JP2005114068A - Spline joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact spline joint of large load capacity, capable of reducing the moving resistance in the axial direction S without rattling. <P>SOLUTION: This spline joint 14 comprises an elastic connecting element 19 for elastically connecting an inner shaft 12 and an outer shaft 13 in the rotating direction T through a raceway member 24 composed of a plate spring and a ball 23, and a rigid connecting element 20 for connecting the inner shaft 12 and the outer shaft 13 in the rotating direction T with rigidity by the engagement of a projection 26 of the inner shaft 12 and a recess 27 of the outer shaft 13. When the transmission torque is less than a specific value, clearances L1, L2 as play in the rotating direction T are provided between the projection 26 and the recess 27, the torque is transmitted between the inner shaft 12 and the outer shaft 13 through only the elastic connecting element 19, and the moving resistance can be reduced by utilizing the rolling of the ball 23. When the transmission torque is increased over the specific value, both shafts 12, 13 are connected with rigidity by the rigid connecting element 20. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a spline joint used in an automobile steering device or the like.

  For example, in an automobile steering device, an intermediate shaft is provided between a steering shaft connected to a steering wheel and a steering device. The intermediate shaft has a cylindrical outer shaft and an inner shaft that are fitted to each other. Between the inner shaft and the outer shaft, the above-mentioned spline joint is used to connect the inner shaft and the outer shaft so that the steering torque from the steering wheel can be transmitted and the inner shaft and the outer shaft can move relative to each other in the axial direction. Yes.

In some conventional first spline joints, spline teeth that mesh with each other are formed on the inner periphery of the outer shaft and the outer periphery of the inner shaft, and the spline teeth are relatively slid relative to each other in the axial direction. However, since the spline teeth slide relative to each other, the movement resistance is large, and as a result, vibrations generated in the steering device are easily transmitted to the steering wheel.
Further, as a conventional second spline joint, a groove extending in the axial direction between the outer shaft and the inner shaft in place of the spline teeth in order to suppress the movement resistance in the axial direction between the outer shaft and the inner shaft to be small. In some cases, a plurality of spherical rolling elements are provided between the tracks with play, and torque is transmitted only through the rolling elements.

However, if there is play between the rolling elements and the track, the steering torque applied to the steering wheel will not be transmitted to the steering mechanism until this play is blocked, so the driver will feel rattling and lack of rigidity, Maneuvering stability is degraded.
Therefore, as a conventional third spline joint, there is one that gives a preload elastically to the rolling element in order to remove rattling that occurs in the rolling element (see, for example, Patent Document 1).

Further, as a conventional fourth spline joint, there is one having a rolling element elastically preloaded and a concave line and a convex line that can be engaged to transmit torque when the rolling element is broken (for example, , See Patent Document 2). A play is set between the concave and convex ridges at normal times.
In addition, as a conventional fifth spline joint, a spherical rolling element that is elastically preloaded and interposed between the inner shaft and the outer shaft and the inner shaft and the outer shaft are prevented from rolling. And a cylindrical body interposed between them (for example, see Patent Document 3). The cylindrical body shown in FIG. 2 of Patent Document 3 is arranged with its center axis parallel to the axial direction of the spline joint, capable of transmitting torque without play between the inner shaft and the outer shaft, and in the axial direction. The inner shaft and the outer shaft are always engaged so as to be slidable relative to each other. In addition, the cylindrical body shown in FIG. 23B of Patent Document 3 is interposed between the inner shaft and the outer shaft so as to be able to transmit torque in a state of play and to be slidable in the axial direction.
German Patent Application Publication No. DE37030393A1 Japanese Patent Laying-Open No. 2001-50293 (FIG. 12) International Publication No. WO03 / 031250A1 (FIGS. 2 and 23B)

By the way, the spline joint is required to be both small in size and increased in load capacity. In particular, there is a strong demand for those used in automobiles.
However, in the conventional second and third spline joints, if the load capacity is to be increased, the rolling elements become larger, resulting in an increase in the size of the spline joint.
In addition, the conventional fourth spline joint functions in the same way as the conventional third spline joint in a normal state, and therefore increases in size when an attempt is made to increase the load capacity.

Further, in the conventional fifth spline joint, since the cylindrical body without play is always in contact with the inner shaft and the outer shaft, for example, even when the transmission torque is small, the same as the conventional first spline joint. In addition, the movement resistance when moving in the axial direction is large. In addition, the cylindrical body with play generates rattling and abnormal noise is generated.
SUMMARY OF THE INVENTION An object of the present invention is to provide a small spline joint that has no rattling, can suppress the movement resistance in the axial direction, and has a large load capacity.

  In order to achieve the above object, the present invention provides a spline joint for connecting an inner shaft and an outer shaft fitted together so that torque can be transmitted and relatively moved in an axial direction, and the inner shaft and the outer shaft are opposed to each other. An elastic coupling element including a rolling element interposed between tracks provided at each position, and elastically coupling the inner shaft and the outer shaft via the rolling element in the rotational direction, and either the inner shaft or the outer shaft. A ridge formed on the other and a groove formed on the other and engageable with the ridge, and a rigid coupling element capable of rigidly coupling the inner shaft and the outer shaft in the rotational direction. When the transmission torque between the shafts is less than or equal to a predetermined value, play is provided in the rotational direction between the ridges and recesses of the rigid coupling element, and the torque is transmitted between the inner shaft and the outer shaft only through the elastic coupling element. That it is communicated To.

According to the present invention, in a use state where the transmission torque is equal to or less than a predetermined value, torque is transmitted between both shafts only by the elastic connecting element including the rolling elements, while the inner shaft and the outer shaft are utilized using the rolling elements. Relative movement resistance can be reduced. Moreover, since both the shafts are elastically connected via the rolling elements, it is possible to eliminate rattling between the two shafts due to the rattling of the rolling elements.
When the transmission torque exceeds a predetermined value and the relative displacement in the rotational direction of the inner shaft and the outer shaft increases, the ridges and recesses of the rigid coupling element engage with each other, and both shafts are rigid via the rigid coupling element. Connected. Since it is sufficient for the elastic connecting element to be able to transmit a torque of a predetermined value or less, the elastic connecting element including the rolling elements can be reduced in size, so that the spline joint can be reduced in size.

