JP2007010081A - Fixed type constant velocity universal joint for steering - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixed type constant velocity universal joint for steering capable of realizing a higher operation angle than a conventional operation angle by putting a ball on an outer side of an outer side joint member without dropping the ball. <P>SOLUTION: This fixed type constant velocity universal joint for steering is provided with the outer side joint member 1 like a cup with a shaft forming a plurality of guide channels 1b extending in the axial direction on an inner peripheral face 1a like a spherical face, an inner side joint member 2 forming a plurality of guide channels 2b extending in the axial direction on an outer peripheral face 2a like a spherical face, the balls 4 for transmitting torque arranged one by one in a plurality of ball tracks formed by cooperation of the guide channels 1b of the outer side joint member 1 and the guide channels 2b of the inner side joint member 2, and a cage 5 for storing the balls 4. In this fixed type constant velocity universal joint for steering, window opening dimension on an outer peripheral side of a window 6 of the cage 5 for storing the balls 4 is made smaller than diameter of the ball 4 by overhanging parts 6a2, 6b2 overhanging onto an inner side of the window 6. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fixed type constant velocity universal joint for steering capable of a high bending angle.

  The steering device converts the rotational movement of the steering wheel into the reciprocating movement of the tie rod. A steering column including one or a plurality of steering shafts is provided between the steering wheel and the steering gear for transmission of steering force. Is disposed. If the steering shaft cannot be arranged in a straight line due to the space in the vehicle, etc., one or more shaft couplings can be arranged between the steering shafts so that accurate rotational motion can be transmitted to the steering gear even when the steering shaft is bent. I have to. As this shaft joint, a fixed type constant velocity universal joint is generally used. However, in recent years, from the viewpoint of improving the safety of passengers in the event of a vehicle collision, there has been an increasing demand for a constant operating universal joint for steering. ing.

  As a fixed type constant velocity universal joint, a so-called double offset type constant velocity universal joint obtained by improving a zepper type constant velocity universal joint is known (see Patent Document 1). In this joint, the ball center trajectories of the two guide grooves of the outer joint member and the inner joint member are made into circles with the same radius centered at points that are equidistant from the joint center in the opposite direction of the joint axial direction. is there.

  In this double offset type constant velocity universal joint, when the joint is rotated at a high operating angle, if the ball protrudes outward from the guide groove of the outer joint member, the ball jumps radially outward from the cage window. Can not be prevented. For this reason, in the conventional double offset type constant velocity universal joint, the ball must be stored in the guide groove of the outer joint member. This limits the maximum operating angle of the joint, which is limited to about 48 °. Met.

  In order to further increase the operating angle of the joint, for example, about 60 °, the ball must be taken out from the guide groove of the outer joint member. At that time, if the pair of ball guide surfaces facing in the axial direction of the cage is a plane parallel to the radial direction of the cage, the ball falls out of the cage window, and the constant velocity universal joint Lose functionality.

Japanese Patent Laid-Open No. 2003-130082

  An object of the present invention is to provide a fixed type constant velocity universal joint for a steering which can realize a higher operating angle than that of the prior art by taking it out of an outer joint member without dropping the ball.

  In order to solve the above problems, the invention of claim 1 is directed to a cup-shaped outer joint member with a shaft in which a plurality of guide grooves extending in the axial direction are formed on a spherical inner peripheral surface, and an axial direction on a spherical outer peripheral surface. Torque transmission disposed one by one on a plurality of ball tracks formed by cooperation of an inner joint member formed with a plurality of guide grooves extending in the direction, a guide groove of the outer joint member and a guide groove of the inner joint member In a fixed type constant velocity universal joint for a steering equipped with a ball and a cage for holding the ball, a window opening dimension of an outer peripheral side of a window of the cage for housing the ball is extended by an overhanging portion projecting inside the window. It is smaller than the diameter of the ball.

  In the fixed constant velocity universal joint for steering according to the present invention, the outer joint member and the inner joint member are bent at a high operating angle or a limit operating angle, and the ball positioned outside the bending angle is opened to the outer joint member. Even when protruding from the end to the outside, the window opening dimension on the outer peripheral side of the window is made smaller than the diameter of the ball by the overhanging part that protrudes to the inside of the window, so the ball is held in the guide groove of the inner joint member. And can be prevented from falling radially outward from the window of the cage.

