JPH056420Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention relates to a constant velocity universal joint used in the drive axle of an automobile. This invention relates to an improved structure of a double offset type constant velocity universal joint that allows for angular displacement and relative axial displacement between the two.

[Conventional technology]

A constant velocity universal joint that allows angular displacement and axial displacement is used for the drive shaft of front-wheel drive vehicles and rear-wheel drive vehicles with independent suspension. Conventional constant velocity universal joints are used in situations where angular or axial displacement occurs while transmitting torque from the drive shaft, such as while driving or idling when an automatic vehicle is stopped. Due to the high sliding resistance inside the joint, there was a problem in that vibrations from the engine were transmitted to the vehicle body, causing discomfort to the passengers.

That is, the conventional double offset type constant velocity universal joint, as shown in FIG. an inner member 4 having a groove 5 cooperating with the groove 2 to form a ball track and having an outer surface 6 having at least a partially spherical surface, and a torque transmitting ball 7 disposed in each groove 2, 5; and a ball pocket 9 for accommodating a torque transmission ball 7, which is guided by the cylindrical hole 3 of the outer member 1 and the partially spherical outer surface 6 of the inner member 4, and is located on both sides of the joint center on the joint axis. a partially spherical inner and outer surface 10 having a center of curvature spaced apart from each other by an equal amount;
11, and an inner member 4
The outer surface 6 of the retainer 8 and the inner surface 10 of the retainer 8 are brought into contact with each other with the same curvature, and the balls 7 are accommodated in the ball pockets 9 of the retainer 8 with an appropriate interference.

Therefore, when vibration acts on the constant velocity universal joint, slippage occurs between the outer member 1 and the balls 7, between the inner member 4 and the balls 7, and between the outer member 1 and the retainer 8. Moreover, since the ball 7 was restrained and could not rotate, the sliding resistance was large.

Therefore, the present applicant proposed a constant velocity universal joint in which the rotation of the ball 7 is facilitated and the sliding resistance is reduced (Japanese Patent Laid-Open No. 53-57341). This is done by making the radius (r) of the outer surface 6 of the inner member 4 different from the radius (R) of the inner surface 10 of the cage 8 (R>(r+δ)), and A predetermined axial gap 12 is formed between the member 4 and the cage 8. That is, the inner member 4 and the retainer 8 are intended to be able to move relative to each other in the axial direction, and vibrations are absorbed by this relative axial movement. Note that δ represents a spherical guide gap normally provided in a double offset type constant velocity universal joint.

[The problem that the idea attempts to solve]

However, when the torque load is large during acceleration,
If the torque that causes the balls to roll between the inner and outer members is greater than the force that restrains the balls due to the interference between the pockets of the retainer and the balls, the ball will not roll even with the above proposed structure. However, when the torque that tries to cause the ball to roll is smaller than the ball restraining force, such as when the engine of an automatic car is idling, the ball does not roll and rolls on the track. slipping,
The effect of absorbing vibration cannot be obtained.

The purpose of this invention is to enable relative axial movement between the retainer and the inner member, and to allow the balls to roll even under various large and small torques generated in the joint, with low sliding resistance and to absorb vibration. The objective is to provide a constant velocity universal joint that can

[Means to solve the problem]

This invention includes an outer member having a cylindrical hole provided with a linear guide groove, a groove that cooperates with the guide groove of this outer member to form a ball track, and a part of the outer member has a partially spherical shape. an inner member having an outer surface with
a ball pocket for accommodating the torque transmission ball, the ball pocket being guided by the cylindrical hole of the outer member and the partially spherical outer surface of the inner member, and being shifted to both sides of the ball center line in the axial direction of the joint; This is an improved structure of a constant velocity universal joint comprising a retainer having partially spherical inner and outer surfaces having disposed centers of curvature, and has the following features. That is, when viewed in a cross section that includes the axis of the joint, the outer surface of the inner member is formed by a uniform arc, and the axis between the cage and the inner member is formed between the inner surface of the cage and the outer surface of the inner member. To allow relative directional movement, the inner surface of the retainer is formed by an arc having a center of curvature offset in the radial direction from the center of curvature of the arc and having a radius of curvature larger than the radius of curvature of the arc of the outer surface of the inner member. ing. Further, an axial pocket gap of 5 to 50 microns is provided between the torque transmitting balls and the ball pockets of the retainer.

[Effect]

The presence of an axial pocket gap of 5 to 50 microns eliminates interference and releases the ball from axial clamping or restraint. As a result, for example, when vibration is applied to the inner member, the balls roll without resistance between the inner member and the outer member, allowing smooth relative movement between the inner member and the retainer, and the inner member The vibration absorbing function of the axial gap between the cage and the cage can be effectively exerted in any torque range.
This is due to the synergistic effect of the gap between the inner surface of the retainer and the outer surface of the inner member and the axial pocket gap.

