JP2006009863A - Tripod type constant velocity universal joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the lifespan of a joint from being decreased by the advancement of wear due to the contact of the same part of the outer diameter route surface of a ring with balls since the ring of a roller assembly fitted onto the leg shaft of a tripod member is less liable to be rotated relative to the leg shaft. <P>SOLUTION: This tripod type constant velocity universal joint is formed so that the outer diameter cross section of the leg shaft 22 is brought into contact with the inner peripheral surface of the ring 32 at two points or more when the torque is applied thereto. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a tripod type constant velocity universal joint.
In general, a constant velocity universal joint is a kind of universal joint that connects two shafts on the driving side and the driven side and can transmit a rotational force at a constant speed even if there is an angle between the two shafts. The constant velocity universal joint includes a fixed type and a sliding type, and the sliding type allows relative axial displacement between two axes by plunging the joint. One type of sliding type is a tripod type, which connects a tripod member having three leg shafts protruding in the radial direction to one shaft. Further, a hollow cylindrical outer joint member having three track grooves extending in the axial direction is coupled to the other shaft. Then, the torque is transmitted by engaging the leg shaft of the tripod member in the track groove of the outer joint member.

  Non-Patent Document 1 shows the most basic tripod type constant velocity universal joint. The tripod type constant velocity universal joint includes an outer joint member and a tripod member, and one of the two shafts to be coupled is connected to the outer joint member and the other is connected to the tripod member. The outer joint member has a bottomed cylindrical shape and has three track grooves extending in the axial direction on the inner periphery. Cylindrical roller guide surfaces are formed on the side walls facing each other in the circumferential direction of each track groove. The tripod member has three leg shafts protruding in the radial direction, and a needle roller and a ring are carried on each leg shaft. This ring is received in the track groove of the outer joint member.

The outer peripheral surface of the leg shaft is an elliptical shape or a circle whose major axis is orthogonal to the axis of the joint so that the ring can slide along the leg shaft, and is a straight shape parallel to the axis of the leg shaft in the longitudinal section. . The ring externally fitted on the leg shaft has a cylindrical inner peripheral surface, and the outer periphery is a part of a spherical surface, that is, a partial spherical surface. A plurality of needle rollers are incorporated between the ring and the leg shaft.
Further, the tripod type constant velocity universal joint includes a type as shown in FIG. That is, it consists of an outer joint member and a tripod member, and one of the two shafts to be connected is connected to the outer joint member, and the other is connected to the tripod member. The outer joint member 10 has a bottomed cylindrical shape and has three track grooves 12 extending in the axial direction on the inner periphery. Cylindrical roller guide surfaces 14 are formed on the side walls of each track groove 12 facing each other in the circumferential direction. The tripod member 20 has three leg shafts 22 projecting in the radial direction, and a roller assembly (32, 34, 36) is carried on each leg shaft 22. This roller assembly is received in the track groove 12 of the outer joint member 10.

The outer peripheral surface of the leg shaft 22 has an elliptical shape in which the long axis is perpendicular to the joint axis so that the leg shaft 22 can swing with respect to the roller assembly (32, 34, 36) in the direction perpendicular to the plane of FIG. Yes, in the longitudinal section, it is a straight shape parallel to the axis of the leg shaft.
The roller assembly includes a ring 32, a roller 34 and a ball 36. The ring 32 externally fitted to the leg shaft 22 has an annular shape in which the longitudinal section of the inner peripheral surface is a convex arc shape, and includes two inner track surfaces 33a and 33b on the outer periphery. Here, the roller 34 has a two-part structure and is composed of a pair of roller portions 34a and 34b that are in contact with each other at a plane perpendicular to the axis. The outer peripheral surface of each roller part 34a, 34b is a part of a spherical surface having a center of curvature, that is, a partial spherical surface, at a point located in a radial direction away from the axis. Each of the roller portions 34a and 34b includes two outer raceway surfaces 35a and 35b on the inner periphery. The ring 32 and the roller 34 are unitized via a plurality of balls 36 to constitute a roller assembly that can rotate relative to each other. That is, the double-row balls 36a and 36b are movably interposed between the inner raceway surfaces 33a and 33b on the outer periphery of the ring 32 and the outer raceway surfaces 35a and 35b on the inner periphery of the roller 34. The balls 36 are assembled in a so-called full ball state in which as many balls as possible are placed and there is no cage.

