JP2007139094A - Constant speed universal joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a constant speed universal joint to be used in a power transmission system for an automobile or various kinds of industrial machines, with an outer ring easy to manufacture. <P>SOLUTION: The constant speed universal joint comprises the outer ring 23 having a plurality of track grooves 22 formed in an inner peripheral face 21 at circumferentially equal spaces along the axial direction, an inner ring having a plurality of track grooves paired with the track grooves 22 of the outer ring 23 and formed in the outer peripheral face at circumferentially equal spaces along the axial direction, a plurality of balls 27 laid between each of the track grooves 22 of the outer ring 23 and each of the track grooves of the inner ring for transmitting torque, and a cage laid between the inner peripheral face 21 of the outer ring 23 and the outer peripheral face of the inner ring for holding the balls 27. The cross section of the track groove 22 of the outer ring 23 consists of a gothic arch portion 22a having angular contact with the balls 27, and a run off portion 22b formed in a range from a site beyond a contact point Y of the gothic arch portion 22a with the balls 27 to a shoulder portion X of the track groove 22 and set back from the curvature radius face of the gothic arch portion 22a. The track groove 22 and the run off portion 22b of the outer ring 23 are finished with forging. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a constant velocity universal joint, for example, a constant velocity universal joint used in a power transmission system of an automobile or various industrial machines.

  For example, there is a fixed type constant velocity universal joint as a kind of constant velocity universal joint used as means for transmitting rotational force from an engine of an automobile to wheels at a constant speed. This fixed type constant velocity universal joint has a structure in which two shafts on the driving side and the driven side are connected and the rotational torque can be transmitted at a constant speed even if the two shafts have an operating angle. In general, as the above-mentioned fixed type constant velocity universal joint, a Barfield type (BJ) and an undercut free type (UJ) are widely known.

  For example, the BJ type fixed type constant velocity universal joint has an outer ring as an outer member in which a plurality of track grooves are formed along the axial direction at equal intervals in the circumferential direction on the spherical inner circumferential surface, and the spherical outer circumferential surface. A plurality of track grooves paired with the track grooves of the outer ring are formed along the axial direction at equal intervals in the circumferential direction, and interposed between the inner ring as the inner member and the track groove of the outer ring and the track groove of the inner ring Thus, a plurality of balls for transmitting torque and a cage for holding the balls interposed between the inner peripheral surface of the outer ring and the outer peripheral surface of the inner ring are provided. The plurality of balls are accommodated in pockets formed in the cage and arranged at equal intervals in the circumferential direction.

  The outer ring is generally manufactured in the following manner. First, a cylindrical billet is formed into a schematic shape of an outer ring by cold forging, and the outer peripheral surface, inner peripheral surface and end surface of the outer ring material are turned. Then, heat treatment is performed, and the outer ring is manufactured by finishing the inner peripheral surface and the track groove by polishing or quenching steel cutting.

  The track groove of the outer ring has a single circular arc surface shape having a predetermined center of curvature in the longitudinal section along the axial direction, and the cross-sectional shape thereof is a curved surface shape in which the track groove and the ball are in angular contact. . Further, an escape portion that recedes from the radius of curvature of the track groove is formed between the portion of the track groove beyond the ball contact point and the shoulder of the track groove (see, for example, Patent Document 1).

  Since the clearance portion is formed in this manner, the clearance between the shoulder portion of the track groove and the ball can be increased. Therefore, when the ball rolls in the track groove, the shoulder portion of the track groove is deformed or burrs due to scratches. Can be prevented from deforming due to scratches and burrs from interfering with the ball, and the contact ellipse between the ball and the track groove when torque is applied is reduced. It is possible to stabilize the bending torque by restraining the ball from riding on the shoulder of the ball.

When this type of constant velocity universal joint is used, for example, in an automobile drive shaft, the outer ring is connected to the driven shaft, and the drive shaft extending from the sliding type constant velocity universal joint attached to the inner ring on the differential on the vehicle body is splined. The structure is connected by fitting. In this constant velocity universal joint, when an operating angle is given between the outer ring and the inner ring, the ball accommodated in the cage is always maintained in the bisector of the operating angle at any operating angle. Is constant speed.
JP 2002-310180 A

  By the way, the outer ring, which is a component of the conventional constant velocity universal joint described above, is manufactured by cold forging, turning, and heat treatment, and finally finishing the track groove such as grinding. In this way, if track groove finishing is performed after cold forging, turning and heat treatment, the cost of equipment and tools for finishing track grooves is increased, and the finishing process takes time. In addition, the material yield was inconvenient.