Preferably, in the present invention, the rolling element may be formed of a steel ball, and the elastic connecting element may include a track member that forms a track and includes a leaf spring, and the track member elastically biases the steel ball. is there. In this case, the rolling member can be elastically biased with a simple structure by giving the raceway member elasticity.
Preferably, in the present invention, the rolling element includes a steel ball, and the elastic coupling element includes a race member that forms a raceway and a biasing means that resiliently biases the race member to the steel ball. There is. In this case, the biasing force of the biasing means can be easily adjusted by the structure in which the biasing means elastically biases the rolling element via the raceway member.

Preferably, the present invention may include locking means for locking the track member axially to the outer shaft or the inner shaft. In this case, the locking member can prevent the track member from being displaced in the axial direction with respect to the inner shaft or the outer shaft as the rolling element rolls.
Preferably, in the present invention, the rolling element may include an elastic body. In this case, it is possible to simplify or eliminate the configuration of the elastic body included in the elastic coupling element by giving the rolling element itself elasticity.

  Preferably, according to the present invention, the convex strip and the concave strip of the rigid connecting element each have a pair of sliding surfaces that can slide with each other, and at least a part of at least one of the pair of sliding surfaces is a composite. In some cases, the resin member may be coated. In this case, the generation of abnormal noise due to the contact between the pair of sliding surfaces can be suppressed by the impact buffering action of the synthetic resin member. For example, when the synthetic resin member has low friction characteristics, it is preferable because the sliding resistance between the pair of sliding surfaces 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 spline joint is described as applied to an intermediate shaft of a vehicle steering apparatus. However, the spline joint can also be applied to an apparatus other than the above-described intermediate shaft.
FIG. 1 is a schematic diagram showing a schematic configuration of a vehicle steering apparatus having a spline joint according to a first embodiment of the present invention.

  Referring to FIG. 1, a vehicle steering apparatus 1 has an intermediate shaft 2. The intermediate shaft 2 is also called an intermediate shaft, and is provided between a steering shaft 4 connected to the steering wheel 3 and a steering mechanism 5 for steering a wheel (not shown). The intermediate shaft 2 functions to transmit a steering torque applied to the steering wheel 3 to steer the wheels from the steering shaft 4 to the rotating shaft 6 of the steering mechanism 5.

  The vehicle steering apparatus 1 includes the above-described steering shaft 4 that transmits steering torque, and a steering column 7 that rotatably supports the steering shaft 4 through the inside. The steering wheel 3 is connected to one end portion of the steering shaft 4, and the above-described steering mechanism 5 is rotated to the other end portion via the first universal joint 8, the intermediate shaft 2, and the second universal joint 9. The shaft 6 is connected. When the steering wheel 3 is steered, the steering torque is transmitted to the steering mechanism 5 via the steering shaft 4 or the like, and thereby the wheel can be steered. Further, the steering column 7 is provided with a steering assisting electric motor 10 capable of driving the steering shaft 4 and a speed reducer 11 driven by the electric motor 10. The electric motor 10 can obtain a steering assist force corresponding to the steering torque. In the vehicle steering device 1, the intermediate shaft 2 is telescopic so that changes in the position of the steering mechanism 5 that occur during travel can be absorbed.

Please refer to FIG. The intermediate shaft 2 includes an inner shaft 12 and a cylindrical outer shaft 13 that are fitted together with play, and a spline joint 14 that connects the inner shaft 12 and the outer shaft 13 so as to be able to transmit torque and move relative to each other in the axial direction S. Is provided.
The outer shaft 13 is formed at a cylindrical shaft portion 15 formed of a metal member such as steel and having a connection hole 15 a and a first end portion 15 b of the shaft portion 15 to form the first universal joint 8. And a connecting portion 16 for the purpose.

The inner shaft 12 is formed of a metal member such as steel and has a cylindrical shaft portion 17 and a connecting portion 18 that is formed on the first end portion 17a of the shaft portion 17 to form the second universal joint 9. And have. The shaft portion 17 of the inner shaft 12 is inserted and fitted into the connection hole 15 a of the shaft portion 15 of the outer shaft 13.
2 and 3, in this embodiment, the spline joint 14 causes the inner shaft 12 and the outer shaft 13 to rotate in the rotational direction T (both in the circumferential direction) so that torque can be transmitted between the inner shaft 12 and the outer shaft 13. An elastic coupling element 19 that is elastically coupled to the inner shaft 12 and the outer shaft 13 and a rigid coupling element 20 that can be rigidly coupled in the rotational direction T. Both the elastic connecting element 19 and the rigid connecting element 20 allow relative movement in the axial direction S of the inner shaft 12 and the outer shaft 13. Further, as will be described later, the rigid connecting element 20 can connect the inner shaft 12 and the outer shaft 13 when the transmission torque exceeds a predetermined value, and can transmit the torque when connecting.

  The elastic connecting element 19 is provided at a position where the inner shaft 12 and the outer shaft 13 face each other, and a plurality of pairs, for example, three pairs of track grooves 21 and 22 as a track extending in the axial direction S, and a plurality of pairs of track grooves. A plurality of rolling members as rolling elements interposed between 21 and 22, for example, a plurality of balls 23 (only a part of which is shown) and a plurality of raceway members each forming a plurality of raceway grooves 21 provided on the inner shaft 12 by leaf springs 24. The inner shaft 12 has a plurality of holding portions 25 formed of grooves extending in the axial direction S for holding the track member 24 corresponding to the plurality of track members 24.