According to a second aspect of the present invention, in the first aspect of the present invention, the outer peripheral spherical surface and the inner peripheral surface of the cage are slidably contacted with the inner peripheral spherical surface of the outer joint member and the outer peripheral spherical surface of the inner joint member, respectively. An inner spherical surface and the ball center locus of the guide groove of the inner joint member is included in a virtual spherical surface located between the outer spherical surface and the inner spherical surface of the cage in the entire movement region of the ball. It is characterized by.
Thereby, the protrusion amount of the ball can be made uniform inside and outside the cage, and the rolling state of the ball can be stabilized.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, an elastic member that urges the inner joint member and the cage in the direction of relative displacement in the axial direction is interposed between the inner joint member and the cage. It is characterized by wearing.

  As a result, the cage is urged to the inner side of the joint, and the inner joint member is urged to the outer side of the joint by the reaction force from the elastic member. As a result, the ball is pressed inward by the protruding portion of the cage window. The backlash gap between the guide groove of the inner joint member and the ball is eliminated. By eliminating this gap, backlash in the rotational direction of the joint is reduced. A slight gap is formed between the inner joint member and the cage so that they can move relative to each other in the axial direction.

  According to a fourth aspect of the present invention, in the first or second aspect of the present invention, an elastic member that urges the outer joint member and the cage in the direction of relative displacement in the axial direction is interposed between the outer joint member and the cage. It is characterized by wearing.

  As a result, the cage is urged to the outer side (or inner side) of the joint by the elastic member, so that the backlash gap between the guide groove of the outer joint member and the ball is eliminated. By eliminating this gap, backlash in the rotational direction of the joint is reduced. A slight gap is formed between the outer joint member and the cage so that they can move relative to each other in the axial direction.

  According to a fifth aspect of the present invention, in the first or second aspect of the present invention, an elastic member that urges the ball and the cage in the direction of relative displacement in the axial direction is interposed between the ball and the cage. Features.

  As a result, the ball is urged toward the joint back side or joint opening side by the elastic member, so that the backlash gap between the guide surface of the cage window and the ball is eliminated, and the ball is The backlash gap between the guide groove of the inner joint member and the ball is also eliminated by being pressed inside the cage by the overhang portion. By eliminating this gap, backlash in the rotational direction of the joint is reduced. A slight gap is formed between the ball and the cage so that both can move relative to each other in the axial direction.

  In the fixed type constant velocity universal joint for steering according to the present invention, the outer window opening size of the cage window is made smaller than the diameter of the ball by the overhanging portion projecting inside the window. Even when the ball is extended outward from the open end, the ball can be held in the guide groove of the inner joint member, and can be prevented from falling out radially outward from the cage window. The operating angle of the inner joint member can be increased to the limit, and this higher operating angle can increase the safety of the passenger at the time of a vehicle collision.

  Further, according to the present invention, since an elastic member that biases the cage and the inner joint member, the outer joint member, or the ball in the direction of relative displacement in the axial direction is interposed, the backlash around the ball Clearance can be eliminated and sure handling can be realized.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. FIG. 1 shows a fixed constant velocity universal joint for steering according to the present invention. FIG. 1 (A) shows a state where the operating angle is 0 °, and FIG. 1 (B) shows a limit operating angle (60 °). State. As shown in FIG. 2, the fixed type constant velocity universal joint includes a cup-shaped outer joint member 1 with a shaft formed by forming eight curved guide grooves 1b in the inner circumferential spherical surface 1a in the axial direction, and an outer circumferential spherical surface 2a. Eight curved guide grooves 2b are formed in the axial direction, an inner joint member 2 having a spline (or serration) hole 2c, a shaft 3 having one end fitted in the spline hole 2c, and an outer joint member 1 It comprises a torque transmission ball 4 arranged one by one on eight ball tracks formed in cooperation with the guide groove 1b and the guide groove 2b of the inner joint member 2, and a cage 5 for holding the ball 4. Is done. Although the number of guide grooves is 8 in the figure, the number of grooves may be increased to 9, 10, 11, 12,.

