JP2008208858A - Tripod constant velocity joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small configuration of an outer member of a tripod constant velocity joint to which a resin boot can be easily assembled. <P>SOLUTION: Three track grooves 22a to 22c separated from each other by 120° are formed on the inner wall surface of a bottomed cylindrical part 12 of the outer member 14. Each of the track grooves 22a-22c comprises a bottom wall 24 formed in the direction extending along the outer peripheral surface of the bottomed cylindrical part 12 and two side walls 26, 26 raised in substantially vertical direction from the bottomed wall 24 and opposed to each other. Hardened layers 28 having a thickness of 0.8-3 mm are formed near the side walls 26, 26 by induction hardening. Since induction hardening is not applied to the bottom wall 24, no hardened layer 28 is formed near the bottom wall 24. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to, for example, a constant velocity joint that connects one transmission shaft and the other transmission shaft in a driving force transmission unit of an automobile.

  The automobile travels as the rotational power generated by various engines such as an internal combustion engine and a motor is transmitted from the differential gear to the hub via a plurality of joint structures, thereby rotating the tire.

  The joint structure includes a transmission shaft such as a half shaft or a spline shaft, and a constant velocity joint. That is, for example, the differential gear and the spline shaft are connected via a so-called inboard side constant velocity joint, and further, the spline shaft and the hub are connected via a so-called outboard side constant velocity joint. And the connection location of these constant velocity joints and various transmission shafts is covered with a joint boot.

  As the inboard side constant velocity joint, a triport type constant velocity joint is usually adopted. Here, the triport type constant velocity joint includes an outer member having a shaft portion and a cylindrical portion, and a shaft of a differential gear is connected to the shaft portion, and the tip of the spline shaft is fitted to the cylindrical portion. The joined inner member is inserted. A plurality of track grooves spaced apart from each other at equal intervals are formed on the inner peripheral wall of the cylindrical portion. Each track groove is composed of a bottom wall and two side walls rising substantially vertically from the bottom wall.

  One inner member has an annular portion and a plurality of trunnions protruding from the outer peripheral wall of the annular portion, and the trunnions face each of the track grooves. Further, a substantially annular roller is rotatably fitted to each trunnion, and the differential gear and the spline shaft are connected by inserting the roller into each of the track grooves. The side wall of the roller is in sliding contact with the side wall of the track groove, while the bottom wall is separated from the bottom surface of the roller by a predetermined distance.

  By the way, from the viewpoint of global environmental protection and resource protection in recent years, automobiles are required to reduce nitrogen oxide, sulfur oxide, and hydrocarbons contained in exhaust gas and to improve fuel efficiency. As one of measures to meet this demand, it is considered to operate the internal combustion engine at a high temperature.

  In this case, inevitably, the joint boot that covers the inboard side constant velocity joint close to the internal combustion engine must be resistant to deterioration even at high temperatures. Conventionally, rubber is generally used as a material for joint boots, but in recent years, resins are being employed to ensure durability at high temperatures (see, for example, Patent Document 1).

JP 2004-338772 A

  As can be understood from the above, the side peripheral wall of the roller is in sliding contact with the side wall of the track groove provided in the cylindrical portion of the outer member. In order to avoid wear of the side wall of the track groove due to this sliding contact, it is usual to increase the hardness by subjecting the track groove to induction hardening or the like.

  Incidentally, the resin boot is less flexible than the rubber boot, and it is somewhat difficult to insert the cylindrical portion of the outer member. In order to avoid this inconvenience, it is necessary to reduce the wall thickness (distance from the bottom wall of the track groove to the outer peripheral wall) of the opening of the cylindrical portion, thereby making it easy to fit the resin boot. As will be recalled, in this case, when induction hardening is performed on the track groove of the cylindrical portion, the opening end of the cylindrical portion is expanded due to thermal stress.

  Expansion of the opening end can be avoided by increasing the wall thickness. However, in this case, it is not only more difficult to assemble the resin boot, but also the outer diameter of the cylindrical portion is increased and the size is increased. When such a situation occurs, it causes the weight of the inboard side constant velocity joint to increase, and the raw material cost increases as the size increases. Moreover, the layout of the engine room is limited.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a constant velocity joint including an outer member that can be easily assembled with a resin boot while being small in size.