  The roller guide surface 14 of the outer joint member 10 that contacts the outer peripheral surface of the roller 34 has a cross-sectional shape that matches the outer peripheral surface of the roller 34. Here, the cross-sectional shape of the roller guide surface 14 is a Gothic arch shape, whereby the roller 34 and the roller guide surface 14 form an angular contact. Although not shown, even if the roller guide surface 14 has a tapered cross section with respect to the outer peripheral surface of the spherical roller, the angular contact between them can be realized. By adopting such a configuration in which the roller 34 and the roller guide surface 14 form an angular contact, the posture of the roller 34 is stabilized because the roller 34 is less likely to shake. When the angular contact is not employed, for example, the roller guide surface 14 is constituted by a part of a cylindrical surface whose axis is parallel to the axis of the outer joint member 10, and the cross-sectional shape thereof is a generatrix of the outer peripheral surface of the roller 34. It can also be an arc corresponding to.

  As a conventional sliding tripod type constant velocity universal joint, there is a type using a full-roller type needle roller in addition to a rolling element using a ball as shown in the illustrated example. In the needle roller, an eccentric load such as an edge load is likely to act on the rolling element surface due to a skew of the rotating roller or the like. Furthermore, the contact state is not stable due to the internal clearance and accuracy, and the edge load acts even if the spherical roller is tilted. In addition, relative slippage also occurs between the end of the spherical roller and the leg shaft and the retaining ring for preventing the needle rollers from being structurally structured.

In the roller assembly of Non-Patent Document 1, a needle bearing or a sliding bearing is used to support the roller.
JP 2000-227124 A JP 2001-295855 A JP 2000-257463 A JP2000-346088 JP 2002-323060 A Universal Joint and Driveshaft Design Manual Section 3.2.6 “Tripot Universal Joint (End Motion Type)”

  The outer diameter of the three leg shafts of the tripod member has a cylindrical shape, and a ring serving as an inner ring of a ball bearing of the roller assembly is fitted on the leg shaft so that the roller can rotate only around the leg shaft. The friction generated by the contact between the leg shaft and the inner diameter of the ring is very large compared to the friction of the ball bearing raceway surface. Due to this friction, the ring cannot rotate freely around the leg axis. Therefore, due to the torque action of the constant velocity universal joint, the force from the rolling element always acts on the raceway surface of the ring, and especially under the condition where the torque is large, the wear of the raceway surface of the ring is promoted and the service life is shortened. descend. In particular, in the case of the leg shaft cross-section as shown in FIGS. 8, 9, and 10, it has been experimentally found that the raceway surface of the outer surface of the ring is severely worn and the life is shortened.

  The present invention is characterized in that the number of contact points between the leg shaft and the inner diameter portion of the ring that are in contact with each other during torque transmission is increased from one point to a plurality of points. The fitting between the leg shaft and the ring is a clearance fit so that the ring can rotate around the leg shaft. The plurality of contact points are made of four or more convex arcs or convex curves in the contour of the leg axis. These convex arcs or convex curves abut on the inner diameter of the ring to form contact points. The specific shape of the outer diameter of the leg shaft is, for example, a shape in which four or five circles are partially overlapped one by one in the circumferential direction, or two ellipses are completely separated with their long axes parallel to each other Or have a partially overlapped shape.

  When a ring constituting the inner ring of the roller assembly is fitted onto the leg shaft having such a cross-sectional shape, a plurality of (at least two) leg shafts with respect to the inner diameter of the ring when the driving force of the constant velocity universal joint is transmitted. By the resultant force of the frictional force acting on the contact point, a moment acts in the rotation direction of the ring, and the relative rotation between the leg shaft and the ring is promoted.

  In the present invention, as described above, the outer diameter contour of the leg shaft is asymmetric with respect to the outer diameter center line perpendicular to the joint axis, and the outer diameter cross section of the leg shaft and the inner peripheral surface of the ring are two or more points. When a rotational torque acts on the joint, the rotational moment is generated by the resultant force (vector sum) of the frictional forces acting on these contact points. This rotational moment causes the ring to rotate relative to the leg shaft, alleviating the problem of wear on the outer diameter raceway surface of the ring, and improving the life of the constant velocity universal joint.

FIG. 1 is a cross section of a tripod constant velocity universal joint according to the present invention using a single row deep groove ball bearing in a roller assembly. The present invention uses not only such a single row deep groove ball bearing but also an angular contact single row ball bearing, a double row deep groove ball bearing, a DB (back-to-back) type double row angular ball bearing, and a needle bearing. It may be a thing.
The outer diameter contour of the leg shaft 22 of the constant velocity universal joint is a shape that abuts on the cylindrical inner diameter surface of the ring 32 fitted on the leg shaft 22 at four or more points in the drawing. 2 to 4 show three typical embodiments of the outer diameter contour of the leg shaft 22. 2 to 4 show a state in which the outer diameter of the leg shaft 22 is in contact with the inner diameter of the ring 32 at four or five points. However, since the outer diameter of the leg shaft 22 is actually fitted to the inner diameter of the ring 32, FIG. Therefore, when the rotational torque is applied, the outer diameter of the leg shaft 22 is in contact with the inner diameter of the ring 32 at two or three points in FIGS. In FIG. 2, four (even number) arcs R ₁ , R ₂ , R ₃ , R ₄ are formed on the outer diameter of the leg shaft 22. The radius of the four arcs is equal to R ₁ and R _{3 and} equal to R ₂ and R ₄ . _One center of each arc R ₁ , R ₂ , R ₃ , R ₄ exists in each quadrant when the central axis is the X axis and the Y axis.