The fixed type constant velocity universal joint is called a double offset type. As shown in FIG. 1A, the centers O ₁ and O ₂ of the two guide grooves 1b and 2b of the outer joint member 1 and the inner joint member ₂ are With respect to the common center O of the inner peripheral spherical surface 1a of the outer joint member 1 and the outer peripheral spherical surface 2a of the inner joint member 2, they are offset by an equal distance on the opposite side in the axial direction. Thereby, the ball track formed by the cooperation of the guide groove 1b and the guide groove 2b corresponding to the guide groove 1b has a wedge shape opened toward the opening side of the joint.

  As shown in FIG. 1A, when the two axes are not angularly displaced, that is, in a state where the rotation axes of the two axes are in a straight line, the centers of all the torque transmission balls 4 include the joint center O and are perpendicular to the rotation axis. In a flat plane. When the outer joint member 1 and the inner joint member 2 are angularly displaced, for example, by an angle θ as shown in FIG. 1B, the cage 5 causes the torque transmitting ball 4 to be oriented in a plane that bisects the angle θ. This ensures the constant velocity of the joint.

  The cage 5 is formed of an annular member, and the outer peripheral surface thereof is an outer peripheral spherical surface 5 a that is in sliding contact with the inner peripheral spherical surface 1 a of the outer joint member 1, and the inner peripheral surface is in sliding contact with the outer peripheral spherical surface 2 a of the inner joint member 2. The inner peripheral spherical surface 5b is used. The same number of windows 6 as the balls 4 are formed through the peripheral wall of the cage 5 by grinding or milling. The window 6 has a rectangular shape, for example, and is formed at equal intervals in the circumferential direction of the cage 5.

  The inner peripheral surface on the joint inlet side of the cage 5 is a cylindrical surface 5c having a size that allows the inner joint member 2 to be inserted in a coaxial state. A groove portion 5d for fitting the retaining ring 7 after the assembly of the joint is completed is formed on the cylindrical surface 5c. A seat surface member 8 that is in sliding contact with the outer peripheral spherical surface 2 a of the inner joint member 2 is fitted to the cylindrical surface 5 c of the cage 5, and a retaining ring 7 is attached to the outside of the seat surface member 8.

  In the present invention, the outside window opening dimension of the window 6 of the cage 5 is made larger than the diameter of the ball 4 (equal to the distance D1) by the overhanging portions (6a2 and 6b2) protruding inside the window 6 as shown in FIG. It is a little narrower. That is, a pair of ball guide surfaces 6a and 6b opposed to the joint axis direction of the window 6 of the cage 5 are arranged with an inner portion 6a1 of the phantom spherical surface S positioned between the outer circumferential spherical surface 5a and the inner circumferential spherical surface 5b. 6b1 is parallel to each other (distance D1), but the outer surfaces 6a2 and 6b2 of the phantom spherical surface are cylindrical surfaces matching the surface curvature of the ball 4 (minimum distance D2). In FIG. 3, the inner portions 6 a 1 and 6 b 1 of the ball guide surfaces 6 a and 6 b are illustrated in a state of extending slightly outward from the phantom spherical surface S, but this is for equalizing the protruding amount of the ball inside and outside the cage 5. is there. Since the amount of protrusion of the ball inside and outside the cage 5 is not necessarily equal in terms of the function of the joint, the inner portions 6a1 and 6b1 and the outer portions 6a2 and 6b2 may be separated with the phantom spherical surface S as a boundary.

  The ball center locus is included in the phantom spherical surface S located between the outer peripheral spherical surface 5a and the inner peripheral spherical surface 5b of the cage 5 in the entire movement region of the ball 4. As a result, the center of the ball 4 is positioned on the phantom spherical surface S, and the outer periphery of the ball 4 comes into contact with the boundary between the inner portions 6a1 and 6b1 and the outer portions 6a2 and 6b2, which are the starting portions of the curved surfaces of the ball guide surfaces 6a and 6b.

The constant velocity universal joint according to the present invention is configured as described above. When the outer joint member 1 and the inner joint member 2 are at the operating angle of 0 ° in FIG. 1A, the ball 4 is guided by the outer joint member 1. The effect of the offset of the curvature centers O ₁ and O ₂ of the groove 1b and the guide groove 2b of the inner joint member 2 is held in a plane including the joint center O and perpendicular to the rotation axis, and torque is transmitted in this state.

