阅读说明：本技术 固定式等速万向联轴器 (Fixed constant velocity universal joint ) 是由 藤尾辉明 船桥雅司 于 2020-03-16 设计创作，主要内容包括：一种固定式等速万向联轴器(1),外侧联轴器构件(2)的滚道槽(7)的轨道中心线(X)至少具备圆弧状部分,该圆弧状部分具有相对于联轴器中心(O)在轴向上没有偏置的曲率中心,包含轨道中心线(X)和联轴器中心(O)的平面(M)相对于联轴器的轴线(N-N)倾斜,并且该倾斜方向在周向上相邻的滚道槽(7)上形成为彼此相反的方向,内侧联轴器构件(3)的滚道槽(9)的轨道中心线(Y)形成为在工作角0°的状态下以包含联轴器中心(O)且与联轴器的轴线(N-N)正交的平面(P)为基准,与外侧联轴器构件(2)的成对的滚道槽(7)的轨道中心线(X)镜像对称,该固定式等速万向联轴器(1)的特征在于,具有在取得最大工作角(θmax)时向外侧联轴器构件(2)的滚道槽(7)的开口侧移动的至少一个转矩传递滚珠(4)与外侧联轴器构件(2)的滚道槽(7)的开口侧端部失去接触点的工作方式,在工作角0°的状态下,保持器(5)的端部从外侧联轴器构件(2)的开口侧端部沿轴向突出。(A fixed constant velocity universal joint (1) is provided with at least an arc-shaped portion having a curvature center that is not offset in the axial direction with respect to a joint center (O) and having a track center line (X) of a track groove (7) of an outer joint member (2), a plane (M) including the track center line (X) and the joint center (O) being inclined with respect to an axis (N-N) of the joint, and the inclination directions being formed in mutually opposite directions in circumferentially adjacent track grooves (7), a track center line (Y) of a track groove (9) of an inner joint member (3) being formed so as to be mirror-symmetrical with respect to the track center line (X) of a pair of track grooves (7) of the outer joint member (2) with respect to a plane (P) including the joint center (O) and orthogonal to the joint axis (N-N) in a state where an operating angle is 0 DEG, the fixed constant velocity universal joint (1) is characterized by having an operation mode in which at least one torque transmission ball (4) moving to the opening side of a track groove (7) of an outer joint member (2) and the opening side end of the track groove (7) of the outer joint member (2) lose a contact point when a maximum operation angle (theta max) is obtained, and in a state in which the operation angle is 0 DEG, the end of a retainer (5) axially protrudes from the opening side end of the outer joint member (2).)

1. A fixed constant velocity universal joint, comprising: an outer joint member having a spherical inner peripheral surface formed with a plurality of track grooves extending substantially in an axial direction and having an opening side and a rear side separated in the axial direction; an inner joint member having a spherical outer circumferential surface and a plurality of track grooves formed in the outer joint member so as to face the track grooves; torque transmission balls fitted between the track grooves facing each other; and a retainer that retains the torque transmission balls in pockets, and that has a spherical outer circumferential surface guided by the spherical inner circumferential surface of the outer joint member and a spherical inner circumferential surface guided by the spherical outer circumferential surface of the inner joint member, wherein a track center line (X) of a track groove of the outer joint member includes at least an arc-shaped portion having a curvature center that is not offset in an axial direction with respect to a joint center (O), a plane (M) including the track center line (X) and the joint center (O) is inclined with respect to an axis (N-N) of the joint, and the inclination directions are formed in mutually opposite directions on the circumferentially adjacent track grooves, and a track center line (Y) of a track groove of the inner joint member is formed in a state in which an operating angle is 0 DEG with respect to a plane (P) that includes the joint center (O) and is orthogonal to the axis (N-N) of the joint Mirror-symmetrical to the track centre line (X) of the track grooves of the outer coupling member pair,

the fixed type constant velocity universal joint is characterized in that,

the fixed type constant velocity universal joint has an operation mode that at least one torque transmission ball moving to the opening side of the track groove of the outer joint member when the maximum operation angle is obtained loses a contact point with the opening side end portion of the track groove of the outer joint member,

in a state of an operating angle of 0 °, an end of the retainer protrudes in an axial direction from an opening side end of the outer coupling member.

2. The fixed constant velocity universal joint according to claim 1,

the track centerline (X) of the track groove of the outer joint member comprises: a circular arc-shaped portion having a center of curvature that is not offset in an axial direction with respect to the coupling center (O); and a portion having a shape different from the circular arc portion, the circular arc portion and the portion having the different shape being smoothly connected at a connection point (J), the connection point (J) being located closer to the opening side of the outer joint member than the joint center (O).

3. The fixed constant velocity universal joint according to claim 1 or 2,

the different shaped portions are linear.

4. The fixed constant velocity universal joint according to any one of claims 1 to 3,

the socket-side end of the retainer is disposed on the rear side of the outer joint member.

5. The fixed constant velocity universal joint according to any one of claims 1 to 4,

in the retainer, an axial dimension (W) of an opening side with respect to a center of the pocket_F) Set to be larger than the axial dimension (W) of the inner side_E) Long.

6. The fixed constant velocity universal joint according to any one of claims 1 to 5,

axial dimension (W) of the open side of the retainer_F) A ratio (W) to an axial dimension (L1) from the coupling center (O) to an end surface of the outer coupling member on the opening side_Fand/L1) is 1.18 to 1.32.

7. The fixed constant velocity universal joint according to any one of claims 1 to 6,

the number of the torque transmission balls is set to be eight or more.

Technical Field

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

Background

A constant velocity universal joint constituting a power transmission system of an automobile or various industrial machines can connect two shafts on a driving side and a driven side so as to transmit torque, and can transmit rotational torque at a constant velocity even when the two shafts have operating angles. The constant velocity universal joint is roughly classified into a fixed type constant velocity universal joint that allows only angular displacement and a plunging type constant velocity universal joint that allows both angular displacement and axial displacement, and for example, in a drive shaft that transmits power from an engine of an automobile to drive wheels, the plunging type constant velocity universal joint is used on the differential side (inboard side) and the fixed type constant velocity universal joint is used on the drive wheel side (outboard side).

As functions to be achieved by a fixed type constant velocity universal joint for a drive shaft of an automobile, a high operating angle suitable for a steered wheel of a wheel and strength at the high operating angle accompanying the high operating angle are important. Conventionally, the maximum operating angle is usually 47 ° for a rzeppa type constant velocity universal joint (BJ type) and 50 ° for an undercut-free type constant velocity universal joint (UJ type), but there is an increasing demand for more than 50 ° from the viewpoint of improving the turning performance and the turning small bending performance of an automobile. In response to these demands, fixed type constant velocity universal joints of various structures have been proposed.

In the fixed type constant velocity universal joint, when the fixed type constant velocity universal joint is used at a high operating angle exceeding 50 ° of the conventional operating angle, it is necessary to shorten the length of the outer joint member so that the intermediate shaft does not interfere with the outer joint member, but as a result, the track grooves of the outer joint member become short, and the balls at a phase angle of about 0 ° are disengaged from the track grooves and lose contact points. As a method of extending the track grooves of the outer joint member, a method of increasing the Pitch Circle Diameter (PCD) of the balls is given, but the outer diameter of the outer joint member is increased, and the weight is increased.

Patent document 1 proposes a fixed type constant velocity universal joint having a structure in which the track grooves of the outer joint member and the inner joint member are formed in a combination of an arc shape and a tapered shape, thereby suppressing an increase in the outer diameter and enabling a high working angle.

