JP2008207575A - Vehicular propulsion shaft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicular propulsion shaft having an axially expandable slide structure which is capable of reducing play in the slide structure according to the traveling condition of a vehicle. <P>SOLUTION: When a propeller shaft 24 is expanded, a male spline tooth 50 of a first shaft 46 is engaged with a female spline tooth 56 of a second shaft 48 only in a part thereof. Since an inner circumferential surface of an annular projecting part 60 provided on a cylindrical part 54 presses an outer circumferential surface of an annular projecting part 64 provided on the second shaft 48, a cylindrical shaft end of the second shaft 48 is deformed inward of the radial direction. Thus, a space in the radial direction between the male spline tooth 50 and the female spline tooth 56 is reduced to reduce a play in the radial direction and a play in an oblique direction. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vehicle propulsion shaft for transmitting rotation from a drive source such as an engine to wheels and the like, and more particularly to a slide structure that makes the vehicle propulsion shaft extendable.

  In general, in a front engine / rear drive type (FR type) vehicle, the rotation of the engine is shifted by a transmission and then transmitted to the left and right rear wheels via a propeller shaft and a differential gear device that function as a propulsion shaft. Is done. This propeller shaft is installed between a transmission fixed to the body and a differential gear device that moves up and down relative to the body, and changes in angle according to the running state of the vehicle, such as road surface unevenness and vehicle acceleration / deceleration It is required to be able to expand and contract in the axial direction so that In general, the propeller shaft expandable structure allows a pair of shaft members to be splined to enable expansion and contraction in the axial direction and to prevent relative rotation of the shaft members. In a propulsion shaft such as a propeller shaft that allows expansion and contraction, if there is a large radial clearance (clearance) between the spline fitting portions, the radial play due to the clearance and the shaft of the mutual shaft member There is a tendency for looseness due to misalignment, or so-called rattle, to occur, and there is a possibility that vibration and noise due to these looseness will increase. With respect to this problem, in Patent Document 1, a slit is formed in the female-side spline, and the female-side spline is compressed from the outside with an annular fastening member made of an elastic body, whereby the radial play of the spline fitting portion and The amount of backlash is always reduced.

Japanese Utility Model Publication No. 63-17862

  By the way, in the region where the male side spline and the female side spline are completely fitted, the rattle is relatively small, but the male side spline and the female side spline are not sufficiently fitted, that is, the propulsion shaft is extended. In the region where only a part of each spline is fitted, the so-called rattle where the axial center of the first axis and the axial center of the second axis that should originally be in a straight line intersect increases. With respect to such a problem, the radial play and backlash can be reduced by eliminating the radial gap of the spline fitting portion as in Patent Document 1. However, in the spline coupling structure of Patent Document 1, since the female-side spline is always compressed regardless of the spline fitting state, the surface pressure applied to the tooth surface and the large diameter of the spline fitting even in a small backlash region. There is a possibility that wear is promoted by this surface pressure, and the durability against the seizure of the spline may be reduced accordingly.

  The present invention has been made in the background of the above circumstances, and an object of the present invention is to provide a vehicle propulsion shaft having an axially expandable / contractible slide structure in accordance with the running state of the vehicle. An object of the present invention is to provide a vehicle propulsion shaft that reduces the amount of play.

  In order to achieve the above object, the gist of the invention according to claim 1 is that (a) a first shaft having a male-side fitting portion formed on the outer peripheral surface of the shaft end, and the shaft end is a cylinder. And a second shaft having a female-side fitting portion formed on the inner peripheral surface thereof, wherein the male-side fitting portion of the first shaft and the female-side fitting portion of the second shaft are In the vehicle propulsion shaft that is capable of extending and contracting in the axial direction and being relatively non-rotatable by being fitted to each other, (b) on the outer peripheral side of the shaft end of the first shaft, with respect to the first shaft A cylindrical portion that is not relatively movable in the axial direction is disposed on the same axis, and (c) an annular shape that protrudes radially inward from the inner peripheral surface of the cylindrical portion in the vicinity of the opening end of the cylindrical portion. (D) An annular second protrusion projecting radially outward from the outer peripheral surface is provided in the vicinity of the opening end of the second shaft formed in the cylindrical shape. (E) the inner diameter of the first protrusion is smaller than the outer diameter of the second protrusion, and (f) the side of the first protrusion opposite to the opening side of the cylindrical portion. An inclined surface is formed on at least one of the end surface of the second protrusion and the end surface of the second protrusion opposite to the opening side of the second shaft.

