JP2007064404A - Fixed constant velocity universal joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixed constant velocity universal joint formed in a high angle specification and having less rotation backlash. <P>SOLUTION: This fixed constant velocity universal joint 8 comprises a pair of fixed constant velocity universal joints 8A, 8B. Each of the fixed constant velocity universal joints 8A, 8B comprises an outer ring 10 having ball grooves 14 in the inner peripheral surface 12, an inner ring 20 having ball grooves 24 in the outer peripheral surface 22, balls 30 interposed between the ball grooves 14 of the outer ring 10 and the ball grooves 24 of the inner ring 20, a cage 40 having pockets 46 for storing the balls 30, and a clearance reducing mechanism 50 for eliminating a rotation backlash by axially displacing the inner ring 20 relative to the cage 40. The outer rings 10 of the pair of fixed constant velocity universal joints are formed integrally with each other. The constant velocity universal joint comprises a centering mechanisms 60 for roughly making equal the operating angles θ of the pair of fixed constant velocity universal joints 8A, 8B to each other. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fixed type constant velocity universal joint, and can be used for applications such as a steering joint, which always use a high angle and require backlash filling characteristics.

  Constant velocity universal joints are roughly classified into fixed types that allow only angular displacement between the input and output shafts, and slide types that allow angular displacement and axial displacement. Each model is selected according to the application and usage conditions. . As a fixed type constant velocity universal joint, a Rzeppa type (hereinafter referred to as “BJ”) and an undercut free type (hereinafter referred to as “UJ”) are widely known.

  Both BJ and UJ are incorporated between an outer ring having a plurality of curved ball grooves on the inner periphery, an inner ring having a plurality of curved ball grooves on the outer periphery, and a ball groove of the outer ring and a ball groove of the inner ring. And a cage for holding the ball. The outer ring ball groove center is located on the outer ring opening side with respect to the outer ring inner spherical center, and the inner ring ball groove center is located on the outer ring rear side with respect to the inner ring outer spherical center, and is offset by an equal distance in the opposite direction in the axial direction. is doing. Therefore, the ball track constituted by the ball groove of the outer ring and the ball groove of the inner ring has a wedge shape that expands toward the opening side of the outer ring. In BJ, the entire area of each ball groove is curved, but in UJ, one end of each ball groove is in a straight shape parallel to the axis.

  As shown in FIG. 8, the steering system transmits the rotational motion of the steering wheel 62 to the steering gear 66 through a steering column including one or a plurality of steering shafts 64, thereby converting the tie rod 68 into a reciprocating motion. It is what I did. If the steering shaft 64 cannot be arranged in a straight line in consideration of the vehicle-mounted space or the like, the steering gear 66 can be accurately rotated even when one or more steering joints 60 are arranged between the steering shafts 64 and the steering shaft 64 is bent. Can be communicated.

  In general, two or more cardan joints are used for an automobile steering joint. Since the cardan joint is not uniform at a single unit, the cardan joint is arranged and used so as to cancel each other's fluctuation components in order to ensure constant velocity. For this reason, there exists a problem that the design freedom of a vehicle is impaired. It is possible to increase the design freedom of the vehicle by using a constant velocity universal joint that can ensure constant velocity at an arbitrary angle as a steering joint. However, the constant velocity universal joint has a large amount of play in the rotation direction, so the vehicle goes straight ahead. There is a concern that the steering operation feeling in the vicinity may deteriorate and noise may be caused.

  The fixed constant velocity universal joint has a gap between the ball groove of the outer ring and the ball groove of the inner ring through the ball (clearance between the ball grooves) in terms of function and processing surface. There is also a clearance between the outer spherical surface and between the outer spherical surface of the inner ring and the inner spherical surface of the cage. These clearances appear as the amount of movement when either the inner ring or the outer ring is fixed in the neutral state of the joint and the other is moved in the radial direction or the axial direction. Depending on the direction of movement, the radial clearance and the axial clearance So called. These clearances greatly affect the circumferential play (rotational backlash) between the inner and outer rings, and the greater the clearance between the ball grooves, the greater the rotational backlash. For this reason, a rotation backlash exceeding a certain level is inevitable.