  The rigid connecting element 20 has a ridge 26 and a ridge 27 that can be engaged with each other. The ridges 26 are formed on the inner shaft 12 and extend in the axial direction S, and a plurality of, for example, three are provided. The concave stripes 27 are arranged in pairs so as to be able to engage with the convex stripes 26, are formed on the outer shaft 13 and extend in the axial direction S, and a plurality of, for example, three are provided. The plurality of pairs of protrusions 26 and recesses 27 are configured in the same manner, and are arranged at equal intervals in the circumferential direction.

  The convex stripes 26 and the concave stripes 27 have a trapezoidal cross section. The concave stripe 27 has a pair of tooth surfaces 27a and 27b (only a part is shown). The ridge 26 is arranged to face one tooth surface 27 a of the groove 27 in the circumferential direction, and is opposed to one tooth surface 26 a that can be engaged with the tooth surface 27 a and the other tooth surface 27 b of the groove 27. And the other tooth surface 26b that can be engaged with the tooth surface 27b. The distance between the pair of tooth surfaces 27a and 27b of the concave line 27 in the circumferential direction is a predetermined amount than the distance between the pair of tooth surfaces 26a and 26b of the convex line 26 at the radial position where the distance is measured. It is enlarged and play is provided between the ridges 26 and the ridges 27.

The plurality of pairs of raceway grooves 21 and 22 and the ball 23 are disposed between the ridges 26 and the ridges 27 at equal intervals in the circumferential direction. The plurality of pairs of raceway grooves 21 and 22 and the plurality of balls 23 are configured in the same manner.
The plurality of balls 23 are made of steel balls having the same diameter. A plurality of, for example, several balls 23 are inserted between the corresponding pair of raceway grooves 21, 22, and are held in a row aligned in the axial direction S by the cage 28.

The track groove 22 is formed integrally with the inner peripheral surface of the shaft portion 15 of the outer shaft 13 and has a predetermined length in the axial direction S from the first end portion 15a to the second end portion 15b of the shaft portion 15. It consists of an elongated groove.
The raceway groove 21 is provided on the outer peripheral surface of the shaft portion 17 of the inner shaft 12 via a raceway member 24 and is formed of a concave line formed by the raceway member 24. The raceway groove 21 extends from the first end portion 17a of the shaft portion 17 to the second end portion 17b with a predetermined length in the axial direction S.

Referring to FIG. 4, raceway grooves 21, 22 each have a pair of pieces that oppose each other in the circumferential direction in the cross section. The pair of pieces have a V-shape, and the V-shape is opened outward or inward in the radial direction, and both raceway grooves 21 and 22 face each other. A total of four pieces of the raceway groove 21 and the raceway groove 22 are in contact with the ball 23.
The plurality of track members 24 are configured similarly to each other. Each track member 24 is made of a sheet metal molded product, for example, a pressed product in which polishing is omitted, and in the present embodiment, is made of a plate spring formed of spring steel. The track member 24 forms a track groove 21 and is disposed in the middle portion in the circumferential direction in the cross section and has a V-shaped groove forming portion 29 and a pair of end portions 29a of the groove forming portion 29 in the circumferential direction. A pair of extending portions 30 extending away from each other in the opposite direction. The pair of extending portions 30 are respectively held along the peripheral edge portion 25 a of the holding portion 25, and the groove forming portion 29 of the track member 24 is accommodated in the holding portion 25.

The pair of end portions 29a of the groove forming portion 29 of the track member 24 can be elastically engaged with the peripheral portion 25a of the holding portion 25, and serve as detent means for locking the track member 24 to the inner shaft 12 in the circumferential direction. Function. Thereby, when the torque is received, it can prevent that the track member 24 rattles in the circumferential direction, and the stable operation of the spline joint 14 can be realized.
The holding part 25 is formed deeper in the radial direction than the groove forming part 29 of the track member 24, and a predetermined amount between the bottom of the holding part 25 and the groove forming part 29 of the track member 24 in a state where transmission torque is not applied. When a gap is opened and transmission torque is applied, the track member 24 is elastically deformed and can be displaced by a predetermined amount inward in the circumferential direction and in the radial direction.

With reference to FIGS. 5A to 5C, the operation will be described according to the case where the transmission torque is applied to the outer shaft 13, but the same effect can be obtained when the transmission torque is applied to the inner shaft 12.
Refer to FIG. 5A. When no transmission torque is applied, the track member 24 elastically biases the ball 23 radially outward. Thereby, the inner shaft 12 and the outer shaft 13 are held elastically without rattling. Further, the ball 23 is preloaded in the radial direction and the circumferential direction and is held without rattling. Further, the gap amounts L1 and L2 in the circumferential direction between the mutually facing tooth surfaces of the convex stripes 26 and the concave stripes 27 of the rigid connecting element 20 and on both sides sandwiching the convex stripes 26 are equalized. (L1 = L2).

  Referring to FIG. 5B, when transmission torque is applied to the outer shaft 13, for example, rightward on the paper surface, the raceway groove 22 of the outer shaft 13 urges the ball 23 toward the circumferential direction and the radially inward direction. The ball member 23 and the raceway member 24 are displaced inward in the circumferential direction and the radial direction while the raceway member 24 is elastically deformed via the bearing, and accordingly, the inner shaft 12 and the outer shaft 13 are relatively displaced by a predetermined amount in the circumferential direction. However, torque is transmitted between them.

  When the transmission torque between the inner shaft 12 and the outer shaft 13 is less than or equal to a predetermined value, the relative movement amount in the circumferential direction between the inner shaft 12 and the outer shaft 13 is relatively small, and the ridges 26 of the rigid connecting element 20 A play is provided between the inner shaft 12 and the recess 27 in the rotational direction T, and torque is transmitted between the inner shaft 12 and the outer shaft 13 only through the elastic connecting element 19. The above-described play corresponds to the gap amount L1, and the gap amount L1> 0.

