JP2001082498A - Constant velocity universal joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the manufacturing cost of a constant velocity universal joint. SOLUTION: The ringed cage 5 is provided with a spherical outside surface 5a to be touched and guided on the inside surface of an outside joint member, a spherical inside surface 5b to be touched and guided on the outside surface of an inside joint member and plural window type pockets 5c holding a torque transmission ball. The cage 5 is formed with austemper spherical graphite iron (ADI) or with sintered metal by metallic powder injection molding(MIM).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a constant velocity universal joint for transmitting rotational power at a constant speed even when there is an angular displacement or an axial displacement between two axes, and more particularly to an ATV (All Terrain Vehi).
cle: Saddle-ride type vehicle for running on uneven terrain, also called a four-wheel buggy. ) Is suitable for the power transmission device.

[0002]

2. Description of the Related Art FIG. 5 conceptually shows an ATV power transmission device. The power of the engine 21 is output from the front and rear output shafts via an internal transmission mechanism,
Power transmission means 22, such as a chain or a propeller shaft,
The signals are input to differentials 24 and 25 on the front and rear sides via the switch 23. Then, the engine power input to the differentials 24 and 25 is reduced by the mechanisms of the differentials 24 and 25, and
The rotation power is converted into right-angle rotation power and transmitted to wheels 28 and 29 via left and right drive shafts 26 and 27. In the example shown in the figure, the connection portion A between the drive shaft 26 on the front side and the differential 24, the wheel 2
A constant velocity universal joint is used for each of the connecting portions B with the reference numeral 8.
In some cases, a constant velocity universal joint may be used for the connecting portion C between the drive shaft 27 and the differential 25 on the rear side and the connecting portion D for connecting to the wheel 29. When propeller shafts are used as the power transmission means 22 and 23, connecting portions E and F between the propeller shaft and the output shaft of the engine (transmission mechanism) 21, and connecting portions G and H between the differentials 24 and 25 are respectively provided. In some cases, a speed universal joint is used.

FIG. 6 shows a drive shaft 2 on the front side.
6 is shown. The drive shaft 26 is connected with a sliding constant velocity so that the drive shaft 26 can take angular displacement and axial displacement in accordance with the movement of the wheel 28 at the time of cornering traveling or rough terrain traveling. A universal joint (constant velocity universal joint permitting angular displacement and axial displacement between two axes) 30 and a fixed type constant velocity universal joint (constant velocity universal joint permitting angular displacement between two axes) 31 are paired. use. In the example shown in the figure, one end of the drive shaft 26 is connected to the differential 24 via a sliding constant velocity universal joint (double offset type constant velocity universal joint) 30 (connection part A), and the other end of the drive shaft 26 is connected. Is connected to the wheel 28 via a fixed type constant velocity universal joint (Zepper type constant velocity universal joint: ball fixed joint) 31 (connection part B).

[0004]

In a constant velocity universal joint of a Zepper type or a double offset type, a retainer having a window-shaped pocket for accommodating and holding a torque transmitting ball is provided.
Bisection plane (θ / 2) of the operating angle (θ) of the torque transmitting ball
To maintain the uniform velocity of the joint. Generally, in this type of cage, a basic shape is formed by forging or press working, and then a window is formed in a pocket to obtain a required shape.

However, the constant velocity universal joint used for the power transmission device of the ATV is not required to have the same high durability as the constant velocity universal joint used for a passenger car or the like. Is reduced, so that the pocket size of the cage is smaller than that of the cage of the general configuration. On the other hand, high-angle compatibility is required so as to be able to follow large movements of wheels and suspensions when traveling on uneven terrain, and the like, so that the thickness of the cage is made slightly thicker than that of a general configuration. Under these circumstances, in the conventional configuration, there is a concern that it is difficult to form a window in the pocket of the retainer, which may cause an increase in cost.

Accordingly, the present invention is intended to provide a more inexpensive constant velocity universal joint by reducing the manufacturing cost of the retainer in consideration of the above features of the constant velocity universal joint for ATV.

