JP2000074085A - Tripod type constant velocity joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce manufacturing cost by miniaturizing a tripod type constant velocity joint. SOLUTION: A roller 30 is supported on two trunnions 21 radially projected from an inner member 20 through a large number of needles 35 free to rotate and free to move in the axial direction, and an outer peripheral part of the roller is engaged with a guide groove 11 of an outer member 10 free to roll. Each of the needles is held in a storage groove 32 formed on an inner peripheral surface 31 of the roller free to roll and so as to constrain movement in the axial direction, and a falling stop structure 24 provided on outer end parts of the trunnions makes contact only with the needles without making contact with the roller and prevents falling of the roller from the trunnions. The falling stop structure can be a snap ring 26 engaged with a ring groove 25 formed on an outer peripheral surface of a head end part of the trunnion or a projected part 27 formed by calking on the head end part of the trunnion and projected in the radial direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tripod type constant velocity joint used for a driving force transmitting portion between a differential gear device and a driving wheel of an automobile.

[0002]

2. Description of the Related Art A tripod type constant velocity joint of this type rotatably supports a roller 2 via a needle 3 on three trunnions 21 projecting radially from an inner member 20, as shown in FIG. In some cases, the outer peripheral portion of each roller 2 is rollably engaged with three guide grooves 1 formed in the inner surface of the outer member 10 in the axial direction. In this constant velocity joint, each roller 2 can be freely moved in the axial direction with respect to the trunnion 21, and corresponds to the relative movement in the axial direction between each roller 2 and the trunnion 21 when the joint is used in a state having an intersection angle. . In addition, trunnion 21
A press retainer 4 is provided at the distal end of the press retainer 4 which is retained by a snap ring 5 engaged with an annular groove 5a. The roller 2 and the needle 3 abut against the open distal end and the root of the press retainer 4, respectively. It is prevented from getting out of the trunnion 21.

In the prior art shown in FIG. 8, the rollers 2 are inner rollers 2 rotatably fitted to each other via a spherical surface.
a and the outer roller 2b, and the inner roller 2a
The inner peripheral surface of the outer roller 2b is supported by the trunnion 21 via the needle 3, and the outer peripheral portion of the outer roller 2b can be rolled into the guide groove 1 of the outer member 10. However, in the prior art shown in FIG. The inner peripheral surface is supported by the trunnion 21 via the needle 8, and the outer peripheral portion is the outer member 1.
It is possible to roll into the 0 guide groove 1. Further, in this prior art, similarly to the prior art shown in FIG. 8, each roller 7 is movable in the axial direction with respect to the trunnion 21.
The cutting retainer 9 is used in place of the press retainer 4 to prevent the needle 8 from coming out of the trunnion 21 more than necessary.

In FIGS. 4 and 5 of Japanese Utility Model Application Laid-Open No. 2-94928, a needle accommodating groove is provided in a trunnion, and a circlip that can move in the axial direction of the trunnion and abuts only on the roller prevents the roller and needle from coming off. You are.

[0005]

In the prior art shown in FIGS. 8 and 9, when the crossing angle of the joint is large, the rollers 2, 7 and the retainers 4, 9 come into contact with each other to limit the maximum joint angle. There is. In order to avoid this, it is conceivable to increase the length of the trunnion 21 to increase the axial movement amount of the rollers 2 and 7 with respect to the trunnion 21. However, the length of the trunnion 21 increases and the outer member 10 There is a problem that the outer diameter becomes large. In addition, the retainers 4, 9 function as stoppers for both the rollers 2, 7 and the needles 3, 8, so they have a complicated shape despite their small size, and require high-precision pressing and cutting. Therefore, there is a problem that the cost of the tripod type constant velocity joint is increased.

In the technique disclosed in Japanese Utility Model Laid-Open No. 2-94928, there is a problem that when the roller moves outward in the axial direction of the trunnion, the contact area with the needle becomes small, causing seizure and shortening the life. Furthermore, since the circlip is movable in order to secure the amount of movement of the roller, the trunnion becomes longer in the axial direction, and the joint becomes larger (if the circlip can be moved without increasing the length of the trunnion). However, the needle becomes short and the surface pressure increases). An object of the present invention is to solve each of these problems.

