Fixed constant velocity joint

Abstract

To secure a constant velocity property and transmission efficiency, and to improve strength of a retainer in a fixed type constant velocity universal joint in an operation mode in which a ball loses a contact point in a region of a phase where it comes out from an outer joint member, when a high operation angle is taken.SOLUTION: In a fixed type constant velocity universal joint 1 composed of an outer joint member 2 provided with a plurality of track grooves 7 extended in an axial direction, an inner joint member 3 provided with a plurality of track grooves 9 extended in an axial direction, torque transmission balls 4 assembled between the opposed track grooves 7, 9, and a retainer 5 for retaining the torque transmission balls, the track grooves of the outer joint member are inclined in directions opposite to each other with respect to the adjacent track groove, the track grooves of the inner joint member are formed in a symmetrical mirror image with the track grooves of the outer joint member, the torque transmission balls moving to an opening side of the outer joint member have an operation mode to lose a contact point with an opening-side end portion in a maximum operation angle, and an end portion of the retainer is axially projected from the opening side end portion, when an operation angle is 0°.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a fixed type constant velocity universal joint. [Background technology]

[0002] Constant velocity universal joints that constitute the power transmission systems of automobiles and various industrial machines connect two shafts, one on the driving side and one on the driven side, in a manner that allows torque transmission, and can transmit rotational torque at a constant speed regardless of the operating angle of the two shafts. Constant velocity universal joints are broadly divided into fixed type constant velocity universal joints that allow only angular displacement, and sliding type constant velocity universal joints that allow both angular displacement and axial displacement. For example, in a drive shaft that transmits power from an automobile engine to driving wheels, a sliding type constant velocity universal joint is used on the differential side (inboard side), and a fixed type constant velocity universal joint is used on the driving wheel side (outboard side).

[0003] Important functions required of fixed type constant velocity universal joints for automobile drive shafts are a high working angle that matches the steering of the wheels, and the associated strength at high working angles. Conventionally, the maximum working angle has generally been 47° for Rzeppa type constant velocity universal joints (BJ type) and 50° for undercut free type constant velocity universal joints (UJ type), but there is an increasing demand for angles over 50° to improve the cornering and maneuverability of automobiles. To meet these demands, fixed type constant velocity universal joints of various structures have been proposed.

[0004] When a fixed type constant velocity universal joint is used at a high operating angle exceeding the conventional operating angle of 50°, 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 groove of the outer joint member becomes shorter, and the balls at a phase angle of around 0° come out of the track groove and lose their contact points. One method for extending the track groove of the outer joint member is to increase the pitch circle diameter (PCD) of the balls, but this would increase the outer diameter of the outer joint member and its weight.

[0005] 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 a combination of arcuate and tapered shapes, thereby suppressing an increase in the outer diameter and enabling a high operating angle.

[0006] In Patent Document 2, it is described that in a conventional fixed constant velocity universal joint, the functionality can be maintained even at the maximum operating angle by setting the ratio of the axial parallel distance between the ball center and the joint center at the phase angle (phase angle 0°) at which the torque transmission ball (hereinafter also simply referred to as the ball) moves the most toward the opening side of the outer joint member to the axial parallel distance between the ball center and the opening cone surface of the outer joint member to less than 2.9. Furthermore, it is described that when the ball protrudes from the track groove of the outer joint member until it loses its contact point at the operating angle, the functionality can be maintained by setting the ratio to less than 2.2. In addition, as a means for increasing the maximum operating angle, it is described that the ball can be prevented from falling off the cage and the outer joint member by setting the ratio of the axial distance between the ball center and the joint center at the phase (0° phase) at which the ball comes out most from the opening side end of the outer joint member at the maximum operating angle to the axial distance between the ball center and the opening cone surface of the outer joint member.

[0007] Patent Document 3 does not propose 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 proposes a highly efficient fixed type constant velocity universal joint in which the track center lines of the track grooves of the outer joint member and the inner joint member have arc-shaped portions with centers of curvature that are not offset in the axial direction with respect to the joint center O, and this arc-shaped track center line is inclined in opposite circumferential directions. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 4041641 [Patent Document 2] Patent No. 4885236 [Patent Document 3] JP 2013-104432 A Summary of the Invention [Problem to be solved by the invention]

[0009] The structure of Patent Document 1 suppresses an increase in the outer diameter of the outer joint member. However, since the track grooves of the outer joint member have a tapered shape toward the outer diameter side, the outer diameter of the outer joint member becomes large in order to ensure contact points between the balls and the track grooves at a high operating angle.

[0010] The structure of Patent Document 2 claims that when the balls protrude so far from the track grooves of the outer joint member that they lose their contact points at high operating angles, they remain in contact within the pockets of the cage (they are held within the pockets of the cage), and so function is not impaired. However, when the balls protrude so far from the track grooves of the outer joint member that they lose their contact points, the balance of forces acting on the cage is lost compared to when there are contact points, and so although the balls are held within the pockets of the cage, it was found that the strength of the cage is insufficient.

[0011] The fixed type constant velocity universal joint of Patent Document 3 has low torque loss and heat generation and is highly efficient, but there are unknown problems when it is used at a high operating angle exceeding the conventional operating angle (50°). This problem was investigated and verified as described below.

[0012] In view of the above problems, the present invention aims to provide a fixed constant velocity universal joint in which the maximum operating angle is set to an angle exceeding the conventional operating angle (50°) and in which, when a high operating angle is taken, the contact point is lost in the phase region (phase angle 0°) where the ball comes out of the outer joint member, and which can ensure constant velocity, transmission efficiency, and durability while also improving the strength of the cage. [Means for solving the problem]

[0013] The present inventors have conducted various studies and verifications on the above-mentioned problems, and have obtained the following findings and ideas, which have led to the present invention. (1) Imbalance of forces within the joint when the ball loses contact When a fixed constant velocity universal joint is used at a high operating angle exceeding the conventional operating angle (50°), as described above, the track groove of the outer joint member becomes shorter, and the balls at a phase angle of around 0° come off the track groove and lose their contact points. In the phase range where the balls lose their contact points with the track groove, the contact force between the balls and the track groove of the outer joint member and the track groove of the inner joint member, and the force acting from the balls to the cage are lost, and the other balls bear the load, resulting in an imbalance of internal forces. In particular, it has been found that the balance of forces within a constant velocity universal joint is significantly disrupted in a Rzeppa type constant velocity universal joint (BJ type) and an undercut free type constant velocity universal joint (UJ type) in which the center of curvature of the track groove is offset in the axial direction (hereinafter also referred to as the axial track offset type).

[0014] (2) Consideration of imbalance of forces within the joint In an axial track offset type fixed type constant velocity universal joint, the center of curvature of the track groove of the outer joint member is offset toward the opening side of the outer joint member with respect to joint center O, while the center of curvature of the track groove of the inner joint member is offset in the opposite direction from the center of curvature of the track groove of the outer joint member. The balls are disposed in a wedge-shaped space opening toward the opening side formed between the track groove of the outer joint member and the track groove of the inner joint member, and are positioned by a cage.

