JP2012122511A - Shaft for constant velocity universal joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shaft for a constant velocity universal joint whose rigid impression is not impaired while absorbing torsional vibration (vibration in the rotation direction).SOLUTION: In the shaft for the constant velocity universal joint, the constant velocity universal joint is connected to an output side end 1a and an input side end 1b, respectively, and a damping mechanism 4 for suppressing torque variation from the input side end 1b by resistance in the rotation direction is provided at a center part of the shaft for the constant velocity universal joint between the output side end 1a and the input side end 1b. The damping mechanism 4 comprises an intermediate shaft 1c connecting the output side end 1a and the input side end 1b, and an tubular outer member 2 to be outwardly fitted to the intermediate shaft 1c. The intermediate shaft 1c and the outer member 2 are displaced relatively in the rotation direction at a suppression part.

Description

  The present invention relates to a constant velocity universal joint shaft that can suppress torsional vibration generated in a drive system.

  Power transmission means to drive wheels for automobiles is smoothly transmitted without torque fluctuation by a fixed type constant velocity universal joint and a sliding type constant velocity universal joint connected by a half shaft. As described above, in the drive system including the constant velocity universal joint, the vibration from the engine is mainly absorbed by the sliding type constant velocity universal joint so that the vibration is not transmitted to the vehicle body as an unpleasant vibration.

  However, the vibration absorption direction in the sliding type constant velocity universal joint is all in the sliding direction (axial direction) and cannot absorb the displacement in the twisting direction (rotating direction). That is, it is not possible to absorb torque fluctuations accompanying rotation fluctuations from the engine side, so-called torsional vibrations.

  For this reason, conventionally, the outer joint member (outer ring) has a two-layer structure of an outer cylinder part and an inner cylinder part, and relative movement in the axial direction and around the axis center between the outer cylinder part and the inner cylinder part. There is a constant velocity universal joint that interposes a guide device that allows relative rotation (Patent Document 1). The constant velocity universal joint includes a suppression device (made of a rubber material) that suppresses relative movement in the axial direction between the outer cylinder portion and the inner cylinder portion and relative rotation around the axis.

  As shown in FIGS. 13 and 14, the guide device 102 described in Patent Document 1 includes a sliding body 106 disposed between an outer cylinder portion 76 and an inner cylinder portion 82. An axial groove 108 is formed between the sliding body 106 and a circumferential groove 110 is formed between the inner cylinder portion 82 and the sliding body 106, and the rolling elements 112, 114 are fitted into the grooves 108, 110. It is to be combined.

  Further, as shown in FIG. 14, a relative restraining device having a first spring 96 and a second spring 98 interposed between the sliding plates 100, 100 is disposed in the vicinity of the sliding body 106 in the guide device 102. ing. This relative suppression device suppresses relative rotation of the outer cylinder portion 76 and the inner cylinder portion 82 around the axis.

  In the constant velocity universal joint described in Patent Document 1, the configuration as described above, “the torsional rigidity of the constant velocity universal joint for a vehicle that is a part of the drive system is reduced and the resonance frequency of the drive system is reduced. The torsional resonance of the drive shaft is suppressed, and the lockup rotation speed of the lockup clutch can be reduced while suppressing the generation of noise such as a lockup booming noise. Furthermore, “a damping element that generates a relative movement resistance according to the relative rotational speed of the outer cylinder portion and the inner cylinder portion around the axis center is provided, and the torsional vibration generated in the drive system is absorbed by the damping element. Therefore, the vibration generated in the drive system can be sufficiently suppressed. "

JP 2010-144663 A

  However, in Patent Document 1, the amount of relative displacement with respect to the rotation direction of the outer ring is regulated by the operating range of the rolling element 114, and the torsional rigidity during this period is determined by the spring force of the relative restraining device. You will tune it to get it.

