JP2008002567A - Tripod type constant velocity joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tripod type constant velocity joint having reduced size, weight and cost than conventional one. <P>SOLUTION: A roller 30 eliminates the need for a component equivalent to an inner roller of a conventional roller. A first annular member 32 and a second annular member 33 are mounted on both opening sides of a cylindrical outer roller 31, respectively. The first annular member 32 has a first protruded annular portion 32a protruded toward a roller rotating shaft throughout the periphery on the end face inner periphery side. A ball 34 for rolling relative to the outer roller 31 and a tripod shaft portion 22 is laid between the first annular member 32 and the second annular member 33. Besides, it is arranged for engaging with the first protruded annular portion 32a at the radial inside of the roller rotating shaft. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a tripod type constant velocity joint.

In order to reduce the induced thrust force, for example, Patent Documents 1 to 4 disclose tripod type constant velocity joints having a tripod shaft portion having an elliptical column shape. These tripod shaft portions are formed so as to form a gap with the inner peripheral surface of the roller in the intermediate shaft axial direction and to contact the inner peripheral surface of the roller in the torque transmission direction. Here, the intermediate shaft axial direction means the tripod axial direction, and the torque transmission direction means a direction orthogonal to the intermediate shaft axial direction and the tripod axial direction. Thus, by making the tripod shaft part into an elliptic cylinder, the roller can swing with respect to the tripod shaft part when viewed from the torque transmission direction. Thereby, the roller can roll following the guide groove, and as a result, the induced thrust force is reduced.
Japanese Patent Application Laid-Open No. 2000-257643 JP 2001-295855 A JP 2002-323060 A JP 2005-147369 A

  By the way, especially components mounted on vehicles and the like are always required to be reduced in size, weight, and cost. The same applies to the tripod type constant velocity joint.

  This invention is made | formed in view of such a situation, and it aims at providing the tripod type | mold constant velocity joint which can achieve size reduction, weight reduction, and cost reduction compared with the past.

  The tripod type constant velocity joint of the present invention includes an outer race, a tripod, and a roller. The outer race has a cup shape, and three guide grooves extending in the direction of the rotation axis (hereinafter referred to as “outer race rotation axis”) are formed on the inner peripheral surface. The tripod includes a cylindrical boss portion and three tripod shaft portions that extend from the boss portion to the outside in the radial direction of the intermediate shaft shaft and are inserted into the respective guide grooves. The roller has a cylindrical shape and is rotatably supported by each tripod shaft portion, and is rotatably engaged with the guide groove. The outer peripheral surface of the tripod shaft portion is formed so as to contact the roller in the torque transmission direction in the tripod shaft radial section, and a gap is formed between the tripod shaft portion and the roller in the intermediate shaft axial direction. The tripod shaft portion is formed in, for example, an elliptic cylinder shape.

  And the characteristic matter of this invention is as follows. That is, the roller includes an outer roller, a first annular member, a second annular member, and a ball. The outer roller is a member having a cylindrical shape and engaged with each guide groove so as to be able to roll. The first annular member has an annular shape, and has a first protruding ring portion that protrudes in the roller rotation axis direction over the entire circumference on the inner peripheral side of the end surface, and the first protruding ring portion faces the one opening side of the outer roller. It is a member attached to the other opening side among the inner peripheral sides of an outer roller. The second annular member is an annular member and is a member attached to one opening side of the inner peripheral side of the outer roller. The ball is formed in a spherical shape, is disposed on the inner peripheral side of the outer roller so as to be able to roll on the inner peripheral surface of the outer roller, is disposed so as to be able to roll on the outer peripheral surface of the tripod shaft portion, and the first annular member and the second annular member And is engaged with the first projecting ring portion inward in the radial direction of the roller rotation axis.

  Here, the roller of the conventional tripod type | mold constant velocity joint was provided with the outer roller, the inner roller, the ball | bowl (or needle), and the snap ring (refer patent documents 1-4). In contrast, the tripod type constant velocity joint roller of the present invention does not correspond to a conventional inner roller. Therefore, the outer diameter of the roller of the present invention can be reduced as compared with the prior art. By reducing the outer diameter of the roller, the outer diameter of the tripod constant velocity joint can be reduced. Thus, according to the present invention, the tripod constant velocity joint can be reduced in size. And with size reduction, weight reduction and cost reduction can be achieved.

