part mainly transmits torque. Therefore, in the first embodiment, 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.

Since the axial ridges 4 and the axial grooves 6 having a substantially arc-shaped cross section mainly contact and receive the load in the axial direction, the contact pressure is higher than the rolling element 7 that receives the load by point contact. There are various effects such as being able to keep low. Therefore, the following items are superior to the conventional example in which 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.
-If the same torque is transmitted, since the axial ridge 4 can keep the contact pressure lower, the axial length of the torque transmitting portion can be shortened and the space can be used effectively.
-If the same torque is transmitted, since the axial ridge 4 can keep the contact pressure lower, 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.
-Since the torque transmission is mainly handled by the torque transmission part, the number of rolling elements 7 can be reduced and the collapse stroke can be increased.

The following items are superior to the conventional example in which all the rows are spline fitted and all the rows slide in that the rolling elements 7 are partially employed.
・ Sliding load can be kept low because of low frictional resistance.
・ Preload can be increased, and long-term rattling and high rigidity can be achieved at the same time.

(Second Embodiment)
FIG. 5 is a cross-sectional view of the telescopic shaft for vehicle steering according to the second embodiment of the present invention, and FIG. 6 is a cross-sectional view taken along line XX of FIG. The same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  The second embodiment is different from the first embodiment in that a solid lubricating film 11 is formed on the outer peripheral surface of the male shaft 1. In this way, by forming the solid lubricating film 11 on the outer peripheral surface of the male shaft 1, the contact resistance between the axial ridge 4 and the axial groove 6 of the torque transmitting portion can be lowered, so that the total sliding The load (referred to as a sliding load generated during normal use in the structure of the present invention in which both rolling and sliding are applied) can be made lower than that in the first embodiment.

  Also in the case of the second embodiment, the same operation and effect as in the first embodiment can be obtained.

  As the solid lubricant film 11, a powder of molybdenum dioxide is dispersed and mixed in a resin, and the film is formed by spraying or immersing it, and PTFE (tetrafluoroethylene) is dispersed and mixed in the resin. A film or the like formed by baking or dipping is used.

  In the second embodiment, the solid lubricant film 11 is formed over the entire outer peripheral surface of the male shaft 1, but only the outer peripheral surface of the three axial ridges 4 formed on the male shaft 1. May be provided. This is because the main factor of the sliding load is the contact between the axial ridges 4 and the axial grooves 6, and the axial sliding resistance can be lowered by reducing the contact resistance of the contact portion. Because you can.

  Further, a lower sliding load can be obtained by applying grease to the sliding surface and the rolling surface. Moreover, the curvature of the axial ridge 4 and the curvature of the axial groove 6 are different, and the axial ridge 4 and the axial groove 6 are respectively formed so as to continuously contact in the axial direction at the time of contact. May be. Further, even if the axial ridge 4 formed on the male shaft is formed on the female shaft side and the axial groove 6 formed on the female shaft is formed on the male shaft side, the same effect as in the present embodiment is achieved. The effect is obtained. Moreover, the curvature of the axial direction groove | channel 5 and the curvature of the rolling element 7 differ, and both may be formed so that a point contact may be carried out. Further, the rolling element 7 may be a spherical body. Further, the elastic body 8 may be a leaf spring.

(Third embodiment)
FIG. 7 is a cross-sectional view of the telescopic shaft for vehicle steering according to the third embodiment of the present invention, and FIG. 8 is a cross-sectional view taken along the line XX in FIG. The same components as those in the second embodiment are denoted by the same reference numerals, and description thereof is omitted.

  The third embodiment is different from the second embodiment in that the male shaft 1 has a hollow structure (hollow portion 13) to reduce the weight of the entire telescopic shaft for vehicle steering, and the male shaft 1 Since the stopper plate 12 is inserted into the hollow portion 13 of the male shaft 1 and is crimped by having a hollow structure. Other configurations, operations, and effects are the same as those of the second embodiment, and a description thereof will be omitted.

  In the third embodiment, the solid lubricant film 11 is formed over the entire outer peripheral surface of the male shaft 1, but only on the outer peripheral surface of the three axial ridges 4 formed on the male shaft 1. It may be provided. Even if the solid lubricating film 11 is formed on the inner peripheral surface side of the female shaft 2, the same operation and effect can be obtained.

