JP2010043667A - Fixed-type constant velocity universal joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve durability of a fixed-type constant velocity universal joint by controlling heat generation. <P>SOLUTION: The fixed-type constant velocity universal joint is provided with an outer ring 10, an inner ring 20, a ball 30, and a cage 40. Ball grooves 16 extended axially are circumferentially formed on the spherical-concave inner peripheral surface 14 of the outer ring 10 at predetermined spacing, and ball grooves 26 extended axially are circumferentially formed on the spherical-convex outer peripheral surface 24 of the inner ring 20 at predetermined spacing. The ball 30 is incorporated between the pair of the ball groove 16 of the outer ring 10 and the ball groove 26 of the inner ring 20, and the cage 40 retains the ball 30 by being placed between the inner peripheral surface 14 of the outer ring 10 and the outer peripheral surface 24 of the inner ring 20. The center O1 of the ball groove 16 of the outer ring 10 and the center O2 of the ball groove 26 of the inner ring 20 are positioned at the same position in the axial direction of the center O of the angle of the joint, and the ball groove 16 of the outer ring 10 and the ball groove 26 of the inner ring 20, both of which are paired, intersect with each other. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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

  Constant velocity universal joints used in power transmission devices for automobiles and various industrial machines are roughly classified into fixed types and sliding types. While the fixed type can only be angularly displaced, the sliding motion type is capable of not only angular displacement but also axial displacement (plunging). The present invention relates to a fixed type constant velocity universal joint.

  The fixed type constant velocity universal joint shown in FIG. 9 is a type called a Rzeppa type or a bar field type, and includes an outer ring 110, an inner ring 120, a plurality of balls 130, and a cage 140 as main components.

  The outer ring 110 is a disk type, and includes a through hole 112 for inserting a bolt and connecting with a flange, and is connected to a driving shaft or a driven shaft so as to be able to transmit torque. The inner peripheral surface 114 of the outer ring 110 is concave spherical, and ball grooves 116 extending in the axial direction are formed at equal intervals in the circumferential direction of the inner peripheral surface. A seal plate 118 is attached to the left end surface of the outer ring 110 in FIG.

  The inner ring 120 is connected to a shaft (driven shaft or driving shaft) 158 through a spline (or serration, the same applies hereinafter) hole 158 formed in the shaft center portion so that torque can be transmitted. The outer peripheral surface 124 of the inner ring 120 has a convex spherical shape, and ball grooves 126 extending in the axial direction are formed at equal intervals in the circumferential direction of the outer peripheral surface 124.

  The ball groove 116 of the outer ring 110 and the ball groove 126 of the inner ring 120 make a pair, and one ball 130 is incorporated between each pair of ball grooves 116 and 126.

  The cage 140 is interposed between the outer ring 110 and the inner ring 120, the outer peripheral surface 142 has a convex spherical shape that matches the inner peripheral surface 114 of the outer ring 110, and the inner peripheral surface 144 matches the outer peripheral surface 124 of the inner ring 120. Concave spherical shape. Pockets 146 are formed at predetermined intervals in the circumferential direction of the cage 140, and one ball 130 is accommodated in each pocket 146. Therefore, all balls 130 are held in the same plane by the cage 140. The pocket 146 penetrates the cage 140 in the radial direction, and the ball 130 accommodated in the pocket 146 faces the ball groove 116 of the outer ring 110 on the outer diameter side of the cage 140, and the ball of the inner ring 120 on the inner diameter side of the cage 140. It faces the groove 126.

  In general, the boot 150 is used in order to prevent leakage of lubricating grease and to prevent water and foreign matter from entering from the outside. The boot 150 includes a boot body 152 and a boot adapter 154 made of a flexible material. A small diameter portion of the boot body 152 is attached to a shaft 158 and fastened with a boot band 156. The large diameter portion of the boot main body 152 is wound around and fixed to the small diameter end portion of the boot adapter 154. The large-diameter end of the boot adapter 154 is attached to the end surface of the outer ring 110 on the side opposite to the seal plate 118 described above. The seal plate 118 and the boot adapter 154 are fixed between flanges (not shown) with the outer ring 110 sandwiched from both sides.