  As shown in FIG. 2, the outer diameter contour of the leg shaft 22 is vertically symmetric with respect to a center line (X axis in FIG. 2) orthogonal to the axis of the tripod constant velocity universal joint. On the other hand, the outer diameter contour of the leg shaft 22 with respect to the center line (Y axis) parallel to the axis of the tripod type constant velocity universal joint is left-right asymmetric.

That is, when considering the constant velocity universal joint from the viewpoint of function, a plane formed by the outer joint member 10 (the trunnion shaft) and the drive shaft connected to the tripod (a horizontal path passing through the center of the leg shaft 22 in FIGS. 2 to 4). It is desirable that the center line, that is, the X axis) is vertically symmetric because of the torque transmission (drive / driven) relationship. In the case of the vertically symmetrical shape, θ ₁ = θ ₃ , θ ₂ = θ ₄ , R ₁ = R ₃ , R ₂ = R ₄ in FIG. However, the outer joint member 10 (the trunnion shaft) is included and is symmetrical with respect to the plane direction perpendicular to the drive shaft connected to the tripod (the vertical center line passing through the center of the leg shaft 22 in FIGS. 2 to 4). Need not be.

In FIG. 3, five (odd number) arcs R ₁ , R ₂ , R ₃ , R ₄ , R ₅ are formed on the outer diameter of the leg shaft 22. The center of each arc R ₁ , R ₂ , R ₃ , R ₄ exists in each quadrant. The center of the arc R ₅ is on the X axis. Even with such an odd number of arcs arranged, the torque transmission action is exactly the same as in FIG. 2 in which one arc R ₅ is omitted from FIG. This is because the arc R ₅ has a tangent parallel to the torque transmission direction, and no torque acts on the contact portion of the arc R ₅ . The symmetrical shape with respect to X of the outer diameter contour of the leg shaft 22 and the asymmetric shape with respect to the Y axis are the same as in the case of FIG.

In FIG. 4, four corners are formed on the outer diameter of the leg shaft 22. The four corners are neither acute nor obtuse, but are composed of convex curves in the vicinity of the major axis end of the ellipse, some of which are indicated by broken lines. Each corner exists separately in each quadrant. The minor axis of the ellipse having the major axis a ₁ is indicated by “b ₁ ”. The minor axis of the ellipse having the major axis a ₂ is indicated by “b ₂ ”. The symmetrical shape with respect to X of the outer diameter contour of the leg shaft 22 and the asymmetric shape with respect to the Y axis are the same as in the case of FIG.

  Note that the cross-sectional shape of the leg shaft 22 can be a straight line 37 at a portion not involved in contact with the ring 32 as shown in FIG. This is because a curved line has a complicated machining process, so that the machining cost is reduced by linearization. It should be noted that a portion not related to contact has a function as a reservoir for the lubricant, and therefore it is desirable to ensure a sufficient clearance with the ring 32.

  Although the three embodiments of the outer diameter contour of the leg shaft have been described above, the important point of the present invention is that the friction is handled from the dynamic viewpoint. When the constant velocity joint rotates while transmitting torque, the leg shaft 22 and the ring 32 are in line contact at two locations. When this fit is a clearance fit, the contact portion moves, and a frictional force acts on the contact portion by this movement. The contact force of the two line contacts varies depending on the transmission torque and the angle (operating angle) of the constant velocity universal joint. Due to this variation, the frictional force at each contact point also varies. Relative rotation occurs between the leg shaft 22 and the ring 32 due to the rotational moment generated by the resultant force of these varying frictional forces.

  The above-mentioned rotational moment is generated even in the shape of the leg shaft 22 as shown in FIGS. 8, 9 and 10, but this shape is a line contact at one point, the magnitude of the moment is very small, and the ring is positive. It is thought that it does not reach to rotate it. Even in the actual experiment, it was confirmed that the movement of the ball contact portion with respect to the outer diameter raceway surface of the ring could not be confirmed, and therefore the bearing raceway surface was worn. On the other hand, in an experiment performed with the contact portion increased to two as shown in FIG. 2, the relative rotation between the leg shaft 22 and the ring 32 was confirmed, and no wear on the bearing raceway surface was observed. The above phenomenon has also been confirmed by analysis, and it has been confirmed that when the contact portion between the leg shaft 22 and the ring 32 is increased to a plurality, the relative rotation between the leg shaft 22 and the ring 32 is promoted.