  Next, in a state where the outer joint member 1 and the inner joint member 2 are bent to the limit operating angle θ as shown in FIG. 1B, the shaft 3 contacts the open end of the outer joint member 1. The torque transmission ball 4 is oriented in a plane that bisects the angle θ by the cage 5, thereby ensuring constant velocity of the joint. At this time, even if the ball 4 positioned outside the bending angle exits from the opening end of the outer joint member 1, the constant velocity universal joint of the present invention sets the window opening dimension D 2 of the outer periphery side of the window 6 to the diameter of the ball 4. Since it is smaller than (D1), the ball 4 does not fall out radially outward from the window 6 of the cage 5. Accordingly, the ball 4 is held in the guide groove 2b of the inner joint member 2, and enters the guide groove 1b of the outer joint member 1 again as the joint rotates.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and can be variously modified. Below, the modification of this invention is demonstrated in order based on FIGS. Each of these modified examples eliminates the backlash gap around the ball and realizes a sure handling.

  FIG. 4 shows a cylindrical elastic member 11 that urges the inner joint member 2 and the cage 5 in a direction relatively spaced apart in the axial direction between the inner joint member 2 and the cage 5, and the elastic member. 11 is provided with a dish-like member 12 for causing the force of 11 to act on the cage 5. As the elastic member 11, a coil spring or the like can be employed in addition to various synthetic rubbers such as natural rubber and urethane rubber. The base of the elastic member 11 is fixedly fitted into the tip recess 3 a of the shaft 3, and the tip of the elastic member 11 extends toward the back side of the outer joint member 1. The dish-shaped member 12 is fitted on the tip of the elastic member 11 with the concave surface thereof facing the elastic member 11, and the tip of the elastic member 11 is slidably brought into contact with the center of the dish-shaped member 12. If necessary, a low-friction material such as Teflon (registered trademark) of fluororesin (registered trademark of DuPont, USA) is attached to the distal end surface of the elastic member 11. The peripheral edge portion of the dish-like member 12 is engaged with a step portion 5 e formed on the inner diameter of the joint inner side of the cage 5. The concave surface of the dish-shaped member 12 is a spherical surface centering on the center O of the joint, and continuously extends with the same curvature as the outer peripheral spherical surface 2 a of the inner joint member 2. A predetermined compressive force is applied to the elastic member 11 at an initial setting, and the restoring extension force of the elastic member 11 acts on the cage 5 as a biasing force in a direction relatively away from the inner joint member 2.

  According to the first modification, as a result of the inner joint member 2 being urged to the outer side of the joint by the reaction force from the elastic member 11, a backlash gap between the guide groove 2 b of the inner joint member 2 and the ball 4 is generated. It will be resolved.

  In FIG. 5, a cup-shaped elastic member 13 is interposed between the outer joint member 1 and the cage 5 to bias the outer joint member 1 and the cage 5 away from each other in the axial direction. It is. As the elastic member 13, a coil spring or the like can be employed in addition to various synthetic rubbers such as natural rubber and urethane rubber. The shaft-like base portion 13 a of the elastic member 13 is fitted into the back side recess 1 c of the outer joint member 1, and the cup portion 13 b of the elastic member 13 extends inside the outer joint member 1. The spherical convex surface of the bowl-shaped member 14 is slidably fitted to the spherical concave surface of the cup portion 13 b, and the peripheral edge portion of the bowl-shaped member 14 is engaged with a stepped portion 5 f formed on the joint back side of the cage 5. To do. The center of curvature of the spherical concave surface of the cup portion 13b or the spherical convex surface of the bowl-shaped member 14 coincides with the center O of the joint. If necessary, a low friction material such as Teflon (registered trademark) of fluororesin (registered trademark of DuPont, USA) is attached to the spherical concave surface of the cup portion 13b. Note that the cup portion 13b is not integral with the elastic member 13, but may be a separate metal or resin member. In this case, the shaft-like base portion 13a and the cup portion 13b are integrally connected by fitting, bonding or screwing.

  According to the second modified example, the cage 5 is urged to the outer side of the joint by the elastic member 13, so that the backlash gap between the guide groove 1 b of the outer joint member 1 and the ball 4 is eliminated.