In patent document 2, in a conventional fixed type constant velocity universal joint, the ratio of the axis parallel distance between the center of the ball and the joint center at a phase angle (phase angle 0 °) at which the torque transmission ball (hereinafter, simply referred to as ball) moves to the opening side of the outer joint member at the maximum operating angle to the axis parallel distance between the center of the ball and the opening conical surface of the outer joint member is less than 2.9, whereby the function can be maintained even at the maximum operating angle. When the operating angle is obtained and the balls project from the track grooves of the outer joint member to the point of loss of contact, the ratio can be made smaller than 2.2 to maintain the functionality. Further, as a means for increasing the maximum operating angle, the balls can be prevented from falling off from the cage and the outer joint member by setting the ratio of the axial distance between the ball center and the joint center in the phase (0 ° phase) in which the balls come out from the opening-side end portion of the outermost joint member at the maximum operating angle to the axial distance between the ball center and the opening conical surface of the outer joint member.

Patent document 3 proposes a highly efficient fixed type constant velocity universal joint which is not a fixed type constant velocity universal joint in which the maximum operating angle is set to an angle exceeding the conventional operating angle (50 °), but which includes: the track center lines of the track grooves of the outer joint member and the inner joint member include arc-shaped portions having centers of curvature that are not offset in the axial direction with respect to the joint center O, and the arc-shaped track center lines are inclined in opposite directions in the circumferential direction.

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 4041641

Patent document 2: japanese patent No. 4885236

Patent document 3: japanese patent laid-open publication No. 2013-104432

Disclosure of Invention

Problems to be solved by the invention

In the structure of patent document 1, although the increase in the outer diameter of the outer joint member is suppressed, the outer diameter of the outer joint member is increased in order to ensure the contact point between the balls and the track groove at a high operating angle because the track groove of the outer joint member is tapered toward the outer diameter side.

In the structure of patent document 2, when the balls protrude from the track grooves of the outer joint member at a high operating angle to lose the contact points, the balls remain in contact with the pockets of the cage (are held in the pockets of the cage), and thus the function is not impaired. However, it is clear that when the balls project from the track grooves of the outer joint member to the point of loss of contact, the balance of the forces acting on the cage is impaired compared to the case of having the contact point, and therefore, the balls are retained in the pockets of the cage, but the strength of the cage is not sufficient.

The fixed type constant velocity universal joint of patent document 3 has less torque loss and heat generation and is highly efficient, but has an unknown problem when used at a high operating angle exceeding the conventional operating angle (50 °). This problem was examined and verified as described below.

In view of the above-described problems, an object of the present invention is to provide a fixed type constant velocity universal joint capable of improving the strength of a cage while ensuring constant velocity, transmission efficiency, and durability in a fixed type constant velocity universal joint of an operation type in which a maximum operating angle is set to an angle exceeding a conventional operating angle (50 °) and balls lose contact points in a phase (phase angle 0 °) region coming out from an outer joint member when a high operating angle is obtained.

Means for solving the problems

The present inventors have made various studies and verifications on the above-described problems, and have obtained the following findings and ideas, thereby achieving the present invention.

(1) Disruption of the balance of forces within the coupling in the event of loss of ball contact

In the fixed type constant velocity universal joint, when the fixed type constant velocity universal joint is used at a high operating angle exceeding the conventional operating angle (50 °), the track grooves of the outer joint member become short as described above, and the balls at the phase angle of 0 ° or so are separated from the track grooves and lose contact points. In a phase range in which the balls lose their contact points with the track grooves, the contact force between the balls and the track grooves of the outer joint member and the track grooves of the inner joint member and the force applied from the balls to the cage are lost, and the load is received by the other balls, so that the balance of the internal forces is lost. In particular, it has been found that in a constant velocity universal joint of a ball cage type (BJ type) or an undercut-free type (UJ type) in which the center of curvature of the track groove is offset in the axial direction (hereinafter, also referred to as an axial track offset type), the balance of forces in the constant velocity universal joint is largely lost.

(2) Investigation of disruption of balance of forces within a coupling

In an axial track offset type fixed constant velocity universal joint, the center of curvature of the track grooves of the outer joint member is offset to the opening side of the outer joint member with respect to the joint center O, while the center of curvature of the track grooves of the inner joint member is offset in the direction opposite to the center of curvature of the track grooves of the outer joint member, and balls are disposed in a wedge-shaped space formed between the track grooves of the outer joint member and the track grooves of the inner joint member and opened to the opening side, and are positioned by a retainer.

When a torque is applied at a small angle of a normal angle, the balls press the cage in the same direction by the component force of the contact force between the track grooves of the outer joint member and the track grooves of the inner joint member, and therefore the spherical outer circumferential surface and the spherical inner circumferential surface of the cage are in strong contact with the spherical inner circumferential surface of the outer joint member and the spherical outer circumferential surface of the inner joint member, respectively. When a torque is applied at a medium angle to a high angle, the contact force between each ball and the track groove of the outer joint member and the contact force between each ball and the track groove of the inner joint member are strong and weak, and the force with which each ball presses the cage is also strong and weak, so that the mutual balance of the moments acting on the cages is slightly shifted from the plane of bisection. Further, at a high operating angle at which the balls lose contact points with the track grooves of the outer joint member, the number of balls sharing the load decreases, so that the balance of the moment of engagement with the cage greatly changes, and the cage is greatly displaced from the bisecting plane. It is considered that, along with this, the constant velocity and the transmission efficiency are reduced, and the strength of the retainer may be greatly reduced.

(3) Eyepoint and verification

From the above-described results of investigation, attention has been given to a cross-track groove type fixed type constant velocity universal joint having an excellent balance of forces acting from balls on a cage. In a fixed type constant velocity universal joint of a cross track groove type, track grooves of an outer joint member are formed in an arc shape having a curvature center that is not offset in an axial direction, are inclined in a circumferential direction with respect to an axis of the joint, and are formed in opposite directions with respect to each other in the inclination directions between adjacent track grooves, a track center line of the track grooves of an inner joint member is mirror-symmetrical to a track center line of the track grooves of the outer joint member, and balls are arranged at intersections between the track grooves of the outer joint member and the track grooves of the inner joint member.

In the fixed type constant velocity universal joint of the cross track groove type, when a torque is applied to a region from a small angle, a normal angle, a medium angle, and a high angle at which the balls and the track grooves come into contact with each other, a force is basically generated in the adjacent track grooves so that the balls press the cage in opposite directions to each other, and therefore the torque and the force of the cage generated by the action of the balls are balanced with each other. In the region of the intermediate angle to the high angle, the contact force between each ball and the track groove of the outer joint member and the contact force between each ball and the track groove of the inner joint member are strong and weak, but the moment and the force of the cage due to the action of the balls are balanced with each other as compared with the conventional axial raceway offset type, and therefore the cage is stabilized in the vicinity of the bisector plane. Further, it was found that even at a high operating angle at which the balls lose contact with the track grooves of the outer joint member, the moment and force of the cage due to the action of the balls act in directions balanced with each other, as compared with the conventional axial raceway offset type, and therefore the cage does not greatly deviate from the bisector plane.

According to the above verification results, the following conclusions are reached: in the fixed type constant velocity universal joint of the cross track groove type, the cage is not greatly displaced from the bisecting plane in a state where the balls lose contact points with the track grooves of the outer joint member, and the deterioration of the constant velocity and the transmission efficiency and the change of the internal force are limited to the minimum.

(4) New idea

The present invention was achieved based on the idea that a fixed type constant velocity universal joint of a cross-track groove type is used as a fixed type constant velocity universal joint of an operation type in which a maximum operating angle is set to an angle exceeding a conventional operating angle (50 °) and balls lose contact points at a phase angle (in the vicinity of a phase angle of 0 °) coming out from an outer joint member when a high operating angle is obtained.

