JPH03107659A - Power transmission device for vehicle - Google Patents

Abstract

PURPOSE:To obtain a proper axial load according to conditions by interposing a spacer made of a shape memory material between a pair of taper roller bearings for rotatably supporting a drive bevel pinion shaft in a differential case. CONSTITUTION:By the fastening force of a nut 8, axial loads are given to taper roller bearings 4a, 4b, and the loads added to the bearings 4a, 4b are held constant by the presence of a spacer 20. As the spacer 20 is made of a shape memory alloy, the spacer 20 is laid in stretched state at the time of start and departure wherein the oil temperature in a differential case 1 is low, and the axial loads added to the bearings 4a, 4b are suppressed low, so that the start and departure can be easily conducted under low load. When the oil temperature is increased during running, the spacer 20 is laid in contracted state, and the axial loads added to the bearings 4a, 4b are relatively increased, reducing the gearing noise between a pinion 3 and a ring gear 5.

Description

[Detailed description of the invention] a. Industrial application field The present invention relates to a power transmission device for a vehicle.

b6 Conventional technology Figure 5 shows the rear axle of an automobile, in which 1 is a differential case, 2 is a drive bevel pinion shaft, and 3 is a shaft provided at one end of the drive bevel pinion shaft 2. Drive bevel binion (reduction small gear), 4a, ,ib hat' Live bevel binion shaft 2 to differential case 1
A pair of tapered roller bearings (conical roller bearings) are rotatably supported inside, 5 is a ring gear (reduction large gear) that meshes with the drive bevel pinion 3, 6 is a drive bevel pinion shaft 2 and a propeller shaft (not shown). The connecting member 7 that connects the two to each other is a steel spacer interposed between the pair of tapered roller bearings 4a and 4b.

A nut 8 is screwed onto the other end of the upper 3M drive bevel pinion shaft 2, and the tightening force of this nut 8 constantly applies an axial load (preload) to the pair of tapered roller bearings 4a and 4b. It is being Therefore, the drive bevel pinion shaft 2 is always rotated under a load (preloaded state). As a result, the m-beating sound (def noise) between the drive bevel pinion shaft 2 and the drive bevel pinion 3 due to a change in the load applied to the drive bevel pinion shaft 2 is reduced.

Furthermore, the steel spacer 7 is arranged between the pair of tapered roller bearings 4a, 4b, so that even if the bearings 4a, 4b are displaced by an axial load, these bearings 4a,
This is to keep the load applied to 4b constant.

C1 Problems to be Solved by the Invention In the conventional case as described above, the displacement of the steel spacer 7 (displacement in the axial direction due to the tightening force of the nut 8) is small under the initial assembled condition. Therefore, it may not be possible to apply a sufficient axial load. Furthermore, due to axial displacement of the propeller shaft due to changes in vehicle behavior, the coupling member 6 and the pair of tapered roller bearings 4a, 4
In some cases, a load is applied to the steel spacer 7 via b, causing a problem in which the amount of displacement changes. Also, from the steel spacer 7 to the tapered roller bearings 4a, 4h
The reality is that once the axial load is assembled, it cannot be changed during driving.

The present invention has been made in view of the above circumstances, and its purpose is to provide a power transmission device for a vehicle that can obtain an appropriate axial load depending on the situation.

d. Means for Solving the Problems In order to achieve the above-mentioned object, in the present invention, a shape memory material is used between a pair of tapered roller bearings that rotatably supports a drive bevel pinion shaft in a differential case. A spacer consisting of the following material is interposed.

Hereinafter, one embodiment of the present invention will be described with reference to FIGS. 1 to 4. Note that the same reference numerals are used for parts in FIG. 2 that are common to those in FIG. 5.

FIG. 1 shows a power transmission system 1o for a four-wheeled vehicle 9, in which power from an engine 11 is transmitted to rear wheels 14a, 14 via a propeller shaft 12 and a reduction gear mechanism 3 on the rear axle.
b.

As clearly shown in FIG. 2, the above-mentioned speed reduction device 13 includes a drive bevel pinion shaft 2 inserted into the differential case 1 and a differential mechanism (differential device) 15. An umbrella-shaped drive bevel pinion 3 is integrally provided at one end of the drive bevel pinion shaft 2 described above, and the shaft 2 is inserted into the differential case l by a pair of tapered roller bearings (conical roller bearings) 48° 4b. It is inserted and arranged in a rotatable state. A connecting member 6 is spline-coupled to the other end of the drive bevel pinion shaft 2, and a nut 8 is screwed into the tip of the shaft 2. Then, by the tightening force of this nut 8,
The connecting member 6 is engaged with the inner race 1.6a of the tapered roller bearing 4a, the drive bevel pinion 3 is engaged with the inner race 16b of the tapered roller bearing 4b, and the outer race of the tapered roller bearings 4a, 4b is engaged. 17a, 17b
are the stepped portions 18a and 18b of the differential case 1.
are engaged with each other.

