Constant velocity universal joint and its manufacturing method

Abstract

The inner connecting member (20) has: a bottomed concave retaining portion (24) into which a sleeve (50) is pressed, the sleeve (50) supporting a cover (B) covering the opening; and a clearance portion (25) provided on a portion of the convex outer spherical surface (21) on the opening side, the clearance portion being formed with a diameter smaller than the outer diameter of the convex outer spherical surface (21) corresponding to the pressing range of the sleeve (50) pressed into the retaining portion (24).

Description

Technical Field

[0001] This invention relates to constant velocity universal joints and a method for manufacturing constant velocity universal joints. Background Technology

[0002] Conventional constant velocity universal joints, such as those disclosed in Patent Document 1, are known. In conventional constant velocity universal joints, a retaining sleeve is pressed into the inner engaging member. In this case, when the sleeve is pressed in, the convex outer spherical surface of the inner engaging member expands in diameter, sometimes interfering with the concave inner spherical surface of the cage, potentially hindering the smooth operation of the constant velocity universal joint. Therefore, in conventional constant velocity universal joints, contact with the expanded convex outer spherical surface of the inner engaging member is avoided by expanding a portion of the concave inner spherical surface of the cage into a cylindrical shape.

[0003] Prior art literature

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2013-194895 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] However, when the concave inner spherical surface of the cage is expanded into a cylindrical shape, as in conventional constant velocity universal joints, the contact area between the convex outer spherical surface of the inner engaging member and the concave inner spherical surface of the cage is reduced during operation. As a result, the following may occur: increased wear and wear dust generation associated with the reduced contact between the convex outer spherical surface of the inner engaging member and the concave inner spherical surface of the cage; and increased clearance between the convex outer spherical surface of the inner engaging member and the concave inner spherical surface of the cage, hindering the smooth operation of the constant velocity universal joint.

[0008] The purpose of this invention is to provide a constant velocity universal joint that can operate smoothly even when the sleeve is pressed in, through a simple structure, and a method for manufacturing the constant velocity universal joint.

[0009] Solution for solving the problem

[0010] The constant velocity universal joint comprises: an outer engaging member, formed as a bottomed cylindrical shape with an opening on one axial side and a bottom on the other axial side, having a plurality of outer locking grooves formed circumferentially along its inner periphery having a concave inner spherical surface; an inner engaging member, disposed inside the outer engaging member, having a plurality of inner locking grooves formed circumferentially along its outer periphery having a convex outer spherical surface; a plurality of locking members, rolling in the respective outer locking grooves and inner locking grooves, transmitting torque between the outer engaging member and the inner engaging member; and a cage. It is formed in a ring shape and disposed between the concave inner spherical surface of the outer connecting member and the convex outer spherical surface of the inner connecting member. It has a plurality of windows formed along the circumference to accommodate the locking member. The inner connecting member has: a bottom concave holding part for a sleeve to be pressed into on the opening side of the outer connecting member, the sleeve supporting the cover covering the opening; and a clearance part provided on a part of the convex outer spherical surface on the opening side, which has a diameter smaller than the outer diameter of the convex outer spherical surface corresponding to the pressing range of the sleeve pressed into the holding part.

[0011] Therefore, a clearance portion can be provided on a portion of the convex outer spherical surface of the inner engaging member of the constant velocity universal joint, and this clearance portion has a diameter smaller than the outer diameter of the convex outer spherical surface. Thus, when the sleeve is pressed into the retaining portion of the inner engaging member into the pressing range, even if the clearance portion, which has a smaller diameter than the convex outer spherical surface, expands in diameter, interference between the convex outer spherical surface of the inner engaging member and the clearance portion and the concave inner spherical surface of the retainer can be prevented when the engagement angle is other than 0 degrees.

