JP4298529B2 - Fixed type constant velocity universal joint - Google Patents

Description

  The present invention relates to a fixed type constant velocity universal joint, and more particularly to a fixed type constant velocity universal joint incorporated in a steering device of an automobile.

  Constant velocity universal joints are broadly classified into fixed types that allow only angular displacement between the input and output shafts, and sliding types that allow angular displacement and axial displacement. Each model is selected according to the application and usage conditions. The As a fixed type constant velocity universal joint, a Rzeppa type (hereinafter referred to as “BJ”) and an undercut free type (hereinafter referred to as “UJ”) are widely known.

  Both BJ and UJ are incorporated between an outer ring having a plurality of curved track grooves on the inner periphery, an inner ring having a plurality of curved track grooves on the outer periphery, and a track groove of the outer ring and a track groove of the inner ring. And a cage for holding the ball. The outer ring track groove center is located on the outer ring opening side with respect to the outer ring inner spherical center, and the inner ring track groove center is located on the outer ring rear side with respect to the inner ring outer spherical center, and is offset by an equal distance in the opposite direction in the axial direction. is doing. Thereby, the ball track constituted by the track groove of the outer ring and the track groove of the inner ring has a wedge shape that expands toward the opening side of the outer ring. In BJ, the entire area of each track groove is curved, whereas in UJ, one end of each track groove is in a straight shape parallel to the axis.

  Generally, two or more cardan joints are used for a shaft joint incorporated in an automobile steering device. Since this joint is not uniform at a single unit, it is arranged and used so as to cancel each other's fluctuation components in order to ensure constant velocity. For this reason, there exists a problem that the design freedom of a vehicle is impaired. By using a constant velocity universal joint that can ensure constant velocity at an arbitrary angle as a steering shaft joint, it is possible to increase the design freedom of the vehicle, but the constant velocity universal joint has a large amount of play in the rotation direction, There is a concern that the steering operation feeling near the vehicle will be deteriorated and abnormal noise may be caused. In order to solve this, it has been proposed to provide a preload means inside the constant velocity universal joint to close the track groove clearance (see, for example, Patent Document 1).

The fixed type constant velocity universal joint has a gap between the outer ring track groove and the inner ring track groove due to the function and machining surface, and the inner ring outer sphere, cage outer sphere, outer ring outer ring There is also a gap between the spherical surface and the inner spherical surface of the cage. These clearances refer to the amount of movement when either the inner ring or outer ring is fixed and the other is moved in the radial or axial direction in the neutral state of the joint. Depending on the direction of movement, radial clearance, axial clearance, etc. Called. These clearances greatly affect the circumferential play (rotational backlash) between the inner and outer rings, and the larger the track groove clearance, the greater the rotational backlash. For this reason, it is unavoidable that the rotation backlash exceeds a certain level. Therefore, this type of fixed type constant velocity universal joint is generally adopted for applications that do not like the rotation backlash, such as an automobile steering device. Not in.
Japanese Patent Laid-Open No. 2003-130082

  By the way, the invention described in the above-mentioned Patent Document 1 is a fixed type constant velocity universal joint for the purpose of filling rotary backlash, and a preload means is provided inside the constant velocity universal joint so as to close the track groove clearance. I have to. In this Patent Document 1, there is provided a preloading means in which a pressing portion for applying an elastic pressing force in the axial direction is provided on the inner member side, and a receiving portion for receiving the pressing force from the pressing portion is provided on the cage side. It is disclosed. In addition, the code | symbol attached | subjected below is described in patent document 1. FIG.

  As one form of the preloading means, a cylindrical housing member 17 is embedded at the shaft end of the shaft 5 coupled to the inner periphery of the inner ring 2 constituting the inner member, and a pressing member is provided inside the housing member 17. 10 and the elastic member 12 are accommodated. The end face of the head portion of the pressing member 10 is formed in a convex spherical shape, and this convex spherical portion functions as the pressing portion 11 that applies an elastic pressing force in the axial direction. On the other hand, a receiving member 14 having a concave spherical surface portion 14 a facing the shaft 5 is attached to the end portion of the cage 4, and the concave spherical portion of the receiving member 14 receives the pressing force from the pressing portion 11. It functions as a receiving portion 15 (see paragraph number [0033] of FIG. 5 and Patent Document 1).

