JPH01182635A - Driving force transmitting device - Google Patents

Abstract

PURPOSE:To contrive to prevent an reduction in clutch pressing force against differential rotation by providing a working piston with a pressure responding body which increases the capacity of a clutch chamber depending on an increase in pressure due to the volumetric expansion of lubricant in the clutch chamber. CONSTITUTION:Hydraulic pressure is developed depending on the differential rotation between a rotating housing 21 and a rotating shaft 22 by means of both a rotor 41 having a plurality of vanes and a hydraulic pressure developing means 23 composed of high viscosity oil 44 so as to drive a working piston 24. A piston inner 50 acting as a pressure responding body is coupled with the working piston 24 so that a space chamber 51 formed by the aforesaid pieces is communicated with a space 43 via the rotor 41, the working piston 24, each side clearance of an end cover 28 and the like. Hence, the pressure responding body is thereby actuated depending on an increase in pressure at the time of differential rotation, thereby making is possible to prevent an reduction in clutch pressing force.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a driving force transmission device used in a four-wheel drive vehicle.

<Prior Art> In a differential pump type torque transmission device used in a four-wheel drive vehicle, a differential pump is driven by the rotational speed difference between two drive shafts connected to the front wheels and the rear wheels, respectively. A multi-disc clutch is engaged by an actuating piston operated by a differential pump discharge pressure corresponding to this rotational speed difference, and torque is transmitted between the front wheels and the rear wheels.

However, in the differential pump type torque transmission device described above, it is necessary to incorporate a differential pump between the drive shafts of the front and rear wheels, which increases the number of parts and makes the device large and expensive. There is a problem.

In order to solve these problems, the applicant has developed a driving force transmission device (
Patent application No. 75240/1983) was proposed.

Such a driving force transmission device is provided with a space filled with high viscosity oil on the side of a piston that presses a multi-disc clutch, and is operated by relative rotation between a front wheel drive shaft and a rear wheel drive shaft. By storing a blade that moves high viscosity oil with this blade, pressure corresponding to relative rotation (differential rotation) is generated, and this pressure is applied directly to the piston to engage the multi-disc clutch. This is what I did.

<Problems to be Solved by the Invention> By the way, in this type of driving force transmission device, the clutch chamber housing the multi-disc clutch is filled with lubricating oil for lubricating the clutch plates.
When the temperature of the lubricating oil rises due to the frictional heat of the multi-disc clutch, the lubricating oil expands in volume, increasing the pressure within the clutch chamber, and this pressure acts on the actuating piston against the pressure exerted by the blades. This causes a problem in that the clutch pressing force by the actuating piston is reduced, and the transmission torque for differential rotation is reduced.

<Means for Solving the Problems> The present invention has been made in view of the above-mentioned conventional problems, and has a structure in which a drive shaft for both wheels is disposed between a front wheel drive shaft and a rear wheel drive shaft. A multi-disc clutch that transmits torque between
An operating piston that presses this multi-disc clutch, and a hydraulic pressure that generates hydraulic pressure on this operating piston in accordance with the differential rotation between the front wheel drive shaft and the rear wheel drive shaft, and applies this hydraulic pressure to the operating piston. a clutch chamber housing the multi-disc clutch is filled with lubricating oil, and the clutch chamber is actuated in response to a pressure increase due to volumetric expansion of the lubricating oil in the clutch chamber due to frictional heat of the multi-disc clutch. The actuating piston is equipped with a pressure-responsive body that increases the volume of the piston.

With the above configuration, when the temperature of the lubricating oil filled in the clutch chamber rises due to the frictional heat of the multi-disc clutch,
The lubricating oil expands in volume, and in response to the increase in pressure within the clutch chamber due to this volumetric expansion, the pressure-responsive body acts to increase the volume of the clutch chamber, thereby suppressing pressure addition within the clutch chamber. As a result, pressure in the opposite direction to the hydraulic pressure due to the blade does not act on the actuating piston, and the clutch pressing force by the actuating piston does not decrease as the temperature rises.