  Moreover, the curvature of the axial ridge 4 and the curvature of the axial groove 6 are different, and the axial ridge 4 and the axial groove 6 are respectively formed so as to continuously contact in the axial direction at the time of contact. May be. In addition, even if the axial ridge 4 formed on the male shaft is formed on the female shaft side and the axial groove 6 formed on the female shaft is formed on the male shaft side, An effect is obtained. Moreover, the curvature of the axial groove | channel 5 and the curvature of the rolling element 7 differ, and both may be formed so that a point contact may be carried out. Further, the rolling element 7 may be a spherical body. Further, the elastic body 8 may be a leaf spring. Further, a lower sliding load can be obtained by applying grease to the sliding surface and the rolling surface.

(Fourth embodiment)
FIG. 9 is a sectional view of the telescopic shaft for vehicle steering according to the fourth embodiment of the present invention. The same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  The fourth embodiment is different from the first embodiment in that a solid lubricating film 11 is formed on the inner peripheral surface of the female shaft 2. Thus, by forming the solid lubricating film 11 on the inner peripheral surface of the female shaft 2, the contact resistance between the axial ridges 4 and the axial grooves 6 of the torque transmitting portion can be lowered, so The dynamic load (referred to as a sliding load generated during normal use in the structure of the present invention in which both rolling and sliding are applied) can be made lower than in the case of the first embodiment.

  In the case of the fourth embodiment, the same operation and effect as in the first embodiment can be obtained.

  As the solid lubricating film 11, a powder of molybdenum dioxide is dispersed and mixed in a resin, and the film is formed by spraying or immersing it, and PTFE (tetrafluoroethylene) is dispersed and mixed in the resin. A film or the like formed by baking or dipping is used.

  In the fourth embodiment, the solid lubricant film 11 is formed over the entire inner peripheral surface of the female shaft 2, but the inner peripheral surface of the three axial grooves 6 formed in the female shaft 2. You may provide only. This is because the main factor of the sliding load is the contact between the axial ridges 4 and the axial grooves 6, and the axial sliding resistance can be lowered by reducing the contact resistance of the contact portion. Because you can.

  Further, a lower sliding load can be obtained by applying grease to the sliding surface and the rolling surface. Moreover, the curvature of the axial ridge 4 and the curvature of the axial groove 6 are different, and the axial ridge 4 and the axial groove 6 are respectively formed so as to continuously contact in the axial direction at the time of contact. May be. Further, even if the axial ridge 4 formed on the male shaft is formed on the female shaft side and the axial groove 6 formed on the female shaft is formed on the male shaft side, the same effect as in the present embodiment is achieved. The effect is obtained. Moreover, the curvature of the axial direction groove | channel 5 and the curvature of the rolling element 7 differ, and both may be formed so that a point contact may be carried out. Further, the rolling element 7 may be a spherical body. Further, the elastic body 8 may be a leaf spring.

(Fifth embodiment)
FIGS. 10A, 10B, and 10C are cross-sectional views of a first example, a second example, and a third example, respectively, of a telescopic shaft for vehicle steering according to a fifth embodiment of the present invention. is there. The same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

“First Example”
In the first embodiment shown in FIG. 10A, in a telescopic shaft for vehicle steering composed of a male shaft 1 and a female shaft 2 that are spline-fitted, a first portion is provided between the male shaft 1 and the female shaft 2. A preload portion equivalent to the embodiment is provided.

  More specifically, as shown in FIG. 10A, a telescopic shaft for vehicle steering (hereinafter referred to as a telescopic shaft) is a male shaft 1 and a female shaft 2 that are spline-fitted so as not to rotate with respect to each other. It consists of.

  In the first embodiment, a plurality of axial ridges 14 for spline fitting are formed on the outer peripheral surface of the male shaft 1, and a spline fitting shaft is formed on the inner peripheral surface of the female shaft 2 correspondingly. A plurality of directional grooves 16 are formed to extend, and the axial ridges 14 and the axial grooves 16 are spline-fitted to form a torque transmission portion.