[0007]

According to a first aspect of the present invention, there is provided a tripod-type constant velocity joint comprising: an outer member having three guide grooves formed in an inner surface thereof in an axial direction; and an inner member disposed inside the outer member. An inner member having three trunnions protruding into each guide groove, and a central portion is rotatably and axially movably supported by each trunnion via a number of needles, and an outer peripheral portion is provided on each of the guide grooves. In a tripod-type constant velocity joint including three rollers that are rollably engaged with each other, the needles formed on the inner peripheral surface of the rollers are held so as to freely roll and restrain the movement in the axial direction. The retaining groove is provided at an outer end of the trunnion and is provided at an outer end of the trunnion. The retaining groove contacts the needle only without contacting the roller to prevent the roller from falling out of the trunnion. It is characterized in that it comprises a structure.

According to the second aspect of the present invention, the tripod-type constant velocity joint retaining structure comprises an annular groove formed on the outer peripheral surface of the tip of the trunnion and a snap ring engaged with the annular groove. Preferably.
Alternatively, the retaining structure may be at least one protruding portion which is formed by caulking at the tip of the trunnion and protrudes in the radial direction, and in this case, the present invention is described in claim 4. As described above, it is preferable that the trunnion is formed with a groove closer to the root side than the portion forming the protrusion at the tip end.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a first embodiment of a tripod type constant velocity joint according to the present invention will be described with reference to FIGS. This tripod-type constant velocity joint includes an outer member 10 having three guide grooves 11 formed in the inner surface in the axial direction and an integral shaft portion 12, and a boss portion disposed inside the outer member 10. An inner member 20 having three trunnions 21 radially protruding into each guide groove 11, and a central portion supported by each trunnion 21 via a number of needles 35 so as to be rotatable and axially movable. At the same time, three rollers 30 whose outer peripheral portions are rotatably engaged with the respective guide grooves 11 are main components, and a drive shaft 29 is spline-coupled to the boss of the inner member 20.

Each guide groove 11 of the outer member 10 has a concave cross section facing each other and extends in the axial direction parallel to each other.
It has a pair of track surfaces 11a. Further, the roller 30 of this embodiment includes an inner roller 30a and an outer roller 30a.
b, the inner peripheral surface of the outer roller 30b, which is also a true spherical surface, is fitted with a slight gap to the outer peripheral surface of the inner roller 30a, which is a perfect spherical surface.
a and 30b are concentrically rotatably engaged with each other. A storage groove 32 is formed on the inner peripheral surface 31 of the inner roller 30a so as to rotatably store a large number of needles 35 and restrains movement in the axial direction. The depth of the storage groove 32 is smaller than the thickness of the needle 35. , Along both sides of the relief 3
2a is formed. The inner roller 30a is rotatably and axially movably supported by the trunnion 21 via the needle 35, and the outer peripheral surface of the outer roller 30b has a convex sectional shape corresponding to the track surface 11a of the guide groove 11, and the track surface 11a. And is engaged with the guide groove 11 so that only rolling can be performed.

Next, the retaining structure 24 for preventing the roller 30 from coming off the trunnion 21 will be described. A snap ring 26 formed by cutting a metal wire having a circular cross section into a cutout circle is elastically locked in an annular groove 25 formed on the outer peripheral surface of the tip portion of the trunnion 21. The outer diameter of the snap ring 26 is equal to that of the inner roller 30a. When the roller 30 supported by the trunnion 21 is moved outwardly, the snap ring 26 enters the inner peripheral surface 31 without contacting the inner roller 30a as shown in FIG. ,
The needle 35 and the roller 30 are stopped from moving in direct contact with the needle 35 held in the storage groove 32.
In this state where the movement of the roller 30 is stopped, the intersection angle (the intersection angle of the joint) between the shaft portion 12 of the outer member 10 and the drive shaft 29 is maximized. The annular groove 25 and the snap ring 26 constitute the retaining structure 24 according to the first embodiment.

