Constant velocity universal joint

Abstract

To provide a constant velocity universal joint capable of suppressing deformation of balls by receiving a load from an inner ring, while suppressing deformation of a boundary part between an inner ring ball groove and an outer spherical surface of an inner ring, in a manner that it swells to a radial outer side with respect to the outer spherical surface.SOLUTION: An inner ring 3 of a constant velocity universal joint 1 is provided with chamfered portions 24 formed between an inner ring ball groove 22 and an outer spherical surface 21, the chamfered portion 24 includes a linear cross-sectional portion 41 positioned near the outer spherical surface 21 of the chamfered portion 24 and linearly formed on a cross section orthogonal to a moving locus Ta, Tb of a center of balls 4, and a circular arc cross-sectional portion 42 positioned near the inner ring ball groove 22 of the chamfered portion 24 and formed into a circular arc projection shape on the cross section orthogonal to the moving locus Ta, Tb of the center of the ball 4.SELECTED DRAWING: Figure 7

Description

[Technical Field]

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

[0002] In a constant velocity universal joint with a fixed joint center, when torque is transmitted between the inner and outer rings via balls, the area near the edge of the inner ring ball groove is subjected to a large load from the ball. The load from the ball near the edge of the inner ring ball groove can cause deformation at the boundary between the inner ring ball groove and the outer spherical surface of the inner ring, potentially causing the inner ring to bulge radially outward from the outer spherical surface. If the bulging deformation of the inner ring interferes with the cage, it can generate abnormal noise and affect the relative movement between the inner ring and cage.

[0003] Patent Document 1 describes providing a chamfered portion on the inner ring between the inner ring ball groove and the outer spherical surface of the inner ring in order to suppress deformation of the boundary between the inner ring ball groove and the outer spherical surface of the inner ring. Furthermore, the cross-sectional shape of the chamfered portion on the inner ring perpendicular to the axis is linear at the portion of the chamfered portion close to the inner ring ball groove, and arc-shaped at the portion of the chamfered portion close to the outer spherical surface. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 8-42585 Summary of the Invention [Problem to be solved by the invention]

[0005] It is known that the contact shape between the inner ring ball groove and the ball has a range of elliptical shapes. However, if the contact position of the ball is located near the edge of the inner ring ball groove, a portion of the contact ellipse formed by the ball may be missing. In the case of the chamfered portion shape described in Patent Document 1, the boundary between the inner ring ball groove and the linear portion of the chamfered portion is formed in an edge-like shape. If a portion of the contact ellipse formed by the ball is missing, the ball contacts the edge-like portion of the inner ring and is subjected to high pressure from the edge-like portion. This may cause the ball to deform, and the deformed portion of the ball may interfere with the cage, inner ring ball groove, or outer ring ball groove. This may result in abnormal noise or affect the relative motion of the inner ring, outer ring, cage, and ball.

[0006] The present invention has been made in consideration of these problems, and aims to provide a constant velocity universal joint that can suppress deformation of the boundary portion of the inner ring between the inner ring ball groove and the outer spherical surface so that it bulges radially outward from the outer spherical surface, while also suppressing deformation of the balls due to loads being applied from the inner ring. [Means for solving the problem]

[0007] The present invention First The embodiment is a constant velocity universal joint of a fixed joint center type, an outer ring having a plurality of outer ring ball grooves formed on an inner peripheral surface thereof and extending in the axial direction; an inner ring having a plurality of inner ring ball grooves formed on an outer peripheral surface thereof and extending in the axial direction; a plurality of balls engaging with the outer ring ball groove and the inner ring ball groove; a cage that is sandwiched between the inner spherical surface of the outer ring and the outer spherical surface of the inner ring, and that has retaining windows formed therein for retaining the plurality of balls; Equipped with the inner ring has a chamfered portion formed between the inner ring ball groove and the outer spherical surface, The chamfered portion is a linear cross-sectional portion of the chamfered portion located closer to the outer spherical surface and formed linearly in a cross section perpendicular to the movement path of the center of the ball; an arcuate cross-sectional portion of the chamfered portion that is located closer to the inner ring ball groove and that is formed in an arcuate convex shape in a cross section perpendicular to the movement locus of the center of the ball; Equipped with picture, The circumferential length of the chamfered portion is formed to be longer than the radial length of the chamfered portion. It is in a constant velocity universal joint. A second aspect of the present invention is a joint center fixed type constant velocity universal joint, comprising: an outer ring having a plurality of outer ring ball grooves formed on an inner peripheral surface thereof and extending in the axial direction; an inner ring having a plurality of inner ring ball grooves formed on an outer peripheral surface thereof and extending in the axial direction; a plurality of balls engaging with the outer ring ball groove and the inner ring ball groove; a cage that is sandwiched between the inner spherical surface of the outer ring and the outer spherical surface of the inner ring, and that has retaining windows formed therein for retaining the plurality of balls; Equipped with the inner ring has a chamfered portion formed between the inner ring ball groove and the outer spherical surface, The chamfered portion is a linear cross-sectional portion of the chamfered portion located closer to the outer spherical surface and formed linearly in a cross section perpendicular to the movement path of the center of the ball; an arcuate cross-sectional portion of the chamfered portion that is located closer to the inner ring ball groove and that is formed in an arcuate convex shape in a cross section perpendicular to the movement locus of the center of the ball; Equipped with The circumferential length of the chamfered portion is formed to vary depending on the axial position of the inner ring. It is in a constant velocity universal joint. A third aspect of the present invention is a joint center fixed type constant velocity universal joint, comprising: an outer ring having a plurality of outer ring ball grooves formed on an inner peripheral surface thereof and extending in the axial direction; an inner ring having a plurality of inner ring ball grooves formed on an outer peripheral surface thereof and extending in the axial direction; a plurality of balls engaging with the outer ring ball groove and the inner ring ball groove; a cage that is sandwiched between the inner spherical surface of the outer ring and the outer spherical surface of the inner ring, and that has retaining windows formed therein for retaining the plurality of balls; Equipped with the inner ring has a chamfered portion formed between the inner ring ball groove and the outer spherical surface, The chamfered portion is a linear cross-sectional portion of the chamfered portion located closer to the outer spherical surface and formed linearly in a cross section perpendicular to the movement path of the center of the ball; an arcuate cross-sectional portion of the chamfered portion that is located closer to the inner ring ball groove and that is formed in an arcuate convex shape in a cross section perpendicular to the movement locus of the center of the ball; Equipped with The outer ring is formed in a cup shape having a bottom surface, The outer ring ball groove and the inner ring ball groove are a first outer ring ball groove and a first inner ring ball groove formed so that an angle between the balls opens toward a cup opening of the outer ring when the joint angle is a predetermined angle; a second outer ring ball groove and a second inner ring ball groove formed so that an angle between the balls opens toward a cup bottom surface of the outer ring when the joint angle is the predetermined angle; Equipped with In the chamfered portions adjacent to the first inner ring ball groove and the second inner ring ball groove, respectively, the radial lengths of the chamfered portions are formed to be different lengths depending on the axial position of the inner ring, and are formed to be shorter at a position on a base side in the direction in which the included angle opens and longer at a position on a tip side in the direction in which the included angle opens. It is in a constant velocity universal joint. [Effects of the Invention]