  A substantially U-shaped first axial groove 3 (hereinafter referred to as an axial groove 3) is formed at one location on the outer peripheral surface of the male shaft 1 in place of the axial ridge 14 for spline fitting. It is. Correspondingly, a substantially arc-shaped second axial groove 5 (hereinafter referred to as an axial groove 5) extends on the inner peripheral surface of the female shaft 2 at a position facing the axial groove 3. Is formed. A rolling element 7 is interposed between the axial groove 3 and the axial groove 5 via a wave-shaped elastic body 8 for preloading. The rolling element 7 rolls when the male shaft 1 and the female shaft 2 move in the axial direction, and is restrained by the elastic body 8 during rotation to prevent rattling.

  The elastic body 8 is pressed against the wall portions 3a, 3a on both sides of the axial groove 3 at the flat portions 8a, 8a on both sides thereof, so that the entire elastic body 8 cannot move in the circumferential direction. The elastic body 8 preloads the rolling element 7 and preloads the rolling element 7 and the axial ridges 14 to the female shaft 2 to the extent that there is no backlash. In this way, the telescopic shaft of the subject example 1 is configured.

  Since the telescopic shaft of the first embodiment has such a structure, the male shaft 1 and the female shaft 2 are slidably in contact with each other at each torque transmitting portion due to the presence of the preload portion. And the female shaft 2 slide relative to each other and the rolling element 7 rolls.

  In the telescopic shaft configured as described above, the axial projection 14 and the axial groove 16 which are torque transmission portions are spline-fitted between the male shaft 1 and the female shaft 2, and the rolling element 7 is made to be an elastic body 8. Is interposed between the axial groove 3 and the axial groove 5, and the rolling element and the axial ridge 14 are preloaded by the elastic body 8 to the extent that there is no backlash with respect to the female shaft 2. .

  When torque is not transmitted, rattling between the male shaft 1 and the female shaft 2 can be reliably prevented, and there is no rattling when the male shaft 1 and the female shaft 2 move relative to each other in the axial direction. The male shaft 1 and the female shaft 2 can be slid in the axial direction with a stable sliding load.

  At the time of torque transmission, the spline fitting portion between the axial ridge 14 and the axial groove 16 of the torque transmitting portion plays the main role of torque transmission, and the elastic body 8 is elastically deformed in the preloading portion so that the spherical body 7 is It is possible to prevent rattling by restraining the shaft 1 and the female shaft 2 in the circumferential direction.

  Other operations and effects are the same as those in the first embodiment, and a description thereof will be omitted.

"Second Example"
In the second embodiment shown in FIG. 10B, a preload portion equivalent to that of the first embodiment is provided on the male steering shaft 1 and the female shaft 2 in the vehicle steering telescopic shaft composed of the male shaft 1 and the female shaft 2 that are spline-fitted. Are arranged at intervals of 180 degrees in the circumferential direction. A plurality of torque transmission portions equivalent to those in the first embodiment are provided between the preload portions.

  Thus, by providing the preload portion at two locations, it is possible to further reduce the sliding load and prevent rattling as compared with the first embodiment. Other configurations, operations, and effects are the same as those in the first embodiment, and a description thereof will be omitted.

“Third Example”
In the third embodiment shown in FIG. 10C, in the vehicle steering telescopic shaft comprising the male shaft 1 and the female shaft 2 that are spline-fitted, the first embodiment is provided between the male shaft 1 and the female shaft 2. The same preload portion as in Fig. 5 is provided at 120 degrees in the circumferential direction. A plurality of torque transmission portions equivalent to those in the first embodiment are provided between the preload portions.

  Thus, by providing the preload portion at three locations in the circumferential direction, the sliding load can be further reduced and rattling can be prevented as compared with the first and second embodiments. Further, since the preload portion is equally arranged at 120 degrees in the circumferential direction, the eccentricity of the shaft can be improved, and the unevenness of the sliding load can be reduced. Other configurations, operations, and effects are the same as those of the first and second embodiments, and the description thereof is omitted.