  In order to solve this problem, it has been proposed to eliminate the rotational backlash by reducing the clearance between the ball grooves of the fixed type constant velocity universal joint (Patent Document 1).

On the other hand, the outer rings of a pair of fixed type constant velocity universal joints are integrated, and a centering plate provided at the center of the outer ring (housing) and a pilot lever provided at the tip of each fixed type constant velocity universal joint are cooperated. It has been proposed to provide a fixed type constant velocity universal joint capable of handling high angles by configuring a centering mechanism that controls the bending angle of both fixed type constant velocity universal joints to be equal. Patent Document 2).
Japanese Patent Laid-Open No. 2003-130082 Japanese Patent Laid-Open No. 01-210619

  The proposals in Patent Document 2 are: (1) no backlashing mechanism; (2) the outer ring outer diameter increases due to the use of a centering plate; and (3) a pilot lever is provided at the end of the shaft so that the unit joint There is a problem that a large bending angle cannot be obtained.

  The main object of the present invention is to eliminate the above-mentioned problems in the prior art, and more specifically, to provide a fixed type constant velocity universal joint having a higher angle specification and less rotating backlash. It is in.

  The fixed type constant velocity universal joint of the present invention comprises a pair of fixed type constant velocity universal joints, and each fixed type constant velocity universal joint has an outer ring having a ball groove on the inner peripheral surface and a ball groove on the outer peripheral surface. The inner ring, the ball incorporated in the wedge-shaped ball track formed by the ball groove of the outer ring and the ball groove of the inner ring, a cage having a pocket for accommodating the ball, and the inner ring and the cage And a backlash mechanism for eliminating rotational backlash by axially displacing, and integrating the outer rings of the pair of fixed type constant velocity universal joints, and the pair of fixed type constant velocity universal joints A centering mechanism is provided to make the bending angles of the two substantially equal.

  According to a second aspect of the present invention, in the fixed type constant velocity universal joint according to the first aspect, the backlashing mechanism includes a pressing member provided on the inner ring side and a receiving member provided on the cage for receiving the pressing member. The inner ring is elastically pushed toward the expansion side of the ball track.

  According to a third aspect of the present invention, in the fixed type constant velocity universal joint according to the second aspect, the centering mechanism has a pilot lever provided in a cage of one fixed type constant velocity universal joint, and the other for receiving the pilot lever. And a guide member provided in the cage of the fixed type constant velocity universal joint.

  The invention of claim 4 is the fixed type constant velocity universal joint according to any one of claims 1 to 3, wherein the ball groove phase of one fixed type constant velocity universal joint and the phase between the ball grooves of the other fixed type constant velocity universal joint. Are the same.

  According to a fifth aspect of the present invention, in the fixed type constant velocity universal joint according to the fourth aspect, a deviation range between a ball groove phase of one fixed type constant velocity universal joint and a phase between the ball grooves of the other fixed type constant velocity universal joint is set. It is characterized by being ± 20 deg.

  A sixth aspect of the present invention is the fixed type constant velocity universal joint according to any one of the first to fourth aspects, wherein the fixed type constant velocity universal joint is used for coupling a steering shaft in a steering system.

  According to the present invention, the outer rings of a pair of fixed type constant velocity universal joints having a backlashing mechanism are integrated with each other, and the bending angles of the pair of fixed type constant velocity universal joints are made substantially uniform by a centering mechanism. Therefore, it is possible to provide a fixed type constant velocity universal joint having a high angle and no backlash (rotational backlash). Further, by providing the centering mechanism between the cages, the operation range (angle) per joint of the centering mechanism can be half of the conventional technology (θ / 2). Furthermore, since a centering mechanism that does not use a centering plate is adopted, it is not necessary to increase the outer diameter of the outer ring.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, the steering system will be briefly described with reference to FIG. The steering system transmits the rotational motion of the steering wheel 2 to the steering gear 6 via a steering column including a plurality of steering shafts 4. Two fixed constant velocity universal joints 8 are arranged between the steering shafts 4 so that accurate rotational motion can be transmitted to the steering gear 6 even when the steering shaft 4 is bent. The symbol α in FIG. 1A represents the bending angle of the joint, and a large angle at which the bending angle α exceeds 30 ° can be set.