  The present invention has been proposed in view of the above-mentioned problems, and an object of the present invention is to provide a constant velocity universal joint that can facilitate the production of an outer ring.

  In the present invention, by finishing the track groove and the relief portion of the outer member by forging, finishing processing such as grinding is unnecessary for the track groove of the outer member, No tool is required, the processing time can be shortened, the outer member can be efficiently manufactured, and the cost of the product can be reduced.

  Here, the “part beyond the contact point” is a boundary part between the Gothic arch part and the relief part, and is located between the Gothic arch part, the contact point of the ball and the shoulder of the track groove, and the position is a scratch. And the size of the burr and the size of the contact ellipse between the ball and the track groove when a torque is applied. In addition, “retreat from the curvature radius surface of the Gothic arch portion” means that if the track groove surface at the relief portion virtually forms a groove surface by the curvature radius of the Gothic arch portion, the virtual groove surface This means that the gap with the ball is larger than the case.

  Moreover, it is desirable that the relief portion in the present invention is continuously connected to the curvature radius surface of the Gothic arch portion at a portion beyond the contact point and has a shape formed at the time of forging. Here, “continuously connected” means that both groove surfaces are smoothly connected at the boundary between the Gothic arch portion and the relief portion.

  If the relief portion is formed in this way, the clearance between the track groove shoulder and the ball can be increased, so that when the ball rolls in the track groove, the track groove shoulder is not deformed or burred by scratches. Even if they exist, deformation and burrs due to the scratches can be prevented from interfering with the ball, and the contact ellipse between the ball and the track groove when torque is loaded is reduced. It is possible to stabilize the bending torque by preventing the ball from riding on the shoulder.

  The present invention also relates to a barfield type fixed constant velocity universal joint (BJ) having an outer member and an inner member having track grooves each having a single circular arc surface in the longitudinal direction in the axial direction, The present invention is applicable to both an outer member having a track groove having a straight bottom parallel to the direction and an undercut free type fixed constant velocity universal joint (UJ) having an inner member. The present invention is also applicable to other fixed type constant velocity universal joints having track groove shapes other than these bar field type and undercut free type. Furthermore, the present invention can also be applied to a double offset type sliding constant velocity universal joint (DOJ) and a cross groove type sliding constant velocity universal joint (LJ).

  According to the present invention, by finishing the track groove and the relief portion of the outer member by forging, a finishing process such as grinding is unnecessary for the track groove of the outer member, which is necessary for the finishing process. Equipment and tools are not required, the processing time can be shortened, the outer member can be efficiently manufactured, and the cost of the product can be reduced.

  Further, if the relief shape is set so that a predetermined relief shape can be obtained by using a spring back at the time of forging, an excessive forging load is not required, so that the life of the forging die can be extended.

  An embodiment of a constant velocity universal joint according to the present invention will be described in detail. In the following embodiment, a Barfield type fixed constant velocity universal joint (BJ) is illustrated.

  As shown in FIG. 2, the constant velocity universal joint includes an outer ring 23 as an outer member in which a plurality of track grooves 22 are formed along the axial direction at equal intervals in the circumferential direction on a spherical inner peripheral surface 21, and a spherical surface. A plurality of track grooves 25 that are paired with the track grooves 22 of the outer ring 23 on the outer peripheral surface 24 are formed along the axial direction at equal intervals in the circumferential direction, and the track grooves 22 of the outer ring 23. Between the inner ring 26 and the track groove 25 of the inner ring 26 to transmit torque, and between the spherical inner peripheral surface 21 of the outer ring 23 and the spherical outer peripheral surface 24 of the inner ring 26. 27 and a cage 28 for holding 27. The plurality of balls 27 are accommodated in pockets 29 formed in the cage 28 and arranged at equal intervals in the circumferential direction.

  When this type of constant velocity universal joint is used for a drive shaft of an automobile, for example, an outer ring 23 is connected to a driven shaft, and a drive shaft extending from a sliding type constant velocity universal joint attached to the inner ring 26 on a differential on the vehicle body side. Are connected by spline fitting. In this constant velocity universal joint, when an operating angle is given between the outer ring 23 and the inner ring 26 as shown in FIG. 3, the ball 27 accommodated in the cage 28 always has an operating angle of any operating angle. It is maintained in the bisection plane and the constant velocity of the joint is ensured.