The above-mentioned Barfield type is known as a fixed type constant velocity universal joint used for an automobile propeller shaft. Conventionally, a bar-field type using six balls has been generally used, but in recent years, various proposals have been made for light weight, compactness, or high performance (Patent Documents 1 and 2). .
Japanese Patent No. 3859264 Japanese Patent No. 3300633

  In order to reduce the diameter of the conventional barfield type using six balls for the purpose of higher performance and compactness, and to suppress the decrease in load capacity per ball, Patent Document 1) By making the ball grooves of the inner ring and the outer ring inclined with respect to the axis, spiraling, or making adjacent ball grooves symmetrical, the contact force between the ball grooves of the inner ring and the outer ring and the ball is increased. There has been a proposal (Patent Document 2) that can be suppressed and durability is improved.

In the case of the former (Patent Document 1), in order to smoothly operate the cage 140, an axial offset is provided as shown in FIG. That is, in the plane including the axis of the joint, the center of the inner peripheral surface 114 of the outer ring 110 and the center of the outer peripheral surface 124 of the inner ring 120 both coincide with the angular center O of the joint, but the center of the ball groove 116 of the outer ring 110 O ₁ and the center O ₂ of the ball groove 126 of the inner ring 120 are offset by an equal distance F in the axial direction on opposite sides from the angular center O of the joint. As a result, the paired ball grooves 116 and 126 have a wedge-shaped cross-sectional shape that is reduced from one to the other in the axial direction. The symbol τ represents the wedge angle.

  The locus of contact between the ball 130 and the ball grooves 116 and 126 is indicated by a broken line. Due to the action of the wedge angle τ, the ball 130 receives a force W in the direction in which the wedge is opened, so that the ball 130 pushes against the wall surface of the pocket 146 and operates the cage 140 smoothly. As can be understood from FIG. 10, the wedge angle τ is an angle formed by a tangent at a contact portion between the ball groove 116 of the outer ring 110 and the ball 130 and a tangent at a contact portion between the ball groove 126 of the inner ring 120 and the ball 130. Can be defined.

  As described above, the axial offset is important in operating the cage 140, but since the directions of the wedge angles τ formed due to the axial offset are all the same, the force W is always only in one direction. Will occur. As a result, the inner peripheral surface 114 of the outer ring 110 and the outer peripheral surface 142 of the cage 140 and the outer peripheral surface 124 of the inner ring 120 and the inner peripheral surface 144 of the cage 140 are in contact with each other, and heat is generated when the load is high or when rotating at high speed. Causes and adversely affects durability.

  Even in the latter (Patent Document 2), an axial offset is provided, but the force applied to the cage decreases as the ball contact force of the outer ring and the inner ring decreases, but when a large load is applied as in the conventional type, During high-speed rotation, heat is generated due to contact between the outer peripheral surface of the cage and the inner peripheral surface of the outer ring, and the inner peripheral surface of the cage and the outer peripheral surface of the inner ring, which adversely affects durability.

  Accordingly, an object of the present invention is to improve durability by suppressing heat generation of the fixed type constant velocity universal joint.

The present invention solves the problem by setting the axial offset to 0 and crossing adjacent ball grooves alternately. An axial offset of 0 eliminates the axial offset. In other words, the center O ₁ of the ball groove 16 of the outer ring 10 and the center O ₂ of the ball groove 26 of the inner ring 20 are both the same axis as the angular center O of the joint. It means that it is in the direction position.

  That is, the fixed type constant velocity universal joint of the present invention includes an outer ring 10 in which ball grooves 16 extending in the axial direction are formed on the concave spherical inner peripheral surface 14 at predetermined intervals in the circumferential direction, and a convex spherical outer peripheral surface. 24, an inner ring 20 in which ball grooves 26 extending in the axial direction are formed at predetermined intervals in the circumferential direction, and a ball 30 incorporated between the ball groove 16 of the outer ring 10 and the ball groove 26 of the inner ring 20 that form a pair, A cage 40 interposed between the outer ring 10 and the inner ring 20 and holding the ball 30; the center of the ball groove 16 of the outer ring 10 and the center of the ball groove 26 of the inner ring 20 are the same as the angular center O of the joint. The ball groove 16 of the outer ring 10 and the ball groove 26 of the inner ring 20 which are in the directional position and make a pair intersect each other.

  The axial offset is set to 0 (see FIG. 5A), and the ball groove 16 of the outer ring 10 and the ball groove 26 of the inner ring 20 that intersect with each other are crossed (see FIG. 5B), thereby alternating in the circumferential direction. A wedge angle τ in the opposite direction is generated. Therefore, forces W opposite to each other act on the adjacent balls 30, and the force W applied from the balls 30 to the wall surface 48 of the pocket 46 of the cage 40 is alternately reversed in the circumferential direction, so that the cage position is the outer ring 10 and Stable at the position of the bisector of the inner ring 20. Therefore, the spherical contact between the outer peripheral surface 42 and the inner peripheral surface 44 of the cage 40 is suppressed, the operation of the constant velocity universal joint is smooth even during high loads and high speed rotation, heat generation is suppressed, and durability is improved.