[0008] By providing a chamfered portion on the inner ring of the above-described constant velocity universal joint between the inner ring ball groove and the outer spherical surface, deformation of the inner ring ball groove due to a load from the ball can be suppressed by bulging radially outward from the outer spherical surface of the inner ring. In particular, the chamfered portion has a linear cross-sectional portion located closer to the outer spherical surface and a circular cross-sectional portion located closer to the inner ring ball groove. In this way, the combination of a linear cross-sectional portion and a circular cross-sectional portion in the chamfered portion allows the circumferential length of the chamfered portion to be increased. As a result, even if the inner ring ball groove is deformed due to a load from the ball, bulging radially outward from the outer spherical surface of the inner ring can be further suppressed. Therefore, interference of the bulged portion of the inner ring with the cage can be suppressed, which can suppress the generation of abnormal noise due to interference and suppress adverse effects on the relative movement between the inner ring and the cage.

[0009] Furthermore, the arcuate cross-section of the chamfered portion is located closer to the inner ring ball groove. When the contact ellipse of the ball in the inner ring ball groove is missing, the inner ring ball groove deforms slightly, causing the arcuate cross-section of the chamfered portion to come into contact with the ball. When the inner ring ball groove deforms slightly, the ball comes into contact with the arcuate cross-section of the chamfered portion located closer to the inner ring ball groove, thereby reducing the pressure the ball receives from the inner ring. This prevents the ball from deforming due to the load from the inner ring.

[0010] As described above, according to the above aspect, it is possible to provide a constant velocity universal joint that can suppress deformation of the boundary portion of the inner ring between the inner ring ball groove and the outer spherical surface so that it bulges radially outward from the outer spherical surface, while also suppressing deformation of the balls due to load being applied from the inner ring. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is an axial cross-sectional view of a constant velocity universal joint. [Figure 2] 2 is a view of the constant velocity universal joint as seen from the outer ring cup opening side, as seen from the direction II in FIG. 1. FIG. [Figure 3] FIG. 2 is a view of the inner ring as seen from the axial direction. [Figure 4] 4 is an axial cross-sectional view of the first inner ring ball groove, taken along line IV-IV in FIG. 3. FIG. [Figure 5] 4 is an axial cross-sectional view of the second inner ring ball groove, and is a cross-sectional view taken along the line VV in FIG. 3. FIG. [Figure 6] FIG. 2 is a partially enlarged cross-sectional view of the inner ring taken along a direction perpendicular to the axis. [Figure 7] 7 is an enlarged cross-sectional view taken along line VII in FIG. 4, corresponding to part C in FIG. 6, and located on the cup opening side of the first inner ring ball groove. [Figure 8] 7 is an enlarged cross-sectional view taken along line VIII in FIG. 4, corresponding to part C in FIG. 6, and located on the cup bottom side of the first inner ring ball groove. [Figure 9] 10 is a graph showing the relationship between circumferential lengths Xa, Xb of the chamfered portion and radial lengths Ya, Yb of the chamfered portion in the axial direction of the chamfered portion. DETAILED DESCRIPTION OF THE INVENTION

[0012] (Embodiment 1) 1. Basic structure of constant velocity universal joint 1 The basic configuration of a constant velocity universal joint 1 will be described with reference to Figs. 1 and 2. The constant velocity universal joint 1 is used, for example, to transmit the driving force of a vehicle's power source to wheels. The constant velocity universal joint 1 in this embodiment is a joint with a fixed joint center, and uses balls 4 as torque transmission members. The constant velocity universal joint 1 includes an outer ring 2, an inner ring 3, a plurality of balls 4, and a cage 5.

[0013] The outer ring 2 is formed in a cylindrical shape. In this embodiment, the outer ring 2 is formed in a cup shape with a bottom surface. The outer ring 2 has an inner circumferential surface which has an inner spherical surface 11 centered on the joint center point O. Furthermore, a plurality of outer ring ball grooves 12 extending in the axial direction of the outer ring 2 are formed in the inner circumferential surface of the outer ring 2. In this embodiment, the plurality of outer ring ball grooves 12 are formed at equal intervals around the circumferential direction of the outer ring 2. The outer ring ball grooves 12 are formed, for example, in a Gothic arc shape. The surface between adjacent outer ring ball grooves 12 is formed by an inner spherical surface 11. In this embodiment, the outer ring 2 has six outer ring ball grooves 12 at equal intervals around the circumferential direction, and six of these are included as part of the inner spherical surface 11.

