JP2006132669A - Cross groove type constant-velocity universal joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase sliding stroke without reducing the maximum operating angle. <P>SOLUTION: A cross groove type constant-velocity universal joint includes: an inner ring 10 having an outer peripheral surface with ball grooves 12, 12b formed alternately in its circumference, the ball grooves being inclined in opposite directions with each other with respect to the axis; an outer ring 20 having an inner peripheral surface with ball grooves 221, 22b formed alternately in the circumferential direction thereof, the ball grooves being inclined in opposite directions with each other with respect to the axis; torque transmission balls 30 incorporated in the intersecting portions of the ball grooves 12a, 12b of the inner ring and the ball grooves 22a, 22b of the outer ring inclined in the opposite directions with each other with respect to the axis; and cages 40 provided between the outer peripheral surface of the inner ring 10 and the inner peripheral surface of the outer ring 20 so as to retain the torque transmission balls 30 with certain intervals interposed therebetween in the circumferential direction. The angle β of inclination of the ball grooves 12a, 12b, 22a, 22b with respect to the axis is equal to or larger than 4.5° and is smaller than 8.5°. The number of the torque transmission balls 30 is eight. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a cross groove type constant velocity universal joint.

  In the cross groove type constant velocity universal joint, the ball groove of the inner ring and the ball groove of the outer ring that are paired are twisted in opposite directions with respect to the axis, and the torque transmission ball is held at the intersection of both ball grooves. ing. Because of such a structure, rattling between the torque transmitting ball and the ball groove can be reduced, and in particular, it is frequently used for propeller shafts, drive shafts and the like of automobiles that do not like rattling.

  Non-Patent Document 1 shows the most basic cross groove type constant velocity universal joint. In Non-Patent Document 1, the number of rolling elements is four or more, generally six, and the torsion angle of the ball groove with respect to the axis is the maximum operating angle of the constant velocity universal joint. The angle is designed so that the opposing ball grooves are not parallel to each other, and is generally described as 13-19 °.

  In Patent Document 1, in order to avoid a decrease in the maximum operating angle when the twist angle of the ball groove with respect to the axis is reduced, not only the ball groove is twisted with respect to the axis but also in a plane including the axis. It has been proposed to tilt.

  It is said that the cross groove type constant velocity universal joint cannot basically have a large operating angle. This is because there is an angle (limit angle) where the wedge angle formed by the ball grooves of the inner and outer rings is reversed when the joint takes an operating angle. When the operating angle of the joint exceeds the limit angle, the cage cannot maintain the balance of force and becomes unstable, and it is considered that the function of the constant velocity universal joint is lost. This phenomenon has been confirmed in the case of having six general torque transmission balls, and it is also known that the limit angle is determined by the contact angle and the twist angle of the ball groove.

In Patent Document 1, it is formulated that the limit angle can be increased by tilting the ball groove even in the plane including the axis. However, it becomes a very difficult shape in terms of manufacturing and quality control.
JP-A-5-231435 ER Wagner, “Universal Joint and Driveshaft Design Manual”, SAE, 1991, p.163-166

  In a cross-groove type constant velocity universal joint, a wedge angle (= intersection angle) is formed at the intersection between the ball groove of the inner ring and the ball groove of the outer ring, and this wedge angle causes the torque transmission ball to move into the cage pocket. Pushed to the surface. As a result, the torque transmission ball is always held at the intersection of the ball grooves, and is always maintained within the bisector of the operating angle even when an angular displacement occurs between the inner and outer rings. Thus, the cross-groove type constant velocity universal joint is excellent in that it has constant velocity and little backlash.

  However, the cross-groove type constant velocity universal joint has an operating angle compared to a constant velocity universal joint that controls the torque transmission ball by offsetting the center of the arc-shaped ball groove formed in the axial direction on the inner and outer rings. Can not be taken too large. This is because when the operating angle is increased, the wedge angle is reversed, and the balance of the force acting on the cage from the torque transmitting ball is lost. As a result, the cage becomes unstable because it cannot maintain the balance of force.

  It is conceivable to prevent the wedge angle from being reversed by increasing the twist angle of the ball grooves of the inner and outer rings. However, since the inner ring and the outer ring are alternately arranged in the circumferential direction with ball grooves twisted in opposite directions with respect to the axis, it is necessary to avoid interference between adjacent ball grooves, and there is a limit to increasing the twist angle. There is.

