JPH0425625A - Driving force transmission - Google Patents

Abstract

PURPOSE:To increase transmission torque according to increase in differential rotation speed and make variable the torque transmission by a relative rotation. CONSTITUTION:When relative rotation occurs between both propellor shafts 25, 26, viscous fluid in a reservoir R2 flows at a speed proportional to relative rotational speed. Then pressure in the chamber R2 increases gradually to push a working piston 13 in an axial direction thereby allowing a frictional clutch 10b to transmit torque proportional to differential rotation speed. A leaf spring 18 at the force end of a vane part is bent to reduce a gap with respect to a fluid chamber outer circumferential face 13 with fluid pressure when the relative rotation is in a specified direction and thereby the pressing force to the piston 13 is increased. When the relative rotation is another specified direction, the leaf spring is bent to increase the gap to reduce the pressing force to the piston 13. Thereby transmission torque is made substantially zero (0) to prevent seizure to the clutch 10b.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a driving force transmission device that is interposed between coaxially supported rotating members and transmits torque between these two members.

(Prior Art) Such a driving force transmission device is interposed between two rotating members that are supported coaxially with each other, and connects these two members so that torque can be transmitted to each other when these two members rotate relative to each other. There are two types of mechanisms: those used as coupling mechanisms for driving rotating members, and those used as differential limiting mechanisms for limiting the difference in rotation between these two members. The former coupling mechanism is mainly installed in one of the power transmission lines in a real-time four-wheel drive vehicle, and the latter differential limiting mechanism is mainly installed in each differential in the vehicle.

However, as a conventional driving force transmission device,
As shown in Japanese Patent No. 240429, it is disposed between both inner and outer rotating members that are coaxially and relatively rotatably positioned,
a friction clutch that is actuated by the relative rotation of these two rotating members to generate a frictional engagement force that connects the two rotational members so that torque can be transmitted, and that increases or decreases the frictional engagement force in accordance with the applied axial pressing force; A pressing force generating means is provided for generating an axial pressing force corresponding to the relative rotation of the two rotating members and applying it to the friction clutch, and the pressing force generating means is arranged between the two rotating members in a fluid-tight manner in the axial direction. an actuating piston that is slidably attached to the outer rotating member and integrally rotatable with the outer rotating member and faces one side of the friction clutch; a fluid chamber in which a viscous fluid is sealed; and a rotor having one or more vanes extending in the radial direction and integrally rotatably assembled to the inner rotating member in the fluid chamber. There is a transmission device.

In this type of driving force transmission device, when relative rotation occurs between both rotating members, relative rotation occurs between the rotor and the actuating piston, which is assembled to the outer rotating member so as to be integrally rotatable.
The viscous fluid within the fluid chamber is forced to flow by the vane portion of the rotor in the fluid chamber, and pressure is generated within the fluid chamber due to flow resistance or the like. That is, a pressure corresponding to the differential rotation speed is generated in the pressing force generating means. This pressure pushes the actuating piston in the axial direction, causing the friction clutch to be pressed and generating a frictional engagement force in the clutch that connects both rotating members in a torque-transmitting manner. This frictional engagement force is proportional to the differential rotation speed, and a torque proportional to the differential rotation speed is transmitted between the two rotating members from one side to the other. Therefore, the driving force transmission device functions as a connection mechanism between the driving side rotating member and the driven side rotating member in one power transmission path of the four-wheel drive vehicle, and also functions as a connection mechanism between the driving side rotating member and the driven side rotating member, and between the driving side rotating member and the driven side rotating member. It also functions as a differential limiting mechanism between rotating members or between both driven rotating members.

(Problems to be Solved by the Invention) By the way, in the above-mentioned type of driving force transmission device,
The torque transmission characteristic with respect to the differential rotation speed between both rotating members is as shown in graph A in FIG.

That is, the rate of increase of the transmitted torque with respect to the differential rotation speed gradually decreases as the differential rotation speed increases. The main cause of this is the decrease in viscosity due to temperature rise of the viscous fluid.
Such torque transmission characteristics help avoid the tight wheel braking phenomenon at low differential rotations and improve the ability to escape from rough roads (
It is difficult to simultaneously improve the torque transmission characteristics (during high differential rotation), and for this reason, the torque transmission characteristics are generally set to be low.

