JP6287877B2 - Constant velocity joint - Google Patents

Description

  The present invention relates to an improvement in a constant velocity joint including an outer race, an inner race, and a ball.

  It has the function of transmitting rotation by connecting the input shaft (drive shaft) and the output shaft (driven shaft) where the axes intersect, and bending of the drive shaft and driven shaft as a kind of joint used in vehicles etc. A constant velocity joint that transmits rotation at a constant angular velocity between a drive shaft and a driven shaft while allowing a change in angle (joint angle) is well known. For example, the constant velocity universal joint described in Patent Document 1 is that. One form of this constant velocity joint includes an outer race and an inner race each having a plurality of ball grooves extending in the rotation axis direction, a ball fitted in the ball groove so as to be capable of rolling, and the ball. A constant velocity joint including a holding cage, and torque from the drive shaft side is transmitted to the driven shaft side via a plurality of balls. In such a constant velocity joint, regardless of the joint angle, the distance between the center of curvature of the ball groove of the outer race and the center locus of the ball rolling along the ball groove and the center of curvature of the ball groove of the inner race It has been proposed to set (design) the difference between the point and the distance between the center locus of the ball rolling along the ball groove to be constant.

JP 2001-153149 A

  By the way, when the inner race rotates at a large angle with respect to the outer race (i.e., when the joint angle is a large angle), the ball raceway of the outer race is compared with the case where the joint angle is a small angle or a medium angle. It was found that the gap between the inner race and the ball groove increased. When this interval is large, the ball easily moves in the ball groove. Therefore, there is a possibility that the load due to the ball on the ball groove or the cage becomes large. Further, the ball can easily ride on the edge of the ball groove, and the load from the ball may be concentrated on the edge of the ball groove. If the strength is increased by increasing the thickness of the cage with respect to the load from the ball at such a large angle, it may be difficult to reduce the size of the constant velocity joint. Note that the above-described problems are not known, and no proposal has been made yet to reduce the load caused by the ball when the joint angle becomes a large angle in order to ensure the miniaturization and strength of the constant velocity joint.

  The present invention has been made against the background of the above circumstances, and an object of the present invention is to provide a constant velocity joint capable of reducing a load caused by a ball when the joint angle becomes a large angle. is there.

  The gist of the first invention for achieving the above object is as follows: (a) an outer race in which ball grooves extending in the rotational axis direction are formed on a spherical inner peripheral surface at predetermined intervals in the circumferential direction; An inner race in which a ball groove extending in the direction of the rotation axis and paired with a ball groove of the outer race is formed on a spherical outer peripheral surface; and a ball groove of the outer race and a ball groove of the inner race A constant velocity joint comprising a ball fitted in a space along the ball groove in a space therebetween, and (b) a center point of curvature of the outer race ball groove and a ball groove of the outer race The distance from the trajectory passing through the center of the ball rolling along the center, the center of curvature of the ball groove of the inner race and the trajectory passing through the center of the ball rolling along the ball groove of the inner race The difference between the distances is that towards the rotation axis direction of the ends region of the rotation axis direction said ball grooves than the central region of the ball groove is small.

  In this way, when the ball is located in both end regions of the ball groove in the rotational axis direction, the ball groove of the outer race is compared to when the ball is located in the central region of the ball groove in the rotational axis direction. Since an increase in the distance between the inner race and the ball groove is suppressed or avoided, the movable area of the ball in the ball groove is limited. Thereby, the load by the ball | bowl to a ball groove is reduced. Further, it is difficult for the ball to ride on the edge of the ball groove. Therefore, in the constant velocity joint of the present invention, it is possible to reduce the load caused by the ball when the joint angle becomes a large angle. In any region of the ball groove in the rotational axis direction, when the difference between the distance in the outer race and the distance in the inner race is reduced, the ball is positioned in the central region of the ball groove in the rotational axis direction. In this case, a large force always acts on the outer race and the inner race from the ball, and it may be necessary to increase the strength of the constant velocity joint. Therefore, the difference between the distance in the outer race and the distance in the inner race is reduced only in both end regions of the ball groove in the rotational axis direction.

