JP2007333154A - Constant-velocity universal joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To connect firmly an inner ring to a shaft by preventing the generation of backlash to the utmost. <P>SOLUTION: In a fitting structure between the inner ring and the shaft installed in this constant-velocity universal joint, and equipped with the inner ring 20 for transferring torque, while allowing angle displacement between itself and an outer ring, and the shaft 50 pressed into an axial hole inner diameter 26 of the inner ring 20, the axial hole inner diameter 26 of the inner ring 20 is in an uncured state, and a spline 54 as an irregular part along the circumferential direction is formed at an axial end outer diameter 52 of the shaft 50, and a cured layer n is formed at the axial end outer diameter 52, and the axial end outer diameter 52 of the shaft 50 is pressed into the axial hole inner diameter 26 of the inner ring 20, to thereby plastically couple the shaft 50 with the inner ring 20. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is used in power transmission systems of automobiles and various industrial machines. For example, fixed or sliding constant velocity universal joints incorporated in drive shafts and propeller shafts used in FF cars, 4WD cars, FR cars, etc. The present invention relates to a fitting structure between an inner joint member and a shaft.

  For example, a drive shaft of an automobile has a structure in which a sliding constant velocity universal joint is attached to one shaft end of the shaft and a fixed constant velocity universal joint is attached to the other shaft end.

  A tripod type constant velocity universal joint (TJ), which is one of the sliding type constant velocity universal joints used as a coupling for drive shafts, has three track grooves formed in the axial direction on the inner peripheral surface. The outer joint member (outer ring) having an axial roller guide surface on each side of each track groove, the inner joint member (tripod member) having three leg shafts projecting in the radial direction, and the inner joint member A rolling element (roller) rotatably accommodated between the leg shaft and the roller guide surface of the outer joint member is configured as a main member.

  In addition, a Barfield type constant velocity universal joint (BJ), which is one of fixed type constant velocity universal joints, is an outer joint member in which a plurality of track grooves are formed along the axial direction at equal intervals in the circumferential direction on the inner spherical surface ( An outer ring, an inner joint member (inner ring) formed on the outer spherical surface along the axial direction with a plurality of track grooves paired with the track grooves of the outer joint member, and a track groove of the outer joint member; The main members are a plurality of balls that transmit torque by being interposed between the track grooves of the inner joint member, and a cage that is interposed between the inner spherical surface of the outer joint member and the outer spherical surface of the inner joint member. Configured as

  A structure in which the shaft end of the shaft is press-fitted into the inner diameter of the shaft hole of the inner joint member is employed as a connection structure between the sliding constant velocity universal joint or the fixed constant velocity universal joint and the shaft. A female spline is formed as irregularities along the axial direction on the inner diameter of the shaft hole of the inner joint member, and a male spline is also formed on the outer diameter of the shaft end of the shaft.

  The inner hole of the inner joint member in which the female spline is formed and the outer diameter of the shaft end of the shaft in which the male spline is formed are hardened by, for example, induction hardening or carburizing hardening to form a hardened layer. ing. By forming this hardened layer, the strength of the inner diameter of the shaft hole of the inner joint member and the outer diameter of the shaft end of the shaft is ensured.

  The shaft is fitted to the inner joint member by press-fitting the shaft end outer diameter of the shaft into the shaft hole inner diameter of the inner joint member and meshing the male spline and the female spline. Torque can be transmitted between the shaft and the inner joint member by spline fitting (see, for example, FIG. 2 of Patent Document 1).

Further, in such a connection structure of the inner joint member and the shaft, the retaining ring having a round cross section attached to the shaft end portion of the shaft comes into contact with a locking surface provided on the inner joint member. Some have been stopped (see, for example, Patent Document 2).
JP 2003-314580 A JP-A-8-68426

  By the way, in the fitting structure of the inner joint member of the constant velocity universal joint and the shaft, a female spline that has been hardened is formed on the inner diameter of the shaft hole of the inner joint member, and the outer end diameter of the shaft is hardened. By forming the male spline, the shaft end outer diameter of the shaft is press-fitted into the shaft hole inner diameter of the inner joint member to be fitted with the spline.

