JPH0326335Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to an outer member of a constant velocity universal joint that is capable of relative displacement in the axial direction and is used in a rotational force transmission section of an automobile.

[Conventional technology]

As a constant velocity universal joint capable of relative displacement in the axial direction, a tripod type constant velocity universal joint as shown in FIGS. 1 and 2 is known. In the figure, 1 is an outer member that is cup-shaped with one end open and has a petal-shaped cross section.The base has an integral shaft part that projects outward, and the shaft part is equidistant on the inner circumference. 3 extending in the direction
It has a striped roller guide groove 2. Each roller guide groove 2 has a pair of opposing cylindrical track surfaces 2a.
and a track ceiling surface 2b connecting the large diameter sides of these track surfaces 2a. 3 is a shaft, and a trunnion 4 is fixed to a spline portion at the tip. The trunnion 4 has two trunnion shafts 5 extending radially from equidistant positions on the circumferential surface,
Each trunnion shaft 5 has a spherical roller 6 and a needle roller 9.
It is rotatably mounted via the In addition, 7,8
is a clip for fixing the trunnion 4. A constant velocity universal joint is constructed by inserting the spherical roller 6 of the shaft 3 into the roller guide groove 2 of the outer member 1.

In the constant velocity universal joint having the above structure, rotational force is transmitted between the shaft 3 and the outer member 1 at a constant speed by the engagement between the spherical roller 6 and the roller guide groove 2, and the spherical roller 6 Rolling in the axial direction along the track surface 2a of the roller guide groove 2 enables relative movement in the axial direction between the shaft 3 and the outer member 1,
Further, the rotation of the spherical roller 6 between the track surfaces 2a of the roller guide groove 2 allows the shaft 3 and the outer member 1 to assume an operating angle.

Normally, the operating angle of this type of constant velocity universal joint is determined by the diameter of the periphery of the opening end of the outer member 1. That is, for bending at the portion that coincides with the roller guide groove 2, a sufficient operating angle can be obtained because the peripheral edge of the opening end of the roller guide groove 2 has a relatively large diameter. The bending at the reduced-diameter connecting portion 1a cannot provide a large operating angle because the diameter of the opening end periphery is small. Therefore, a chamfer 1b is provided at the open end of the diameter-reduced connecting portion 1a to obtain as large an operating angle as possible.

In addition, in order to increase the fatigue strength of the outer member 1 and at the same time improve the wear resistance of the track surface 2a of the roller guide groove 2 that contacts the spherical roller 6, the entire inner surface of the track surface 2a is surface hardened, and the outer member 1 is hardened. The height of the inner surface of the member 1 is increased.

[The problem that the idea aims to solve]

However, as shown in FIG. 3, the track ceiling portion 2b' of the roller guide groove 2 of the outer member 1 has a particularly thin wall thickness because the boot band tightening groove is formed on its outer surface. , outer member 1
When surface hardening was applied to the entire inner surface of the track ceiling part 2b', the track ceiling part 2b' became rather brittle, resulting in the drawback that cracks could form in this part. In particular, cracks tend to occur from the periphery of the opening end.

In addition, if a chamfer is provided at the open end of the diameter-reducing joint, the strength of this part will be reduced, so when the spherical roller slides to the open end of the track guide groove, there is a risk of damage due to large loads. There is. In particular, when transmitting rotational torque at a large operating angle, a large load is applied to the open end. Therefore, the effective guide range of the roller guide groove must be limited so that the spherical roller does not reach the open end.

Therefore, the purpose of this invention is to improve the durability of the outer member of the constant velocity universal joint, and to enable a large operating angle without restricting the slidable range of the spherical roller. To this end, it is necessary to increase the breaking strength of the truck ceiling and to reinforce the opening end of the diameter-reduced connection.

[Means to solve the problem]

This invention has three roller guide grooves on the inner surface, and each roller guide groove is formed by a pair of track surfaces and a track ceiling surface that connects them. In the outer member of a constant velocity universal joint having a petal-shaped cross section, the track surface and the diameter-reducing connection are provided with a chamfer at the open end of the diameter-reducing connection to allow a large operating angle. The problem was solved by forming a hardened layer on the opening end of the track ceiling surface, and making at least the opening end of the truck ceiling surface and the inner surface of the diameter-reduced connection part a non-hardened part.

[Effect]

The surface other than the track surface and the opening of the diameter-reduced connecting portion, especially at least the opening end of the track ceiling surface, becomes a burn-out portion, increasing the breaking strength. In addition, by forming a hardened layer on the open end of the diameter-reducing connection part, this part is actively reinforced, so that it can withstand a large load even when the spherical roller moves to the open end of the track guide groove. become bearable.

〔Example〕

Embodiments of this invention will be described below with reference to FIGS. 4 to 9.

FIG. 4 shows the hardening pattern of the open end of the outer member 21, and FIG. 5 shows the hardening pattern of the inner surface of the intermediate portion of the outer member 21. Further, FIG. 6 shows a pattern of the hardened layer formed on the inner surface of the outer member 21. As shown in FIG.

