JP2004332817A - Fixed type constant speed universal joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixed type constant speed universal joint which is higher in strength and bending angle than a known fixed type constant speed universal joint at lower cost. <P>SOLUTION: A bottom of a track groove 14 of an outer ring 10 is constituted of an arcuate part 14a which is located on the depth side of the outer ring 10 along the meridian of a sphere with a center O of a joint as a center thereof, and a straight part 14b which is located on an opening side of the outer ring 10 and expanded straight toward an opening end part of the outer ring 10. A bottom of a track groove 24 of an inner ring 20 is constituted of an arcuate part 24a which is located on the opening side of the outer ring 10 along the meridian of a sphere with the center O of a joint as a center thereof, and a straight part 24b which is expanded straight toward the depth side of the outer ring 10. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fixed type constant velocity universal joint that does not perform plunging, and can be used for power transmission in automobiles and various industrial machines.
[0002]
[Prior art]
Conventionally, as a fixed type constant velocity universal joint, a ball joint of a Zeppa type and a UF (undercut free) type are known (see Japanese Patent Publication No. 6-25567). Their feature is that the outer groove track groove and the inner ring track groove are respectively formed along meridians of the sphere centered at points equidistant in the axial direction from the bending point of the joint. As shown in FIGS. 5 to 7, the conventional fixed type constant velocity universal joint has an outer ring 1, an inner ring 2, a cage 3, and a ball 4 as main components, and a track groove 1a of the outer ring 1 and an inner ring. The balls 4 are used one by one between the two track grooves 2a. As can be seen from FIG. 5, the center of curvature Oo of the track groove 1a of the outer race 1 and the center of curvature Oi of the track groove 2a of the inner race 2 are offset in opposite directions in the axial direction with respect to the joint bending point, that is, the joint center O. ing. As a result, the depth of the track grooves 1a, 2a in both the outer ring 1 and the inner ring 2 changes in the axial direction.
[0003]
FIG. 5 shows a state in which the outer ring 1 and the inner ring 2 are coaxial, that is, a state in which the bending angle is 0 degree, and FIG. 7 shows a state in which the bending angle θ is the maximum. Thus, the angle θ between the axis of the outer ring 1 and the axis of the inner ring 2 is called the bending angle or the operating angle of the joint. When the joint takes a certain bending angle θ, a plane perpendicular to the bisector of the angle θ is referred to as a joint plane P. When the joint takes a bending angle, if all the balls are on the joint plane P, the distance from the ball center to the axis of the outer ring 1 and the distance from the ball center to the axis of the inner ring 2 are equal. Torque is transmitted between the outer wheels at a constant angular speed. The intersection between the joint plane P and the axes of the inner and outer rings is referred to as the joint center O. In the fixed type constant velocity universal joint, the center O of the joint is fixed regardless of the bending angle.
[0004]
As an improvement of the above constant velocity universal joint, the one described in JP-A-2001-153149 is known. The feature is that in the conventional UF type joint, an undercut free portion is provided on the inner ring and the outer ring in parallel to the shaft, but the undercut free portion has a tapered shape inclined with respect to the shaft. 8 and 9 show a constant velocity universal joint disclosed in JP-A-2001-153149. The depth of the track groove 1a of the outer ring 1 and the depth of the track groove 2a of the inner ring 2 change in the axial direction. In particular, in the track groove 1a of the outer ring 1, the depth gradually increases from the opening side of the outer ring 1 toward the back side. It turns out that it is shallow.
[0005]
[Patent Document 1]
Japanese Patent Publication No. 6-25567 (FIGS. 1 and 4)
[0006]
[Patent Document 2]
JP 2001-153149 A (paragraphs 0025 and 0026, FIG. 1)
[0007]
[Problems to be solved by the invention]
The track grooves of the outer race and the inner race of the conventional fixed-type constant velocity universal joint of the Zeppa type or the UF type vary in depth in the axial direction of the joint. There are the following problems in improving the strength or torque load capacity of the joint and further reducing the size. As shown in FIG. 10, the track grooves 1a and 2a generally hold the ball 4 in an angular manner (angular contact), but the larger the contact angle α, the higher the torque load capability. However, the magnitude of the contact angle α is determined by the shallowest part of the track grooves 1a and 2a, and the torque load capability is determined by the track depth at that position. In other words, in consideration of the riding strength when receiving the torque, a strength measure corresponding to the weakest part is required, so that parts other than the weakest part are wasteful in design.
[0008]
The constant velocity universal joint disclosed in Japanese Patent Application Laid-Open No. 2001-153149 is designed to further increase the maximum bending angle of the above-mentioned Zeppa-type or UF-type fixed constant-velocity universal joint. Have the same problems as above.
[0009]
An object of the present invention is to realize a fixed-side constant velocity universal joint having higher strength, a higher bending angle, and lower cost than conventional fixed type constant velocity universal joints.