  However, since the fitting structure between the inner joint member and the shaft is a concave-convex fitting between the hardened female spline and the hardened male spline, there is a problem that rattling is likely to occur. When there is play, it is difficult to reliably transmit the rotational torque, and there is a possibility that abnormal noise may be generated.

  In addition, when a retaining structure with a retaining ring is provided in the connecting structure of the inner joint member and the shaft, a process of forming a locking surface on the inner joint member is necessary, and the number of steps is increased and a retaining ring is necessary. The number of parts increases, resulting in an increase in product cost. In the process of assembling the constant velocity universal joint, a process of assembling a retaining ring is necessary, which also increases the cost of the product and requires an extra cycle time.

  Therefore, the present invention has been proposed in view of the above-mentioned problems, and the object of the present invention is to prevent the occurrence of rattling and to provide an inner joint of a constant velocity universal joint that can firmly connect the inner joint member and the shaft. The object is to provide a fitting structure between a member and a shaft.

  As technical means for achieving the above-mentioned object, the present invention provides an inner joint member that is provided in a constant velocity universal joint and transmits torque while allowing angular displacement with the outer joint member, and the inner joint member. A shaft press-fitted into the inner diameter of the shaft hole, the inner diameter of the inner joint member is uncured, and the shaft end outer diameter of the shaft is formed with a concavo-convex portion along the circumferential direction. A hardened layer is formed on the shaft, and the shaft end of the shaft is press-fitted into the inner diameter of the shaft hole of the inner joint member to plastically connect the shaft and the inner joint member. In addition, it is preferable that the shaft hole inner diameter of the inner joint member is formed by cold forging finishing.

  In the present invention, the inner diameter of the inner joint member is uncured, and an uneven portion along the circumferential direction is formed on the shaft end outer diameter of the shaft, and a hardened layer is formed on the shaft end outer diameter. When the shaft end of the shaft is press-fitted into the shaft hole inner diameter of the inner joint member, the uneven portion of the shaft end outer diameter of the shaft on which the hardened layer is formed bites into the shaft hole inner diameter of the uncured inner joint member and the inner joint member The inner diameter of the shaft hole is plastically deformed.

  In this way, the shaft and the inner joint member are integrated with each other by plastically connecting the shaft and the inner joint member, thereby eliminating backlash between the two and firmly connecting the shaft and the inner joint member. Can do.

  In the above-described configuration, it is desirable that the concavo-convex part of the shaft end outer diameter of the shaft has a concavo-convex part along the axial direction in at least a part of the axial direction. The concavo-convex portion along the axial direction may be formed in at least a part of the axial direction. That is, it may be formed at any of the tip portion, the root portion, or the intermediate portion in the axial direction, and may be formed in the entire axial direction.

  Thus, by having the uneven | corrugated | grooved part along an axial direction, it becomes a retaining prevention of the shaft end outer diameter of the shaft with respect to the axial hole internal diameter of an inner joint member, and a shaft and an inner joint member can be connected still more firmly. In addition, as an uneven | corrugated | grooved part along the axial direction mentioned above, the structure formed in sawtooth shape is suitable.

  Further, it is desirable that the concavo-convex portion of the shaft end outer diameter of the shaft has a notch formed at the tip of the shaft end outer diameter. If it does in this way, a notch edge part can be latched to the end surface of an inner joint member, and it can be set as the fall-off prevention of the shaft to the inner joint member.

  According to the present invention, the shaft hole inner diameter of the inner joint member is uncured, and an uneven portion along the circumferential direction is formed on the shaft end outer diameter of the shaft and a hardened layer is formed on the shaft end outer diameter, By pressing the shaft end of the shaft into the inner diameter of the shaft hole of the inner joint member and plastically connecting the shaft and the inner joint member, the shaft and the inner joint member are integrated to eliminate backlash between the two. The shaft and the inner joint member can be firmly connected. As a result, a constant velocity universal joint having high rigidity can be provided. Further, since it is not necessary to perform spline formation or hardening treatment on the inner diameter of the shaft hole of the inner joint member as in the prior art, the cost can be reduced.

  Embodiments of the present invention are described in detail below. In addition, although the following embodiment illustrates the case where it applies to a fixed type (Burfield type) constant velocity universal joint (BJ), other fixed type constant velocity universal joints, for example, an undercut free type constant velocity universal joint ( UJ), and also applicable to a sliding type constant velocity universal joint such as a cross groove type constant velocity universal joint (LJ) and a double offset type constant velocity universal joint (DOJ).