As a means for achieving the above object, the present invention is a fixed type constant velocity universal joint including: an outer joint member having a spherical inner peripheral surface formed with a plurality of track grooves extending substantially in an axial direction and having an opening side and a rear side separated in the axial direction; an inner joint member having a spherical outer circumferential surface and a plurality of track grooves formed in the outer joint member so as to face the track grooves; torque transmission balls fitted between the track grooves facing each other; and a retainer that retains the torque transmission balls in pockets, and that has a spherical outer circumferential surface guided by the spherical inner circumferential surface of the outer joint member and a spherical inner circumferential surface guided by the spherical outer circumferential surface of the inner joint member, wherein a track center line (X) of a track groove of the outer joint member includes at least an arc-shaped portion having a curvature center that is not offset in an axial direction with respect to a joint center (O), a plane (M) including the track center line (X) and the joint center (O) is inclined with respect to an axis (N-N) of the joint, and the inclination directions are formed in mutually opposite directions on the circumferentially adjacent track grooves, and a track center line (Y) of a track groove of the inner joint member is formed in a state in which an operating angle is 0 DEG with respect to a plane (P) that includes the joint center (O) and is orthogonal to the axis (N-N) of the joint And a track center line (X) mirror-symmetrical to the track center line of the track grooves of the outer joint member, wherein the fixed type constant velocity universal joint has an operation mode in which at least one of the torque transmission balls moving toward the opening side of the track grooves of the outer joint member at a maximum operating angle is out of contact with the opening side end portions of the track grooves of the outer joint member, and an end portion of the cage axially protrudes from the opening side end portion of the outer joint member at an operating angle of 0 °.

With the above configuration, the following fixed type constant velocity universal joint can be realized: in a fixed type constant velocity universal joint of an operation type in which a maximum operating angle is set to an angle exceeding a conventional operating angle (50 DEG) and balls lose contact points at a phase angle (in the vicinity of a phase angle of 0 DEG) coming out from an outer joint member when a high operating angle is obtained, the strength of a cage can be improved while ensuring constant velocity, transmission efficiency and durability.

Specifically, it is preferable that the track center line X of the track groove of the outer joint member includes: a circular arc-shaped portion having a center of curvature that is not offset in the axial direction with respect to the coupling center O; and a portion having a shape different from the circular arc portion, the circular arc portion and the portion having a different shape being smoothly connected at a connection point J, the connection point J being located on the opening side of the outer joint member with respect to the joint center O. This makes it possible to adjust the length of the track groove effective for ensuring the contact point and the magnitude of the wedge angle at a high working angle while ensuring the constant speed and the transmission efficiency.

The effective raceway length can be increased by the different shapes of the linear portions.

Since the socket-side end portion of the retainer is disposed on the rear side of the outer joint member, the rigidity of the retainer can be improved.

Preferably, in the above-described retainer, an axial dimension (W) of the opening side with respect to a center of the pocket_F) Set to be larger than the axial dimension (W) of the inner side_E) Long. This can improve the strength of the retainer.

Preferably, the axial dimension (W) of the retainer on the opening side is set to be smaller than the axial dimension (W)_F) And a ratio (W) of an axial dimension (L1) from the coupling center (O) to the end surface of the outer coupling member on the opening side_Fand/L1) is 1.18 to 1.32. This makes it possible to insert the retainer into the outer joint member and to improve the strength of the retainer.

By setting the number of the torque transmission balls to eight or more, a practical and compact fixed constant velocity universal joint can be realized.

Effects of the invention

According to the present invention, the following fixed type constant velocity universal joint can be realized: in a fixed type constant velocity universal joint of an operation type in which a maximum operating angle is set to an angle exceeding a conventional operating angle (50 DEG) and balls lose contact points at a phase angle (in the vicinity of a phase angle of 0 DEG) coming out from an outer joint member when a high operating angle is obtained, the strength of a cage can be improved while ensuring constant velocity, transmission efficiency and durability.

Drawings

Fig. 1a is a longitudinal sectional view of a fixed type constant velocity universal joint according to an embodiment of the present invention.

Fig. 1b is a right side view of fig. 1 a.

Fig. 2a is a longitudinal section of the outer coupling member of fig. 1 a.

Fig. 2b is a right side view of fig. 2 a.

Fig. 3a is a front view of the inner coupling member of fig. 1 a.

Fig. 3b is a right side view of fig. 3 a.

Fig. 4 is an enlarged cross-sectional view of one of the torque transmitting balls and the track grooves on the line P-P of fig. 1 a.

Fig. 5 is a view obtained by comparing the vertical cross sections of the fixed type constant velocity universal joint of fig. 1a and a conventional fixed type constant velocity universal joint of a cross track groove type having the largest operating angle.

Fig. 6a is a longitudinal cross-sectional view of the fixed type constant velocity universal joint of fig. 1a and 1b at the maximum operating angle.

Fig. 6b is a right side view of fig. 6 a.

Fig. 7 is a vertical sectional view of an enlarged portion E of fig. 6 a.

Fig. 8 is a diagram showing the range in which the torque transmitting balls lose contact points with the track grooves of the outer joint member at the maximum operating angle in fig. 1 b.

Fig. 9 is a developed view of the inner peripheral surface of the outer joint member showing a state in which the range in which the track grooves of the outer joint member of fig. 8 lose contact points with the torque transmission balls differs depending on the direction of inclination of the track grooves.

Fig. 10 is a longitudinal sectional view illustrating dimensional characteristics of the fixed type constant velocity universal joint shown in fig. 1 a.

Fig. 11 is a side view showing a state where the retainer is fitted into the outer joint member.

Detailed Description

A fixed type constant velocity universal joint according to an embodiment of the present invention will be described with reference to fig. 1 to 11. Fig. 1a is a longitudinal sectional view of a fixed type constant velocity universal joint according to an embodiment of the present invention, and fig. 1b is a right side view of fig. 1 a. Fig. 2a is a longitudinal sectional view of the outer coupling member of fig. 1a, and fig. 2b is a right side view of fig. 2 a. Fig. 3a is a longitudinal section of the inner coupling member of fig. 1a, and fig. 3b is a right side view of fig. 3 a. As shown in fig. 1a and 1b, the fixed type constant velocity universal joint 1 of the present embodiment is a cross-track groove type fixed type constant velocity universal joint, and has an outer joint member 2, an inner joint member 3, torque transmission balls (hereinafter, also simply referred to as balls) 4, and a cage 5 as main components. Eight track grooves 7 are formed in the spherical inner peripheral surface 6 of the outer joint member 2, and eight track grooves 9 are formed in the spherical outer peripheral surface 8 of the inner joint member 3 so as to face the track grooves 7 of the outer joint member 2. A cage 5 for holding the balls 4 is disposed between the spherical inner peripheral surface 6 of the outer joint member 2 and the spherical outer peripheral surface 8 of the inner joint member 3. The spherical outer peripheral surface 12 of the retainer 5 is slidably fitted to the spherical inner peripheral surface 6 of the outer joint member 2, and the spherical inner peripheral surface 13 of the retainer 5 is slidably fitted to the spherical outer peripheral surface 8 of the inner joint member 3.

The spherical inner peripheral surface 6 of the outer joint member 2 and the spherical outer peripheral surface 8 of the inner joint member 3 have centers of curvature formed at the joint center O, and the spherical outer peripheral surface 12 and the spherical inner peripheral surface 13 of the retainer 5 fitted to the spherical inner peripheral surface 6 of the outer joint member 2 and the spherical outer peripheral surface 8 of the inner joint member 3 are also located at the joint center O.

An inner spline (spline including serration) 11 is formed in the inner diameter hole 10 of the inner joint member 3, and an outer spline 15 formed at an end portion of an intermediate shaft 14 (see fig. 6a) is fitted into the inner spline 11 to be connected so as to be capable of transmitting torque. The inner coupling member 3 and the intermediate shaft 14 are positioned in the axial direction by a collar 16.