It is a figure explaining schematic structure of the constant velocity joint to which the present invention is applied, and is a partial sectional view which looked at the outer race from the direction perpendicular to the axis of rotation. It is a figure explaining schematic structure of the constant velocity joint to which the present invention is applied, and is a partial sectional view which looked at the inner race from the direction perpendicular to the axis of rotation. It is a figure which shows an example of the setting value of PCR clearance of a present Example. It is a figure for demonstrating the subject in a comparative example.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram illustrating a schematic configuration of a constant velocity joint 10 to which the present invention is applied, and is a partial cross-sectional view of an outer race 12 viewed from a direction perpendicular to a rotation axis Cout. FIG. 2 is a diagram illustrating a schematic configuration of the constant velocity joint 10 to which the present invention is applied, and is a partial cross-sectional view of the inner race 14 viewed from a direction perpendicular to the rotation axis Cin. 1 and 2, the rotation axis Cout of the outer race 12 is a rotation axis of an output shaft (not shown) formed integrally with the outer race 12. A rotation axis Cin of the inner race 14 is a rotation axis of an input shaft (not shown) that is rotated integrally with the inner race 14. The input shaft and the output shaft are connected via a constant velocity joint 10 so as to be relatively unrotatable around the rotation axes Cout and Cin and relatively rotatable in a plane including the rotation axes Cout and Cin. Yes. That is, the rotational force from the input shaft is within a predetermined range in which a change in joint angle, which is an axial bending angle (angle formed by the rotational axis Cin and the rotational axis Cout) between the input shaft and the output shaft, is allowed. In FIG. 2, the signal is transmitted to the output shaft side at a constant angular velocity. The constant velocity joint 10 is preferably for a vehicle. In a vehicle, the input shaft is, for example, an axle, and is connected to an engine via a differential gear, a transmission, or the like, and the output shaft is connected to, for example, driving wheels (for example, front wheels of FF vehicles or 4WD vehicles). Is done.

  The constant velocity joint 10 includes an outer race 12 that is an outer joint member, an inner race 14 that is an inner joint member, and a plurality of balls 16 that are torque transmission members interposed between the outer race 12 and the inner race 14. And an annular cage (not shown), which is a cage for holding the plurality of balls 16 so as to be able to roll.

  The outer race 12 is formed in a groove shape with an opening 18 provided at one end, a spherical inner peripheral surface 20, and a predetermined interval in the circumferential direction and extending in the rotational axis Cout direction on the inner peripheral surface 20. The ball groove 22 is provided. The inner race 14 has a spherical outer peripheral surface 24 and a groove shape in which the outer race 24 extends in the circumferential direction at a predetermined interval and in the rotational axis Cin direction and forms a pair with the ball groove 22 of the outer race 12. And a formed ball groove 26. The ball 16 is fitted in a space between the ball groove 22 of the outer race 12 and the ball groove 26 of the inner race 14 so as to roll along the ball grooves 22 and 26. The cage includes a spherical outer peripheral surface that is entirely in sliding contact with the inner peripheral surface 20 of the outer race 12, a spherical inner peripheral surface that is generally in sliding contact with the outer peripheral surface 24 of the inner race 14, and a plurality of balls 16. And a plurality of window portions provided so as to penetrate at a predetermined interval in the circumferential direction.

  The center of curvature Oout of the arc-shaped portion of the ball groove 22 of the outer race 12 and the center of curvature Oin of the arc-shaped portion of the ball groove 26 of the inner race 14 are the inner peripheral surface 20 and the inner race 14 of the outer race 12, respectively. Are shifted from the common center of curvature of the outer peripheral surface 24 by a predetermined distance along the rotational axes Cout and Cin. The curvature center points Oout and Oin and the common curvature center point are determined so that the ball 16 is held on the same plane that bisects the complementary angle of the joint angle by the cage.

