JP2004332815A - Fixed type constant speed universal joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixed type constant speed joint which is higher in strength, longer in lifetime and higher in bending angle than a known fixed type constant speed joint at lower cost. <P>SOLUTION: In the constant speed universal joint comprising an outer ring 10 having a plurality of track grooves 14 to guide balls 40, an inner ring 20 having a plurality of track grooves 24 to guide the balls 40, the balls 40 which are interposed between the track grooves 14 of the outer ring 10 and the track grooves 24 of the inner ring 20 to transmit the torque, and a cage 30 with the plurality of balls 40 disposed on the bisecting plane of the bending angle of the joint, the center line of the ball track of the track grooves 14 of the outer ring 10 and the center line of the ball track grooves 24 of the inner ring 20 form an intersection of the ball with the bending point of the joint as a center thereof with a plane away from the center line not including the center line of the joint by at least the radius of the balls 40. <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]
As a fixed type constant velocity universal joint, a ball joint of a Zeppa type and a UF (undercut free) type has conventionally been known (Japanese Patent Publication No. 6-25567). The feature is that the track groove of the outer ring and the track groove of the inner ring are respectively formed along meridians of two spheres centered at points equidistant in the axial direction. As shown in FIGS. 17 and 18, 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 1 a of the outer ring 1 and an inner ring. The balls 4 are interposed one by one between the two track grooves 2a. As can be clearly understood from FIG. 17, the center of curvature of the track groove 1a of the outer ring 1 and the center of curvature of the track groove 2a of the inner ring 2 are offset in opposite directions in the axial direction with respect to the bending center of the joint. 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]
As an improvement of the above-described constant velocity universal joint, one disclosed in Japanese Patent No. 2916579 is known. The feature is a structure in which one ball which was conventionally on the meridian is replaced with two balls. That is, the track groove is formed by a pair of two track grooves that are parallel to each other, and each ball contacts only on a half surface of the groove so that only one-directional torque is applied. The cage has two balls in one window.
[0004]
Japanese Patent Publication No. 10033449 discloses a further improvement of the technique disclosed in Japanese Patent No. 2916579. The feature is that the center lines of the conventional Zeppa-type and UF-type track grooves are on a plane parallel to each other in pairs, and the cage is configured to hold two balls in one window. Each groove is a groove of a normal constant velocity universal joint which transmits a torque in both directions to the ball.
[0005]
[Patent Document 1]
Japanese Patent Publication No. 6-25567 (FIGS. 1 and 4)
[0006]
[Patent Document 2]
Japanese Patent No. 2916579 (FIGS. 1 and 2)
[0007]
[Patent Document 3]
German Offenlegungsschrift 100 33 491 (FIG. 2a)
[0008]
[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 joint strength or torque transmission.
{Circle around (1)} Generally, as shown in FIG. 19, the track grooves 1a and 2a hold the ball 4 in an angular manner, 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. That is, in consideration of the riding strength when receiving the torque, it is necessary to take measures against the strength corresponding to the weakest part, so that the parts other than the weakest part are wasteful in design.
{Circle around (2)} Since the center of curvature of the track groove is offset in the axial direction, the ball 4 moves radially in the pocket of the cage 3 when the joint rotates at a bending angle. As the bending angle increases, the ball hits the edge of the cage 3 (see FIG. 20), which is disadvantageous in securing the edge strength of the cage 3.
{Circle around (3)} Since the centers of curvature of the track grooves 1a, 2a are offset, one of the track grooves 1a, 2a has a narrow wedge shape in the axial direction and the other has a wide wedge shape. As a result, when a torque is applied to the joint, a component force is generated on the ball 4 in the joint axial direction, and the ball 4 is pressed against the cage 3. This has a disadvantageous effect on the strength of the window frame of the cage 3.
[0009]
The constant velocity universal joint disclosed in Japanese Patent No. 2916579 receives torque only in half of the track grooves, and is inferior in torque load capability.
