JP4943276B2 - Tripod type constant velocity universal joint - Google Patents

Description

  The present invention relates to a tripod type constant velocity universal joint, and can be used for power transmission devices of automobiles and various industrial machines.

  The tripod type constant velocity universal joint is a kind of a sliding type constant velocity universal joint capable of not only angular displacement but also axial displacement. As shown in FIG. 10, an outer ring 10 as an outer joint member and an inner joint member as A trunnion 20 and a roller 30 as a torque transmission element are main components (see Patent Document 1). The outer ring 10 is formed with a track groove 14 extending in the axial direction at a circumferentially equally divided position on the inner periphery, and the trunnion 20 is formed with a leg shaft 26 protruding radially at a circumferentially equally divided position. It is. A roller 30 is rotatably attached to each leg shaft 26 via needle rollers 32. The roller 30 is accommodated in the track groove 14 of the outer ring 10.

The needle roller 32 is interposed between the leg shaft 26 and the roller 30 in the state of a full roller. At the inner washer 38. The inner washer 38 is seated on a step formed at the boundary between the root of the leg shaft 26 and the boss 22 of the trunnion 20.
Since the retainer 34 is restricted from moving in the axial direction by a retaining ring 36 attached to the ring groove 28 of the leg shaft 26, the needle roller 32 is also restricted from moving in the axial direction. That is, with respect to the movement toward the base side of the leg shaft 26, the position of the base portion of the leg shaft 26 and the inner washer 38 are regulated, and the movement toward the tip side of the leg shaft 26 is regulated with the retainer 34, that is, withdrawn. Stop it. The retainer 34 includes a disk portion 34 a extending in the radial direction of the leg shaft 26 and a cylindrical portion 34 b extending in the axial direction of the leg shaft 26. The outer diameter of the cylindrical portion 34 b of the retainer 34 is smaller than the inner diameter of the roller 30, and is larger than the inner diameter of the roller 30 at the outer end 34 c when viewed in the radial direction of the trunnion 20. Therefore, the roller 30 can move over a certain range in the axial direction of the leg shaft 26.
Japanese Patent No. 3615987

As described above, the conventional tripod type constant velocity universal joint prevents the needle rollers 32 from popping out by the retainer 34 and the retaining ring 36 attached to the distal end side of the leg shaft 26. In the state where the joint takes an operating angle, the leg shaft 26 moves in the axial direction relative to the roller 30 as the joint rotates, and thus the axial position of the needle roller 32 needs to be regulated. However, in the position restriction by the retainer 34 and the retaining ring 36, in addition to the cost of these parts, a processing cost for forming the ring groove 28 in the leg shaft 22 is required, so that the cost is generally increased.
In addition, as described above, the roller 30 moves in the axial direction of the leg shaft 26 as the joint rotates, and the amount of movement increases as the operating angle increases, so that uneven wear of the leg shaft 26 is prevented. Therefore, the position of the needle roller 32 with respect to the roller guide surface 16 needs to be set to be suitable for the normal operating angle.

  Accordingly, an object of the present invention is to prevent uneven wear by restricting the position of the needle roller only by the leg shaft without using a retainer and a retaining ring.

The tripod type constant velocity universal joint according to the present invention includes an outer ring in which track grooves extending in the axial direction are formed at circumferentially divided positions on the inner circumference, and roller guide surfaces are formed on both side walls of each track groove; A trunnion having a leg shaft projecting radially from a bisector of the direction, and a rotatably supported by the leg shaft, and can move in the track groove direction along the roller guide surface while moving along the roller guide surface. such a roller, in the tripod type constant velocity joint having a plurality of needle rollers that is interposed between the roller and the trunnion, on the outer peripheral surface of the leg axis, for housing the needle rollers The track groove having a bottom surface and both side walls is formed, and the width center of the track groove is aligned with the width center of the roller guide surface.

According to this invention, since the needle rollers are accommodated in the raceway grooves on the outer peripheral surface of the leg shaft, both side walls of the raceway grooves serve as axial position restricting portions of the needle rollers, and the joint takes an operating angle. Even if the leg shaft moves relative to the roller, the needle roller can be prevented from popping out.
Furthermore, by making the width center of the raceway groove coincide with the width center of the roller guide surface, especially when the normal operating angle is small (for example, 6 ° or less), the joint is rotating and is approximately near the center in the width direction of the raceway groove. A load is applied, and uneven wear of the leg shaft can be prevented.

Embodiments of the present invention will be described below with reference to the drawings.
First, the basic structure of a tripod constant velocity universal joint will be described with reference to FIG. The tripod type constant velocity universal joint includes an outer ring 10 as an outer joint member, a trunnion 20 as an inner joint member, and a roller 30 as a torque transmission element as main components.