[0015] When torque is applied at a small angle, such as a common angle, each ball presses the cage in the same direction due to the component of the contact force between the track groove of the outer joint member and the track groove of the inner joint member, so that the spherical outer peripheral surface and the spherical inner peripheral surface of the cage come into strong contact with the spherical inner peripheral surface of the outer joint member and the spherical outer peripheral surface of the inner joint member, respectively. When torque is applied at a medium to high angle, the contact force between each ball and the track groove of the outer joint member and the track groove of the inner joint member varies in strength, and the force with which each ball presses the cage also varies in strength, so that the balance of the moment acting on the cage also shifts slightly from the bisecting plane. Furthermore, at a high operating angle where the balls lose their contact points with the track groove of the outer joint member, the number of balls that share the load decreases, so that the balance of the moment acting on the cage changes significantly, and the cage shifts significantly from the bisecting plane. It was considered that, in addition to the decrease in constant velocity and transmission efficiency, the strength of the cage may also be significantly reduced.

[0016] (3) Focus and verification From the above considerations, we focused on a fixed constant velocity universal joint of the intersecting track groove type, which has an excellent balance of forces acting from the balls to the cage. In a fixed constant velocity universal joint of the intersecting track groove type, the track grooves of the outer joint member are formed in an arc shape having a center of curvature with no axial offset, are inclined in the circumferential direction with respect to the axis of the joint, and adjacent track grooves are formed with the inclination directions opposite to each other, the raceway center line of the track groove of the inner joint member is mirror-symmetric with respect to the raceway center line of the track groove of the outer joint member, and balls are arranged at the intersections between the track grooves of the outer joint member and the track grooves of the inner joint member.

[0017] In the fixed constant velocity universal joint of the cross track groove type, when torque is applied at the common angle of small angles where the balls are in contact with the track grooves and at the range of medium to high angles, the balls basically push the cage in opposite directions in the adjacent track grooves, so the moment and force of the cage due to the action of the balls are balanced. In the range of medium to high angles, the contact force between each ball and the track groove of the outer joint member and the track groove of the inner joint member varies in strength, but compared to the conventional axial track offset type, the moment and force of the cage due to the action of the balls are balanced, so the cage is stable near the bisecting plane. Furthermore, even at high operating angles where the balls lose their contact points with the track grooves of the outer joint member, the moment and force of the cage due to the action of the balls still act in a balanced direction, so the cage does not deviate significantly from the bisecting plane, compared to the conventional axial track offset type.

[0018] From the above verification results, it was concluded that in the case of a cross track groove type fixed constant velocity universal joint, even when the balls lose their contact points with the track grooves of the outer joint member, the cage does not deviate significantly from the bisecting plane, and the deterioration of constant velocity and transmission efficiency and the change in internal force are kept to a minimum.

[0019] (4) New Ideas The present invention was arrived at from the idea of ​​basing a fixed constant velocity universal joint of the cross track groove type as a fixed constant velocity universal joint having an operating form in which the maximum operating angle is set to an angle exceeding the conventional operating angle (50°) and in which, when a high operating angle is used, the contact point is lost at the phase angle (near a phase angle of 0°) at which the ball comes out of the outer joint member.

[0020] As technical means for achieving the above-mentioned object, the present invention provides a fixed type constant velocity universal joint comprising an outer joint member having a plurality of track grooves formed on a spherical inner peripheral surface thereof and extending generally in the axial direction, and having an open side and a back side spaced apart in the axial direction, an inner joint member having a plurality of track grooves formed on a spherical outer peripheral surface thereof and extending generally in the axial direction, facing the track grooves of the outer joint member, torque transmission balls incorporated between the facing track grooves, and a cage which holds the torque transmission balls in pockets and has a spherical outer peripheral surface guided by the spherical inner peripheral surface of the outer joint member and a spherical inner peripheral surface guided by the spherical outer peripheral surface of the inner joint member, a track center line (X) of a track groove of the inner joint member at least has an arc-shaped portion having a center of curvature that is not offset in the 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 a joint axis (NN), and the inclination directions are opposite to each other in the track grooves adjacent in the circumferential direction, and a track center line (Y) of the track groove of the inner joint member is formed in mirror symmetry with respect to the track center line (X) of the mating track groove of the outer joint member with respect to a plane (P) including the joint center (O) and perpendicular to the joint axis (NN) in a state of an operating angle of 0°; The fixed type constant velocity universal joint is set so that a maximum operating angle during torque transmission exceeds 50°, when the maximum operating angle is reached, at least one of the torque transmission balls moving to an opening side of the track groove of the outer joint member loses its contact point with an opening side end of the track groove of the outer joint member, and when the operating angle is 0°, an end of the cage protrudes in the axial direction from the opening side end of the outer joint member, The retainer is located at the center (O C ) to the end face of the cage on the opening side of the outer joint member (W F ) is the center of the pocket (O C ) to the end face of the cage on the far side of the outer joint member (W E ) longer than It is characterized by the fact that

[0021] With the above configuration, the maximum operating angle is set to an angle that exceeds the conventional operating angle (50°), When the operating angle is taken, the ball comes out of the outer joint at a phase angle (near 0° phase angle). In a fixed constant velocity universal joint with a contactless operating form, it is possible to ensure constant velocity, transmission efficiency, and durability. To provide a fixed type constant velocity universal joint capable of improving the strength of a cage while maintaining the rigidity of the cage. can be done. The cage is inserted at the center of the cage pocket (O C ) to the end face of the cage on the opening side of the outer joint member (W F ) is the center of the pocket (O C ) to the end face of the cage on the far side of the outer joint member (W E ) is set to be longer, the strength of the cage can be improved.

[0022] Specifically, it is preferable that the orbit center line X of the track groove of the outer joint member is composed of an arc-shaped portion having a center of curvature that is not offset in the axial direction with respect to the joint center O, and a portion having a shape different from this arc-shaped portion, the arc-shaped portion and the portion with the different shape are smoothly connected at a connection point J, and the connection point J is located on the opening side of the outer joint member relative to the joint center O. This ensures constant velocity and transmission efficiency, and makes it possible to adjust the length of the track groove that is effective for ensuring a contact point and the size of the wedge angle at a high operating angle.

[0023] By having the differently shaped sections be linear, the effective track length can be increased.

[0024] The inner joint member has a cylindrical inner diameter surface for assembling the inner joint member into the cage. The stiffness of the cage can be increased by disposing the inlay side end portion of the cage on the rear side of the outer joint member.

[0026] The above cage Pocket center (O C ) to the outer joint member Opening side of the cage to the end face of the cage Axial dimension (W F ) to the axial dimension (L1) from the joint center (O) to the end face of the opening side of the outer joint member, W F It is preferable that / L1 is 1.18 to 1.32, which enables the retainer to be incorporated into the outer joint member and improves the strength of the retainer.