  The distance between the curvature center point Oout and the locus Lout passing through the center of the ball 16 rolling along the ball groove 22 of the outer race 12 in the arc-shaped portion of the ball groove 22 of the outer race 12, and the ball groove of the outer race 12 The distance between the rotational axis Cout and the locus Lout in the substantially linear portion 22 is referred to as a radius of curvature of the ball groove 22 of the outer race 12 (hereinafter, outer PCR). Further, in the arc-shaped portion of the ball groove 26 of the inner race 14, the distance between the center of curvature Oin and the locus Lin passing through the center of the ball 16 rolling along the ball groove 26 of the inner race 14, and the inner race 14 The distance between the rotational axis Cin and the locus Lin in the substantially linear portion of the ball groove 26 is referred to as the radius of curvature of the ball groove 26 of the inner race 14 (hereinafter referred to as inner PCR). The inner PCR is designed to be smaller than the outer PCR by a predetermined value in order to allow a smooth rolling (movement) of the ball 16. That is, the ball 16 is disposed between the ball groove 22 of the outer race 12 and the ball groove 26 of the inner race 14 with a slight clearance (gap) in the radial direction. Such a clearance, that is, a difference between the outer PCR and the inner PCR is referred to as PCR clearance (= outer PCR-inner PCR).

  The constant velocity joint 10 thus configured slides between the outer peripheral surface of the cage and the inner peripheral surface 20 of the outer race 12, and the inner peripheral surface of the cage and the outer peripheral surface 24 of the inner race 14 slide. The joint angle can be changed by moving. In the constant velocity joint 10, the plurality of balls 16 are held on the same plane by the cage, so that the constant velocity between the input shaft and the output shaft is maintained. That is, the constant velocity joint 10 can transmit a constant angular velocity power from the input shaft to the output shaft via the plurality of balls 16 while allowing a change in joint angle.

  Here, a comparative example with respect to the present embodiment will be described. In this comparative example, the PCR clearance is set to be constant regardless of the joint angle range (that is, the set value of the PCR clearance is designed to be constant). In FIGS. 1 and 2, the broken lines in the loci Lout and Lin indicate comparative examples when the set value of the PCR clearance is a constant value. 1 and 2, the position of the ball 16 is an example when the joint angle is the maximum that can be taken. With respect to the position of the ball 16 corresponding to a joint angle of 0 degrees, the opening 18 side of the outer race 12 is referred to as the mouth side, and the side opposite to the opening 18 is referred to as the back side. The position of the ball 16 on the mouth side in FIGS. 1 and 2 is the position when a certain ball 16 is located on the most mouth side, and this position is the rotational phase 0 [deg] or 360 around the rotation axes Cout and Cin. [deg].

  By the way, in the comparative example, when the joint angle is in the large angle region, the ball groove 22 of the outer race 12 and the ball groove 26 of the inner race 14 are compared with the case where the joint angle is in the small angle region or the medium angle region. It has been found that the interval (hereinafter referred to as groove clearance) increases. When the groove clearance is large, the ball 16 can easily move in the ball grooves 22 and 26. Then, when the joint angle is in the large angle region, in the region near the rotational phase 0 [deg] or 360 [deg] or the region near the rotational phase 180 [deg] (that is, the position of the ball 16 is most near the mouth side or The ball groove, which is a region near the corresponding position when the position of the ball 16 is a joint angle of 0 degrees (at both end regions in the rotation axis Cout, Cin direction of the ball grooves 22, 26, which is a region near the back side) There is a possibility that the load applied by the ball 16 to the ball grooves 22 and 26 and the cage may be larger than the central regions of the rotational axes Cout and Cin of the pins 22 and 26 (see FIG. 4A). Further, in the vicinity of the rotational phase 180 [deg], the possible amount of the ball 16 that can ride on the edges of the ball grooves 22 and 26 (that is, the edge riding angle; see FIG. 4B) becomes large (see FIG. 4C). The load from the ball 16 may be concentrated on the edges of the ball grooves 22 and 26. It is possible to increase the strength by increasing the thickness of the cage with respect to the load caused by the ball 16 when the joint angle is in the large angle region. On the other hand, it may be difficult to reduce the size of the constant velocity joint 10. In the present embodiment, in order to ensure the miniaturization and strength of the constant velocity joint 10, it is proposed to reduce the load applied by the ball 16 when the joint angle is in the large angle region.

  In the present embodiment, the PCR clearance of the constant velocity joint 10 is larger in the regions of both end regions of the ball grooves 22 and 26 in the rotation axis Cout and Cin directions than in the central region of the ball grooves 22 and 26 in the rotation axis Cout and Cin direction. Is smaller. That is, the PCR clearance when the joint angle is in the large angle region is set smaller than that in the normal angle region such as the small angle region or the medium angle region.