  As described above, according to the present invention, a size reduction or the like is achieved by eliminating the need for a conventional inner roller. However, in the conventional roller, the inner roller has been used to hold the inner peripheral side of the ball. Therefore, the ball cannot be held simply by removing the inner roller. If the inner roller is simply removed from the conventional roller, for example, the ball may drop off in a gap formed between the elliptical small diameter of the tripod shaft portion and the roller.

  Therefore, in order to solve the falling off of the ball, the first annular member of the present invention has a first projecting ring portion that projects in the roller rotation axis direction over the entire circumference on the inner peripheral side of the end face. Then, the ball engages with the first protruding ring portion on the inner side in the radial direction of the roller rotation axis. Accordingly, the inner side of the ball in the radial direction of the roller rotation axis is always held by the first protrusion. Of course, the outer side of the ball in the radial direction of the roller rotation axis is held by the outer roller. Furthermore, the roller rotation axis direction of the ball is held by the first annular member and the second annular member. Therefore, the ball does not fall off even at a position where a gap is formed between the tripod shaft portion.

  As described above, according to the present invention, the tripod type constant velocity joint can be reduced in size, weight, and cost by eliminating the equivalent of the conventional inner roller without dropping the ball. it can.

  The second annular member has an annular shape having a second protruding ring portion that protrudes in the roller rotation axis direction over the entire inner peripheral side of the end surface, and the second protruding ring portion faces the other opening side of the outer roller. It is good to attach to one opening side among the inner peripheral sides of an outer roller. At this time, the ball is engaged with the second projecting ring portion on the inner side in the radial direction of the roller rotation axis. That is, the inner side of the ball in the radial direction of the roller rotation axis is held by the second protruding ring portion in addition to the first protruding ring portion. Therefore, the ball can be held more reliably.

  Here, the ball engages with the first projecting ring portion on the inner side in the radial direction of the roller rotation axis. Therefore, the cross-sectional shape in the roller rotation axis direction of the engagement surface with the ball in the first protrusion is preferably a curve that follows the outer peripheral surface of the ball. That is, the radially outer shape of the cross section in the roller rotation axis direction of the first protrusion is a curve that follows the outer peripheral surface of the ball. Thereby, contact with a ball and the 1st protruding ring part can be made into multipoint contact or line contact. Therefore, the pressure that the ball receives from the first protruding ring portion can be reduced. As a result, the ball can reliably roll with respect to the first protruding ring portion.

  Further, when the second annular member has the second projecting ring portion, the ball engages with the second projecting ring portion on the inner side in the roller rotation axis radial direction. Therefore, the cross-sectional shape in the roller rotation axis direction of the engagement surface with the ball in the second protrusion is preferably a curve that follows the outer peripheral surface of the ball. That is, the radially outer shape of the cross section in the roller rotation axis direction of the second projecting ring portion is a curve that follows the outer peripheral surface of the ball. Thereby, contact with a ball and the 2nd protruding ring part can be made into multipoint contact or line contact. Therefore, the pressure that the ball receives from the second projecting ring portion can be reduced. As a result, the ball can reliably roll with respect to the second projecting ring portion.

  Here, the ball of the roller of the present invention is in direct contact with the outer peripheral surface of the tripod shaft. Further, the tripod shaft radial section of the tripod shaft portion is, for example, elliptical. Therefore, in a ball that is in contact with the outer roller and the tripod shaft portion, the tangent line between the outer roller and the ball and the tangent line between the tripod shaft portion and the ball may intersect, that is, a wedge state. By the way, when the tripod shaft portion and the outer roller rotate relatively, the ball must roll with respect to the tripod shaft portion and the outer roller. However, if the wedge angle (angle on the side of the tangent line between the tripod shaft portion and the ball and the tangent line between the outer roller and the ball is less than 90 degrees) is large, the ball may be attached to the outer roller or tripod shaft. There is a risk of slipping on the part.