As shown in fig. 1a, 1b, 2a, 2b, 3a and 3b, the eight track grooves 7, 9 of the outer joint member 2 and the inner joint member 3 extend substantially in the axial direction. The track grooves 7, 9 are inclined in the circumferential direction with respect to the joint axis N-N, and the inclination directions are formed in mutually opposite directions on the circumferentially adjacent track grooves 7A, 7B and 9A, 9B. Eight balls 4 are disposed at each intersection of the paired track grooves 7A, 9A, 7B, and 9B of the outer joint member 2 and the inner joint member 3. In fig. 1a, the track grooves 7 and 9 are shown in a state in which the cross sections of the plane M shown in fig. 2a and the plane Q shown in fig. 3a are rotated until the inclination angle γ becomes 0 °. In the operating angle 0 state, the coupling axis N-N is also the axis of the outboard coupling member No-No and the axis of the inboard coupling member Ni-Ni.

The track center line (X) of the track groove of the outer joint member in the technical proposal comprises: a circular arc-shaped portion having a center of curvature that is not offset in the axial direction with respect to a coupling center (O); and a portion having a shape different from the arc-shaped portion, the arc-shaped portion and the portion having a different shape being smoothly connected at a connection point (J), the connection point (J) being located closer to the opening side of the outer joint member than the joint center (O) ". The track center line X of the track groove of the outer joint member includes: a circular arc-shaped portion having a center of curvature that is not offset in the axial direction with respect to the coupling center O; and a portion having a shape different from the arc-shaped portion, the length of the track groove effective for ensuring the contact point and the magnitude of the wedge angle at a high working angle can be adjusted while ensuring the constant speed, the transmission efficiency, and the durability.

As shown in fig. 1a, the track groove 7 of the outer joint member 2 has a track center line X, and the track groove 7 includes: a first track groove portion 7a having an arc-shaped track center line Xa with the joint center O as a curvature center; and a second track groove portion 7b having a linear track center line Xb, the track center line Xb of the second track groove portion 7b being smoothly connected as a tangent to the track center line Xa of the first track groove portion 7 a. The linear portion has a shape different from the circular arc portion. The track center line Xa of the first track groove portion 7a means at least "an arc-shaped portion having a curvature center that is not offset in the axial direction with respect to the joint center (O)" that the track center line X of the track groove of the outer joint member in the present specification and claims includes.

In order to accurately show the form and shape of the track groove extending substantially in the axial direction, the present specification will be described using terms such as the track center line. Here, the track center line refers to a track drawn by the center of the ball when the ball disposed in the track groove moves along the track groove.

As shown in fig. 1a, the track groove 9 of the inner joint member 3 has a track center line Y, and the track groove 9 includes: a first track groove portion 9a having an arc-shaped track center line Ya with the coupling center O as a curvature center; and a second track groove portion 9b having a linear track center line Yb, the track center line Yb of the second track groove portion 9b being smoothly connected as a tangent at the track center line Ya of the first track groove portion 9 a. By disposing the respective centers of curvature of the track center lines Xa, Ya of the first track groove portions 7a, 9a of the outer joint member 2 and the inner joint member 3 on the joint center O, that is, the joint axis N-N, the track groove depths can be made uniform and the processing can be made easy.

The state in which the track grooves 7 of the outer joint member 2 are inclined in the circumferential direction with respect to the joint axis N-N will be described in detail with reference to fig. 2a and 2 b. The track grooves 7 of the outer joint member 2 are denoted by reference numerals for the track grooves 7A and 7B depending on the inclination direction thereof. As shown in fig. 2a, a plane M containing the track centre line X of the track grooves 7A and the joint centre O is inclined at an angle γ with respect to the joint axis N-N. Although not shown, the track groove 7B circumferentially adjacent to the track groove 7A is inclined at an angle γ in a direction opposite to the inclination direction of the track groove 7A with respect to the joint axis N-N, on a plane M including the track center line X of the track groove 7B and the joint center O.

In the present embodiment, the entire track center line X of the track groove 7A, that is, both the track center line Xa of the first track groove portion 7A and the track center line Xb of the second track groove portion 7b are formed on the plane M.

Here, the reference numerals of the track grooves are supplemented. When the entire track groove of the outer joint member 2 is shown, the reference numeral 7 is given to the first track groove portion, the reference numeral 7a is given to the second track groove portion, and the reference numeral 7b is given to the second track groove portion. When the track grooves having different inclination directions are distinguished, the reference numerals 7A and 7B are given, the reference numerals 7Aa and 7Ba are given to the respective first track groove portions, and the reference numerals 7Ab and 7Bb are given to the respective second track groove portions. The track grooves of the inner joint member 3 described later are also denoted by the same reference numerals in accordance with the same rule.

Next, a state in which the track grooves 9 of the inner joint member 3 are inclined in the circumferential direction with respect to the joint axis N-N will be described in detail with reference to fig. 3a and 3 b. The track grooves 9 of the inner joint member 3 are denoted by reference numerals for the track grooves 9A and 9B depending on the inclination direction thereof. As shown in fig. 3a, a plane Q containing the track centre line Y of the track grooves 9A and the joint centre O is inclined at an angle γ with respect to the joint axis N-N. Although not shown, the track groove 9B adjacent to the track groove 9A in the circumferential direction is inclined at an angle γ in a direction opposite to the inclination direction of the track groove 9A with respect to the joint axis N-N, on a plane Q including the track center line Y of the track groove 9B and the joint center O. The inclination angle γ is preferably 4 ° to 12 ° in consideration of workability of the fixed type constant velocity universal joint 1 and the spherical surface width I on the side of the inner joint member 3 closest to the track groove 9.

In the present embodiment, as in the case of the outer joint member 2 described above, the entire track center line Y of the track groove 9A, that is, both the track center line Ya of the first track groove portion 9A and the track center line Yb of the second track groove portion 9b, are formed on the plane Q. The track center line Y of the track groove 9 of the inner joint member 3 is formed by: in the state of the working angle of 0 °, the track center line X of the track groove 7 of the outer joint member 2 is mirror-symmetrical with respect to a plane P including the joint center O and orthogonal to the joint axis N-N.

The details of the track grooves as seen in the longitudinal cross-section of the outer joint member 2 and the inner joint member 3 will be described with reference to fig. 1 a. As described above, in fig. 1a, the track grooves 7 and 9 are shown in a state in which the cross sections of the plane M shown in fig. 2a and the plane Q shown in fig. 3a are rotated to an inclination angle γ of 0 °, respectively. That is, the outer joint member 2 is a cross-sectional view as viewed on a plane M including the track center line X of the track groove 7A of the outer joint member 2 and the joint center O in fig. 2 a. Therefore, strictly speaking, a cross section inclined at an angle γ is shown, not a longitudinal cross section of a plane containing the axis N-N of the coupling. In fig. 1a, the track groove 7A of the outer joint member 2 is shown, but the track groove 7B is inclined in the opposite direction to the track groove 7A, and the other configuration is the same as the track groove 7A, and therefore, the description thereof is omitted. The spherical inner peripheral surface 6 of the outer joint member 2 is formed with a track groove 7A substantially in the axial direction.

The track groove 7A has a track center line X, and the track groove 7A includes: a first track groove portion 7Aa having an arc-shaped track center line Xa with the joint center O as a curvature center (no axial offset); and a second track groove portion 7Ab having a linear track center line Xb. At the opening-side end portion J of the track center line Xa of the first track groove portion 7Aa, the linear track center line Xb of the second track groove portion 7Ab is smoothly connected as a tangent. That is, the end portion J is a connection point between the first track groove portion 7Aa and the second track groove 7 Ab. Since the end portion J is positioned on the opening side with respect to the joint center O, the linear track center line Xb of the second track groove portion 7Ab connected as a tangent to the opening side end portion J of the track center line Xa of the first track groove portion 7Aa is formed so as to approach the joint axis N-N toward the opening side. This can increase the effective track length and suppress an excessive wedge angle.

