JP2005133890A - Tripod type constant velocity universal joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tripod-type constant velocity universal joint capable of remarkably reducing the number of components and assembling man-hour, and free from the impairing of NVH performance by superior roller rolling characteristic. <P>SOLUTION: In this tripod type constant velocity universal joint 1, the contour shape of an outer-diameter face of a trunnion journal 2a is non-circular, and a contact position O' of the outer-diameter face of the trunnion journal 2a and an inner-diameter face of a roller 5 directly fitted to the outer-diameter face of the trunnion journal 2a is shifted from a vertical line V drawn from a center O of the trunnion journal 2a to a track groove 3 of an outer ring, to a position separated by a specific distance in the longitudinal direction of the track groove 3. The contour shape of the outer-diameter face of the trunnion journal 2a is the contour shape C1 of a moving locus of an ellipse in offsetting the ellipse by a specific distance in the minor-axial direction, or the contour shape C2 of the moving locus of the ellipse in rotating the ellipse on its center by a specific angle. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a sliding tripod type constant velocity universal joint used for power transmission of automobiles and various industrial machines.

  Constant velocity universal joints transmit torque between two non-linear rotating shafts. Sliding tripod type constant velocity universal joints are widely used in the drive system of front-engine front-wheel drive vehicles (FF vehicles). The

  This sliding tripod type constant velocity universal joint 1 ′ has a tripod member 2 including three trunnion journals 2 b protruding in the radial direction as shown in FIG. The tripod member 2 is coupled to one shaft connected to the hub wheel in the FF automobile. Also, a bottomed cylindrical outer ring 4 having three track grooves 3 is coupled to the other shaft such as an output shaft of the transmission. A roller 5a rotatably fitted to the trunnion journal 2a is accommodated in the track groove 3 so as to be axially displaceable and transmits torque between the two shafts.

  A rolling element such as a needle roller 6 is disposed between the trunnion journal 2 a and the roller 5. The needle rollers 6 are generally disposed in a full roller state and are secured by a retaining ring 7a. The track groove 3 has a pair of roller guide surfaces 3a opposed in the circumferential direction. The roller guide surface 3a is a concave curved surface parallel to the axial direction, and the outer diameter surface of the roller 5 is a convex curved surface adapted to the roller guide surface 3a.

  When the torque is transmitted with the tripod type constant velocity universal joint 1 ′ having the operating angle, the roller 5 a and the roller guide surface 3 a are in an oblique relationship. For this reason, a slip occurs between the roller guide surface 3a and the roller 5a, and a sliding resistance and an axially induced thrust due to the slip are generated. These slide resistance and induced thrust adversely affect the NVH performance of the automobile.

  As a sliding tripod type constant velocity universal joint with reduced sliding resistance and induced thrust, for example, a low vibration type constant velocity universal joint 1 ″ shown in FIG. 7B is known (see Patent Document 1). This constant velocity universal joint 1 '' is fitted with a trunnion journal 2c having an outer diameter surface formed in an elliptical cylinder, for example, so that the inner roller 5b can slide and swing. An outer roller 5c is rotatably fitted to the outer diameter surface of the inner roller 5b via needle rollers 6 in a full roller state. That is, the roller rolling kit K as shown in FIG. 8 is fitted to the trunnion journal 2c of the low vibration type constant velocity universal joint 1 ″. The roller rolling kit K has a triple structure of an inner roller 5b, a needle roller 6, and an outer roller 5c. The needle roller 6 is secured by a pair of upper and lower retaining rings 7b. The outer roller 5c is accommodated in the track groove 3 so as to be axially displaceable in the same manner as the constant velocity universal joint of FIG.

 In this low-vibration type constant velocity universal joint 1 ″, the inner roller 5b, and hence the outer roller 5c, can swing with respect to the trunnion journal 2c, so that the outer roller 5c and the roller guide surface 3a can be used even when a certain operating angle is taken. Are not in an oblique relationship, and the generation of slide resistance and induced thrust is suppressed.