  The outer ring 10 includes a mouse portion 12 and a stem portion 18 (FIG. 10A), and a spline (or serration, hereinafter the same) shaft portion of the stem portion transmits torque to one of the two shafts to be connected. It is designed to connect as possible. The mouse portion 12 is cup-shaped, and a track groove 14 extending in the axial direction is formed at a position of the inner circumference in the three-way division (FIG. 10B).

  The trunnion 20 is composed of a boss portion 22 and a leg shaft 26, and is connected to the other of the two shafts to be coupled by a spline hole 24 formed in the axial center portion of the boss portion 22 so that torque can be transmitted. Yes. The leg shaft 26 protrudes in the radial direction from the circumferentially divided position of the boss portion 22. A roller 30 is rotatably supported on each leg shaft 26 via needle rollers 32 as rolling elements.

  The roller 30 is accommodated in the track groove 14 of the outer ring 10 and can move in the axial direction of the outer ring 10. When the torque is transmitted with the joint at an operating angle, the roller 30 reciprocates in the axial direction of the outer ring 10 while rotating around the leg shaft 26. Side walls on both sides of the track groove 14 serve as guide surfaces 16 when the roller 30 rolls. The roller guide surface 16 has a concave arc shape or a Gothic arch shape when viewed in a cross section (FIG. 10B), and the outer peripheral surface of the roller 30 has an arc shape.

  Here, the embodiment will be described with reference to FIG. 1. Each leg shaft 26 has a cylindrical shape, and a raceway groove 40 is formed on the outer peripheral surface. The track groove 40 has a bottom surface 42 and both side walls 44 and 46. The needle rollers 32 are arranged in a full roller state in the raceway groove 40 of the leg shaft 26 and roll on the bottom surface 42 of the raceway groove 40. The bottom surface 42 of the raceway groove 40 becomes the inner raceway surface of the needle roller 32, and the inner peripheral surface of the roller 30 becomes the outer raceway surface of the needle roller 32. Both side walls 44 and 46 of the raceway groove 40 interfere with the end face of the needle roller 32 to restrict the position of the needle roller 32 in the axial direction.

  As shown by a one-dot chain line in FIG. 1, the width center of the raceway groove 40 and the width center of the roller guide surface 16 are matched. 1A shows an example in which a step portion 25 (see FIG. 2) is formed at the base of the leg shaft 26, and FIG. 1B shows an example in which such a step portion is not provided. Also in the embodiment described below, both the one having the step portion 25 at the base of the leg shaft 26 and the one having no step portion 25 are possible.

  When the torque is transmitted with the tripod constant velocity universal joint at an operating angle, the roller 30 reciprocates in the axial direction of the outer ring 10 in the track groove 14, and during that time, between the leg shaft 26 and the roller 30. Repeat relative axial movement. The relative movement is absorbed by the slip between the needle roller 32 and the inner peripheral surface of the roller 30. The amount of relative movement is greater in the radially inward movement than in the radially outward movement of the outer ring 10. This amount of movement increases in proportion to the operating angle. When the normal operating angle is large, it is effective to offset the width center of the raceway groove 40 toward the tip end side of the leg shaft 26 with respect to the width center of the roller guide surface in accordance with the amount of movement. However, when the joint operating angle is relatively small, for example, 6 ° or less, the moving amount is extremely small. Therefore, in this case, it is possible to prevent uneven wear of the raceway groove 40 by matching the width center of the raceway groove 40 and the width center of the roller guide surface 16 as shown in FIG.

  A semi-solid lubricant or a solid lubricant is applied to help the needle rollers 32 be aligned and held in the raceway groove 40. In FIG. 1C showing the tripod kit with the roller 30 removed, the hatched portion represents the lubricant. Semi-solid lubricants or solid lubricants have a consistency of 0, 1 or 2. The consistency indicates the hardness of the lubricant, and is classified into 9 levels from the following No. 000 to No. 6 according to JIS K 2220 5.3. No. 000: Semi-fluid, No. 00: Semi-fluid, No. 0: Soft, No. 1: Soft, No. 2: Slightly soft, No. 3: Normal, No. 4: Slightly hard, No. 5: Hard, No. 6: Solid . In order to assist the needle rollers being aligned and held in the raceway groove, the consistency of the lubricant is preferably No. 1, No. 1 or No. 2.