  Further, since the rubber element (relative rotation suppressing device) is provided in the circumferential gap between the outer cylinder portion 76 and the inner cylinder portion 82, the torsional vibration generated in the drive system is always transmitted through the rubber element. It propagates between the outer cylinder part 76 and the inner cylinder part 82. For this reason, the torsional vibration generated in the drive system can be suppressed.

  However, since the torsional vibration absorbing structure described in Patent Document 1 is a structure that is largely twisted in the rotational direction in the low torque region, the displacement in the rotational direction becomes large in a situation where the torque input changes between positive and negative. For this reason, in a traveling state in which acceleration / deceleration is repeated (load torque is switched between positive and negative), the feeling of rigidity (= direct feeling) is impaired.

  An object of the present invention is to propose a shaft for a constant velocity universal joint that absorbs torsional vibration (vibration in the rotational direction) and does not impair rigidity.

  In the constant velocity universal joint shaft of the present invention, the constant velocity universal joint is connected to the output side end and the input side end, respectively, and the constant velocity universal joint shaft center between the output side end and the input side end is provided. The constant velocity universal joint shaft is provided with a damping mechanism (that is, a damping mechanism using a torsional displacement of the shaft) that suppresses torque fluctuation from the input side end portion by resistance in the rotational direction. Is composed of an intermediate shaft that connects the output side end and the input side end, and a cylindrical outer member that is externally fitted to the intermediate shaft, and the intermediate shaft and the outer member It is relatively displaced in the rotation direction.

  By providing the damping mechanism, the constant velocity universal joint shaft according to the present invention can suppress the rotational fluctuation accompanying the fluctuation of the input torque, that is, can absorb the vibration in the torsional direction.

  The outer member is coupled to the intermediate shaft on the torque input side or the torque output side, and the fitting portion with the intermediate shaft on the torque output side or the torque input side not coupled to the intermediate shaft serves as the suppression portion. It can be displaced relative to the intermediate shaft.

  This is a solid shaft in which an output side end, an intermediate shaft, and an input side end are integrally formed. Further, it is preferable that the intermediate shaft and the outer member are fitted with a tightening margin at the restrained portion.

  A lubricant may be interposed between the intermediate shaft and the outer member at the fitting portion serving as the suppression portion where the intermediate shaft and the outer member are relatively displaced. By interposing the lubricant in this way, the relative displacement at the suppression site is smoothly performed.

  A lubricant reservoir for storing the lubricant can be provided at the fitting site. Even if the concave portion disposed at a predetermined pitch along the circumferential direction is formed on the inner diameter surface of the outer member in the fitting portion to constitute the lubricant reservoir, the intermediate shaft in the fitting portion Even if the lubricant reservoir is formed by forming recesses arranged at a predetermined pitch along the circumferential direction on the outer diameter surface, the recesses are formed on the outer diameter surface near the boot fixing portion of the intermediate shaft. It may be formed to constitute the lubricant reservoir.

  By providing the lubricant reservoir in this way, the lubricant can be stably interposed at the suppression portion, the frictional resistance at the suppression portion can be reduced, and the relative displacement can be performed smoothly.

  It is good also considering the circumferential direction edge part in the recessed part for comprising the said lubricant reservoir part as a round part. By providing the rounded portion in this manner, it is possible to prevent the circumferential edge portion of the concave portion from being caught at the time of relative displacement at the suppression portion.

  A slit extending in the axial direction along the circumferential direction may be provided on the outer member at the fitting portion, and the diameter of the remaining portion between the slits adjacent in the circumferential direction may be reduced in the inner diameter direction. By providing the slit in this way, it is possible to easily perform tightening fitting at the fitting portion.

  Even when the remaining portion is reduced in diameter toward the inner diameter direction, the fitting portion of the outer member is press-fitted into the fitting portion of the intermediate shaft, and the remaining portion is expanded in the outer diameter direction by this press-fitting. Good. With this configuration, it is possible to stably generate a resistance at the time of rotational displacement. As a result, this resistance cancels (absorbs) fluctuation energy in the torsional direction that fluctuates instantaneously.