  As described above, in a use state where the transmission torque is less than or equal to a predetermined value, torque is transmitted between the shafts 12 and 13 only by the elastic connecting element 19 including the ball 23, while the inner shaft 12 is utilized by rolling the ball 23. And the relative movement resistance of the outer shaft 13 can be reduced. Further, since both the shafts 12 and 13 are elastically connected via the ball 23, the rattling between the both shafts 12 and 13 due to the rattling of the ball 23 can be eliminated.

  Referring to FIG. 5C, when the transmission torque exceeds a predetermined value and the relative displacement in the rotation direction T of the inner shaft 12 and the outer shaft 13 increases, one tooth surface 26a of the ridge 26 of the rigid connecting element 20 and the concave The corresponding tooth surfaces 27a of the strips 27 are brought into surface contact or line contact with each other and engaged with each other, and both shafts 12 and 13 are rigidly connected via the rigid connecting element 20. The elastic connecting element 19 also connects the shafts 12 and 13, but it is sufficient for the elastic connecting element 19 to be able to transmit a torque equal to or less than a predetermined value, so that the elastic connecting element 19 including the ball 23 can be reduced in size. The spline joint 14 can be reduced in size.

By constituting the race member 24 with a leaf spring and giving the race member 24 elasticity, the ball 23 can be elastically biased with a simple structure.
Since the elastic connecting element 19 can absorb dimensional changes such as wear of the balls 23 and the raceway grooves 21 and 22 that occur with aging, etc., it can absorb rattling over a long period of time. Further, since the elastic connecting element 19 can absorb the dimensional error and assembly error of the ball 23, the raceway grooves 21 and 22, etc., the processing accuracy and assembly of the parts 13 and 24 etc. that form the ball 23 and the raceway grooves 21 and 22 etc. The accuracy can also be lowered. Therefore, the spline joint 14 can be made inexpensive. For example, the conventional polishing of the raceway grooves 21 and 22 can be omitted. Moreover, the assembly by the conventional matching with the ball | bowl 23 and the track grooves 21 and 22 can be abolished.

Since the race member 24 is made of a sheet metal molded product, more preferably a press-work product in which the polishing process is omitted, the race member 24 can be formed at low cost, and the spline joint 14 can be inexpensive.
Please refer to FIG. 6 and FIG. The spline joint 14 is a plurality of members extending radially inward from the end 31 in the axial direction S of the track member 24 as locking means for locking the track member 24 in the axial direction S to the corresponding inner shaft 12. For example, there are two engaging protrusions 32, and a plurality of, for example, two engaging parts 34 provided on the end surface 33 of the inner shaft 12 that respectively engage with the plurality of engaging protrusions 32. Yes. By the locking means, it is possible to prevent the track member 24 from being displaced in the axial direction S with respect to the inner shaft 12 as the ball 23 rolls. Further, the engagement convex portion 32 and the engagement portion 34 can be prevented from being displaced in a stable state by providing a pair of the engagement protrusion 32 and the engagement portion 34 that are separated from each other on both sides of the center line of the track member 24 in the circumferential direction.

  Further, by providing the above-described locking means on both sides in the axial direction S so as to restrict the positional deviations in opposite directions, it is possible to prevent the positional deviation on both sides in the axial direction S. Further, the engaging convex portions 32 are elastically engaged with the engaging portions 34 in the axial direction S, so that the pair of engaging convex portions 32 can sandwich the inner shaft 12. Thereby, it is possible to reliably prevent the race member 24 from rattling, to realize stable rolling of the ball 23, and to use the elasticity of the race member 24 to the corresponding inner shaft 12 when the spline joint 14 is assembled. Temporary holding is possible, and a plurality of track members 24, a plurality of balls 23, and the like are easily assembled between the inner shaft 12 and the outer shaft 13.

  Further, as a retaining means for preventing the raceway member 24 from detaching from the holding portion 25 in the radial direction, a recess 35 as a undulation formed on the corresponding end surface 33 of the inner shaft 12 is engaged with the recess 35. A projection 36 provided on the raceway member 24 is provided as the undulating portion. The protrusion 36 is formed at the front end of the engaging protrusion 32 so as to protrude in the axial direction S so as to face the recess 35, engage with the recess 35, and prevent the track member 24 from moving outward in the radial direction. To do. As a result, the track member 24 can be reliably temporarily held on the inner shaft 12 and the spline joint 14 can be easily assembled. Although not shown in the drawings, the race member 24 may be provided with depressions as undulations, and the inner shaft 12 may be provided with projections as undulations, as the retaining means.

Next, a second embodiment will be described. In the following description, differences from the above-described embodiment will be mainly described, and the description of the same configuration will be omitted and the same reference numerals will be given. The same applies to other embodiments and modifications described later.
Please refer to FIG. The spline joint 14A according to the second embodiment includes an elastic connecting element 19A and the above-described rigid connecting element 20 (see FIG. 3). The elastic connecting element 19A includes a race member 37 made of a rigid member in place of the race member 24 formed by the leaf spring of the first embodiment, and elastically biases the race member 37 to the ball 23. A plurality of elastic members 38 as biasing means are further provided, and this point is different from the elastic connecting element 19 of the first embodiment.

The track member 37 is made of a sheet metal molded product, for example, a pressed product in which polishing is omitted. The track member 37 forms a track groove 21 and has a V-shape in cross section. The track member 37 is accommodated in the holding portion 25.
The elastic member 38 is interposed between the holding portion 25 of the inner shaft 12 and the track member 37 and is made of a plate-like rubber member. A pair of elastic members 38 are provided between a pair of V-shaped pieces of the holding portion 25 and the track member 37 facing each other. The elastic member 38 is provided on one surface and is vulcanized and bonded to the first vulcanized adhesive portion 39 that is vulcanized and bonded to the race member 37 and the holding surface 25 of the inner shaft 12 that is provided on the other surface. And a second vulcanized adhesive portion 40. As a result, the elastic member 38 is fixed to both the track member 37 and the holding portion 25 of the inner shaft 12, and both displacement of the elastic member 38 itself and the track member 37 in all directions are prevented. The elastic member 38 is formed with a predetermined thickness and holds the track member 37 so as to be always away from the holding portion 25.

