JP2007232056A - Telescopic shaft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a telescopic shaft which improves the torsional stiffness of an inner shaft and an outer shaft fitted with each other so as to relatively move in the axial direction and to transmit a torque, and reduces the resistance for the relative movement of both shafts. <P>SOLUTION: In an intermediate shaft 5 serving as the present telescopic shaft, track groove forming members 20 which have a V-shaped cross section and form track grooves 26 are held in the axial grooves 18 of the inner shaft 16. Balls 21 are arranged between the tracks 26c of the track groove forming members 20 and the tracks 19c of the axial grooves 19 of the outer shaft 17, and come into four point contact with the respective tracks 19c, 26c at two points for the respective tracks. Pairs of corrugated sheet springs 22, 23 are arranged between the tilting surfaces 18a, 18d of the axial grooves 18 of the inner shaft 16 and the counter surfaces 27A, 27B of the track groove forming members 20 opposed to the tilting surfaces 18a, 18d. The energizing directions B1, B2 of the respective corrugated sheet springs 22, 23 coincide with the counter directions A1, A2 of the contact points 21a, 21b, 21c, 21d of the balls 21 for the respective corresponding two points. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a telescopic shaft used in, for example, a vehicle steering apparatus.

  A conventional telescopic shaft has, for example, an inner shaft, a cylindrical outer shaft, and a rolling element interposed between both shafts. An axial groove is formed on the outer periphery of the inner shaft, and a track member that forms the track groove is disposed in the axial groove. Opposite the raceway groove of the raceway member, a raceway groove extending in the axial direction is formed on the inner periphery of the outer shaft. The rolling element is in contact with the raceway groove of the raceway member and in contact with the raceway groove of the outer shaft. In addition, an elastic body is interposed between the raceway member and the axial groove of the inner shaft (see, for example, Patent Documents 1 and 2).

In Patent Document 1, a spherical rolling element comes into contact with a pair of raceway grooves having a circular arc shape in cross section, and an elastic body biases the rolling element outward in the radial direction of the inner shaft via a raceway member.
In Patent Document 2, the raceway member is composed of a pair of long members. In addition, the spherical rolling elements come into contact with the corresponding raceway grooves of the pair of long members at two points, contact the outer raceway raceway grooves at two points, and roll both raceway grooves in a four-point contact state. Move. The elastic bodies urge the rolling elements along the radial direction of the inner shaft via the long members.

In addition, as another conventional telescopic shaft, there is one in which a rolling member rolls on both raceway grooves in a four-point contact state, and a raceway member is formed of an elastic body. Both side edges extending along the longitudinal direction of the track member, which is also an elastic body, are held by the edge of the axial groove of the inner shaft, and the track member elastically moves the rolling element along the radial direction of the inner shaft. Energized.
Japanese Utility Model Publication No. 45-19207 JP 2001-050293 A

However, in Patent Document 1, since the spherical rolling elements are in linear contact with both raceway grooves in an arc shape, the relative movement resistance of both axes is large.
Moreover, in patent document 2, a rolling element contacts both track grooves at four contact points, that is, two pairs of contact points facing each other in a direction crossing each other. The direction in which the elastic body bends with respect to the direction that connects the contact points that form a pair facing each other obliquely intersects at an angle of about 45 degrees. As a result, the torsional rigidity of the telescopic shaft was low.

This problem also exists in the other conventional telescopic shafts.
Furthermore, in Patent Document 2, since the raceway member is divided into a pair of long members, the raceway groove is easily deformed, and as a result, the rolling elements cannot roll smoothly.
Accordingly, an object of the present invention is to provide a telescopic shaft having high torsional rigidity and low relative movement resistance between both shafts.

  The telescopic shaft (5) of the present invention includes an inner shaft (16) and a cylindrical outer shaft (17) fitted together so as to be movable relative to each other in the axial direction (S1) and capable of transmitting torque therebetween. Formed on the outer peripheral surface (16c) of the shaft and the inner peripheral surface (17d) of the outer shaft, respectively, are held in the axial grooves (18, 19) facing each other and the axial groove (18) of the inner shaft. A raceway groove forming member (20) having a V-shaped cross section forming (26), and a raceway track (26c) of the raceway groove forming member and a raceway (19c) of the axial groove (19) of the outer shaft. A rolling element 21 that is in contact with each other at two points, and that has two contact points (21a, 21b, 21c, 21d) with respect to each of the tracks, and a four-point contact, and an inner shaft The bottom surface (18a, 18d) of the axial groove and the opposing surface (27A, 27) of the raceway groove forming member facing this ), And a pair of elastic members (22, 23) for applying a preload to the rolling elements via the raceway groove forming members, and the urging directions (B1, B2) of the respective elastic members correspond to each other. The two contact points coincide with the opposing directions (A1, A2) or form an angle of 5 degrees or less with respect to the opposing directions.