The outer ring 23 constituting a part of the constant velocity universal joint of this embodiment has a track groove having a single circular arc surface shape with a longitudinal section along the axial direction having a predetermined center of curvature on the spherical inner peripheral surface 21. 22 is formed. FIG. 1 is a transverse sectional view showing a track groove 22 formed on the spherical inner peripheral surface 21 of the outer ring 23. As shown in the figure, the cross-sectional shape of the track groove 22 is formed in a Gothic arch shape up to a portion Z beyond the contact point Y that makes angular contact with the ball 27, and the track groove 22 extends from the portion Z beyond the ball contact point Y. of until shoulder X, constructed by than the radius of curvature R ₁ of the Gothic arch portion 22a continuously formed in a curved shape with a large radius of curvature R _2.

The Gothic arch portion 22a have a track groove center O ₁ of the ball 27 of the radius r is located on a line obtained by extending the line connecting the contact point Y and the ball center O of the track grooves 22 and the angular contact to the ball center side And a radius of curvature R ₁ larger than the ball radius r. With the Gothic arch shape as described above, the contact between the track groove 22 and the ball 27 is an angular contact having a ball contact angle α. The formation angle β of the gothic arch portion 22a is larger than the ball contact angle α and extends to the portion Z exceeding the contact point Y.

From the site Z above this contact point Y until the shoulder X of the track groove 16 is provided with a relief portion 22b which is formed in a curved shape with a large radius of curvature R ₂ than the radius of curvature R ₁ of the Gothic arch portion 22a . The escape portion 22b is provided so as to retract from the curvature radius surface of the Gothic arch portion 22a, on a line extended ball contact point Y and the ball center O, and a line segment connecting the track groove center O ₁ to the track groove center side Is formed by the relief center O ₂ located at Here, the ball contact angle α means an angle formed by the ball contact point Y where the ball 27 and the track groove 22 are in contact with the center O of the ball 27 and the groove bottom center Q of the track groove 22.

This escape portion 22b, by forming a large radius of curvature R ₂ than the radius of curvature R ₁ of the Gothic arch portion 22a, since the gap between the shoulder portion X and the ball 27 of the track groove 22 is increased, the track grooves 22 When the ball 27 rolls at this point, even if deformation or burrs due to scratches exist on the shoulder portion X of the track groove 22, it is possible to suppress the deformation or burrs due to the scratches from interfering with the balls 27. In addition, the contact ellipse M between the ball 27 and the track groove 22 when torque is applied can be reduced, and the ball 27 can be prevented from riding on the shoulder X, so that the bending torque can be stabilized. .

Meanwhile, although the contact ellipse M during torque load decreases, the contact surface pressure is increased, to influence the durability, the radius of curvature R ₂ of the relief portion 22b is set to an optimum value depending on the operating conditions There is a need to. The contact ellipse M has a ball contact center P, and has an asymmetric shape from the ball contact center P between the track groove bottom side and the track groove open side.

  The boundary portion between the Gothic arch portion 22a and the relief portion 22b is connected smoothly with the continuity between the Gothic arch portion 22a and the relief portion 22b being maintained. It is set to be larger than the angle α and smaller than the angle γ to the shoulder portion X of the track groove 22. The formation angle β of the Gothic arch portion 22a is determined by the assumed deformation or burr size due to a flaw and the size of the contact ellipse M between the ball 27 and the track groove 22 when torque is applied.

  As described above, the compound gothic arch-shaped track groove 22 composed of the gothic arch portion 22a and the relief portion 22b replaces the curved relief portion 22b with the track groove 16 from the portion Z beyond the ball contact point Y. A straight relief portion extending in a tangential direction at a portion Z exceeding the ball contact point Y between the shoulder portion X and the shoulder portion X can be used.

  The track groove and the relief portion are finished by forging. That is, when the track groove 16 is formed by cold forging, it is easy to form a composite Gothic arch shape composed of the Gothic arch portion 22a and the relief portion 22b by previously forming the die shape into a composite Gothic arch shape. .