〔Example〕

In FIG. 3 showing an embodiment of the present invention, 15
1 is an outer member (outer ring) of the constant velocity universal joint, 16 is an inner member (inner ring), 17 is a retainer, and 18 is a torque transmission ball. Note that this figure shows the joint in a stationary, neutral state. The outer member 15 is provided with a linear guide groove 20 on the cylindrical inner circumferential surface 19 . The inner member 16 has a partially spherical outer surface 21 that guides the partially spherical surface of the inner surface 24 of the retainer 17, and has a groove 22 on the outer surface 21 that forms a ball track with the guide groove 20 of the outer member 15. have. Retainer 1
7 has ball pockets 23 formed at equal intervals in the circumferential direction, and partially spherical inner and outer surfaces 24 and 25 having centers of curvature arranged on both sides of the ball center line and shifted by an equal amount in the axial direction of the joint. There is.

To enable relative movement in the axial direction with the inner member, the radius of curvature r of the outer surface of the inner member is set shorter than the radius of curvature R of the inner surface of the cage (R>r+
δ), and has an arcuate surface with a center of curvature located offset from the center of curvature of the inner surface of the cage.
In this embodiment, the radius of curvature (r) of the outer surface 21 of the inner member 16 is set shorter than the radius of curvature (R) of the inner surface 24 of the retainer 17 (R>(r+δ)), and
The center of curvature of the outer surface 21 of the inner member 16 and the retainer 1
The center of curvature of the inner surface 24 of 7 is offset in the radial direction. As a result, a predetermined spherical guide gap δ is formed between the two 21 and 24 at the center of the outer surface 21 of the inner member 16, and in areas other than the center, the inner member 16 is axially displaced in the axial direction. Gap 1
6 is formed.

Further, a gap 27 is provided between the axially opposing wall surface of the ball pocket 23 of the retainer 17 and the torque transmission ball 18. This pocket gap 27
is set in the range of 5 to 50 μ, taking into consideration the influence of collision between the balls 18 and the retainer 17, as well as releasing the restraint of the balls 18. In other words, if the upper limit of the pocket gap 27 is set to 55μ or more, not only will the hitting sound at the time of collision between the balls 18 and the retainer 17 become louder, but also the stability of the retainer 17 will be impaired due to the impact at the time of the collision. The problem described above will occur if the vibration is accelerated by the vibration, so set it to 50μ. In addition, the lower limit could theoretically be set to 0 since it releases the restraint of the ball 18, but
For manufacturing control purposes, it is set to 5μ in order to secure the pocket gap 27 by eliminating the tightening margin.

The constant velocity universal joint having the above structure has a structure in which the inner member 16 and the retainer 17 can move relative to each other in the axial direction due to the presence of the axial clearance 26.
is not restrained by the ball pocket 23 of the retainer 17 and can roll without resistance, so the sliding resistance to relative movement in the axial direction between the outer member 15 and the inner member 16 is very small. , when vibration from the engine side is applied with torque applied, internal vibrations occur via the retainer 17.
Vibration is absorbed by the smooth minute relative movement between the outer members 16 and 15, and transmission of vibration to the vehicle body is prevented. Furthermore, since the sliding resistance inside the joint is small, angular displacement and axial displacement can be performed extremely smoothly.

[Effect of idea]

According to this invention, as described above, the sliding resistance inside the joint becomes extremely small, so that the relative angular displacement and axial displacement between the outer member and the inner member are extremely smooth. Therefore, when the constant velocity universal joint is used in the drive axle of an automobile, even when a relatively small torque is applied, such as when idling in an automatic transmission vehicle, the amount of torque from the engine is reduced. Since vibrations are absorbed and transmission to the vehicle body is cut off, vehicle body vibrations can be suppressed.

The above-mentioned effects of this invention will be explained in detail below with reference to FIGS. 4 to 6 showing the test results.

Figure 4 shows the load torque (Kgf・
The graph shows the change in slide resistance (Kgf) with respect to m). Here, "DOJ" refers to the axial clearance (gap 26 in Figs. 2 and 3) that allows relative axial movement between the cage and the inner member, and the ball pocket between the torque transmission ball and the cage. (Gap 2 in Figures 2 and 3)
7) means a standard double offset type constant velocity universal joint without. "DOJ-RP" means "DOJ"
In other words, an axial clearance is provided to allow relative axial movement between the retainer and the inner member, that is, JP-A-53-
Means the one in Publication No. 57341. "DOJ-RPC"
The double bearing according to the present invention has an axial clearance 26 that allows relative axial movement between the retainer and the inner member and an axial pocket clearance 27 between the torque transmission ball and the ball pocket of the retainer. Refers to an offset type constant velocity universal joint. Fourth
The figure shows that "DOJ-RP" has lower sliding resistance than "DOJ", but compared to "DOJ-RP", "DOJ-RPC" (this invention) has much lower sliding resistance. I understand.