In addition, in this driving force transmission device, the torque transmission characteristics hardly change whether the relative rotation is forward or reverse, and compatibility with an anti-braking system becomes a problem.

Therefore, an object of the present invention is to increase the rate of increase in the transmission torque as the differential rotation speed increases, and to change the torque transmission characteristics depending on the relative rotation direction in this type of driving force transmission device.

(Means for Solving the Problems) The present invention provides a driving force transmission device of the type described above, in which a predetermined gap is secured between the tip of the vane portion of the rotor and the outer peripheral surface of the fluid chamber. In addition, the tip of the vane portion has a width in the axial direction of the vane portion and a width between the grooves, and the viscous fluid pressure generated when the rotor rotates relative to the outer rotating member causes the rotor to move in one direction. The present invention is characterized in that a spring member is provided that is close to the outer circumferential surface of the fluid chamber during differential rotation, and is bent in a direction away from the outer circumferential surface of the fluid chamber during differential rotation in the other direction.

(Operations and Effects of the Invention) In the driving force transmission device having such a configuration, the fluid pressure of the viscous fluid generated by the constant relative rotation of the rotor is increased as the relative rotation speed increases. The spring member provided at the tip of the portion gradually approaches the outer circumferential surface of the fluid chamber when rotating in one direction to gradually reduce the gap with the outer circumferential surface, and maintains the gap when rotating in the other direction, or Alternatively, it may be gradually spaced apart from the outer circumferential surface to gradually widen the gap with the outer circumferential surface. As a result, when the rotor rotates relative to one direction, the rate of increase in the transmitted torque increases as the differential rotation speed increases, as shown in graph B in Figure 5. Improves escape performance. Also,
During relative rotation of the rotor in the other direction, graph C in Fig. 5
As shown in FIG. 2, since the rate of increase in the transmitted torque decreases significantly as the differential rotation speed increases, it is possible to suitably respond to an anti-braking system.

(Example) Examples of the present invention will be described below based on the drawings.
The figure shows an embodiment of the driving force transmission device according to the present invention. As shown in FIG. 4, the driving force transmission device 10 is disposed in a rear wheel power transmission path of a real-time four-wheel drive vehicle.

In this vehicle, the front wheels are always driven and the rear wheels are driven when necessary, and the transaxle 22 attached to one side of the engine 21 is a transaxle.

It is equipped with a silane and a transfer, and outputs power from the engine 21 to the axle shaft 23 to drive the front wheels 24 and also outputs it to the first propeller shaft 25. The first propeller shaft 25 is connected to the second propeller shaft 26 via the drive force transmission device 10, and when both shafts 25 and 26 can transmit torque, the power is transmitted to the axle shaft 2 via the rear differential 27.
8, and the rear wheels 29 are driven.

Thus, the driving force transmission device 10 includes a pressing force generating means 10a and a friction clutch 10b in an annular working chamber consisting of an outer case 11 and an end cover 15, which are outer rotating members, and an inner shaft 12, which is an inner rotating member. There is.

The outer case 11 has a cylindrical portion 11a having a predetermined length, and has an inward seven-point flange portion Ilb at one end, and an end cover 15 is screwed onto the opening at the other end of the cylindrical portion 11a.

The inner shaft 12 includes an outward flange portion 12b on the outer periphery of the intermediate portion of a stepped cylindrical portion 12a having a predetermined length, and an outer spline portion 12c extending in the axial direction on the outer periphery of the flange portion 12b.
An internal spline portion 12d extending in the axial direction is formed on the inner periphery of one end of the cylindrical portion 12a. In the inner shaft 12, one end of the cylindrical portion 12a is fitted into the inner hole of the inward flange portion 11b of the outer case 11, and the other end is fitted into the inner hole of the end cover 15 in a fluid-tight and rotatable manner. It is supported by The inner shaft 12 is fixed at its inner spline portion 12 d by fitting into the spline 26 a at the tip of the second propeller shaft 26 , and the outer case 11 is fixed to the spline 26 a at the tip of the second propeller shaft 26 .
It is fixed to the rear end of 5.

The pressing force generating means 10a includes an operating piston 13 and a rotor 14, and the friction clutch 10b is of a wet type multi-plate clutch type, and includes a large number of clutch plates 16 and clutch discs 17.

Each clutch plate 16 has a spline portion on its outer periphery fitted into a spline portion 11c provided on the inner periphery of the outer case 11, and is assembled to the case 11 so as to be integrally rotatable and movable in the axial direction.