[0010]
The constant velocity universal joint disclosed in German Patent Publication No. 100334491 has a problem in strength of the above-mentioned Zeppa-type or UF-type constant velocity universal joint, and has a large variation in the width of the inner spherical surface between adjacent tracks of the mouse of the outer ring. There is a problem. The same can be said for the outer spherical surface of the inner ring. The non-uniformity of the track groove depth and the large variation in the width of the spherical portion make forging more difficult.
[0011]
As shown in FIG. 20, in the conventional constant velocity universal joint, if the ball 4 is to be bent at a large angle, the ball 4 also falls out of the pocket of the cage 3 when the ball 4 comes off the track groove 1a of the outer ring 1. The deviation of the ball 4 from one track groove 1a is the limit of the bending angle.
[0012]
An object of the present invention is to realize a fixed type constant velocity universal joint which has higher strength, longer life, a higher bending angle, and lower cost than conventional fixed type constant velocity universal joints.
[0013]
[Means for Solving the Problems]
[0014]
The invention according to claim 1 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, a track groove 14 and the inner ring 20 of the outer ring 10. Fixed constant velocity universal joint comprising a ball 40 interposed between the track groove 24 and transmitting torque, and a cage 30 for arranging a plurality of balls 40 on a bisecting plane of a bending angle of the joint. In the above, the center line of the joint between the ball track center line of the track groove 14 of the outer ring 10 and the center line of the ball track of the track groove 24 of the inner ring 20 does not include the center line of the joint at the bending point of the joint. It is characterized by forming an intersecting line with a plane separated from the plane including the line by the radius of the ball 40 or more.
[0015]
According to a second aspect of the present invention, in the fixed type constant velocity universal joint according to the first aspect, the cage 30 holds two balls 40 forming a pair with one pocket 36.
[0016]
According to a third aspect of the present invention, in the fixed type constant velocity universal joint according to the first or second aspect, each pair of the track grooves 14 and 24 is parallel to the joint center line.
[0017]
According to a fourth aspect of the present invention, in the fixed type constant velocity universal joint according to the first or second aspect, each pair of the track grooves 14, 24 is inclined with respect to the joint center line. .
The invention of claim 5 is characterized in that, in the fixed type constant velocity universal joint according to any one of claims 1 to 4, the inner ring 20 and the shaft 5 are integrated.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0019]
First, the embodiment shown in FIGS. 1 and 2 will be described. FIG. 1 shows a longitudinal section (II section in FIG. 2) of the fixed type constant velocity universal joint, and FIG. 2 shows a transverse section. This constant velocity universal joint includes an outer ring 10, an inner ring 20, a cage 30, and a ball 40 as main components, and the outer ring 10 is connected to one rotating shaft (not shown), and the inner ring 20 is connected to the other. By connecting to the rotating shaft 5, the two shafts can be bent.
[0020]
FIG. 3 shows a vertical cross section of the outer race 10, and FIG. 4 shows a horizontal cross section (IV-IV cross section of FIG. 3) of the outer race 10. As shown in FIG. 3, the outer ring 10 has a cup-like shape opened at one end in the axial direction, and has a partially spherical inner peripheral surface 12. A track groove 14 extending in the axial direction is formed on the inner peripheral surface 12. The positions of the center of curvature of the inner peripheral surface 12 of the outer race 10 and the center of curvature of the track groove 14 coincide with each other in the axial direction, and also coincide with the bending center O of the joint. Therefore, the depth of the track groove 14 is constant without changing depending on the axial position. The curvature radius of the groove bottom of the track groove 14 is indicated by a reference symbol Ro in FIG. As can be seen from FIG. 4, the track grooves 14 are arranged in four pairs in the circumferential direction, and the track grooves 14 of each pair run parallel to each other across the center line of the joint. The distance L from the center line of the joint to the center line of the ball trajectory of each track groove 14 is equal to or greater than the radius of the ball 40. In other words, the ball track center line of the track groove 14 of the outer race 10 includes a sphere centered at the bending point of the joint (in FIG. 4, a sphere having a diameter of PCD) and a center line of the joint. Of the ball 40 from the plane including the center line of the ball 40 or more.