In order to achieve the above object, a constant velocity joint according to the present invention is a cylinder provided with a shaft portion connected to the first transmission shaft and a plurality of track grooves extending along the axial direction on the inner wall. An outer member having a shape part;
An inner member having an annular portion fitted to the second transmission shaft inserted into the cylindrical portion, and a plurality of trunnions bulging from the annular portion toward each of the track grooves;
A plurality of rolling members externally fitted to each of the trunnions and slidably engaged with each of the track grooves;
Comprising
The track groove has a bottom wall and a side wall with which the rolling member slides,
The thickness of the hardened layer on the bottom wall is 0 to 2 mm, and the thickness of the hardened layer on the side wall is within a range of 0.8 to 3 mm and larger than the thickness of the hardened layer on the bottom wall. And That is, in the present invention, even when the hardened layer is not provided or provided on the bottom wall of the track groove, the thickness is 2 mm at the maximum and is compared with the thickness of the hardened layer on the side wall. And set small.

  By setting the thicknesses of the hardened layers on the bottom wall and the side wall in this way, it is possible to avoid as much as possible that thermal stress remains on the bottom wall. For this reason, even when the thickness from the bottom wall to the outer peripheral wall is small, it is possible to suppress distortion of the meat from the bottom wall to the outer peripheral wall. Eventually, it is possible to prevent the opening end of the cylindrical portion from expanding.

  Therefore, since the dimension of the opening end before and after the heat treatment on the side wall is substantially unchanged, even when a resin boot is used as the joint boot, the opening end of the tubular portion is used as the joint boot. Can be inserted easily. That is, it is possible to easily assemble the resin boot while keeping the cylindrical portion small.

  According to the present invention, the thickness of the hardened layer on the bottom wall and side wall of the track groove is set within a predetermined range, and the thickness of the hardened layer on the side wall is made larger than the thickness of the hardened layer on the bottom wall. Therefore, it is possible to avoid the thermal stress remaining on the bottom wall as much as possible. Thereby, even if it is an outer member with a small thickness from a bottom wall to an outer peripheral wall, in other words, even if it is a small-shaped outer member, it can suppress that the opening end part expands, and, as a result, a coupling Even when a resin boot is used, the outer member can be easily assembled to the joint boot.

  Preferred embodiments of the constant velocity joint according to the present invention will be described below in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic perspective view of a main part of a joint structure in which a tripart type constant velocity joint 10 according to the present embodiment is incorporated, and FIG. 2 is a partially cutaway side view thereof. This tripod type constant velocity joint 10 is fitted to one end of a second transmission shaft 16 and an outer member 14 having a shaft portion 11 and a bottomed cylindrical portion 12 connected to a first transmission shaft (not shown). A spider 18 (see FIG. 2) as an inner member inserted into the inside of the bottom cylindrical portion 12 is covered with a joint boot 20 from the end of the outer member 14 to the second transmission shaft 16. It has been broken. A grease composition is enclosed in the joint boot 20.

  On the inner wall surface of the bottomed cylindrical portion 12 of the outer member 14, as shown in FIGS. 3 and 4, three track grooves extending along the axial direction of the outer member 14 and spaced apart from each other by 120 ° 22a-22c are formed. These track grooves 22a to 22c are provided with a bottom wall 24 provided in a direction extending along the outer peripheral surface of the bottomed cylindrical portion 12, and two side walls that rise substantially vertically from the bottom wall 24 and face each other. 26.

  In FIG. 4, reference numeral 28 indicates a hardened hardened layer provided on the side wall 26 of the track grooves 22a to 22c. As will be described later, the hardened hardening layer 28 is formed by induction hardening, and the thickness thereof is in the range of 0.8 to 3 mm.

  On the other hand, no hardened hardening layer 28 is formed in the vicinity of the bottom wall 24. In other words, the bottom wall 24 is not induction hardened. For this reason, no thermal stress remains in the vicinity of the bottom wall 24.

  The spider 18 connected to the distal end portion of the second transmission shaft 16 is inserted into the hollow interior of the bottomed tubular portion 12 (see FIGS. 2 and 3). As shown in FIG. 4, the spider 18 is integrally formed with three trunnions 30 a to 30 c that bulge from the annular portion 29 toward the track grooves 22 a to 22 c and are 120 ° apart from each other. ing.

  Rolling mechanisms 32 are fitted on the side walls of the trunnions 30a to 30c, respectively. Each rolling mechanism 32 includes a holder 34 and a roller 36 as a rolling member, and a plurality of needle bearings 38 are interposed between the holder 34 and the roller 36. The needle bearings 38 are formed in a cylindrical shape having substantially the same dimensions.