As shown in fig. 1a, a straight line connecting the end portion J and the joint center O is denoted by S. The joint axis N ' -N ' projected on the plane M including the track center line X of the track groove 7A and the joint center O is inclined at γ with respect to the joint axis N-N, and an angle formed by a straight line S and a perpendicular line K at the joint center O of the axis N ' -N ' is defined as β '. The perpendicular line K is on a plane P that includes the joint center O and is orthogonal to the joint axis N-N at the operating angle of 0 °. Therefore, the angle β of the straight line S with respect to the plane P in the present invention is sin β' × cos γ.

Similarly, the details of the track grooves will be described with reference to fig. 1a, in a longitudinal section of the inner joint member 3. The illustration is a cross-sectional view seen at a plane Q containing the joint center O and the track centre line Y of the track grooves 9A of the inner joint member 3 of fig. 3 a. Therefore, strictly speaking, a cross section inclined at an angle γ is shown, not a longitudinal cross section of a plane containing the axis N-N of the coupling. In fig. 1a, the track groove 9A of the inner joint member 3 is shown, but the track groove 9B is inclined in the opposite direction to the track groove 9A, and the other structure is the same as the track groove 9A, and therefore, the description thereof is omitted. The spherical outer peripheral surface 8 of the inner joint member 3 has track grooves 9A formed substantially in the axial direction.

The track groove 9A has a track center line Y, and the track groove 9A includes: a first track groove portion 9Aa having an arc-shaped track center line Ya with the joint center O as a curvature center (no axial offset); and a second track groove portion 9Ab having a linear track center line Yb. At the end portion J' on the back side of the track center line Ya of the first track groove portion 9Aa, the track center line Yb of the second track groove portion 9Ab is smoothly connected as a tangent. That is, the end portion J' is a connection point of the first track groove portion 9Aa and the second track groove 9 Ab. Since the end portion J 'is located on the back side of the joint center O, the linear track center line Yb of the second track groove portion 9Ab connected as a tangent to the end portion J' on the back side of the track center line Ya of the first track groove portion 9Aa is formed so as to approach the joint axis N-N as it goes to the back side. This can increase the effective track length and suppress an excessive wedge angle.

As shown in fig. 1a, a straight line connecting the end portion J 'and the joint center O is denoted as S'. The joint axis N '-N' projected on the plane Q including the track center line Y of the track groove 9A and the joint center O is inclined at γ with respect to the joint axis N-N, and an angle formed by a perpendicular line K at the joint center O of the axis N '-N' and the straight line S 'is defined as β'. The perpendicular line K is on a plane P that includes the joint center O and is orthogonal to the joint axis N-N at the operating angle of 0 °. Therefore, an angle β of the straight line S 'with respect to a plane P including the joint center O in a state of the operating angle 0 ° is in a relationship of sin β' × cos γ.

Next, an angle β formed by the straight line S, S' with respect to a plane P including the joint center O and orthogonal to the joint axis N-N in a state where the operating angle is 0 ° will be described. When the operating angle θ is obtained, the balls 4 move by θ/2 with respect to a plane P including the joint centers O of the outer joint member 2 and the inner joint member 3. The angle β is determined by using 1/2 which is an operating angle with a high frequency, and the range of the track groove with which the ball 4 contacts is determined in the range of the operating angle with a high frequency. Here, a common angle with a high frequency of use is defined. The normal angle of the joint is an operating angle generated by a fixed type constant velocity universal joint of a front drive shaft when a steering direction is set to a straight traveling state in a motor vehicle in which one passenger is present on a horizontal and flat road surface. The usual angle is usually 2 ° to 15 °, and is selected and determined according to the design conditions of each vehicle type.

According to the angle β, in fig. 1a, the end portion J of the raceway center line Xa of the first track groove portion 7Aa is a center position of the ball when moving to the side closest to the opening in the axial direction at the normal angle. Similarly, in the inner joint member 3, the end portion J' of the raceway center line Ya of the first track groove portion 9Aa is a center position of the ball when moving to the innermost side in the axial direction at the normal angle. Since the balls 4 are positioned in the first track groove portions 7Aa and 9Aa of the outer joint member 2 and the inner joint member 3 and in the opposite inclination directions 7Ba and 9Ba within the normal angle range, a force in the opposite direction acts on the circumferentially adjacent pocket portions 5a of the cage 5 from the balls 4, and the cage 5 is stabilized at the joint center O (see fig. 1 a). Therefore, the contact force between the spherical outer peripheral surface 12 of the cage 5 and the spherical inner peripheral surface 6 of the outer joint member 2 and the contact force between the spherical inner peripheral surface 13 of the cage 5 and the spherical outer peripheral surface 8 of the inner joint member 3 are suppressed, torque loss and heat generation are suppressed, and durability is improved.

In the range of high operating angle, the balls 4 arranged in the circumferential direction are temporarily spaced apart and positioned in the first track groove portions 7Aa and 9Aa and the second track groove portions 7Ab and 9 Ab. Accordingly, contact forces are generated between the cage 5 and the spherical contact portions 12 and 6 of the outer joint member 2 and between the cage 5 and the spherical contact portions 13 and 8 of the inner joint member 3, but the moment and the force of the cage 5 generated by the action of the balls 4 are balanced with each other as compared with the conventional axial raceway offset type, and therefore the cage 5 is stabilized in the vicinity of the bisector plane. Further, since the use frequency of the high operating angle range is low, the fixed type constant velocity universal joint 1 of the present embodiment can suppress torque loss and heat generation in general. Therefore, a fixed type constant velocity universal joint with less torque loss and heat generation and high efficiency can be realized.

Fig. 4 is a cross-sectional view of one of the balls and the track grooves on the line P-P of fig. 1a, enlarged. However, the track grooves 7 and 9 are shown in a state in which the cross sections of the plane M shown in fig. 2a and the plane Q shown in fig. 3a are rotated to the inclination angle γ of 0 °, respectively. The cross-sectional shapes of the track grooves 7 of the outer joint member 2 and the track grooves 9 of the inner joint member 3 are elliptical and pointed arch shapes, and as shown in fig. 4, the balls 4 contact the track grooves 7 of the outer joint member 2 at two points C1 and C2 and contact the track grooves 9 of the inner joint member 3 at two points C3 and C4. An angle (contact angle α) formed by a straight line passing through the center Ob of the ball 4 and the contact points C1, C2, C3, and C4 and a straight line passing through the center Ob of the ball 4 and the joint center O (see fig. 1a) is preferably set to 30 ° or more. The cross-sectional shape of the track grooves 7, 9 may be an arc shape, and the contact between the track grooves 7, 9 and the balls 4 may be annular contact.

The entire structure of the fixed type constant velocity universal joint 1 according to the present embodiment is as described above. The fixed type constant velocity universal joint 1 according to the present embodiment is set to a maximum operating angle that greatly exceeds 50 °, but has a characteristic configuration as follows.

(1) In a fixed constant velocity universal joint of a cross raceway groove type, an operation mode in which balls lose contact points when a maximum operating angle is obtained is realized.

(2) Further, in a state of the operating angle of 0 °, an end portion of the cage protrudes in the axial direction from an opening side end portion of the outer coupling member.