  FIG. 5 illustrates the overall configuration of a barfield type constant velocity universal joint. The constant velocity universal joint includes an outer ring 10 as an outer joint member, an inner ring 20 as an inner joint member disposed inside the outer ring 10, and a plurality of torque transmissions interposed between the outer ring 10 and the inner ring 20. The ball 30 and the cage 40 that is interposed between the outer ring 10 and the inner ring 20 and holds the ball 30 are configured as main members. When this fixed type constant velocity universal joint is applied to a drive shaft, the outer ring 10 is coupled to a wheel bearing device (not shown), and the inner ring 20 is coupled to a shaft 50 with a fitting structure described later, whereby the outer ring 10 is coupled. Torque is transmitted at a constant speed even when the rotation axis of the inner ring 20 forms an angle.

  The outer ring 10 includes a mouse portion 16 and a stem portion 18, and is coupled to the wheel bearing device at the stem portion 18 so that torque can be transmitted. The mouse portion 16 has a bowl shape opened at one end, and a plurality of track grooves 14 extending in the axial direction are formed on the inner spherical surface 12 at equal intervals in the circumferential direction. The track groove 14 extends to the open end of the mouse portion 16. In the inner ring 20, a plurality of track grooves 24 extending in the axial direction are formed on the outer spherical surface 22 at equal intervals in the circumferential direction. The track groove 24 is cut in the axial direction of the inner ring 20.

  The track groove 14 of the outer ring 10 and the track groove 24 of the inner ring 20 make a pair, and a ball 30 as a torque transmitting element can roll on each ball track constituted by the pair of track grooves 14, 24. It is incorporated. The ball 30 is interposed between the track groove 14 of the outer ring 10 and the track groove 24 of the inner ring 20 to transmit torque. The cage 40 is slidably interposed between the outer ring 10 and the inner ring 20, is in contact with the inner spherical surface 12 of the outer ring 10 at the outer spherical surface 42, and is in contact with the outer spherical surface 22 of the inner ring 20 at the inner spherical surface 44.

  The inner ring 20 described above is coupled to the shaft 50 so that torque can be transmitted by press-fitting the shaft end 52 of the shaft 50 into the inner diameter 26 of the shaft hole. The inner diameter 20 of the inner ring 20 is formed by cold forging, but may be formed by turning or polishing. The fitting structure between the inner ring 20 and the shaft 50 is as follows.

  FIG. 1 shows a state before the inner ring 20 and the shaft 50 are connected, and FIG. 2 shows a state after the inner ring 20 and the shaft 50 are connected. 3A is a cross section taken along line AA in FIG. 1, FIG. 3B is a cross section taken along line BB, and FIG. 4 is a cross section taken along line CC in FIG.

  In the inner ring 20, a hardened layer m (cross-hatched portion in FIG. 1) is formed by induction hardening on the track groove 24 and the outer spherical surface 22 between the track grooves 24, and the inner diameter 26 of the shaft hole is not hardened. That is, the shaft hole inner diameter 26 of the inner ring 20 is not hardened by induction hardening. In addition, about formation of the hardened layer m in the inner ring | wheel 20, it is also possible to carry out by carburizing quenching other than induction hardening. In this case, uncured in the shaft hole inner diameter 26 can be performed by a carbon-proof treatment.

  On the other hand, a hardened layer n (cross-hatched portion in FIG. 1) is formed on the outer diameter of the shaft 50 by induction hardening over the entire circumference in the axial direction. Further, a spline 54 is formed on the shaft end outer diameter 52 of the shaft 50 as an uneven portion along the circumferential direction. As a result, a spline 54 that has been hardened by induction hardening is formed on the shaft end outer diameter 52 of the shaft 50.

As described above, the shaft hole inner diameter 26 of the inner ring 20 is not hardened, and the shaft end outer diameter 52 of the shaft 50 is a state in which a hardened spline 54 is formed. Further, the inner diameter d ₁ of the shaft hole of the inner ring 20 is defined to be between the maximum diameter d ₂ and the minimum diameter d ₃ in the spline 54 of the shaft end outer diameter 52 of the shaft 50.