  In the above-mentioned Patent Document 1, the cylindrical housing member 17 is embedded in a recessed portion formed at the shaft end of the shaft 5, and the head portion of the pressing member 10 is a spherical portion of the receiving member 14. 14a is prevented from rotating backlash. However, when the recess is formed at the shaft end of the shaft 5, the depth varies due to the processing tolerance of the recess. Therefore, when the housing member 17 is embedded in the recess, the pressing member is pressed from the shaft end surface of the shaft 5. Variation occurs in the protruding length of the head of the ten. If there is such a variation, the contact state between the head portion of the pressing member 10 and the spherical surface portion 14a of the receiving member 14 is not fixed, and there is a case where the elastic force by the elastic member 12 does not act, thereby reliably preventing rotational backlash. It can be difficult to do.

  Therefore, the present invention has been proposed in view of the above-described problems, and the object of the present invention is to improve the structure of the preload means including the pressing portion and the receiving portion disclosed in Patent Document 1, and It is an object of the present invention to provide a fixed type constant velocity universal joint that can stabilize an attachment state and reliably apply an appropriate preload.

As technical means for achieving the above-mentioned object, the present invention provides an outer member having a spherical inner surface in which a plurality of track grooves are formed, and an inner member having a spherical outer surface in which a plurality of track grooves are formed. A member, a ball disposed on a wedge-shaped ball track formed by cooperation of a track groove of the outer member and a track groove of the inner member, and a spherical inner surface of the outer member and a spherical outer surface of the inner member. And a retainer for holding the ball, the pressing portion for applying an elastic pressing force in the axial direction on the inner member side, and the receiving portion for receiving the pressing force from the pressing portion on the cage side In the fixed type constant velocity universal joint having preload means provided on the plunger unit, the plunger unit having the pressing portion formed at the tip thereof is assembled to the recessed portion formed on the inner member side, and the flange of the plunger unit is connected to the inner member. Engage with the end face And by, characterized by being positioned and fixed relative to the end face of the inner member side.

  In the fixed type constant velocity universal joint according to the present invention, when the plunger unit having the pressing portion formed at the tip thereof is assembled into the recessed portion formed on the inner member side by press-fitting or bonding, the plunger unit is disposed on the inner member side. Position and fix with reference to the end face. As a result, even if there is variation in the depth due to the processing tolerance of the concave portion described above, the mounting state of the pressing portion can be stabilized and the contact state between the pressing portion and the receiving portion can be made constant at all times. The elastic force by the elastic member from the pressing part can be reliably applied to the part.

  The plunger unit in the configuration described above has a pressing member having a pressing portion at the tip, an elastic member that elastically biases the pressing member toward the receiving portion, and a bottomed cylindrical shape that houses the pressing member and the elastic member. It is desirable that the assembly body be an assembly body in which a locking portion having an inner diameter smaller than the outer diameter of the pressing member is provided at the opening end of the housing member. Thus, if the latching | locking part of a press member is provided in the opening end of a storage member, it can prevent that the press member pulls out from a storage member, Moreover, as an assembly body which consists of a press member, an elastic member, and a storage member Can be unitized.

  The aforementioned locking portion is formed by caulking all or part of the opening end of the housing member along the circumferential direction, or by joining a member different from the housing member to the opening end of the housing member. Is possible. In this way, the structure for preventing the pressing member from being pulled out can be realized with a simple configuration.

  If the fixed type constant velocity universal joint described above is incorporated in a steering apparatus of an automobile, it will exhibit a more remarkable effect in preventing the rotation backlash by closing the track groove clearance in the constant velocity universal joint. The automobile steering apparatus may be an electric power steering apparatus that applies a steering assist force by a motor, or may be a hydraulic power steering apparatus.

  According to the present invention, the plunger unit having the pressing portion formed at the tip thereof is positioned and fixed with reference to the end surface on the inner member side, so that the mounting state of the pressing portion is stabilized and the pressing portion and the receiving portion are Since the contact state can be made constant at all times, the preload can be reliably applied by reliably acting on the receiving portion of the elastic force from the pressing portion by the elastic member. Therefore, since the track groove clearance in the constant velocity universal joint can be filled and the rotation backlash can be reliably prevented, a highly reliable fixed type constant velocity universal joint can be provided.

  An embodiment of a fixed type constant velocity universal joint according to the present invention will be described in detail. In the following embodiments, a case where the present invention is applied to a Rzeppa type (BJ) which is a kind of a fixed type constant velocity universal joint for steering is illustrated, but the present invention is not limited to this, and an undercut free type (UJ) It is also applicable to. Further, the fixed type constant velocity universal joint of the present invention is not limited to steering, but can be used for a drive shaft or a propeller shaft.