With the above-described structure, in the fixed type constant velocity universal joint of the cross track groove type, the operation mode in which the balls lose their contact points when the maximum operating angle is obtained is set, even at high operating angles where the balls 4 lose their contact point with the track grooves 7 of the outer joint member 2, since the moment of the cage 5 and the force generated by the action of the balls 4 act in directions balanced with each other, therefore, the retainer 5 is not greatly displaced from the bisecting plane, the decrease of the constant velocity and the transmission efficiency and the change of the internal force can be limited to the minimum, a characteristic structure (2) is combined with a favorable characteristic structure (1) based on the fixed constant velocity universal joint of the cross raceway groove type, thus, a fixed type constant velocity universal joint can be realized which can ensure constant velocity, transmission efficiency, and durability and can improve the strength of the retainer.

First, a characteristic structure (1) of the fixed type constant velocity universal joint 1 according to the present embodiment will be described with reference to fig. 5. The upper half of the center line (joint axis line) of fig. 5 is a longitudinal sectional view of the fixed type constant velocity universal joint 1 according to the present embodiment, and the lower half thereof is a longitudinal sectional view of a conventional fixed type constant velocity universal joint of a cross track groove type using eight balls having a maximum working angle. The maximum operating angle of the conventional fixed type constant velocity universal joint 101 having the cross track groove type with the maximum operating angle shown in the lower half is 47 °. The fixed type constant velocity universal joint 101 mainly has an outer joint member 102, an inner joint member 103, balls 104, and a cage 105. The track grooves 107 and 109 of the outer joint member 102 and the inner joint member 103 of the fixed constant velocity universal joint 101 are the same as the track grooves 7 and 9 of the present embodiment, and therefore only the outline will be described.

The track grooves 107, 109 of the outer joint member 102 and the inner joint member 103 of the fixed constant velocity universal joint 101 are formed by first track groove portions 107a, 109a and second track groove portions 107b, 109b, respectively. The first track groove portions 107a, 109a have arcuate track center lines xa, ya, respectively, with the joint center O as a curvature center (no axial offset), and the second track groove portions 107b, 109b have linear track center lines xb, yb, respectively. The track center line xa of the first track groove portion 107a of the outer joint member 102 and the track center line xb of the second track groove portion 107b are connected smoothly with a tangent at a connection point a on the opening side with respect to the joint center O. The track center line ya of the first track groove portion 109a of the inner joint member 103 and the track center line yb of the second track groove portion 109b are smoothly connected at the connection point a' on the inner side with a tangent line.

Like the fixed type constant velocity universal joint 1 of the present embodiment, the track grooves 107, 109 of the outer joint member 102 and the inner joint member 103 are each inclined in the circumferential direction with respect to the joint axis N-N, and the track grooves 107, 109 adjacent in the circumferential direction are each inclined in the opposite direction. An angle β of a straight line L, L 'connecting the connection point A, A' and the joint center O with respect to a plane P containing the joint center O and orthogonal to the joint axis N-N₁The angle β is set larger than the angle β of the fixed type constant velocity universal joint 1 of the present embodiment.

The fixed type constant velocity universal joint 101 has an operation mode in which a contact state between the balls 104 and the track grooves 107 of the outer joint member 102 is always ensured up to the maximum operation angle (47 °). The inlet chamfer 120 provided at the open-side end of the outer joint member 102 is set so as not to interfere with the intermediate shaft at the maximum operating angle and to ensure the contact state of the balls 104 with the track grooves 107 of the outer joint member 102. Therefore, the axial dimension L2 of the end surface of the outer joint member 102 from the joint center O to the opening side is set to be relatively long.

In the case where a high operating angle in which the maximum operating angle exceeds 47 ° is required, the intermediate shaft interferes with the inlet chamfer 120, and therefore, in order to avoid this, the inlet chamfer 120 is moved in the axial direction toward the coupling center O side and the inclination angle is increased as appropriate, but accompanying this, the axial dimension of the end surface of the outer coupling member 102 from the coupling center O to the opening side needs to be shortened. In contrast, the fixed type constant velocity universal joint 1 according to the present embodiment is set to a value that greatly exceeds the conventional maximum operating angle. In the fixed type constant velocity universal joint 1 of the present embodiment shown in the upper half of fig. 5, the axial dimension L1 from the joint center O to the end surface on the opening side of the outer joint member 2 is shorter than the axial dimension L2 from the joint center O to the end surface on the opening side of the outer joint member 102 of the conventional fixed type constant velocity universal joint 101 having the largest working angle shown in the lower half.

The present embodiment is described with reference to fig. 6a and 6bThe state when the fixed type constant velocity universal joint 1 obtains the maximum operating angle will be described. Fig. 6a is a longitudinal sectional view of the fixed type constant velocity universal joint 1 at the maximum operating angle, and fig. 6b is a right side view of fig. 6 a. As described above, since the length of the track grooves 7 on the opening side of the outer joint member 2 is reduced, the fixed type constant velocity universal joint 1 according to the present embodiment operates in a state in which the balls 4 are disengaged from the end portions on the opening side of the track grooves 7 of the outer joint member 2 and lose contact points with the track grooves 7 when the maximum operating angle θ max is significantly larger than the conventional one, as shown in fig. 6 a. Further, the balls 4 are disengaged from the inner end of the track groove 9 of the inner joint member 3 and lose the contact point with the track groove 9. When the maximum operating angle θ max is obtained, as shown in fig. 6b, the center Ob of the ball 4 is at a phase angle of 0 ° (v °)Is maximally deviated from the opening side end portion of the track groove 7 of the outer joint member 2.

Fig. 6a shows a state in which the axis Ni-Ni of the inner joint member 3 (intermediate shaft 14) is bent to a maximum operating angle θ max (e.g., 55 °) on the paper plane of the figure with respect to the axis No-No of the outer joint member 2. The axis Nc-Nc of the holder 5 is inclined at a halving angle θ max/2. Here, the phase angle 0 ° is defined as an angular position in the circumferential direction of the center Ob of the ball 4 on the uppermost side (top) in the state where the operating angle shown in fig. 1b is 0 °. In the present specification and claims, the phase angle is from 0 ° (denoted as 0 ° in fig. 6 b)Hereinafter also referred to as) A rule that increases in the counterclockwise direction. In the present specification and claims, the maximum operating angle θ max is used in the sense of the maximum operating angle that the fixed type constant velocity universal joint 1 can allow in use.

In fig. 6a, the intermediate shaft 14 is shown in a state of abutting against the inlet chamfer 20 at the maximum operating angle, but actually, the inlet chamfer 20 is set to have a shape and a size slightly surplus between the maximum operating angle and the outer diameter surface of the intermediate shaft 14, and the inlet chamfer 20 functions as a stopper surface when the intermediate shaft 14 exceeds the maximum operating angle.

As shown in fig. 6a, in the fixed type constant velocity universal joint 1 of the present embodiment, when the maximum operating angle is obtained, the phase angle is a phase angle that moves toward the opening side of the track groove 7 of the outer joint member 2The adjacent balls 4 are separated from the end (inlet chamfer 20) of the outer joint member 2 on the opening side of the track groove 7 and lose contact with the track groove 7, and the balls 4 are separated from the end of the inner joint member 3 on the back side of the track groove 9 and lose contact with the track groove 9. The details of this state will be described with reference to fig. 7 in which the section E of fig. 6a is enlarged.

The inlet chamfers 20 formed at the end portions of the opening side of the outer joint member 2, the surface positions 4ao, 4ai of the balls 4 in the case of contact with the track grooves 7, 9, and the surface position 4b of the ball 4 in contact with the pocket 5a of the cage 5 are indicated by broken lines. Note that, a contact point locus obtained by axially coupling the contact point C2 (or C1, see fig. 4) of the ball 4 with the track groove 7 of the outer joint member 2 is represented by CLo, and a contact point locus obtained by axially coupling the contact point C3 (or C4, see fig. 4) of the ball 4 with the track groove 9 of the inner joint member 3 is represented by CLi, which are shown by broken lines. The contact point trajectories CLo, CLi are formed at positions separated from the groove bottoms of the track grooves 7, 9.