  According to a second aspect of the present invention, there is provided a vehicle propulsion shaft according to the first aspect, wherein a plurality of the shaft ends of the second shaft formed in the cylindrical shape are notched in the axial direction. A number of slits are formed.

  According to a third aspect of the present invention, there is provided the vehicle propulsion shaft according to the first or second aspect, wherein the end surface of the first protrusion opposite to the opening side of the cylindrical portion, and the second An inclined surface having the same gradient is formed on both end surfaces of the protrusion opposite to the opening side of the second axis.

  According to a fourth aspect of the present invention, there is provided the vehicle propulsion shaft according to any one of the first to third aspects, wherein the male side fitting portion and the female side fitting portion are respectively provided with an outer peripheral spline tooth and an inner side spline tooth. It is characterized by being provided with circumferential spline teeth and being spline-fitted with each other.

  According to a fifth aspect of the present invention, in the vehicle propulsion shaft according to the fourth aspect, the tooth tip surface of the outer peripheral spline teeth and the tooth bottom surface of the inner peripheral spline teeth are brought into sliding contact with each other. It is characterized by.

  According to a sixth aspect of the present invention, there is provided a vehicle propulsion shaft according to any one of the first to fifth aspects, wherein the opening end of the cylindrical portion is in sliding contact with the outer peripheral surface of the second shaft. A member is provided.

  According to the vehicle propulsion shaft of the first aspect of the present invention, when the vehicle propulsion shaft is extended, each of the male-side fitting portion of the first shaft and the female-side fitting portion of the second shaft is provided. Only the portion is fitted, but the inner peripheral surface of the first protrusion provided on the cylindrical portion presses the outer peripheral surface of the second protrusion provided on the second shaft. The shaft end of the second shaft formed in the cylindrical shape is deformed radially inward. Thereby, the radial gap between the male side fitting part and the female side fitting part is reduced, and radial play and backlash are reduced. In addition, since an inclined surface is formed on at least one of the first protrusion and the second protrusion, the cylinder is formed along the inclined surface when the vehicle propulsion shaft is extended. The made second shaft can be easily deformed radially inward. Thus, in the state in which the male side fitting portion of the first shaft and the female side fitting portion of the second shaft are completely fitted, the backlash is relatively small, so the male side fitting portion The vehicle propulsion shaft is extended, that is, the gap between the female side fitting part and the female side fitting part is not filled and the backlash increases, that is, the fitting between the male side fitting part and the female side fitting part is In a state in which only a part is made, the shaft end of the second shaft is deformed radially inward to close the gap between the male side fitting portion and the female side fitting portion, thereby reducing rattling. Is done. As a result, the surface pressure applied to the tooth surface and the large diameter portion of the male side fitting portion and the female side fitting portion is increased only when the backlash increases, so the tooth surface and the large diameter portion Wear is suppressed, and a decrease in durability of the vehicle propulsion shaft is suppressed.

  According to the vehicle propulsion shaft of the second aspect of the present invention, since the slit is formed, the shaft end of the second shaft formed in the cylindrical shape can be easily deformed in the radial direction. .

  According to the vehicle propulsion shaft of the invention of claim 3, since the inclined surfaces having the same gradient are formed on both end surfaces of the first protrusion and the second protrusion, respectively, The shaft end of the second shaft formed in a cylindrical shape is smoothly deformed along the inclined surface.

  According to the vehicle propulsion shaft of the invention according to claim 4, the male-side fitting portion and the female-side fitting portion are provided with outer peripheral spline teeth and inner peripheral spline teeth, respectively, and are spline-fitted with each other. Therefore, it can be manufactured relatively easily.

  According to the vehicle propulsion shaft of the fifth aspect of the invention, a so-called large-diameter sliding is achieved in which the tip surface of the outer peripheral spline teeth and the bottom surface of the inner peripheral spline teeth are brought into sliding contact with each other. Therefore, the backlash is reduced compared to the sliding at the small diameter portion.

  According to the vehicle propulsion shaft of the invention of claim 6, foreign matter can be prevented from entering the fitting portion of the male fitting portion and the female fitting portion by the seal member. The deterioration of the durability of the vehicle propulsion shaft due to the adhesion is prevented.