  In the first to third embodiments, a lower sliding load can be obtained by applying grease to the sliding surface and the rolling surface. Further, even if the axial ridge 14 formed on the male shaft is formed on the female shaft side and the axial groove 16 formed on the female shaft is formed on the male shaft side, the same operation as in the present embodiment is performed. The effect is obtained. Moreover, the curvature of the axial direction groove | channel 5 and the curvature of the rolling element 7 differ, and both may be formed so that a point contact may be carried out. Further, the rolling element 7 may be a spherical body. Further, the elastic body 8 may be a leaf spring.

(Sixth embodiment)
FIGS. 11A, 11B, and 11C are cross-sectional views of the first, second, and third examples of the vehicle steering telescopic shaft according to the sixth embodiment of the present invention, respectively. is there. The same components as those in the fifth embodiment are denoted by the same reference numerals and description thereof is omitted.

  The difference between the sixth embodiment and the fifth embodiment is that a solid lubricating film 11 is formed on the outer peripheral surface of the male shaft 1. Thus, by forming the solid lubricating film 11 on the outer peripheral surface of the male shaft 1, the contact resistance between the axial ridge 14 and the axial groove 16 of the torque transmitting portion can be lowered, so that the total sliding The load (referred to as a sliding load generated during normal use in the structure of the present invention in which both rolling and sliding are applied) can be made lower than in the case of the fifth embodiment. In the case of the sixth embodiment, the same operations and effects as in the fifth embodiment can be obtained.

  As a solid lubricating film, a powder of molybdenum dioxide is dispersed and mixed in a resin, and then sprayed or dipped and baked to form a film, or PTFE (tetrafluoroethylene) is dispersed and mixed in a resin. What formed the film | membrane by baking after spraying or immersion is used.

  Note that a lower sliding load can be obtained by applying grease to the sliding surface and the rolling surface. Further, even if the axial ridge 14 formed on the male shaft is formed on the female shaft side and the axial groove 16 formed on the female shaft is formed on the male shaft side, the same operation as in the present embodiment is performed. The effect is obtained. Moreover, the curvature of the axial direction groove | channel 5 and the curvature of the rolling element 7 differ, and both may be formed so that a point contact may be carried out. Further, the rolling element 7 may be a spherical body. Further, the elastic body 8 may be a leaf spring.

(Seventh embodiment)
12A, 12B, and 12C are cross-sectional views of the first, second, and third examples of the vehicle steering telescopic shaft according to the seventh embodiment of the present invention, respectively. is there. The same components as those in the fifth and sixth embodiments are denoted by the same reference numerals and description thereof is omitted.

  The difference between the seventh embodiment and the fifth embodiment is that a solid lubricating film 11 is formed on the inner peripheral surface of the female shaft 2. Thus, by forming the solid lubricating film 11 on the inner peripheral surface of the female shaft 2, the contact resistance between the axial ridges 14 and the axial grooves 16 of the torque transmitting portion can be lowered, so The dynamic load (referred to as a sliding load generated during normal use in the structure of the present invention in which both rolling and sliding are applied) can be made lower than in the case of the fifth embodiment. In the case of the seventh embodiment, the same operation and effect as in the fifth embodiment can be obtained.

  As a solid lubricating film, a powder of molybdenum dioxide is dispersed and mixed in a resin, and then sprayed or dipped and baked to form a film, or PTFE (tetrafluoroethylene) is dispersed and mixed in a resin. What formed the film | membrane by baking after spraying or immersion is used.

    Note that a lower sliding load can be obtained by applying grease to the sliding surface and the rolling surface. Further, even if the axial ridge 14 formed on the male shaft is formed on the female shaft side and the axial groove 16 formed on the female shaft is formed on the male shaft side, the same operation as in the present embodiment is performed. The effect is obtained. Moreover, the curvature of the axial direction groove | channel 5 and the curvature of the rolling element 7 differ, and both may be formed so that a point contact may be carried out. Further, the rolling element 7 may be a spherical body. Further, the elastic body 8 may be a leaf spring.

  In the fourth to sixth embodiments, the case where the axial ridges and the axial grooves are for spline fitting has been described. However, the same applies for serration fitting or simply for uneven fitting. The effects and effects are obtained.

(Other related matters)
In all the embodiments of the present invention, the solid male shaft may be replaced with a hollow, and the hollow male shaft may be replaced with a solid.

