JP2007255463A - Fixed constant velocity universal joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixed constant velocity universal joint capable of reducing friction force between a cage and an outer ring generated due to a wedge angle and being easily manufactured by conventional machining technology and having excellent working property. <P>SOLUTION: A track groove 22 of an outward member comprises two kinds of track grooves, namely, a first track groove 41 and a second track groove 42. The first track groove 41 is provided with an opening side track groove 41a provided by deviating the center of curvature onto an opening side in the axial direction from the center of the joint, an innermost side track groove 41b provided by separating the center of curvature from the center of the joint in the axial direction onto an innermost side being the opposite side to the center of curvature of the opening side track groove 41a by only equal distance, and a straight groove 41c arranged between the innermost side track groove 41b and the opening side track groove 41a and having a bottom face parallel with an axial line of the outward member. The second track groove 42 is provided by deviating the center of curvature from the center of the joint onto an opening side in the axial direction. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fixed type constant velocity universal joint, and more particularly to a fixed type constant velocity joint that is used in a power transmission system of an automobile or various industrial machines and allows only angular displacement between two axes of a driving side and a driven side. It relates to a universal joint.

  For example, there is a fixed type constant velocity universal joint as a kind of constant velocity universal joint used as means for transmitting rotational force from an engine of an automobile to wheels at a constant speed. This fixed type constant velocity universal joint has a structure in which two shafts on the driving side and the driven side are connected and the rotational torque can be transmitted at a constant speed even if the two shafts have an operating angle. In general, as the above-mentioned fixed type constant velocity universal joint, a Barfield type (BJ) and an undercut free type (UJ) are widely known.

  For example, a fixed constant velocity universal joint of the BJ type has an outer ring 3 as an outer member in which a plurality of track grooves 2 are formed in the inner spherical surface 1 at equal intervals in the circumferential direction as shown in FIG. An inner ring 6 as an inner member in which a plurality of track grooves 5 paired with the track grooves 2 of the outer ring 3 are formed on the outer spherical surface 4 along the axial direction at equal intervals in the circumferential direction, and the track grooves of the outer ring 3 2 and the track groove 5 of the inner ring 6 are interposed between the plurality of balls 7 for transmitting torque and the inner spherical surface 1 of the outer ring 3 and the outer spherical surface 4 of the inner ring 6 to hold the balls 7. And a cage 8. A shaft 11 is fitted into the inner ring 6.

  In this constant velocity universal joint, the center of curvature O1 of the track groove 2 of the outer ring 3 and the center of curvature O2 of the track groove 5 of the inner ring 6 are offset in the axial direction opposite to the joint center O by an equal distance f. Yes. By providing the track offset in this way, each of the track grooves 2 and 5 is shallower from the center in the axial direction on the bottom side (back side) of the outer ring and deeper on the opening side of the outer ring. As a result, the outer ring 3 A wedge-shaped ball track is formed in which the radial interval gradually increases from the bottom side (back side) to the opening side.

  That is, in the case of the track offset, since the contact angle between the track grooves 2 and 5 and the ball 7 is not disengaged from the track grooves 2 and 5 and the joint operating angle is increased, the center of curvature O1 of the track groove 2 of the outer ring 3 is set as the opening side. The center of curvature O2 of the track groove 5 of the inner ring 6 is on the back side. For this reason, the depth of the groove on the back side of the track of the outer ring 3 becomes shallow, and if it becomes so shallow, the allowable load torque becomes small on the back side of the track. In order to solve this problem, there is a type in which the center of curvature of the track groove 2 of the outer ring 3 is set to the back side from the joint center and the center of curvature of the track groove 5 of the inner ring 5 is set to the opening side (Patent Document 1).

  By the way, in the case of the offset as shown in FIG. 8, the wedge angles α1, α2 generated by the offset are expanded toward the outer ring opening side. For this reason, when a torque is applied to the joint, as shown by the arrow in FIG. 8, a force that the ball 7 tries to jump out of the outer ring 3 acts. Therefore, the cage 8 is strongly pressed by the ball 7 toward the outer ring opening side, and a strong frictional force is generated between the cage outer diameter and the inner spherical surface 1 of the outer ring 3 to generate heat. For this reason, efficiency reduction due to heat generation (which leads to a reduction in fuel consumption in an actual vehicle) and a reduction in service life have been caused.