[0014] The inner ring 3 is formed in a cylindrical shape and is disposed inside the outer ring 2. The inner ring 3 has, on its outer peripheral surface, an outer spherical surface 21 centered on the joint center point O. Furthermore, a plurality of inner ring ball grooves 22 extending in the axial direction of the inner ring 3 are formed on the outer peripheral surface of the inner ring 3. In this embodiment, the plurality of inner ring ball grooves 22 are formed at equal intervals around the circumferential direction of the inner ring 3. The inner ring ball grooves 22 are formed, for example, in a Gothic arc shape. The surface between adjacent inner ring ball grooves 22 is formed by the outer spherical surface 21. In this embodiment, the inner ring 3 has six inner ring ball grooves 22 at equal intervals around the circumferential direction, and six of these are provided as part of the outer spherical surface 21. Furthermore, the inner ring 3 has splines 23 formed on its inner peripheral surface and is fitted onto the shaft 6.

[0015] The plurality of balls 4 are arranged between the corresponding outer ring ball grooves 12 and inner ring ball grooves 22. The balls 4 engage with the outer ring ball grooves 12 in the rotational direction of the outer ring 2, and engage with the inner ring ball grooves 22 in the rotational direction of the inner ring 3. Therefore, the plurality of balls 4 function as members that transmit torque between the outer ring 2 and the inner ring 3. Furthermore, the balls 4 are movable along the outer ring ball grooves 12 and the inner ring ball grooves. The balls 4 are located in positions based on the joint angle and the circumferential position of the outer ring 2 in the extension direction of the outer ring ball grooves 12 and the inner ring ball grooves 22. In other words, as the constant velocity universal joint 1 rotates, the balls 4 move back and forth along the outer ring ball grooves 12 and the inner ring ball grooves 22.

[0016] The cage 5 is formed in a cylindrical shape and is disposed between the inner spherical surface 11 of the outer ring 2 and the outer spherical surface 21 of the inner ring 3. The outer peripheral surface of the cage 5 is formed in an outer spherical shape corresponding to the inner spherical surface 11 of the outer ring 2, and the inner peripheral surface of the cage 5 is formed in an inner spherical shape corresponding to the outer spherical surface 21 of the inner ring 3. Furthermore, the cage 5 is formed with a plurality of retaining windows 31 for retaining each of the plurality of balls 4. The plurality of retaining windows 31 are formed at equal intervals in the circumferential direction of the cage 5.

[0017] 2. Detailed configuration of constant velocity universal joint 1 The detailed configuration of constant velocity universal joint 1 will be described with reference to Figures 1 and 2. In constant velocity universal joint 1 shown in Figures 1 and 2, an example is shown in which outer ring 2 has outer ring ball grooves 12a, 12b of different shapes formed therein, and inner ring 3 has inner ring ball grooves 22a, 22b of different shapes formed therein. However, constant velocity universal joint 1 may also have outer ring 2 having outer ring ball grooves 12 of the same shape formed therein, and inner ring 3 having inner ring ball grooves 22 of the same shape formed therein. In other words, constant velocity universal joint 1 can be used as a Birrfield joint (BJ), an undercut-free joint (UJ), or the like.

[0018] The outer ring 2 and inner ring 3 in this embodiment will be described in detail below. The outer ring 2 has first outer ring ball grooves 12a and second outer ring ball grooves 12b, which are different in shape. The first outer ring ball grooves 12a and second outer ring ball grooves 12b are arranged alternately in the circumferential direction. The inner ring 3 has first inner ring ball grooves 22a and second inner ring ball grooves 22b, which are different in shape. The first inner ring ball grooves 22a and second inner ring ball grooves 22b are arranged alternately in the circumferential direction. The first outer ring ball grooves 12a and the first inner ring ball grooves 22a face each other in the radial direction, and some of the balls 4 are arranged in set A of the first outer ring ball grooves 12a and the first inner ring ball grooves 22a. The second outer ring ball grooves 12b and the second inner ring ball grooves 22b face each other in the radial direction, and other balls 4 are arranged in set B of the first outer ring ball grooves 12a and the first inner ring ball grooves 22a.

[0019] Set A of first outer ring ball groove 12a and first inner ring ball groove 22a is formed so that when the joint angle is a predetermined angle (for example, 0° in this embodiment), the included angle α sandwiching ball 4 opens toward the cup opening (right side in FIG. 1) of outer ring 2. Set B of second outer ring ball groove 12b and second inner ring ball groove 22b is formed so that when the joint angle is a predetermined angle (for example, 0° in this embodiment), the included angle β sandwiching ball 4 opens toward the cup bottom surface of outer ring 2 (left side in FIG. 1).

[0020] The balls 4 act to push out the cage 5 in the direction in which the included angle widens. The included angle α between the first outer ring ball groove 12a and the first inner ring ball groove 22a and the included angle β between the second outer ring ball groove 12b and the second inner ring ball groove 22b open in opposite directions in the axial direction of the cage 5. With this configuration, the force of the balls 4 pushing out the cage 5 due to the included angle α and the force of the balls 4 pushing out the cage 5 due to the included angle β act to cancel each other out, thereby reducing the load with which the cage 5 is pressed against the inner spherical surface 11 of the outer ring 2 and the outer spherical surface 21 of the inner ring 3. As a result, energy loss associated with the balls 4 rolling in the outer ring ball grooves 12 and the inner ring ball grooves 22 can be reduced.