[0027] By setting the number of torque transmission balls to eight or more, a practical and compact fixed type constant velocity universal joint can be realized. Effect of the Invention

[0028] According to the present invention, in a fixed constant velocity universal joint in which the maximum operating angle is set to an angle exceeding the conventional operating angle (50°) and in which the contact point is lost at the phase angle (near 0° phase angle) at which the balls come out of the outer joint member when a high operating angle is taken, it is possible to realize a fixed constant velocity universal joint which can ensure constant velocity, transmission efficiency, and durability while also improving the strength of the cage. [Brief description of the drawings]

[0029] [Figure 1] FIG. 1(a) is a vertical sectional view of a fixed type constant velocity universal joint according to one embodiment of the present invention, and FIG. 1(b) is a right side view of FIG. [Diagram 2] FIG. 1(a) is a vertical sectional view of the outer joint member of FIG. 1(a), and FIG. [Diagram 3] FIG. 1(a) is a front view of the inner joint member of FIG. 1(a), and FIG. 1(b) is a right side view of FIG. [Figure 4] FIG. 2 is an enlarged cross-sectional view of one torque transmission ball and a track groove on line PP in FIG. [Diagram 5] FIG. 2 is a comparison diagram of longitudinal sections of the fixed type constant velocity universal joint of FIG. 1(a) and a conventional cross track groove type fixed type constant velocity universal joint having a maximum working angle. [Figure 6] FIG. 1(a) is a longitudinal sectional view of the fixed type constant velocity universal joint of FIG. 1(a) and FIG. 1(b) when the joint has the maximum operating angle, and FIG. [Figure 7] FIG. 7 is an enlarged longitudinal sectional view of part E in FIG. 6(a). [Figure 8] FIG. 1(b) is a diagram showing the range where the torque transmitting balls lose their contact points with the track grooves of the outer joint member at the maximum operating angle. [Figure 9]9 is a development view of the inner circumferential surface of the outer joint member shown in FIG. 8, illustrating a state in which the range in which the track grooves and the torque transmission balls of the outer joint member lose their contact points varies depending on the inclination direction of the track grooves. [Figure 10] FIG. 2 is a vertical sectional view for explaining dimensional features of the fixed type constant velocity universal joint shown in FIG. [Figure 11] FIG. 4 is a side view showing a state in which the cage is assembled into the outer joint member. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] A fixed type constant velocity universal joint according to one embodiment of the present invention will be described with reference to Figs. FIG. 1(a) is a vertical cross-sectional view of a fixed type constant velocity universal joint according to an embodiment of the present invention, and FIG. FIG. 2(a) is a vertical sectional view of the outer joint member of FIG. 1(a). FIG. 2(b) is a right side view of FIG. 2(a). FIG. 3(a) is a right side view of the inner joint portion of FIG. Material Positive 1(a), 1(b), and FIG. 3(b) is a right side view of FIG. 3(a). As shown in FIG. 1, the fixed type constant velocity universal joint 1 of the present embodiment is a fixed type constant velocity universal joint of a cross track groove type. The universal joint is made up of an outer joint member 2, an inner joint member 3, and a torque transmission ball (hereinafter, simply referred to as ball). The outer joint member 2 mainly comprises a ball 4 and a cage 5. The spherical inner peripheral surface 6 of the outer joint member 2 is Eight track grooves 7 are formed on the spherical outer peripheral surface 8 of the inner joint member 3. Eight track grooves 9 are formed in opposition to the track grooves 7. A cage 5 for holding balls 4 is disposed between the peripheral surface 6 and a spherical outer peripheral surface 8 of the inner joint member 3. The spherical outer peripheral surface 12 of the cage 5 is slidably fitted to the spherical inner peripheral surface 6 of the outer joint member 2. The spherical inner peripheral surface 13 of the cage 5 is slidably fitted to the spherical outer peripheral surface 8 of the inner joint member 3. do.

[0031] The centers of curvature of the spherical inner circumferential surface 6 of the outer joint member 2 and the spherical outer circumferential surface 8 of the inner joint member 3 are each formed at the joint center O, and the centers of curvature of the spherical outer circumferential surface 12 and the spherical inner circumferential surface 13 of the cage 5, which fit onto the spherical inner circumferential surface 6 of the outer joint member 2 and the spherical outer circumferential surface 8 of the inner joint member 3, respectively, are also located at the joint center O.

[0032] A female spline (the spline includes serrations; the same applies below) 11 is formed in the inner diameter hole 10 of the inner joint member 3, and a male spline 15 formed on the end of an intermediate shaft 14 (see FIG. 6(a)) is fitted into the female spline 11 to connect them so as to be able to transmit torque. The inner joint member 3 and the intermediate shaft 14 are positioned in the axial direction by a retaining ring 16.

[0033] As shown in Fig. 1(a), Fig. 1(b), Fig. 2(a), Fig. 2(b), Fig. 3(a) and Fig. 3(b), the eight track grooves 7 and 9 of the outer joint member 2 and the inner joint member 3 each extend generally in the axial direction. The track grooves 7 and 9 are inclined in the circumferential direction with respect to the axis line NN of the joint, and the inclination directions of the track grooves 7A, 7B and 9A, 9B adjacent to each other in the circumferential direction are opposite to each other. Eight balls 4 are disposed at each intersection of the paired track grooves 7A, 9A and 7B, 9B of the outer joint member 2 and the inner joint member 3. Fig. 1(a) shows the track grooves 7 and 9 in a state where the cross sections on the plane M shown in Fig. 2(a) and the plane Q shown in Fig. 3(a) are rotated to an inclination angle γ = 0°. In a state where the operating angle is 0°, the axis line NN of the joint is also the axis line No-No of the outer joint member and the axis line Ni-Ni of the inner joint member.

[0034] As an example of a configuration in the claims where "the track center line (X) of the track groove of the outer joint member is composed of an arc-shaped portion having a center of curvature that is not offset in the axial direction with respect to the joint center (O) and a portion having a shape different from this arc-shaped portion, the arc-shaped portion and the portion having a shape different from this arc-shaped portion are smoothly connected at a connection point (J), and the connection point (J) is located on the opening side of the outer joint member with respect to the joint center (O)", a fixed type constant velocity universal joint 1 of this embodiment will be described with reference to Fig. 1(a). Since the track center line X of the track groove of the outer joint member described above is composed of an arc-shaped portion having a center of curvature that is not offset in the axial direction with respect to the joint center O and a portion having a shape different from this arc-shaped portion, it is possible to ensure constant velocity, transmission efficiency, and durability, and to adjust the length of the track groove that is effective for ensuring a contact point and the size of the wedge angle at a high operating angle.

[0035] As shown in FIG. 1(a), the track groove 7 of the outer joint member 2 has a track center line X, and the track groove 7 is composed of a first track groove portion 7a having an arc-shaped track center line Xa with the joint center O as the center of curvature, and a second track groove portion 7b having a linear track center line Xb, and the track center line Xb of the second track groove portion 7b is smoothly connected as a tangent to the track center line Xa of the first track groove portion 7a. The linear portion is a portion having a shape different from the above-mentioned arc-shaped portion. The track center line Xa of the first track groove portion 7a means "an arc-shaped portion having a center of curvature that is not offset in the axial direction from the joint center (O)" that is at least provided in the track center line X of the track groove of the outer joint member in this specification and claims.

[0036] In order to accurately indicate the form and shape of the track grooves that extend generally in the axial direction, the term "track centerline" is used in this specification, which means the path traced by the center of a ball placed in the track groove when the ball moves along the track groove.

[0037] 1(a), the track groove 9 of the inner joint member 3 has a track center line Y, and the track groove 9 is composed of a first track groove portion 9a having an arc-shaped track center line Ya with the joint center O as the center of curvature, and a second track groove portion 9b having a linear track center line Yb, and the track center line Yb of the second track groove portion 9b is smoothly connected as a tangent to the track center line Ya of the first track groove portion 9a. By arranging the centers of curvature of the track center lines Xa and Ya of the first track groove portions 7a and 9a of the outer joint member 2 and the inner joint member 3 on the joint center O, i.e., the axis line NN of the joint, the track groove depth can be made uniform and processing can be facilitated.