  FIG. 3 is a diagram illustrating an example of a set value of the PCR clearance that realizes the present embodiment. In FIG. 3, the PCR clearance set value is a constant value (predetermined value) in a region in the vicinity of the position corresponding to the position of the ball 16 having a joint angle of 0 degrees. Further, in the region where the position of the ball 16 is closest to the mouth side or the back side, the set value of the PCR clearance is a value that is gradually reduced from the predetermined value as it becomes the mouth side or the back side. As a method for reducing the PCR clearance, the inner PCR is set to be large as shown by the solid line in the locus Lin in FIG. 2 in the region where the ball 16 is closest to the mouth side or the back side. There is a method of setting the outer PCR small as shown by a solid line in the locus Lout. Therefore, in this embodiment, only the inner PCR is set large, only the outer PCR is set small, or the inner PCR is set large and the outer PCR is set small, thereby reducing the PCR clearance. .

  It should be noted that the setting value of the PCR clearance in any of the regions of the ball grooves 22 and 26 in the rotational axis Cout and Cin directions mainly considering appropriate groove clearance when the joint angle is in the large angle region. It is conceivable to reduce the size. However, with this setting, when the ball 16 is located in the central region of the ball grooves 22 and 26 in the direction of the rotation axis Cout or Cin, a large force can always be applied from the ball 16 to the outer race 12 and the inner race 14. There is sex. If it does so, the intensity | strength increase of the constant velocity joint 10 with respect to this may be needed. Therefore, in this embodiment, the PCR clearance is reduced only in the both end regions of the ball grooves 22 and 26 in the directions of the rotational axes Cout and Cin.

  As described above, according to the present embodiment, the PCR clearance of the constant velocity joint 10 is greater than the central region of the ball grooves 22 and 26 in the direction of the rotation axis Cout and Cin, and the rotation axis Cout of the ball grooves 22 and 26. , Cin direction end regions are smaller, so that when the ball 16 is positioned at the rotation axis Cout of the ball grooves 22, 26, the ball 16 is the rotation axis of the ball grooves 22, 26. Compared with the case of being located in the central region in the Cout and Cin directions, an increase in the groove clearance is suppressed or avoided, and the movable region of the ball 16 in the ball grooves 22 and 26 is limited. Thereby, the load by the ball | bowl 16 to the ball grooves 22 and 26 is reduced. Further, it is difficult for the ball 16 to ride on the edges of the ball grooves 22 and 26. Therefore, in the constant velocity joint 10 of the present embodiment, the load caused by the ball 16 when the joint angle becomes a large angle can be reduced.

  As mentioned above, although the Example of this invention was described in detail based on drawing, this invention is applied also in another aspect.

  For example, in the above-described embodiment, the fixed type constant velocity joint 10 is exemplified as the constant velocity joint, but the present invention is not limited thereto. The point is that the present invention can be applied to any constant velocity joint in which a plurality of balls are arranged in the space between the outer race and the inner race and power can be transmitted through the balls.

  The above description is only an embodiment, and the present invention can be implemented in variously modified and improved forms based on the knowledge of those skilled in the art.

10: constant velocity joint 12: outer race 14: inner race 16: ball 20: inner peripheral surface 22: outer race ball groove 24: outer peripheral surface 26: inner race ball groove Cin: inner race rotational axis Cout: outer Race rotation axis Lin: Trajectory through the center of the ball in the inner race Lout: Trajectory through the center of the ball in the outer race Oin: Center of curvature of the ball groove of the inner race Oout: Center of curvature of the ball groove of the outer race

Claims (1)

An outer race in which ball grooves extending in the rotation axis direction are formed on a spherical inner peripheral surface at predetermined intervals in the circumferential direction, and a ball groove extending in the rotation axis direction and paired with the ball grooves of the outer race, respectively. An inner race formed on a spherical outer peripheral surface, and a ball fitted in a space between the ball groove of the outer race and the ball groove of the inner race so as to roll along the ball groove. A constant velocity joint
The distance between the center of curvature of the ball groove of the outer race and the trajectory passing through the center of the ball rolling along the ball groove of the outer race, the center of curvature of the ball groove of the inner race and the center of the inner race The difference from the distance from the trajectory passing through the center of the ball that rolls along the ball groove is greater than the center region of the ball groove in the rotational axis direction than the center region of the ball groove in the rotational axis direction. Constant velocity joint characterized by being smaller.

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