[0007]

In order to achieve the above object, the present invention provides an outer joint member having a plurality of guide grooves formed on an inner diameter surface and an inner joint member having a plurality of guide grooves formed on an outer diameter surface. A torque transmission ball disposed on each of a plurality of ball tracks formed by a guide groove of the outer joint member and a guide groove of the inner joint member opposed thereto, and a plurality of window-shaped housings for accommodating and holding the torque transmission balls. Provided is a constant velocity universal joint including a cage having a pocket formed therein, wherein the cage is formed by molding including the pocket.

The constant velocity universal joint to which the present invention is directed is a constant velocity universal joint provided with a retainer having a window-shaped pocket, and specifically, a Zepper type constant velocity universal joint (undercut free type is also available). And double offset type constant velocity universal joints.

The term "mold forming" refers to a forming method for forming a desired shape using a forming die, and includes casting and powder metallurgy. By forming the cage including the pockets by molding, it is possible to eliminate the process of opening the pockets in the conventional cage and reduce the manufacturing cost.

When the cage is a cast product, it is preferable to use austempered spheroidal graphite cast iron from the viewpoint of securing the characteristics such as strength and toughness required for the cage. Austemper Ductile Cast Iro (ADI: Austemper Ductile Cast Iro)
n) is to perform austempering on spheroidal graphite cast iron,
It is a bainite base structure. It is known that spheroidal graphite cast iron is a structural material excellent in strength and toughness, but austempered spheroidal graphite cast iron has more excellent strength, toughness, wear resistance and the like than spheroidal graphite cast iron. For example, when compared by tensile strength, spheroidal graphite cast iron
gf / mm ² (784 MPa), whereas austempered spheroidal graphite cast iron has a maximum of 150 kgf / mm ² (1 MPa).
470 MPa).

The austempering treatment is a heat treatment method utilizing the isothermal transformation of an iron-based material. After the cage is cast using spheroidal graphite cast iron, it is heated to the austenite region, and a salt bath or lead-
Quench in a bismuth bath where it is held until the structure changes to bainite. Thereafter, the cage is removed from the bath and cooled to room temperature. If the holding temperature in the heat bath is high, upper bainite with feathery structure is generated, and if the holding temperature is lower, lower bainite with needle-like structure is generated. During the isothermal transformation, the untransformed austenite is stabilized by an increase in the amount of dissolved carbon, and remains after cooling at room temperature. This retained austenite shows a stress-induced transformation phenomenon, and when a certain level of stress is applied, it transforms into martensite and hardens. Therefore, retained austenite is effective in improving elongation, toughness, and fatigue strength. However, since it becomes a factor of difficult processing, the retained austenite may be completely bainite in some cases.

The cage may be made of a sintered metal. In this case, it is preferable to form the cage by injection molding of a metal powder in order to secure characteristics such as strength and dimensional accuracy of the cage.
Metal Injection Molding (MIM)
Is one of the molding techniques for metals, intermetallic compounds, etc., and a sintered body with a higher sintering density can be obtained compared to general powder metallurgy.
There is an advantage that a complicated and fine sintered metal product can be manufactured with high dimensional accuracy and its mechanical strength is high. The process of metal powder injection molding is basically a process of kneading a metal powder with a binder, a process of injection molding using the kneaded product, a process of performing a degreasing process on a compact, and a process of sintering a compact. including.

In particular, a constant velocity universal joint using a cage made of austempered spheroidal graphite cast iron and sintered metal by metal powder injection molding has the same strength as a conventional constant velocity universal joint. The durability required as a coupling for a power transmission device of an ATV can be satisfied.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the power transmission system of the ATV shown in FIG.
A fixed constant velocity universal joint (zepper type constant velocity universal joint: ball-fixed joint) 1 is shown (connection part B).