  In the forging of the outer ring 23 described above, the punch is pressed against the inner surface of the outer ring material to form the track groove 22, and the material is plastically flowed to the inner peripheral surface side to be formed into the shape of the outer ring 23. For this reason, it becomes difficult to fill the material on the inner peripheral surface side particularly in a portion where the track groove 22 is deep. On the other hand, the escape amount may be set larger in the deep part of the track groove 22 than in the shallow part. The escape portion 22b may be formed by providing a portion corresponding to the escape portion 22b on the above-described punch and transferring it, or the escape portion 22b may be formed by using a spring back or the like during forging. Alternatively, the predetermined relief portion 22b may be formed by controlling the shape thereof. Thereby, a predetermined relief shape can be obtained without forging with an excessive forging load.

  Since the track groove 22 and the relief portion 22b of the outer ring 23 are finished by forging as described above, the track groove 22 of the outer ring 23 does not require finishing such as grinding. A tool is not required, the processing time can be shortened, the outer ring 23 can be efficiently manufactured, and the cost of the product can be reduced.

In the case relief unit is not limited to straight or curved described above, the track groove surfaces in the relief portion has a groove surface by the radius of curvature R ₁ of the Gothic arch portion 22a virtually, What is necessary is just to form so that the clearance gap with the ball | bowl 27 may become large rather than the case of the virtual groove surface. Although the track groove 22 of the outer ring 23 has been described, it is needless to say that the shape of the track groove 25 of the inner ring 26 may be a composite Gothic arch shape composed of the Gothic arch portion 22a and the relief portion 22b described above.

  In the above-described embodiment, the present invention is applied to a barfield-type fixed constant velocity universal joint including an outer ring 23 and an inner ring 26 having track grooves 22 and 25 having a single circular arc surface in the longitudinal direction in the axial direction. Although the case has been described, the present invention is not limited to this, and as shown in FIG. 4, an outer ring 23 ′ and an inner ring 26 ′ having track grooves 22 ′ and 25 ′ having straight bottoms parallel to the axial direction are provided. The present invention can also be applied to an undercut free fixed constant velocity universal joint. Furthermore, the present invention can also be applied to other fixed type constant velocity universal joints having track groove shapes other than these bar field type and undercut free type. Furthermore, the present invention can also be applied to a double offset type sliding constant velocity universal joint (DOJ) and a cross groove type sliding constant velocity universal joint (LJ).

It is sectional drawing which shows the contact state of the track groove and ball | bowl of an outer ring | wheel in embodiment of the constant velocity universal joint which concerns on this invention. 1 is a cross-sectional view showing an overall configuration of a barfield type fixed constant velocity universal joint in an embodiment of the present invention. FIG. 3 is a cross-sectional view showing a state in which an outer ring and an inner ring of the constant velocity universal joint of FIG. 2 take an operating angle. It is sectional drawing which shows the whole structure of the undercut free type constant velocity universal joint in other embodiment of this invention.

Explanation of symbols

21 Spherical inner peripheral surface 22 Track groove 22a Gothic arch portion 22b Escape portion 23 Outer member (outer ring)
24 Spherical outer peripheral surface 25 Track groove 26 Inner member (inner ring)
27 balls 28 cage

Claims (2)

  An outer member in which a plurality of track grooves are formed along the axial direction in the circumferential direction on the inner peripheral surface, and a plurality of track grooves that are paired with the track grooves of the outer member on the outer peripheral surface are equally spaced in the circumferential direction. An inner member formed along the axial direction, a plurality of balls interposed between the track groove of the outer member and the track groove of the inner member, and transmitting torque, and the inner member of the outer member A cage for holding the ball interposed between the peripheral surface and the outer peripheral surface of the inner member, and the cross-sectional shape of the track groove of the outer member is a Gothic arch portion that is in angular contact with the ball; In the constant velocity universal joint formed between the Gothic arch portion and the portion exceeding the contact point of the ball and the shoulder portion of the track groove, and configured as a relief portion retreating from the radius of curvature of the Gothic arch portion, The track groove and relief Constant velocity universal joint, characterized in that finished with concrete.   2. The constant velocity according to claim 1, wherein the relief portion has a shape that is continuously connected to a curvature radius surface of the Gothic arch portion at a portion beyond the contact point, and is shaped to be controlled to be a predetermined shape during forging. Universal joint.

Images