  As shown in FIG. 2, the shaft end outer diameter 52 of the shaft 50 is press-fitted into the shaft hole inner diameter 26 of the inner ring 20. By this press-fitting, the spline 54 of the shaft end outer diameter 52 of the shaft 50 on which the hardened layer n is formed bites into the shaft hole inner diameter 26 of the uncured inner ring 20 as shown in FIG. 26 is plastically deformed. In this way, the shaft 50 and the inner ring 20 are plastically coupled to each other so that the shaft 50 and the inner ring 20 are integrated, thereby eliminating looseness between them and firmly connecting the shaft 50 and the inner ring 20 together. it can.

  In the first embodiment described above, the structure in which only the spline 54 that is the concavo-convex portion along the circumferential direction is formed on the shaft end outer diameter 52 of the shaft 50 has been described, but the present invention is limited to this. Alternatively, the spline 54 may have a structure in which an uneven portion along the axial direction is added. Similar to the first embodiment described above, FIGS. 6, 8, 10, 12 and 15 show the state before the inner ring 20 and the shaft 50 are connected, FIGS. 7, 9, 11, 13, and 15. FIG. Reference numeral 16 denotes a state after the inner ring 20 and the shaft 50 are connected to each other. The same or corresponding parts as those in the first embodiment shown in FIG. 1 and FIG.

  In the second embodiment shown in FIG. 6, the sawtooth 56 is formed as an uneven portion along the axial direction on the spline 54 of the shaft end outer diameter 52 of the shaft 50. That is, the convex tooth portion constituting the spline 54 is formed in a sawtooth shape along the axial direction.

  As shown in FIG. 7, when the shaft end outer diameter 52 of the shaft 50 is press-fitted into the shaft hole inner diameter 26 of the inner ring 20, the spline 54 of the shaft end outer diameter 52 of the shaft 50 on which the hardened layer n is formed becomes uncured. The inner ring 20 bites into the shaft hole inner diameter 26 and plastically deforms the inner ring 20 shaft hole inner diameter 26 along the circumferential direction, and the saw-tooth 56 bites into the uncured inner ring 20 shaft hole inner diameter 26. The inner diameter 26 of the inner ring 20 is also plastically deformed along the axial direction.

  Since the saw-tooth 56 along the axial direction is formed in this way, it functions as a retaining stopper for the shaft 50 with respect to the inner ring 20, so that a retaining ring as a conventional retaining structure is not required, and the number of parts can be reduced. As a result, it is not necessary to process the inner ring 20, so that the cost is not increased. The shaft 50 and the inner ring 20 can be more firmly connected with the retaining by the saw blade 56.

  The portion where the convex tooth portion of the spline 54 is formed in a sawtooth shape along the axial direction is formed over the entire axial direction of the spline 54 as in the second embodiment, for example, FIG. 8 and FIG. 9 may be only the root portion of the spline 54 as in the third embodiment, and in addition to the tip portion of the spline 54 as in the fourth embodiment shown in FIGS. As in the fifth embodiment shown in FIG. 13, only an intermediate portion between the tip portion and the root portion may be used.

  Further, these saw teeth 56 are not necessarily provided on all of the many convex tooth portions along the circumferential direction in the spline 54, but are provided on a part of the many convex tooth portions along the circumferential direction. It may be. For example, in the example shown in FIGS. 14 (a) and 14 (b), four convex teeth in the spline 54 are provided at saw teeth 56 (four locations in FIG. 14 (b)).

  Moreover, you may make it form the notch 58 in the front-end | tip part of the spline 54 like 6th embodiment shown in FIG. If the notch 58 is formed in this way, when the shaft end outer diameter 52 of the shaft 50 is press-fitted into the shaft hole inner diameter 26 of the inner ring 20, the end of the notch 58 becomes the end surface of the inner ring 20 as shown in FIG. 16. The shaft 50 is prevented from coming off from the inner ring 20 and the fitting structure between the inner ring 20 and the shaft 50 is further strengthened. This is the case where the saw blade 56 is formed in a portion including the tip portion of the spline 54 as in the second embodiment (see FIGS. 6 and 7) and the fourth embodiment (see FIGS. 10 and 11). A similar effect can be obtained.