  According to the present invention, since the rolling elements are brought into contact at four points, the relative movement resistance of both shafts can be reduced as compared with the case of line contact. In addition, since the direction in which the two corresponding contact points face each other substantially coincides with the biasing direction of the elastic member, the elastic member is less likely to bend as compared with the conventional case (Patent Document 2). The torsional rigidity can be increased. In order to increase the torsional rigidity, it is possible to use an elastic member having a high spring constant. However, this elastic member generally tends to generate a large stress compared to the case where the amount of bending is the same. As a result, there is a problem that the elastic member is damaged, deformed, or sag. On the other hand, in the present invention, it is not necessary to use an elastic member having a high spring constant in order to increase the torsional rigidity. Therefore, the above-described problems associated with the use of this elastic member can also be solved.

  In the present invention, each of the elastic members includes a long corrugated leaf spring (22, 23) extending along the axial groove of the inner shaft, and the corrugated spring is in a direction orthogonal to the axial direction of the inner shaft ( R1, R2) may be undulating. In this case, the corrugated spring generally requires less stress generated in the corrugated spring than other elastic members when subjected to the same force, and can ensure a large amount of deflection of the corrugated spring. .

  In the present invention, the raceway groove forming member includes a long member (20) extending in the axial direction of the inner shaft, and the raceway groove forming member is a pair of side edges (20b) along the longitudinal direction (S2). And flanges (20c) provided on the respective side edges, and the dropout of the corresponding elastic member from the axial groove of the inner shaft may be restricted by each flange. In this case, the elastic member can be prevented from falling off, and the structure for this can be simplified.

  In the present invention, the raceway groove forming member may have elasticity for applying a preload to the rolling elements. In this case, the preload can be applied to the rolling elements by the elasticity of the raceway groove forming member in addition to the elasticity of the elastic member. As a result, the preload can be applied to the rolling elements in cooperation with the elastic member and the raceway groove forming member, and the stress generated in the elastic member can be reduced.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present embodiment, the description will be given based on the case where the telescopic shaft is an intermediate shaft of the vehicle steering device. However, the present invention is not limited to this, and may be applied to various devices other than the vehicle steering device. it can.
FIG. 1 is a schematic diagram showing a schematic configuration of a vehicle steering apparatus to which an extendable shaft according to an embodiment of the present invention is applied.

  The vehicle steering apparatus 1 includes a steering apparatus 3 that rotatably supports a steering wheel 2 as a steering member and transmits steering torque, and a wheel (not shown) for steering a wheel (not shown) by the steering torque from the steering apparatus 3. For example, it has a steering mechanism 4 composed of a rack and pinion mechanism, and an intermediate shaft 5 provided as a telescopic shaft provided between the steering device 3 and the steering mechanism 4 for transmitting rotation therebetween.

  The steering device 3 includes a steering shaft 6 that transmits steering torque, and a steering column 7 that rotatably supports the steering shaft 6 through the interior thereof. The steering shaft 6 has an upper shaft 8 and a lower shaft 9 which are fitted so as to be movable relative to each other in the axial direction and capable of transmitting torque. The steering wheel 2 is connected to the end of the upper shaft 8 that is one end 6a of the steering shaft 6, and the above-described steering mechanism is connected to the end of the lower shaft 9 that is the other end 6b via the intermediate shaft 5. 4 input shafts 10 are connected. When the steering wheel 2 is steered, the steering torque is transmitted to the input shaft 10 of the steering mechanism 4 through the steering shaft 6, the universal joint 11, the intermediate shaft 5, and the universal joint 12, thereby steering the wheel. Can do.

  Further, the vehicle steering apparatus 1 can obtain a steering assist force according to the steering torque by the electric motor 13 supported by the steering column 7. That is, the steering device 3 is provided in association with the steering shaft 6 and is based on a torque sensor 14 for detecting steering torque, an output signal from the torque sensor 14, a vehicle speed signal from a speed sensor (not shown), and the like. An electric motor 13 for generating a steering assist force, and a speed reducer 15 for decelerating the rotation of the output shaft of the electric motor 13.

When the steering wheel 2 is operated, the steering torque is detected by the torque sensor 14, and the electric motor 13 generates a steering assist force according to the torque detection result and the vehicle speed detection result. The steering assist force is transmitted to the steering shaft 6 via the speed reducer 15 and is transmitted to the steering mechanism 4 along with the movement of the steering wheel 2 to steer the wheel.
In the vehicle steering device 1, the intermediate shaft 5 is configured to be extendable and retractable so as to absorb a change in the position of the steering mechanism 4 with respect to the vehicle body that occurs during traveling or assembly.

The intermediate shaft 5 is also called an intermediate shaft, and connects the universal joint 11 and the universal joint 12 to each other. The intermediate shaft 5 functions to transmit a steering torque applied to the steering wheel 2 to steer the wheels from the steering shaft 6 to the input shaft 10 of the steering mechanism 4. The intermediate shaft 5 has an inner shaft 16 and a cylindrical outer shaft 17.
The inner shaft 16 and the outer shaft 17 are arranged concentrically with each other, and the one end 17a of the outer shaft 17 and the one end 16a of the inner shaft 16 are fitted to each other so as to be relatively movable in the axial direction S1 of the inner shaft 16 and capable of transmitting torque. Are combined. One end of the universal joint 11 is connected to the other end 17 b of the outer shaft 17. One end of the universal joint 12 is connected to the other end 16 b of the inner shaft 16.