[0010]
[Means for Solving the Problems]
The fixed type constant velocity universal joint according to the present invention includes an outer ring 10 having a plurality of track grooves 14 for guiding the ball 40, an inner ring 20 having a plurality of track grooves 24 for guiding the ball 40, and a track groove of the outer ring 10. And a plurality of balls 40 interposed between the outer ring 10 and the inner ring 20 to divide the plurality of balls 40 between the outer ring 10 and the inner ring 20 into two bisectors of the bending angle of the joint. In the constant velocity universal joint composed of the cage 30 disposed in
The groove bottom of the track groove 14 of the outer race 10 is located on the inner side of the outer race 10 and along the meridian of the sphere centered on the bending point O of the joint. A straight portion 14b having a diameter that is linearly increased toward the opening end,
The groove bottom of the track groove 24 of the inner race 20 is located on the opening side of the outer race 10, and has an arc portion 24 a along the meridian of the sphere centered on the bending point O of the joint, and linearly toward the inner side of the outer race 10. And a straight portion 24b having an enlarged diameter.
[0011]
By making the arc portions 14a, 24a of the track grooves 14, 24 of the outer ring 10 and the inner ring 20 arcs along the meridian of the sphere centered on the bending point O of the joint, the arc portions 14a, 24a of the track grooves become A certain depth is secured, and the lower limit of the torque load capacity of the joint can be raised. The shaft corresponding to the joint having the increased torque load capacity has to be large in diameter, and the bending angle is accordingly reduced. However, this reduction can be compensated for by increasing the diameter of the track groove 14 of the outer race 10 toward the opening side.
[0012]
According to the present invention, the depth of the track groove 14a of the outer ring 10 on the inner side of the outer ring 10 and the depth of the track groove 24a of the inner ring 20 on the opening side of the outer ring 10 can be made constant without becoming shallow. Is large, the contact point does not run over, which is advantageous in terms of strength. In addition, since the depth of the track groove is constant, the pitch circle diameter PCD of the ball can be reduced, and the outer diameter of the outer ring 10 can be reduced, so that the cost can be reduced. When the PCD of the outer ring 10 is reduced, the maximum bending angle of the joint is reduced. This can be compensated for by increasing the diameter of the track groove 14 of the outer ring 10 toward the opening side.
[0013]
By using seven tracks, it is possible to increase the ball diameter while securing the width of the window post as compared with eight tracks, which is advantageous in terms of strength and torque load capacity. The conventional fixed type constant velocity universal joint has 3, 6, or 8 tracks, and the number of tracks of the inboard-side joint is usually 3, 6, or 8. Therefore, phase matching is required from the viewpoint of NVH problem. And However, since the number of tracks is seven, the number of tracks is relatively prime to the number of tracks of the joint on the inboard side, so that phase matching is not required, which is advantageous in NVH characteristics.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0015]
First, FIGS. 1 and 2 show an embodiment having eight track grooves. The fixed type constant velocity universal joint includes an outer ring 10, an inner ring 20, a cage 30, and a ball 40 as main components, and connects one of the two shafts to be connected to the outer ring 10 and the other. Is connected to the inner ring 20 so that the two axes can be bent. The bending point of the joint, that is, the center of the joint is indicated by reference numeral O in FIGS.
[0016]
As shown in FIG. 1, the outer ring 10 has a cup-like shape opened at one end and has a partially spherical inner peripheral surface 12. Eight track grooves 14 running in the axial direction are formed on the inner peripheral surface 12 of the outer race 10 at equal intervals in the circumferential direction. Each track groove 14 includes an arc portion 14a located on the side opposite to the opening of the outer race 10, that is, the back side, and a straight portion 14b located on the opening side. In the case of this embodiment, as can be clearly understood from FIG. 3, the boundary between the arc portion 14a and the straight portion 14b is defined by a line segment forming an angle β on the far side of the outer ring 10 with respect to the joint plane P and the groove bottom. It is at the intersection p. The center of curvature of the arc portion 14a coincides with the joint center O. In other words, the arc portion 14a is an arc along the meridian of the sphere centered on the bending point O of the joint and located on the back side of the outer ring 10. The straight portion 14b is formed at an angle that is perpendicular to the line segment. Therefore, the degree of the diameter expansion of the straight portion 14b is determined by the magnitude of the angle β. If a specific example of the angle β is given, 0 <β <10 ° is desirable. If β is 10 ° or more, the degree of diameter expansion becomes too large, and the disadvantage of having to increase the outer diameter of the outer ring becomes significant.
[0017]
The inner race 20 is here separably connected by a shaft 5 and a spline. The inner race 20 has a partially spherical outer peripheral surface 22 on which eight track grooves 24 running in the axial direction are formed at equal intervals in the circumferential direction. Each track groove 24 includes an arc portion 24a located on the opening side of the outer ring 10 and a straight portion 24b located on the side opposite to the opening of the outer ring. In the case of this embodiment, as can be clearly understood from FIG. 3, the boundary between the arc portion 24a and the straight portion 24b is defined by the line segment forming an angle β on the opening side of the outer ring 10 with respect to the joint plane P and the groove bottom. It is at the intersection q. The center of curvature of the arc portion 24a coincides with the joint center O. In other words, the arc portion 24a is an arc along the meridian of a sphere centered on the bending point O of the joint and located on the opening side of the outer race 10. The straight portion 24b is formed at an angle that is perpendicular to the line segment. Therefore, the degree of the diameter expansion of the straight portion 24b is determined by the magnitude of the angle β. Here, the range of the angle β is determined corresponding to the outer ring, and as described above, 0 <β <10 ° is desirable if a specific example is given.
