JP2006258177A - Tripod constant velocity universal joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent adverse effect on the strength of the journal root part of a tripod constant velocity universal joint by shifting a forging parting line without removing the forging parting line. <P>SOLUTION: The forging parting line P of a tripod is separated from an outermost edge line (tripod center plane D) so as not to be overlapped with the circumferential outermost edge line of the tripod 5 at least in the root part of a trunnion journal 8. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The tripod constant velocity universal joint according to the present invention is incorporated in, for example, a drive system of an automobile, and transmits torque at a constant angular speed between two rotating shafts that exist on a non-linear line.

  A tripod type constant velocity universal joint 1 as shown in FIG. 9 is widely used in a drive system of an automobile (see, for example, Patent Document 1). This tripod type constant velocity universal joint 1 includes a hollow cylindrical housing 3 fixed to an end of a first rotating shaft 2 such as a drive shaft, and an end of a second rotating shaft 4 such as a wheel-side rotating shaft. It is comprised from the tripod 5 fixed to a part.

  A concave groove 6 extending in the axial direction of the housing 3 is formed on the inner peripheral surface of the housing 3 at a position equally divided into three in the circumferential direction. On the other hand, the tripod 5 is composed of a boss 7 for fixing to the end of the second rotating shaft 4 and a cylindrical trunnion journal 8 projecting in a radial direction from a circumferentially divided position of the boss 7. ing. The cross section of each trunnion journal 8 is an ellipse having a major axis in the circumferential direction of the joint. Further, the outer peripheral surface of the trunnion journal 8 is a straight line parallel to the axial direction of the journal in a side view as shown in FIG. A double roller type roller cassette is fitted to the outer peripheral surface of the trunnion journal 8. The roller cassette 9 includes an inner roller 9a, an outer roller 9b, and a plurality of needle rollers 9c sandwiched between inner and outer rollers. Retainer rings 9d are fitted to the inner and outer end positions of the inner peripheral portion of the outer roller 9b, and the inner rollers 9a and the needle rollers 9c are prevented from being removed by the retainer ring 9d. The roller cassette 9 is rotatable around the trunnion journal 8, and an outer roller 9 b of the roller cassette 9 is fitted between a pair of arcuate guide surfaces 6 a constituting the concave groove 6 of the housing 3.

  When the tripod type constant velocity universal joint 1 configured as described above is used, for example, when the first rotary shaft 2 rotates, the rotational force is generated from the housing 3 to the outer roller 9b of the roller cassette 9, the needle rollers 9c, It is transmitted to the boss 7 of the tripod 5 via the inner roller 9a and the trunnion journal 8, and the second rotating shaft 4 is rotated. When the center axis of the first rotating shaft 2 and the center axis of the second rotating shaft 4 do not coincide with each other, that is, when the tripod constant velocity universal joint 1 takes an operating angle, both rotating shafts 2, 4, each trunnion journal 8 is tilted and displaced in the joint axial direction within the inner roller of the roller cassette 9. At this time, the outer roller 9 b of the roller cassette 9 supported on each trunnion journal 8 rolls on the guide surface 6 a of the concave groove 6, and the entire roller cassette 9 is relatively displaced in the axial direction of the trunnion journal 8. These movements ensure constant velocity between the first and second rotating shafts 2 and 4 as is well known.

JP-A-62-233522

 As a method for producing tripods, cold forging is usually employed. The strength of the cold-forged tripod is further improved by quenching. As a mold used for this cold forging, a pair of molds that can be divided with a plane including the three axes of the trunnion journal 8 (hereinafter referred to as “tripod center plane”) as a boundary is usually used. In such a mold, since the mold impression becomes discontinuous at the dividing surface portion, the parting line P inevitably remains on the surface of the tripod after forging as shown in FIG. The position of the parting line P is a position where the surface of the tripod 5 and the tripod center plane intersect. In FIG. 11, reference numeral 10 denotes a ground surface obtained by grinding the outer peripheral surface of the trunnion journal 8 and the portion in contact with the inner peripheral surface of the inner roller 9 a.