[0012] Furthermore, by widening the clearance portion, the reduction in the contact area between the convex outer spherical surface of the inner engaging member and the concave inner spherical surface of the cage can be suppressed. This reduces wear associated with the contact between the convex outer spherical surface of the inner engaging member and the concave inner spherical surface of the cage, suppresses the generation of wear dust, and inhibits the increase in the gap between the convex outer spherical surface of the inner engaging member and the concave inner spherical surface of the cage, thus maintaining smooth operation of the constant velocity universal joint. Attached Figure Description

[0013] Figure 1 This is a cross-sectional view of a constant velocity universal joint with a drive shaft assembled, showing the engagement angle at 0 degrees.

[0014] Figure 2 This diagram illustrates the state of assembling a drive shaft into a constant velocity universal joint.

[0015] Figure 3 This is a sectional view used to illustrate the structure of the constant velocity universal joint.

[0016] Figure 4 It is a sectional view used to illustrate the structure of the inner joining member.

[0017] Figure 5 It is used for explanation Figure 4 A diagram showing the structure of the retaining part and the clearance part of the inner connecting member.

[0018] Figure 6 It is used to explain to Figure 4 A diagram showing the structure of the retaining part pressed into the sleeve.

[0019] Figure 7 This diagram illustrates the operation of a constant velocity universal joint when the engagement angle is other than 0 degrees. Detailed Implementation

[0020] (1. Structure of constant velocity universal joint 100)

[0021] like Figure 1 As shown, the constant velocity universal joint 100 in this example is a fixed-center ball-type (so-called ball cage type) constant velocity universal joint. Figure 2 As shown, the constant velocity universal joint 100 in this example is a structure for inserting and assembling the drive shaft S of a motor vehicle. Furthermore, the constant velocity universal joint 100 in this example is a structure for transmitting the rotation (and torque) of the drive shaft S to, for example, the differential of a vehicle (not shown in the figure).

[0022] like Figure 3 As shown, the constant velocity universal joint 100 mainly includes an outer engagement member 10, an inner engagement member 20, a plurality of balls 30 as locking members, a cage 40, and a sleeve 50. Furthermore, in this example, the constant velocity universal joint 100 has a cover B assembled (installed) between the inner periphery of the outer engagement member 10 and the outer periphery of the sleeve 50 to cover the opening of the outer engagement member 10.

[0023] In this example, the outer connecting member 10 is formed as follows: Figure 3 The left side (one side in the direction of axis O1) has an opening and in Figure 3 The right side (the other side in the direction of axis O1) has a bottomed cylindrical (cup-shaped) portion. The connecting portion 11 is integrally formed on the outer side of the bottom of the outer connecting member 10 in a manner extending in the direction of axis O1. Figure 3 (Right side). The connecting part 11 is connected to the vehicle's differential (not shown) in a manner that transmits rotation (and torque).

[0024] The inner periphery 12 of the outer engaging member 10 has a concave inner spherical surface 12a and an outer ball groove 12b serving as an outer locking groove. The concave inner spherical surface 12a is located in the central portion of the inner periphery 12 of the outer engaging member 10 in the direction of the axis O1. The concave inner spherical surface 12a is formed by a portion of a sphere drawn with the engaging center P as the center. That is, the part of the concave inner spherical surface 12a that is the longest radially from the axis O1 of the outer engaging member 10 is the central portion of the concave inner spherical surface 12a in the direction of the axis O1. That is, the concave inner spherical surface 12a tapers in diameter as it extends from the central portion in the direction of the axis O1 toward the opening side, and also tapers in diameter as it extends from the central portion in the direction of the axis O1 toward the bottom side.

[0025] The outer ball groove 12b is formed such that it extends along the axis O1 of the outer engaging member 10. Multiple outer ball grooves 12b are formed at equal intervals along the circumference of the outer engaging member 10. It should be noted that the direction of the axis O1 of the outer engaging member 10, i.e., the axial direction, refers to the direction of the rotation axis of the outer engaging member 10.

[0026] The outer periphery 13 of the outer connecting member 10 has a locking portion 13a formed on the opening side to lock the support member B2, which holds the cover body B1 of the cover B. It should be noted that the locking portion 13a has a receiving groove for receiving a sealing member such as an O-ring in order to liquid-tightly lock the support member B2.