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

  FIG. 1 is a skeleton diagram illustrating the configuration of a front and rear wheel drive vehicle based on a front engine front wheel drive (FF) having a vehicle power transmission device 10 to which the present invention is preferably applied. In FIG. 1, the driving force (torque) generated by the engine 12 that is a driving force source is transmitted to the transfer 22 via the automatic transmission 14. The driving force transmitted to the transfer 22 is distributed to a front wheel differential gear device (front differential) 16 and a propeller shaft 24 which is a driving force transmission shaft. The driving force transmitted to the front wheel differential gear device 16 is transmitted to the pair of left and right front wheels 20l and 20r via the pair of left and right front wheel axles 18l and 18r. On the other hand, the driving force transmitted to the propeller shaft 24 is transmitted to the left and right pair of rear wheels 30l and 30r via the rear wheel differential gear device 26 and the left and right pair of rear wheel axles 28l and 28r.

  The engine 12 is, for example, an internal combustion engine such as a gasoline engine or a diesel engine that generates driving force by combustion of fuel injected in a cylinder. The automatic transmission 14 is, for example, a stepped automatic transmission (automatic transmission) that outputs the rotation input from the engine 12 by decelerating or increasing the speed at a predetermined gear ratio γ. Any one of the first gear, the reverse gear, and the neutral is selectively established, and the speed conversion corresponding to each gear ratio γ is performed. The input shaft of the automatic transmission 14 is connected to the output shaft of the engine 12 via a torque converter (not shown).

  FIG. 2 is a cross-sectional view of an essential part for explaining the structure of the propeller shaft 24 of FIG. The propeller shaft 24 of this embodiment corresponds to the vehicle propulsion shaft of the present invention.

  The propeller shaft 24 includes a bendable universal joint 32, a shaft portion 34, and an intermediate slide portion 36 that are disposed at both left and right ends. One of the universal joints 32 is connected to the transfer 22 side, and the other is connected to the rear wheel differential gear device 26 side. The universal joint 32 is mainly configured by a pair of yokes 38 and 40 and a cross shaft 42 interposed between the yokes 38 and 40. The yokes 38 and 40 are each formed in a bifurcated shape, and the cross shaft 42 is rotatably sandwiched between shaft holes formed in the bifurcated ends of the yokes 38 and 40, respectively.

  The intermediate slide portion 36 can be expanded and contracted in the axial direction in order to cope with a change in the length of the propeller shaft 24. FIG. 3 is an enlarged cross-sectional view of the main part of the intermediate slide portion 36 of FIG. The intermediate slide portion 36 is formed at a connection portion between the end portion of the first shaft 46 and the end portion of the second shaft 48 connected to the shaft portion 34 side in FIG. 2.

  The shaft end portion of the first shaft 46 has a shaft portion 52 centered on the shaft center C and formed with outer peripheral spline teeth, that is, male spline teeth 50 on the outer peripheral surface, and the outer peripheral side of the shaft end of the shaft portion 52. And a cylindrical portion 54 disposed so as to surround the. The cylindrical portion 54 is disposed around a shaft center C that is coaxial with the shaft portion 52, and is integrally connected to the shaft portion 52 so that relative movement in the shaft center direction is impossible. The cylindrical portion 54 is formed separately, for example, and then integrally connected to the first shaft 46 by welding or the like, so that relative movement in the axial direction is impossible. In addition, a cylindrical cylindrical portion 58 in which inner peripheral spline teeth, that is, female spline teeth 56 are formed on the inner peripheral surface is formed at the end of the second shaft 48. When the male spline teeth 50 of the shaft portion 52 of the first shaft 46 and the female spline teeth 56 of the cylindrical portion 58 of the second shaft 48 are spline-fitted, the first shaft 46 and the second shaft 48 are mutually connected. They are connected so that they cannot rotate relative to each other and can move relative to each other in the axial direction, that is, extend and contract. A ring-shaped seal member 59 made of an elastic material such as rubber or resin is provided at the opening end of the cylindrical portion 54 of the first shaft 46 so as to be in sliding contact with the outer peripheral surface of the second shaft 48 formed in a cylindrical shape. Thus, foreign matter such as dust is prevented from entering from the gap between the cylindrical portion 54 of the first shaft 46 and the cylindrical portion 58 of the second shaft 48. The male spline teeth 50 of this embodiment correspond to the male side fitting portion and the outer peripheral spline tooth of the present invention, and the female spline teeth 56 correspond to the female side fitting portion and the inner peripheral spline tooth of the present invention. ing.