  The cross groove angle 2β of the cross groove type constant velocity universal joint is also related to the sliding stroke of the joint. To increase the stroke amount, it is effective to reduce the cross angle 2β of the ball groove. It becomes.

  However, if the torsion angle of the ball groove with respect to the axis is reduced in order to increase the sliding stroke of the joint, the maximum operating angle as a constant velocity universal joint is reduced. The maximum operating angle is an angle at which a maximum torque is applied when an operation of bending and returning the joint is performed in a state where the joint does not rotate. In the worst case, it does not return with an angle, that is, a catching phenomenon occurs.

  As described above, it can be seen that the cross groove type constant velocity universal joint has a small degree of freedom in the maximum operating angle and the sliding amount.

  The main object of the present invention is to increase the sliding stroke without reducing the maximum operating angle of the cross groove type constant velocity universal joint.

  The present invention relates to a cross-groove type constant velocity universal joint, an inner ring having an outer peripheral surface in which ball grooves twisted in opposite directions with respect to the axis are alternately formed in the circumferential direction, and directions opposite to each other in the axis. Torque transmission built into the intersection of the outer ring with the inner ring surface in which the ball grooves twisted in the circumferential direction are alternately formed, and the ball groove of the inner ring and the ball groove of the outer ring twisted in opposite directions with respect to the axis A ball and a cage that is interposed between the outer peripheral surface of the inner ring and the inner peripheral surface of the outer ring and holds the torque transmitting ball at a predetermined interval in the circumferential direction, and the twist angle of the ball groove with respect to the axis is 4.5 It is characterized in that the number of torque transmitting balls is 8 at a temperature of not less than ° and less than 8.5 °.

  By making the torsion angle of the ball groove with respect to the axis of the cross groove type constant velocity universal joint 4.5 ° or more and less than 8.5 ° and the number of torque transmitting balls to be 8, the maximum operating angle of the joint is not reduced, Moreover, a sliding stroke can be earned. As already mentioned, in a cross groove type constant velocity joint, there is a torque transmission ball at a certain phase, and when the operating angle is increased, the wedge angle is reversed, and the balance of the force acting on the cage from the torque transmission ball is reversed. Collapses and the drive of the cage becomes unstable. As the angle of intersection between the inner ring ball groove and the outer ring ball groove becomes smaller, this phenomenon becomes prominent when the number of torque transmitting balls is up to six. However, by using eight or more torque transmitting balls, even when the crossing angle between the ball groove of the inner ring and the ball groove of the outer ring becomes small, the drive of the cage is stabilized up to a certain value. This is because the driving force of the torque transmission ball whose wedge angle has been reversed is shared by other torque transmission balls to stabilize the driving of the cage. Table 1 described later represents this phenomenon.

  According to the present invention, even if the torsion angle of the ball groove is reduced in order to increase the sliding stroke of the cross groove type constant velocity universal joint, the maximum operating angle is not reduced because no catching occurs at the time of bending. Therefore, the sliding stroke can be increased without reducing the maximum operating angle of the cross groove type constant velocity universal joint.

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

  FIG. 2 is a longitudinal sectional view of a cross groove type constant velocity universal joint. As shown in the figure, the cross groove type constant velocity universal joint includes an inner ring 2, an outer ring 4, a torque transmission ball 6 and a cage 8 as main components.

  The inner ring 2 is ring-shaped and has ball grooves 2a and 2b formed on the outer peripheral surface. Similarly, the outer ring 4 is also ring-shaped and has ball grooves 4a and 4b formed on the inner peripheral surface. FIG. 1 is a development view of a ball groove, and as indicated by solid lines in FIG. 1, ball grooves 2a and 2b twisted in opposite directions with respect to the axis of the inner ring 2 are alternately positioned in the circumferential direction. . Further, as indicated by a two-dot chain line, ball grooves 4a and 4b twisted in opposite directions with respect to the axis of the outer ring 4 are alternately positioned in the circumferential direction.

  The twist angle of each ball groove 2a, 2b, 4a, 4b with respect to the axis is represented by the symbol β. The ball groove 2a (or ball groove 2b) of the inner ring 2 twisted in the opposite direction and the ball groove 4a (or ball groove 4b) of the outer ring 4 make a pair, and the crossing angle between them is represented by 2β.

  A torque transmitting ball 6 is incorporated at the intersection of the ball groove 2a and the ball groove 4a or the ball groove 2b and the ball groove 4b that make a pair. As shown in FIG. 3, here, there are eight ball grooves 2a, 2b of the inner ring 2, eight ball grooves 4a, 4b of the outer ring 4, and eight torque transmission balls 6.