JP 2000-320563 A

In the conventional sliding tripod type constant velocity universal joints 1 ′ and 1 ″, the roller rolling kit K is constituted by the needle roller 6 and the roller 5a (in the low vibration type, the inner roller 5b and the outer roller 5c). Such conventional constant velocity universal joints have the following problems because they employ needle rollers as rolling elements.
1. A double structure of needle rollers and rollers, or a triple structure of inner rollers, needle rollers, and outer rollers increases the number of parts, resulting in increased part costs and assembly costs.
2. The needle rollers are arranged in a full roller state, but since the contact surface pressure is high, considering the durability, the diameter and the shaft length of the needle rollers cannot be reduced, and there is a limit to downsizing.
3. In order to improve the durability, there is a method of improving the surface roughness of the rolling surface of the needle roller, but the processing cost for improving the surface roughness increases.

  The present invention solves these problems, and by omitting rolling elements such as needle rollers, the number of parts and the number of assembling steps can be greatly reduced, and the NVH performance is impaired by good roller rolling characteristics. An object of the present invention is to provide a tripod type constant velocity universal joint.

  In order to solve the above problems, the present invention makes the contour shape of the outer diameter surface of the trunnion journal of the tripod type constant velocity universal joint non-circular, and directly fits the outer diameter surface of the trunnion journal and the outer diameter surface of the trunnion journal. The contact position with the inner diameter surface of the combined roller is moved from a perpendicular line dropped from the center of the trunnion journal to the track groove of the outer ring to a position separated by a predetermined distance in the longitudinal direction of the track groove. To do.

  That is, in order to reduce the cost and size of the tripod type constant velocity universal joint, the rolling elements such as needle rollers are omitted and the inner surface of the roller is directly fitted to the trunnion journal so as to be rotatable. To compensate for the reduction in roller rolling characteristics due to omission, the contact point between the trunnion journal and the inner diameter surface of the roller is changed from the conventional outer ring circumferential direction to the roller movement direction (axial direction of the outer ring or longitudinal direction of the track groove). Is shifted by a predetermined distance.

  If the needle roller is simply omitted, the rotation of the roller is suppressed by the slip resistance between the trunnion journal and the inner diameter surface of the roller, which adversely affects the NVH characteristics (noise, vibration, roughness). Therefore, in the constant velocity universal joint of the present invention, the position of the contact point between the trunnion journal and the inner diameter surface of the roller is changed in order to promote the rotation of the roller.

  In order to shift the contact point between the trunnion journal and the inner diameter surface of the roller, the contour shape of the outer diameter surface of the trunnion journal is made noncircular. Here, “non-circular” is typically the contour shape of the moving locus of the ellipse when the ellipse is offset by a predetermined distance in the minor axis direction, or the ellipse is rotated around the center by a predetermined angle. It is the outline shape of the movement locus of the ellipse when However, the “non-circular shape” may be any other shape as long as the contact point between the trunnion journal and the inner diameter surface of the roller is shifted by a predetermined distance from the circumferential direction of the outer ring to the moving direction of the roller.

When the cross-section of the trunnion journal has the above shape, the trunnion journal comes into contact at two points. During reciprocation, the load ratio at two points changes. Considering the contact point on the side receiving more load, it can be considered as follows. A mechanism for rotating the roller will be described with reference to FIG. FIG. 3 shows a cross section of the trunnion journal 2 a and the roller 5. In addition, the code | symbol used in FIG. 3 is as follows.
Q: Force that the trunnion journal 2a pushes the inner diameter surface of the roller 5 vertically F: Force that the trunnion journal 2a slides the roller 5 along the outer ring track groove 3 (Q horizontal component)
P: force by which the trunnion journal 2a presses the roller 5 against the outer ring track groove 3 (Q vertical component)
μ: friction coefficient between the roller 5 and the outer ring track groove 3 Point C: tip of a contact ellipse e generated between the roller 5 and the outer ring track groove 3 (fulcrum when the roller rotates)
Point O: Center point of trunnion journal 2a Point O ': Contact point between trunnion journal 2a and inner surface of roller 5 a: Shortest distance in the outer ring circumferential direction from point O' to point C b: From point O 'to point C The shortest distance in the outer ring axial direction

  Here, the roller 5 slides in the direction of F when F> μP, and the roller is stationary when F ≦ μP, because of the force relationship of the outer ring in the track groove 3 direction (joint axis direction).