  Next, the fixed type constant velocity universal joint 8 will be described. In addition, even if it is UJ and other fixed type constant velocity universal joints, it can apply similarly and has the same effect, but here demonstrates BJ as an example. In the embodiment shown in FIG. 1, one fixed type constant velocity universal joint 8 is configured by a pair of fixed type constant velocity universal joints 8A and 8B having a common outer ring. Hereinafter, the pair of fixed type constant velocity universal joints 8A and 8B may be referred to as unit joints.

  Each of the unit joints 8A and 8B includes an outer ring 10 as an outer joint member, an inner ring 20 as an inner joint member, a ball 30 as a torque transmission element, and a cage 40 as main components. The outer ring 10 is connected to the input shaft or the output shaft, and the inner ring 20 is connected to the output shaft or the input shaft. Here, the inner ring 20 is serrated with the steering shaft 4.

  The outer ring 10 is common to the pair of unit joints 8A and 8B. In other words, it has a single cylindrical shape as a whole, and includes an outer ring portion of the unit joint 8A at one end and an outer ring portion of the unit joint 8B at the other end. In each outer ring portion, ball grooves 14 extending in the axial direction are formed at equal circumferential positions of the inner spherical surface 12. In the inner ring 20, ball grooves 24 extending in the axial direction are formed at equal circumferential positions of the outer spherical surface 22. A ball 30 is incorporated between the ball groove 14 of the outer ring 10 and the ball groove 24 of the inner ring 20 that form a pair. The cage 40 is slidably interposed between the inner spherical surface 12 of the outer ring 10 and the outer spherical surface 22 of the inner ring 20, and has a plurality of pockets 46 for accommodating the balls 30 in the circumferential direction. The cage 40 holds all the balls 30 in the same plane.

  The outer spherical surface 42 of the cage 40 is in spherical contact with the inner spherical surface 12 of the outer ring 10, and the inner spherical surface 44 of the cage 40 is in spherical contact with the outer spherical surface 22 of the inner ring 20. The center of the inner spherical surface 12 of the outer ring 10 and the center of the outer spherical surface 22 of the inner ring 20 coincide with the joint center O. The center O1 of the ball groove 14 of the outer ring 10 and the center O2 of the ball groove 24 of the inner ring 20 are offset by an equal distance in the opposite directions in the axial direction. For this reason, the ball track formed by the pair of ball grooves 14 and 24 shrinks from the opening side of the outer ring 10 toward the back side, in other words, expands from the back side of the outer ring 10 toward the opening side. It has a wedge shape.

  In this fixed type constant velocity universal joint, as shown in FIG. 1, when the outer ring 10 and the inner ring 20 have an operating angle θ, the ball 30 is maintained in a plane perpendicular to the bisector of the operating angle θ. The constant velocity of the joint is ensured.

  The backlash filling mechanism 50 illustrated in FIG. 2 will be described. The backlash filling mechanism 50 includes a pressing member 52 and a receiving member 54.

  The pressing member 52 is provided at the shaft end of the steering shaft 4 and includes a pressing portion 52a, an elastic member 52b, and a case 52c. Here, a ball is illustrated as the pressing portion 52a, but other shapes having a convex spherical portion in part may be employed. Although the compression coil spring is illustrated as the elastic member 52b, any elastic member may be used as long as it can apply an elastic force in a direction protruding from the case 52c to the pressing portion 52a. The opening end of the case 52c is caulked so that the pressing portion 52a does not fall off. Accordingly, the pressing portion 52a, the elastic member 52b, and the case 52c constitute a sub-assembly capable of unit handling. The case 52c is fixed to the front end portion of the steering shaft 4 integrated with the inner ring 20 by serration coupling by appropriate means such as press fitting or adhesive.

  The receiving member 54 is attached to the end of the cage 40 on the back side of the outer ring 10. The receiving member 54 has a cap shape covering the end opening of the cage 40, and includes a partially spherical surface portion 54a and an attachment portion 54b formed in an annular shape on the outer periphery thereof. The inner surface of the spherical surface portion 54a, that is, the surface facing the steering shaft 4 is a concave spherical surface, and functions as a receiving portion that receives the pressing force from the pressing portion 52a. The attachment portion 54b is fixed to the opening end portion of the cage 40 by appropriate means such as press fitting or welding.