The constant velocity universal joint 1 has a spherical inner surface 2.
a, an outer joint member 2 in which a plurality of curved guide grooves 2b are formed in the axial direction; an inner joint member 3, in which a plurality of curved guide grooves 3b are formed in the spherical outer diameter surface 3a in the axial direction; Guide groove 2b of outer joint member 2 and inner joint member 3 opposed thereto
A plurality of torque transmitting balls 4 arranged on a ball track formed in cooperation with the guide groove 3b, and a retainer 5 for holding the torque transmitting balls 4. The boot 6 is mounted on the outer diameter portion of the outer joint member 2 and the outer diameter portion of the drive shaft 26, and is fixed by a boot band.

The center of curvature O of the guide groove 2b of the outer joint member 2
1 and the center of curvature O2 of the guide groove 3b of the inner joint member 3
It is offset to the opposite side by an equal distance F in the axial direction with respect to the joint center plane O including the center of the torque transmitting ball 4.

As shown in FIG. 2, the retainer 5 has a spherical outer diameter surface 5 which is guided in contact with the inner diameter surface 2a of the outer joint member 2.
a, an inner surface of a spherical inner surface 5b guided in contact with an outer surface 3a of the inner joint member 3, and a plurality of window-shaped pockets 5c for accommodating and holding the torque transmitting ball 4. The retainer 5 is made of austempered spheroidal graphite cast iron (ADI) or sintered metal by metal powder injection molding (MIM). In the former case, after casting and molding to the required shape shown in FIG. 2 using spheroidal graphite cast iron and performing austempering, if necessary, processing for ensuring accuracy (for example, outer diameter surface, inner diameter surface, etc.) (Grinding). In the latter case, molding by metal powder injection molding (MIM)
Through a sintering process, a sintered metal body having a required shape as shown in FIG. 2 is manufactured, and the sintered metal body is processed to ensure accuracy as required (for example, grinding an outer diameter surface, an inner diameter surface, etc.). And finish.

In the constant velocity universal joint 1, when the outer joint member 2 and the inner joint member 3 are angularly displaced by an angle θ,
The torque transmitting ball 4 guided to the retainer 5 is always maintained within the bisecting plane (θ / 2) of the angle θ at any operation angle θ, and the constant velocity of the joint is ensured.

FIG. 4 shows a sliding type constant velocity universal joint (double offset type constant velocity universal joint) 11 for connecting one end of the drive shaft 26 to the differential 24 in the power transmission device of the ATV shown in FIG. (Connecting part A).

The constant velocity universal joint 11 has a cylindrical inner surface 12.
a, an outer joint member 12 in which a plurality of linear guide grooves 12b are formed in the axial direction, and an inner joint member 13 in which a plurality of linear guide grooves 13b are formed in the spherical outer diameter surface 13a in the axial direction.
And a plurality of torque transmitting balls 1 arranged on a ball track formed by a guide groove 12b of the outer joint member 12 and a guide groove 13b of the inner joint member 13 opposed thereto.
4 and a retainer 15 that retains the torque transmitting balls 14.

As shown in FIG. 3, the cage 15 is guided in contact with the spherical outer diameter surface 15a of the outer joint member 12 and the outer diameter surface 13a of the inner joint member 13. And a plurality of window-shaped pockets 15c for accommodating and holding the torque transmitting balls 14. The center of curvature O3 of the outer diameter surface 15a and the center of curvature O4 of the inner diameter surface 15b are offset by the same distance f in the axial direction with respect to the axial center O 'of the pocket 15c. The cage 15 is made of austempered spheroidal graphite cast iron (AD) similarly to the cage 5 of the above-described embodiment.
I) or a sintered metal formed by metal powder injection molding (MIM).

In this constant velocity universal joint 11, when the outer joint member 12 and the inner joint member 13 are angularly displaced by an angle θ, the torque transmitting ball 14 guided by the retainer 15 always has an angle at any operating angle θ. Bisection plane of θ (θ /
2), the constant velocity of the joint is ensured. Also,
When the outer joint member 12 and the inner joint member 13 move relative to each other in the axial direction, a slip occurs between the outer diameter surface 15a of the retainer 15 and the inner diameter surface 12a of the outer joint member 12, and a smooth axial slide ( Plunging).