  The inner circumferential end of the remaining portion is preferably a rounded portion. By providing the rounded portion, it is possible to prevent the slit from being caught at the time of relative displacement at the suppression portion.

  The connection between the outer member and the intermediate shaft may be a serration connection or a connection by welding.

  Even if a sliding type constant velocity universal joint is attached to the input side end and a fixed type constant velocity universal joint is attached to the output side end, the sliding type constant velocity is attached to the input side end and the output side end. A universal joint may be attached.

  In the constant velocity universal joint shaft according to the present invention, by providing a mechanism that attenuates torque fluctuation, torsional vibration due to torque fluctuation can be absorbed. If this constant velocity universal joint shaft is used as a means for transmitting power to the drive wheels of an automobile, excellent drivability is exhibited without impairing rigidity (= direct feeling) even when the vehicle is repeatedly accelerated and decelerated. Moreover, torsional vibration can be suppressed.

  The damping mechanism can be composed of an intermediate shaft and an outer member, which can simplify the structure, and the outer member is fitted on the intermediate shaft that functions as a torque transmission shaft. Then, compactness can be achieved.

  Moreover, since the output side end, the intermediate shaft, and the input side end are integrally formed, torque transmission from the input side to the output side is stabilized.

  In the case where a lubricant is interposed between the intermediate shaft and the outer member, the relative displacement at the suppression portion can be performed smoothly, and torsional vibration can be suppressed stably. In particular, by forming the lubricant reservoir, it is possible to stabilize the interposition of the lubricant at the suppression site and to perform the relative displacement more smoothly. Further, by providing a rounded portion at the circumferential end of the recess to form the lubricant reservoir, it is possible to prevent the circumferential edge of the recess from being caught, and the relative displacement can be performed more smoothly.

  By providing a slit in the outer member, the expansion / contraction deformation at the fitting portion of the outer member can be facilitated, the tightening / fitting can be easily performed, and the assembling workability can be improved. In addition, resistance at the time of rotational displacement can be generated, and fluctuation energy in the torsional direction that fluctuates instantaneously is canceled (absorbed), so that torsional vibration can be stably suppressed. In particular, when the remaining circumferential inner diameter end is a rounded portion, the slit can be prevented from being caught and the relative displacement can be performed more smoothly.

  A sliding type constant velocity universal joint can be attached to the input side end, a fixed type constant velocity universal joint can be attached to the output side end, and it can slide to the input side end and output side end. Since a constant velocity universal joint is attached, various types of power transmission means can be configured, and the versatility is excellent.

It is a longitudinal cross-sectional view of the shaft for constant velocity universal joints of this invention. It is a principal part expansion longitudinal cross-sectional view of the said shaft for constant velocity universal joints. It is a principal part expanded horizontal sectional view of the said shaft for constant velocity universal joints. It is a principal part expanded horizontal sectional view which shows the 1st modification of the said shaft for constant velocity universal joints. It is a principal part expanded sectional view of FIG. It is a principal part expanded horizontal sectional view which shows the 2nd modification of the said shaft for constant velocity universal joints. It is a principal part expanded sectional view of the shaft for constant velocity universal joints shown in the said FIG. It is a principal part expanded horizontal sectional view which shows the 3rd modification of the said shaft for constant velocity universal joints. It is an enlarged view of the remaining part between the slits of the shaft for constant velocity universal joints shown in the said FIG. FIG. 2 is a simplified cross-sectional view of the constant velocity universal joint shaft shown in FIG. 1. It is the YY sectional view taken on the line of FIG. It is the ZZ sectional view taken on the line of FIG. It is a principal part sectional view of the conventional constant velocity universal joint for vehicles. It is a principal part expanded sectional view of the constant velocity universal joint for vehicles shown in the said FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a longitudinal sectional view of a constant velocity universal joint shaft according to the present invention. The constant velocity universal joint shaft includes a shaft main body 1 and an outer member 2 fitted on the shaft main body 1. The shaft central portion 3 is provided with a damping mechanism 4.