<Example> Embodiments of the present invention will be described below based on the drawings.

In FIG. 3, 10 is an engine, 11 is a transmission, 13 is a front wheel differential, 14 is a rear differential, 15 is a front wheel drive shaft, 16 is a rear wheel drive shaft, 17 is a front wheel, and 18 is a rear wheel drive shaft. is a rear wheel, 20 is a driving force transmission device provided between the front wheel drive shaft 15 and the rear wheel drive shaft 16, the output of the engine 10 is transmitted to the front wheel differential device 13 via the transmission 11, While driving the front wheels 17,
The rotation is transmitted to the front wheel drive shaft 15, and its rotation is transmitted to the rear wheel drive shaft 16 via the drive force transmission bag!20,
Drive 8.

As shown in FIG. 1, the driving force transmission device 20 includes a rotary housing 21, a rotary shaft 22 that extends vertically through the rotary housing 21 and is rotatably supported, and a rotary housing 21 and a rotary shaft 22. A hydraulic pressure generating means 23 that generates hydraulic pressure according to the differential rotation of the hydraulic pressure generating means 23 and an operating piston 24 to which the hydraulic pressure generated by the hydraulic pressure generating means 23 is applied are frictionally engaged by the pressing force of the operating piston 24. It is mainly composed of a multi-disc clutch 25.

The front wheel drive shaft 1 is disposed at one end of the rotating housing 21.
A hollow chamber 27 is formed concentrically with the rotating shaft 22 in the 0-rotation housing 21, in which the rear wheel drive shaft 16 is integrally connected within the rotating shaft 22. , one end of this hollow chamber 27 is closed with an end cover 28. The operating piston 24 is slidably fitted in the hollow chamber 27, and a clutch chamber 37 is formed between the operating piston 24 and the rotary housing 21 to accommodate the multi-disc clutch 25. The clutch chamber 37 is filled with lubricating oil for lubricating the multi-disc clutch 25. In addition, a plurality of outer plates 33 and inch plates 34 that constitute the multi-disc clutch 25 are arranged alternately in the clutch chamber 37. They are each spline-engaged to the outer periphery, and rotational torque is transmitted through frictional engagement between the two.

Between the working piston 24 and the end cover 28,
A cylindrical space 43 limited in the axial direction is formed, and a rotor 41 having a wall thickness slightly smaller than the axial dimension of the space 43 is housed in a slidable manner. As shown in FIG. 2, the rotor 41 has a center portion splined to the outer periphery of the rotating shaft 22, and has two blades 42 extending in the diametrical direction. The outer ends of these blades 42 are slidably fitted into the periphery of the hollow interior of the rotary housing 21. As a result, the space 43 between the actuating piston 24 and the end cover 28 has a plurality of blades 42
It is divided into a plurality of spaces on the circumference, and each of these spaces is filled with high viscosity oil 44 such as silicone oil. The rotor 41 having the blades 42 housed in the cylindrical space 43 and the high viscosity oil 44 constitute the hydraulic pressure generating means 23.

an actuating piston 24 fitted into the rotary housing 21;
A piston inner 50 is fitted to face the clutch chamber 37 side so as to be slidable by a predetermined amount in the same direction as the sliding direction of the actuating piston 24, and there is a space between the piston inner 50 and the actuating piston 24. A chamber 51 is formed. This space chamber 51 communicates with the space 43 through side clearances between the rotor 41, the actuating piston 24, and the end cover 28, and this space chamber 51 maintains low pressure regardless of the increase in the internal pressure of the space 43. Retained. Thus, the piston inner 50 is held at the center position in the axial direction with respect to the normally operating piston 24 by the force of springs 53 and 54 inserted on both sides thereof. The piston inner 50 slides in response to an increase in pressure in the clutch chamber 37, and functions as a pressure responsive body that increases the volume of the clutch chamber 37.