  As shown in FIG. 5, the holder 34 is a substantially cylindrical body, and a flange portion 40 protruding outward in the diameter direction is provided on the lower end surface thereof. Further, an annular groove 44 is provided on the side peripheral wall of the equal diameter portion 42, and an Ω-shaped ohmic band 46 is fitted in the annular groove 44. That is, the rolling mechanism 32 is configured so that the roller 36 holding the needle bearing 38 via wax or wax is passed through the constant diameter portion 42 of the holder 34 and blocked by the flange portion 40. The ring body 48 covering up to a part of the upper end surface of the holder 34 is positioned by the ohmic band 46, and further, the ohmic band 46 is fitted into the annular groove 44.

  The inner peripheral surface of the equal-diameter portion 42 of the holder 34 is formed in a straight line, while the side wall portions of the trunnions 30a to 30c are curved (see FIG. 4). For this reason, the trunnions 30a to 30c are slidable along the arrow A direction in FIG. 4, that is, along the axial direction of the holder 34, and tiltable with respect to the holder 34 in the arrow B direction at a predetermined angle. Further, the trunnions 30a to 30c are also rotatable in the direction of arrow C.

  The upper end portion of the holder 34 protrudes toward the bottom wall 24 as compared with the smooth tip surfaces of the trunnions 30a to 30c, and is positioned so that a slight clearance is generated between the holder 34 and the bottom wall 24.

  The roller 36 is fitted on the outer peripheral portion of the equal diameter portion 42 of the holder 34 through the needle bearing 38. The curved side wall portion of the roller 36 is in sliding contact with the side wall 26 of the track grooves 22a to 22c, so that the roller 36 is guided by the side wall 26, and the arrow in FIG. 2 and FIG. As a result, the spider 18 and thus the second transmission shaft 16 are displaced relative to the bottomed tubular portion 12.

  The joint boot 20 (see FIG. 1) has a large diameter cylindrical portion 50 and a small diameter cylindrical portion 52 at each end, and a bellows portion 53 is interposed between the large diameter cylindrical portion 50 and the small diameter cylindrical portion 52. The large-diameter cylindrical portion 50 is fastened to one end portion of the outer member 14 via a tightening band 54, and the small-diameter cylindrical portion 52 is fastened to the second transmission shaft 16 via a tightening band 56 to be positioned and fixed. The Reference numerals 58 and 60 represent caulking portions formed by caulking these tightening bands 54 and 56.

  Among these, the outer member 14 provided with the hardened hardened layer 28 only in the vicinity of the side wall 26 can be manufactured using the high frequency induction coil 70 shown in FIG. That is, the high-frequency induction coil 70 has side wall heating portions 72 and 72 facing each side wall 26 and a retreating portion 74 bridged by the side wall heating portions 72 and 72. It is separated from the bottom wall 24 so as not to reach the wall 24.

  The high frequency induction coil 70 is inserted from the open end side of the bottomed cylindrical portion 12. When the high frequency induction coil 70 is energized in this state, heat is generated in the high frequency induction coil 70. As can be seen from FIG. 6, since the side wall heating parts 72, 72 are close to the side wall 26, the radiant heat from the side wall heating parts 72, 72 reaches the side walls 26, 26. Quenched and hardened layers 28 are formed in the vicinity. Of course, the high-frequency induction coil 70 is displaced along the depth direction of the track grooves 22 a to 22 c, that is, along the axial direction of the bottomed tubular portion 12, whereby the hardened and hardened layer 28 is provided over the entire side wall 26. .

  Since the high frequency induction coil 70 is also close to the inner peripheral wall of the bottomed cylindrical portion 12, a hardened hardening layer is also formed on the inner peripheral wall.

  On the other hand, the radiant heat from the receding portion 74 does not reach the bottom wall 24. For this reason, the hardening hardening layer 28 is not formed in the vicinity of the bottom wall 24.

  When configuring the joint structure, the second transmission shaft 16 is press-fitted into the small-diameter cylindrical portion 52 of the joint boot 20 (see FIG. 1), and further, at the tip of the second transmission shaft 16 exposed to the bellows portion 53 side. The spider 18 is attached. After the spider 18 is inserted into the outer member 14 together with the tip of the second transmission shaft 16 (see FIG. 2), the rollers 36 fitted to the trunnions 30a to 30c of the spider 18 are side walls of the track grooves 22a to 22c. 26 is slidably inserted.