  Further, on the inner peripheral surface in the vicinity of the opening end of the cylindrical portion 54, an annular annular protrusion 60 that protrudes radially inward from the inner peripheral surface is provided. An inclined surface 62 having a predetermined gradient is formed on the end surface of the annular protrusion 60 opposite to the opening end side of the cylindrical portion 54. On the other hand, on the outer peripheral surface in the vicinity of the opening end of the cylindrical portion 58, an annular annular protrusion 64 that protrudes radially outward from the outer peripheral surface is provided. An inclined surface 66 having the same gradient as the inclined surface 62 is formed on the end surface of the annular protrusion 64 opposite to the opening end side of the second shaft 48 cylindrical portion 58. Here, the inner peripheral diameter of the inner peripheral surface of the annular protrusion 60 is smaller than the outer peripheral diameter of the outer peripheral surface of the annular protrusion 64, that is, the inner peripheral surface of the annular protrusion 60 is the outer periphery of the annular protrusion 64. It is located radially inward from the surface. Note that the inclined surface 62 of the annular protrusion 60 and the inclined surface 66 of the annular protrusion 64 are steep when the cylindrical portion 58 of the second shaft 48 is rapidly deformed, and gentle when smoothly deforming. Set to slope. Further, the annular protrusion 60 of this embodiment corresponds to the first protrusion of the present invention, and the annular protrusion 64 corresponds to the second protrusion of the present invention.

  4 is a cross-sectional view of the shaft portion 52 of the first shaft 46 and the cylindrical portion 58 of the second shaft 48 shown in FIG. As shown in FIG. 4, the radial gap L is set small so that the tip surface 51 of the male spline tooth 50 of the shaft portion 52 and the bottom surface 57 of the female spline tooth 56 of the cylindrical portion 58 are in sliding contact with each other. This is a so-called large-diameter sliding. Here, the cylindrical portion 58 is formed with slits 68 that are notched in parallel to the plurality of (four in this embodiment) axis C at equal angular intervals. As shown in FIG. 3, the slit 68 is notched to a length that does not exceed the axial length of the female spline teeth 56, for example, and the slit 68 is formed to form a cylinder. The part 58 is easily deformed in the radial direction. When the length of the slit 68 in the axial direction is increased, the second shaft 48 is easily deformed, while the durability of the second shaft 48 is lowered. Further, when the number of slits 68 is increased, the second shaft 48 is easily deformed, while the durability of the second shaft 48 is lowered. Taking these into account, the length and number of the slits 68 are suitably set.

  The function of the intermediate slide part 36 configured as described above will be described. FIG. 3 shows a state where the male spline teeth 50 of the first shaft 46 and the female spline teeth 56 of the second shaft 48 are completely spline-fitted. In this state, since the splines 50 and 56 of each other are completely spline-fitted, the intersecting state (inclined state) of the shaft center of the first shaft 46 and the second shaft 48, i. Is within the set allowable range, and the vibration and noise due to this rattle are within the set allowable range.

  Here, for example, when the propeller shaft 24 is extended in the axial direction during acceleration of the vehicle, the state shown in FIG. 5 is obtained. In FIG. 5, only a part of the male spline teeth 50 of the first shaft 46 and the female spline teeth 56 of the second shaft 48 are fitted. In the process of extending the propeller shaft 24, the inclined surface 62 formed on the annular protrusion 60 of the first shaft 46 and the inclined surface 66 formed on the annular protrusion 64 of the second shaft 48 abut each other. When the propeller shaft 24 is further extended, the cylindrical portion 58 of the second shaft 46 is deformed radially inward along the inclined surface 62. Finally, as shown in FIG. 5, the annular protrusions 60 and 64 get over the inclined surfaces 62 and 66, respectively, and the inner peripheral surface of the annular protrusion 60 and the outer peripheral surface of the annular protrusion 64 come into contact with each other. It will be in the state that was made. In this state, as described above, since the inner peripheral surface of the annular protrusion 60 is positioned radially inward from the outer peripheral surface of the annular protrusion 64, the inner peripheral surface of the annular protrusion 60 is the annular protrusion. 64 outer peripheral surfaces are pressed. As a result, the cylindrical portion 58 of the second shaft 48 is uniformly compressed radially inward and deformed uniformly radially inward. When the cylindrical portion 58 of the second shaft 48 is deformed radially inward, the female spline teeth 56 formed in the cylindrical portion 58 are similarly deformed radially inward, so that the female spline teeth 56 of the cylindrical portion 58 are deformed. And the radial gap L between the first shaft 46 and the male spline teeth 50 are reduced, and radial play and backlash are reduced.