Therefore, there is a conventional technique in which two types of track shapes having opposite offsets are alternately combined (Patent Document 2). As a result, a force applied to the ball due to the wedge angle is generated to alternately cancel the opening side and the back side so that the cage is not pressed against one of the outer rings.
Special table 2004-518083 gazette Japanese Patent No. 3111930

  However, if the center of curvature of the track groove of the outer ring is the back side from the joint center and the center of curvature of the track groove of the inner ring is the opening side, the ball track formed by the track groove is from the back side of the outer ring to the opening side. When the operating angle is taken, the load point of the ball 7 may be removed from the ball track, so that a high operating angle cannot be obtained. Further, when considering the interference with the shaft, the track length on the opening side cannot be secured, so that a large operating angle cannot be taken.

  Therefore, in order to ensure a large operating angle, it is necessary to perform an additional process for enlarging the track groove on the opening side. In addition, in the case of alternately combining two types of track shapes in which the offsets are reversed, the additional process on the outer ring opening side is different, so that the machining process is complicated. Furthermore, there is a drawback that forging is difficult if the track shapes are alternately different.

  In view of the above problems, the present invention reduces the frictional force between the cage and the outer ring due to the wedge angle, has good operability, and can be easily manufactured by conventional processing techniques. Provide a constant velocity universal joint.

The fixed type constant velocity universal joint of the present invention includes an outer member in which a plurality of track grooves are formed on the inner spherical surface along the axial direction at equal intervals in the circumferential direction, and a plurality of track grooves on the outer spherical surface in the circumferential direction, etc. An inner member formed along the axial direction at intervals, a plurality of balls that are interposed between the track grooves of the outer member and the track grooves of the inner member, and transmit torque; and In a fixed type constant velocity universal joint provided with a cage that is interposed between an inner spherical surface and an outer spherical surface of an inner member and holds a ball,
The outer member has two types of track grooves, a first track groove and a second track groove. The first track groove is an opening-side track groove provided with the center of curvature shifted from the joint center to the opening side in the axial direction. And a back side track groove provided at an equal distance away from the center of curvature in the axial direction from the joint center on the back side opposite to the center of curvature of the open side track groove, and the back side track groove and the open side track groove, The second track groove is provided by shifting the center of curvature from the joint center toward the opening side in the axial direction.

  In the fixed type constant velocity universal joint of the present invention, when the operating angle is taken with respect to the pair of first tracks arranged in a phase of 180 degrees, the ball in one track groove is positioned on the back side as shown in FIG. The ball in the other track groove is located on the opening side. In such a case, the wedge angles are in opposite directions with respect to the two balls. For this reason, the force generated by the wedge angle, that is, the force for pushing the ball toward the wedge opening is generated in opposite directions, and the forces cancel each other. For this reason, the cage is not unilaterally pressed against the opening side of the outer ring by the ball. However, by having the straight groove, the wedge angle becomes 0 degree without taking the operating angle. Therefore, since the direction of the wedge angle is reversed when the operating angle is around 0 degrees, a region where the wedge angle becomes small is formed, and the operability is deteriorated. However, the second track groove has a wedge angle even when the operating angle is 0 degree, and the wedge angle is maintained at the same angle throughout the entire area.

  The track groove of the inner member has two types, a first track groove and a second track groove, and the first track groove is an opening side track groove provided by shifting the center of curvature from the joint center to the opening side in the axial direction. And a back side track groove provided at an equal distance away from the center of curvature in the axial direction from the joint center on the back side opposite to the center of curvature of the open side track groove, and the back side track groove and the open side track groove, The second track groove is provided by shifting the center of curvature from the joint center to the back side in the axial direction.

  Thus, since the track groove of the inner member has two types of the first track groove and the second track groove, the first track groove of the inner member and the first track of the outer member corresponding thereto are provided. The ball track constituted by the groove and the second track groove of the inner member and the corresponding second track groove of the outer member have a shape in which the ball rolls smoothly. Can do.

  At least one pair of the first track grooves is provided, and the first track grooves are opposed to each other at a phase of 180 degrees. As a result, when the operating angle is taken, the wedge angles are surely opposite to each other with respect to the two balls, and the forces generated by the wedge angles, that is, the forces trying to push the ball toward the wedge opening are mutually They occur exactly in the opposite directions and their forces cancel each other out stably.