  In the second embodiment, the race member 37 can elastically bias the ball 23 outward in the radial direction and on both sides in the circumferential direction by the elastic restoring force at the time of compressive elastic deformation of the elastic member 38. Thus, even when no transmission torque is applied, the ball 23 is held in the raceway grooves 21 and 22 with a preload in the radial direction and the circumferential direction without rattling. It is connected without rattling so that it can be transmitted. Further, when the transmission torque is applied, the elastic member 38 is elastically deformed, so that the track member 37 and the ball 23 can be displaced in the radial direction and the circumferential direction as in the first embodiment, and the both shafts 12 and 13 are relatively displaced. However, torque can be transmitted.

Further, the structure in which the elastic member 38 as the urging means elastically urges the ball 23 through the track member 37 makes it easy to adjust the urging force of the urging means. For example, the biasing force can be easily adjusted without affecting the ball 23 by adjusting the thickness, shape, and the like of only the elastic member 38 that is not in contact with the ball 23.
In the second embodiment, the elastic member 38 always secures the gap 41 between the track member 37 and the holding portion 25, but the invention is not limited to this. For example, when the transmission torque increases beyond the first predetermined value, a part of the track member 37 and a part of the holding part 25 may be brought into contact with each other and engaged. When the transmission torque is a value within a range between the first predetermined value and a second predetermined value larger than this value, the elastic member 38 is further elastically deformed, and the track member 37 and the holding portion The remaining portions of the 25 that are not in contact with each other approach each other. When the transmission torque increases beyond the second predetermined value, the connection by the rigid connection element 20 is achieved. In this case, the rigidity of the spline joint 14A can be increased when the transmission torque is larger than the first predetermined value.

  Please refer to FIG. 9 and FIG. The spline joint 14B according to the third embodiment includes an elastic coupling element 19B and the above-described rigid coupling element 20 (see FIG. 3). The elastic connecting element 19B uses an elastic member 38A that is locked to the holding portion 25 by fitting instead of the elastic member 38 that is vulcanized and bonded to the holding portion 25 of the second embodiment. The portion 25 is provided with a fitting recess 42 for locking the elastic member 38A by fitting, and is different from the elastic connecting element 19A of the second embodiment in these points.

  The elastic member 38A has the above-described vulcanized adhesive portion 39 provided on one surface and the fitted portion 43 provided on the other surface and press-fitted into the fitting concave portion 42. Different from the elastic member 38 of the second embodiment. As a result, the elastic member 38A is fixed to the track member 37 and the holding portion 25 of the inner shaft 12, and the displacement of the elastic member 38A itself and the track member 37 in all directions is prevented.

The fitting recess 42 extends in a predetermined length in the axial direction S, and a pair of parallel fittings is provided for each holding portion 25. The end of the fitting recess 42 in the axial direction S is closed and restricts the relative movement of the elastic member 38A in the axial direction S.
Please refer to FIG. 11 and FIG. The spline joint 14C of the fourth embodiment includes an elastic connecting element 19C and the above-described rigid connecting element 20 (see FIG. 3). The elastic connecting element 19C is different from the elastic connecting element 19A of the second embodiment in the following points. That is, instead of the plate-like elastic member 38 vulcanized and bonded to the holding portion 25 of the second embodiment, a plurality of, for example, two annular elastic members 44 that are locked to the holding portion 25 by fitting are used. ing. Accordingly, a plurality of, for example, two annular grooves 45 for locking the elastic member 44 to the holding portion 25 by fitting are provided. Furthermore, a track member 37A is provided instead of the track member 37 of the second embodiment.

The two annular grooves 45 are formed on the outer periphery of the inner shaft 12, are disposed in the vicinity of one and the other ends in the axial direction S of the shaft portion 17 of the inner shaft 12, and are separated from each other. Each annular groove 45 extends in the circumferential direction, and has a plurality of, for example, three arcuate portions 45 a that are divided by the three holding portions 25.
The elastic member 44 is made of an O-ring, has an endless annular shape that is continuous in the circumferential direction, has a circular cross section in the cross section, and is formed by a rubber member as an elastic member. The elastic member 44 has first portions 44 a disposed in the arc-shaped portion 45 a of the annular groove 45 and second portions 44 b disposed in the holding portion 25 alternately in the circumferential direction.

  The elastic member 44 is tightly fitted in the annular groove 45 and is locked in the axial direction S and the radial direction. Inside the holding portion 25, the second portion 44b of the elastic member 44 is a track member. It abuts on 37A and is pressed, elastically deforms in a bent shape, and is interposed between the holding portion 25 and the track member 37A. Due to the elastic restoring force of the elastic member 44, the ball 23 can be elastically urged to the radially outward and circumferential sides via the track member 37A. Therefore, as in the above-described embodiments, when transmission torque is applied, the track member 37A and the ball 23 can be displaced in the radial direction and the circumferential direction, and the torque can be transmitted while the shafts 12 and 13 are relatively displaced.

Moreover, if it is an O-ring, a cheap commercial item can also be utilized for the elastic member 44.
Referring to FIG. 13, the track member 37 </ b> A includes a groove forming portion 46 configured in the same manner as the track member 37, a plurality of, for example, the above-described two engaging convex portions 32, and a retaining device. A plurality of, for example, two of the above-described protrusions 36. The groove forming portion 46 is not vulcanized and bonded to the elastic member 44. The engagement protrusion 32 of the track member 37A extends radially inward from the end of the track member 37A in the axial direction S. Further, the inner shaft 12 is provided with the above-described engaging portion 34 as a locking means and a recess 35 as a retaining means. The protrusion 36 and the recess 35 extend in a direction intersecting the circumferential direction, and also function as a detent means.