[0038] 2(a) and 2(b), a state in which the track grooves 7 of the outer joint member 2 are inclined in the circumferential direction with respect to the axis line NN of the joint will be described in detail. The track grooves 7 of the outer joint member 2 are denoted by the symbols track grooves 7A and 7B due to the difference in the inclination direction. As shown in FIG. 2(a), a plane M including the orbit center line X of the track groove 7A and the joint center O is inclined at an angle γ with respect to the axis line NN of the joint. Although not shown, the track groove 7B adjacent to the track groove 7A in the circumferential direction has a plane M including the orbit center line X of the track groove 7B and the joint center O inclined at an angle γ with respect to the axis line NN of the joint in the opposite direction to the inclination direction of the track groove 7A.

[0039] In this 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.

[0040] Here, a supplementary explanation will be given regarding the reference numerals of the track grooves. Reference numeral 7 is used to refer to the entire track grooves of the outer joint member 2, with reference numeral 7a being assigned to the first track groove portion and reference numeral 7b being assigned to the second track groove portion. Furthermore, reference numerals 7A and 7B are used to distinguish between track grooves with different inclination directions, with reference numerals 7Aa and 7Ba being assigned to the first track groove portions and reference numerals 7Ab and 7Bb being assigned to the second track groove portions, respectively. Reference numerals are used in the same manner for the track grooves of the inner joint member 3 described later.

[0041] 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 axis line NN of the joint will be described in detail with reference to Fig. 3(a) and Fig. 3(b). The track grooves 9 of the inner joint member 3 are denoted by the symbols track grooves 9A and 9B according to the difference in the inclination direction. As shown in Fig. 3(a), a plane Q including the orbit center line Y of the track groove 9A and the joint center O is inclined by an angle γ with respect to the axis line NN of the joint. Although not shown, the track groove 9B adjacent to the track groove 9A in the circumferential direction has a plane Q including the orbit center line Y of the track groove 9B and the joint center O inclined by an angle γ with respect to the axis line NN of the joint in the opposite direction to the inclination direction of the track groove 9A. The inclination angle γ is preferably set to 4° to 12° in consideration of the operability of the fixed constant velocity universal joint 1 and the spherical width I of the track groove 9 of the inner joint member 3 on the closest side.

[0042] Also, similarly to the above-described outer joint member 2, in this embodiment, the entire area of ​​the track center line Y of the track groove 9A, i.e., 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 in mirror symmetry with the track center line X of the mating track groove 7 of the outer joint member 2, with respect to a plane P that includes the joint center O and is perpendicular to the joint axis NN in a state where the operating angle is 0°.

[0043] Based on FIG. 1(a), details of the track grooves as viewed from the longitudinal sections of the outer joint member 2 and the inner joint member 3 will be described. As described above, FIG. 1(a) shows the track grooves 7 and 9 in the plane M shown in FIG. 2(a) and the plane Q shown in FIG. 3(a) rotated to an inclination angle γ=0°. That is, the outer joint member 2 is a cross-sectional view of the track groove 7A of the outer joint member 2 in FIG. 2(a) as viewed from the plane M including the orbit center line X and the joint center O. Therefore, strictly speaking, it is not a longitudinal cross-sectional view in a plane including the joint axis line NN, but a cross-section inclined by an angle γ. FIG. 1(a) shows the track groove 7A of the outer joint member 2, but the track groove 7B has the same configuration as the track groove 7A except that the inclination direction is opposite to that of the track groove 7A, so a description thereof will be omitted. The track groove 7A is formed on the spherical inner peripheral surface 6 of the outer joint member 2 generally along the axial direction.

[0044] The track groove 7A has a track center line X, and the track groove 7A is composed of a first track groove portion 7Aa having an arc-shaped track center line Xa with the joint center O as the center of curvature (no axial offset), and a second track groove portion 7Ab having a linear track center line Xb. At an end J on the opening side 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 J is a connection point between the first track groove portion 7Aa and the second track groove 7Ab. Since the end J is located closer to the opening side than the joint center O, the linear track center line Xb of the second track groove portion 7Ab, which is connected as a tangent at the end J on the opening side of the track center line Xa of the first track groove portion 7Aa, is formed to approach the axis line NN of the joint as it moves toward the opening side. This increases the effective track length and prevents the wedge angle from becoming excessive.

[0045] As shown in FIG. 1(a), the straight line connecting the end J and the joint center O is defined as S. The joint axis N'-N' projected onto the plane M including the orbit center line X of the track groove 7A and the joint center O is inclined by γ with respect to the joint axis NN, and the angle formed by the straight line S and the perpendicular line K at the joint center O of the axis N'-N' is defined as β'. The perpendicular line K is on the plane P which includes the joint center O in the operating angle 0° state and is perpendicular to the joint axis NN. Therefore, the angle β formed by the straight line S with respect to the plane P in the present invention has the relationship sinβ=sinβ'×cosγ.

[0046] Similarly, the track grooves will be described in detail from the longitudinal section of the inner joint member 3 with reference to Fig. 1(a). The illustration is a sectional view of the track groove 9A of the inner joint member 3 in Fig. 3(a) as seen on a plane Q including the orbital center line Y and the joint center O. Therefore, strictly speaking, it is not a longitudinal sectional view on a plane including the joint axis line NN, but a cross section inclined by an angle γ. Fig. 1(a) shows the track groove 9A of the inner joint member 3, but the track groove 9B has the same configuration as the track groove 9A except that the inclination direction is opposite to that of the track groove 9A, so a description thereof will be omitted. The track groove 9A is formed on the spherical outer circumferential surface 8 of the inner joint member 3 generally along the axial direction.

[0047] The track groove 9A has a track center line Y, and the track groove 9A is composed of a first track groove portion 9Aa having an arc-shaped track center line Ya with the joint center O as the center of curvature (no axial offset), and a second track groove portion 9Ab having a linear track center line Yb. At the end J' on the far 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 J' is the connection point between the first track groove portion 9Aa and the second track groove 9Ab. Since the end J' is located on the far side of the joint center O, the linear track center line Yb of the second track groove portion 9Ab, which is connected as a tangent at the end J' on the far side of the track center line Ya of the first track groove portion 9Aa, is formed to approach the axis line NN of the joint as it goes farther. This increases the effective track length and prevents the wedge angle from becoming excessive.

[0048] As shown in FIG. 1(a), the straight line connecting the end J' and the joint center O is defined as S'. The joint axis N'-N' projected onto the plane Q including the orbit center line Y of the track groove 9A and the joint center O is inclined by γ with respect to the joint axis NN, and the angle formed by the 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 the plane P including the joint center O in the operating angle 0° state and perpendicular to the joint axis NN. Therefore, the angle β formed by the straight line S' with respect to the plane P including the joint center O in the operating angle 0° state is sinβ=sinβ'×cosγ.

[0049] Next, we will explain the angle β that the straight lines S and S' make with the plane P that includes the joint center O and is perpendicular to the joint axis NN when the working angle is 0°. When the working angle is θ, the ball 4 moves by θ / 2 with respect to the plane P that includes the joint center O of the outer joint part 2 and the inner joint part 3. The angle β is determined from 1 / 2 of the frequently used working angle, and the range of the track groove where the ball 4 contacts is determined within the frequently used working angle range. Here, we will define the frequently used common angle. The common angle of a joint is the working angle that occurs in a fixed constant velocity universal joint of a front drive shaft when the steering is in a straight-ahead position in a vehicle with one occupant on a horizontal, flat road surface. The common angle is usually selected and determined according to the design conditions of each vehicle model between 2° and 15°.