  The shaft main body 1 includes an output side end 1a, an input side end 1b, an intermediate shaft (main body) 1c, a small diameter portion 1d disposed between the output side end 1a and the main body 1c, and a middle portion. It has a diameter portion 1e, and a small diameter portion 1f and a medium diameter portion 1g disposed between the input side end portion 1b and the main body portion 1c.

  In this case, a fixed type constant velocity universal joint (not shown) is connected to the output side end 1a, and a sliding type constant velocity universal joint (not shown) is connected to the input side end 1b. As the fixed type constant velocity universal joint, various types such as a bar field type in which the track groove bottom has only a circular arc part and an undercut free type in which a part of the track groove bottom has a linear part are used. it can. As the sliding constant velocity universal joint, various types such as a double offset type, a tripod type, and a cross groove type can be used.

  For this reason, the output side end portion 1a has a male spline 5 formed on the outer diameter surface thereof and a circumferential groove 6 into which a retaining ring (not shown) is fitted. Similarly, the input side end portion 1b is formed with a male spline 7 on its outer diameter surface and a circumferential groove 8 into which a retaining ring (not shown) is fitted.

  The medium diameter portion 1e on the output side end 1a side constitutes a mounting portion (boot fixing portion) for a boot (not shown) for closing an opening of a fixed constant velocity universal joint (not shown). For this reason, a circumferential groove 9 is formed in the middle diameter portion 1e. Further, the intermediate diameter portion 1g on the input side end portion 1b side constitutes a mounting portion (boot fixing portion) of a boot (not shown) for closing an opening of a sliding type constant velocity universal joint (not shown). For this reason, a circumferential groove 10 is formed in the middle diameter portion 1g.

  The intermediate shaft (main body portion) 1c is connected to the central main body 12, the large diameter portion 15 connected to the intermediate diameter portion 1e on the output side end portion 1a side, and the intermediate diameter portion 1g on the input side end portion 1b side. And a large-diameter portion 16 provided continuously. The large-diameter portion 15 includes a large-diameter main body 15a and tapered portions 15b and 15c disposed on both axial sides of the large-diameter main body 15a. The large-diameter body 16a and tapered portions 16b and 16c disposed on both sides in the axial direction of the large-diameter body 16a.

  The outer member 2 includes a main body cylindrical portion 2a and a supporting small-diameter portion 2b on the input side of the main body cylindrical portion 2a. The supporting small diameter portion 2b is coupled to the large diameter portion 16 of the main body portion 1c. The bond in this case is a so-called serration bond 20. That is, as shown in FIG. 2, a male serration 20a is formed on the outer peripheral surface of the large diameter portion 16 to form a male coupling portion, and a female serration 20b is formed on the inner peripheral surface of the supporting small diameter portion 2b. The female coupling portion is configured, and the male coupling portion and the female coupling portion are fitted (engaged) to be coupled. The coupling means between the large diameter portion 16 and the supporting small diameter portion 2b is not limited to the serration coupling 20, and may be other means such as welding. In addition, the male serration in the male coupling portion in the serration coupling 20 includes a male spline, and the female serration in the female coupling portion in the serration coupling 20 includes a female spline. For this reason, the serration connection 20 includes a spline connection.

  Further, the output side end portion 11 of the outer member 2 is press-fitted into the large diameter portion 15. That is, the output side end portion 11 of the outer member 2 is fitted (externally fitted) to the large diameter portion 15 of the shaft body 1 with a predetermined tightening allowance.