  Specific examples of the semi-solid lubricant or the solid lubricant include grease, foamed resin, and plastic grease. As is well known, grease is a semi-solid or solid form obtained by dispersing a thickener in a base oil. The foamed resin is a foamed PET lubricant or the like. For example, 1 part by weight of PET foamed lubricant is stirred with 99 parts by weight of distilled water and foamed to form rigid cells. The plastic grease is, for example, solidified by heating a mixture of 1 to 95% by weight of polyethylene, preferably 30% by weight or more, and 99 to 5% by weight of soap or non-soap-enriched lubricating grease. Some plastic greases are marketed under the name "Polyrub" (registered trademark).

  As shown in FIG. 2, the depth d of the raceway groove 40 of the leg shaft 26 is preferably 10% or more and 50% or less of the diameter of the needle roller 32. When the depth d of the raceway groove 40 is less than 10% of the diameter of the needle roller 32, the contact area between the side walls 44 and 46 of the raceway groove 40 and the needle roller 32 is too small, and the axial direction of the needle roller 32 is small. It is not enough to control the position. If the depth d of the raceway groove 40 exceeds 50% of the diameter of the needle roller 32, the contact area between the side walls 44, 46 of the raceway groove 40 and the end face of the needle roller 32 becomes too large, and friction loss and heat generation occur. Become prominent.

  The leg shaft 26 of the trunnion 20 may be a forged skin or a cold forged skin except for the raceway groove 40. The leg shaft 26 is required to have a dimensional accuracy in the raceway groove 40, and other than that, a very high dimensional accuracy is not required. Therefore, the manufacturing cost of the tripod type constant velocity universal joint can be reduced by leaving the surface of the leg shaft other than the raceway groove 40 as the forged skin or the cold forged skin.

Alternatively, the leg shaft 26 of the trunnion 20 including the raceway groove 40 may be subjected to hardened steel cutting or overall grinding. In this case, as shown in FIG. 3, the needle roller 32 is restricted in the axial direction by applying a rounded corner portion of the needle roller 32 to the side wall 44 of the raceway groove 40 .

  In the embodiment shown in FIG. 4, both side walls 44 and 46 of the raceway groove 40 of the leg shaft 26 are inclined in a tapered shape. By widening the side walls 44 and 46 in a tapered shape, it is possible to prevent the vicinity of the center of the end face of the needle roller 32 from coming into contact with the side walls 44 and 46 as shown in FIG. Thereby, the skew of the needle roller 32 can be prevented and the rotational behavior of the needle roller 32 can be stabilized.

  In the embodiment shown in FIG. 5, crowning having a convex arcuate cross section is formed on the bottom surface 42 of the raceway groove 40 of the leg shaft 26 and the inner peripheral surface of the roller 30. Thereby, the low operating angle side NVH characteristic can be improved by allowing the roller 30 to swing freely on the joint lower operating angle side. The crowning may be formed only on one of the raceway groove 28 of the leg shaft 26 or the inner peripheral surface of the roller 30.

  In the embodiment shown in FIG. 6, a cap 50 is attached to the tip of the leg shaft 26. The cap 50 includes a shaft portion 52 and a disk portion 54 and is used for preventing the roller 30 from coming off, so that the outer diameter of the disk portion 54 is larger than the inner diameter of the roller 30. Various fixing structures for the cap 50 are conceivable. For example, the shaft portion 52 may be fitted into a hole 48 formed in the distal end surface of the leg shaft 26. Further, the shaft portion 52 may be press-fitted into the hole 48. Alternatively, a structure may be adopted in which a screw is cut into the shaft portion 52 and a female screw is cut into the hole 48 and fastened with a screw. The cap 50 is made of, for example, steel or resin, and other materials satisfying a predetermined strength can be used.

  In the embodiment shown in FIG. 7, a washer 56 with a slit is attached to the tip end side of the raceway groove 40 of the leg shaft 26 to prevent the needle roller 32 and the roller 30 from coming off. In this case, the washer 56 is fitted into the raceway groove 40 in a state where the diameter is increased by utilizing elastic deformation. The outer diameter of the washer 56 is larger than the circumscribed circle diameter of the needle rollers 32 arranged in the raceway groove 40. Although various shapes of the washer 56 can be adopted, FIG. 7A shows an example in which the outer diameter side is slightly extended and the outer diameter side is inclined toward the distal end side of the leg shaft, and FIG. 7B is a short extension in the radial direction. An example is shown.

  In the embodiment shown in FIG. 8, a crown having a concave arc shape in cross section is formed on the bottom surface 42 of the raceway groove 40 of the leg shaft 26, and a crowning having a convex arc shape in cross section is formed on the inner peripheral surface of the roller 30. The degree of crowning (the radius of curvature) is preferably such that the needle rollers 32 are in line contact with the outer peripheral surface of the leg shaft 26, that is, the bottom surface 42 of the raceway groove 40 on the lower operating angle side of the joint operating angle. Thereby, on the joint low operating angle side, the skew of the needle rollers 32 can be actively induced to reduce the surface pressure and increase the life. The crowning may be formed only on the bottom surface 42 of the raceway groove 40 of the leg shaft 26 without forming the crowning on the inner peripheral surface of the roller 30.