[0021]
FIG. 5 is a front view of the inner race 20, and FIG. 6 is a side view of the inner race 20. The inner race 20 has a partially spherical outer peripheral surface 22, and a track groove 24 extending in the axial direction is formed on the outer peripheral surface 22. The track grooves 24 of the inner ring 20 correspond to the track grooves 14 of the outer ring 10. That is, as can be seen from FIG. 6, the track grooves 24 are arranged in four pairs in the circumferential direction, and the track grooves 24 of each pair run parallel to each other across the center line of the joint. The distance (L) from the center line of the joint to the center line of the ball trajectory of each track groove 24 is greater than the radius of the ball 40. In other words, the ball trajectory center line of the track groove 24 of the inner race 20 includes a sphere centered on the bending point of the joint (a sphere having a diameter of PCD in FIG. 4) and a center line of the joint without including the center line of the joint. A line of intersection with a plane separated from the plane including the line by the radius of the ball 40 or more is formed. Similarly to the case of the outer ring 10, the center of curvature of the outer peripheral surface 22 of the inner ring 20 and the position of the center of curvature of the track groove 24 coincide with each other in the axial direction, and furthermore, the bending center O of the joint coincides with these. . Therefore, as can be seen from FIG. 1, the depth of the track groove 24 is constant without changing depending on the axial position. The radius of curvature of the groove bottom of the track groove 24 is indicated by a symbol Ri in FIG.
[0022]
As shown in FIG. 1, the track grooves 24 of the inner race 20 are formed only in an amount necessary to take a bending angle, so that the other portions can be increased in wall thickness to increase strength. it can. This will be described in more detail below. Conventional joints of this type require the inner ring to be bent at least 70 ° with respect to the outer ring in order to incorporate the ball at the end, and the bending angle required for the function (for example, 50 °) requires about 20 ° for assembly. Needed an extension of the truck. However, in this embodiment, since the balls are assembled first, only the tracks necessary for the operation need be formed. Therefore, the remaining track portion of about 20 ° is advantageous in terms of strength because meat can be left.
[0023]
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.
[0024]
7 is a longitudinal sectional view of the cage 30, FIG. 8 (a) is a transverse sectional view of the cage 30, and FIG. 8 (b) is a bb sectional view of FIG. 8 (a). The cage 30 has a spherical outer peripheral surface 32, a spherical inner peripheral surface 34, and four pockets 36 equally arranged in the circumferential direction. Since each pocket 36 accommodates two balls 40 (see FIG. 2), the cage 30 as a whole holds eight balls 40 in total. By allowing two balls 40 to be accommodated in one pocket 36, the number of pillars between the pockets 36 can be reduced as compared with the case where one ball is accommodated in one pocket, and the pillars can be made thicker accordingly. it can. Further, since the centers of curvature of the track grooves 14 and 24 coincide with each other, the ball 40 does not move in the radial direction even if the joint rotates with the bending angle. Therefore, as shown in FIG. 8B, a structure that holds the ball 40 in the radial direction can be adopted. FIG. 8B shows an arc-shaped cross section of the inner wall surface of the pocket 36 in the circumferential direction that is slightly larger than the outer diameter of the ball 40 so that the movement of the ball 40 to the outside in the radial direction can be restricted. Is illustrated.
[0025]
The outer peripheral surface 32 and the inner peripheral surface 34 of the cage 30 are concentric, and the radius of curvature of the outer peripheral surface 32 and the radius of curvature of the inner peripheral surface 34 are indicated by Co and Ci in FIG. 7, respectively. The outer peripheral surface 32 of the cage 30 and the inner peripheral surface 12 of the outer race 10 have the same radius of curvature with the same center of curvature and a predetermined clearance. The inner peripheral surface 34 of the cage 30 and the outer peripheral surface 22 of the inner race 20 have the same center of curvature and have substantially the same radius of curvature with a predetermined clearance. Therefore, the inner peripheral surface 12 of the outer race 10 is restricted by the outer peripheral surface 32 of the cage 30, and the inner peripheral surface 34 of the cage 30 is restricted by the outer peripheral surface 22 of the inner race 20.