On the other hand, one end of a propeller shaft 12 is integrally attached to the flange portion 6a of the connecting member 6 by bolting.

In addition, these pair of tapered roller bearings 4a,
A spacer 20 made of a shape memory alloy is interposed between the inner races 1.6a and 1.6b of the inner race 4b. As clearly shown in FIG. 3, this spacer 20 has both end portions formed into a cylindrical shape, and the middle portion thereof is formed as a protruding portion 20a extending over the entire circumference. It is arranged in a state where it is bent in the direction. In addition, as shown in FIG. 4, the above-described spacer 20 made of shape memory alloy has a physical property of expanding and contracting in the axial direction depending on the temperature, and has two transformation points A and B. in particular,
It has the characteristic of elongating (expanding) at low temperatures and contracting (shrinking) at high temperatures.

In addition, in FIG. 2, 21 is a differential pinion shaft, 22 is a differential pinion, 2
3a and 23b are driving wheel axles, and the differential case 1 is filled with oil (defoil).

e. Effect: Thus, the tightening force of the nut 8 applies an axial load to the tapered roller bearings 4a, 4b, and
The load applied to the tapered roller bearings 4a and 4b is maintained constant by the presence of the spacer 20.

In the case of this embodiment, since the spacer 20 is made of a shape memory alloy, the spacer 20 is displaced in the axial direction (elongation 11) according to the temperature (oil temperature) inside the differential case l, and accordingly, the tapered roller bearing 4a The axial load acting on 4b changes.

That is, since the oil temperature is low when starting and starting the automobile, the spacer 20 is placed in an expanded state, and the axial load applied to the tapered roller bearings 4a, 4b is suppressed to a low level. Therefore, starting and starting can be easily performed under low load.

Further, when the automobile is running normally or at high speed, the oil temperature becomes high, so the spacer 20 is placed in a contracted state and the axial load applied to the tapered roller bearings 4a, 4b is relatively increased. Therefore, rattling noise (default noise) generated between the drive bevel pinion 3 and the ring gear 5, which are rotating at high speed, is significantly reduced.

Although one embodiment of the present invention has been described above, the present invention is not limited to the embodiment described above, and various modifications and changes can be made based on the technical idea of the present invention.

For example, in the above embodiments, the spacer 20 is made of a shape memory alloy, but the spacer 20 is not limited to this, and any material that can change its shape depending on the temperature, such as a shape memory resin, may be used. Materials may also be used.

f. Effects of the Invention As described above, the present invention provides a spacer made of a shape memory material that is interposed between a pair of tapered roller bearings in order to apply an axial load to the bearings and maintain the load constant. Since the axial load applied to the tapered roller bearing can be changed according to the expansion/contraction (displacement) of the spacer due to temperature changes, it is possible to improve startability and starting performance at low temperatures. It is possible to reduce rattling noise (default noise) during high-speed driving.

Further, according to the present invention, since the magnitude of the axial load is adjusted based on the temperature, there is no risk of inconveniences such as unexpected loss of load.

[Brief explanation of drawings]

1 to 4 show one embodiment of the present invention, in which FIG. 1 is a schematic plan view showing a power transmission device for a four-wheeled vehicle, FIG. 2 is a sectional view of a reduction gear device, and FIG. 4 is a characteristic diagram showing the relationship between temperature and displacement of the spacer, and FIG. 5 is an enlarged sectional view of a main part of a conventional speed reduction device. 1...Differential case, 2...Drive bevel pinion shaft, 3-F
Live bevel pinion, 4a, 4b...Taper roller bearing, 5...
- Ring gear, 6... Connecting member, 8... Nut, 10... Power transmission device, 13... Reduction device, 15... Differential mechanism, 20... Spacer made of shape memory alloy. 4b Figure 2

Claims (1)

[Claims] A power transmission device for a vehicle, characterized in that a spacer made of a shape memory material is interposed between a pair of tapered roller bearings that rotatably support a drive bevel pinion shaft within a differential case.