The contact point trajectory CLo ends at the opening side of the outer joint member 2 and at the edge of the inlet chamfer 20. The edge of the inlet chamfer 20 is an end of the outer joint member 2 on the opening side of the track groove 7. The surface position 4ao of the ball 4 is shifted in the right direction of fig. 7 with respect to the terminal end of the contact point trajectory CLo, and the ball 4 and the track groove 7 are in a non-contact state. The number of the balls 4 losing the contact point with the track groove 7 is about 1-2 out of eight. The balls 4 do not participate in torque transmission. The contact point trajectory CLi of the track groove 9 of the inner joint member 3 ends at the inner end 3 a. The surface position 4ai of the ball 4 is shifted in the left direction of fig. 7 with respect to the terminal end of the contact point locus CLi, and the ball 4 and the track groove 9 are in a non-contact state. The offset amount between the surface position 4ao of the ball 4 and the terminal end of the contact point trajectory CLo of the track groove 7 of the outer joint member 2 is set larger than the offset amount between the surface position 4ai of the ball 4 and the terminal end of the contact point trajectory CLi of the track groove 9 of the inner joint member 3.

The surface position 4b of the ball 4 is in contact with the pocket 5a at a radial position of the retainer 5 in front of the spherical outer peripheral surface 12. Further, the pockets 5a and the balls 4 are fitted with an extremely small interference, and the balls 4 are reliably held in the pockets 5a because of the non-contact state with the track grooves 9 of the inner joint member 3 and there is no inevitable interference between the track grooves 9 and the balls 4, thereby preventing the occurrence of abnormal noise and the like. Even if the ball 4 should be detached from the pocket 5a, the distance W between the edge of the inlet chamfer 20 of the track groove 7 and the edge of the pocket 5a of the cage 5 is set to be Db > W with respect to the diameter Db of the ball 4, and therefore, the ball 4 is prevented from falling off.

Next, a range in which the ball 4 is separated from the track groove 7, that is, a range of a phase angle at which the ball 4 and the track groove 7 are in a non-contact state (hereinafter, also simply referred to as a range) will be described with reference to fig. 8. Fig. 8 is a view showing the range in which the balls 4 are disengaged from the track grooves 7 of the outer joint member 2 at the maximum operating angle in fig. 1 b. In fig. 8, the range in which the balls 4 are disengaged from the track grooves 7 of the outer joint member 2 is indicated by arrows. The lead line of each arrow indicates the center Ob of the ball 4. In the fixed type constant velocity universal joint 1 of the present embodiment, the track grooves 7A, 7B of the outer joint member 2 have the inclination angle γ in the circumferential direction with respect to the joint axis N-N, and the inclination directions of the track grooves 7A, 7B adjacent in the circumferential direction are formed in the directions opposite to each other, so that the phase angle range M in which the balls 4 are disengaged from the track grooves 7A_ARange of phase angle M out of track groove 7B_BAs shown in fig. 8 with a slight difference.

With reference to FIGS. 6a, 6b andthe range in which the ball 4 is separated from the track groove 7 will be specifically described by taking the one ball 4 positioned in the track groove 7A in the ball 8 as an example. The axis No-No of the outer joint member 2 and the axis Ni-Ni of the inner joint member 3 (intermediate shaft 14) shown in FIG. 6a are set to be constant, and the fixed type constant velocity universal joint 1 is set from a phase angleWhen rotating in the counterclockwise direction, the phase angle is shown in FIG. 8Near phase angle of(for example,) The balls 4 are disengaged from the end of the outer joint member 2 on the opening side of the track groove 7A and start to lose the non-contact state with the contact point with the track groove 7A. Then, the phase angle is crossedAt a phase angle(for example,) The balls 4 return to the end of the outer joint member 2 on the opening side of the track groove 7A and start to contact the track groove 7A.

In the above description, although one ball 4 is taken as an example, when the fixed type constant velocity universal joint 1 is rotated, actually, the eight balls 4 sequentially pass through the range of the phase angle in the non-contact state. The same applies to the balls 4 located in the track grooves 7B, but since the track grooves 7B and the track grooves 7A are inclined in opposite directions, the balls 4 come off from the end of the outer joint member 2 on the opening side of the track grooves 7B and start to lose contact points with the track grooves 7BThe phase angle of the non-contact state is(for example,) The phase angle at which the balls 4 return to the end of the outer joint member 2 on the opening side of the track grooves 7B and start to contact the track grooves 7B is(for example, ). Therefore, as shown in fig. 8, the range M in which the balls 4 are disengaged from the track grooves 7A_ARange M of separation from track groove 7B_BWith some difference.

The reason described above will be described with reference to fig. 9. Fig. 9 is a developed view of the inner peripheral surface of the outer joint member showing a state in which the range in which the track grooves of the outer joint member of fig. 8 lose contact points with the torque transmission balls differs depending on the direction of inclination of the track grooves. In fig. 9, the right side of the center line in the vertical direction of the figure shows a state where the ball 4 is disengaged from the track groove 7A, and the left side shows a state where the ball 4 is disengaged from the track groove 7B. The open arrows in fig. 9 indicate the direction of the torque load from the inner joint member 3 to the outer joint member 2.

Since the track groove 7 is inclined with respect to the axial line, the track groove 7A contacts at a position shifted in the inward direction from the center Ob of the ball 4 and the track groove 7B contacts at a position shifted in the opening direction from the center Ob of the ball 4, according to the torque load direction in fig. 9. Therefore, the surface position 4ao of the ball 4 is caught by the end of the contact point trajectory CLo of the track groove 7A (the edge of the inlet chamfer 20), and becomes a phase angle at which the contact point is lostOn the other hand, the end of the contact point trajectory CLo (edge of the entrance chamfer 20) caught in the track groove 7B becomes a phase angle at which the contact point is lostThus, the phase angleAnda difference is generated.

Phase angle at which ball 4 returns to track groove 7 and starts to contactFor the same reason as described above, although the surface position 4ao of the ball 4 returns to the end of the contact point trajectory CLo of the track groove 7A (the edge of the inlet chamfer 20) and the phase angle at which the contact state is started becomes the phase angle(see fig. 8), on the other hand, the phase angle at which the contact point trajectory CLo of the track groove 7B returns to the end (edge of the entrance chamfer 20) and the contact state starts is set to be(refer to fig. 8). As a result, when the ball 4 rotates counterclockwise while obtaining the maximum operating angle, as shown in fig. 8, the range M in which the ball 4 loses the contact point with the track groove 7A_ALess than the range M of losing contact with the track groove 7B_B. Conversely, when the ball 4 rotates in the clockwise direction, the range M in which the ball loses the contact point with the track groove 7A is contrary to the above_AGreater than the range M of losing the contact point with the track groove 7B_B。

As described above, the fixed type constant velocity universal joint 1 of the present embodiment has a phase angle that moves toward the opening side of the track groove 7 of the outer joint member 2 when the maximum operating angle is obtainedThe adjacent balls 4 are separated from the end (inlet chamfer 20) of the outer joint member 2 on the opening side of the track groove 7 and lose contact with the track groove 7, and the balls 4 are separated from the end of the inner joint member 3 on the back side of the track groove 9 and lose contact with the track groove 9. However, the phase angle is set toAdjacent diametrically opposed phase anglesAs shown in fig. 6a, the balls 4 of (a) have contact points on the back side of the track grooves 7 of the outer joint member 2 and contact points on the opening side of the track grooves 9 of the inner joint member 3. This increases the number of balls 4 that receive the load, improves the balance of internal forces, and maintains strength and durability.