  Therefore, in order for the ball to roll reliably with respect to the outer roller and the tripod shaft, the following conditions may be satisfied. That is, in the tripod type constant velocity joint of the present invention, the friction coefficient between the tripod shaft and the ball is μ1, the friction coefficient between the outer roller and the ball is μ2, the tangent between the tripod shaft and the ball, the outer roller and the ball, When the angle on the side of less than 90 degrees among the angles formed with the tangent line is α, it is preferable to satisfy the following formula 1.

  Thereby, a ball can roll reliably, without sliding with respect to an outer roller and a tripod shaft part.

  According to the tripod type constant velocity joint of the present invention, it is possible to further reduce the size, weight, and cost as compared with the conventional one.

  Next, the present invention will be described in more detail with reference to embodiments. Here, the tripod type constant velocity joint of the present embodiment will be described by taking as an example a case where it is used for coupling a power transmission shaft of a vehicle. Specifically, this is a case where the shaft portion connected to the differential gear and the intermediate shaft are used as a connecting portion.

  The tripod type constant velocity joint will be described with reference to FIGS. FIG. 1 is a sectional view in the axial direction of an intermediate shaft of a tripod type constant velocity joint. FIG. 2 is a view as seen from the upper side of FIG. 1 with the outer race 10 removed from FIG.

  The tripod type constant velocity joint includes an outer race 10 connected to one side shaft (not shown), a tripod 20 connected to the other side shaft (not shown) (intermediate shaft), the outer race 10 and the tripod. 20 and a roller 30 interposed therebetween.

  The outer race 10 is formed in a cup shape (bottomed cylindrical shape), and the outer side of the cup bottom is connected to a shaft on one side. Three guide grooves 11 extending in the outer race rotation axis direction (front-rear direction in FIG. 1) are formed at equal intervals on the inner peripheral surface of the cup-shaped portion of the outer race 10. In FIG. 1, only one guide groove 11 is shown.

  The tripod 20 is disposed inside the cup-shaped portion of the outer race 10. The tripod 20 includes a boss portion 21 and three tripod shaft portions 22. The boss portion 21 has a cylindrical shape, and the inner peripheral side of the boss portion 21 is connected to the end portion of the other side shaft (intermediate shaft).

  Each tripod shaft portion 22 extends outwardly in the radial direction of the intermediate shaft shaft (axial center of the tripod 20) on the outer peripheral side of the boss portion 21 and is equally spaced in the circumferential direction of the boss portion 21. Is formed. The tripod shaft portion 22 has an elliptic cylinder shape. Specifically, as shown in FIGS. 1 and 2, the major axis of the ellipse coincides with the torque transmission direction, and the minor axis of the ellipse coincides with the intermediate shaft axis direction. That is, in the torque transmission direction, the outer peripheral surface of the tripod shaft portion 22 contacts a roller 30 described later. On the other hand, a gap is formed between the outer peripheral surface of the tripod shaft portion 22 and the roller 30 in the intermediate shaft axial direction, so that the outer peripheral surface of the tripod shaft portion 22 does not contact the roller 30.

  The roller 30 has a substantially cylindrical shape as a whole. The roller 30 is pivotally supported on the outer peripheral side of the tripod shaft portion 22 so as to be rotatable around the tripod shaft and slidable in the tripod shaft direction. Further, the roller 30 can swing with respect to the tripod shaft portion 22 when viewed from the torque transmission direction. Further, the roller 30 is disposed in the guide groove 11 so as to be able to roll. The roller 30 includes an outer roller 31, a first annular member 32, a second annular member 33, and a plurality of balls 34.

  The outer roller 31 has a cylindrical shape. The outer peripheral surface of the outer roller 31 has a shape that follows the guide groove 11. Accordingly, the outer roller 31 engages with the guide groove 11 so as to be able to roll about the vertical axis (tripod axis) in FIG. Further, on the inner peripheral surface of the outer roller 31, locking grooves 31a and 31b are formed on the first opening side located on the upper side in FIG. 1 and on the second opening side located on the lower side in FIG.