  Refer to FIG. The spline joint 14D of the fifth embodiment includes an elastic coupling element 19D and the rigid coupling element 20 described above. The elastic connecting element 19D is different from the elastic connecting element 19 of the first embodiment in the following points. That is, instead of the plurality of balls 23 made of steel balls of the first embodiment, a plurality of balls 47 made of an elastic member such as a synthetic resin member are used. Further, the raceway groove 21 is formed integrally with the inner shaft 12, and the raceway member 24 and the holding portion 25 described in the first embodiment are omitted.

The plurality of balls 47 are formed to have the same diameter, and only the material is different from the ball 23 of the first embodiment. In a state where the inner shaft 12 and the outer shaft 13 are fitted, the ball 47 is sandwiched between the pair of raceway grooves 21 and 22 and is compressed and elastically deformed and press-fitted.
In the fifth embodiment, the inner shaft 12 and the outer shaft 13 can be elastically biased by the elastic restoring force of the ball 47. When the transmission torque is applied, the ball 47 is further elastically deformed, whereby the torque can be transmitted while the shafts 12 and 13 are relatively displaced as in the above-described embodiments.

  Thus, when the ball 47 includes an elastic body, the ball 47 itself can have elasticity, thereby simplifying the configuration of the elastic body included in the elastic connecting element 19D other than the ball 47, Or the structure of the spline joint 14D can be simplified. For example, in this embodiment, the raceway grooves 21 and 22 are formed in the inner shaft 12 and the outer shaft 13, and the raceway member 24 of the first embodiment and the elastic members 38, 38A, and 44 of the second to fourth embodiments are further provided. The simple structure which abolished can be realized.

  As described above, in each embodiment of the present invention, the rigid coupling element 20 is allowed to have play so that the torque is transmitted only by the elastic coupling elements 19, 19A, 19B, 19C, and 19D when the transmission torque is equal to or less than a predetermined value. . As a result, there is no backlash, the movement resistance of the two shafts 12 and 13 in the axial direction S can be reduced, and a small spline joint 14, 14A, 14B, 14C and 14D can be realized with a large load capacity. be able to.

  Further, it is preferable to apply the spline joints 14, 14 </ b> A, 14 </ b> B, 14 </ b> C, 14 </ b> D 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 improved. Moreover, since the movement resistance of the inner shaft 12 and the outer shaft 13 is reduced, the vibration generated in the steering mechanism 5 is reduced. Etc. are not easily transmitted to the steering wheel 3, and a comfortable steering feeling is achieved.

Further, the spline joints 14, 14A, 14B, 14C, and 14D are applied to an electric power steering apparatus in which the steering assisting electric motor 10 is provided in the steering column 7 and the transmission torque of the intermediate shaft 2 tends to increase. This is preferable in that the load capacity of the intermediate shaft 2 can be increased.
The following modifications can be considered. For example, a spring member such as a leaf spring may be used as the urging means in the second to fourth embodiments.

  As the above-described retaining means, projections 48 that can be engaged with the end edge 51 of the track member 37A shown in FIG. 15 are provided on the peripheral edge portions 25a on both sides of the holding portion 25 of the inner shaft 12, and as the locking means, FIG. Further, the engaging convex portion 32 of the track member 37A and the engaging portion 34 of the inner shaft 12 shown in FIG. 17 may be provided. For example, the protrusion 48 is formed by locally plastically deforming the peripheral portion 25a of the holding portion 25, abuts against the end edge 51 of the track member 37A, and the track member 37A moves radially outward. Stop that.

  18 and 19, a pair of engaging convex portions 49 provided at the end portion in the axial direction S of the track member 37A may be used as the locking means. The pair of engaging convex portions 49 are provided at the end portions in the axial direction S of the raceway member 37A, extend from the end portions away from each other in the circumferential direction, and project along the circumferential direction. The pair of engaging convex portions 49 have a strong edge portion 49 b extending in the circumferential direction and intersecting the plate surface. The edge portion 49 b is an end surface 33 as an engaging portion provided on the inner shaft 12. The track member 37A can be locked on one side in the axial direction S. As described above, as the locking means, it is only necessary to provide engaging portions that engage with each other at the ends of the track member and the corresponding inner shaft 12 in the axial direction S corresponding to each other. FIGS. 15 to 19 show the track member 37A of the fourth embodiment, in which a projection 48, an engagement projection 49, and the like are applied. However, in other embodiments, FIGS. You may apply.

  Referring to FIG. 20, a pair of engagement step portions 50 may be provided on the inner shaft 12 as a rotation preventing means, and the engagement step portion 50 and the track member 24 may be engaged. FIG. 20 illustrates a case where the engagement step portion 50 is applied to the first embodiment, and will be described based on this case, but may be applied to other embodiments. The pair of engaging step portions 50 extend along the axial direction S so as to face the extending portions 30 which are both side edges of the track member 24 in the circumferential direction, and elastically engage with the extending portions 30. The rattling of the track member 24 can be reliably regulated on both sides in the circumferential direction. The pair of engaging stepped portions 50 may be formed on a part of the ridge 26 of the rigid connecting element. Further, the pair of engagement step portions 50 are formed to extend along the radial direction and are widened outwardly in the radial direction so that the track member 24 can be easily attached.

  In addition, referring to FIG. 21, the pair of engagement step portions 50 may be formed so as to approach each other as the outer side in the radial direction and the interval therebetween becomes narrower. In FIG. 21, the pair of engagement step portions 50 are formed to be inclined with respect to the radial direction, and the distance L11 between the radial outer portions of the pair of engagement step portions 50 is the radial inner portion. It is formed narrower than the interval L12 and is formed narrower than the interval L13 of the opposing end edges of the track member 24 in the circumferential direction. In this case, the structure can be simplified by integrating the retaining means and the rotation preventing means.