  The number of balls is, for example, 6 (Claim 2), 8 (Claim 3), and 10 (Claim 4). Depending on the number of balls, the ball diameter and the intersection angle of the possible ball grooves change. If the number of balls is small, it is possible to increase the load capacity per ball by increasing the ball diameter and to obtain a large crossing angle, and to increase the wedge angle that affects the operability of the cage. it can. On the other hand, since it is necessary to increase the PCD (pitch circle diameter) of the ball, the outer diameter of the outer ring is increased. When the number of balls is large, the ball diameter is small and the crossing angle is also small. In this case, the wedge angle is reduced, but the cage control force by the wedge angle can be supplemented as much as the number of balls is increased.

  The center of the ball groove of the outer ring and the center of the ball groove of the inner ring may be offset in the radial direction. By adopting such a configuration, it is possible to increase the load capacity of the ball grooves of the outer ring and the inner ring and to increase the thickness of the bottom of the ball groove.

  The ball groove may be formed by forging (Claim 6), or may be formed by machining (Claim 7). By forming the ball groove by forging, post-processing is not necessary, and the cost can be reduced accordingly. Specific examples of machining include grinding and quenching steel cutting that can finish the ball groove with high accuracy. While grinding requires coolant, hardened steel cutting is so-called dry processing that does not use coolant, so the burden on the environment can be reduced.

According to the present invention, heat generation during high load and high speed rotation is suppressed, and durability is improved. Further, since the cage position is stabilized, contact resistance between the cage and the outer ring and between the cage and the inner ring is suppressed, torque loss is reduced, and constant velocity is improved.
More specifically (see FIG. 5), a load W in the opposite direction is generated in the adjacent ball grooves, so that the cage has an axial load of ± 0 as a whole and remains at the position of the bisector. Therefore, the phenomenon that the outer spherical surface of the cage and the inner spherical surface of the outer ring, the inner spherical surface of the cage and the outer spherical surface of the inner ring come into contact with each other, and the contact resistance increases is suppressed. To do. The torque loss in the constant velocity universal joint is caused by power loss due to rolling resistance and slip resistance between the ball groove and the ball, resistance due to contact of the spherical surface portion, and the like. In the constant velocity universal joint according to the present invention, since the contact resistance of the spherical surface portion is suppressed, torque loss is reduced.

Embodiments of the present invention will be described below with reference to the drawings.
First, the basic configuration of the fixed type constant velocity universal joint will be described with reference to FIG. The fixed type constant velocity universal joint mainly includes an outer ring 10 as an outer joint member, an inner ring 20 as an inner joint member, a plurality of balls 30 as torque transmission elements, and a cage 40 for holding the balls 30. As an element.

  As shown in FIG. 2, the outer ring 10 is a disk type and has a through hole 12 for inserting a bolt, and is flange-coupled to the driving shaft or the driven shaft. The inner circumferential surface of the outer ring 10 has a concave spherical shape, and ball grooves 16 are formed at predetermined intervals in the circumferential direction of the inner circumferential surface. The ball groove 16 is inclined with respect to the axis, and the direction of inclination between the adjacent ball grooves 16a and 16b is opposite. The inclination angle is represented by γ.

As shown in FIG. 3, the inner ring 20 has a spline hole 22 formed in the shaft center portion, and is connected to the driven shaft or the driving shaft so that torque can be transmitted through the spline hole 22 (the shaft of FIG. 9). 158). The outer circumferential surface 24 of the inner ring 20 is spherical, and ball grooves 26 are formed at predetermined intervals in the circumferential direction of the outer circumferential surface.
Similar to the ball groove 16 of the outer ring 10, the ball groove 26 of the inner ring 20 is also inclined with respect to the axis, and the direction of inclination of the adjacent ball grooves 26a, 26b is opposite. Again, the inclination angle is represented by the symbol γ.

The ball groove 16 of the outer ring 10 and the ball groove 26 of the inner ring 20 form a pair, and one ball 30 is incorporated between each pair of ball grooves 16 and 26. The number of balls is arbitrary, but specific examples include 6, 8, 10, and the like. The figure shows eight examples.
The ball groove 16 of the outer ring 10 and the ball groove 26 of the inner ring 20 that are paired are assembled so that the directions of inclination are reversed.