  By the way, when torque is transmitted from the housing 3 to the tripod 5 via the roller cassette 9, stress is concentrated on the roots (three places) of the journal 8 in the tripod center plane D of FIG. Therefore, it is necessary to reduce as much as possible minute irregularities and scratches that increase the notch coefficient on the surface layer of the journal root where stress is concentrated.

 However, when the tripod 5 is forged as described above, a forging parting line P is generally formed on the surface layer portion of the tripod center plane D if a mold that bisects the tripod center plane D is used. The Since this forged parting line P is raised on the surface of the tripod center plane D and the surface of the forged parting line P is irregularly uneven, the notch coefficient of the journal root in the tripod center plane D is determined. It will be very high. Furthermore, an incompletely hardened layer is likely to be generated in the forged parting line P and its vicinity after the heat treatment. If there are many incompletely hardened layers in the forging parting line P at the root of the journal, cracks tend to occur starting from the incompletely hardened layer when excessive torque is input to the tripod.

 Thus, when the forging parting line P exists at the journal root in the tripod center plane, when excessive torque is input to the tripod 5, the journal root in the tripod center plane starts from static fracture and fatigue fracture. There is a problem that the tripod 5 is liable to break due to the progress of cracks. For this reason, the forging parting line P is removed as needed by cutting, shot blasting, barrel processing, etc. after forging and before heat treatment.

  The object of the present invention is to stop the forging parting line from being costly removed by cutting, shot blasting, barrel processing, etc., and instead, adversely affecting the strength of the journal root by shifting the position of the parting line. It is to prevent it from reaching.

  In order to achieve the above object, the invention according to claim 1 is the first rotary shaft having a concave groove that is opened on one end side in the axial direction and that extends in the axial direction at the circumferentially equally divided position of the inner peripheral surface. Forging comprising a hollow cylindrical housing fixed to the end, a boss fixed to the end of the second rotating shaft, and a trunnion journal projecting radially from the bisector of the boss in the circumferential direction. In the tripod type constant velocity universal joint, which has a tripod formed integrally at the outer peripheral surface of the trunnion journal, and a roller which is accommodated in the groove of the housing and can roll in the axial direction of the housing. The parting line is separated from the outermost edge line so as not to overlap the outermost edge line in the circumferential direction of the tripod at least at the root portion of the trunnion journal.

  According to a second aspect of the present invention, in the first aspect of the present invention, the forged parting line of the tripod is connected to the outermost peripheral line from the outermost peripheral line so as not to overlap the circumferential outermost peripheral line of the tripod at the root portion of the trunnion journal. A tripod type constant velocity universal joint characterized in that it is translated in parallel in the direction.

 In short, the forged parting line may be shifted only in the journal root portion in the axial direction of the joint, or the entire forged parting line may be shifted in parallel from the dividing surface in the axial direction of the joint. The amount of movement of the forging parting line is sufficient so long as it does not overlap the outermost circumferential line of the tripod, so that the design of the cold forging die can be changed little.

  Thus, by preventing the forged parting line from overlapping the circumferential outermost line of the tripod, it is possible to prevent cracks from occurring and progressing in the forged parting line at the journal root.

 Here, the “tripod circumferential outermost line” is a line in which the tripod center plane intersects the surface of the tripod.

  By preventing the forging parting line P from being formed at the journal root in the tripod center plane during forging, the notch coefficient of the journal root surface layer increases due to the presence of the forging parting line P in the tripod center plane, The increase in imperfectly hardened layer at the root of the journal in the tripod center plane can be prevented, and when the excessive torque is input, the lack of strength of the tripod where the journal root in the tripod center plane becomes the starting point of failure should be resolved. Leads to.

 Conventionally, in order to prevent a reduction in the strength of the tripod due to the presence of the forged parting line, it has been necessary to secure the thickness of the journal base or to perform post-processing to remove the forged parting line. Since the problem of crack propagation starting from a forged parting line or an incompletely hardened layer is solved, the thickness of the journal root can be reduced, and the tripod can be reduced in weight and size. Moreover, since the removal process of a forging parting line becomes unnecessary and a tripod can be used with a cold forming surface, there is also an effect that the cost for the parting line removal process can be saved.