Next, a characteristic structure (2) of the fixed type constant velocity universal joint 1 according to the present embodiment, in which the end portion of the cage protrudes in the axial direction from the opening side end portion of the outer joint member in a state where the operating angle is 0 °, will be described with reference to fig. 10 to 11. Fig. 10 is a longitudinal sectional view illustrating dimensional characteristics of the fixed type constant velocity universal joint 1 shown in fig. 1a, and fig. 11 is a side view illustrating a state in which a retainer is incorporated into an outer joint member.

As shown in fig. 10, in the fixed type constant velocity universal joint 1 of the present embodiment, in order to increase the rigidity of the retainer 5, a socket-side end portion 5b having a cylindrical inner diameter surface 5c for fitting the inner joint member 3 into the retainer 5 is disposed on the back side of the outer joint member 2. The centers of curvature of the spherical outer peripheral surface 12 and the spherical inner peripheral surface 13 of the cage 5 are located at the joint center O, and the center Oc of the pocket 5a of the cage 5 coincides with the position in the axial direction of the joint center O in a state where the operating angle is 0 °. The retainer 5 of the fixed type constant velocity universal joint 1 according to the present embodiment has an asymmetrical shape with respect to the center Oc of the pocket 5 a.

Specifically, the axial dimension W of the outer joint member 2 in the back side direction with respect to the center Oc of the pocket 5a_EAxial dimension W of the opening side_FBecomes W_F＞W_EThe axial dimension W of the opening side_FThe setting is longer. And the axial dimension W of the opening side_FIs set longer than an axial dimension L1 from the coupling center O to the end surface of the outer coupling member 2 on the opening side (W)_F> L1). In other words, in the state of the working angle 0 °, the end of the cage 5 protrudes axially from the opening side end of the outer joint member 2. In the present specification and claims, "the end of the retainer axially protrudes from the opening side end of the outer joint member at an operating angle of 0 ° means as described above.

W as described above_FWith regard to setting of L1, a method of mounting the cage 5 into the outer joint member 2 in the fixed type constant velocity universal joint 1 of the cross track groove type according to the present embodiment was examined. When the retainer 5 is incorporated into the outer joint member 2, as shown in fig. 11, the retainer 5 is incorporated with its axis perpendicular to the axis of the outer joint member 2 and arranged in the vertical direction, with the spherical inner circumferential surface 6 of the outer joint member 2 spanning the concave pocket 5a of the retainer 5. Since the adjacent track grooves 7A and 7B are inclined in opposite directions, the cross track groove type has a portion 6S in which the spherical inner peripheral surface 6 is narrowed at the opening side end portion of the outer joint member 2, and therefore the length from the center Oc of the pocket 5a to the end surface of the cage 5 can be made asymmetrical.

The reason for this is that: as shown in fig. 11, since the portion 6S in which the spherical inner peripheral surface 6 is narrowed is present at the opening side end portion of the outer joint member 2, a margin is generated in the restriction between the retainer pocket width (the diameter of the balls) and the spherical inner peripheral surface width at the opening side end portion of the outer joint member (the retainer pocket width needs to be longer than the spherical inner peripheral surface width), and the insertion can be easily performed, and the insertion can be performed in an arrangement (a shift amount e) in which the axial center of the outer joint member 2 and the axial center of the retainer 5 are shifted.

HoldingAxial dimension W of opening side of tool 5_FA ratio W to an axial dimension L1 from the joint center O to an end surface of the outer joint member 2 on the opening side_Fthe/L1 is desirably set to 1.18 to 1.32. At W_FWhen the maximum operating angle is obtained,/L1 < 1.18, the largest portion of the open-side end surface of the cage 5 (phase angle) moves to the rear side of the spherical inner peripheral surface 6 of the outer joint member 2 ) The strength of the cage 5 cannot be expected to be improved at a position further to the rear side than the joint center O. In contrast, in the fixed type constant velocity universal joint 1 of the present embodiment, W represents_Fsince/L1 is 1.18 or more, as shown in the lower side of FIG. 6a, the open end surface portion of the cage 5 (phase angle) that moves the largest toward the rear side of the spherical inner peripheral surface 6 of the outer joint member 2) Since the retainer 5 is located at a position spaced apart from the coupling center O by the distance U toward the opening side, the strength of the retainer can be improved. On the other hand, in W_FThe axial dimension W of the open side of the cage 5 in the case of/L1 > 1.32_FBecomes too long and thus the cage cannot be fitted in the outer coupling member.

By the characteristic structure (2) of the fixed type constant velocity universal joint 1 of the present embodiment, that is, the end portion of the cage protrudes in the axial direction from the opening side end portion of the outer joint member in the state of the operating angle of 0 °, in the fixed type constant velocity universal joint of the cross track groove type, even when the cage 5 is subjected to an excessive load due to the balance breakdown of the force acting on the cage 5 when the ball loses the contact point with the track groove when used at an operating angle exceeding 50 °, the thickness of the cage 5 at the opening side end portion of the fixed type constant velocity universal joint 1 and the contact range of the cage 5 and the outer joint member 2 on the opening side with respect to the joint center O can be secured, and therefore the strength of the cage 5 can be improved.

As described above, the fixed type constant velocity universal joint 1 according to the present embodiment is configured to operate such that the balls lose their contact points when the maximum operating angle is obtained in the fixed type constant velocity universal joint of the cross track groove type, and therefore, even at a high operating angle at which the balls 4 lose their contact points with the track grooves 7 of the outer joint member 2, because the moment and force of the cage 5 due to the action of the balls 4 act in directions that are balanced with each other, the cage 5 is not greatly displaced from the plane of bisection, and the decrease in the constant velocity and the transmission efficiency and the change in the internal force can be minimized, and the structure (2) that can ensure the constant velocity and the transmission efficiency can be realized by combining the structure (1) that has favorable characteristics based on the fixed type constant velocity universal joint of the cross track groove type with the characteristics, and the structure (2) that can ensure the constant velocity and the transmission efficiency, A fixed type constant velocity universal joint which is durable and can improve the strength of a retainer.

In the above embodiment, the fixed type constant velocity universal joint 1 is exemplified in which the track grooves 7, 9 inclined in the circumferential direction of the outer joint member 2 and the inner joint member 3 of the fixed type constant velocity universal joint 1 include: first track groove portions 7a and 9a having arc-shaped track center lines Xa and Ya each having a coupling center O as a curvature center; the second track groove portions 7b and 9b have linear track center lines Xb and Yb, but the present invention is not limited to this, and a fixed constant velocity universal joint may be employed in which the entire axial regions of the track grooves 7 and 9 inclined in the circumferential direction of the outer joint member 2 and the inner joint member 3 are formed by an arc-shaped track center line X, Y having the joint center O as the curvature center.

The present invention is not limited to the above-described embodiments, and it is needless to say that the present invention can be implemented in various forms without departing from the scope of the present invention.

Description of reference numerals:

1 fixed constant velocity universal joint

2 outer coupling member

3 inside coupling component

3a end part

4 torque transmitting ball

5 holder

5a concave bag

5b recess side end part

6 spherical inner peripheral surface

7 raceway groove

7a first raceway groove portion

7b second track groove part

8 spherical outer peripheral surface

9 raceway groove

9a first raceway groove portion

9b second raceway groove portion

12 spherical outer peripheral surface

13 spherical inner peripheral surface

20 inlet chamfer

CLo contact point trajectory

CLi contact point trajectory

Axial dimension of L1 from the center of the coupling to the end face of the opening side

M plane

Axis of N coupling

O-shaped coupling center

Center of Ob ball

Center of the Oc concave pocket

P plane

Q plane

W interval

W_EAxial dimension in the inner side direction

W_FAxial dimension of opening side

Center line of X track

Center line of Xa orbit

Xb track center line

Y track center line

Ya track central line

Yb track center line

Maximum working angle of theta max

Phase angle

Phase angle

The phase angle.