  To smoothly slide the pressing member 52 and the receiving member 54 when the joint takes an operating angle θ, as shown in FIG. 3, the radius Ro of the spherical portion 54a is set larger than the radius r of the pressing portion 52a. Yes (Ro> r). Further, in order to prevent the receiving member 54 and the inner ring 20 from interfering with each other when the operating angle θ is taken, the radius Ro of the spherical portion 54a is larger than the radius Ri of the outer spherical surface 22 of the inner ring 20 (Ro>). Ri).

  In the above configuration, when the serration shaft portion of the steering shaft 4 and the inner ring 20 are serration-coupled and the retaining ring is mounted and the two are completely coupled, the pressing portion 52a of the pressing member 52 and the spherical portion 54a of the receiving member 54 are combined. Are in contact with each other, and the elastic member 52b is compressed. As a result, the inner ring 20 integrated with the steering shaft 4 is axially displaced toward the opening side of the outer ring 10 due to the elastic force, and this displacement causes the inner ring to move in a direction in which the clearance between the ball and the ball groove is closed. The axial clearance of the ball groove is filled and rotation backlash is prevented.

  Next, the centering mechanism 60 will be described. In the fixed type constant velocity universal joint 8 </ b> A appearing on the left side of FIG. 1, the pilot lever 62 is fixed to the spherical surface portion 54 a of the receiving member 54. The pilot lever 62 extends coaxially with the central axis of the fixed type constant velocity universal joint 8A, and a sphere 64 is fixed to the tip. On the other hand, in the fixed type constant velocity universal joint 8 </ b> B appearing on the right side of FIG. 1, a pipe 66 is fixed to the spherical surface portion 54 a of the receiving member 54. The pipe 66 extends coaxially with the central axis of the fixed type constant velocity universal joint 8B and has a hole 68 therein. The pipe 66 slidably receives the sphere 64 of the pilot lever 62 in the hole 68 and functions as a guide member for the pilot lever 62. In this way, the centering mechanism 60 serves to make the operating angles θ of the fixed type constant velocity universal joints 8A and 8B substantially equal.

  As is apparent from FIG. 1, the operating angle of the fixed type constant velocity universal joint 8 is indicated by the symbol α, which is much higher than the operating angle θ of each unit joint 8A, 8B.

  In the fixed type constant velocity universal joint 8 described above, when the ball groove 14 of the unit joint 8A and the ball groove 14 of the unit joint 8B have the same phase, when the steering joint is attached to the vehicle, the steering shaft in the straight traveling state of the vehicle It is preferable that the four bent phases are aligned in the direction of the ball grooves 14 and 24 of the constant velocity universal joint 8. In other words, the rotational direction phase in which the bending direction of the steering shaft 4 is in the direction of the ball grooves 14 and 24 and the steering wheel rotational phase in the straight traveling state of the vehicle are matched. As a result, it is possible to avoid the deterioration of the operability associated with the increase in hysteresis.

  It is known that the hysteresis of the torque-torsion angle curve of the joint changes depending on the state of attachment to the vehicle, that is, the rotational direction phase when attached between the steering column and the steering gear (Patent Document 2). When the bending direction of the steering shaft when attached to the vehicle is the ball groove direction as shown in FIG. 4B, the hysteresis is small (FIG. 5). However, when the steering shaft is bent in the direction between the ball grooves as shown in FIG. 4C, the hysteresis becomes large (FIG. 6). Such a tendency is particularly noticeable when the set joint angle (α: FIG. 4A) is a large angle exceeding 30 °.

  Since the increase in hysteresis in the torque-torsion angle diagram of the joint affects the steering wheel operability (direct feeling) in a straight traveling state of the automobile, it is desirable that the hysteresis is small. For this reason, by adjusting the bending phase of the steering shaft in the straight traveling state of the automobile so as to be in the ball groove direction, it is possible to avoid the deterioration of the operability due to the increase in hysteresis.