[0027] like Figure 3 and Figure 4 As shown, the inner engaging member 20 is formed in a ring shape and disposed inside the outer engaging member 10. A convex outer spherical surface 21 is integrally formed along the axis O2 on the outer periphery of the inner engaging member 20. Specifically, the convex outer spherical surface 21 of the inner engaging member 20 is formed from a portion of a spherical surface drawn with the engagement center P as the center during torque transmission.

[0028] Furthermore, a plurality of inner ball grooves 22, which serve as inner locking grooves, are formed on the outer periphery of the inner engaging member 20 in a manner extending along the axis O2 of the inner engaging member 20. The number of inner ball grooves 22 is the same as that of the outer ball grooves 12b, and they are formed at equal intervals in the circumferential direction. Moreover, the inner ball grooves 22 are formed in a generally concave arc shape, specifically, a Gothic arc shape connecting two arcs.

[0029] Furthermore, an internal toothed spline 23 extending along the axis O2 is formed on the inner circumferential surface of the inner connecting member 20. The internal toothed spline 23 and the external toothed spline S1 of the drive shaft S assembled by insertion (see reference) Figure 1 and Figure 2) Engagement (gear engagement). In this case, the drive shaft S is inserted and connected to the inner engaging member 20 in such a way that its central axis coincides with the rotation axis of the inner engaging member 20. Here, the direction of the axis O2 of the inner engaging member 20 refers to the direction through the central axis of the inner engaging member 20, that is, the direction of the rotation axis of the inner engaging member 20.

[0030] In addition, such as Figure 4 As shown, the inner engaging member 20 has a retaining portion 24 that holds the sleeve 50 by pressing it in. The retaining portion 24 has an opening with a diameter smaller than the outer diameter of the sleeve 50, and as shown... Figure 5 As shown, it is formed into a bottomed concave shape with a defined pressing range H. Here, for example, before assembling the inner engaging member 20 to the retainer 40, the sleeve 50 is pressed into the retaining portion 24.

[0031] In addition, such as Figure 4 As shown, the end of the inner connecting member 20 on the opening side of the convex outer spherical surface 21 ( Figure 4 A clearance portion 25 is formed circumferentially on the left side. This clearance portion 25 is provided to suppress radial expansion of the convex outer spherical surface 21 caused by material flow due to the sleeve 50 being pressed into the retaining portion 24; more specifically, to create a diameter larger than the outer diameter of the convex outer spherical surface 21. Figure 5 As shown, the clearance portion 25 is provided in the convex outer spherical surface 21 within a range corresponding to the pressing range H provided along the axis O2. The clearance portion 25 is, for example, a chamfered portion extending the convex outer spherical surface 21 to the opening side at a ratio that results in a virtual surface K (in...). Figure 5 The small diameter is formed by a double-dotted line.

[0032] Therefore, when the sleeve 50 is pressed into the retaining portion 24, even if the relief portion 25 expands in diameter, it only expands to below the outer diameter of the convex outer spherical surface 21. Thus, by providing a relief portion 25 with a small diameter, there is no portion that protrudes beyond the outer diameter of the convex outer spherical surface 21 as the sleeve 50 is pressed in, and therefore, as will be described later, the inner engaging member 20 can rotate smoothly relative to the retainer 40.

[0033] like Figure 3 As shown, in this example, the multiple balls 30, which serve as locking members, are respectively clamped by the outer ball groove 12b of the outer engaging member 10 and the inner ball groove 22 of the inner engaging member 20, which is opposite to the outer ball groove 12b. Furthermore, each ball 30 engages with its respective outer ball groove 12b and its respective inner ball groove 22 in the circumferential direction (around the axis O1 of the outer engaging member 10 or around the axis O2 of the inner engaging member 20) in the rolling direction. Therefore, the balls 30 transmit torque between the outer engaging member 10 and the inner engaging member 20.

[0034] like Figure 3 As shown, the retainer 40 is formed in an annular shape. The outer peripheral surface of the retainer 40 is a convex outer spherical surface 41 corresponding to the concave inner spherical surface 12a of the outer engaging member 10. On the other hand, the inner peripheral surface of the retainer 40 is a concave inner spherical surface 42 corresponding to the convex outer spherical surface 21 of the inner engaging member 20. The retainer 40 is arranged with a predetermined gap between the concave inner spherical surface 12a of the outer engaging member 10 and the convex outer spherical surface 21 of the inner engaging member 20.