  Next, the open end of the bottomed tubular portion 12 is inserted into the large-diameter tubular portion 50 of the joint boot 20. As described above, the hardened hardening layer 28 is not formed in the vicinity of each bottom wall 24 in the track grooves 22a to 22c of the bottomed cylindrical portion 12. That is, in the bottomed cylindrical portion 12, no thermal stress remains on the bottom wall 24 that is closest to the outer peripheral wall. For this reason, there is no distortion in the meat between the bottom wall 24 and the outer peripheral wall. Therefore, even when the distance (thickness) between the bottom wall 24 and the outer peripheral wall is small, the opening end portion Is prevented from spreading. Therefore, even if the joint boot 20 is made of a resin such as thermoplastic polyethylene (TPE), the open end portion of the bottomed tubular portion 12 can be easily inserted.

  Thus, according to the present embodiment, it is possible to greatly improve the assembling property of the tripod type constant velocity joint 10.

  Thereafter, the tightening band 54 is attached to the large-diameter cylindrical portion 50 covering the open end, and a part of the outer peripheral surface of the tightening band 54 is crimped so as to be sandwiched from the left and right directions by a crimping jig (not shown). Along with this caulking, a caulking portion 58 is formed to protrude from the outer peripheral surface of the tightening band 54. Similarly, the tightening band 56 attached to the small diameter cylindrical portion 52 is crimped to provide the crimping portion 60. Thus, the joint structure is completed.

  In the above-described embodiment, the case where the hardened hardened layer 28 is not formed on the bottom wall 24 has been described as an example. However, as shown in FIG. The quench hardened layer 80 may be formed on the bottom wall 24 by the radiation heat from the 74 thru | or side wall heating parts 72 and 72 reaching the bottom wall 24 or transferring heat from the side wall 26 to the bottom wall 24. . Even in such a case, if the quenching conditions are controlled so that the thickness of the quench-hardened layer 80 is 2 mm at the maximum and smaller than the thickness of the hardened-hardened layer 28, the size of the joint boot 20 is increased. It is possible to avoid the opening end portion of the bottomed tubular portion 12 from being expanded to the extent that it becomes difficult to insert the diameter tubular portion 50.

  Moreover, the hardening hardening layer 28 is not limited to what was formed by induction hardening, and may be formed by other hardening processes.

It is a principal part schematic perspective explanatory drawing of the joint structure in which the tripart type | mold constant velocity joint which concerns on this Embodiment was integrated. It is a partially cutaway side view of the tripod type constant velocity joint of FIG. It is a principal part schematic sectional drawing of the tripod type | mold constant velocity joint of FIG. 1 from which the boot was removed. It is a principal part enlarged front view of a bottomed cylindrical part which comprises the tripod type | mold constant velocity joint of FIG. It is a principal part schematic perspective view of the holder which comprises a rolling mechanism. It is a principal part enlarged front view which shows the high frequency induction coil for forming the hardening hardening layer in the vicinity of the side wall of the bottomed cylindrical part which comprises the tripod type | mold constant velocity joint of FIG. It is a principal part enlarged front view which shows the state which formed the hardening hardened layer in the vicinity of the side wall and bottom wall of a bottomed cylindrical part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Tripod type constant velocity joint 11 ... Shaft part 12 ... Bottomed cylindrical part 14 ... Outer member 16 ... 2nd transmission shaft 18 ... Spider 20 ... Joint boot 22a-22c ... Track groove 24 ... Bottom wall 26 ... Side wall 28 , 80 ... Hardened hardened layer 29 ... Annular portion 30a-30c ... Trunnion 32 ... Rolling mechanism 34 ... Holder 36 ... Roller 38 ... Needle bearing 50 ... Large diameter cylindrical portion 52 ... Small diameter cylindrical portion 53 ... Bellows portion 54, 56 ... Tightening band 70 ... high frequency induction coil 72 ... side wall heating part 74 ... receding part

Claims (1)

An outer member having a shaft portion connected to the first transmission shaft, and a cylindrical portion provided with a plurality of track grooves extending along the axial direction on the inner wall;
An inner member having an annular portion fitted to the second transmission shaft inserted into the cylindrical portion, and a plurality of trunnions bulging from the annular portion toward each of the track grooves;
A plurality of rolling members externally fitted to each of the trunnions and slidably engaged with each of the track grooves;
Comprising
The track groove has a bottom wall and a side wall with which the rolling member slides,
The thickness of the hardened layer on the bottom wall is 0 to 2 mm, and the thickness of the hardened layer on the side wall is within a range of 0.8 to 3 mm and larger than the thickness of the hardened layer on the bottom wall. Triport type constant velocity joint.

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