  Referring to FIG. 22, the raceway groove 21 of the first embodiment is formed on the inner shaft 12, the raceway groove 22 is formed by a raceway member 24 instead of the outer shaft 13, and the holding portion 25 is provided on the outer shaft 13. It may be provided. Although not shown, the track member 24 and the holding portion 25 may be provided on both the inner shaft 12 and the outer shaft 13. Similarly, the raceway grooves 21 and 22 of the second to fourth embodiments are formed by corresponding raceway members to provide corresponding elastic members, or the raceway grooves 21 and 22 of the fifth embodiment are formed by raceway members. Also good.

  Along with this, as a locking means, a configuration in which a track member (not shown) held by the outer shaft 13 is locked to the corresponding outer shaft 13 in the axial direction S is considered. What is necessary is just to latch to the shaft 13 or the inner shaft 12 in the axial direction S. Similarly, with regard to the retaining means and the rotation preventing means for the race member, the race member may be locked to the corresponding outer shaft 13 or inner shaft 12 in the radial direction and the circumferential direction. It is also conceivable to omit at least one of the locking means, the retaining means and the rotation preventing means.

  Further, in each of the above-described embodiments, referring to FIG. 23, the convex strip 26 and the concave strip 27 of the rigid connecting element 20 are each a pair of sliding surfaces 26c and 27c that can slide with respect to each other. It is shown in FIG. The sliding surface 27c of the concave strip 27 is provided on a part of the tooth surfaces 27a and 27b. The sliding surface 26 c of the ridge 26 is provided on a part of the tooth surfaces 26 a and 26 b and is covered with a synthetic resin member 52.

The synthetic resin member 52 is made of a coating formed by coating the entire surface of the metallic ridge 26 as a base, and is formed continuously in the circumferential direction T. The synthetic resin member 52 includes one or a plurality of solid lubricants such as a fluororesin such as polytetrafluoroethylene (PTFE), molybdenum disulfide (MoS ₂ ), and a fluorine compound, and has low friction characteristics. The synthetic resin member 52 may include a synthetic resin as a binder.

  Thereby, generation | occurrence | production of the noise resulting from a contact of a pair of sliding surfaces 26c and 27c can be suppressed by the impact buffering effect | action of the synthetic resin member 52. FIG. For example, it is possible to suppress the generation of abnormal noise caused by contact between metal members. For example, when the synthetic resin member 52 has a low friction characteristic, the sliding resistance between the pair of sliding surfaces 26c and 27c can be reduced, so that the movement resistance of the shafts 12 and 13 in a state where the transmission torque is large. Can be further reduced, which is preferable.

  The synthetic resin member 52 may form only the sliding surface 26c on which the synthetic resin member 52 is provided, or may form only a part of the sliding surface 26c. In addition, as shown in FIG. 24, the sliding surface 27 c of the recess 27 may be covered with a synthetic resin member 52. It is also conceivable that the pair of sliding surfaces 26 c and 27 c are both covered with the synthetic resin member 52. Further, as a sliding surface, a pair of sliding surfaces may be provided on the top surface of the protrusion 26 and the bottom surface of the recess 27 so as to be slidable. Thus, when at least a part of at least one of the pair of sliding surfaces 26c and 27c is formed by covering with the synthetic resin member 52, the generation of abnormal noise can be suppressed and the sliding resistance can also be reduced.

  Further, in each of the above-described embodiments, a plurality of pairs as the rigid connecting element 20, for example, two pairs of the ridges 26 and the ridges 27, are provided between the two adjacent pairs of raceway grooves 21 and 22 in the circumferential direction. You may arrange | position and may provide 3 or more pairs. FIG. 25 shows a case where a large number of pairs, for example, seven pairs of convex stripes 26 and concave stripes 27 are arranged. As described above, when a plurality of pairs, more preferably three or more pairs of the ridges 26 and the ridges 27 are disposed between the two adjacent pairs of raceway grooves 21 and 22, the sliding surfaces 26c and 27c. The contact area when they come into contact with each other can be increased, and the contact surface pressure can be reduced. Therefore, it is possible to suppress the occurrence of wear on the sliding surfaces 26c and 27c. Moreover, an increase in the contact area can be achieved without increasing the sliding surfaces 26c and 27c in the radial direction and the axial direction. Further, when at least a part of the sliding surfaces 26c, 27c is covered with the synthetic resin member 52, the durability of the synthetic resin member 52, which usually tends to be worn more than the metal member, can be improved. preferable.

In each of the embodiments described above, the pair of raceway grooves 21 and 22 and the pair of ridges 26 and the ridges 27 are arranged at different positions in the axial direction S so that they overlap each other when viewed from the axial direction S. In addition, the circumferential positions may be aligned with each other.
In each of the above-described embodiments, the ridges 26 may be semicircular in cross section. In this case, the relative movement resistance of the inner shaft 12 and the outer shaft 13 in the axial direction S can be suppressed. Further, the cross-sectional shapes of the ridges 26 and the ridges 27 may be triangular shapes or the like.

Further, in each of the embodiments described above, the recess 27 of the rigid connecting element 20 may be formed on the inner shaft 12 and the protrusion 26 may be formed on the outer shaft 13. The rigid connecting element 20 may have a ridge 26 formed on one of the inner shaft 12 and the outer shaft 13 and a ridge 27 formed on the other and engageable with the ridge 26. .
In each of the above-described embodiments, at least two balls 23 and 47 which are a part of the plurality of balls 23 and 47 inserted into the pair of track grooves 21 and 22 have a large diameter, and the remaining balls 23 and 47 are It is good also as a small diameter. In this case, the large-diameter balls 23 and 47 can be reliably elastically deformed by receiving a relatively large biasing force, and the small-diameter balls 23 and 47 can be easily rolled by receiving a relatively small biasing force. In this state, it is possible to reliably apply a preload between the inner shaft 12 and the outer shaft 13 while suppressing movement resistance in the axial direction S between the inner shaft 12 and the outer shaft 13. In addition, various design changes can be made within the scope of matters described in the claims.