[0021] 3. Detailed configuration of inner ring 3 The detailed configuration of the inner ring 3 will be described with reference to Figs. 3 to 5. As shown in Fig. 3, the inner ring 3 has first inner ring ball grooves 22a and second inner ring ball grooves 22b formed alternately in the circumferential direction. Furthermore, the inner ring 3 has chamfered portions 24 formed between the outer spherical surface 21 and each of the inner ring ball grooves 22. In detail, a first chamfered portion 24a is formed between the outer spherical surface 21 and the first inner ring ball groove 22a, and a second chamfered portion 24b is formed between the outer spherical surface 21 and the second inner ring ball groove 22b.

[0022] 4, the first chamfered portion 24a is formed in at least the range of the first inner race ball groove 22a that comes into contact with the ball 4 in the axial direction of the inner race 3. However, the first chamfered portion 24a may be formed over the entire axial length of the inner race 3.

[0023] During torque transmission, the contact area between the ball 4 and the first inner ring ball groove 22a forms an ellipse at a position angled from the first inner ring ball groove 22a. When the ball 4 rolls in the first inner ring ball groove 22a, the movement locus Ta of the center of the ball 4 follows a locus as shown in Fig. 4. In this embodiment, the movement locus Ta of the center of the ball 4 is a straight line parallel to the central axis of the inner ring 3 on the cup bottom side and an arc on the cup opening side.

[0024] The groove depth of first inner ring ball groove 22a in a cross section perpendicular to the movement locus Ta of the center of ball 4 increases from the cup bottom side of outer ring 2 toward the cup opening side. That is, in FIG. 4 , when the center of ball 4 is located at Pa1, first inner ring ball groove 22a is deeper than when the center of ball 4 is located at Pa2. The shallower the groove depth of first inner ring ball groove 22a, the more likely the elliptical shape with which ball 4 contacts in first inner ring ball groove 22a will be chipped. That is, the shallower the groove depth of first inner ring ball groove 22a, the smaller the area with which ball 4 contacts, and the greater the pressure that first inner ring ball groove 22a receives from ball 4.

[0025] Here, the groove depth of first inner ring ball groove 22a can be defined, for example, as follows: In a cross section perpendicular to the movement locus Ta of the center of ball 4, the groove depth of first inner ring ball groove 22a is the distance between the groove bottom point of first inner ring ball groove 22a and the intersection point between a line passing through said groove bottom point and extending radially outward of inner ring 3 and an imaginary plane of outer spherical surface 21 of inner ring 3. The imaginary plane of outer spherical surface 21 is a spherical surface whose center is the center of outer spherical surface 21 and whose radius is the radius of curvature of outer spherical surface 21.

[0026] 5, the second chamfered portion 24b is formed in at least the range of the second inner race ball groove 22b that comes into contact with the ball 4 in the axial direction of the inner race 3. However, the second chamfered portion 24b may be formed over the entire axial length of the inner race 3.

[0027] During torque transmission, the contact area between the ball 4 and the second inner ring ball groove 22b forms an ellipse at a position angled from the second inner ring ball groove 22b. When the ball 4 rolls in the second inner ring ball groove 22b, the movement locus Tb of the center of the ball 4 follows a locus as shown in Fig. 5. In this embodiment, the movement locus Tb of the center of the ball 4 forms a straight line at an angle with the central axis of the inner ring 3 on the cup bottom side, and forms an arc on the cup opening side.

[0028] The groove depth of the second inner ring ball groove 22b in a cross section perpendicular to the movement locus Tb of the center of the ball 4 increases slightly from the cup opening side of the outer ring 2 toward the cup bottom side. In other words, in FIG. 5, when the center of the ball 4 is located at Pb1, the groove depth of the second inner ring ball groove 22b is slightly shallower than when the center of the ball 4 is located at Pb2. The shallower the groove depth of the second inner ring ball groove 22b, the more likely the elliptical shape with which the ball 4 contacts the second inner ring ball groove 22b will be chipped. In other words, the shallower the groove depth of the second inner ring ball groove 22b, the smaller the area with which the ball 4 contacts, and the greater the pressure that the second inner ring ball groove 22b receives from the ball 4. The groove depth of the second inner ring ball groove 22b is defined in the same way as the groove depth of the first inner ring ball groove 22a described above.

[0029] 4. Configuration of the first chamfered portion 24a and the second chamfered portion 24b The configurations of the first chamfered portion 24a and the second chamfered portion 24b will be described with reference to Figures 6 to 9. As shown in Figure 6, the first chamfered portion 24a has a linear cross-sectional portion 41 and an arcuate cross-sectional portion 42. Similarly to the first chamfered portion 24a, the second chamfered portion 24b also has a linear cross-sectional portion 41 and an arcuate cross-sectional portion 42.

[0030] As shown in Figure 6, the linear cross-sectional portion 41 of the first chamfered portion 24a is located closer to the outer spherical surface 21 of the first chamfered portion 24a, and is formed linearly in a cross section perpendicular to the movement locus Ta (shown in Figure 4) of the center of the ball 4. In particular, the linear cross-sectional portion 41 of the first chamfered portion 24a is formed adjacent to the outer spherical surface 21 of the inner ring 3. The linear cross-sectional portion 41 of the first chamfered portion 24a forms an angle φ with respect to a tangent to the outer spherical surface 21 at a position closest to the first chamfered portion 24a. This angle φ is set to, for example, 45° or less.

[0031] The arc cross-sectional portion 42 of the first chamfered portion 24a is located closer to the first inner ring ball groove 22a and is formed into a convex arc shape in a cross section perpendicular to the movement trajectory Ta (shown in FIG. 4) of the center of the ball 4. The radius of curvature of the arc cross-sectional portion 42 of the first chamfered portion 24a is radius R (shown in FIGS. 7 and 8). The arc cross-sectional portion 42 of the first chamfered portion 24a is formed adjacent to the linear cross-sectional portion 41 and is formed into a shape that smoothly connects to the linear cross-sectional portion 41. In other words, the boundary between the linear cross-sectional portion 41 and the arc cross-sectional portion 42 of the first chamfered portion 24a has a common tangent line. Furthermore, the arc cross-sectional portion 42 of the first chamfered portion 24a is formed adjacent to the first inner ring ball groove 22a.