  The present invention is characterized by the number of contact points between the leg shaft 22 of the tripod member of the tripod type constant velocity joint to which the deep groove ball bearing is applied and the inner diameter of the ring 32, but the roller guide surface 14 of the outer joint member 10 and the outer circumference of the roller The contact shape with the surface can be applied to the shape shown in FIGS. 6 (A) to 6 (D). 6A shows a circular contact between the outer peripheral surface of the partially spherical roller 34 and the roller guide surface 14 of the outer joint member, and FIG. 6B shows the outer peripheral surface of the partial spherical roller 34 and the outer joint. (C) is an angular contact between the roller guide surface 14 of the member 10 and (C) is a circular contact between the outer peripheral surface of the partially spherical roller 34 and the roller guide surface 14 of the outer joint member 10. The outer peripheral surface of the partially spherical roller 34 and the roller guide surface 14 of the outer joint member 10 are in angular contact.

Sectional drawing of the tripod type constant velocity universal joint which used the deep groove ball bearing for the roller assembly. Sectional drawing of the roller assembly of the tripod type | mold constant velocity universal joint which concerns on 1st Embodiment of this invention. Sectional drawing of the roller assembly of the tripod type | mold constant velocity universal joint which concerns on 2nd Embodiment of this invention. Sectional drawing of the roller assembly of the tripod type | mold constant velocity universal joint which concerns on 3rd Embodiment of this invention. Sectional drawing which shows the modification of the outer diameter outline of a leg axis. It is sectional drawing which shows the contact part of a roller and a roller guide surface, Comprising: (A) is a fragmentary sectional view which made the circular contact of the outer peripheral surface of a partially spherical roller, and the roller guide surface of an outer joint member, (B ) Is a partial sectional view in which the outer peripheral surface of the partially spherical roller and the roller guide surface of the outer joint member are in angular contact, and (C) is the outer peripheral surface of the partial spherical roller and the roller guide surface of the outer joint member. FIG. 4D is a partial cross-sectional view in which circular contact is made, and FIG. 4D is a partial cross-sectional view in which an outer peripheral surface of a partially spherical roller and a roller guide surface of an outer joint member are in angular contact. Sectional drawing of the conventional tripod type constant velocity universal joint. Sectional drawing of the roller assembly which has a leg axis | shaft which made one circle the outer diameter outline. Sectional drawing of the roller assembly which has a leg axis | shaft which made the external shape outline the shape which superposed | stacked two circles. Sectional drawing of the roller assembly which has a leg axis | shaft which made the outer diameter outline of one ellipse.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Outer joint member 12 Track groove 14 Roller guide surface 20 Tripod member 22 Leg shaft 32 Ring 34 Roller 36 Ball

Claims (6)

An outer joint member having three track grooves each having a cylindrical roller guide surface arranged in a circumferential direction, a tripod member having three leg shafts projecting in the radial direction, and the track grooves A tripod type that includes an inserted roller and a ring that is externally fitted to the leg shaft and rotatably supports the roller, and the roller is movable in the axial direction of the outer joint member along the roller guide surface. In the universal joint, the outer diameter contour of the leg shaft is asymmetric with respect to the outer diameter center line perpendicular to the axis of the joint, and the outer diameter cross section of the leg shaft and the inner peripheral surface of the ring are two points at the time of torque load. A tripod type constant velocity universal joint characterized by the above contact. The tripod type constant velocity universal joint according to claim 1, wherein a curve including each contact point of the outer diameter cross section of the leg shaft is an arc. The tripod type constant velocity universal joint according to claim 1, wherein a curve including each contact point on the outer diameter cross section of the leg shaft is formed of a part of an ellipse. A plurality of balls are interposed between the outer raceway surface formed on the inner periphery of the roller and the inner raceway surface formed on the outer periphery of the ring so as to form a deep groove ball bearing or an angular ball bearing. The tripod type constant velocity universal joint according to any one of claims 1 to 3. 2. A plurality of rollers are interposed between the outer raceway surface formed on the inner circumference of the roller and the inner raceway surface formed on the outer circumference of the ring so as to constitute a needle bearing. The tripod type constant velocity universal joint according to any one of items 1 to 3. The tripod type constant velocity universal joint according to any one of claims 1 to 3, wherein the outer peripheral surface of the roller and the roller guide surface are in a circular contact or an angular contact.

Images