 Hereinafter, embodiments of the present invention will be described with reference to the drawings. The tripod type constant velocity universal joint according to the first embodiment of the present invention is structurally substantially the same as the conventional tripod type constant velocity universal joint shown in FIGS. The only difference is the position of the forging parting line, and the rest of the configuration is the same as in FIGS.

 That is, as shown in FIG. 2, the tripod type constant velocity universal joint includes a hollow cylindrical housing 3 fixed to the end of the first rotating shaft 2 such as a drive shaft, and a wheel-side rotating shaft and the like. The tripod 5 is fixed to the end of the second rotating shaft 4. A concave groove 6 extending in the axial direction of the housing 3 is formed on the inner circumferential surface of the housing 3 at a position equally divided into three in the circumferential direction. On the other hand, the tripod 5 is composed of a boss 7 for fixing to the end of the second rotating shaft 4 and a cylindrical trunnion journal 8 projecting in a radial direction from a circumferentially divided position of the boss 7. The The cross section of each trunnion journal 8 is an ellipse having a long axis in the circumferential direction of the joint. Further, as shown in FIG. 2, the outer peripheral surface of the trunnion journal 8 has a linear shape parallel to the axial direction of the journal in a side view. A double roller type roller cassette 9 is fitted to the outer peripheral surface of the trunnion journal 8. The roller cassette 9 includes an inner roller 9a, an outer roller 9b, and a plurality of needle rollers 9c interposed between the inner and outer rollers. A retainer ring 9d is fitted to both the inner and outer end positions of the inner peripheral portion of the outer roller 9b, and the inner roller 9a and the needle roller 9c are prevented from being detached by the retainer ring 9d. The roller cassette 9 is rotatable around the trunnion journal 8, and an outer roller 9 b of the roller cassette 9 is fitted between a pair of arcuate guide surfaces 6 a constituting the concave groove 6 of the housing 3.

 The forging parting line P on the surface of the tripod 5 is left as it is as a cold-formed surface without being removed by cutting, shot blasting, barrel treatment or the like after forging. As shown in FIGS. 1A to 1C, the parting line P is a line (the outermost circumferential edge of the tripod in the circumferential direction) where the tripod center plane D including the axis of the three journals 8 and the surface of the tripod 5 intersect. Line). That is, the conventional parting line P is formed so as to completely overlap the line where the tripod center plane D and the tripod 5 surface intersect as shown in FIG. 11C. The tripod center plane D or a crossing line is translated several millimeters so as not to overlap the crossing line at all. By doing in this way, the crack progress starting from the parting line P of the journal root is prevented. The direction of translation of the parting line P is the right side in FIG. 1C, but may be the opposite left side.

 Next, a modification of the first embodiment of the present invention will be described based on FIG. In this embodiment, most of the parting lines P are kept overlapped with the intersection lines as in the prior art, and only the parting lines P at the journal base are separated by several millimeters so as not to overlap the intersection lines. The separating direction is the right side in FIG. 3C, but it may be the opposite left side.

 Next, a second embodiment of the present invention will be described based on FIG. 4 and FIG. In the second embodiment, the journal and the roller cassette are different from those in FIG. That is, the outer peripheral surface of the journal 8a is not a straight line but a convex surface in a side view as shown in FIG. The inner peripheral surface of the inner roller 19a of the roller cassette 19 is a concave spherical surface. A configuration in which both inner circumferential convex surfaces of the journal 8a are fitted to the concave spherical surface of the inner roller 19a so that the inner roller 19a is prevented from being removed and the journal 8a is allowed to swing in the joint axial direction with respect to the inner roller 19a. It has become. A notch plane 20 is formed at the tip of the journal 8a, as shown in FIG. 5C, to prevent interference with the inner roller 19a when the roller cassette 19 is fitted to the journal 8a at an angle. The outer roller 19 b rolls along the guide surface 22 a of the concave groove 22 while the outer flange portion 21 of the outer roller 19 b is slidingly guided by the guide shoulder 22 b of the concave groove 22. The needle roller 19c is retained by the outer flange 21 of the outer roller 19b.