Figure 5 shows three types of load torque (5, 10, 15 kg
The results of measuring the static sliding resistance when the shaft is pushed 2 to 2.5 mm in the axial direction under the following conditions are shown. The horizontal axis shows the axial thrust amount (mm) from the center position of the cage and the balls, and the vertical axis shows the slide resistance (Kgf).

FIG. 6 shows the results of measuring slide resistance under axial vibration, which was performed assuming idling in the torque load region of an automatic transmission vehicle. The horizontal axis shows the axial displacement (mm), and the vertical axis shows the sliding resistance (Kgf).
Note that the excitation conditions are 23 Hz and ±0.25 mm, and although multiple curves overlap in the actual data, they are schematically represented as a line diagram for convenience of representation.

In Figures 5 and 6, A is a standard double offset type constant velocity universal joint (Figure 1) that provides interference between the ball and ball pocket, and B is a standard double offset type constant velocity universal joint (Figure 1). Universal joint (Fig. 1)
C is a case in which a gap of approximately 20μ is provided between the ball and the ball pocket, and C is a case in which the gap between the ball and the ball pocket is approximately 20μ in the double offset type constant velocity universal joint of the present invention.

In FIG. 5, the curve rises quickly at A, indicating that the sliding resistance is large.
In case B, the area where the sliding resistance is almost zero is small, and the vibration of the car cannot be absorbed in this area. this is,
This is because there is little axial clearance or backlash between the inner member and the retainer, and the inner member and the retainer are quickly restrained. That is, in this case, since there is only a spherical guide gap (δ in the drawings of this application) between the inner member and the retainer,
The axial clearance or backlash between the inner member and the retainer is approximately 0.3 mm at most, and this does not have the ability to absorb vehicle vibrations. On the other hand, in C (the present invention), the region of slide resistance≈0 is much longer than in the former two, and it is therefore clear that it is extremely excellent in absorbing vibrations in the axial direction. This is also supported by Figure 6. In other words, as shown in Fig. 6, C has a lower sliding resistance than A and B at any torque. For example, when the torque is 15 kgm, C has 6 kgf compared to 163 kgf for A and 76 kgf for B. This is a much smaller value.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view showing the structure of a typical double offset type constant velocity universal joint, and Figure 2 is an enlarged cross-sectional view of the main parts showing the structure of a conventional constant velocity universal joint that reduces sliding resistance inside the joint. , FIG. 3 is an enlarged sectional view of a main part of a constant velocity universal joint showing an embodiment of the present invention. Figure 4 is a graph showing changes in sliding resistance with respect to load torque under vibration, and Figure 5 shows the results of measuring static sliding resistance when pushing the shaft in the axial direction under three types of load torque. The graph shown in FIG. 6 is a graph showing the results of measuring slide resistance under axial vibration, which was performed assuming idling in the torque load region of an automatic transmission vehicle. 15... Outer member, 16... Inner member, 17...
...Retainer, 18...Torque transmission ball, 20...
Guide groove, 21... Outer surface of inner member, 23... Ball pocket, 24... Inner surface of retainer, 26...
...Axial clearance, 27...Pocket clearance.

Claims (1)

[Claims for Utility Model Registration] An outer member having a cylindrical hole provided with a linear guide groove, and a groove that cooperates with the guide groove of the outer member to form a ball track, and an inner member having an outer surface with a partially spherical shape, torque transmission balls disposed in each of the grooves, and a ball pocket for accommodating the torque transmission balls; The cage is guided by the partially spherical outer surface of each member, and has partially spherical inner and outer surfaces with centers of curvature shifted on both sides of the ball center line in the axial direction of the joint. In a joint, when viewed in a cross section including the axis of the joint, the outer surface of the inner member is formed by a uniform arc, and there is a gap between the retainer and the inner member between the inner surface of the retainer and the outer surface of the inner member. To allow relative axial movement, the inner surface of the cage has a center of curvature offset in the radial direction from the center of curvature of the arc, and is formed by an arc with a radius of curvature larger than the radius of curvature of the arc on the outer surface of the inner member. 1. A constant velocity universal joint characterized in that an axial pocket gap of 5 to 50 μm is provided between a torque transmission ball and a ball pocket of a retainer.