  Next, a method for assembling the shaft will be described. The outer member 2 is inserted into the shaft body 1 from the input side. At this time, the output side end portion 11 of the outer member 2 is press-fitted, and the female coupling portion of the supporting small diameter portion 2 b of the outer member 2 is inserted into the male coupling portion of the large diameter portion 16 of the shaft body 1. It will be press-fitted. Thus, the constant velocity universal joint shaft shown in FIG. 1 is completed. The constant velocity universal joint shaft assembled in this way constitutes the damping mechanism 4 by the intermediate shaft 1c of the shaft body 1 and the outer member 2 fitted on the intermediate shaft 1c. That is, the large-diameter portion 15 of the intermediate shaft 1c and the output-side end portion 11 of the outer member 2 serve as a suppression portion that is relatively displaced in the rotational direction, as will be described later.

  Next, the function of the damping mechanism 4 will be described with reference to FIGS. 10 to 12. In addition, between the serration coupling 20 on the input side and the relative displacement portion on the output side (that is, the fitting portion 25 serving as a suppression portion where the intermediate shaft 1c and the outer member 2 are relatively displaced), an arbitrary predetermined dimension A is provided. Set to On the input side, the intermediate shaft 1c and the outer member 2 are coupled by the serration coupling 20, so that when a torque load is applied on the input side as shown in FIG. 10, as shown in FIG. The outer member 2 is synchronized with the torsional displacement (θt) of the intermediate shaft 1c. In FIG. 11, P1 shows the phase of the intermediate shaft 1c and the outer member 2 at the time of torque load. On the other hand, since they are not coupled on the output side, a phase difference (θt) is generated between the intermediate shaft 1c and the outer member 2 as shown in FIG. However, on the output side, the outer member 2 is fitted to the intermediate shaft 1c with a predetermined tightening allowance, so that the fluctuation energy in the torsional direction that fluctuates instantaneously is canceled by the generated frictional force (resistance force) ( Absorbed). For this reason, torsional vibration can be suppressed (damped). In FIG. 12, P2 indicates the phase of the intermediate shaft 1c during torque load, and P3 indicates the phase of the outer member 2 during torque load.

  Thus, in the present invention, by providing the damping mechanism 4 for suppressing torque fluctuation, torsional vibration due to torque fluctuation can be absorbed. For this reason, if this constant velocity universal joint shaft is used as a power transmission means to drive wheels in an automobile, excellent drivability without impairing rigidity (= direct feeling) in a running state where acceleration and deceleration are repeated Is demonstrated.

  The damping mechanism 4 can be configured by the intermediate shaft 1c and the outer member 2, and the configuration can be simplified. Further, the outer member 2 is in contrast to the intermediate shaft 1c that functions as a torque transmission shaft. The external fitting can be made compact.

  In addition, since the output side end 1a, the intermediate shaft 1c, and the input side end 1b are integrally formed, torque transmission from the input side to the output side is stabilized.

Incidentally, a lubricant may be interposed between the outer diameter surface of the large diameter portion 15 of the intermediate shaft 1 c and the inner diameter surface of the output side end portion 11 of the outer member 2 in the fitting portion 25. Thus, the relative displacement in the suppression part can be performed smoothly, and torsional vibration can be suppressed stably.
As the lubricant in this case, grease or the like can be used.

  As shown in FIG. 4, the lubricant reservoir 30 may be provided at a part in the circumferential direction between the intermediate shaft and the outer member in the fitting portion 25. In this case, the lubricant reservoir portion 30 is formed by providing the concave portions 31 on the inner diameter surface of the output side end portion 11 of the outer member 2 at a predetermined pitch (for example, 60 ° pitch) along the circumferential direction.

  As described above, by providing the lubricant reservoir 30, the intervention of the lubricant in the suppression portion is stabilized, the frictional resistance in the suppression portion can be reduced, and the relative displacement can be performed smoothly. Moreover, when providing such a recessed part 31, as shown in FIG. 5, it is preferable to make the circumferential direction edge part of the recessed part 31 into the round parts 31a and 31b. Thus, the circumferential edge of the recess 31 can be prevented from being caught and the relative displacement can be performed more smoothly.