FIG. 2 is a vertical cross-sectional view of a main part of the intermediate shaft 5 and shows a II-II cross section of FIG. FIG. 3 is a transverse cross-sectional view showing a III-III cross section of FIG.
The intermediate shaft 5 has a plurality of axial grooves 18 formed on the outer peripheral surface 16 c of the inner shaft 16 and a plurality of axial grooves 19 formed on the inner peripheral surface 17 d of the outer shaft 17. The axial grooves 18 and 19 are provided in the same number as each other, and are opposed to each other to form a pair, and three pairs are provided.

  The intermediate shaft 5 includes a single raceway groove forming member 20 having a V-shaped cross section held in the axial groove 18 of the inner shaft 16 for each of the axial grooves 18 and 19 that are paired with each other, and the raceway groove. A plurality of balls 21 as rolling elements that are interposed between the forming member 20 and the axial groove 19 of the outer shaft 17 and contact at four points, and are interposed between the axial groove 18 of the inner shaft 16 and the raceway groove forming member 20. And corrugated springs 22 and 23 as a pair of elastic members.

In this embodiment, the corrugated springs 22 and 23 urge the ball 21 in the urging directions B1 and B2 via the raceway groove forming member 20, and the urging directions B1 and B2 are described later. The contact points of the two corresponding balls 21 coincide with the opposing directions A1 and A2.
Further, the respective portions 20, 21, 22, and 23 provided for the axial grooves 18, 19 that are paired with each other are similarly configured for the three pairs of axial grooves 18, 19.

Further, the intermediate shaft 5 has a plurality of spline teeth 24 (only part of which are shown) as engagement portions provided on the outer peripheral surface 16 c of the inner shaft 16 and an engagement provided on the inner peripheral surface 17 d of the outer shaft 17. As a part, it has a plurality of spline teeth 25 (only a part is shown).
The plurality of axial grooves 19 on the inner peripheral surface 17d of the outer shaft 17 are arranged at a predetermined interval in the circumferential direction T1 of the outer shaft 17, specifically, are evenly arranged in the circumferential direction T1. The axial groove 19 is formed integrally with the inner peripheral surface 17d of the outer shaft 17, has a V-shaped cross section, and is parallel to the axial direction of the outer shaft 17 (corresponding to the axial direction S1 of the inner shaft 16). It extends straight.

FIG. 4 is a cross-sectional view of a main part of the intermediate shaft 5 shown in FIG.
The axial groove 19 functions as a raceway groove and has a raceway 19c on the surface. The track 19c has a pair of inclined surfaces 19a and 19b as track portions. The pair of inclined surfaces 19a, 19b are spaced apart from each other in the circumferential direction T1 in the cross section and opposed to each other, and are inclined at the same angle with respect to the radial directions R1, R2 and extend in directions intersecting each other. ing. Each inclined surface 19a, 19b extends straight in parallel to the axial direction of the outer shaft 17, and forms a rolling surface on which the ball 21 contacts and rolls. The inclined surfaces 19a and 19b guide the rolling of the ball 21 while restricting the relative movement of the ball 21 with respect to the track 19c to both sides in the radial direction R1 and the circumferential direction T1.

2 and 3, the plurality of axial grooves 18 on the outer peripheral surface 16c of the inner shaft 16 are arranged evenly in the circumferential direction T1, for example, with a predetermined interval in the circumferential direction T1 of the inner shaft 16. ing. The axial groove 18 is formed integrally with the outer peripheral surface 16 c of the inner shaft 16, has a W-shaped cross section, and extends straight in parallel with the axial direction S <b> 1 of the inner shaft 16.
3 and 4, the axial groove 18 functions as a holding groove for holding the corrugated leaf springs 22 and 23. The axial grooves 18 are disposed adjacent to each other in the circumferential direction T and are opposed to each other as a pair of inclined surfaces 18a and 18b as opposed to each other, and are disposed adjacent to each other in the circumferential direction T as a pair of opposed bottoms. The inclined surfaces 18c and 18d and a connecting surface 18e as a bottom for connecting the edges of the pair of inclined surfaces 18b and 18c with a space therebetween. The pair of inclined surfaces 18 a and 18 b cross each other at a right angle and hold the corrugated leaf spring 22. The pair of inclined surfaces 18 c and 18 d intersect with each other at right angles and hold the corrugated leaf spring 23. The axial groove 18 holds the wave plate springs 22 and 23 in an elastically deformable state, and holds the track groove forming member 20 in a biased state through the held wave plate springs 22 and 23 so as to be displaceable. Yes.

FIG. 5 is an exploded perspective view of a main part of the intermediate shaft 5.
The raceway groove forming member 20 is a long member that extends straight in one direction S2, is a plate member having a constant thickness and having an M-shaped cross section, and the inner shaft 16 and the corrugated springs 22 and 23 are It is a separate single member. The track groove forming member 20 is formed to be relatively wide in the width direction S3 in which the two top portions of the M-shape are arranged in the cross section, and relatively in the short direction that is a direction orthogonal to the width direction. It is formed narrow. When viewed from one side along the short direction, one surface of the plate member of the raceway groove forming member 20 can be seen. On one of the surfaces, a raceway groove 26 that forms a groove at the center in the width direction is formed, and on the other surface, a protrusion is formed at the center in the width direction.