  In relation to the moment with the point C of the roller 5 as a fulcrum, when aF> bP, a moment in the clockwise direction acts on the roller 5, and when aF <bP, a moment in the counterclockwise direction is applied to the roller 5.

The behavior of the roller 5 is summarized as shown in Table 1 below.

  In the upper right column of Table 1, that is, when F ≦ μP and aF> bP, the roller 5 rolls and moves on the outer ring track groove 3 without sliding.

  From the above, the contact position of the inner diameter surface of the roller 5 directly fitted to the outer diameter surface of the trunnion journal 2a is changed from the vertical line V drawn from the center of the trunnion journal 2a to the track groove 3 of the outer ring to the track groove 3. It is proved that the roller 5 can be rolled and moved without slipping in the longitudinal direction of the track groove 3 without a rolling element by being separated by a predetermined distance in the longitudinal direction.

Since the present invention is configured as described above,
1. By setting the contact point between the trunnion journal and the inner diameter part of the roller to two points, the load is dispersed and the surface pressure is lowered, so that the wear of the trunnion journal can be reduced.
2. By making the contact position between the trunnion journal and the inner diameter part of the roller shifted from the circumferential direction of the conventional outer ring in the roller traveling direction, the roller can easily roll, and even if a rolling element such as a needle roller is omitted The NVH characteristics required for the constant velocity universal joint can be maintained.
3. The tripod type constant velocity universal joint can be composed of three types of parts, trunnion, roller and outer ring, and the manufacturing cost and assembly cost can be reduced by reducing the number of parts.
4). By omitting rolling elements such as needle rollers, a space margin is created inside the joint, and the degree of freedom of reinforcing the strength surface, such as increasing the thickness of each component by using this space margin, is increased.
5). The outer ring can be reduced in size and weight by reducing the size of each part by utilizing the space allowance, and the cost can be reduced accordingly.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows a cross section of the sliding tripod type constant velocity universal joint 1 of the present invention applied to the drive system of the FF automobile. In this tripod type constant velocity universal joint 1, a tripod member 2 including three trunnion journals 2a projecting in the radial direction is connected to an outboard shaft (not shown) connected to a hub wheel. A bottomed cylindrical outer ring 4 having three track grooves 3 extending in the axial direction is connected to an inboard side shaft (not shown) connected to the output shaft of the transmission.

  A roller 5 which is directly fitted to the trunnion journal 2a so as to be rotatable is accommodated in the track groove 3 so as to be axially displaceable. The pair of roller guide surfaces 3a facing the circumferential direction of the track groove 3 is formed of a part of a cylindrical surface. The outer diameter surface of the roller 5 is a spherical surface adapted to the roller guide surface 3a. Due to the circumferential engagement of the roller 5 and the track groove 3, torque transmission from the transmission output shaft to the hub wheel is performed.

  As shown in FIG. 1, the outline of the outer diameter surface of the trunnion journal 2a is not a circular shape as shown in FIG. 7A, an ellipse as shown in FIG. This is the contour C1 of the movement locus of the ellipse E when offset in the minor axis direction (hereinafter, this contour C1 is referred to as “offset ellipse contour C1”). The circular inner diameter surface of the roller 5 is fitted to the outer diameter surface of the trunnion journal 2a. Accordingly, the four points P1 to P4 on the outer diameter surface of the trunnion journal 2a come into contact with the inner diameter surface of the roller 5. Points P1 to P4 are located in a direction in which the ellipse is offset from the long axes L1 and L2 of the ellipse E.

  FIG. 4 is a modified example of the contour C2 of the outer diameter surface of the trunnion journal 2a. When the ellipse E is rotated to the right or left by a predetermined angle around its center O (intersection of major and minor axes). This is the contour of the movement locus of the ellipse E (hereinafter, this contour C2 is referred to as “rotating ellipse contour C2”). When the circular inner diameter surface of the roller 5 is directly and rotatably fitted to the outer diameter surface of the trunnion journal 2a, the four points P1 to P4 on the outer diameter surface of the trunnion journal 2a come into contact with the inner diameter surface of the roller 5. . The four points P1 to P4 overlap with the major axis L of the ellipse.