  By providing the first track groove, the force with which the cage is pressed against the opening side of the outer ring (outer member) by the ball can be reduced. For this reason, the frictional force between the outer spherical surface of the cage and the inner spherical surface of the outer ring can be reduced, and the joint life is improved. That is, when mounted on an automobile, fuel efficiency is improved. Further, by providing the second track groove, the second track groove has a wedge angle even when the operating angle is 0 degree, and the wedge angle is maintained at the same angle in the entire region. By providing the first track groove and the second track groove having different shapes as described above, the friction force can be reduced by the first track groove and the operability can be secured by the second track groove.

  The second track groove has the same shape as the track groove of this type of fixed type constant velocity universal joint. For this reason, it is not necessary to perform processing (additional processing) for expanding the track groove so that the operating angle can be easily taken on the outer ring opening side. That is, the operability of the fixed type constant velocity universal joint can be ensured without additional processing. In addition, in the fixed type constant velocity universal joint, even if additional processing is performed on the outer ring (outer member) in order to ensure the operating angle, the track shape on the opening side is the same for both the first track and the second track. Therefore, one type of additional machining is sufficient.

  In addition, the first track groove is formed deeper than the second track groove in the entire region, and from the conventional product (forged product that is currently mass-produced), all of which is the second track groove, It can be manufactured by performing additional processing to become the first track groove with respect to half of the track grooves in all the track grooves. For this reason, a conventional existing forging die can be used, and there is an advantage in terms of cost.

  A ball track composed of a first track groove of the inner member and a corresponding first track groove of the outer member, a second track groove of the inner member, and a second track groove of the outer member corresponding thereto And a ball track configured to smoothly roll the ball. For this reason, various operating angles can be taken smoothly.

  An embodiment of a fixed type constant velocity universal joint according to the present invention will be described with reference to FIGS.

  As shown in FIG. 2, the fixed type constant velocity universal joint includes an outer ring 23 as an outer member in which a plurality of track grooves 22 are formed on the inner spherical surface 21 along the axial direction at equal intervals in the circumferential direction, and the outer spherical surface. 24, a plurality of track grooves 25 paired with the track grooves 22 of the outer ring 23 are formed along the axial direction at equal intervals in the circumferential direction, and the track grooves 22 and the inner rings 26 of the outer ring 23 are formed as inner members. A plurality of balls 27 that transmit torque by being interposed between the track grooves 25 and a cage 28 that is interposed between the inner spherical surface 21 of the outer ring 23 and the outer spherical surface 24 of the inner ring 26 and holds the balls 27. I have. The plurality of balls 27 are accommodated in pockets 29 formed in the cage 28 and arranged at equal intervals in the circumferential direction. A chamfer portion 30 is provided at the open end of the outer ring 23 to prevent the shaft 31 connected to the inner ring 26 from interfering with the outer ring 23 when the outer ring 23 and the inner ring 26 have a high operating angle. ing.

  A shaft 31 is inserted into a center hole (inner diameter hole) 32 of the inner ring 26 and is spline-fitted. By the spline fitting, torque can be transmitted between the two. The shaft 31 is prevented from coming off from the inner ring 26 by a retaining ring 33.

  As shown in FIG. 1, the track groove 22 of the outer ring 23 has a first track groove 41 and a second track groove 42. That is, the first track grooves 41 and the second track grooves 42 are alternately arranged along the circumferential direction. In consideration of the torque transmission function, the number of track grooves 22 is preferably 6 or more, and 8 is optimal. For this reason, it is preferable that the number of the first track grooves 41 is four and the number of the second track grooves 42 is four. The first track groove 41 and the second track groove 42 are positioned at a phase of 180 degrees and face each other.

  The track groove 25 of the inner ring 26 also has a first track groove 51 and a second track groove 52. In this case, the first track groove 51 corresponds to the first track groove 41 of the outer ring 23 to form a ball track with the first track grooves 41, 51, and the second track groove 52 is the second track groove 42 of the outer ring 23. Corresponding to the above, a ball track is formed by the second track grooves 42 and 52.

  As shown in FIGS. 2 to 4, the first track groove 41 includes an opening-side track groove 41 a provided by shifting the center of curvature a from the joint center O in the axial direction to the opening side of the outer ring 23 by a distance f1. b is disposed between the back side track groove 41b and the back side track groove 41a, which is provided at a distance f2 away from the joint center O in the axial direction on the back side opposite to the center of curvature a. The groove bottom surface is provided with a straight groove 41c parallel to the outer member axis L0. The distance f1 and the distance f2 are equidistant. Further, as shown in FIG. 6, the second track groove 42 is formed by shifting the center of curvature a from the joint center O in the axial direction to the opening side of the outer ring 23 by a distance f1.