[0050] Due to the above angle β, in FIG. 1(a), the end J of the track center line Xa of the first track groove portion 7Aa is the center position of the ball when it moves most toward the opening side along the axial direction at the common angle. Similarly, in the inner joint member 3, the end J' of the track center line Ya of the first track groove portion 9Aa is the center position of the ball when it moves most toward the back side along the axial direction at the common angle. Since it is set in this way, within the range of the common angle, the ball 4 is located at 7Ba, 9Ba, which is inclined in the opposite direction to the first track groove portions 7Aa, 9Aa of the outer joint member 2 and the inner joint member 3, so that forces in opposite directions are applied from the ball 4 to the pocket portions 5a adjacent to each other in the circumferential direction of the cage 5, and the cage 5 is stabilized at the position of the joint center O (see FIG. 1(a)). As a result, the contact force between the spherical outer peripheral surface 12 of the retainer 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 retainer 5 and the spherical outer peripheral surface 8 of the inner joint member 3 are reduced, thereby suppressing torque loss and heat generation and improving durability.

[0051] In the high operating angle range, the balls 4 arranged in the circumferential direction are temporarily divided and positioned in the first track groove portions 7Aa, 9Aa and the second track groove portions 7Ab, 9Ab. Accordingly, contact forces are generated at the spherical contact portions 12, 6 between the cage 5 and the outer joint member 2 and the spherical contact portions 13, 8 between the cage 5 and the inner joint member 3. However, compared to the conventional axial track offset type, the moment of the cage 5 due to the action of the balls 4 and the force are balanced, so that the cage 5 is stable in the vicinity of the bisecting plane. In addition, since the high operating angle range is used less frequently, the fixed constant velocity universal joint 1 of this embodiment can suppress torque loss and heat generation in a comprehensive manner. Therefore, a fixed constant velocity universal joint with low torque loss and heat generation and high efficiency can be realized.

[0052] FIG. 4 is an enlarged cross-sectional view of one ball and the track groove on the line PP in FIG. 1(a). However, the track grooves 7 and 9 are shown in a state where the cross sections in the plane M shown in FIG. 2(a) and the plane Q shown in FIG. 3(a) are rotated to an inclination angle γ=0°. The cross-sectional shapes of the track groove 7 of the outer joint member 2 and the track groove 9 of the inner joint member 3 are elliptical or gothic arch shapes, and as shown in FIG. 4, the ball 4 is in angular contact with the track groove 7 of the outer joint member 2 at two points C1 and C2, and is in angular contact with the track groove 9 of the inner joint member 3 at two points C3 and C4. It is preferable that the angle (contact angle α) between the straight line passing through the center Ob of the ball 4 and each contact point C1, C2, C3, and C4 and the straight line passing through the center Ob of the ball 4 and the joint center O [see FIG. 1(a)] is 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 a circular contact.

[0053] The overall configuration of the fixed type constant velocity universal joint 1 of this embodiment is as described above. The fixed type constant velocity universal joint 1 of this embodiment is set to a maximum operating angle that significantly exceeds 50°, and its characteristic configuration is as follows. (1) In a cross track groove type fixed constant velocity universal joint, an operating mode has been achieved in which the balls lose their contact points when the maximum operating angle is achieved. (2) In addition, when the operating angle is 0°, the end of the cage protrudes in the axial direction from the opening side end of the outer joint member.

[0054] With the above configuration, in the cross track groove type fixed type constant velocity universal joint, an operating mode is established in which the balls lose their contact points when the maximum operating angle is taken. 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, the moment and force of the retainer 5 due to the action of the balls 4 act in a balanced direction, so that the retainer 5 does not deviate significantly from the bisecting plane, and the deterioration of constant velocity and transmission efficiency and the change in internal force can be kept to a minimum. This, combined with the characteristic configuration (2) in addition to the advantageous characteristic configuration (1) that the cross track groove type fixed type constant velocity universal joint has as its base, makes it possible to realize a fixed type constant velocity universal joint that can ensure constant velocity, transmission efficiency, and durability while also improving the strength of the retainer.

[0055] First, the characteristic configuration (1) of the fixed constant velocity universal joint 1 of this embodiment will be described with reference to FIG. 5. With respect to the center line (axis line of the joint) of FIG. 5, the upper half is a longitudinal sectional view of the fixed constant velocity universal joint 1 of this embodiment, and the lower half is a longitudinal sectional view of a fixed constant velocity universal joint of the cross track groove type using eight balls having a conventional maximum working angle. The fixed constant velocity universal joint 101 of the cross track groove type having a conventional maximum working angle shown in the lower half has a maximum working angle of 47°. The fixed constant velocity universal joint 101 mainly comprises 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 similar to the track grooves 7 and 9 of this embodiment, so only an outline will be described.

[0056] The track grooves 107, 109 of the outer joint member 102 and the inner joint member 103 of the fixed type constant velocity universal joint 101 are formed of first track groove portions 107a, 109a and second track groove portions 107b, 109b, respectively. The first track groove portions 107a, 109a have arc-shaped track center lines xa, ya, respectively, with the joint center O as the center of curvature (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 smoothly connected by a tangent at a connection point A on the opening side of the joint center O. The track center line ya of the first track groove portion 109a and the track center line yb of the second track groove portion 109b of the inner joint member 103 are smoothly connected by a tangent at a connection point A' on the far side.

[0057] As in the fixed type constant velocity universal joint 1 of this embodiment, the track grooves 107, 109 of the outer joint member 102 and the inner joint member 103 are inclined in the circumferential direction with respect to the axis line NN of the joint, and the track grooves 107, 109 adjacent in the circumferential direction are formed with the inclination directions opposite to each other. The angle β1 of the straight lines L, L' connecting the connection points A, A' and the joint center O with the plane P that includes the joint center O and is perpendicular to the axis line NN of the joint is set to be larger than the angle β of the fixed type constant velocity universal joint 1 of this embodiment.

[0058] The fixed type constant velocity universal joint 101 has an operating form in which the balls 104 are always kept in contact with the track grooves 107 of the outer joint member 102 up to the maximum operating angle (47°). The inlet chamfer 120 provided at the opening side end of the outer joint member 102 is set so that, at the maximum operating angle, the intermediate shaft does not interfere and the contact state between the balls 104 and the track grooves 107 of the outer joint member 102 is kept. For this reason, the axial dimension L2 from the joint center O of the outer joint member 102 to the end face on the opening side is set relatively long.

[0059] When a high operating angle exceeding 47° is required, the intermediate shaft interferes with the inlet chamfer 120. To avoid this, the inlet chamfer 120 is moved axially toward the joint center O and the inclination angle is appropriately increased. Accordingly, the axial dimension from the joint center O to the end face on the opening side of the outer joint member 102 must be shortened. The fixed type constant velocity universal joint 1 of this embodiment corresponds to this, and is set to a value significantly exceeding the conventional maximum operating angle. In the fixed type constant velocity universal joint 1 of this embodiment shown in the upper half of Fig. 5, the axial dimension L1 from the joint center O of the outer joint member 2 to the end face on the opening side is shorter than the axial dimension L2 from the joint center O to the end face on the opening side of the outer joint member 102 of the fixed type constant velocity universal joint 101 having the conventional maximum operating angle shown in the lower half.