The longitudinal direction S2 of the raceway groove forming member 20 is parallel to the axial direction S1 of the inner shaft 16, the width direction S3 of the raceway groove forming member 20 is along the circumferential direction T1 of the inner shaft 16, and The track groove forming member 20 is disposed in the axial groove 18 of the inner shaft 16 such that the track groove 26 is opened toward the radially outer side R1.
The raceway groove forming member 20 has a main portion 20a having a V shape at the center in the width direction S3. The main body portion 20a has a raceway groove 26 formed of a concave strip having a V-shaped cross section formed on the one surface described above. The raceway groove 26 is formed with a constant cross-sectional shape and extends straight along the longitudinal direction S2 with a predetermined length.

  The track groove 26 has a track 26c on the surface. The track 26c has a pair of inclined surfaces 26a and 26b as track portions. Each inclined surface 26a, 26b extends straight in parallel with the longitudinal direction S2, and forms a rolling surface on which the ball 21 contacts and rolls. As will be described later, in a state where the raceway groove forming member 20 is held by the inner shaft 16, the pair of inclined surfaces 26a, 26b are spaced apart from each other in the circumferential direction T1 in the cross section and are disposed to face each other. The balls 21 are inclined at the same angle with respect to the radial directions R1 and R2 and extend in directions intersecting with each other, and restrict the relative movement of the ball 21 with respect to the track 26c to both sides of the inner shaft 16 in the radial direction R2 and the circumferential direction T1 However, the rolling of the ball 21 is guided.

One inclined surface 26a of the raceway groove forming member 20 and one inclined surface 19b of the axial groove 19 of the outer shaft 17 are opposed to each other with a plurality of balls 21 interposed therebetween with a center 21e of the balls 21 interposed therebetween. ing. The other inclined surfaces 26b and 19a are also opposed to each other with a plurality of balls 21 interposed therebetween and a center 21e of the balls 21 interposed therebetween.
The main body 20 a has a pair of opposing surfaces 27 </ b> A and 27 </ b> B formed on the other side opposite to the raceway groove 26. The facing surface 27A is disposed in parallel to and faces the inclined surface 18a as the bottom of the axial groove 18 of the inner shaft 16, and the corrugated spring 22 is interposed therebetween. The facing surface 27B is disposed in parallel to and faces the inclined surface 18d as the bottom of the axial groove 18 of the inner shaft 16, and the corrugated spring 23 is interposed therebetween.

Further, the raceway groove forming member 20 includes a pair of side edges 20b along the longitudinal direction S2 and a flange portion 20c provided on each side edge 20b.
The pair of collar portions 20c are formed integrally with the main body portion 20a. In the cross section, the flange portion 20c extends from the corresponding width direction end portion of the main body portion 20a in a bent shape toward the opposite side to the raceway groove 26 with a predetermined length. One flange portion 20c is opposed to the opposed inclined surface 18b of the axial groove 18 with a predetermined distance corresponding to the dimension in the width direction of the wave spring 22 described later. The other flange 20c is opposed to the opposed inclined surface 18c of the axial groove 18 with a predetermined distance corresponding to the dimension in the width direction of the wave spring 23 described later. The flange portion 20c may be provided continuously in the longitudinal direction S2, or may be provided in a part of the longitudinal direction S2. Each flange 20c restricts the corresponding corrugated springs 22 and 23 from dropping from the axial groove 18 of the inner shaft 16.

  The raceway groove forming member 20 has elasticity for applying a preload to the ball 21. That is, the raceway groove forming member 20 is composed of a leaf spring formed of spring steel. In a state where the raceway groove forming member 20 has undergone elastic deformation so that the angle formed by the pair of inclined surfaces 26a and 26b (which is equal to the angle D2 shown in FIG. 6) is larger than that in the unconstrained state. The raceway groove forming member 20 is incorporated and held between the shafts 16 and 17. In this state, each ball 21 is urged outward in the radial direction by an elastic restoring force that reduces the angle formed by the pair of inclined surfaces 26a and 26b.

  Referring to FIGS. 2 and 5, the raceway groove forming member 20 is a longitudinal direction of the raceway groove forming member 20 as a locking means for locking the raceway groove forming member 20 to the corresponding inner shaft 16 in the axial direction S1. It has the engaging convex part 20d extended toward the opposite side to the track groove 26 from the both ends of S2. Two engaging projections 20d are provided for each end in the longitudinal direction S2. In a state where the raceway groove forming member 20 is held on the inner shaft 16, each engaging convex portion 20 d is engaged with the corresponding end surface 16 f of the inner shaft 16, thereby causing the inner shaft 16 to be opposed to both sides in the axial direction S <b> 1. The positional deviation of the raceway groove forming member 20 is prevented.

  The plurality of balls 21 form a line arranged in a straight line in the axial direction S1 for each pair of tracks 19c and 26c, and are held by a cage 28. In the present embodiment, the three cages 28 corresponding to the three rows of the balls 21 are connected to each other and are integrally formed. The cage 28 regulates the distance between the balls 21 in the axial direction S1 to a predetermined amount, and moves together with the balls 21 in the axial direction S1.