[0035] The length (width) of the retainer 40 along axis O1 (or axis O2) is longer than the concave inner spherical surface 12a of the outer connecting member 10 and longer than the length (width) of the inner connecting member 20 along axis O2. That is, as... Figure 1 As shown, when the engagement angle is 0 degrees, the convex outer spherical surface 41 of the retainer 40 is entirely aligned with the axis O1 of the concave inner spherical surface 12a of the outer engaging member 10, and the concave inner spherical surface 42 of the retainer 40 is entirely aligned with the axis O2 of the convex outer spherical surface 21 and the clearance portion 25 of the inner engaging member 20. Therefore, even when the engagement angle is not 0 degrees, the concave inner spherical surface 42 of the retainer 40 can still be aligned with the convex outer spherical surface 21 and the clearance portion 25 of the inner engaging member 20.

[0036] In addition, the retainer 40 has a plurality of windows 43. The plurality of windows 43 are rectangular through holes formed at equal intervals along the circumferential direction. The number of windows 43 in the retainer 40 is the same as the number of balls 30. And each window 43 houses one ball 30.

[0037] like Figure 6 As shown, the sleeve 50 is formed in a cylindrical shape. The sleeve 50 has a pressing part 51 on its outer peripheral surface, which is pressed into the retaining part 24 of the inner engaging member 20, and a retaining recess 52, which retains the inner peripheral part of the cover body B1 of the cover B (described later). Furthermore, the sleeve 50 has a drive shaft S inserted through its inner peripheral surface.

[0038] The press-in portion 51 has an outer diameter slightly larger than the inner diameter of the retaining portion 24. Furthermore, the press-in portion 51 is provided to be longer than the press-in range H corresponding to the depth of the retaining portion 24. Therefore, when the press-in portion 51 of the sleeve 50 is pressed into the retaining portion 24, the clearance portion 25 provided on the convex outer spherical surface 21 of the inner engaging member 20 expands in the radial direction to below the outer diameter of the convex outer spherical surface 21, as described above (press-in step of the manufacturing method).

[0039] The recess 52 maintains an outer diameter slightly larger than the inner diameter of the main body B1 of the protective cover. Furthermore, as... Figure 3As shown, the retaining recess 52 supports the cover body B1 in such a way that it is clamped between itself and the support member B2 of the cover B assembled on the outer peripheral surface of the outer engaging member 10. Thus, the retaining recess 52 liquid-tightly supports the cover body B1 in such a way that there is a sealing allowance between it and the inner peripheral surface of the cover body B1.

[0040] like Figure 3 As shown, the protective cover B has a disc-shaped protective cover body B1, a support member B2 supporting the protective cover body B1, and a clamp B3. The protective cover body B1 is formed using synthetic resin, rubber, or other known molding methods such as blow molding and injection molding. With the drive shaft S assembled, the protective cover body B1 is sealed by liquid-tightly covering the opening of the outer connecting member 10. The support member B2 supports the protective cover body B1 so that it cannot be detached by engaging the locking portion 13a formed on the outer periphery 13 of the outer connecting member 10. The clamp B3 secures the protective cover body B1 to the sleeve 50 with a sealing allowance.

[0041] An inner connecting member 20, a ball bearing 30, and a retainer 40 are arranged in the closed space formed by the outer connecting member 10 and the protective cover B (more specifically, the protective cover body B1). Furthermore, a lubricant such as grease is sealed into the closed space. This prevents the lubricant such as grease sealed in the closed space from leaking out of the interior of the outer connecting member 10 through the opening, and prevents water, mud, etc., from entering the interior of the outer connecting member 10 from the outside through the opening.