[0060] The state when the fixed constant velocity universal joint 1 of this embodiment has the maximum operating angle will be described with reference to Fig. 6(a) and Fig. 6(b). Fig. 6(a) is a vertical cross-sectional view when the fixed constant velocity universal joint 1 has the maximum operating angle, and Fig. 6(b) is a right side view of Fig. 6(a). As described above, the length of the track groove 7 on the opening side of the outer joint member 2 is reduced, so that the operation mode of the fixed constant velocity universal joint 1 of this embodiment is such that, when the maximum operating angle θmax, which is significantly larger than the conventional one, is taken, as shown in Fig. 6(a), the ball 4 comes off from the end of the opening side of the track groove 7 of the outer joint member 2 and loses the contact point with the track groove 7. Also, the ball 4 comes off from the end of the inner side of the track groove 9 of the inner joint member 3 and loses the contact point with the track groove 9. As shown in Fig. 6(b), when the maximum operating angle θmax is taken, the center Ob of the ball 4 comes off the furthest from the opening side end of the track groove 7 of the outer joint member 2 at the position of phase angle 0° (φ0).

[0061] FIG. 6(a) shows a state in which the axis Ni-Ni of the inner joint member 3 (intermediate shaft 14) is bent to the maximum operating angle θmax (for example, 55°) on the paper surface of the figure with respect to the axis No-No of the outer joint member 2. The axis Nc-Nc of the cage 5 is inclined at a bisecting angle θmax / 2. Here, the phase angle 0° is defined as the circumferential angle position of the center Ob of the uppermost (vertex) ball 4 in the state in which the operating angle shown in FIG. 1(b) is 0°. In this specification and claims, the phase angle is shown in a manner that proceeds counterclockwise from the phase angle 0° (indicated as φ0 in FIG. 6(b), hereinafter also referred to as φ0). In addition, in this specification and claims, the maximum operating angle θmax is used to mean the maximum operating angle that the fixed constant velocity universal joint 1 can tolerate when in use.

[0062] In FIG. 6(a), the intermediate shaft 14 is shown in contact with the inlet chamfer 20 at the maximum operating angle. In reality, however, the inlet chamfer 20 is set in a shape and dimensions that leave a slight margin between it and the outer diameter surface of the intermediate shaft 14 when the maximum operating angle is taken, and the inlet chamfer 20 functions as a stopper surface when the intermediate shaft 14 exceeds the maximum operating angle.

[0063] As shown in Fig. 6(a), in the fixed type constant velocity universal joint 1 of this embodiment, when the maximum operating angle is taken, the ball 4 near the phase angle φ0 moving toward the opening side of the track groove 7 of the outer joint member 2 comes off the end (entrance chamfer 20) on the opening side of the track groove 7 of the outer joint member 2 and loses its contact point with the track groove 7, and the ball 4 comes off the end on the back side of the track groove 9 of the inner joint member 3 and loses its contact point with the track groove 9. Details of this state will be described with reference to Fig. 7, which is an enlarged view of part E in Fig. 6(a).

[0064] Surface positions 4ao, 4ai of the ball 4 when it contacts the inlet chamfer 20 and the track grooves 7, 9 formed at the end on the opening side of the outer joint member 2, and a surface position 4b of the ball 4 when it contacts the pocket 5a of the cage 5 are indicated by dashed lines. In addition, a contact point locus connecting contact points C2 (or C1, see FIG. 4) between the track groove 7 of the outer joint member 2 and the ball 4 in the axial direction is indicated as CLo, and a contact point locus connecting contact points C3 (or C4, see FIG. 4) between the track groove 9 of the inner joint member 3 and the ball 4 in the axial direction is indicated as CLi, and each is indicated by a dashed line. The contact point loci CLo, CLi are formed at positions away from the groove bottoms of the track grooves 7, 9.

[0065] The contact point locus CLo ends at the edge of the inlet chamfer 20 on the opening side of the outer joint member 2. The edge of the inlet chamfer 20 is the end of the track groove 7 of the outer joint member 2 on the opening side. The surface position 4ao of the ball 4 deviates from the end of the contact point locus CLo in the right direction in FIG. 7, and the ball 4 and the track groove 7 are in a non-contact state. About 1 to 2 of the 8 balls 4 lose their contact points with the track groove 7. These balls 4 are not involved in torque transmission. The contact point locus CLi of the track groove 9 of the inner joint member 3 ends at the end 3a on the far side. The surface position 4ai of the ball 4 deviates from the end of the contact point locus CLi in the left direction in FIG. 7, and the ball 4 and the track groove 9 are in a non-contact state. The deviation amount between the surface position 4ao of the ball 4 and the end of the contact point locus CLo of the track groove 7 of the outer joint member 2 is set to be larger than the deviation amount between the surface position 4ai of the ball 4 and the end of the contact point locus CLi of the track groove 9 of the inner joint member 3.

[0066] The surface position 4b of the ball 4 is secured in contact with the pocket 5a at a radial position just before the spherical outer circumferential surface 12 of the cage 5. The pocket 5a and the ball 4 are set to have an extremely slight interference fit, and since the ball 4 is not in contact with the track groove 9 of the inner joint member 3, there is no unavoidable interference between the track groove 9 and the ball 4. Therefore, the ball 4 is securely held in the pocket 5a, and the generation of abnormal noise is prevented. Even if the ball 4 should come out of the pocket 5a, the distance W between the edge of the entrance chamfer 20 of the track groove 7 and the edge of the pocket 5a of the cage 5 is set to have a relationship of Db>W with respect to the diameter Db of the ball 4, so that the ball 4 is prevented from falling out.

[0067] Next, the range in which the ball 4 deviates from the track groove 7, i.e., the range of the phase angle in which the ball 4 and the track groove 7 are in a non-contact state (hereinafter also simply referred to as the range), will be described with reference to Fig. 8. Fig. 8 is a diagram showing the range in which the ball 4 deviates from the track groove 7 of the outer joint member 2 at the maximum operating angle in Fig. 1(b). In Fig. 8, the range in which the ball 4 deviates from the track groove 7 of the outer joint member 2 is indicated by arrows. The leader lines of each arrow indicate the center Ob of the ball 4. In the fixed type constant velocity universal joint 1 of this embodiment, the track grooves 7A, 7B of the outer joint member 2 have an inclination angle γ in the circumferential direction with respect to the axis NN of the joint, and the track grooves 7A, 7B adjacent to each other in the circumferential direction are formed so as to be inclined in directions opposite to each other. Therefore, the phase angle range M in which the ball 4 deviates from the track groove 7A is 1 / 1000. A and the phase angle range in which it deviates from the track groove 7B is M B As shown in FIG. 8, the difference is slightly

[0068] The range in which the balls 4 deviate from the track groove 7 will be specifically described using one ball 4 positioned in the track groove 7A in Figures 6(a), 6(b) and 8 as an example. When 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 Figure 6(a) are kept constant, and the fixed constant velocity universal joint 1 is rotated counterclockwise from the phase angle φ0, the ball 4 deviates from the track groove 7A in Figure 8 at a phase angle φ2 just before the phase angle φ0. A (For example, φ2 AAt the position (phase angle φ0=336°), the ball 4 comes off the end of the track groove 7A on the opening side of the outer joint member 2, loses contact with the track groove 7A, and starts a non-contact state. Then, after passing the phase angle φ0, the phase angle A (For example, φ1 A = 24°), the ball 4 returns to the end of the track groove 7A on the opening side of the outer joint member 2 and starts to be in contact with the track groove 7A.