When the inner shaft 16 and the outer shaft 17 move relative to each other in the axial direction S1, the ball 21 rolls on the tracks 19c and 26c while being guided along the tracks 19c and 26c, and the tracks 19c and 26c. Relative to each other in the axial direction S1.
Referring to FIG. 4, the ball 21 has four contact points 21a, 21b, 21c, and 21d, two on each of the tracks 19c and 26c. In other words, the ball 21 is in contact with the contact point 21 a that contacts one inclined surface 19 a of the track 19 c of the axial groove 19 of the outer shaft 17 and the other contact surface 19 b of the track 19 c of the axial groove 19 of the outer shaft 17. The point 21b, a contact point 21c that contacts one inclined surface 26a of the track 26c of the track groove 26 of the track groove forming member 20, and a contact that contacts the other inclined surface 26b of the track 26c of the track groove 26 of the track groove forming member 20. And a point 21d. The contact points 21b and 21c are located on opposite sides of the center 21e of the ball 21. The contact points 21a and 21d are located on opposite sides of the center 21e of the ball 21.

  The corrugated spring 22 is interposed between the inclined surfaces 18 a and 18 b as the bottom of the axial groove 18 of the inner shaft 16 and the facing surface 27 A of the raceway groove forming member 20, and the ball 21 is interposed via the raceway groove forming member 20. Is given a preload. The corrugated spring 23 is interposed between the inclined surfaces 18 c and 18 d as the bottom of the axial groove 18 of the inner shaft 16 and the opposing surface 27 B of the raceway groove forming member 20, and the ball 21 is interposed via the raceway groove forming member 20. Is given a preload. Since the corrugated spring 22 and the corrugated spring 23 are formed in the same shape, the corrugated spring 22 will be mainly described.

  2 and 4, the corrugated spring 22 is a long corrugated spring made of metal that extends long in one direction. The corrugated spring 22 is formed by corrugating a long plate having a rectangular cross section. When viewed along the width direction corresponding to the direction in which the long side of the rectangular cross section extends, the corrugated leaf spring 22 has a waveform. The corrugated spring 22 undulates in a curved direction in a thickness direction which is a direction perpendicular to the longitudinal direction of the corrugated spring 22 and perpendicular to the width direction described above. The tops of the corrugated undulations of the corrugated leaf spring 22 extend along the width direction, and are arranged side by side along the longitudinal direction. The corrugated spring 22 can be adjusted in rigidity by adjusting the height of the undulation (swell) when measured along the thickness direction.

The longitudinal directions of the corrugated springs 22 and 23 are disposed in parallel to the axial direction S1 of the inner shaft 16, and the corrugated springs 22 and 23 are disposed so as to undulate in the radial directions R1 and R2. Further, the balls 21 are moved along the corresponding tracks 19c, 26c between the tops of the undulations at both ends of the corrugated springs 22, 23 in the longitudinal direction.
The corrugated springs 22, 23 have undulating top portions 22a, 22b, 23a, 23b on both sides in the thickness direction. The tops of these undulations function as seats, and are received by the corresponding inner shaft 16 and raceway groove forming member 20 in a state of being incorporated in both shafts 16 and 17. That is, one top portion 22 a of the undulation as one seat of the corrugated spring 22 is received in contact with the inclined surface 18 a of the axial groove 18 of the inner shaft 16, and as the other seat of the corrugated spring 22. The other top portion 22b of the undulation is received in contact with the facing surface 27A of the raceway groove forming member 20. Further, one top portion 23 a of the undulation as one seat of the corrugated spring 23 is received in contact with the inclined surface 18 d of the axial groove 18 of the inner shaft 16, and as the other seat of the corrugated spring 23. The other top 23 b of the undulation is received in contact with the opposing surface 27 B of the raceway groove forming member 20.

  Further, the corrugated springs 22 and 23 are elastically deformed in the thickness direction in a state where they are elastically deformed so that the height of the undulation when measured along the thickness direction is lower than that in the unconstrained state. It is attached in the state that received. The urging direction B1 of the elastic repulsion force of the corrugated leaf spring 22 is parallel to the thickness direction, which is the direction of corrugation, and the corresponding inclined surface 18a and the opposing surface 27A are parallel to the opposing direction. . The urging direction B2 of the elastic repulsion force of the corrugated spring 23 is parallel to the thickness direction, which is the direction of corrugation, and the corresponding inclined surface 18d and the opposing surface 27B are parallel to each other. .

In the present embodiment, the urging direction B1 of the corrugated leaf spring 22 coincides with the direction A1 in which the two corresponding contact points 21b and 21c face each other. Further, the urging direction B2 of the corrugated spring 23 coincides with the direction A2 in which the two corresponding contact points 21a and 21d are opposed to each other.
The urging direction B1 of the corrugated leaf spring 22 may form an angle of 5 degrees or less with respect to the direction A1 in which the two corresponding contact points 21b and 21c face each other. Further, the urging direction B2 of the corrugated leaf spring 23 may form an angle of 5 degrees or less with respect to the direction A2 where the two corresponding contact points 21a and 21d are opposed to each other. In the present embodiment, a description will be given based on a case where the urging direction B1 coincides with the facing direction A1 and the urging direction B2 coincides with the facing direction A2.