  First, a steering device incorporating a fixed type constant velocity universal joint will be briefly described. As shown in FIGS. 13A to 13C, the steering device transmits the rotational motion of the steering wheel 6 to the steering gear 8 through the steering column composed of one or a plurality of steering shafts 2, whereby the tie rod 9. It is made to convert into the reciprocating motion. If the steering shaft 2 cannot be arranged in a straight line in consideration of the vehicle-mounted space, etc., one or more shaft couplings 1 are arranged between the steering shafts 2 and the steering gear 8 can be rotated accurately even when the steering shaft 2 is bent. It is possible to transmit exercise. A fixed type constant velocity universal joint is used for the shaft joint 1. A symbol α in FIG. 13B represents a bending angle of the joint, and a large angle at which the bending angle α exceeds 30 ° can be set.

  Next, the fixed type constant velocity universal joint will be described. The fixed type constant velocity universal joint 1 of this embodiment is a Rzeppa type joint (BJ). As shown in FIG. 1, an outer ring 10 as an outer member, an inner ring 20 and a shaft 2 constituting the inner member, and torque are supplied. The transmitting ball 30 and the retainer 40 that supports the ball 30 are constituted as main components. The outer ring 10 is connected to the input shaft or the output shaft, and the inner ring 20 is connected to the output shaft or the input shaft. In this embodiment, the inner member is configured by coupling the shaft 2 to the inner circumference of the inner ring 20 via torque transmission means such as serrations and splines.

  The outer ring 10 has a cup shape opened at one end, and a track groove 14 extending in the axial direction is formed at a circumferentially equidistant position of the spherical inner surface 12. Further, the inner ring 20 is formed with a track groove 24 extending in the axial direction at equal circumferential positions on the spherical outer surface 22. The track groove 14 of the outer ring 10 and the track groove 24 of the inner ring 20 form a pair of ball tracks extending in a wedge shape from one to the other in the axial direction, and one ball 30 is incorporated in each ball track. The cage 40 is slidably interposed between the spherical inner surface 12 of the outer ring 10 and the spherical outer surface 22 of the inner ring 20, and each ball 30 is accommodated in a pocket 46 of the cage 40 and is held at equal intervals in the circumferential direction. Has been.

The outer circumferential surface 42 of the cage 40 is in spherical contact with the spherical inner surface 12 of the outer ring 10, and the inner circumferential surface 44 of the cage 40 is spherically fitted to the spherical outer surface 22 of the inner ring 20. The center of the spherical inner surface 12 of the outer ring 10 and the center of the spherical outer surface 22 of the inner ring 20 coincide with the joint center O. In contrast, the center O ₁ of the track groove 14 of the outer ring 10 and the center O ₂ of the track groove 24 of the inner ring 20 are offset by an equal distance in the opposite directions in the axial direction. For this reason, the ball track formed by the pair of track grooves 14 and 24 has a wedge shape that expands from the back side of the outer ring 10 toward the opening side.

  In this fixed type constant velocity universal joint, as shown in FIG. 2, the ball 30 guided by the cage 40 always has an operating angle θ regardless of the bending angle, that is, the operating angle θ between the outer ring 10 and the inner ring 20. It is maintained in a plane perpendicular to the bisector, ensuring constant velocity of the joint.

  In this fixed type constant velocity universal joint, a plunger unit 50 is attached to the shaft end of the shaft 2 as shown in FIG. As shown in FIG. 3, the plunger unit 50 includes a ball 53 as a pressing member having a pressing portion 52 at the tip, a compression coil spring 54 as an elastic member, and a case as a housing member that houses the ball 53 and the compression coil spring 54. 55 is an assembly body. The compression coil spring 54 serves as a generation source of an elastic force that presses the ball 53 toward the back side of the outer ring 10 (the ball protruding direction).

  The structure for attaching the plunger unit 50 to the shaft 2 is as follows. FIG. 5 shows a state before the plunger unit 50 is attached to the shaft 2, and FIG. 6 shows a state after the plunger unit 50 is attached to the shaft 2.

  As shown in the figure, the plunger unit 50 is fixed by press-fitting or adhering the case 55 to a recess 2 a formed at the shaft end of the shaft 2. When the fixing of the case 55 is completed, the flange 55b of the case 55 is engaged with the shaft end surface 2b of the shaft 2, whereby the plunger unit 50 is positioned with reference to the shaft end surface 2b. That is, even if the depth varies due to processing tolerances of the recessed portion 2 a of the shaft 5, the depth of the recessed portion 2 a is made larger than the axial length of the case 55 of the plunger unit 50, and the flange 55 b is connected to the shaft 2. The plunger unit 50 can be positioned because it is engaged with the shaft end surface 2b.