[0026]
As shown in FIGS. 1 and 7, the inner peripheral surface 34 of the cage 30 is divided into the cage 30 and a ring 38. Reference numeral 39 indicates a retaining ring of the ring 38. With such a configuration, assembly becomes easy. That is, after the cage 30 is assembled into the outer race 10 and all the eight balls 40 are put in predetermined positions, the inner race 20 and the shaft 5 can be assembled after being connected by the serrations 26. Finally, the ring 38 is inserted and fixed with the retaining ring 39. Although not shown, the inner ring 20 and the shaft 5 may have an integrated structure.
[0027]
Next, the embodiment shown in FIGS. 9 and 10 will be described. The fixed type constant velocity universal joint according to this embodiment is such that the pair of track grooves parallel to each other in the above embodiment is inclined with respect to the center line of the joint.
[0028]
FIG. 11 shows a longitudinal section of the outer ring 50, and FIG. 12 shows a transverse section (XII-XII section of FIG. 11). The outer race 50 has a partially spherical inner peripheral surface 52, and four pairs of track grooves 54 are formed on the inner peripheral surface 52, as in the above-described embodiment. However, while they are parallel to each other in the above-described embodiment, here they are inclined with respect to the center line of the joint. In other words, the pair of track grooves 54 are widened from the deep end (left in FIG. 11) of the outer race 50 toward the open end (right in FIG. 11).
[0029]
FIG. 13 shows the front of the inner race 60, and FIG. The inner ring 60 has a partially spherical outer peripheral surface 62, and four pairs of track grooves 64 are formed on the outer peripheral surface 62. As in the case of the outer race 50, each pair of track grooves 64 is inclined with respect to the joint center line here, while being parallel to each other in the above embodiment. In other words, the pair of track grooves 64 extend from one end (the left side in FIG. 13) corresponding to the opening side of the outer ring 50 to the other end (the right side in FIG. 13) corresponding to the inner side of the outer ring 50. Has become. The two track grooves 54 forming a pair have a C-shape that is open to the mouse (opening) side, but may have a shape that is closed to the mouse side or a shape that is inclined in the same direction. However, the track groove 64 of the inner ring 60 has a shape corresponding to each.
[0030]
FIG. 15 shows the front of the cage 70, and FIG. The cage 70 has a spherical outer peripheral surface 72, a spherical inner peripheral surface 74, and four pockets 76 equally arranged in the circumferential direction. Since each pocket 76 accommodates two balls 80 (see FIG. 10), the cage 70 holds a total of eight balls 80. Also in this case, the number of columns between the pockets is smaller than that in the case where one ball is stored in each pocket, so that the columns can be made thicker. The inner peripheral surface 52 of the outer race 50 is restrained by the outer peripheral surface 72 of the cage 70, and the inner peripheral surface 74 concentric with the outer peripheral surface 72 of the cage 70 is restrained by the outer peripheral surface 62 of the inner race 60.
[0031]
【The invention's effect】
As described above, the track grooves generally hold the ball in an angular manner, and the larger the contact angle, the higher the load capacity. However, as described with reference to FIGS. 17 and 18, when the track groove depth is not uniform, the magnitude of the contact angle is determined by the shallowest part of the track groove, resulting in waste of design. According to the present invention, since the track groove depth is constant in the axial direction for both the inner and outer rings, even if the bending angle is increased, the contact point does not run over, which is advantageous in terms of strength. In addition, the PCD can be reduced by minimizing the minimum amount according to the strength being ensured. Since the PCD can be reduced, the outer diameter of the outer ring can be reduced to reduce the cost.
[0032]
In the present invention, since two adjacent track grooves are parallel to each other and have a constant spherical surface width, it is easy for the material to flow when crushed during forging. Further, since the track depth is constant, it is easy to crush and is easier to manufacture than a conventional non-uniform track groove.
[0033]
In the case of the conventional fixed type constant velocity universal joint, when rotating at a bending angle, the ball needs to move in the radial direction in the pocket of the cage, which is disadvantageous in securing the edge strength of the cage. According to the present invention, the ball does not move in the radial direction, and therefore, it is easy to secure the edge strength of the cage. In addition, since the ball does not move in the radial direction, the ball can be held in the cage to restrict the outward movement in the radial direction. Therefore, even if the ball gets out of the outer ring track groove, there is no fear of the ball jumping out, so that a high bending angle can be guaranteed. Further, since no axial component is applied to the cage window frame portion, it is advantageous in terms of strength.