  In the embodiment shown in FIG. 4, the ball groove phase of one unit joint 8A (FIG. 4B) and the phase between ball grooves of the other unit joint 8B (FIG. 4C) are made to coincide. Thus, the ball groove 14 of the outer ring 10 is processed. In this case, it is desirable that the phase shift between the ball groove phase and the phase between the ball grooves is within ± 20 ° with respect to the ball groove phase reference.

  FIG. 7 shows a backlash diagram when the steering shaft bending phase is changed every 10 ° from the ball groove direction to the ball groove direction. This is the case where the phase 0 ° (FIG. 7A) is in the ball groove direction and the phase 30 ° (FIG. 7D) is in the ball groove direction. From these, it can be seen that the change in hysteresis is slightly larger at a phase of 20 ° from the ball groove direction. Therefore, by setting the direction of the steering shaft to be ± 20 ° or less with respect to the ball groove direction reference, it is possible to avoid or mitigate the deterioration of the operability due to the increase in hysteresis.

  In addition, although the fixed type constant velocity universal joint using six balls has been described as an example, the present invention can be similarly applied to a case where many balls other than six are used.

A longitudinal sectional view of a fixed type constant velocity universal joint showing an embodiment of the present invention Enlarged view of the relevant parts of the joint of FIG. Enlarged view of the relevant parts of the joint of FIG. (A) is a schematic diagram of a steering system, (b) is a schematic diagram of a fixed constant velocity universal joint for steering, and (c) is a schematic diagram of a fixed constant velocity universal joint for steering. Torque-torsion angle diagram of the joint in FIG. Torque-torsion angle diagram of the joint in FIG. Torque-torsion angle diagram when the phase is changed every 10 ° (A) is a plan view of the steering device, (b) is a side view of the steering device, and (c) is a perspective view of the steering device.

Explanation of symbols

2 Steering wheel 4 Steering shaft 6 Steering gear 8 Fixed constant velocity universal joint 10 Outer ring (outer joint member)
12 inner spherical surface 14 ball groove 20 inner ring (inner joint member)
22 outer spherical surface 24 ball groove 30 ball (torque transmission element)
40 Cage 42 Outer sphere 44 Inner sphere 46 Pocket 50 Backlash mechanism 52 Pressing member
52a Pressing part
52b Elastic member
52c Case 54 Receiving member
54a Spherical surface
54b Mounting portion 60 Centering mechanism 62 Pilot lever 64 Spherical body 66 Pipe (guide member)
68 holes

Claims (6)

  It consists of a pair of fixed type constant velocity universal joints, and each fixed type constant velocity universal joint has an outer ring having a ball groove on the inner peripheral surface, an inner ring having a ball groove on the outer peripheral surface, and a ball groove of a pair of outer rings. And a ball built in a wedge-shaped ball track formed by a ball groove of the inner ring, a cage having a pocket for accommodating the ball, and the inner ring and the cage are relatively displaced in the axial direction to reduce the rotational backlash. A centering mechanism for integrating the outer rings of the pair of fixed type constant velocity universal joints and making the bending angles of the pair of fixed type constant velocity universal joints substantially uniform. Fixed type constant velocity universal joint with mechanism.   The play mechanism comprises a pressing member provided on the inner ring side and a receiving member provided on a cage for receiving the pressing member, and acts to elastically push the inner ring to the expansion side of the ball track. Item 1. Fixed constant velocity universal joint.   The centering mechanism includes a pilot lever provided in one fixed type constant velocity universal joint cage and a guide member provided in the other fixed type constant velocity universal joint cage for receiving the pilot lever. The fixed type constant velocity universal joint according to claim 2.   4. The fixed type constant velocity universal joint according to claim 1, wherein a ball groove phase of one fixed type constant velocity universal joint is matched with a phase between ball grooves of the other fixed type constant velocity universal joint.   5. The fixed type constant velocity universal joint according to claim 4, wherein a deviation range between the ball groove phase of one fixed type constant velocity universal joint and the phase between the ball grooves of the other fixed type constant velocity universal joint is ± 20 deg.   The fixed type constant velocity universal joint according to any one of claims 1 to 4, which is used for coupling a steering shaft in a steering system.

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