With the above configuration, when the front wheel drive shaft 15 and the rear wheel drive shaft 16 rotate relative to each other and the rotor 41 rotates relatively within the rotating housing 21, the high viscosity oil 44 filled in the space 43 is transferred to the blade 42. As a result, the fluid is forced to move between two closely spaced surfaces at a flow rate that corresponds to the rotational speed difference. At this time, an internal pressure proportional to the rotational speed of the rotor 41 is generated in the space 43 due to viscous friction between the end cover 28 and both end surfaces of the actuating piston 24 . In other words, when the blade 42 rotates in the direction of the arrow, for example, if the leading blade side of the space surrounded by two adjacent blades 42 is A and the succeeding blade side is B, then the internal pressure will be at point A. The pressure distribution is highest and lowest at eight points, and a pressure proportional to the rotational speed of the blade 420 is generated in the space 43, and this pressure acts on the actuating piston 24 to press the multi-disc clutch 25.

Therefore, a plurality of outer plates 33 and inch plates 34
are frictionally engaged by a pressing force corresponding to the hydraulic pressure acting on the actuating piston 24, and rotational torque is transmitted from the front drive shaft 1.5 to the rear drive shaft 16 via the multi-disc clutch 25.

By the way, the temperature of the lubricating oil filled in the clutch chamber 37 rises due to the frictional heat generated by the sliding friction of the multi-disc clutch 25, and as a result, the lubricating oil expands in volume and the pressure inside the clutch chamber 37 increases. do.

In response to this pressure increase, the piston inch (pressure responsive body)
50 is slid to increase the volume within the front chamber 3f. Therefore, the pressure increase in the clutch chamber 37 is suppressed, and the pressing force of the multi-disc clutch 25 is not reduced.

Note that when the volume of the lubricating oil contracts as the lubricating oil temperature decreases, the piston inner 50 is slid back to the neutral position by the action of the springs 53 and 54.

In the above embodiment, the hydraulic pressure acting on the actuating piston is generated by forcibly moving high viscosity oil with a blade, but it may also be generated using a conventionally well-known differential pump. .

Furthermore, in the above-described embodiment, the pressure-responsive body is constructed from the piston inner 50 that is slidably fitted into the actuating piston 24, but the pressure-responsive body may be constructed from a flexible body such as an elastically deformable diaphragm. You can also do it.

<Effects of the Invention> As described above, the present invention applies the pressure generated by the hydraulic pressure generating means to the actuating piston to operate the multi-disc clutch in response to the differential rotation between the front wheel drive shaft and the rear wheel drive shaft. For those that use pressing force, the clutch chamber is equipped with a pressure-responsive body that increases the volume of the clutch chamber in response to the rise in pressure caused by the rise in temperature of the lubricating oil filled in the clutch chamber. Even if the multi-disc clutch generates heat during differential rotation and the lubricating oil temperature rises, the pressure increase in the clutch chamber can be absorbed by the pressure-responsive body, which reduces clutch pressing force against differential rotation. It has the effect of not reducing the

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a sectional view of a driving force transmission device, FIG. 2 is a sectional view taken along the line ■-■ in FIG. 1, and FIG. 3 is a schematic diagram of a four-wheel drive vehicle. It is. 15... Front wheel side drive shaft, 16... Rear wheel side drive shaft, 2
1... Rotating housing, 22... Rotating shaft, 23...
- Hydraulic pressure generating means, 24... Working piston, 25...
Multi-plate clutch, 37...Clutch inner, 50...
Pressure responsive body.

Claims (1)

[Claims] (1) A multi-disc clutch that is disposed between the front-wheel drive shaft and the rear-wheel drive shaft and transmits torque between the two shafts, an actuation piston that presses the multi-disc clutch, and an actuation piston that presses the multi-disc clutch, and a a hydraulic pressure generating means that generates hydraulic pressure according to the differential rotation between the side drive shaft and the rear wheel side drive shaft and applies this hydraulic pressure to the actuating piston, and lubricates a clutch chamber housing the multi-disc clutch. The actuating piston is provided with a pressure-responsive body that is filled with oil and increases the volume of the clutch chamber in response to a pressure increase due to volumetric expansion of lubricating oil in the clutch chamber due to frictional heat of the multi-disc clutch. Force transmission device.