According to the present invention, not only the front side but also the constant velocity universal joints (coupling portions C and D) for coupling the rear side drive shaft 27 in FIG.
When a propeller shaft is used as 23, a constant velocity universal joint for connecting the propeller shaft (connection portions E, F, G,
H) can be similarly applied.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the embodiment shown in FIG. 1, a constant velocity universal joint in which the cage is made of austempered spheroidal graphite cast iron (Example product)
And a constant velocity universal joint (comparative product) made of a steel plate press as a cage, a strength test and a durability test were performed. The results are shown in Tables 1 to 3.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

[Table 3]

From the above test results, it was confirmed that the example product had the same strength as the comparative product. Although the durability is inferior to that of the comparative product, it is considered that the durability as a joint for an ATV power transmission device is satisfied.

[0030]

The present invention has the following effects.

(1) By forming the cage including the pockets by molding, it is possible to reduce the manufacturing cost by eliminating the process of opening the pockets in the conventional cage.

(2) In particular, since the retainer is made of austempered spheroidal graphite cast iron and a sintered metal formed by injection molding of metal powder, the same strength as that of a conventional constant velocity universal joint can be secured. The durability as a coupling for a power transmission device can be satisfied.

(3) According to the present invention, it is possible to provide a constant velocity universal joint which is inexpensive and lightweight, and which is particularly suitable for an ATV power transmission device.

[Brief description of the drawings]

FIG. 1 is a sectional view of a fixed type constant velocity universal joint according to a first embodiment.

FIG. 2 is a sectional view showing a retainer of the constant velocity universal joint shown in FIG.

FIG. 3 is a sectional view showing a retainer of the constant velocity universal joint shown in FIG. 4;

FIG. 4 is a sectional view of a sliding type constant velocity universal joint according to a second embodiment.

FIG. 5 is a conceptual diagram of an ATV power transmission device.

FIG. 6 is a side view (partial cross section) showing the drive shaft in FIG. 5;

[Explanation of symbols]

 Reference Signs List 1 constant velocity universal joint 2 outer joint member 2a inner diameter surface 2b guide groove 3 inner joint member 3a outer diameter surface 3b guide groove 4 torque transmission ball 5 retainer 5c pocket 11 constant velocity universal joint 12 outer joint member 12a inner diameter surface 12b guide groove 13 inner joint member 13a outer diameter surface 13b guide groove 14 torque transmitting ball 15 retainer 15c pocket

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshihiro Sagisaka 1578 Higashikaizuka, Iwata City, Shizuoka Prefecture (72) Inventor Yuji Kato 1578 Higashikaizuka, Iwata City, Shizuoka Prefecture

Claims (6)

[Claims] An outer joint member having a plurality of guide grooves formed on an inner diameter surface, an inner joint member having a plurality of guide grooves formed on an outer diameter surface, a guide groove of the outer joint member, and an inner joint member opposed thereto. Constant velocity universal joint comprising: a torque transmission ball disposed on each of a plurality of ball tracks formed by the guide grooves; and a retainer having a plurality of window-shaped pockets for accommodating and holding the torque transmission balls. The constant velocity universal joint according to claim 1, wherein the retainer is formed by molding including a pocket. 2. The constant velocity universal joint according to claim 1, wherein the retainer is formed by casting. 3. The constant velocity universal joint according to claim 2, wherein said cage is made of austempered spheroidal graphite cast iron. 4. The cage according to claim 1, wherein said cage is made of sintered metal.
The described constant velocity universal joint. 5. The constant velocity universal joint according to claim 4, wherein said retainer is formed by metal powder injection molding. 6. The constant velocity universal joint according to claim 1, which is used for a power transmission device of a saddle-ride type vehicle (ATV) for traveling on uneven terrain.