  In each of the above embodiments, the case where the present invention is applied to a constant velocity universal joint of a drive shaft has been described. However, the present invention is not limited to this, and can also be applied to a constant velocity universal joint of a propeller shaft.

  The present invention is not limited to the above-described embodiments, and can of course be implemented in various forms without departing from the gist of the present invention. It includes the equivalent meanings recited in the claims and the equivalents recited in the claims, and all modifications within the scope.

It is sectional drawing which shows the state before connecting an inner ring | wheel and a shaft in 1st embodiment of this invention. In 1st embodiment of this invention, it is sectional drawing which shows the state after connecting an inner ring | wheel and a shaft. (A) is sectional drawing which follows the AA line of FIG. 1, (b) is sectional drawing which follows the BB line of FIG. It is sectional drawing which follows the CC line of FIG. It is sectional drawing which shows the whole structure of a fixed type constant velocity universal joint (Burfield type constant velocity universal joint). It is sectional drawing which shows the state before connecting an inner ring | wheel and a shaft in 2nd embodiment of this invention. It is sectional drawing which shows the state after connecting an inner ring | wheel and a shaft in 2nd embodiment of this invention. In 3rd embodiment of this invention, it is sectional drawing which shows the state before connecting an inner ring | wheel and a shaft. In 3rd embodiment of this invention, it is sectional drawing which shows the state after connecting an inner ring | wheel and a shaft. It is sectional drawing which shows the state before connecting an inner ring | wheel and a shaft in 4th embodiment of this invention. It is sectional drawing which shows the state after connecting an inner ring | wheel and a shaft in 4th embodiment of this invention. It is sectional drawing which shows the state before connecting an inner ring | wheel and a shaft in 5th embodiment of this invention. It is sectional drawing which shows the state after connecting an inner ring | wheel and a shaft in 5th embodiment of this invention. FIG. 4 is a modification example in which saw teeth are provided on a spline having a shaft end outer diameter of a shaft, (a) is a partial front view showing the shaft end outer diameter of the shaft, and (b) is a cross-sectional view taken along the line D-D of (a). . It is sectional drawing which shows the state before connecting an inner ring | wheel and a shaft in 6th embodiment of this invention. It is sectional drawing which shows the state after connecting an inner ring | wheel and a shaft in 6th embodiment of this invention.

Explanation of symbols

10 Outer joint member (outer ring)
20 Inner joint member (inner ring)
26 Shaft Bore Inner Diameter 50 Shaft 52 Shaft End Outer Diameter 54 Irregularities (Splines) along the Circumferential Direction
56 Concavity and convexity along the axial direction (sawtooth)
58 Notch m, n Hardened layer

Claims (6)

  An inner joint member that is mounted on a constant velocity universal joint and transmits torque while allowing angular displacement with the outer joint member; and a shaft that is press-fitted into the inner diameter of the shaft hole of the inner joint member. The shaft hole inner diameter of the shaft is uncured, and an uneven portion along the circumferential direction is formed on the shaft end outer diameter of the shaft and a hardened layer is formed on the shaft end outer diameter, and the shaft end of the shaft is connected to the inner joint. A fitting structure between an inner joint member of a constant velocity universal joint and a shaft, wherein the shaft and the inner joint member are plastically coupled by press-fitting into the inner diameter of the shaft hole of the member.   The inner joint member of the constant velocity universal joint according to claim 1, wherein the inner diameter of the shaft hole of the inner joint member is formed by cold forging finishing.   The inner joint member of the constant velocity universal joint according to claim 1 or 2, wherein the shaft hole inner diameter dimension of the inner joint member is defined between the maximum diameter and the minimum diameter of the uneven portion of the shaft end outer diameter of the shaft. Construction.   The inner joint member and the shaft of the constant velocity universal joint according to any one of claims 1 to 3, wherein the uneven portion of the shaft end outer diameter of the shaft has an uneven portion along the axial direction in at least a part of the axial direction. Fitting structure.   5. The fitting structure between the inner joint member of the constant velocity universal joint and the shaft according to claim 4, wherein the uneven portion along the axial direction of the shaft is formed in a sawtooth shape.   The uneven portion along the axial direction of the shaft has a notch formed at the tip of the outer diameter of the shaft end, and the inner joint member of the constant velocity universal joint according to any one of claims 1 to 3 and the shaft. Mating structure.

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