[0034]
Since the track groove depth is constant, the cage thickness can be increased accordingly. Moreover, since the number of pockets can be increased to four and the pillar can be made thicker, it is advantageous in terms of machining and cost as compared with a conventional cage having eight pockets.
[0035]
Since the maximum diameter in the track groove radial direction coincides with the joint center for both the inner and outer races, it is possible to assemble the cage in the outer race with the ball inserted first and the inner race inserted later. In this case, the cage is disassembled and the inner peripheral surface at one end from the center of the width is formed of a separable member. Along with the possibility of assembling the ball in advance, the inner race and the shaft can be integrated. Furthermore, since the inner ring and the shaft have an integral structure, no serration is required, so that the outer diameter of the outer ring can be reduced, the number of parts can be reduced, and the cost can be reduced.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a fixed type constant velocity universal joint according to a first embodiment.
FIG. 2 is a sectional view taken along line I-II of FIG.
FIG. 3 is a longitudinal sectional view of an outer race of the fixed type constant velocity universal joint shown in FIG.
FIG. 4 is a view taken in the direction of arrows IV-IV in FIG. 3;
FIG. 5 is a front view of an inner race of the fixed type constant velocity universal joint shown in FIG. 1;
FIG. 6 is a side view of the inner race shown in FIG. 5;
FIG. 7 is a longitudinal sectional view of a cage of the fixed type constant velocity universal joint shown in FIG.
8 (a) is a cross-sectional view of the cage of FIG. 7,
FIG. 9B is a sectional view taken along line bb of FIG.
FIG. 9 is a longitudinal sectional view of a fixed type constant velocity universal joint according to a second embodiment.
FIG. 10 is a sectional view taken along line XX of FIG. 9;
11 is a longitudinal sectional view of an outer race of the fixed type constant velocity universal joint shown in FIG.
FIG. 12 is a view taken in the direction of arrows XII-XII in FIG.
FIG. 13 is a front view of the inner race of the fixed type constant velocity universal joint shown in FIG. 9;
FIG. 14 is a side view of the inner race of FIG.
FIG. 15 is a front view of a cage of the fixed type constant velocity universal joint shown in FIG. 9;
FIG. 16 is a cross-sectional view of the cage of FIG.
FIG. 17 is a longitudinal sectional view of a fixed type constant velocity universal joint showing a conventional technique.
18 is a cross-sectional view of the fixed type constant velocity universal joint shown in FIG.
FIG. 19 is a sectional view showing an angular contact between a ball and a track groove.
FIG. 20 is a vertical sectional view similar to FIG. 17 showing a state where a bending angle is set;
[Explanation of symbols]
10, 50 Outer ring 12, 52 Inner peripheral surface 14, 54 Track groove 20, 60 Inner ring 22, 62 Outer peripheral surface 24, 64 Track groove 30, 70 Cage 32, 72 Outer peripheral surface 34, 74 Inner peripheral surface 36, 76 Pocket 38 Ring 39 retaining ring 40,80 ball

Claims (5)

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. And a cage for arranging a plurality of balls on a bisecting plane of a bending angle of the joint, wherein a ball orbit center line of a track groove of an outer ring and a ball orbit center of a track groove of an inner ring are provided. The fixed line is characterized in that the line intersects a sphere centered at the bending point of the joint and a plane not including the center line of the joint but separated from the plane including the center line of the joint by a distance equal to or greater than the radius of the ball. Type constant velocity universal joint. The fixed type constant velocity universal joint according to claim 1, wherein the cage holds two balls forming a pair with one pocket. 3. The fixed type constant velocity universal joint according to claim 1, wherein each pair of track grooves is parallel to the joint center line. The fixed type constant velocity universal joint according to claim 1, wherein each pair of track grooves is inclined with respect to a joint center line. 5. The fixed type constant velocity universal joint according to claim 1, wherein the inner ring and the shaft are integrated.

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