[0042] (2. Operation of constant velocity universal joint 100)

[0043] Next, the operation of the constant velocity universal joint 100 configured as described above will be explained. When the engagement angle is set to a value other than 0 degrees, such as... Figure 7 As indicated by the arrow, the inner engaging member 20 and the retainer 40 move toward the opening side of the outer engaging member 10 as the drive shaft S rotates. In this case, the retainer 40 moves toward the opening side along the concave inner spherical surface 12a of the outer engaging member 10, as... Figure 7 As shown, the convex outer spherical surface 21 and the clearance portion 25 of the inner connecting member 20 move towards the opening side along the concave inner spherical surface 42 of the retainer 40.

[0044] However, as described above, by pressing the sleeve 50 relative to the retaining portion 24 into the pressing range H, the clearance portion 25 is expanded to approximately the outer diameter of the convex outer spherical surface 21 below its outer diameter. In this case, in the inner engaging member 20, when moving to the opening side, as... Figure 7 As shown by the circle surrounded by the dotted line, with the aforementioned movement, in addition to the convex outer spherical surface 21, the clearance portion 25 can also contact the concave inner spherical surface 42 of the cage 40.

[0045] That is, with the sleeve 50 pressed in, the expanded diameter clearance portion 25 can be considered as part of the convex outer spherical surface 21. In addition to the convex outer spherical surface 21, the clearance portion 25 also slides in contact with the concave inner spherical surface 42 of the cage 40. In other words, in this case, compared to the case where only the convex outer spherical surface 21 and the concave inner spherical surface 42 of the cage 40 rub and slide, the clearance portion 25 can also rub and slide with the concave inner spherical surface 42 of the cage 40, thus increasing the contact area with the concave inner spherical surface 42.

[0046] Therefore, even with the clearance portion 25 provided in the inner engagement member 20, the contact area between the retainer 40 and the concave inner spherical surface 42 is not reduced. As a result, the increase in wear that would result from a reduction in the contact area can be suppressed. Thus, in the constant velocity universal joint 100, the generation of wear dust during operation can be reduced, and smooth operation can be maintained for a long time. Furthermore, by suppressing the increase in the gap between the convex outer spherical surface 21 and the clearance portion 25 of the inner engagement member 20 and the concave inner spherical surface 42 of the retainer 40, the generation of noise (e.g., rattling noise) during operation can also be suppressed.

[0047] Furthermore, in this example, the constant velocity universal joint 100 is pre-positioned with the sleeve 50 pressed into the retaining portion 24 and the protective cover B assembled on the sleeve 50 before assembling the drive shaft S. Therefore, when assembling the drive shaft S to the constant velocity universal joint 100, it is simply a matter of inserting the drive shaft S into the constant velocity universal joint 100 and assembling it. That is, after assembling the drive shaft S, it is not necessary to assemble, for example, the protective cover B. Therefore, the constant velocity universal joint 100 in this example can easily complete the assembly of the drive shaft S.

[0048] As can be seen from the above description, in the constant velocity universal joint 100 of this example, a clearance portion 25 can be provided on a portion of the convex outer spherical surface 21 of the inner engaging member 20. This clearance portion 25 has a diameter smaller than the outer diameter of the convex outer spherical surface 21. More specifically, it has a diameter smaller than the outer diameter of the virtual surface K obtained by extending the convex outer spherical surface 21 toward the opening. Therefore, when the sleeve 50 is pressed into the holding portion 24 of the inner engaging member 20 into the pressing range H, even if the clearance portion 25, which has a smaller diameter than the convex outer spherical surface 21, expands, interference between the convex outer spherical surface 21 and the clearance portion 25 of the inner engaging member 20 and the concave inner spherical surface 42 of the retainer 40 can be prevented when the engagement angle is other than 0 degrees.

[0049] Furthermore, by approximately expanding the diameter of the clearance portion 25 to the outer diameter of the convex outer spherical surface 21, the reduction in the contact area between the convex outer spherical surface 21 of the inner engaging member 20 and the concave inner spherical surface 42 of the retainer 40 can be suppressed. This reduces wear associated with the contact between the convex outer spherical surface 21 of the inner engaging member 20 and the concave inner spherical surface 42 of the retainer 40, and suppresses the generation of wear dust and the increase in the gap between the convex outer spherical surface 21 of the inner engaging member 20 and the concave inner spherical surface 42 of the retainer 40, thus maintaining smooth operation of the constant velocity universal joint 100 over a long period.