  As shown in FIG. 5, when the angle formed by the straight line connecting the center of the ellipse E and the point with the major axis L of the ellipse E is θ, the value of θ is desirably 5.8 ° shown in FIG. And between 9 ° shown in FIG. 5B (including angles at both ends). When θ <5.8 °, it tends to be “still” in the lower right column of Table 1, and when 9 ° <θ, it is changed to “Right rotation rolling slip” in the upper left column of Table 1 or “No rotation slip” in the lower left column. Prone. These 5.8 ° and 9 ° were calculated from the conditions of F ≦ μP and aF> bP.

  6A and 6B are cross-sectional views of a tripod type constant velocity universal joint. The cross-sectional shape of the trunnion journal 2a of this constant velocity universal joint is an offset elliptical contour or a rotating elliptical contour.

  FIG. 6A is a cross-sectional view of a constant velocity universal joint in which the inner diameter of the roller 5 is an axial cross section and an arcuate convex cross section. Since the trunnion journal 2a has a cross-sectional shape offset or rotated from the ellipse E, and the inner diameter of the roller 5 is an arc-shaped convex cross section, the track groove 3 is formed between the trunnion journal 2a and the roller 5. A relatively large gap G1 is formed in the longitudinal direction. Due to the presence of the gap G1 and the clearance above and below the roller 5, the roller 5 can move in the axial direction of the trunnion journal 2a as indicated by an arrow in FIG. 6A, and the neck in the left-right direction with respect to the trunnion journal 2a. Swinging is possible. As a result, the oblique relationship between the roller 5a and the track groove 3 when the tripod type constant velocity universal joint rotates at the operating angle is relaxed, and the NVH performance is prevented from being impaired.

  FIG. 6B is a cross-sectional view of a constant velocity universal joint in which the inner diameter of the roller 5 is cylindrical and the cross section in the axial direction is a straight line. Also in this constant velocity universal joint, the trunnion journal 2a has a cross-sectional shape offset or rotated from the ellipse E, and a gap G2 exists between the trunnion journal 2a and the roller 5. Due to the presence of the gap G2 and the clearance above and below the roller 5, the roller 5 can move in the axial direction of the trunnion journal 2a as indicated by the arrow in FIG. Swing is possible. As a result, the oblique relationship between the roller 5b and the track groove 3 when the tripod type constant velocity universal joint rotates with the operating angle is relaxed, and the NVH performance is prevented from being impaired.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the technical idea described in the claims. The structures or treatments that can be added to the tripod type constant velocity universal joint of the present invention as required are listed below.
1. In order to stabilize the posture of the roller 5, the outer diameter surface of the roller 5 is a spherical surface, and this roller 5 is in angular contact with the track groove of the outer ring.
2. In order to improve the durability of the trunnion journal 2a, heat treatment is applied to the outer diameter surface to increase the hardness.
3. The outer surface and / or inner surface of the roller 5 is subjected to a surface treatment such as spraying for abrasion resistance or low friction, plating, or application of a sliding material.
4). The track groove 3 of the outer ring 4 is subjected to a surface treatment such as thermal spraying, plating, or application of a sliding material for wear resistance or low friction.
5). An oil groove for facilitating the intervention of the lubricant is provided on the outer diameter surface of the trunnion journal 2a.
6). An oil groove that facilitates intervention of the lubricant is provided in the inner diameter portion and / or outer diameter portion of the roller 5.
7). An oil groove that facilitates the intervention of the lubricant is provided in the track groove 3 of the outer ring 4.
8). Of the outer diameter surface of the trunnion journal 2a, only the region in contact with the inner diameter surface of the roller 5 is ground to reduce the friction coefficient and improve the durability.