  In the embodiment shown in FIG. 9, the width of the raceway groove 40 of the leg shaft 26, that is, the distance between both side walls 44, 46 of the raceway groove 40 is set at both ends of the needle roller 32 with the needle roller 32 accommodated in the raceway groove 40. The sum (a + b) of the axial clearances a and b existing between the side wall 44 and 46 of the raceway groove 40 is shifted in the radial direction of the outer ring 10 at the normal operating angle of the joint (the axis of the leg shaft). It is set to be larger than the maximum shift amount when moving in the direction). In this case, the amount that the needle roller 32 can move in the axial direction is larger than the maximum shift amount when the leg shaft 26 shifts with respect to the roller 30 at the common operating angle of the joint. Therefore, the number of times the end of the needle roller 32 contacts the side walls 44 and 46 of the raceway groove 40 is greatly reduced, and the rotational behavior of the needle roller 32 is stabilized. Contributes to the improvement of NVH performance.

(A) and (B) are the partial cross-sectional views of the tripod type constant velocity universal joint which shows an Example, (C) is the elements on larger scale of the tripod kit of the state which removed the roller. It is the elements on larger scale of a leg axis. It is the elements on larger scale of a leg axis. (A) is the elements on larger scale of a leg axis, (B) is the B section expanded sectional view of Drawing 4 (A). It is a partial expanded sectional view of a tripod kit. It is a partial expanded sectional view of a tripod kit. (A) (B) is sectional drawing of the tripod kit which shows the Example which used the washer with the slit for retaining. It is a fragmentary sectional view of the tripod kit which shows the Example which formed crowning. It is the elements on larger scale of the leg axis which has arranged the needle roller in the raceway groove. The conventional tripod type constant velocity universal joint is shown, (A) is a longitudinal cross-sectional view, (B) is a cross-sectional view, (C) is the elements on larger scale of FIG. 10 (B).

Explanation of symbols

10 Outer ring (outer joint member)
12 Mouse part 14 Inner peripheral surface 16 Track groove 18 Stem part 20 Trunnion (inner joint member)
22 Boss portion 24 Spline hole 25 Step portion 26 Leg shaft 40 Track groove 42 Bottom surface 44 Side wall 46 Side wall 48 Hole 30 Roller (torque transmission element)
32 Needle rollers (rolling elements)
50 Cap 52 Shaft portion 54 Disc portion 56 Washer with slit

Claims (8)

A track groove extending in the axial direction is formed at a circumferentially equally divided position on the inner periphery, and an outer ring having roller guide surfaces formed on both side walls of each track groove, and projecting in a radial direction from the circumferentially equally divided position. A trunnion having a leg shaft, a roller rotatably supported by the leg shaft, and capable of moving along the roller guide surface in the track groove and moving in the outer ring axial direction; the leg shaft and the roller; in the tripod type constant velocity joint having a plurality of needle rollers that is interposed between, formed on the outer peripheral surface of the leg axis, for housing the needle rollers, the track groove having a bottom and side walls And a tripod type constant velocity universal joint in which the width center of the raceway groove and the width center of the roller guide surface are made to coincide.   The tripod constant velocity universal joint according to claim 1, wherein a surface of the trunnion excluding the raceway groove portion is forged skin.   The tripod type constant velocity universal joint according to claim 1, wherein the leg shaft includes a hardened steel cutting process or a general grinding process including the raceway groove.   The tripod type constant velocity universal joint according to claim 1, wherein both side walls of the raceway groove are tapered.   The tripod type constant velocity universal joint according to claim 1, wherein a crowning having a convex arcuate cross section is formed on the bottom surface of the raceway groove, the inner peripheral surface of the roller, or both.   The tripod type constant velocity universal joint according to claim 1, wherein a cap having a diameter larger than the inner diameter of the roller is attached to the leg shaft.   The tripod type constant velocity universal joint according to claim 1, wherein a crowning having a concave arc shape in cross section is formed on a bottom surface of the raceway groove.   The width of the raceway groove is the sum of the axial clearances existing between both ends of the needle rollers and both side walls of the raceway groove. The leg shaft is shifted in the radial direction of the outer ring at the normal operating angle of the joint. The tripod type constant velocity universal joint of Claim 1 set so that it might become larger than the maximum shift amount at the time of carrying out.

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