  Moreover, the following can be said in all the embodiments of the present invention. A structure in which the male shaft is prevented from being pulled out and can not be disassembled by crimping the tip of the female shaft inward may be adopted. The rolling element 7 may be heat-treated and polished. You may use what gave the resin film process which contains PTFE (ethylene tetrafluoride) or molybdenum disulfide to the outer peripheral surface of the male shaft 1. A solid or hollow steel material in which the male shaft 1 is manufactured by cold drawing may be used. An aluminum material manufactured by cold extrusion of the male shaft 1 may be used. A solid steel material or aluminum material produced by cold forging the male shaft 1 may be used. A hollow steel material produced by cold drawing the female shaft 2 may be used. When the male shaft is cold forged, it is desirable to apply a metal soap treatment (bonding treatment) to the material. The female shaft may be formed by using a hollow steel material as a raw material, and after metal soap treatment (bonding treatment), the female shaft is drawn or expanded to a desired diameter, and the groove portion may be press-molded. The female shaft 2 may be nitrided. You may use what gave the resin film process which contains PTFE (ethylene tetrafluoride) or molybdenum disulfide to the inner peripheral surface of the female shaft 2.

In all embodiments of the present invention, the following numerical ranges are preferably used.
・ The ball diameter, which is a rolling element, is about Φ3-6mm for applications used in passenger cars.
・ P. of ball diameter and ball and axial ridge. C. D. The ratio is about 1: 3.5 to 5.0.
-The shaft diameter of the male shaft is generally 13 mm or more when using carbon steel for general mechanical structures because the torsional strength generally required for passenger cars is 250 Nm or more.
-The contact pressure of the ball is 1500 MPa or less with no torque applied.
-The contact pressure of the ball is 2000 MPa or less with a torque of 100 Nm applied.
The contact pressure of the axial ridge is 2000 MPa or less with a torque of 100 Nm applied.
The ratio of the plate thickness of the leaf spring, which is an elastic body, to the ball diameter is about 1: 10-20.

In the present invention, the following can be said in comparison with the conventional product in summary.
・ Low cost.
・ Stable low slide load can be obtained.
・ There is no backlash.
・ Excellent wear resistance.
・ Excellent heat resistance.
・ Weight reduction is possible.
・ The mechanism is small.
・ Can be used in all conditions without changing the design concept.

  Japanese Patent Application Laid-Open No. 2001-50293 and German Patent Publication DE 3730393 A1 disclose a structure in which a plurality of balls are interposed in an axial groove formed on a male shaft and a female shaft and preloaded by an elastic body. It is. On the other hand, as described above, the present invention is significantly superior to “when all rows have a ball rolling structure” or “when conventional spline fitting”.

  In addition, in European Patent Publication No. EP1078843A1, the needle roller, its retainer, and a regulator for preventing rattling are structured to prevent rattling, but because of pure sliding sliding, the preload cannot be increased. . Therefore, it is very difficult to prevent rattling and to obtain high rigidity over a long period of time.

On the other hand, in the present invention, as described above, the rolling structure is partially adopted, and the means for preventing backlash is different.
・ Sliding load can be kept low because of low frictional resistance.
・ Preload can be increased, and long-term rattling and high rigidity can be achieved at the same time. Is extremely excellent.

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

(The invention's effect)
As described above, according to the present invention, there is provided a telescopic shaft for vehicle steering capable of reliably preventing backlash in the rotational direction between the male shaft and the female shaft and transmitting torque in a highly rigid state. I can do it.