  As shown in FIG. 3, the groove bottom radius Ro1 of the opening side track groove 41a of the outer ring 23 and the groove bottom radius Ro2 of the back side track groove 41b are set to be the same.

  As shown in FIGS. 2 to 4, the first track groove 51 of the inner ring 26 includes an opening-side track groove 51 a provided by shifting the center of curvature a from the joint center O in the axial direction to the opening side of the outer ring 23 by a distance f1. The center of curvature b is spaced from the joint center O in the axial direction by a distance f2 on the back side opposite to the center of curvature a, and between the back side track groove 51b and the opening side track groove 51a. The groove bottom surface is provided with a straight groove 51c parallel to the inner member axis L4. Further, as shown in FIG. 6, the second track groove 52 is formed by shifting the center of curvature b from the joint center O in the axial direction to the back side of the outer ring 23 by a distance f2.

  As shown in FIG. 3, the groove bottom radius Ri1 of the opening side track groove 51a of the inner ring 26 and the groove bottom radius Ri2 of the back side track groove 51b are set to be the same.

  As shown in FIG. 4, the track center line L of the first track groove 41 of the outer ring 23 has an arcuate portion La on the opening side with a radius R1 centered on the center of curvature a and the back side of the radius R2 centered on the center of curvature b. Arc portion Lb, and a straight portion Lc connecting the arc portion La on the opening side and the arc portion Lb on the back side. The track center line L1 of the first track groove 51 of the inner ring 26 includes an arc portion L1a on the opening side with a radius R1 centered on the center of curvature a and an arc portion L1b on the back side with a radius R2 centered on the center of curvature b. The straight arc portion L1c that connects the arc portion L1a on the opening side and the arc portion L1b on the back side. That is, the track center line L of the first track groove 41 of the outer ring 23 coincides with the track center line L1 of the first track groove 51 of the inner ring 26.

  As shown in FIG. 7, the track center line L2 of the second track groove 42 of the outer ring 23 is an arc having a radius R centered on the center of curvature a, and the track center line L3 of the second track groove 52 of the inner ring 26 is The center of curvature b is an arc having a radius R at the center.

  In the fixed type constant velocity universal joint of the present invention, as shown in FIG. 5, when the ball 27 in the first track grooves 41, 51 is positioned on the back side at an operating angle, the first track grooves 41 are arranged. , 51, the balls 27 in the other first track grooves 41, 51 that are 180 degrees out of phase with each other are positioned on the opening side. In such a case, the wedge angle α1 with respect to the back-side ball 27 expands toward the back side, and the wedge angle α2 with respect to the open-side ball 27 expands toward the opening side. That is, the wedge angles for the two balls 27 are in opposite directions. Therefore, a force in the direction of arrow A1 acts on the ball 27 on the back side, and a force in the direction of arrow A2 acts on the ball 27 on the opening side. The force in the direction of arrow A1 and the force in the direction of arrow A2 are opposite to each other, and the forces cancel each other. Therefore, the cage 28 is not unilaterally pressed against the opening side of the outer ring 23 by the pressing force from the ball 27, and the frictional force between the outer spherical surface of the cage 28 and the inner spherical surface 21 of the outer ring 23 can be reduced. The joint life is improved. That is, when mounted on an automobile, fuel efficiency is improved.

  Further, since the first track grooves 41 and 51 have the straight grooves 41c and 51c, as shown in FIG. 2, the wedge angle becomes 0 degree without taking the operating angle. Further, when the operating angle is around 0 degrees, there is a region where the wedge angle becomes smaller because the direction of the wedge angle is reversed. For this reason, it can be said that the first track groove 41 has poor operability. However, the second track groove 42 has a wedge angle even when the operating angle is 0 degree, and the wedge angle is maintained at the same angle throughout the entire area.

  For this reason, by providing the first track grooves 41 and 51 and the second track grooves 42 and 52 having different shapes as described above, the friction force is reduced in the first track grooves 41 and 51, and the second track grooves 42. , 52 to ensure operability.

  The second track grooves 42 and 52 have the same shape as the track grooves of this type of conventional fixed type constant velocity universal joint. For this reason, it is not necessary to perform processing (additional processing) to widen the track grooves 22 and 25 on the outer ring opening side so that an operating angle can be easily obtained. That is, the operability of the fixed type constant velocity universal joint can be ensured without additional processing. In addition, in the fixed type constant velocity universal joint, even if additional processing for ensuring the operating angle is performed, only the opening side of the first track groove 41 of the outer ring 23 and the back side portion of the first track groove 51 of the inner ring 26 corresponding thereto are used. Well, the additional work of the second track can be omitted.