According to the first embodiment, the roller 3
0 moves axially outward with respect to the trunnion 21, the snap ring 26 of the retaining structure 24
The roller 35 enters the inner peripheral surface 31 without contacting the needle 35 and contacts only the needle 35 to prevent the needle 35 and the roller 30 from coming out of the trunnion 21 in the axial direction. In this abutted state, the snap ring 26 enters the inner peripheral surface 31 of the roller 30, so that the amount of movement of the roller 30 relative to the trunnion 21 in the axial direction is increased, and the joint intersection angle is less likely to be restricted. Further, the length of the trunnion 21 for locking the snap ring 26 can be shortened by an amount corresponding to the snap ring 26 entering the inner peripheral surface 31 of the roller 30, and the outer diameter of the outer member 10, that is, a tripod type, etc. The outer diameter of the entire speed joint can be reduced. Further, even if the roller 30 moves in the axial direction with respect to the trunnion 21, the needle 35 held in the storage groove 32 of the roller 30 does not change the length of contact with the trunnion 21, and therefore the contact area does not change. The reduction in the size does not cause seizure or shorten the life.

The second embodiment shown in FIG. 4 and FIG.
Since only the retaining structure 24 is different from that of the first embodiment, the same portions are simply denoted by the same reference numerals,
Only the differences will be described. The retaining structure 24 according to the second embodiment is formed by crimping two diametrically opposed distal end edges of the trunnion 21 from the axial direction while the roller 30 is supported by the trunnion 21 together with the needle 35. Two protruding portions 27 that protrude in the radial direction are formed. The circumferential width of the protrusion 27 is substantially the same as the diameter of the needle 35, and the protrusion amount is the trunnion 21.
Is slightly smaller than the gap between the outer peripheral surface of the inner roller 30a and the inner peripheral surface 31 of the inner roller 30a. When the roller 30 moves outward with respect to the trunnion 21, each protrusion 27 enters the inner peripheral surface 31 without contacting the inner roller 30a, and directly contacts the needle 35 held in the storage groove 32. And the needle 3
5 and the movement of the roller 30 are stopped.

Also in the second embodiment, the retaining structure 2
The protrusion 27 of the roller 4 enters the inner peripheral surface 31 of the roller 30 and abuts only on the needle 35 to contact the needle 35 and the roller 30.
Is prevented from slipping out of the trunnion 21 in the axial direction, so that the protruding portion 27 enters the inner peripheral surface 31 of the roller 30 in the contact state, and the axial movement amount of the roller 30 relative to the trunnion 21 becomes large. Therefore, similarly to the first embodiment, the joint crossing angle is less likely to be restricted, and the length of the trunnion 21 can be reduced. Therefore, the outer diameter of the entire tripod-type constant velocity joint can be reduced accordingly. it can. Further, in the second embodiment, since the snap ring 26 and the annular groove 25 for attaching the snap ring are not required, the manufacturing cost is reduced as compared with the first embodiment. The number of the protruding portions 27 is not limited to two as shown, but may be one or three or more.

The third embodiment shown in FIG. 6 and FIG.
The only difference from the second embodiment is that an annular groove 28 is formed in the trunnion 21 closer to the root side than the portion forming the protrusion 27 at the tip of the trunnion 21.
In the second embodiment, a protrusion 2 formed by caulking
7, the root portion on the side of the needle 35 does not rise at a right angle from the outer peripheral surface of the trunnion 21, and some roundness is unavoidable.
The leading end of the roller 5 rides on this round portion, and the accuracy of the position where the movement of the roller 30 in the axial direction is stopped may be reduced.

However, in the third embodiment,
Since the trunnion 21 is provided with the groove 28 closer to the root side than the part where the protruding part 27 is formed, deformation by caulking for forming the protruding part 27 does not extend to the trunnion 21 which is closer to the root side than the groove 28. Absent. Therefore, since a round portion is not formed at the root portion on the needle 35 side of the protruding portion 27 formed by caulking, the flatness of the protruding portion 27 at the root side is improved. As a result, the roller 30 stops moving in the axial direction when the distal end surface of the needle 35 comes into direct contact with the protruding portion 27, so that the accuracy of the stop position is improved, and accordingly, the accuracy of the maximum intersection angle of the joint is also improved. I do. Other configurations and operations are the same as those of the second embodiment, and thus detailed description is omitted. The groove 28 is not limited to the annular groove as shown in the figure, and may be a groove formed in the tangential direction on the root side from each part forming the protrusion 27 of the trunnion 21. In each of the above embodiments, Inner roller 30a and outer roller 30b rotatably fitted to each other
Although the example using the roller 30 is described, the present invention can also be carried out using an integrally formed roller (for example, see the prior art roller 7 shown in FIG. 9).