[0050] (3. Other)

[0051] In the example described above, the clearance portion 25 of the inner joining member 20 is formed by a straight chamfer on the convex outer spherical surface 21. However, the clearance portion 25 is not limited to being formed by a straight chamfer on the convex outer spherical surface 21; for example, it can also be formed by an arc-shaped chamfer on the convex outer spherical surface 21. Furthermore, the clearance portion 25 is not limited to being formed by a chamfer on the convex outer spherical surface 21; for example, it can be formed in a stepped shape, provided that the release strength of the pressed-in sleeve 50 can be sufficiently ensured.

[0052] Furthermore, in the example described above, the outer engaging member 10 has an outer ball groove 12b on its inner periphery 12 that forms an outer locking groove parallel to the direction of the axis O1. However, the outer ball groove, which serves as the outer locking groove, does not need to be formed parallel to the direction of the axis O1; it can be formed as a cross groove. It should be noted that when the outer ball groove is formed as a cross groove, the inner ball groove of the inner engaging member, which serves as the inner locking groove, is also formed as a cross groove. In this case, the same effect as in the example described above can be obtained.

[0053] Label Explanation

[0054] 10…Outer connecting member, 11…Connecting part, 12…Inner periphery, 12a…Concave inner spherical surface, 12b…Outer ball groove (outer locking groove), 13…Outer periphery, 13a…Locking part, 20…Inner connecting member, 21…Convex outer spherical surface, 22…Inner ball groove (inner locking groove), 23…Internal tooth spline, 24…Retaining part, 25…Allowing part, 30…Ball (locking member), 40…Cage, 41…Convex outer spherical surface, 42…Concave inner spherical surface, 43…Window part, 100…Constant velocity universal joint, B…Guard, B1…Guard body, B2…Support member, B3…Clamp, H…Press-in range, K…Virtual surface.

Claims

1. A constant velocity universal joint, comprising: The outer connecting member is formed as a bottomed cylindrical shape with an opening on one side of the axial direction and a bottom on the other side of the axial direction, and a plurality of outer locking grooves are formed along the circumferential direction on the inner periphery with a concave inner spherical surface. An inner engaging member is disposed inside the outer engaging member, and a plurality of inner locking grooves are formed circumferentially on the outer periphery having a convex outer spherical surface. Multiple locking members roll in the respective outer locking grooves and inner locking grooves, transmitting torque between the outer engaging member and the inner engaging member; and A retainer, formed in a ring shape, is disposed between the concave inner spherical surface of the outer engaging member and the convex outer spherical surface of the inner engaging member, and has a plurality of windows formed circumferentially to accommodate the locking member, wherein... The inner connecting member includes: A recessed retaining portion is provided for pressing a sleeve into the opening side of the outer engaging member, the sleeve supporting a cover that covers the opening; and A clearance portion is provided on a portion of the convex outer spherical surface on the opening side, and its diameter is smaller than the outer diameter of the convex outer spherical surface, corresponding to the pressing range of the sleeve pressed into the retaining portion. With the sleeve pressed into the pressing range of the retaining part, the diameter of the clearance part is less than or equal to the outer diameter of the convex outer spherical surface. The inner periphery of the retainer has a concave inner spherical surface corresponding to the convex outer spherical surface of the inner engaging member. A predetermined gap is provided between the convex outer spherical surface of the inner connecting member and the concave inner spherical surface of the retainer. With the sleeve pressed into the retaining part, and the inner engaging member and the retainer moving to the opening side of the outer engaging member, the enlarged clearance part slides into contact with the concave inner spherical surface of the retainer.

2. The constant velocity universal joint according to claim 1, wherein, The clearance portion is formed by chamfering the convex outer spherical surface.

3. A method for manufacturing a constant velocity universal joint, which is the method for manufacturing a constant velocity universal joint as described in claim 1, wherein, The manufacturing method includes a pressing step in which the sleeve is pressed into the retaining portion of the inner engaging member.

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