 In such a tripod type constant velocity universal joint, the forging parting line P is several millimeters parallel to the joint axis direction from the center plane D so as not to overlap the tripod center plane D as shown in FIGS. Moved. The direction of translation is the right side in FIG. 5C, but may be the opposite left side.

 Next, a third embodiment of the present invention will be described with reference to FIGS. This embodiment differs from that of FIG. 1 in that no roller cassette is used and a single roller 30 is used. The outer peripheral surface of the journal 8b is straight when viewed from the side, but the circlip 31 and the retainer ring 32 are attached to the annular groove on the tip end side, and the retainer ring 32 prevents the needle rollers 33 from being removed. The outer peripheral surface of the roller 30 is a convex spherical surface, and is fitted to the guide surface 34a of the concave groove 34 having the same curvature. In this tripod type constant velocity universal joint, the roller 30 is linearly movable in the direction of the concave groove 34 and swingable in the joint axial direction.

 In such a tripod type constant velocity universal joint, the forging parting line P is translated several millimeters from the center plane D so as not to overlap the tripod center plane D as shown in FIG. The direction of translation is the right side in FIG. 6B, but may be the opposite left side.

 Next, a fourth embodiment of the present invention will be described with reference to FIGS. This embodiment differs from that of FIG. 1 in that no roller cassette is used and a single roller 40 is used. The outer peripheral surface of the journal 8 c is a straight line when viewed from the side, and the roller 40 is fitted through the cylindrical roller 41. The outer peripheral surface of the roller 40 is a convex spherical surface that is slightly narrower than the inner peripheral surface, and is fitted to a guide surface 42 a having the same curvature of the concave groove 42. In this tripod type constant velocity universal joint, the roller 40 is linearly movable in the direction of the concave groove 42 and is swingable in the joint axial direction.

 In such a tripod type constant velocity universal joint, the forged parting line P is translated several millimeters from the center plane D so as not to overlap the tripod center plane D as shown in FIG. The direction of the parallel movement is the right side in FIG. 7B, but may be the opposite left side.

 Next, a fifth embodiment of the present invention will be described with reference to FIGS. This embodiment uses a roller cassette 50 as in FIG. 1, but differs from FIG. 1 in that the outer peripheral surface of the journal 8d is a spherical surface. Accordingly, the outer peripheral surface of the journal 8d is a convex curved surface in a side view. The roller cassette 50 includes an inner roller 50a, an outer roller 50b, needle rollers 50c, and a retainer ring 50d.

 The inner peripheral surface of the inner roller 50a is a straight line when viewed from the side, and both ends of the outer peripheral surface of the journal 8d in the joint circumferential direction are fitted to the inner peripheral surface. The outer peripheral surface of the outer roller 50b is a convex spherical surface, and is fitted to the guide surface 51a having the same curvature of the concave groove 51. In this tripod type constant velocity universal joint, the roller cassette 50 is prevented from swinging in the axial direction of the joint by the outer flange 52 of the outer roller 50b being guided by the bottom surface of the concave groove 51. It is possible to move linearly in the direction of the groove 51.

 In such a tripod type constant velocity universal joint, the forged parting line P is translated several millimeters from the center plane D so as not to overlap the tripod center plane D as shown in FIG. The direction of translation is the right side in FIG. 6B, but may be the opposite left side.

 As mentioned above, although it demonstrated per embodiment of this invention, this invention is not limited to the said embodiment, A various deformation | transformation is possible. For example, in FIGS. 5 to 8, only the form in which the forging parting line P is entirely translated is shown. However, as in FIG. 3C, only the root portion of the trunnion journal does not overlap the tripod center plane D. In other words, the forged parting line P is separated from the circumferential outermost line of the tripod so that it does not overlap with the circumferential outermost line of the tripod, and the remaining forged parting line P is overlapped with the tripod central plane D. You can leave it alone.