  As described above, according to this embodiment, when the propeller shaft 24 is extended, only a part of the male spline teeth 50 of the first shaft 46 and the female spline teeth 56 of the second shaft 48 are fitted. In this state, the inner peripheral surface of the annular protrusion 60 provided on the cylindrical portion 54 presses the outer peripheral surface of the annular protrusion 64 provided on the second shaft 48, so that it is formed in a cylindrical shape. The shaft end of the second shaft 48 is deformed radially inward. As a result, the radial gap L between the male spline teeth 50 and the female spline teeth 56 is reduced, and radial play and backlash are reduced. Further, since the inclined surfaces 62 and 66 are formed on the annular protrusion 60 and the annular protrusion 64, when the propeller shaft 24 is extended, a cylindrical shape is formed along the inclined surfaces 62 and 66. The two shafts 48 can be easily deformed radially inward. Thus, in the state where the male spline teeth 50 of the first shaft 48 and the female spline teeth 56 of the second shaft 48 are completely fitted, since the rattle is relatively small, the male spline teeth 50 and the female spline teeth In a state where the propeller shaft 24 in which the gap L with respect to 56 is not filled and the backlash is increased, that is, in a state where the fitting between the male spline teeth 50 and the female spline teeth 56 is performed only in part. The shaft end of the second shaft 48 is deformed radially inward to fill the gap L between the male spline teeth 50 and the female spline teeth 56, thereby reducing rattling. As a result, the surface pressure applied to the tooth surfaces and the large diameter portion of the male spline teeth 50 and the female spline teeth 56 is increased only when the backlash is large, so that the wear on the tooth surfaces and the large diameter portion is reduced. It is suppressed and the durability reduction of the propeller shaft 24 is suppressed.

  Further, according to the present embodiment, the slit 68 is formed, whereby the cylindrical portion 58 of the second shaft 48 formed in a cylindrical shape can be easily deformed in the radial direction.

  In addition, according to the present embodiment, since the inclined surfaces 62 and 66 having the same gradient are formed on both end surfaces of the annular protrusion 60 and the annular protrusion 64, respectively, the cylindrically formed first The cylindrical portion 58 of the biaxial 48 is smoothly deformed along the inclined surface.

  In addition, according to the present embodiment, the shaft portion 52 and the cylindrical portion 58 are respectively provided with the male spline teeth 50 and the female spline teeth 56 and are spline-fitted with each other, and therefore can be manufactured relatively easily. .

  Further, according to the present embodiment, since the tip surface 51 of the male spline tooth 50 and the tooth bottom surface 57 of the female spline tooth 56 are in sliding contact with each other, so-called large-diameter sliding is achieved. Key play is reduced compared to sliding.

  Further, according to the present embodiment, the male spline teeth are provided by interposing the seal member 59 between the open end of the cylindrical portion 54 of the first shaft 46 and the outer peripheral surface of the cylindrical portion 58 of the second shaft 48. Intrusion of foreign matter into the fitting portion between the female spline teeth 50 and the female spline teeth 56 is prevented, and deterioration in durability of the intermediate slide portion 36 due to adhesion of foreign matter is prevented.

  As mentioned above, although the Example of this invention was described in detail based on drawing, this invention is applied also in another aspect.

  For example, the propeller shaft 24 of the present embodiment is an example of the vehicle propulsion shaft of the present invention, but the vehicle propulsion shaft is not limited to the propeller shaft 24, and other vehicle propulsion shafts such as a drive shaft. The present invention may also be applied to.

  Further, the spline fitting of the present embodiment is a so-called large-diameter sliding in which the tip surface 51 of the male spline tooth 50 and the bottom surface 57 of the female spline tooth 56 are in sliding contact with each other. A configuration in which the bottom surface of the male spline teeth 50 and the top surface of the female spline teeth 56 are in sliding contact with each other may be employed, and the invention is not necessarily limited to large-diameter sliding.

  In addition, the annular protrusion 60 and the annular protrusion 64 of the present embodiment are formed with the inclined surface 62 and the inclined surface 66, respectively. However, the annular protrusion 60 and the annular protrusion 64 are not necessarily formed on both. Only one of them may be used.

  In addition, the fitting portion of the first shaft 46 and the second shaft 48 of the present embodiment is not relatively rotatable by spline fitting and can be moved in the axial direction. For example, other fitting methods such as serration are used. However, any other configuration may be used as long as the first shaft 46 and the second shaft 48 are not rotatable relative to each other and are movable in the axial direction.