[0032] Here, the manufacturing method for inner ring 3 involves forming it by forging, followed by cutting inner ring ball grooves 22. Therefore, in inner ring 3, outer spherical surface 21, first chamfered portion 24a, and second chamfered portion 24b are formed surfaces by forging, and first inner ring ball groove 22a and second inner ring ball groove 22b are machined surfaces by cutting.

[0033] By forging the inner ring 3, the arc cross-sectional portion 42 of the first chamfered portion 24a is formed into a shape that smoothly connects to the first inner ring ball groove 22a before cutting. However, because the first inner ring ball groove 22a is cut, the arc cross-sectional portion 42 of the first chamfered portion 24a has an uneven, angular portion at the boundary with the first inner ring ball groove 22a after cutting.

[0034] Next, the linear cross-sectional portion 41 of the second chamfered portion 24b is located closer to the outer spherical surface 21 of the second chamfered portion 24b, and is formed linearly in a cross section perpendicular to the movement locus Tb (shown in FIG. 5) of the center of the ball 4. In particular, the linear cross-sectional portion 41 of the second chamfered portion 24b is formed adjacent to the outer spherical surface 21 of the inner ring 3. The linear cross-sectional portion 41 of the second chamfered portion 24b forms an angle θ with respect to a tangent to the outer spherical surface 21 at a position closest to the second chamfered portion 24b. This angle θ is set to, for example, 45° or less.

[0035] The arc-shaped cross-sectional portion 42 of the second chamfered portion 24b is located closer to the second inner ring ball groove 22b and is formed into a convex arc-shaped cross section perpendicular to the movement trajectory Tb (shown in FIG. 5) of the center of the ball 4. The radius of curvature of the arc-shaped cross-sectional portion 42 of the second chamfered portion 24b is the same radius R as the radius of curvature of the arc-shaped cross-sectional portion 42 of the first chamfered portion 24a. The arc-shaped cross-sectional portion 42 of the second chamfered portion 24b is formed adjacent to the linear cross-sectional portion 41 and is formed into a shape that smoothly connects to the linear cross-sectional portion 41. In other words, the boundary between the linear cross-sectional portion 41 and the arc-shaped cross-sectional portion 42 of the second chamfered portion 24b has a common tangent line. Furthermore, the arc-shaped cross-sectional portion 42 of the second chamfered portion 24b is formed adjacent to the second inner ring ball groove 22b.

[0036] Then, by forging the inner ring 3, the arcuate cross-sectional portion 42 of the second chamfered portion 24b is formed into a shape that smoothly continues and connects to the second inner ring ball groove 22b before cutting. However, because the second inner ring ball groove 22b is cut, the arcuate cross-sectional portion 42 of the second chamfered portion 24b has a non-smooth angular portion at the boundary with the second inner ring ball groove 22b after cutting.

[0037] 7, at a position on the cup opening side of the outer ring 2, the first chamfered portion 24a has a circumferential length X1 and a radial length Y1. The circumferential length X1 is defined as the distance between a normal line that passes through a boundary point Q1 between the outer spherical surface 21 and the first chamfered portion 24a and a position on the outer spherical surface 21 closest to the first chamfered portion 24a, and a line that passes through a boundary point Q2 between the first inner ring ball groove 22a and the first chamfered portion 24a and is parallel to the normal line. The radial length Y1 is defined as the distance between a tangent line that passes through the boundary point Q1 and a position on the outer spherical surface 21 closest to the first chamfered portion 24a, and a line that passes through the boundary point Q2 and is parallel to the tangent line.

[0038] As shown in Fig. 7, the circumferential length X1 of the first chamfered portion 24a is longer than the radial length Y1 of the first chamfered portion 24a at a position on the cup opening side of the outer ring 2. Furthermore, in the first chamfered portion 24a, a boundary point Q3 between the linear cross-sectional portion 41 and the arcuate cross-sectional portion 42 is located near the center of the first chamfered portion 24a. Note that in Fig. 7, the first inner ring ball groove 22a1 indicated by the two-dot chain line is the shape of the first inner ring ball groove 22a formed by forging, and is the shape before cutting.

[0039] As shown in Fig. 8, at a position on the cup bottom side of the outer ring 2, the first chamfered portion 24a has a circumferential length X2 and a radial length Y2. The definitions of the circumferential length X2 and the radial length Y2 are the same as those of the circumferential length X1 and the radial length Y1. As shown in Fig. 8, at a position on the cup bottom side of the outer ring 2, the circumferential length X2 of the first chamfered portion 24a is longer than the radial length Y2 of the first chamfered portion 24a. Furthermore, in the first chamfered portion 24a, a boundary point Q3 between the linear cross-sectional portion 41 and the arc cross-sectional portion 42 is located near the center of the first chamfered portion 24a.

[0040] As shown in Figures 7 and 8, the first chamfered portion 24a is formed in a different shape depending on the axial position of the inner ring 3. However, as shown in Figures 7 and 8, in the first chamfered portion 24a, the radius of curvature R of the arcuate cross-sectional portion 42 is set to a constant value regardless of the axial position of the inner ring 3. However, in forging, forming variations of approximately ±10% occur in the radius of curvature R depending on the axial position. In the above, "set to a constant value" means that forming variations are included. Even if forming variations occur, the effects described below can be sufficiently obtained.