[0069] In the above, one ball 4 has been described as an example, but in reality, when the fixed constant velocity universal joint 1 is rotated, eight balls 4 pass through the phase angle range in sequence in which they are in a non-contact state. The same is true for the ball 4 located in the track groove 7B, but since the track groove 7B is formed with an inclination direction opposite to that of the track groove 7A, the ball 4 comes off the end of the opening side of the track groove 7B of the outer joint member 2, loses its contact point with the track groove 7B, and starts a non-contact state at a phase angle φ2 B (For example, φ2 B =333°), and the ball 4 returns to the end of the track groove 7B on the opening side of the outer joint member 2 and starts to come into contact with the track groove 7B. B (For example, φ1 B 8, the ball 4 is displaced from the track groove 7A within a range M A and the range that deviates from the track groove 7B is M B The above will be slightly different.

[0070] The above reasons will be further explained with reference to Fig. 9. Fig. 9 is a development of the inner circumferential surface of the outer joint member, showing the state in which the range in which the track grooves of the outer joint member in Fig. 8 lose their contact points with the torque transmission balls varies depending on the inclination direction of the track grooves. In Fig. 9, the right side of the center line in the vertical direction of the figure shows the state in which the ball 4 disengages from the track groove 7A, and the left side shows the state in which the ball 4 disengages from the track groove 7B. The outline arrow in Fig. 9 indicates the torque load direction from the inner joint member 3 to the outer joint member 2.

[0071] Since the track groove 7 is inclined with respect to the axis, the track groove 7A contacts the ball 4 at a position shifted toward the back side from the center Ob of the ball 4, and the track groove 7B contacts the ball 4 at a position shifted toward the opening side from the center Ob of the ball 4, in accordance with the torque load direction in FIG. 9. For this reason, the surface position 4ao of the ball 4 reaches the end of the contact point locus CLo of the track groove 7A (the edge of the entrance chamfer 20), and the phase angle φ2 at which the contact point is lost is A On the other hand, the phase angle φ2 at which the contact point is lost is reached at the end of the contact point locus CLo of the track groove 7B (the edge of the entrance chamfer 20). B Therefore, the phase angle φ2 A and φ2 B There will be a difference in.

[0072] The phase angle φ1 at which the ball 4 returns to the track groove 7 and starts the contact state is the same as that described above, so a development diagram is omitted. However, the phase angle φ1 at which the surface position 4ao of the ball 4 returns to the end of the contact point locus CLo of the track groove 7A (the edge of the entrance chamfer 20) and starts the contact state is the same as that described above. A (See FIG. 8), while the phase angle φ1 B As a result, when the maximum operating angle is taken and the bearing is rotated counterclockwise, as shown in FIG. 8, there is a range M where the ball 4 loses contact with the track groove 7A. A is the area M where the contact point with the track groove 7B is lost. B On the other hand, when the ball 4 is rotated clockwise, the above is reversed, and the ball 4 loses the contact point with the track groove 7A within the range M A is the area M where the contact point with the track groove 7B is lost. B Become bigger.

[0073] As described above, when the fixed type constant velocity universal joint 1 of this embodiment has the maximum working angle, the balls 4 near the phase angle φ0 moving toward the opening side of the track groove 7 of the outer joint member 2 are displaced from the end (entrance chamfer 20) on the opening side of the track groove 7 of the outer joint member 2 and lose their contact points with the track groove 7, and the balls 4 are displaced from the end on the back side of the track groove 9 of the inner joint member 3 and lose their contact points with the track groove 9. However, the balls 4 located at a phase angle (φ=180°) diametrically opposed to the vicinity of the phase angle φ0 are set to have a contact point on the back side of the track groove 7 of the outer joint member 2 and a contact point on the opening side of the track groove 9 of the inner joint member 3, as shown in FIG. 6(a). This increases the number of balls 4 receiving a load, improves the balance of internal forces, and maintains strength and durability.

[0074] Next, a characteristic configuration (2) of the fixed type constant velocity universal joint 1 of this embodiment, i.e., the end of the cage protruding in the axial direction from the opening side end of the outer joint member when the operating angle is 0°, will be described with reference to Figures 10 and 11. Figure 10 is a vertical cross-sectional view explaining the dimensional characteristics of the fixed type constant velocity universal joint 1 shown in Figure 1(a), and Figure 11 is a side view showing the state in which the cage is assembled into the outer joint member.

[0075] 10, in the fixed type constant velocity universal joint 1 of this embodiment, in order to increase the rigidity of the cage 5, a spigot side end portion 5b having a cylindrical inner diameter surface 5c for fitting the inner joint member 3 into the cage 5 is disposed at the rear side of the outer joint member 2. Furthermore, the centers of curvature of the spherical outer peripheral surface 12 and the spherical inner peripheral surface 13 of the cage 5 are each located at the joint center O, and when the operating angle is 0°, the center Oc of the pocket 5a of the cage 5 coincides with the joint center O in the axial direction. The cage 5 of the fixed type constant velocity universal joint 1 of this embodiment has an asymmetric shape with respect to the center Oc of the pocket 5a.

[0076] Specifically, the axial dimension of the outer joint member 2 in the rear direction relative to the center Oc of the pocket 5a is W E and the axial dimension of the opening side is W F By W F >WE The axial dimension of the opening side is W F The axial dimension W of the opening side is set to be long. F is set to be longer than the axial dimension L1 from the joint center O to the end face on the opening side of the outer joint member 2 (W F >L1). That is, when the operating angle is 0°, the end of the cage 5 protrudes in the axial direction from the opening side end of the outer joint member 2. In this specification and the claims, "when the operating angle is 0°, the end of the cage protrudes in the axial direction from the opening side end of the outer joint member" has the above meaning.

[0077] The above W F Regarding the setting of >L1, a method of assembling the cage 5 to the outer joint member 2 in the cross track groove type fixed constant velocity universal joint 1 of this embodiment was studied. When assembling the cage 5 to the outer joint member 2, as shown in Fig. 11, the axis of the cage 5 is perpendicular to the axis of the outer joint member 2 and arranged vertically, and the cage 5 is assembled in a state in which the pocket 5a of the cage 5 straddles the spherical inner circumferential surface 6 of the outer joint member 2. In the cross track groove type, adjacent track grooves 7A and 7B are inclined in opposite directions, and therefore there is a portion 6S where the spherical inner circumferential surface 6 is narrowed at the opening side end of the outer joint member 2, so that it is possible to make the length from the center Oc of the pocket 5a to the end face of the cage 5 asymmetric.

[0078] The reason for the above is that, as shown in FIG. 11, there is a portion 6S where the spherical inner circumferential surface 6 is narrowed at the opening end of the outer joint member 2, and therefore there is a margin in the restriction between the cage pocket width (diameter of the ball) and the spherical inner circumferential surface width at the opening end of the outer joint member (the cage pocket width needs to be longer than the spherical inner circumferential surface width), allowing for easy insertion, and the cage 5 can be inserted with the axis of the outer joint member 2 and the axis of the cage 5 offset (offset amount e).