  The raceway groove forming member 20 can elastically urge the balls 21 to both sides in the radial outer direction R1 and the circumferential direction T1 by the elastic restoring force at the time of the compression elastic deformation of the corrugated springs 22 and 23. Thereby, even in a state where no transmission torque is applied, the ball 21 is held in the raceway groove 26 and the axial groove 19 without being rattled by being preloaded in the radial directions R1, R2 and the circumferential direction T1, Both shafts 16 and 17 are connected without rattling so that torque can be transmitted. When the transmission torque is applied, the corrugated springs 22 and 23 are elastically deformed, whereby the raceway groove forming member 20 and the ball 21 can be displaced in the radial directions R1 and R2 and the circumferential direction T1, and the two shafts 16 and 17 are relative to each other. Torque can be transmitted while being displaced.

FIG. 6 is a schematic view of the main part shown in FIG. With reference to FIG. 6, in the present embodiment, an angle D1 formed by the pair of inclined surfaces 18a and 18d of the axial groove 18 of the inner shaft 16 in the cross section is a pair of opposed surfaces 27A and 27A of the raceway groove forming member 20. It is smaller than the angle D2 formed by 27B by a predetermined angle (D1 <D2). In this case, it is preferable to increase the torsional rigidity of the intermediate shaft 5.
That is, the wave spring 22 tends to hit one side at the position P1 of the corresponding facing surface 27A. When torque is transmitted in such a state, the force that generates this torque is transmitted in the ball 21 along the line L1 passing through the corresponding pair of contact portions 21b and 21c of the ball 21, and the above-described line L1 Further, the raceway groove forming member 20 and the wave spring 22 are transmitted through the region of the radially outer side R1 of the inner shaft 16 (the hatched portion in FIG. 6). When the force acts through the region of the radially outer side R1 of the inner shaft 16 from the line L1, the arm length of the torque becomes longer than when the force acts on the line L1, so the corrugated leaf spring As a result, the amount of deformation applied to the corrugated spring 22 can be small, which is preferable for increasing the rigidity of the intermediate shaft 5.

  In addition to the state in which the wave spring 22 hits at the position P1 as described above, for example, the wave spring 22 hits the corresponding inclined surface 18a (not shown, but is in a state of hitting at the position P2) and the like. It is also conceivable that the elastic compression deformation amount of the wave plate spring 22 is biased in the width direction of the wave plate spring 22 and at least one of the states in which the elastic compression deformation amount on the radially outer side is increased. In these cases, a line of action of a typical force (synthetic force) passing through the corrugated spring 22 passes through the region of the radially outer side R1 of the inner shaft 16 with respect to the line L1, and the above-described action is similarly performed. can get. In addition, the above-described operation is similarly applied to the wave spring 23.

2 and 3, the spline teeth 24 and 25 are spline-fitted with each other, that is, by being slidable relative to each other in the axial direction S1 and meshing with each other, the inner shaft 16 is engaged. Torque can be transmitted between the outer shaft 17 and the outer shaft 17.
Each spline tooth 24 of the inner shaft 16 has a trapezoidal cross section, and extends from the end portion 16f of the inner shaft 16 in the axial direction S1 with a predetermined length. A plurality of spline teeth 24 are arranged between adjacent axial grooves 18 in the inner shaft 16 and are arranged in the circumferential direction T1. Each spline tooth 24 has a pair of tooth surfaces 24a, 24b (only a part is shown).

Each spline tooth 25 of the outer shaft 17 has a trapezoidal cross section, and extends from the opening end 17f of the outer shaft 17 in the axial direction S1 with a predetermined length. A plurality of spline teeth 25 are arranged between adjacent axial grooves 19 on the outer shaft 17 and are arranged in the circumferential direction T1. Each spline tooth 25 has a pair of tooth surfaces 25a and 25b (only a part is shown).
Each tooth surface 24a, 24b, 25a, 25b crosses the circumferential direction T1. One tooth surface 24a of the spline teeth 24 and 25 and one tooth surface 25a of the spline teeth 25 are opposed to each other, and the other tooth surface 24b of the spline teeth 24 and the other tooth surface 25b of the spline teeth 25 are They are facing each other.

  The intermediate shaft 5 is elastically biased by the corrugated springs 22 and 23 and the raceway groove forming member 20 when no torque is applied between the inner shaft 16 and the outer shaft 17 or when a torque of a predetermined value or less is applied. The inner shaft 16 and the outer shaft 17 are elastically connected to each other in the circumferential direction T1 through the balls 21, while play is provided between the tooth surfaces of the spline teeth 24 and 25 in the circumferential direction T1. By connecting both the shafts 16 and 17 via the balls 21 only, the relative movement resistance between the inner shaft 16 and the outer shaft 17 in the axial direction S <b> 1 is suppressed to be small, and the torque between the inner shaft 16 and the outer shaft 17 is reduced. Is transmitted.