[0041] Referring to Fig. 9, the circumferential length Xa and the radial length Ya of the first chamfered portion 24a will be considered over the entire length. As shown in Fig. 9, the circumferential length Xa and the radial length Ya of the first chamfered portion 24a are formed to vary depending on the axial position of the inner ring 3. Specifically, the circumferential length Xa of the first chamfered portion 24a decreases from the cup bottom side toward the cup opening side of the outer ring 2. In other words, the circumferential length Xa of the first chamfered portion 24a is formed so that, in the axial direction of the inner ring 3, the circumferential length Xa is shorter at a deeper position of the first inner ring ball groove 22a than at a shallower position of the first inner ring ball groove 22a in a cross section perpendicular to the movement locus Ta (shown in Fig. 4) of the center of the ball 4. In other words, the circumferential length Xa of the first chamfered portion 24a is longer at the base side (cup bottom side) in the direction in which the included angle α (shown in FIG. 1) opens, and shorter at the tip side (cup opening side) in the direction in which the included angle α opens.

[0042] Furthermore, the radial length Ya of the first chamfered portion 24a varies so as to increase from the cup bottom side toward the cup opening side of the outer ring 2. In other words, the radial length Ya of the first chamfered portion 24a is formed so that, in the axial direction of the inner ring 3, the radial length Ya of the first inner ring ball groove 22a is longer at a deeper position than at a shallower position in a cross section perpendicular to the movement trajectory Ta (shown in FIG. 4) of the ball 4. In other words, the radial length Ya of the first chamfered portion 24a is shorter on the base side (cup bottom side) in the direction in which the included angle α (shown in FIG. 1) opens, and is longer on the tip side (cup opening side) in the direction in which the included angle α opens.

[0043] 9, the circumferential length Xa of the first chamfered portion 24a is always longer than the radial length Ya. However, the difference between the circumferential length Xa and the radial length Ya is larger toward the cup bottom surface side of the outer ring 2 and smaller toward the cup opening side.

[0044] On the other hand, like the first chamfered portion 24a, the second chamfered portion 24b is formed in a shape that varies depending on the axial position of the inner ring 3. However, in the second chamfered portion 24b, the radius of curvature R of the arcuate cross-sectional portion 42 is set to a constant value regardless of the axial position of the inner ring 3. As described above, forming variations occur in forging. Here, "set to a constant value" also means that forming variations occur. Even if forming variations occur, the effects described below can be sufficiently obtained.

[0045] As shown in FIG. 9, the circumferential length Xb and radial length Yb of the second chamfered portion 24b are formed to vary depending on the axial position of the inner ring 3. Specifically, the circumferential length Xb of the second chamfered portion 24b decreases from the cup opening side toward the cup bottom side of the outer ring 2. In other words, the circumferential length Xb of the second chamfered portion 24b is formed to be shorter in the axial direction of the inner ring 3 at a deeper position of the second inner ring ball groove 22b in a cross section perpendicular to the movement locus Tb (shown in FIG. 5) of the center of the ball 4 than at a shallower position. In other words, the circumferential length Xb of the second chamfered portion 24b is longer at a position on the base side (cup opening side) in the direction of the angle β (shown in FIG. 1) and shorter at a position on the tip side (cup bottom side) in the direction of the angle β.

[0046] Furthermore, the radial length Yb of the second chamfered portion 24b varies so as to increase from the cup opening side toward the cup bottom side of the outer ring 2. In other words, the radial length Yb of the second chamfered portion 24b is formed so that, in the axial direction of the inner ring 3, the radial length Yb is longer at a deeper position of the second inner ring ball groove 22b in a cross section perpendicular to the movement trajectory Tb (shown in FIG. 5) of the ball 4 than at a shallower position. In other words, the radial length Yb of the second chamfered portion 24b is shorter on the base side (cup opening side) in the direction of the included angle β (shown in FIG. 1) and longer on the tip side (cup bottom side) in the direction of the included angle β.

[0047] 5.Effects The constant velocity universal joint 1 of this embodiment described above exhibits the following effects. By providing the inner ring 3 of the constant velocity universal joint 1 with the chamfered portion 24 between the inner ring ball groove 22 and the outer spherical surface 21, even if the inner ring ball groove 22 is deformed under load from the balls 4, the inner ring 3 can be prevented from bulging radially outward from the outer spherical surface 21 of the inner ring 3. In particular, in the chamfered portion 24, the linear cross-sectional portion 41 is located closer to the outer spherical surface 21, and the arcuate cross-sectional portion 42 is located closer to the inner ring ball groove 22. In this way, the combination of the linear cross-sectional portion 41 and the arcuate cross-sectional portion 42 in the chamfered portion 24 can increase the circumferential lengths Xa and Xb of the chamfered portion 24. As a result, even if the inner ring ball groove 22 is deformed under load from the balls 4, the inner ring 3 can be prevented from bulging radially outward from the outer spherical surface 21 of the inner ring 3. Therefore, it is possible to prevent the raised portion of the inner ring 3 from interfering with the cage 5, suppress the generation of abnormal noise due to interference, and suppress adverse effects on the relative movement between the inner ring 3 and the cage 5.

[0048] Furthermore, in the chamfered portion 24, the arcuate cross-sectional portion 42 is located closer to the inner ring ball groove 22. When the contact ellipse of the ball 4 in the inner ring ball groove 22 is missing, the inner ring ball groove 22 is slightly deformed, causing the arcuate cross-sectional portion 42 of the chamfered portion 24 to come into contact with the ball 4. When the inner ring ball groove 22 is slightly deformed, the ball 4 comes into contact with the arcuate cross-sectional portion 42 of the chamfered portion 24 located closer to the inner ring ball groove 22, thereby reducing the pressure that the ball 4 receives from the inner ring 3. Therefore, deformation of the ball 4 due to the load received from the inner ring 3 can be suppressed.

[0049] Therefore, the boundary portion between the inner ring ball groove 22 and the outer spherical surface 21 in the inner ring 3 is prevented from deforming so as to bulge radially outward from the outer spherical surface 21, while also preventing the balls 4 from being deformed due to being subjected to a load from the inner ring 3.