  In FIG. 6, an elastic member 15 that biases the ball 4 and the cage 5 in the direction of relative displacement in the axial direction is interposed between the ball 4 and the cage 5. As the elastic member 15, various synthetic rubbers such as natural rubber and urethane rubber can be employed. That is, the step part 6c is formed in the outer-diameter side edge part of the window 6 of the holder | retainer 5, and the elastic member 15 is fitted so that this step part 6c may be embedded. A slight gap allowing such a displacement of the ball is provided between the ball 4 and the cage 5. The inner surface of the elastic member 15 projects so that the outer window opening dimension of the window 6 is narrower than that in the state of FIG. 3 in the initial state before the ball 4 is fitted. By fitting the ball 4, the inner surface of the elastic member 15 is slightly compressed and becomes equal to the state of FIG. 3. In this state, the restoring force of the elastic member 15 acts on the ball 4 as an urging force in the left direction in FIG. If necessary, a low friction material such as Teflon (registered trademark) of fluororesin (registered trademark of DuPont, USA) is attached to the inner surface of the elastic member 15.

  According to the third modification, the ball 4 is urged toward the joint back side by the elastic member 15, so that the backlash gap between the guide surface 6 a of the window 6 of the cage 5 and the ball 4 is eliminated. .

  Although the embodiments and modifications of the present invention have been described above, the present invention is not limited to the embodiments or modifications, and various modifications can be made based on the technical idea described in the claims. Thus, for example, it is possible to combine two arbitrary examples of the three modifications shown in FIGS. 4 to 6 or a combination of all three examples.

(A) and (B) are longitudinal sectional views of a fixed type constant velocity universal joint for steering according to the present invention. 1 is a cross-sectional view of a fixed type constant velocity universal joint for steering according to the present invention. FIG. The longitudinal cross-sectional view of the fixed type constant velocity universal joint for steerings concerning the 1st modification of this invention. The longitudinal section of the fixed type constant velocity universal joint for steering concerning the 2nd modification of the present invention. The longitudinal cross-sectional view of the fixed type constant velocity universal joint for steerings concerning the 3rd modification of this invention.

Explanation of symbols

1 outer joint member 1a inner joint spherical surface 1b outer joint member guide groove 2 inner joint member 2a inner joint member outer circumferential spherical surface 2b inner joint member guide groove 2c inner joint member spline hole 3 shaft 4 torque transmission ball DESCRIPTION OF SYMBOLS 5 Retainer 5a Retainer outer peripheral spherical surface 5b Retainer inner peripheral spherical surface 5c, 5d Retainer step 6 Retainer window 6a, 6b Window ball guide surface 6a1, 6b1 Inner portion 6a2, 6b1 of ball guide surface Outer portion 7 of guide surface Retaining ring 8 Seat surface members 11, 13, 15 Elastic member 12 Dish-shaped member 14 Gutter-shaped member S Virtual spherical surface

Claims (5)

  A cup-shaped outer joint member with a shaft in which a plurality of guide grooves extending in the axial direction are formed on the spherical inner peripheral surface, and an inner joint member in which a plurality of guide grooves extending in the axial direction are formed on the spherical outer peripheral surface; A torque transmitting ball disposed on each of a plurality of ball tracks formed in cooperation by the guide groove of the outer joint member and the guide groove of the inner joint member; and a cage for holding the ball. In a fixed constant velocity universal joint for steering, the window opening dimension of the outer peripheral side of the window of the cage that accommodates the ball is made smaller than the diameter of the ball by an overhanging portion that protrudes to the inside of the window. Fixed type constant velocity universal joint.   The outer peripheral surface and the inner peripheral surface of the cage are an outer peripheral spherical surface and an inner peripheral spherical surface that are in sliding contact with the inner peripheral spherical surface of the outer joint member and the outer peripheral spherical surface of the inner joint member, respectively, and the guide groove of the inner joint member 2. The fixed constant velocity for steering according to claim 1, wherein the ball center trajectory is included in a virtual spherical surface located between the outer peripheral spherical surface and the inner peripheral spherical surface of the cage in the entire movement region of the ball. Universal joint.   The fixing for steering according to claim 1 or 2, wherein an elastic member for biasing the inner joint member and the cage in the direction of relative displacement in the axial direction is interposed between the inner joint member and the cage. Type constant velocity universal joint.   3. The steering fixing according to claim 1, wherein an elastic member for biasing the outer joint member and the cage in the direction of relative displacement in the axial direction is interposed between the outer joint member and the cage. Type constant velocity universal joint.   The fixed type constant velocity universal for steering according to claim 1 or 2, wherein an elastic member for biasing the ball and the cage in the direction of relative displacement in the axial direction is interposed between the ball and the cage. Fittings.

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