The cross-sectional outline figure of the trunnion journal of the tripod type | mold constant velocity universal joint which concerns on this invention. Sectional drawing of the tripod type | mold constant velocity universal joint which concerns on this invention. FIG. 5 is a cross-sectional view in the axial direction of an outer ring track groove for explaining a roller rolling mechanism. The cross-sectional outline figure of the trunnion journal of the tripod type | mold constant velocity universal joint which concerns on the modification of this invention. (A) (B) is a cross-sectional view of a trunnion journal and a roller. (A) and (B) are axial direction sectional views of an outer ring and a roller. (A) and (B) are sectional views of a conventional tripod type constant velocity universal joint. Sectional drawing of the roller rolling kit of the conventional tripod type constant velocity universal joint.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sliding tripod type constant velocity universal joint 2 Tripod member 2a Trunnion journal 3 Track groove 3a Roller guide surface 4 Outer ring 5 Roller 6 Needle roller 7a Retaining ring 7b Retaining ring

Claims (16)

  The outer diameter surface of the trunnion journal of the tripod constant velocity universal joint is made non-circular, and the outer diameter surface of the trunnion journal and the inner diameter surface of the roller that is rotatably fitted directly to the outer diameter surface of the trunnion journal. The tripod type constant velocity universal joint is characterized in that the contact position is set at a position spaced apart from the perpendicular line from the center of the trunnion journal to the track groove of the outer ring by a predetermined distance in the longitudinal direction of the track groove.   The tripod type constant velocity according to claim 1, wherein the contour shape of the outer diameter surface of the trunnion journal is the contour shape of the movement trajectory of the ellipse when the ellipse is offset by a predetermined distance in the minor axis direction. Universal joint.   2. The tripod constant velocity according to claim 1, wherein the contour shape of the outer diameter surface of the trunnion journal is a contour shape of a movement locus of the ellipse when the ellipse is rotated by a predetermined angle around its center. Universal joint.   4. A predetermined gap that allows the roller to swing is formed between an outer diameter surface of the trunnion journal and an inner diameter surface of the roller in a longitudinal direction of the track groove. The tripod type constant velocity universal joint described.   The tripod type according to claim 4, wherein the inner surface of the roller has an arcuate convex shape having a smaller inner diameter at the center in the axial direction than the inner diameter at both ends of the trunnion journal in the axial direction. Constant velocity universal joint.   The tripod type constant velocity universal joint according to claim 2 or 3, wherein an outer diameter surface of the roller is a spherical surface, and the roller is in angular contact with a track groove of the outer ring.   2. The tripod type constant velocity free according to claim 1, wherein the outer diameter surface of the trunnion journal is subjected to surface treatment such as thermal spraying, plating, or adhesion of a sliding material for wear resistance or low friction. Fittings.   The tripod type constant velocity universal joint according to claim 1, wherein the outer diameter surface of the trunnion journal is subjected to heat treatment for increasing hardness.   The tripod type constant velocity universal joint according to claim 1, wherein the outer surface of the roller is subjected to a surface treatment such as thermal spraying, plating, or application of a sliding material for wear resistance or low friction. .   The tripod type constant velocity universal joint according to claim 1, wherein the inner diameter portion of the roller is subjected to a surface treatment such as thermal spraying, plating, or application of a sliding material for wear resistance or low friction.   The tripod type constant velocity universal joint according to claim 1, wherein the track groove of the outer ring is subjected to surface treatment such as thermal spraying, plating, sliding material sticking for wear resistance or low friction.   The tripod type constant velocity universal joint according to claim 1, wherein an oil groove for promoting intervention of a lubricant is provided on an outer diameter surface of the trunnion journal.   The tripod type constant velocity universal joint according to claim 1, wherein an oil groove for promoting intervention of a lubricant is provided in an inner diameter portion and / or an outer diameter portion of the roller.   The tripod type constant velocity universal joint according to claim 1, wherein an oil groove for promoting intervention of a lubricant is provided in a track groove of the outer ring.   2. The tripod constant velocity universal joint according to claim 1, wherein only a region of the outer diameter surface of the trunnion journal that is in contact with the inner diameter surface of the roller is ground.   The contact position between the outer diameter surface of the trunnion journal and the inner diameter surface of the roller is 5.8 ° or more in the circumferential direction of the roller with reference to a perpendicular line dropped from the center of the trunnion journal to the track groove of the outer ring. The tripod type constant velocity universal joint according to claim 1, wherein the tripod type constant velocity universal joint is separated by 9 ° or less.