  The vehicle power transmission device 10 of the present embodiment is a front and rear wheel drive vehicle based on front engine front wheel drive, but the present invention is not limited to front and rear wheel drive vehicles, and the front engine rear wheel drive. The present invention can also be applied to a type vehicle (FR type vehicle).

  Moreover, although the cross-sectional shape of the tooth | gear part of the male spline tooth | gear 50 of this Example and the female spline tooth | gear 56 is formed in substantially rectangular shape, for example, a general involute spline shape etc. may be sufficient and the shape of a tooth | gear is not specifically limited.

  In addition, the slits 68 of this embodiment are provided at four equiangular intervals in parallel with the axis C, but the shape and number of slits are not necessarily provided at four places in parallel with the axis C. For example, three positions may be provided inclined with respect to C. That is, the shape and number of the slits 68 can be freely set within a consistent range as long as the cylindrical portion 58 of the second shaft 48 is easily deformed.

  The above description is only an embodiment, and the present invention can be implemented in variously modified and improved forms based on the knowledge of those skilled in the art.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a skeleton diagram illustrating a configuration of a front and rear wheel drive vehicle based on a front engine front wheel drive having a vehicle power transmission device to which the present invention is preferably applied. It is principal part sectional drawing for demonstrating the structure of the propeller shaft of FIG. It is principal part sectional drawing to which the intermediate | middle slide part of FIG. 2 was expanded. It is A sectional view taken on the line A of the first axis and the second axis of FIG. FIG. 3 shows a state in which only a part of the first shaft male spline and the second shaft female spline are fitted, and corresponds to FIG. 3.

Explanation of symbols

  24: Propeller shaft (vehicle propulsion shaft) 46: First shaft 48: Second shaft 50: Male spline teeth (male side fitting portion) 51: Tooth surface 54: Cylindrical portion 56: Female spline teeth (female side fitting) 57: Tooth bottom 59: Seal member 60: Annular protrusion (first protrusion) 62: Inclined surface 64: Annular protrusion (second protrusion) 66: Inclined surface 68: Slit

Claims (6)

A first shaft in which a male fitting portion is formed on the outer peripheral surface of the shaft end, and a second shaft in which the shaft end portion is formed in a cylindrical shape and a female fitting portion is formed on the inner peripheral surface thereof. The vehicular propulsion is configured such that the male-side fitting portion of the first shaft and the female-side fitting portion of the second shaft are fitted to each other so that they can be expanded and contracted in the axial direction and cannot be relatively rotated. An axis,
On the outer peripheral side of the shaft end of the first shaft, a cylindrical portion that is not movable relative to the first shaft in the axial direction is disposed on the same axis.
In the vicinity of the opening end of the cylindrical portion, an annular first protrusion that protrudes radially inward from the inner peripheral surface of the cylindrical portion is provided,
In the vicinity of the opening end of the second shaft formed in the cylindrical shape, an annular second protrusion projecting radially outward from the outer peripheral surface is provided,
The inner peripheral diameter of the first protrusion is smaller than the outer peripheral diameter of the second protrusion,
An inclined surface is formed on at least one of the end surface of the first protrusion opposite to the opening side of the cylindrical portion and the end surface of the second protrusion opposite to the opening side of the second shaft. The propulsion shaft for vehicles characterized by being made.   2. The vehicle propulsion shaft according to claim 1, wherein a plurality of slits cut out in an axial direction are formed at a shaft end of the cylindrical second shaft. 3.   An inclined surface having the same gradient is provided on both the end surface of the first protrusion opposite to the opening side of the cylindrical portion and the end surface of the second protrusion opposite to the opening side of the second shaft. The vehicle propulsion shaft according to claim 1, wherein the vehicle propulsion shaft is formed respectively.   4. The vehicle according to claim 1, wherein the male-side fitting portion and the female-side fitting portion are provided with outer peripheral spline teeth and inner peripheral spline teeth, respectively, and are spline-fitted with each other. Propulsion axis.   5. The vehicle propulsion shaft according to claim 4, wherein a tooth tip surface of the outer peripheral spline teeth and a tooth bottom surface of the inner peripheral spline teeth are in sliding contact with each other.   6. The vehicle propulsion shaft according to claim 1, wherein a seal member that is in sliding contact with an outer peripheral surface of the second shaft is provided at an opening end of the cylindrical portion.

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