[0050] Furthermore, in the chamfered portion 24, the linear cross-sectional portion 41 is formed adjacent to the outer spherical surface 21 of the inner ring 3, and the arcuate cross-sectional portion 42 is formed adjacent to the linear cross-sectional portion 41. Furthermore, the arcuate cross-sectional portion 42 is smoothly connected to the linear cross-sectional portion 41. This allows the desired shape of the chamfered portion 24 to be formed.

[0051] Furthermore, the circumferential lengths Xa and Xb of the chamfered portions 24a and 24b are longer than the radial lengths Ya and Yb of the chamfered portions 24a and 24b. By setting the chamfered portions 24a and 24b in this length relationship, the above-mentioned effects can be reliably achieved.

[0052] Furthermore, the circumferential lengths Xa, Xb of the chamfered portions 24a, 24b are formed to be different lengths depending on the axial position of the inner ring 3. Furthermore, the radial lengths Ya, Yb of the chamfered portions 24a, 24b are formed to be different lengths depending on the axial position of the inner ring 3. By forming the chamfered portions 24a, 24b in a shape that corresponds to the shape of the inner ring ball grooves 22a, 22b, the chamfered portions 24a, 24b can be formed in an appropriate shape to achieve the above-mentioned effects.

[0053] For example, the circumferential lengths Xa, Xb of the chamfered portions 24a, 24b are formed in such a way that, in the axial direction of the inner ring 3, the circumferential lengths Xa, Xb are shorter at deeper positions of the inner ring ball grooves 22a, 22b than at shallower positions in a cross section perpendicular to the movement loci Ta, Tb of the centers of the balls 4. Also, the radial lengths Ya, Yb of the chamfered portions 24a, 24b are formed in such a way that, in the axial direction of the inner ring 3, the circumferential lengths Ya, Yb are longer at deeper positions of the inner ring ball grooves 22a, 22b than at shallower positions in a cross section perpendicular to the movement loci Ta, Tb of the centers of the balls 4. The above-mentioned effects can be achieved by forming the chamfered portions 24a, 24b in a shape that corresponds to the groove depth of the inner ring ball grooves 22a, 22b.

[0054] Furthermore, the radius of curvature R of the arcuate cross-sectional portions 42 of the chamfered portions 24a, 24b is set to a constant value regardless of the axial position of the inner ring 3. When the contact ellipse of the ball 4 in the inner ring ball grooves 22a, 22b is missing, the inner ring ball grooves 22a, 22b are slightly deformed, causing the arcuate cross-sectional portions 42 of the chamfered portions 24a, 24b to come into contact with the ball 4. By setting the radius of curvature R of the arcuate cross-sectional portions 42 to a constant value, when the inner ring ball grooves 22a, 22b are slightly deformed, the ball 4 comes into contact with the arcuate cross-sectional portions 42 with a constant radius of curvature, thereby keeping the pressure that the ball 4 receives from the inner ring 3 within a desired small value range. Therefore, regardless of the position of the ball 4 in the inner ring ball grooves 22a, 22b, deformation of the ball 4 due to the load from the inner ring 3 can be suppressed.

[0055] In this embodiment, the constant velocity universal joint 1 has two different outer ring ball grooves 12a, 12b and two different inner ring ball grooves 22a, 22b. The radial lengths Ya, Yb of the chamfered portions 24a, 24b are formed to be different lengths depending on the axial position of the inner ring 3. Furthermore, the radial lengths Ya, Yb of the chamfered portions 24a, 24b are formed to be shorter at a position on the base side in the direction in which the included angles α, β open, and longer at a position on the tip side in the direction in which the included angles α, β open. Furthermore, the circumferential lengths Xa, Xb of the chamfered portions 24a, 24b are formed to be different lengths depending on the axial position of the inner ring 3. Furthermore, the circumferential lengths Xa, Xb of the chamfered portions 24a, 24b are formed to be longer at a position on the base side in the direction in which the included angles α, β open, and shorter at a position on the tip side in the direction in which the included angles α, β open. When the constant velocity universal joint 1 has this configuration, the chamfered portions 24a, 24b can be formed into a desired shape, and the above-mentioned effects can be achieved.

[0056] In addition, in this embodiment, the first inner ring ball groove 22a and the second inner ring ball groove 22b of the inner ring 3 are machined after being formed by forging, but the machining may be replaced with grinding, or the first inner ring ball groove 22a and the second inner ring ball groove 22b may be machined after being formed by forging, and then grinded. [Explanation of symbols]

[0057] 1 Constant velocity universal joint 2 outer ring 3. Inner circle 4 balls 5 Cage 11 Inner sphere 12, 12a, 12b Outer ring ball groove 21 Outer sphere 22, 22a, 22b Inner ring ball groove 24,24a,24b Chamfered part 31 Retaining window 41 Straight section 42 Arc cross section O Joint center point Ta,Tb ball center movement trajectory

Claims

1. A constant velocity universal joint with a fixed joint center, an outer ring having a plurality of outer ring ball grooves formed on an inner peripheral surface thereof and extending in the axial direction; an inner ring having a plurality of inner ring ball grooves formed on an outer peripheral surface thereof and extending in the axial direction; a plurality of balls engaging with the outer ring ball groove and the inner ring ball groove; a cage that is sandwiched between the inner spherical surface of the outer ring and the outer spherical surface of the inner ring, and that has retaining windows formed therein for retaining the plurality of balls; Equipped with the inner ring has a chamfered portion formed between the inner ring ball groove and the outer spherical surface, The chamfered portion is a linear cross-sectional portion of the chamfered portion located closer to the outer spherical surface and formed linearly in a cross section perpendicular to the movement path of the center of the ball; an arcuate cross-sectional portion of the chamfered portion that is located closer to the inner ring ball groove and that is formed in an arcuate convex shape in a cross section perpendicular to the movement locus of the center of the ball; Equipped with The circumferential length of the chamfered portion is formed to be longer than the radial length of the chamfered portion. Constant velocity universal joint.