It is a mimetic diagram of a schematic structure of a steering device for vehicles to which a spline joint of a 1st embodiment of the present invention is applied. It is a partial cross section figure of the intermediate shaft shown in FIG. It is III-III sectional drawing of the intermediate shaft shown in FIG. FIG. 3 is an enlarged cross-sectional view of a main part of the intermediate shaft shown in FIG. 2. 5A and 5B are schematic diagrams for explaining the operation of the intermediate shaft shown in FIG. 2, in which FIG. 5A shows a state where no transmission torque is applied, FIG. 5B shows a state where the transmission torque is small, and FIG. 5C shows a state where the transmission torque is large. . It is a disassembled perspective view of the latching means of the edge part of the intermediate shaft shown in FIG. It is sectional drawing of the latching means shown in FIG. It is a principal part expanded sectional view of the intermediate shaft to which the spline joint of 2nd Embodiment of this invention is applied, and shows the cross section equivalent to the cross section shown in FIG. It is a principal part expanded sectional view of the intermediate shaft to which the spline joint of 3rd Embodiment of this invention is applied, and shows the cross section equivalent to the cross section shown in FIG. It is a X direction arrow directional view of the edge part of the inner shaft shown in FIG. It is a principal part expanded sectional view of the intermediate shaft to which the spline joint of 4th Embodiment of this invention is applied, and shows the cross section equivalent to the cross section shown in FIG. It is a top view of the inner shaft shown in FIG. It is a disassembled perspective view of the principal part of the intermediate shaft shown in FIG. It is sectional drawing of the intermediate shaft to which the spline coupling of 5th Embodiment of this invention is applied, and shows the cross section equivalent to the cross section shown in FIG. FIG. 13 is an enlarged cross-sectional view of a main part of an intermediate shaft showing a modification of the retaining means of the present invention, and shows a cross section corresponding to the cross section shown in FIG. 11. It is a disassembled perspective view of the modification of the latching means of this invention. It is sectional drawing of the latching means shown in FIG. It is a disassembled perspective view of the other modification of the latching means of this invention. The top view of the latching means shown in FIG. 18 is shown. FIG. 6 is an enlarged cross-sectional view of a main part of an intermediate shaft showing a modification of the rotation preventing means of the present invention, and shows a cross section corresponding to the cross section shown in FIG. FIG. 7 is an enlarged cross-sectional view of a main part of an intermediate shaft showing another modification of the rotation preventing means of the present invention, and shows a cross section corresponding to the cross section shown in FIG. 4. FIG. 5 is an enlarged cross-sectional view of a main part of an intermediate shaft showing a modification of the first embodiment of the present invention, and shows a cross section corresponding to the cross section shown in FIG. 4. It is a principal part expanded sectional view which shows the modification of the rigid connection element of this invention. It is a principal part expanded sectional view which shows the other modification of the rigid connection element of this invention. FIG. 7 is an enlarged cross-sectional view of the main part of the intermediate shaft shown in accordance with the first embodiment as another modification of the rigid connecting element of the present invention, and shows an enlarged cross section corresponding to the cross section shown in FIG. 3.

Explanation of symbols

12 Inner shaft 13 Outer shaft 14, 14A, 14B, 14C, 14D Spline joint 19, 19A, 19B, 19C, 19D Elastic connecting element 20 Rigid connecting element 21 Track groove (track provided on inner shaft)
22 Track groove (track provided on the outer shaft)
23 balls (rolling elements, steel balls)
24 Track member (Track member made of leaf spring)
26 Projection 26c Sliding surface 27 Concave 27c Sliding surface 32, 49 Engaging projection (locking means)
33 End face (locking means)
34 Engagement part (locking means)
37, 37A Track member 38, 38A, 44 Elastic member (biasing means)
47 balls (rolling elements made of elastic material)
52 Synthetic resin material L1 Clearance (play)
S axis direction T rotation direction

Claims (6)

In a spline joint that connects an inner shaft and an outer shaft that are fitted to each other so as to be able to transmit torque and relatively move in the axial direction,
An elastic coupling element that includes rolling elements interposed between tracks provided respectively at positions opposite to each other of the inner shaft and the outer shaft, and elastically connects the inner shaft and the outer shaft via the rolling elements in a rotational direction;
A ridge formed on one of the inner shaft and the outer shaft and a groove formed on the other and engageable with the ridge, and the inner shaft and the outer shaft can be rigidly connected in the rotation direction. A rigid connecting element,
When the transmission torque between the inner shaft and the outer shaft is equal to or less than a predetermined value, play is provided in the rotational direction between the convex and concave portions of the rigid connecting element, and the inner shaft and the outer shaft are connected only through the elastic connecting element. A spline joint characterized in that torque is transmitted between them. The spline joint according to claim 1,
2. The spline joint according to claim 1, wherein the rolling element is made of a steel ball, and the elastic coupling element includes a race member that forms a raceway and is made of a leaf spring, and the race member elastically biases the steel ball. The spline joint according to claim 1,
2. The spline joint according to claim 1, wherein the rolling element is made of a steel ball, and the elastic connecting element includes a race member that forms a raceway and a biasing means that resiliently biases the raceway member to the steel ball. The spline joint according to claim 2 or 3,
A spline joint comprising a locking means for locking the track member axially to the outer shaft or the inner shaft. The spline joint according to claim 1,
The spline joint, wherein the rolling element includes an elastic body. The spline joint according to any one of claims 1 to 5,
The ridges and recesses of the rigid connecting element each have a pair of sliding surfaces that can slide with each other, and at least a part of at least one of the pair of sliding surfaces is covered with a synthetic resin member. A spline joint characterized by

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