  The first annular member 32 has an annular shape. On the inner peripheral side of the end surface of the first annular member 32, there is a first protruding ring portion 32a that protrudes in the axial direction (corresponding to the roller rotation axis direction) over the entire circumference. The first annular member 32 is located on the first opening side (upper side in FIG. 1) of the outer roller 31 so that the first protruding ring part 32a faces the second opening side (lower side in FIG. 1) of the outer roller 31. It fits in the locking groove 31a. A radially outer shape of an axial section (corresponding to a roller rotational axis direction section) of the first projecting ring portion 32a has an arc shape having substantially the same diameter as a ball 34 described later. That is, the radially outer shape of the axial section of the first projecting ring portion 32 a is a curve that follows the outer peripheral surface of the ball 34.

  The second annular member 33 is annular. On the inner peripheral side of the end surface of the second annular member 33, there is a second protruding ring portion 33a that protrudes in the axial direction (corresponding to the roller rotation axis direction) over the entire circumference. Then, the second annular member 33 is located on the second opening side (lower side in FIG. 1) of the outer roller 31 so that the second protruding ring portion 33a faces the first opening side (upper side in FIG. 1) of the outer roller 31. It fits into the locking groove 31b. A radially outer shape of an axial section (corresponding to a roller rotational axis direction section) of the second projecting ring portion 33a is an arc having substantially the same diameter as a ball 34 described later. That is, the radially outer shape of the axial section of the second projecting ring portion 33 a is a curve that follows the outer peripheral surface of the ball 34.

  That is, the first annular member 32 and the second annular member 33 are disposed so as to face each other in the roller rotation axis direction. Further, the inner circumferential side separation distance between the first annular member 32 and the second annular member 33 is formed to be narrower than the outer circumferential side separation distance.

  The ball 34 has a spherical shape. The diameter of the ball 34 is set larger than the separation distance on the inner peripheral side between the first annular member 32 and the second annular member 33. The diameter of the ball 34 is equal to or slightly smaller than the separation distance on the outer peripheral side between the first annular member 32 and the second annular member 33.

  And this ball | bowl 34 is arrange | positioned at the inner peripheral side of the outer roller 31 so that it can roll to the inner peripheral surface of the outer roller 31. FIG. Further, the ball 34 is disposed so as to be interposed between the first annular member 32 and the second annular member 33. Accordingly, the ball 34 is engaged with the first projecting ring portion 32 a of the first annular member 32 and the second projecting ring portion 33 a of the second annular member 33 on the inner side in the roller rotation shaft radial direction. That is, the radially outer surfaces of the first projecting ring part 32 a and the second projecting ring part 33 a are the parts that engage with the ball 34. The ball 34 is configured to be able to roll with respect to the radially outer surfaces of the first protruding ring portion 32a and the second protruding ring portion 33a.

  Further, the ball 34 has a size that protrudes to the inner peripheral side from the inner peripheral surfaces of the first annular member 32 and the second annular member 33. That is, the innermost diameter of the roller 30 is an inscribed circle of the plurality of balls 34. The inscribed circle of the plurality of balls 34 is equal to the major axis of the tripod shaft part 22 or slightly larger than the major axis of the tripod shaft part 22. Therefore, the ball 34 can roll with respect to the outer peripheral surface of the tripod shaft portion 22. However, since the tripod shaft portion 22 has an elliptical column shape, as shown in FIG. 2, only the ball 34 positioned near the major axis of the tripod shaft portion 22 is the outer peripheral surface of the tripod shaft portion 22. Roll against.

  Thus, the ball 34 is disposed so as to be sandwiched between the inner peripheral surface of the outer roller 31, the arc-shaped portion of the first protruding ring portion 32a, and the arc-shaped portion of the second protruding ring portion 33a. And the diameter of the ball | bowl 34 is larger than the separation distance of the inner peripheral side of the 1st annular member 32 and the 2nd annular member 33, ie, the separation distance of the 1st protruding ring part 32a and the 2nd protruding ring part 33a. Therefore, the ball 34 does not drop out inside the first annular member 32 and the second annular member 33.