  As shown in FIGS. 1 and 4, the cage 40 is interposed between the inner peripheral surface 14 of the outer ring 10 and the outer peripheral surface 24 of the inner ring 20. Therefore, the outer peripheral surface 42 of the cage 40 has a convex spherical shape that matches the inner peripheral surface 14 of the outer ring 10, and the inner peripheral surface 44 of the cage 40 has a concave spherical shape that matches the outer spherical surface 24 of the inner ring 20. Pockets 46 are formed at predetermined intervals in the circumferential direction of the cage 40, and one ball 30 is accommodated in each pocket 46. The pocket 46 penetrates the cage 40 in the radial direction, and the ball 30 accommodated in the pocket 46 faces the ball groove 16 of the outer ring 10 on the outer diameter side of the cage 40, and the ball of the inner ring 20 on the inner diameter side of the cage 40. Facing the groove 26. In this way, all the balls 30 are held on the same plane by the cage 40.

  As shown in FIG. 1B, the axial offset is zero. That is, on the plane including the axis of the joint, the center of the ball groove 16 of the outer ring 10 and the center of the ball groove 26 of the inner ring 20 are both at the same axial position as the angle center O of the joint.

  Here, the axial offset means that the axial position of the center of the ball groove of the outer ring and the center of the ball groove of the inner ring are different. Good.

7 and 8 show an embodiment in which the center of curvature of the ball groove is offset in the radial direction on the plane including the axis of the joint. FIG. 7A shows an example in which the center O ₃ of the ball grooves 16 and 26 is offset in the radial direction in a direction away from the ball grooves 16 and 26 beyond the axis. FIG. 7B shows an example in which the center O ₃ of the ball grooves 16 and 26 is offset in the radial direction from the axis toward the balls 16 and 26. Each symbol F represents an offset amount.

In the embodiment of FIG. 7A, the ball groove 16 of the outer ring 10 can be deepened. 8 (a) is obtained by displayed superimposed the ball grooves of the embodiment of the ball groove of the embodiment of FIG. 7 (a) (bottom) and Figure 7 (b) (bottom), reference numeral R ₁ is of the former indicates the curvature radius of the case, the code R ₂ represents a radius of curvature of the latter. Further, for comparison, an arc having a radius of curvature R ₀ when the center of curvature is on the axis is indicated by a broken line. Symbols t ₀ and t ₁ represent the outer ring wall thickness of the groove bottom portion at the end of the ball groove 16. As can be understood from FIG. 8 (a), the direction away the center of curvature from the ball groove 16, the ball groove 16 of the radius of curvature R ₁ which is radially offset from the axis is deeper than the standard ball grooves indicated by the dashed line Become.

In the embodiment of FIG. 7A, the thickness of the bottom of the ball groove 26 of the inner ring 20 can be increased. FIG. 8 (b), which was displayed superimposed the inner ring of the ball grooves according to embodiments of the Example and the inner ring of the ball groove by the diagram of FIG 7 (a) 7 (b) , reference numeral R ₄ is the case of the former It indicates the curvature radius, reference numeral R ₅ denotes a radius of curvature of the latter. Further, for comparison, there is shown a circular arc of curvature radius R ₃ when the center of curvature is on the axis by a broken line. As can be understood from FIG. 8 (b), in a direction away the center of curvature from the ball groove 26, the inner ring wall thickness t ₃ of the groove bottom portion of the ball grooves 26 of the curvature radius R ₄ that is radially offset from the axis line, It is thicker than inner thickness t ₂ of the groove bottom portion of the standard ball groove indicated by broken lines.

  The axial offset is set to 0 (see FIG. 5A), and the ball groove 16 of the outer ring 10 and the ball groove 26 of the inner ring 20 that intersect with each other are crossed (see FIG. 5B), thereby alternating in the circumferential direction. A wedge angle τ in the opposite direction is generated. Therefore, forces W opposite to each other act on the adjacent balls 30, and the force W applied from the balls 30 to the wall surface 48 of the pocket 46 of the cage 40 is alternately reversed in the circumferential direction, so that the cage position is the outer ring 10 and Stable at the position of the bisector of the inner ring 20. Therefore, the spherical contact between the outer peripheral surface 42 and the inner peripheral surface 44 of the cage 40 is suppressed, the operation of the constant velocity universal joint is smooth even during high loads and high speed rotation, heat generation is suppressed, and durability is improved.