  As shown in FIG. 4, the ball grooves 2a, 2b; 4a, 4b of the inner ring 2 and the outer ring 4 generally have a Gothic arch or elliptical cross-sectional shape, and the torque transmission ball 6 and the ball grooves 2a, 2b; , 4b is an angular contact. If the contact angle α of the angular contact is exemplified, it is in the range of 30 to 50 °.

  In order to confirm the maximum operating angle in the case of eight torque transmission balls as in the case of six torque transmitting balls, the resistance torque during the folding back operation when the bending angle is ± 10 ° was obtained by analysis. It was found that even when the twist angle β of the grooves 2a, 2b; 4a, 4b was reduced, the phenomenon of being caught until the twist angle β was 4.5 ° did not appear.

  FIG. 5 shows the torque required for the bending operation in a condition where there is no catch and a condition where the catch occurs, in which the horizontal axis represents the bending angle θ and the vertical axis represents the bending torque. As indicated by the solid torque diagram, the torque has an excessive peak at a certain bending angle in the case of the hooking condition as compared with the bending torque in the case of the non-sticking condition indicated by the broken line. Whether or not it is caught can be determined based on the presence or absence of this peak.

  Table 1 shows how far the twist angle β of the ball groove is reduced for each of the cross groove type constant velocity universal joint with six torque transmission balls and the cross groove type constant velocity universal joint with eight torque transmission balls. The results of an experiment to determine whether or not catching occurs during the folding back operation. The bending angle θ was ± 10 °. Whether or not the cross groove type constant velocity universal joint can be established is determined based on the presence or absence of the catching phenomenon. From Table 1, it was confirmed that when there are eight torque transmitting balls, the ball groove does not get caught even when the twist angle β of the ball groove is reduced to 4.5 °, that is, it is established as a cross groove type constant velocity universal joint. In the case of six torque transmitting balls, the hook angle β was 8.0 °, and the hooking occurred.

  By the way, in Patent Document 1, the limit angle is formulated by the twist angle of the ball groove. The formula is established regardless of the number of torque transmission balls. That is, the catching phenomenon should appear even if the number of torque transmitting balls increases. However, as shown in Table 1, it was confirmed that the catching phenomenon due to the wedge angle effect formed by the ball grooves of the inner and outer rings forming a pair did not occur in eight or more torque transmission balls. This is because the torque acting on the cage from the torque transmitting balls existing in a certain phase is lost by the effect that the wedge angle becomes 0 by increasing the number of torque transmitting balls. Thus, it is presumed that the constant velocity universal joint is prevented from becoming unstable.

  The cross groove constant velocity universal joint of the present invention can be used in the drive systems of automobiles, railway vehicles, and various industrial machines that require a bending angle of up to 10 °.

It is a development view of a ball groove of a cross groove type constant velocity universal joint. It is a longitudinal cross-sectional view of a cross groove type constant velocity universal joint. It is an end view of an inner ring and an outer ring of a cross groove type constant velocity universal joint. It is a principal part cross-sectional view of a cross groove type constant velocity universal joint. It is a graph which shows the relationship between a bending angle and bending torque.

Explanation of symbols

2 Inner ring 2a, 2b Ball groove 4 Outer ring 4a, 4b Ball groove 6 Torque transmission ball 8 Cage α Contact angle β Torsion angle 2β Crossing angle (wedge angle)
θ Bending angle

Claims (4)

  Inner rings having outer circumferential surfaces alternately formed in the circumferential direction with ball grooves twisted in opposite directions with respect to the axis, and ball grooves twisted in the opposite directions with respect to the axis, alternately formed in the circumferential direction. An outer ring having a peripheral surface, a torque transmitting ball incorporated at the intersection of the ball groove of the inner ring and the ball groove of the outer ring twisted in opposite directions with respect to the axis, and the outer peripheral surface of the inner ring and the inner peripheral surface of the outer ring. And a cage for holding the torque transmission balls at a predetermined interval in the circumferential direction, the twist angle of the ball groove with respect to the axis being 4.5 ° or more and less than 8.5 °, and the number of torque transmission balls being 8 is a cross groove type constant velocity universal joint.   The cross-groove type constant velocity universal joint according to claim 1, which is used in a drive system of an automobile.   The cross groove type constant velocity universal joint according to claim 1, which is used in a drive system of a railway vehicle.   The cross groove type constant velocity universal joint according to claim 1, which is used for a drive system of an industrial machine.

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