It is a side view of the steering mechanism part of the automobile to which the telescopic shaft for vehicle steering according to the embodiment of the present invention is applied. It is sectional drawing of the telescopic shaft for vehicle steering which concerns on 1st Embodiment of this invention. It is sectional drawing along the XX line of FIG. It is a graph which shows the relationship between the stroke of the expansion-contraction shaft for vehicle steering which concerns on 1st Embodiment, and a sliding load. It is sectional drawing of the expansion-contraction shaft for vehicle steering which concerns on 2nd Embodiment of this invention. FIG. 5 is a cross-sectional view taken along line XX in FIG. 4. It is sectional drawing of the telescopic shaft for vehicle steering which concerns on 3rd Embodiment of this invention. It is sectional drawing along the XX line of FIG. It is sectional drawing of the telescopic shaft for vehicle steering which concerns on 4th Embodiment of this invention. It is sectional drawing of the expansion-contraction shaft for vehicle steering which concerns on (a) 1st Example, (b) 2nd Example, (c) 3rd Example of 5th Embodiment of this invention. It is sectional drawing of the expansion-contraction shaft for vehicle steering which concerns on (a) 1st Example, (b) 2nd Example, (c) 3rd Example of 6th Embodiment of this invention. It is sectional drawing of the expansion-contraction shaft for vehicle steering which concerns on (a) 1st Example, (b) 2nd Example, (c) 3rd Example of 7th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Male shaft 2 Female shaft 3 1st axial direction groove | channel 3a Wall part 4, 14 Axial protruding item | line 5 2nd axial direction groove | channel 6, 16 Axial direction groove | channel 7 Rolling body 8 Elastic body 8a Flat part 9, 12 Stopper plate DESCRIPTION OF SYMBOLS 10 Clamping part 11 Solid lubricating film 100 Member 101 Upper bracket 102 Lower bracket 103 Steering column 104 Steering shaft 105 Steering wheel 106 Universal joint 107 Lower steering shaft part 108 Steering shaft joint 109 Pinion shaft 110 Frame 111 Elastic body 112 Steering rack 120 Upper Steering shaft

Claims (13)

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 torque transmitting portion provided on each of the outer peripheral portion of the male shaft and the inner peripheral portion of the female shaft, and contacting each other to transmit torque when rotating;
Roller that is provided between the outer peripheral part of the male shaft and the inner peripheral part of the female shaft at a position different from the torque transmission part, and rolls when the male shaft and the female shaft move relative to each other in the axial direction. A preloading portion comprising a moving body and an elastic body that is arranged adjacent to the rolling element in the radial direction and applies preload to the male shaft and the female shaft via the rolling body;
A telescopic shaft for vehicle steering, comprising:   The telescopic shaft for vehicle steering according to claim 1, wherein the torque transmission parts are always in contact with each other.   The torque transmitting portion includes an axial ridge having a substantially arc shape in cross section formed on the outer peripheral surface of the male shaft and an axial groove having a substantially arc shape in cross section formed on the inner peripheral surface of the female shaft. The telescopic shaft for vehicle steering according to claim 1, wherein the telescopic shaft is configured.   The telescopic shaft for vehicle steering according to claim 3, wherein the torque transmission parts are in continuous contact with each other in the axial direction.   2. The vehicle steering expansion and contraction according to claim 1, wherein the torque transmission portion includes a spline fitting portion or a serration fitting portion formed on an outer peripheral surface of the male shaft and an inner peripheral surface of the female shaft. axis. The preload portion includes a first axial groove provided on the outer peripheral surface of the male shaft, and a second axial direction provided on the inner peripheral surface of the female shaft so as to face the first axial groove. Having a groove,
The telescopic shaft for vehicle steering according to claim 1, wherein the rolling element and the elastic body are disposed between the first and second axial grooves. A plurality of the preload portions are disposed between the male shaft and the female shaft,
2. The telescopic shaft for vehicle steering according to claim 1, wherein a plurality of the torque transmitting portions are arranged between the adjacent preload portions.   The telescopic shaft for vehicle steering according to claim 7, wherein the preload portions are arranged at intervals of 180 degrees in the circumferential direction, and the torque transmission portions are arranged between the preload portions.   8. The vehicle steering system according to claim 7, wherein the preload portions are equally arranged at intervals of 120 degrees in the circumferential direction, and the torque transmission portions are respectively disposed between the preload portions. Telescopic shaft.   The telescopic shaft for vehicle steering according to claim 9, wherein the torque transmission portion is disposed at a central portion in the circumferential direction between the preload portions.   The telescopic shaft for vehicle steering according to claim 1, wherein the rolling element comprises at least one spherical body.   The telescopic shaft for vehicle steering according to claim 1, wherein the elastic body comprises a leaf spring.   The telescopic shaft for vehicle steering according to claim 1, wherein a solid lubricating film is formed on an outer peripheral portion of the male shaft or an inner peripheral portion of the female shaft.

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