[0017]

According to the present invention, the retaining structure abuts only on the needle to prevent the roller from coming out of the trunnion in the axial direction. And the amount of axial movement of the roller relative to the trunnion can be increased accordingly. For this reason, it is difficult to restrict the intersection angle of the joint, and the length of the trunnion can be shortened. .
In addition, the needle held in the groove of the roller does not change the contact area with the trunnion even if the roller moves in the axial direction with respect to the trunnion. It does not decline.

Further, according to the retaining structure comprising the annular groove formed in the outer peripheral surface of the front end portion of the trunnion and the snap ring locked in the annular groove, the retainer having a complicated shape can be used. Since it is not necessary, the manufacturing cost of the tripod type constant velocity joint can be reduced.
According to this retaining structure, at least one protruding portion which is formed by caulking at the tip of the trunnion and protrudes in the radial direction, the snap ring and the annular groove for attaching the snap ring are not required. The cost can be further reduced. According to the groove formed closer to the root side than the portion forming the protrusion, the manufacturing cost increases by the amount of forming the groove as compared with the above-mentioned one, but the manufacturing cost on the root side of the protrusion is increased. Since the flatness is improved, the accuracy of the stop position of the roller by the protrusion and the maximum intersection angle of the joint is improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a first embodiment of a tripod type constant velocity joint according to the present invention.

FIG. 2 is a partially enlarged sectional view taken along line 2-2 of FIG.

FIG. 3 is a partially enlarged cross-sectional view similar to FIG. 2 in a state where a roller has moved most outward in a radial direction.

FIG. 4 is a partially enlarged sectional view corresponding to FIG. 2 of a second embodiment of a tripod type constant velocity joint according to the present invention.

FIG. 5 is an end view of the trunnion of the second embodiment as viewed from the outside in the radial direction.

FIG. 6 is a partially enlarged sectional view corresponding to FIG. 2 of a third embodiment of a tripod type constant velocity joint according to the present invention.

FIG. 7 is an end view of the trunnion of the third embodiment as viewed from the outside in the radial direction.

FIG. 8 is a partially enlarged sectional view corresponding to FIG. 2 of an example of a tripod type constant velocity joint according to the related art.

FIG. 9 is a partially enlarged sectional view corresponding to FIG. 2 of another example of the tripod type constant velocity joint according to the related art.

[Explanation of symbols]

10: outer member, 11: guide groove, 20: inner member,
21: trunnion, 24: retaining structure, 25: annular groove,
26 Snap ring, 27 Projection, 28 Groove, 30
... rollers, 31 ... inner peripheral surface, 32 ... storage grooves, 35 ... needles.

Claims (4)

[Claims] 1. An outer member having three guide grooves formed on an inner surface thereof in the axial direction, an inner member disposed inside the outer member and having three trunnions protruding into each of the guide grooves, and A tripod type or the like including three rollers whose central portion is rotatably and axially movably supported by each of the trunnions via a needle, and whose outer peripheral portion is rotatably engaged with each of the guide grooves. In the speed joint, a housing groove formed on the inner peripheral surface of the roller and holding the needles so as to be able to roll and restrain movement in the axial direction is in contact with the roller provided at the outer end of the trunnion. A tripod-type constant velocity joint, comprising a retaining structure for preventing the roller from coming out of the trunnion by contacting only the needle without contacting the needle. 2. The tripod constant velocity joint according to claim 1, wherein said retaining structure comprises an annular groove formed in an outer peripheral surface of a tip portion of said trunnion, and a snap ring locked in said annular groove. 3. The tripod-type constant velocity joint according to claim 1, wherein the retaining structure is at least one protruding portion formed by caulking at a tip end of the trunnion and protruding in the radial direction. 4. The tripod constant velocity joint according to claim 3, wherein the trunnion has a groove formed closer to a root side than a portion of the trunnion where the protrusion is formed.