  Next, conditions for the ball 34 to roll reliably with respect to the tripod shaft portion 22 and the outer roller 31 will be discussed with reference to FIGS. 3 and 4. FIG. 3 is a cross-sectional view orthogonal to the tripod axis and passing through the center of the ball 34. However, in FIG. 3, only some of the plurality of balls 34 are shown for ease of explanation. FIG. 4 is a schematic diagram showing the relationship between forces acting on the ball 34.

  Here, as shown in FIG. 3, it is assumed that torque transmission is performed in the direction indicated by the center arrow, and the outer roller 31 rotates with respect to the tripod shaft portion 22 in the direction indicated by the right arrow. Further, consider a case where two adjacent balls 34 are in contact with the vicinity of the major axis of the tripod shaft 22.

  In this case, the ball 34 located on the upper side of FIG. 3 (for convenience, hereinafter, in particular, the ball 34 located on the upper side of FIG. 3 is referred to as “ball 341”) is placed on the tripod shaft portion 22 at point A. Contact and contact the outer roller 31 at point B. Then, the tangent line La between the tripod shaft portion 22 and the ball 341 and the tangent line Lb between the outer roller 31 and the ball 341 are in an intersecting state. That is, it becomes a wedge state. The wedge angle at this time (the angle on the side of less than 90 degrees out of the angles formed by the tangent line La and the tangent line Lb) is α. Further, when torque is transmitted to the right side in FIG. 3 and the outer roller 31 rotates clockwise in FIG. 3, a load P is applied from the tripod shaft portion 22 to the point A of the ball 341.

  Thus, when the load P acts on the ball 341, the ball 341 slides with respect to the tripod shaft 22 and the outer roller 31 in order for the ball 341 to roll with respect to the tripod shaft 22 and the outer roller 31. It is necessary to prevent it from occurring.

  Here, at point A, the component perpendicular to the tangent line La of the load P acting on the ball 341 is Na1, and the component parallel to the tangent line La is Na2. The relationship between the load P, the vertical component Na1, and the parallel component Na2 is shown in Equation 2. Further, the frictional force F1 generated between the ball 341 and the tripod shaft portion 22 is expressed by Equation 3.

  In order to prevent slippage between the ball 341 and the tripod shaft portion 22 at the point A, it is necessary to satisfy Expression 4.

  Substituting Equations 2 and 3 into Equation 4, the relationship of Equation 5 is obtained. That is, by satisfying the relationship of Formula 5, the ball 341 rolls reliably with respect to the tripod shaft portion 22.

  Next, a load Na1 is applied from the ball 341 to the outer roller 31 at point B. At this time, at point B, the component perpendicular to the tangent Lb of the load Na1 acting on the outer roller 31 is Nb1, and the component parallel to the tangent Lb is Nb2. The relationship between the load Na1, the vertical component Nb1, and the parallel component Nb2 is shown in Expression 6. Further, the frictional force F2 generated between the ball 341 and the outer roller 31 is expressed by Equation 6.

  In order to prevent slippage between the ball 341 and the outer roller 31 at the point B, it is necessary to satisfy Expression 8.

  By substituting Equations 6 and 7 into Equation 8, the relationship of Equation 9 is obtained. That is, by satisfying the relationship of Expression 9, the ball 341 rolls reliably with respect to the outer roller 31.

  Here, the wedge angle α varies depending on the relative position between the tripod shaft 22 and the ball 34. For example, when the center of the ball 34 is located on the long axis of the tripod shaft portion 22, the wedge state α is not set, and the wedge angle α is 0 degree. On the other hand, the case where the wedge angle α is maximized is a case where two adjacent balls 34 are in contact with the vicinity of the major axis of the tripod shaft portion 22 as shown in FIG. Specifically, the wedge angle α is maximized when the distance from the major axis of the tripod shaft portion 22 to the center of two adjacent balls 34 shown in FIG. 3 is equal.

  As the wedge angle α increases, tan α increases. Therefore, in order to reliably roll the ball 34 with respect to the tripod shaft portion 22 and the outer roller 31, in the above-described case where the wedge angle α is maximized, the friction coefficients μ1, μ2, and Equations 5 and 9 are satisfied. What is necessary is just to set the outer peripheral surface shape of the tripod shaft part 22.