  In the case where the lubricant reservoir 30 is provided, the lubricant reservoir 30 is configured by forming the recesses 31 disposed at a predetermined pitch along the circumferential direction on the outer diameter surface of the intermediate shaft 1 c in the fitting portion 25. You may do it. The fitting portion 25 may be a portion near the boot fixing portion 1e of the intermediate shaft 1c. In this case, the concave portion 31 is formed on the outer diameter surface of the intermediate shaft 1c in the vicinity of the boot fixing portion 1e to constitute the lubricant reservoir portion 30.

  Further, as shown in FIGS. 6 and 7, slits 33 extending in the axial direction are provided at the output side end portion 11 of the outer member 2 at a predetermined pitch (for example, 60 ° pitch) along the circumferential direction. There may be. In this case, the reduced diameter displacement in the inner diameter direction of the remaining portion 34 of the slit 33 adjacent in the circumferential direction is possible.

  Therefore, when such a slit 33 is provided, the output side end portion 11 of the outer member 2 is connected to the intermediate shaft 1c in a state where the remaining portion 34 is reduced in the inner diameter direction, as indicated by a virtual line in FIG. It is preferable to press-fit into the large-diameter portion 15 and expand the remaining portion 34 in the outer diameter direction by this press-fitting.

  By providing the slit 33, the expansion / contraction deformation at the fitting portion of the outer member 2 can be facilitated, the fastening fitting can be easily performed, and the assembling workability can be improved. In addition, resistance at the time of rotational displacement can be generated, and fluctuation energy in the torsional direction that fluctuates instantaneously is canceled (absorbed), so that torsional vibration can be stably suppressed.

  In FIG. 8, the inner circumferential ends of the remaining portion 34 are rounded portions 33a and 33b. Thus, by using the round portions 33a and 33b, the slit 33 can be prevented from being caught, and the relative displacement can be performed more smoothly.

  In the embodiment, the constant velocity universal joint shaft has a sliding type constant velocity universal joint attached to the input side end 1b and a fixed type constant velocity universal joint attached to the output side end 1a. However, as another embodiment, a sliding type constant velocity universal joint can be attached to the output side end 1a and the input side end 1b. Also, as the sliding type constant velocity universal joint in this case, various types such as a double male set type, a tripod type, or a cross groove type can be used. As described above, the constant velocity universal joint shaft of the present invention can constitute various types of power transmission means and is excellent in versatility.

  In the embodiment, the outer member 2 is coupled to the input side of the intermediate shaft 1c. However, as another embodiment, the outer member 2 may be coupled to the output side of the intermediate shaft 1c. Even in such a case, rotational fluctuation due to torque load from the input side end can be suppressed, and vibration in the torsional direction can be absorbed.

  As described above, the embodiment of the present invention has been described. However, the present invention is not limited to the above-described embodiment, and various modifications are possible. For example, as a tightening allowance, the intermediate shaft 1c and the outer member 2 are In the relative displacement portion, various changes can be made within a range in which a frictional resistance causing a phase difference is generated. In addition, a frictional resistance that causes a phase difference is also generated as a fitting range of the fitting portion 25, each volume of the lubricant reservoir 30, the number of the lubricant reservoirs 30, the size of the slits 33, the number of the slits 33, and the like. Various changes can be made within the range.

  In the above-described embodiment, the outer member 2 has a small diameter portion 2b on the input side. However, the outer member 2 may not be provided with such a small diameter portion 2b. That is, it is good also as a cylinder part of the same diameter continuous with the main body cylindrical part 2a of the input side of the outer member 2. FIG. The output side of the outer member 2 may be a small diameter portion.

  The radius of curvature of the rounded portions 31a and 31b of the recess 31 and the radius of curvature of the rounded portions 33a and 33b of the remaining portion 34 can be arbitrarily set.