When a large torque is applied exceeding a predetermined value, the corrugated leaf springs 22 and 23 and the raceway groove forming member 20 are bent and the shafts 16 and 17 are rotated relative to each other by a minute amount so that the spline teeth 24 and 25 are engaged with each other. The shafts 16 and 17 are rigidly connected, torque is transmitted by the spline teeth 24 and 25, and the ball 21 also contributes to torque transmission between the shafts 16 and 17.
As described above, in the present embodiment, the intermediate shaft 5 as the telescopic shaft includes the inner shaft 16 and the cylindrical outer shaft 17 that are fitted so as to be relatively movable in the axial direction S1 and capable of transmitting torque therebetween. Formed on the outer peripheral surface 16c of the inner shaft 16 and the inner peripheral surface 17d of the outer shaft 17, respectively, are held in the axial grooves 18 and 19 facing each other and the axial groove 18 of the inner shaft 16 to form a track groove 26. A raceway groove forming member 20 having a V-shaped cross section, and a raceway 26c of the raceway groove 26 of the raceway groove forming member 20 and a raceway 19c of the axial groove 19 of the outer shaft 17, both raceways 19c and 26c are both disposed. A ball 21 as a rolling element that makes contact at two points and has two contact points 21a, 21b, 21c, and 21d with respect to each of the tracks 19c and 26c, and an axial groove of the inner shaft 16 Inclined surface 18a as the bottom of 18 18 d and corrugated springs 22, 23 as a pair of elastic members that are interposed between the facing surfaces 27 A, 27 B of the raceway groove forming member 20 facing this and apply a preload to the ball 21 via the raceway groove forming member 20. And. The urging directions B1 and B2 of the corrugated leaf springs 22 and 23 coincide with the opposing directions A1 and A2 of the two corresponding contact points 21a, 21b, 21c, and 21d, respectively, or the opposing directions A1, It forms an angle of 5 degrees or less with respect to A2.

  According to this embodiment, since the ball 21 is brought into contact with four points, the relative movement resistance of both the shafts 16 and 17 can be reduced as compared with the case of making a line contact. In addition, the facing direction A1 of the two corresponding contact points 21b and 21c and the urging direction B1 of the corresponding corrugated spring 22 substantially coincide, and the two corresponding contact points 21a and 21d are opposed to each other. Since the urging direction B2 of the corrugated spring 23 corresponding to the direction A2 substantially coincides, the corrugated springs 22 and 23 are less likely to bend as compared with the conventional case (Patent Document 2), and as a result, twisting occurs. The rigidity can be increased. It is also conceivable to use an elastic member having a high spring constant in order to increase the torsional rigidity. However, this elastic member generally has a tendency to generate a large stress compared with the case where the amount of bending is the same, and as a result, there is a problem that the elastic member is broken, deformed, or sag. On the other hand, in the present embodiment, it is not necessary to use an elastic member having a high spring constant in order to increase the torsional rigidity. Therefore, the above-described problems associated with the use of this elastic member can also be solved.

  In the present embodiment, the elastic member includes long corrugated springs 22 and 23 extending along the axial groove 18 of the inner shaft 16, and the corrugated spring is orthogonal to the axial direction S <b> 1 of the inner shaft 16. It undulates in radial directions R1 and R2 as directions. In this case, the corrugated springs 22 and 23 are generally less stressed in the corrugated springs 22 and 23 than other elastic members (not shown) when subjected to the same force. A large amount of bending of the springs 22 and 23 can be ensured.

  Further, the raceway groove forming member 20 of the present embodiment includes a long member extending in the axial direction S1 of the inner shaft 16, and the raceway groove forming member 20 includes a pair of side edges 20b along the longitudinal direction S2 and each side. Including the flanges 20c provided on the edge 20b, and the flanges 20c restrict the corrugated leaf springs 22 and 23 from falling off the axial grooves 18 of the inner shaft 16. As a result, it is possible to prevent the corrugated leaf springs 22 and 23 from falling off, and the structure for this can be simplified.

  Further, the raceway groove forming member 20 of the present embodiment has elasticity for applying a preload to the ball 21 as a rolling element. In this case, a preload can be applied to the ball 21 by the elasticity of the raceway groove forming member 20 in addition to the elasticity of the corrugated springs 22 and 23. As a result, the preload can be applied to the ball 21 in cooperation with the corrugated springs 22 and 23 and the raceway groove forming member 20, and the stress generated in the corrugated springs 22 and 23 can be reduced. .

Further, in the present embodiment, when the transmission torque becomes a predetermined value or more, the torque is transmitted by the spline teeth 24 and 25 as engaging portions that engage with each other. Thereby, large load capacity is realizable, suppressing the load concerning wave track springs 22 and 23 as raceway groove formation member 20 and an elastic member.
Further, when the spline teeth 24 and 25 mesh with each other, for example, the amount of bending of the corrugated leaf springs 22 and 23 is sufficient as the amount of clearance between the tooth surfaces of the spline teeth 24 and 25. The size of 22 and 23, and thus the cross-sectional area of the axial groove 18, can be small. As a result, it is preferable to keep the torsional rigidity of the intermediate shaft 5 high. In each figure, the axial groove 18 is exaggerated.