2. 2. The constant velocity universal joint according to claim 1, wherein the circumferential length of said chamfered portion is formed to be different depending on the axial position of said inner ring.

3. A constant velocity universal joint with a fixed joint center, an outer ring having a plurality of outer ring ball grooves formed on an inner peripheral surface thereof and extending in the axial direction; an inner ring having a plurality of inner ring ball grooves formed on an outer peripheral surface thereof and extending in the axial direction; a plurality of balls engaging with the outer ring ball groove and the inner ring ball groove; a cage that is sandwiched between the inner spherical surface of the outer ring and the outer spherical surface of the inner ring, and that has retaining windows formed therein for retaining the plurality of balls; Equipped with the inner ring has a chamfered portion formed between the inner ring ball groove and the outer spherical surface, The chamfered portion is a linear cross-sectional portion of the chamfered portion located closer to the outer spherical surface and formed linearly in a cross section perpendicular to the movement path of the center of the ball; an arcuate cross-sectional portion of the chamfered portion that is located closer to the inner ring ball groove and that is formed in an arcuate convex shape in a cross section perpendicular to the movement locus of the center of the ball; Equipped with The circumferential length of the chamfered portion is formed to vary depending on the axial position of the inner ring. Constant velocity universal joint.

4. 4. The constant velocity universal joint according to claim 2 or 3, wherein the circumferential length of the chamfered portion is formed such that, in the axial direction of the inner ring, a position where the inner ring ball groove is deeper is shorter than a position where the inner ring ball groove is shallower in a cross section perpendicular to a moving locus of the center of the ball.

5. 5. The constant velocity universal joint according to claim 2, wherein the radial length of said chamfered portion is formed to be different depending on the axial position of said inner ring.

6. 6. The constant velocity universal joint according to claim 5, wherein the radial length of the chamfered portion is formed such that, in the axial direction of the inner ring, a position where the inner ring ball groove is deeper in a cross section perpendicular to a movement locus of the center of the ball is longer than a position where the inner ring ball groove is shallower.

7. 7. The constant velocity universal joint according to claim 2, wherein the radius of curvature of said arcuate cross-sectional portion is set to be constant regardless of the axial position of said inner ring.

8. The outer ring is formed in a cup shape having a bottom surface, The outer ring ball groove and the inner ring ball groove are a first outer ring ball groove and a first inner ring ball groove formed so that an angle between the balls opens toward a cup opening of the outer ring when the joint angle is a predetermined angle; a second outer ring ball groove and a second inner ring ball groove formed so that an angle between the balls opens toward a cup bottom surface of the outer ring when the joint angle is the predetermined angle; Equipped with 8. The constant velocity universal joint according to claim 1, wherein the radial length of the chamfered portion adjacent to each of the first inner ring ball groove and the second inner ring ball groove varies depending on the axial position of the inner ring, and is shorter at a position on a base side in the direction in which the included angle opens and longer at a position on a tip side in the direction in which the included angle opens.

9. A constant velocity universal joint with a fixed joint center, an outer ring having a plurality of outer ring ball grooves formed on an inner peripheral surface thereof and extending in the axial direction; an inner ring having a plurality of inner ring ball grooves formed on an outer peripheral surface thereof and extending in the axial direction; a plurality of balls engaging with the outer ring ball groove and the inner ring ball groove; a cage that is sandwiched between the inner spherical surface of the outer ring and the outer spherical surface of the inner ring, and that has retaining windows formed therein for retaining the plurality of balls; Equipped with the inner ring has a chamfered portion formed between the inner ring ball groove and the outer spherical surface, The chamfered portion is a linear cross-sectional portion of the chamfered portion located closer to the outer spherical surface and formed linearly in a cross section perpendicular to the movement path of the center of the ball; an arcuate cross-sectional portion of the chamfered portion that is located closer to the inner ring ball groove and that is formed in an arcuate convex shape in a cross section perpendicular to the movement locus of the center of the ball; Equipped with The outer ring is formed in a cup shape having a bottom surface, The outer ring ball groove and the inner ring ball groove are a first outer ring ball groove and a first inner ring ball groove formed so that an angle between the balls opens toward a cup opening of the outer ring when the joint angle is a predetermined angle; a second outer ring ball groove and a second inner ring ball groove formed so that an angle between the balls opens toward a cup bottom surface of the outer ring when the joint angle is the predetermined angle; Equipped with In the chamfered portions adjacent to the first inner ring ball groove and the second inner ring ball groove, respectively, the radial lengths of the chamfered portions are formed to be different lengths depending on the axial position of the inner ring, and are formed to be shorter at a position on a base side in the direction in which the included angle opens and longer at a position on a tip side in the direction in which the included angle opens. Constant velocity universal joint.

10. 10. The constant velocity universal joint according to claim 8 or 9, wherein the chamfered portion adjacent to the first inner ring ball groove has a circumferential length that varies depending on the axial position of the inner ring, and is formed so that the circumferential length is longer at a position on a base side in the direction in which the included angle opens and shorter at a position on a tip side in the direction in which the included angle opens.

11. the linear cross-sectional portion is formed adjacent to the outer spherical surface of the inner ring, 11. The constant velocity universal joint according to claim 1, wherein the arcuate cross-sectional portion is formed adjacent to the linear cross-sectional portion and adjacent to the inner ring ball groove.

12. 12. The constant velocity universal joint according to claim 1, wherein the arcuate cross-sectional portion is smoothly connected to the linear cross-sectional portion.

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