  As shown in FIGS. 7 (a) and 7 (b), the case 55 of the plunger 50 has a bottomed cylindrical shape, and a locking portion 55a that protrudes toward the inner diameter side is provided at the opening edge of the plunger 50, whereby the locking portion 55a. The inner diameter φd of the ball 53 becomes smaller than the outer diameter φD of the ball 53, so that the removal of the ball 53 can be prevented. Thus, an assembly body in which the ball 53, the compression coil spring 54, and the case 55 are unitized is formed. Here, as a means for providing a locking portion for preventing the ball 53 from being pulled out, as shown in FIGS. 7A and 7B, the opening edge of the case 55 is arranged on the inner diameter side over the entire circumference. In addition to forming the locking portion 55a by crimping, the following various structures are applicable.

  First, as shown in FIGS. 8 (a) and 8 (b), a part of the flange 55b of the case 55 (two places facing each other in the circumferential direction 180 °) is cut out to form a tongue piece facing the outer diameter side. The locking portion 55c is formed by bending the piece to the inner diameter side. Note that the number of the raised portions may be two or more. In the structure shown in FIGS. 9A and 9B, a part of the flange 55b (three circumferentially equidistant portions) extends radially outward, the extended part is folded back to the inner diameter side, and the tip is The locking portion 55d is formed by crimping.

  Further, the structure shown in FIGS. 10A and 10B is formed by cutting a part of the flange 55b (three places equally spaced in the circumferential direction) to form a tongue that faces the inner diameter side. The locking portion 55e is formed by inclining the raising surface by β ° with respect to the radial direction and by inclining and raising the end surface by β ° with respect to the axial direction. The locking portion 55e functions as a wedge by inclining the tongue piece by β ° as described above. Note that slits 55f are formed at a plurality of locations in the circumferential direction of the flange 55b. The slit 55f is for slightly bending the flange 55b when the ball 53 is inserted into the case 55.

  Further, in the structure shown in FIGS. 11 (a) and 11 (b), an annular member 61 separate from the case 55 is superposed on the flange 55b, and a part of the flange 55b (two places facing each other in the circumferential direction 180 °) is cut. An annular member is formed by forming a tongue piece 55h that rises and faces toward the outer diameter side, inserts the tongue piece 55h into a hole (not shown) formed in a corresponding portion of the annular member 61, and crimps the tip thereof. 61 is fixed to the flange 55b. The inner diameter side of the annular member 61 is curved toward the outer side in the axial direction, and by making the inner diameter φd of the curved end portion smaller than the outer diameter φD of the ball 53, the curved end portion becomes the locking portion 55g. Become. The structure shown in FIGS. 12 (a) and 12 (b) uses substantially the same annular member 61 described in the structure shown in FIGS. 11 (a) and 11 (b), and the fixing means for the flange 55b is the case described above. In contrast, as shown by the dotted line m in FIG. 5A, the annular member 61 is fixed to the flange 55b by spot welding at a plurality of locations along the circumferential direction, so that the curve positioned at the inner diameter of the annular member 61 is obtained. The end portion becomes the locking portion 55g.

  As shown in FIG. 1, a receiving member 56 is attached to the inner end of the outer ring 10 of the cage 40. The receiving member 56 has a lid shape covering the end opening of the cage 40, and includes a spherical portion 56a having a partially spherical shape and an attachment portion 56b formed in an annular shape on the outer periphery thereof as shown in FIG. . The inner surface (the surface facing the shaft 2) of the spherical portion 56 a is a concave spherical surface, and this concave spherical surface functions as a receiving portion 58 that receives the pressing force from the pressing portion 52. The attachment portion 56b is fixed to the end portion of the cage 40 by appropriate means such as press fitting or welding.

  When the shaft 2 of this constant velocity universal joint takes an operating angle, a concave spherical surface is formed as shown in FIG. 4 in order to smoothly slide between the pressing portion 52 of the plunger unit 50 and the receiving portion 58 of the receiving member 56. The inner diameter dimension Ro of the receiving part 58 is larger than the outer diameter dimension r (see FIG. 3) of the ball 53 having the pressing part 52 (Ro> r). Further, in order to prevent interference between the receiving member 56 and the inner ring 20 when the operating angle θ (see FIG. 2) is taken, the inner diameter dimension Ro of the receiving part 58 is larger than the outer diameter dimension Ri of the spherical outer surface 22 of the inner ring 20. (Ro> Ri).