The shape of the outer member 21 is similar to the conventional one shown in FIGS. 1 to 3, and 22 in the figure is the outer member 21.
Three roller guide grooves extending in the axial direction are formed at equal circumferential positions on the inner surface of the roller guide groove 22.
22b is a track ceiling surface of the roller guide groove, 21a is a diameter-reduced connecting portion connecting the small diameter side of the roller guide groove 22, and 21b is a chamfer formed at the open end of the diameter-reducing connecting portion 21a. As shown in FIGS. 4 to 6, the hardened layer A is applied to the entire area of each track surface 22a and the chamfer 21b of the diameter-reduced connecting portion 21a.
The other portions, that is, the inner surfaces of the track ceiling surface 22b and the diameter-reduced connecting portion 21a, are formed as burn-out portions. Depending on the method of surface hardening, for example, as shown in FIG.
Only a portion of the hardened layer is placed on the back side of the outer member 21 of 2b.
A′ may be formed. This hardened layer A′ is
It is formed in a small portion of the track ceiling surface 22b by a hairpin-shaped heating coil of a high-frequency heating device, which will be described later, used when surface hardening the track surface 22a. This hardened layer is the strongest part at the back of the truck ceiling 22b'
The presence of A' prevents cracks from entering the track ceiling portion 22b'.

7 to 9 show an example of a high frequency heating device 30 used to form the above-mentioned predetermined hardened layer A on the outer member 21 of the constant velocity universal joint. In the figure, reference numeral 31 denotes an induction coil installed vertically to be inserted into each roller guide groove 22 of the outer member 21. A conductive metal tube is bent into three hairpin shapes and divided into three equal positions. The coil leads 32 are connected to both ends of the coil leads 32, and are supported by a coil holder 33. 34 in FIG. 9 is the roller guide groove 22
A non-conductive ferrite core is attached to the induction coil 31 in order to harden only the track surface 22a of the induction coil 31. and are fixed together via mounting screws 35 and a baking plate 36 for mounting. Reference numeral 37 denotes a socket ring having the same petal shape as the inner diameter opening end of the outer member 21 and having a window hole 38 with a slightly smaller diameter.The socket ring 37 is placed on the coil holder 33, and each induction coil 31 is passed through the window hole 38. I have let you. 39 is a cooling nozzle disposed at the center of the window hole 38 of the outlet ring 37, and 40 is an outer peripheral jacket.

When hardening the outer member 21 of the constant velocity universal joint using the high frequency heating device 30, first,
The induction coil 31 is housed in each roller guide groove 22 of the outer member 21, placed on the outlet ring 37, and positioned and supported from above in the axial direction by a collector chuck (not shown). Next, when the coil lead 32 is energized to flow current through each induction coil 31, an induced current is generated in the outer member 21, and the outer member 21
The track surface 22a of the roller guide groove 22 and the open end of the diameter-reducing connection are heated by induction. The outer periphery of the induction heating part of the outer member 21 is constantly cooled by the outer jacket 40, and at the same time as heating is completed, cooling water is injected from the cooling nozzle 39 to cool the heating part, that is, the track surface 22a of the roller guide groove 22 and the diameter-reduced connection part. By cooling the open end of 21a, a predetermined hardened layer A is formed.

[Effect of idea]

This invention does not form a hardened layer on the inner surface of the outer member of the constant velocity universal joint, at least on the open end of the track ceiling surface and on the inner surface of the diameter-reduced connecting portion.
Since a hardened layer is formed on the track surface and the opening end of the diameter-reduced joint, the track ceiling surface, which is thin and weak in strength, becomes a burnout area and improves fracture strength.
Cracks are less likely to occur when transmitting torque while maintaining the operating angle. In addition, by forming a hardened layer on the open end of the diameter-reducing joint, this area is actively reinforced, so even if a large chamfer exists, the roller guide groove will extend over its entire length including the open end. The roller guide function can be effectively performed across the range. Therefore, according to this invention, it is possible to obtain an outer member of a constant velocity universal joint that can have a large operating angle without restricting the slidable range and is highly durable.

[Brief explanation of drawings]

Figures 1 and 2 are a cross-sectional view and a longitudinal cross-sectional view of a tripod type constant velocity universal joint, Figure 3 is a perspective view of the outer member of the tripod type constant velocity universal joint, and Figures 4 and 5 are external views. 6 is a developed view of the inner surface of the outer member, and FIGS. 7 to 9 are longitudinal sectional views, a plan view, and a cross sectional view of main parts showing an example of a high-frequency heating device. It is a diagram. 21: Outer member, 22: Roller guide groove, 21
a: Diameter reduction connection part, 21b: Chainhua, 22a:
Track surface, 22b: track ceiling surface, A: hardened layer.

Claims (1)

[Scope of utility model registration request] It has three roller guide grooves on the inner surface, each roller guide groove is formed by a pair of track surfaces and a track ceiling surface connecting them, and the roller guide grooves are connected by a diameter-reduced connecting part. In the outer member of a constant velocity universal joint having a shape, the opening end of the diameter-reducing joint is provided with a chamfer so that a large operating angle can be obtained, wherein the track surface and the opening end of the diameter-reducing joint are 1. An outer member of a constant velocity universal joint, characterized in that a hardened layer is formed on the outer member of the constant velocity universal joint, and at least the open end of the track ceiling surface and the inner surface of the diameter-reduced connecting part are non-hardened parts.