  As described above, the roller 30 of the present embodiment can be reduced in size, weight, and cost by adopting a configuration that does not require parts corresponding to the inner roller of the conventional roller. Even if a part corresponding to the inner roller is unnecessary, the ball 34 can be held by the first annular member 32 and the second annular member 33.

An intermediate shaft axial direction sectional view of a tripod type constant velocity joint is shown. FIG. 2 is a diagram seen from the upper side of FIG. 1 in a state where the outer race 10 is removed from FIG. 1. It is a figure explaining the conditions for the ball | bowl 34 to roll with respect to the tripod shaft part 22 and the outer roller 31, Comprising: It is a cross section orthogonal to a tripod axis | shaft and passing through the center of the ball | bowl 34. FIG. FIG. 6 is a diagram for explaining conditions for the ball to roll with respect to the tripod shaft portion 22 and the outer roller 31, and is a schematic diagram showing a force relationship acting on the ball.

Explanation of symbols

10: outer race, 11: guide groove,
20: Tripod, 21: Boss part, 22: Tripod shaft part,
30: Roller, 31: Outer roller, 31a, 31b: Locking groove,
32: 1st annular member, 32a: 1st protruding ring part,
33: second annular member, 33a: second projecting ring portion, 34: ball

Claims (6)

An outer race having a cup shape and having three guide grooves formed in the inner peripheral surface extending in the direction of the rotation axis;
A tripod comprising: a cylindrical boss portion; and three tripod shaft portions that extend from the boss portion to the outside in the radial direction of the intermediate shaft shaft and are inserted into the guide grooves.
A roller having a cylindrical shape and rotatably supported by each of the tripod shafts and rotatably engaged with the guide groove;
A tripod type constant velocity joint comprising:
An outer peripheral surface of the tripod shaft portion is formed so as to contact the roller in the torque transmission direction in the tripod shaft radial cross section, and a gap is formed between the roller and the roller in the intermediate shaft axial direction,
The roller is
An outer roller having a cylindrical shape and movably engaged with each of the guide grooves;
The outer roller has a first protruding ring portion that protrudes in the direction of the roller rotation axis over the entire circumference on the inner peripheral side of the end surface, and the first protruding ring portion faces the one opening side of the outer roller. A first annular member attached to the other opening side of the inner peripheral side;
A second annular member comprising an annular shape and attached to one opening side of the inner peripheral side of the outer roller;
It is formed in a spherical shape and is arranged on the inner circumferential side of the outer roller so as to be able to roll on the inner circumferential surface of the outer roller, and is arranged so as to be able to roll on the outer circumferential surface of the tripod shaft portion, and the first annular member and the second annular member A ball that is disposed so as to be interposed between the first member and the inner surface of the first protruding ring portion and engages with the inner side in the radial direction of the roller rotation shaft;
A tripod-type constant velocity joint. The second annular member has an annular shape having a second protruding ring portion that protrudes in the roller rotation axis direction over the entire inner peripheral side of the end surface, and the second protruding ring portion faces the other opening side of the outer roller. Is attached to one opening side of the inner peripheral side of the outer roller,
The tripod type constant velocity joint according to claim 1, wherein the ball is engaged with the second projecting ring portion inwardly in a roller rotation axis radial direction.   2. The tripod constant velocity joint according to claim 1, wherein a cross-sectional shape in a roller rotation axis direction of an engagement surface with the ball in the first projecting ring portion is a curve following the outer peripheral surface of the ball.   The tripod type constant velocity joint according to claim 2, wherein a cross-sectional shape of the engaging surface with the ball in the second projecting ring portion is a curve following the outer peripheral surface of the ball. The friction coefficient between the tripod shaft and the ball is μ1,
The friction coefficient between the outer roller and the ball is μ2,
When the angle on the side of less than 90 degrees among the angles formed by the tangent line between the tripod shaft part and the ball and the tangent line between the outer roller and the ball is α,
The tripod type | mold constant velocity joint as described in any one of Claims 1-4 which satisfy | fills following formula 1.

  The tripod type constant velocity joint according to any one of claims 1 to 5, wherein the tripod shaft portion has an elliptic column shape.

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