  In the above configuration, when the serration shaft portion of the shaft 2 and the inner ring 20 are serration-coupled and the retaining ring 4 is attached and the two are completely coupled (see FIGS. 1, 3 and 4), the plunger unit 50 The pressing portion 52 and the receiving portion 58 of the receiving member 56 come into contact with each other, the ball 53 is retracted, and the compression coil spring 54 is compressed. Here, as described above, since the plunger unit 50 is positioned with reference to the shaft end surface 2b of the shaft 2, the mounting state of the pressing portion 52 is stabilized and the contact state between the pressing portion 52 and the receiving portion 58 is changed. The pressure can be always constant, and the pressing force from the pressing portion 52 can be reliably applied to the portion 58.

  Due to the pressing force from the pressing portion 52, the inner ring 20 integrated with the shaft 2 is axially displaced toward the opening side of the outer ring 10 by an elastic force, and the ball 30 disposed in the track grooves 14 and 24 due to this displacement. Since the clearances of the track grooves 14 and 24 are reduced, the axial clearances of the track grooves 14 and 24 are filled and rotation backlash is reliably prevented.

1 is a cross-sectional view showing an overall configuration of a constant velocity universal joint for steering in an embodiment of a fixed type constant velocity universal joint according to the present invention. FIG. 2 is a cross-sectional view showing a state where two axes take an operating angle in the constant velocity universal joint of FIG. 1. It is a principal part enlarged view of FIG. It is a principal part enlarged view of FIG. It is an enlarged view which shows the state before attaching a plunger unit to a shaft. It is an enlarged view which shows the state after attaching a plunger unit to a shaft. It is for demonstrating the ball | bowl pull-out prevention means in a plunger unit, (a) is a front view, (b) is sectional drawing which follows the AA line of (a). It is for demonstrating the other ball pull-out prevention means in a plunger unit, (a) is a front view, (b) is sectional drawing which follows the BOB line of (a). It is for demonstrating the other ball pull-out prevention means in a plunger unit, (a) is a front view, (b) is sectional drawing which follows the C-O-C line of (a). It is for demonstrating the other ball | bowl extraction prevention means in a plunger unit, (a) is a front view, (b) is sectional drawing which follows the D-O-D line of (a). It is for demonstrating the other ball pull-out prevention means in a plunger unit, (a) is a front view, (b) is sectional drawing which follows the EE line of (a). It is for demonstrating the other ball pull-out prevention means in a plunger unit, (a) is a front view, (b) is sectional drawing which follows the FF line of (a). (A) is a plan view of the steering device, (B) is a side view of the steering device, and (C) is a perspective view of the steering device.

Explanation of symbols

2 Inner member (shaft)
10 Outer member (outer ring)
12 spherical inner surface 14 track groove 20 inner member (inner ring)
22 spherical outer surface 24 track groove 30 ball 40 cage 50 plunger unit 52 pressing portion 53 pressing member (ball)
54 Elastic member (compression coil spring)
55 Housing member (case)
55a Locking portion 55b Flange 56 Receiving member 58 Receiving portion

Claims (6)

An outer member having a spherical inner surface in which a plurality of track grooves are formed, an inner member having a spherical outer surface in which a plurality of track grooves are formed, a track groove in the outer member, and a track groove in the inner member. An elastic pusher includes a ball arranged on a wedge-shaped ball track formed in cooperation, a cage arranged between the spherical inner surface of the outer member and the spherical outer surface of the inner member, and holding the ball. In the fixed type constant velocity universal joint having a preload means in which a pressing portion for applying pressure in the axial direction is provided on the inner member side and a receiving portion for receiving the pressing force from the pressing portion is provided on the cage side. By assembling the plunger unit formed at the tip to the recessed portion formed on the inner member side and engaging the flange of the plunger unit with the end surface on the inner member side, the end surface on the inner member side is Positioning and fixing as a reference Fixed type constant velocity universal joint, characterized in that.   The plunger unit includes a pressing member having a pressing portion at a tip thereof, an elastic member that elastically biases the pressing member toward the receiving portion, and a bottomed cylindrical housing member that houses the pressing member and the elastic member. The fixed type constant velocity universal joint according to claim 1, wherein the assembly body is provided with an engaging portion having an inner diameter smaller than an outer diameter of the pressing member at an opening end of the housing member.   The fixed type constant velocity universal joint according to claim 2, wherein the locking portion is formed by caulking the opening end of the housing member.   The fixed type constant velocity universal joint according to claim 3, wherein the locking portion is formed by caulking a part of the opening end of the housing member along the circumferential direction.   The fixed type constant velocity universal joint according to any one of claims 2 to 4, wherein the locking portion is formed by joining a member different from the housing member to the opening end of the housing member.   The constant velocity universal joint as described in any one of Claims 1-5 incorporated in the steering device of the motor vehicle.