[0079] Axial dimension W of the opening side of the cage 5 F and the ratio W of the axial dimension L1 from the joint center O to the end face of the opening side of the outer joint member 2 FIt is desirable to set / L1 to 1.18 to 1.32. F In the case of / L1<1.18, when the maximum operating angle is taken, the open end face portion of the cage 5 that has moved furthest to the inner side of the spherical inner peripheral surface 6 of the outer joint member 2 (phase angle φ=180°) is located on the inner side of the joint center O, and an improvement in the strength of the cage 5 cannot be expected. F Since / L1≧1.18, as shown in the lower part of FIG. 6(a), the opening side end face portion (phase angle φ=180°) of the cage 5 that has moved furthest to the innermost side of the spherical inner peripheral surface 6 of the outer joint member 2 is located at a distance U toward the opening side from the joint center O, so that the strength of the cage 5 can be improved. F When / L1>1.32, the axial dimension W of the opening side of the cage 5 F becomes too long, making it impossible to assemble the retainer to the outer joint member.

[0080] In the state where the fixed constant velocity universal joint 1 of this embodiment has a characteristic configuration (2) of an operating angle of 0°, the end of the retainer protrudes in the axial direction from the opening side end of the outer joint member. Therefore, even if a cross track groove type fixed constant velocity universal joint is used at an operating angle exceeding 50° and the balance of forces acting on the retainer 5 is lost when the balls lose their contact points with the track grooves, causing an excessive load to act on the retainer 5, the strength of the retainer 5 can be improved because the thickness of the retainer 5 at the opening side end of the fixed constant velocity universal joint 1 and the contact area between the retainer 5 and the outer joint member 2 can be secured on the opening side of the joint center O.

[0081] As described above, the fixed type constant velocity universal joint 1 of this embodiment is a cross track groove type fixed type constant velocity universal joint in which the balls lose their contact points when the maximum operating angle is taken. 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, the moment and force of the retainer 5 due to the action of the balls 4 act in a balanced direction, so that the retainer 5 does not deviate significantly from the bisecting plane, and the deterioration of constant velocity and transmission efficiency and the change in internal force can be kept to a minimum. This advantageous characteristic configuration (1) that the cross track groove type fixed type constant velocity universal joint has as its base, combined with the characteristic configuration (2), makes it possible to realize a fixed type constant velocity universal joint that can ensure constant velocity, transmission efficiency, and durability while improving the strength of the retainer.

[0082] In the above embodiment, the fixed type constant velocity universal joint 1 has been exemplified in which the circumferentially inclined track grooves 7, 9 of the outer joint member 2 and the inner joint member 3 are configured with the first track groove portions 7a, 9a having arc-shaped track center lines Xa, Ya with the joint center O as the center of curvature, and the second track groove portions 7b, 9b having linear track center lines Xb, Yb. However, the present invention is not limited to this, and the fixed type constant velocity universal joint may also be configured in such a way that the entire axial areas of the circumferentially inclined track grooves 7, 9 of the outer joint member 2 and the inner joint member 3 are formed with arc-shaped track center lines X, Y with the joint center O as the center of curvature.

[0083] The present invention is not limited to the above-described embodiments, and can of course be embodied in various other forms without departing from the spirit of the present invention. The scope of the present invention is indicated by the claims, and further includes the equivalent meanings set forth in the claims, and all modifications within the scope of the claims. [Explanation of symbols]

[0084] 1 Fixed constant velocity joint 2 Outer joint member 3 Inner joint member 3a end 4 Torque transmission ball 5 Cage 5a Pocket 5b Inlay side end 6 Spherical inner surface 7 Track groove 7a First track groove portion 7b Second track groove portion 8 Spherical outer surface 9 Track groove 9a first track groove portion 9b Second track groove portion 12 Spherical outer surface 13 Spherical inner surface 20 Entrance chamfer CLo contact point locus CLi contact point locus L1 Axial dimension from the center of the joint to the end face on the opening side M plane N Axis of joint O Joint center Center of the OB ball Oc Pocket Center P plane Q plane W Spacing W E Axial dimension in the rear direction W F Axial dimension of the opening side X orbit center line Xa Orbit center line Xb Orbit center line Y orbit center line Ya orbit center line Yb orbit center line θmax Maximum operating angle φ0 Phase angle φ1 Phase angle φ2 phase angle

Claims

1. A fixed type constant velocity universal joint comprising: an outer joint member having a plurality of track grooves formed on a spherical inner peripheral surface thereof and extending generally in the axial direction, and an open side and a back side spaced apart in the axial direction; an inner joint member having a plurality of track grooves formed on a spherical outer peripheral surface thereof and extending generally in the axial direction, facing the track grooves of the outer joint member; torque transmission balls incorporated between the facing track grooves; and a cage which holds the torque transmission balls in pockets and has a spherical outer peripheral surface guided by the spherical inner peripheral surface of the outer joint member and a spherical inner peripheral surface guided by the spherical outer peripheral surface of the inner joint member, wherein the track grooves of the outer joint member are aligned along a track center line ( a plane (M) including the track center line (X) and the joint center (O) is inclined with respect to the joint axis (N-N) and the track grooves adjacent in the circumferential direction are formed in opposite directions, and a track center line (Y) of the track groove of the inner joint member is formed in mirror symmetry with respect to the track center line (X) of the mating track groove of the outer joint member with respect to a plane (P) including the joint center (O) and perpendicular to the joint axis (N-N) in a state of an operating angle of 0°, the fixed type constant velocity universal joint is set so that a maximum operating angle during torque transmission exceeds 50°; an operating mode in which, when the maximum operating angle is achieved, at least one of the torque transmission balls moving to an opening side of the track groove of the outer joint member loses a contact point with an opening side end of the track groove of the outer joint member, In a state where the operating angle is 0°, an end of the cage protrudes in the axial direction from an opening side end of the outer joint member, The retainer is characterized in that the axial dimension (WF) of the retainer from the center (O C ) of the pocket of the retainer to the end face of the retainer on the opening side of the outer joint member is set to be longer than the axial dimension (W E ) of the retainer from the center (O C ) of the pocket to the end face of the retainer on the rear side of the outer joint member.

2. 2. The fixed type constant velocity universal joint according to claim 1, characterized in that a track center line (X) of the track groove of the outer joint member comprises an arc-shaped portion having a center of curvature that is not offset in the axial direction with respect to the joint center (O) and a portion having a shape different from that of the arc-shaped portion, the arc-shaped portion and the portion having a different shape are smoothly connected at a connection point (J), and the connection point (J) is located on the opening side of the outer joint member relative to the joint center (O).

3. 3. The fixed type constant velocity universal joint according to claim 2, wherein said portion having a different shape is linear.

4. The fixed type constant velocity universal joint according to any one of claims 1 to 3, characterized in that a spigot side end portion of the cage, which has a cylindrical inner diameter surface for assembling the inner joint member into the cage, is disposed on a rear side of the outer joint member.

5. The center of the pocket of the retainer (O C ) to the end face of the cage on the opening side of the outer joint member (W F ) to the axial dimension (L1) from the joint center (O) to the end face of the opening side of the outer joint member, W F 5. The fixed type constant velocity universal joint according to claim 1, wherein / L1 is 1.18 to 1.

32.

6. 6. A fixed type constant velocity universal joint according to claim 1, wherein the number of the torque transmission balls is eight or more.

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