Moreover, it is preferable to apply this telescopic shaft to the vehicle steering apparatus 1. In this case, the driver does not feel rattling or lack of rigidity, and the steering stability can be enhanced, and a comfortable steering feeling is achieved.
Further, the corrugated springs 22 and 23 elastically bias the ball 21 through the raceway groove forming member 20. For example, the biasing force can be easily adjusted without affecting the ball 21 by adjusting the thickness, shape, and the like of only the corrugated springs 22 and 23.

Further, since the corrugated leaf springs 22 and 23 are metal leaf springs, there is no risk of problems such as creep occurring in the resin member. Therefore, the elastic repulsion force does not decrease over a long period of time.
In addition, the following modifications can be considered about this embodiment. In the following description, differences from the above-described embodiment will be mainly described, and the same components are denoted by the same reference numerals and description thereof is omitted.

  For example, it is possible to eliminate the spline teeth 24 and 25. Further, the axial grooves 18 and 19 of the inner shaft 16 and the outer shaft 17 may be provided at two places or at four or more places. Moreover, at least one of the inner shaft 16 and the outer shaft 17 may have a plurality of members. For example, the inner shaft 16 is a shaft member that forms the general shape of the inner shaft 16 and a member that is formed separately from the shaft member and is fixed so as to be able to move integrally with the shaft member. 18 and a member on which at least one of the spline teeth 24 is formed. Similarly to the inner shaft 16, the outer shaft 17 may be composed of a plurality of members.

As the raceway groove forming member 20, a configuration in which at least a part of the flange portion 20c is eliminated can be considered. Further, the angle D2 formed by the pair of opposed surfaces 27A and 27B of the raceway groove forming member 20 may be equal to the angle D1 formed by the pair of inclined surfaces 18a and 18d of the axial groove 18, or from the angle D1. Is also possible.
As an elastic member, it is also conceivable to use a leaf spring having a shape other than the wave leaf spring instead of the wave leaf springs 22 and 23. In addition, various design changes can be made within the scope of matters described in the claims.

It is a mimetic diagram showing a schematic structure of a steering device for vehicles to which a telescopic shaft of one embodiment of the present invention is applied. It is a longitudinal cross-sectional view of the principal part of the intermediate shaft shown in FIG. FIG. 3 is a transverse sectional view showing a III-III section shown in FIG. 2. FIG. 4 is a cross-sectional view of the main part of the intermediate shaft shown in FIG. 3. It is a disassembled perspective view of the principal part of the intermediate shaft shown in FIG. It is a schematic diagram of the principal part shown in FIG.

Explanation of symbols

  5 ... Intermediate shaft (expandable shaft), 16 ... Inner shaft, 16c ... Outer peripheral surface, 17 ... Outer shaft, 17d ... Inner peripheral surface, 18, 19 ... Axial groove, 18a, 18b, 18c, 18d ... Inclined surface ( Bottom), 18e ... connection surface (bottom), 19c, 26c ... raceway, 20 ... raceway groove forming member (long member), 20b ... side edge, 20c ... collar, 21 ... ball (rolling element), 21a, 21b, 21c, 21d ... contact point, 22, 23 ... corrugated leaf spring (elastic member), 26 ... raceway groove, 27A, 27B ... facing surface, A1, A2 ... facing direction, B1, B2 ... urging elastic member Direction, R1, R2 ... radial direction (direction orthogonal to the axial direction of the inner shaft), S1 ... axial direction, S2 ... longitudinal direction

Claims (4)

An inner shaft and a cylindrical outer shaft that are fitted in such a manner as to be relatively movable in the axial direction and capable of transmitting torque between each other;
An axial groove formed on each of the outer peripheral surface of the inner shaft and the inner peripheral surface of the outer shaft and facing each other;
A track groove forming member having a V-shaped cross section that is held in the axial groove of the inner shaft and forms a track groove;
This track groove forming member is interposed between the track groove track of the track groove and the axial groove track of the outer shaft, both tracks contact each other at two points, and each track has two contact points. Rolling elements in contact with four points;
A pair of elastic members interposed between the bottom of the axial groove of the inner shaft and the facing surface of the raceway groove forming member facing the inner groove, and applying a preload to the rolling elements via the raceway groove forming member,
The elastic shaft is characterized in that the urging direction of each elastic member coincides with the opposing direction of two corresponding contact points or forms an angle of 5 degrees or less with respect to the opposing direction. The telescopic shaft according to claim 1,
Each of the elastic members includes a long corrugated spring that extends along the axial groove of the inner shaft, and the corrugated spring is undulated in a direction perpendicular to the axial direction of the inner shaft. shaft. The telescopic shaft according to claim 2,
The raceway groove forming member includes a long member extending in the axial direction of the inner shaft,
The raceway groove forming member includes a pair of side edges along the longitudinal direction and flanges provided on each side edge, and the dropout of the corresponding elastic member from the axial groove of the inner shaft is regulated by each flange. Stretchable shaft characterized by The telescopic shaft according to any one of claims 1 to 3,
The raceway groove forming member has elasticity for applying a preload to the rolling elements, and a telescopic shaft.

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