  A constant velocity universal joint is also established when an axial offset is applied and adjacent ball grooves are crossed. However, since the ball always receives a force in one direction, contact between the outer peripheral surface of the cage and the inner peripheral surface of the outer ring and contact between the inner peripheral surface of the cage and the outer peripheral surface of the inner ring cannot be suppressed. Therefore, the problem of heat generation still cannot be solved, and improvement in durability cannot be expected.

  Originally, the axial offset and the crossing angle 2γ are important elements for generating the wedge angle τ and smoothly operating the cage 40, and therefore, it is necessary to set the axial offset and the crossing angle 2γ to a certain extent. Unlike the drive shaft, the propeller shaft does not require a large operating angle, so that the ball groove length of the outer ring 10 and the inner ring 20 can be shortened. Therefore, the intersection angle 2γ can be set large.

  On the other hand, for the drive shaft, since the maximum operating angle is large, it is necessary to set the ball groove lengths of the outer ring and the inner ring long, and the ball groove 26 near the end face of the inner ring 20 as shown by reference numeral 28 in FIG. As a result, the convex spherical outer peripheral surface 24 disappears. Although FIG. 6 shows the case of the inner ring 20, the same applies to the outer ring 10. Further, the amount of movement of the ball 30 in the circumferential direction increases, and it becomes necessary to set the circumferential dimension of the pocket 46 of the cage 40 to be long. Therefore, there is a problem in that the column portion between the pockets 46 becomes thin, leading to a decrease in the strength of the cage 40. Therefore, it may not be practically applied to a front drive shaft that requires a large operating angle, but is applicable to a rear drive shaft that does not take a large operating angle.

(A) is a front view which shows an Example, (b) is AB sectional drawing of Fig.1 (a). (A) is a front view of an outer ring, (b) is a view taken in the direction of arrow Y in FIG. 2 (a), (c) is a sectional view, and (d) is a perspective view. (A) is a front view of an inner ring, (b) is a Z arrow view of FIG. 3 (a), (c) is a sectional view, and (d) is a perspective view. (A) is a front view, (b) is a sectional view, and (c) is a perspective view. (A) is a longitudinal cross-sectional view, (b) is a developed schematic view of a ball groove. It is a perspective view of an inner ring when the axial direction length is long. (A) (b) is a longitudinal cross-sectional view which shows the example of radial direction offset. (A) is a longitudinal sectional view of the outer ring, (b) is a longitudinal sectional view of the inner ring. It is a longitudinal cross-sectional view which shows a prior art example. It is a longitudinal cross-sectional view for demonstrating the influence of an axial direction offset.

Explanation of symbols

10 Outer ring (outer joint member)
12 Through hole 14 Inner peripheral surface 16 Ball groove 20 Inner ring (inner joint member)
22 spline hole 24 outer peripheral surface 26 ball groove 30 ball (torque transmission element)
40 Cage 42 Outer peripheral surface 44 Inner peripheral surface 46 Pocket 48 Wall surface

Claims (7)

An outer ring in which ball grooves extending in the axial direction are formed on the concave spherical inner peripheral surface at predetermined intervals in the circumferential direction;
An inner ring in which ball grooves extending in the axial direction are formed on the convex spherical outer surface at predetermined intervals in the circumferential direction;
A ball assembled between the ball groove of the outer ring and the ball groove of the inner ring,
A cage for holding a ball interposed between the inner peripheral surface of the outer ring and the outer peripheral surface of the inner ring, and the center of the ball groove of the outer ring and the center of the ball groove of the inner ring are the same axial position as the angular center of the joint. And a fixed type constant velocity universal joint in which the ball groove of the outer ring and the ball groove of the inner ring intersect with each other.   The fixed type constant velocity universal joint according to claim 1, wherein the number of balls is six.   The fixed type constant velocity universal joint according to claim 1, wherein the number of balls is eight.   The fixed type constant velocity universal joint according to claim 1, wherein the number of balls is ten.   The fixed type constant velocity universal joint according to any one of claims 1 to 4, wherein the center of the ball groove of the outer ring and the center of the ball groove of the inner ring are offset in the radial direction.   The fixed constant velocity universal joint according to any one of claims 1 to 5, wherein the ball groove is formed by forging.   The fixed constant velocity universal joint according to any one of claims 1 to 5, wherein the ball groove is formed by machining.

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