The tripod of the tripod type constant velocity universal joint which concerns on 1st Embodiment of this invention is shown, (A) is sectional drawing of a tripod, Comprising: The sectional view on the AA line of (C), (B) is (A ) Is an enlarged cross-sectional view taken along the line B-B in FIG. The longitudinal section of the tripod type constant velocity universal joint concerning a 1st embodiment of the present invention. The modification of the tripod of the tripod type constant velocity universal joint which concerns on 1st Embodiment is shown, (A) is sectional drawing of a tripod, Comprising: The sectional view on the AA line of (C), (B) is (A ) Is an enlarged cross-sectional view taken along the line B-B in FIG. The cross section of the tripod type constant velocity universal joint which concerns on 2nd Embodiment of this invention. The tripod of the tripod type constant velocity universal joint which concerns on 2nd Embodiment is shown, (A) is sectional drawing of a tripod, Comprising: A sectional view taken on the line AA of (C), (B) is B of (A). -B line arrow expanded sectional view, (C) is a partially cutaway side view of a tripod. (A) is a cross-sectional view of a tripod type constant velocity universal joint according to a third embodiment of the present invention, and (B) is a partially cutaway side view of the tripod of the joint. (A) is a cross-sectional view of a tripod type constant velocity universal joint according to a fourth embodiment of the present invention, and (B) is a partially cutaway side view of the tripod of the joint. (A) is a cross-sectional view of a tripod type constant velocity universal joint according to a fifth embodiment of the present invention, and (B) is a partially cutaway side view of the tripod of the joint. The perspective view of the conventional tripod type constant velocity universal joint. The cross-sectional view of the conventional tripod type constant velocity universal joint. (A) is sectional drawing of the conventional tripod, Comprising: The sectional view on the AA line of (C), (B) is the expanded sectional view on the BB line of (A), (C) is a tripod. Partial cutaway side view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tripod type constant velocity universal joint 2, 4 Rotating shaft 3 Housing 4 Rotating shaft 5 Tripod 6 Recessed groove 6a Arc-shaped guide surface 7 Boss 8 Journal 8a Journal 8b Journal 8c Journal 8d Journal 9 Roller cassette 9a Inner roller 9b Outer roller 9c Needle Roller 9d Retainer ring 19 Roller cassette 19a Inner roller 19b Outer roller 19c Needle roller 20 Flat surface 21 Outer flange 22 Concave groove 22a Guide surface 22b Guide shoulder 30 Roller 31 Circlip 32 Retainer ring 33 Needle roller 34 Concave groove 34a Guide surface 40 Roller 41 Cylindrical roller 42 Concave groove 42a Guide surface 50 Roller cassette 50a Inner roller 50b Outer roller 50c Needle roller 50d Retainer ring 51 Concave groove 51a Guide surface 52 Outer flange D Tripod center plane P Forged party Ngurain

Claims (2)

A hollow cylindrical housing that is fixed at the end of the first rotating shaft and that is formed at one end side in the axial direction and has a concave groove extending in the axial direction at a circumferentially equally divided position on the inner peripheral surface;
A tripod formed by forging integrally formed by a boss fixed to the end of the second rotating shaft and a trunnion journal protruding in a radial direction from a circumferentially divided position of the boss;
In a tripod type constant velocity universal joint having a roller fitted into the outer peripheral surface of the trunnion journal and accommodated in a groove in the housing and capable of rolling in the axial direction of the housing,
The tripod type constant velocity universal joint characterized in that the forged parting line of the tripod is separated from the outermost edge line so as not to overlap the outermost edge line in the circumferential direction of the tripod at least at the root portion of the trunnion journal.   The tripod forging parting line is generally translated from the outermost edge line to the joint axial direction so as not to overlap the circumferential outermost edge line of the tripod at the root portion of the trunnion journal. The tripod type constant velocity universal joint according to claim 1.

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