[0018]
The track groove 14 of the outer race 10 and the track groove 24 of the inner race 20 form a pair, and one ball 40 is incorporated in each pair. The ball 40 acts between the track grooves 14 and 24 to transmit torque. That is, the torque is transmitted from the outer race 10 to the inner race 20 or from the inner race 20 to the outer race 10 depending on the rotation direction. Each ball 40 is accommodated in a pocket 36 of the retainer 30. The cage 30 has a partially spherical outer peripheral surface 32, a partially spherical inner peripheral surface 34, and a plurality of pockets 36 equally spaced in the circumferential direction. The cage 30 has a role of interposing the ball 40 between the inner peripheral surface 12 of the outer race 10 and the outer peripheral surface 22 of the inner race 20 to arrange the ball 40 on the bisecting surface of the joint.
[0019]
Next, in the embodiment shown in FIGS. 3 and 4, the number of track grooves 14 and 24 is set to seven and the number of balls 40 is set to seven. There is no difference from the form. In this embodiment, by using the seven track grooves 14 and 24, the width of the window post of the cage 30 can be increased while the size of the ball 40 is increased while the thickness of the cage 30 is maintained. In other words, it is possible to maintain a balance between torque load capacity and cage strength.
[0020]
【The invention's effect】
As described above, the track groove generally holds the ball in an angular manner, and the larger the contact angle, the higher the torque load capability. However, when the track depth is non-uniform, the magnitude of the contact angle is determined by the shallowest part of the track, and wastes design compared to the case where the depth is uniform. According to the present invention, since the track depths on the opening side of the inner ring and the rear side of the outer ring can be made constant without becoming shallow, the contact point does not run on even if the bending angle is large, which is advantageous in terms of strength. . Further, since the pitch circle diameter PCD can be reduced, the outer diameter of the outer ring can be reduced to reduce the cost. When the pitch circle diameter PCD is reduced, the maximum bending angle of the joint decreases. However, this can be compensated for by increasing the diameter of the track groove of the outer ring toward the opening side.
[0021]
When the number of tracks is seven, the ball diameter can be increased without reducing the dimension between cage pockets, that is, the width of columns, as compared with the case of eight tracks, which is advantageous in terms of strength and torque load capacity. In addition, the conventional fixed type constant velocity universal joint has 3, 6, 8 tracks, and the number of tracks of the inboard-side joint is usually 3, 6, 8; Need. However, since the number of tracks is seven, the number of tracks is relatively prime to the number of tracks of the joint on the inboard side, so that there is no need for phase matching, which is advantageous in NVH characteristics.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a fixed type constant velocity universal joint according to an embodiment.
FIG. 2 is a cross-sectional view of the joint of FIG.
FIG. 3 is a diagram of a track groove.
FIG. 4 is a cross-sectional view of a fixed type constant velocity universal joint according to another embodiment.
FIG. 5 is a longitudinal sectional view of a fixed type constant velocity universal joint showing a conventional technique.
6 is a cross-sectional view of the joint of FIG.
FIG. 7 is a longitudinal sectional view similar to FIG. 5, showing a state where the joint has a bent angle.
FIG. 8 is a longitudinal sectional view of a fixed type constant velocity universal joint showing another conventional technique.
FIG. 9 is a cross-sectional view of the joint of FIG. 8;
FIG. 10 is a sectional view showing a relationship between a track groove and a ball.
[Explanation of symbols]
Reference Signs List 10 outer ring 12 inner peripheral surface 14 track groove 14a arc portion 14b straight portion 20 inner ring 22 outer peripheral surface 24 track groove 24a arc portion 24b straight portion 30 cage 32 outer peripheral surface 34 inner peripheral surface 36 pocket 40 ball O joint center (bending point)
θ Bending angle α Contact angle

Claims (2)

An outer ring having a plurality of track grooves for guiding the ball, an inner ring having a plurality of track grooves for guiding the ball, and a ball interposed between the outer ring track groove and the inner groove track groove to transmit torque. In a constant velocity universal joint comprising a cage interposed between an outer ring and an inner ring and arranging a plurality of balls on a bisecting plane of a bending angle of the joint,
The groove bottom of the outer ring track groove is located on the inner side of the outer ring and along the meridian of the sphere centering on the bending point of the joint, and on the opening side of the outer ring and straight toward the opening end of the outer ring It is composed of a straight part that has expanded in diameter,
The groove bottom of the track groove of the inner ring is located on the opening side of the outer ring, an arc portion along the meridian of the sphere centering on the bending point of the joint, and a straight portion linearly expanding toward the back side of the outer ring A fixed type constant velocity universal joint, comprising: 2. The constant velocity universal joint according to claim 1, wherein the outer ring has seven track grooves and the inner ring has seven track grooves.

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