  Further, the first track grooves 41 and 51 are formed deeper than the second track grooves 42 and 52 in the entire region, and all of the first track grooves 41 and 51 are the second track grooves 42 and 52. The first track grooves 41 and 51 may be processed for half of all the track grooves. For this reason, a conventional existing forging die can be used, and there is an advantage in terms of cost.

  A ball track composed of the first track groove 51 of the inner ring 26 and the first track groove 41 of the outer ring 23 corresponding thereto, and the second track groove 52 of the inner ring 26 and the second track groove 42 of the outer ring 23 corresponding thereto. And a ball track configured to smoothly roll the ball. For this reason, various operating angles can be taken smoothly.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made. For example, the first track grooves 41, 51 and the second track grooves 42, 52 are possible. May be different. That is, at least a pair of the first track grooves 41 and 51 is sufficient. The range of the opening-side track grooves 41a, 51a and the back-side track grooves 41b, 51b of the first track grooves 41, 51 is in a direction in which the wedge angles with respect to the ball 27 are opposite to each other, and their forces can cancel each other. As long as the ball 27 can be arbitrarily changed and the range of the straight grooves 41c and 51c is such that the ball 27 rolls smoothly through the straight grooves 41c and 51c.

It is a front view of the fixed type constant velocity universal joint which shows embodiment of this invention. FIG. 2 is a sectional view taken along line YY in FIG. 1. It is an expanded sectional view of the 1st track groove of the above-mentioned fixed type constant velocity universal joint. It is explanatory drawing of the track centerline of the 1st track groove of the said fixed type constant velocity universal joint. FIG. 2 is a cross-sectional view taken along line YY of FIG. 1 in a state where an operating angle of the fixed type constant velocity universal joint is taken. It is an expanded sectional view which shows the 2nd track groove of the said fixed type constant velocity universal joint (XX sectional drawing of the said FIG. 1). It is explanatory drawing of the track centerline of the 2nd track groove of the said fixed type constant velocity universal joint. It is sectional drawing of the state which took the operating angle in the conventional fixed type constant velocity universal joint.

Explanation of symbols

22, 25 Track groove 24 Outer spherical surface 27 Ball 28 Cage 41 Track groove 41b Back side track groove 41a Open side track groove 41c Straight groove 42 Track groove 51, 52 Track groove 51b Back side track groove 51a Open side track groove 51c Straight groove

Claims (3)

An outer member in which a plurality of track grooves are formed in the inner spherical surface along the axial direction at equal intervals in the circumferential direction, and an inner member in which the plurality of track grooves are formed in the outer spherical surface at equal intervals in the circumferential direction along the axial direction. An outer member, a plurality of balls that are interposed between the outer member track groove and the inner member track groove to transmit torque, and an inner spherical surface of the outer member and an outer spherical surface of the inner member In a fixed type constant velocity universal joint provided with a cage for holding a ball interposed therebetween,
The outer member has two types of track grooves, a first track groove and a second track groove. The first track groove is an opening-side track groove provided with the center of curvature shifted from the joint center to the opening side in the axial direction. And a back side track groove provided at an equal distance away from the center of curvature in the axial direction from the joint center on the back side opposite to the center of curvature of the open side track groove, and the back side track groove and the open side track groove, The groove bottom surface is provided with a straight groove parallel to the outer member axis, and the second track groove is provided by shifting the center of curvature from the joint center to the opening side in the axial direction. Fixed constant velocity universal joint.   The track groove of the inner member has two types, a first track groove and a second track groove, and the first track groove is an opening side track groove provided by shifting the center of curvature from the joint center to the opening side in the axial direction. And a back side track groove provided at an equal distance away from the center of curvature in the axial direction from the joint center on the back side opposite to the center of curvature of the open side track groove, and the back side track groove and the open side track groove, The groove bottom surface is provided with a straight groove parallel to the inner member axis, and the second track groove is provided by shifting the center of curvature from the joint center to the back side in the axial direction. The fixed type constant velocity universal joint according to claim 1.   The fixed type constant velocity universal joint according to claim 1 or 2, wherein at least one pair of the first track grooves is provided and the first track grooves are opposed to each other at a phase of 180 degrees.

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