1a Output side end 1c Intermediate shaft (main part)
1b Input side end portion 2 Outer member 3 Shaft center portion 4 Damping mechanism 25 Fitting portion 30 Lubricant reservoir portion 31a, 31b round portion 31 Recess 33a, 33b round portion 33 Slit 34 Remaining portion

Claims (17)

A constant velocity universal joint is connected to each of the output side end and the input side end, and torque fluctuation from the input side end occurs at the center of the constant velocity universal joint shaft between the output side end and the input side end. A constant velocity universal joint shaft provided with a damping mechanism that suppresses the rotation by resistance in the rotation direction,
The damping mechanism includes an intermediate shaft that connects the output side end and the input side end, and a cylindrical outer member that is externally fitted to the intermediate shaft. A shaft for a constant velocity universal joint, wherein the shaft is relatively displaced in a rotational direction at a restraining portion.   The outer member is coupled to the intermediate shaft on the torque input side or the torque output side, and the fitting portion with the intermediate shaft on the torque output side or the torque input side not coupled to the intermediate shaft serves as the suppression portion. The constant velocity universal joint shaft according to claim 1, wherein the constant velocity universal joint shaft is displaced relative to the intermediate shaft.   The shaft for a constant velocity universal joint according to claim 1 or 2, wherein the output side end portion, the intermediate shaft, and the input side end portion are integrally formed.   The shaft for a constant velocity universal joint according to any one of claims 1 to 3, wherein the intermediate shaft and the outer member are fitted with a tightening margin at a restrained portion thereof.   5. The lubricant according to claim 1, wherein a lubricant is interposed between the intermediate shaft and the outer member in the fitting portion serving as the suppression portion where the intermediate shaft and the outer member are relatively displaced. A shaft for a constant velocity universal joint according to claim 1.   The constant velocity universal joint shaft according to claim 5, wherein a lubricant reservoir for storing the lubricant is provided at the fitting portion. 7. The constant velocity according to claim 6, wherein the lubricant reservoir portion is configured by forming concave portions disposed at a predetermined pitch along a circumferential direction on an inner diameter surface of the outer member in the fitting portion. Universal joint shaft.   7. The constant velocity free according to claim 6, wherein the lubricant reservoir portion is formed by forming concave portions disposed at a predetermined pitch along a circumferential direction on an outer surface of the intermediate shaft at the fitting portion. Joint shaft.   The constant velocity universal joint shaft according to claim 6, wherein a concave portion is formed on an outer diameter surface of the intermediate shaft near the boot fixing portion to constitute the lubricant reservoir portion.   The shaft for a constant velocity universal joint according to any one of claims 6 to 9, wherein an edge portion in a circumferential direction of the concave portion for constituting the lubricant reservoir portion is a rounded portion.   The outer member in the fitting portion is provided with a slit extending in the axial direction along the circumferential direction, and the reduced diameter displacement in the inner diameter direction of the remaining portion between the slits adjacent in the circumferential direction is enabled. The shaft for constant velocity universal joints of any one of Claims 2-10.   In the reduced diameter state in the inner diameter direction of the remaining portion, the fitting portion of the outer member is press-fitted into the fitting portion of the intermediate shaft, and the diameter of the remaining portion is expanded in the outer diameter direction by this press-fitting. The constant velocity universal joint shaft according to claim 11.   The shaft for a constant velocity universal joint according to claim 11 or 12, wherein a circumferential inner diameter end of the remaining portion is a rounded portion.   14. The constant velocity universal joint shaft according to claim 2, wherein the coupling between the outer member and the intermediate shaft is a serration coupling.   The constant velocity universal joint shaft according to claim 2, wherein the outer member and the intermediate shaft are joined by welding.   The sliding constant velocity universal joint is attached to the input side end portion, and the fixed type constant velocity universal joint is attached to the output side end portion. Quick universal joint shaft.   The shaft for a constant velocity universal joint according to any one of claims 1 to 15, wherein a sliding type constant velocity universal joint is attached to the input side end portion and the output side end portion.

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