Each taranochi disk 17 has a spline portion on its inner circumference fitted into an outer spline portion 12c of the inner shaft 12, is located between each clutch plate 16, and is assembled to the shaft 12 so that it can rotate integrally and move in the axial direction. It is attached. A predetermined amount of clutch oil and gas are sealed in the storage chamber R1 of the clutch plate 16 and the clutch disc 17.

The actuating piston 13 constituting the pressing force generating means 10a is rotatable integrally with the inner periphery of the other end side of the cylindrical portion 11a of the outer case 11 in a fluid-tight manner, and is slidable in the axial direction. They are respectively assembled to the outer periphery thereof in a fluid-tight manner so as to be rotatable and slidable in the axial direction, and the other side surface 13a is in contact with the clutch plate 16 at the rightmost end in the figure.

As shown in FIGS. 1 and 2, the rotor 14 includes two vane portions 14b extending in the radial direction at positions 180° apart from each other on the outer periphery of the annular boss portion 14a.
4a, it is fitted onto the outer periphery of the cylindrical portion 12a of the inner shaft 12, and is assembled so as to be able to rotate integrally with the shaft 121. The rotor 14 is formed to have approximately the same thickness as the depth of the annular recess 13b provided on one side of the actuating piston 13 (1) and is fitted into the annular recess 13b. It is fluid-tightly fitted to the outer periphery of the other end of the cylindrical portion 12a so as to be slidable and rotatable in the axial direction, and is secured to the outer case 11 so as to be movable forward and backward, and is fluid-tight. In such an end cover 15, the position g in the axial direction is adjusted and fixed to the outer case 11 by caulking means, and the - side surface 15a abuts the annular outer edge surface 13c on one side of the operating piston 13, and the -
The side surface 158 and the annular recess 13b of the working piston 13 form a fluid chamber in which the rotor 14 is located. This fluid chamber is filled with a highly viscous fluid such as silicone oil, and the rotor 14 divides the fluid chamber into two retention chambers R2 by its vane portion 14b.

In this embodiment, as shown in FIGS. 1 to 3, the vane portion 14b of the rotor 14 is formed to a length that ensures a predetermined gap 21 between its tip and the outer peripheral surface +3d of the fluid chamber. A leaf spring 1 is attached to the tip of the vane portion 14b.
8 is fixed.

The leaf spring 18 is made of a shape memory alloy and has approximately the same width as the axial width of the vane portion 14b, and extends in an expanded state toward one end or the other end in the rotational direction of the vane portion 14b. The gap between the fluid chamber and the outer circumferential surface 13d is 92.

In the driving force transmission device 10 having such a configuration, torque is transmitted when relative rotation occurs between the first and second propeller shirts 25 and 26. That is, when relative rotation occurs between these two shafts 25 and 26, the outer case 11, the operating piston 13, and the end cover 15, which are assembled to the first propeller shaft 25 so as to be able to rotate integrally with each other,
Relative rotation occurs between the inner shaft 12 and the rotor 14, which are assembled to the shaft 26 of the second propeller 7 so as to be rotatable together. Therefore, in the fluid chamber of the pressing force generating means 10a, the viscous fluid in the retention chamber R2 is forced to flow at a speed proportional to the relative rotational speed, and the viscous fluid in the retention chamber R2 moves relative to each other sequentially in the circumferential direction. Due to the resistance, a pressure distribution is generated in which the pressure is gradually increased from the downstream end of the vane section 14t) to the upstream end of the next vane section 14b. The increased pressure portion of this pressure distribution increases in proportion to the differential rotation speed, and presses the actuating piston 13 in the axial direction.

As a result, the actuating piston 13 presses the friction clutch 10b, and each clutch plate 16 and clutch disc 17
are frictionally engaged via clutch oil. As a result, in the friction clutch 10b, torque proportional to the differential rotation speed is transmitted from the outer case 11 to the inner shaft 12, and the vehicle enters a four-wheel drive state. Furthermore, in this four-wheel drive state, differential rotation between the front and rear wheels is allowed, and tight corner braking is also prevented from occurring.

By the way, in the driving force transmission device 1O, the plate 1<nee 18 provided at the tip of the vane portion 14b of the rotor 14 is rotated when the rotor 14 rotates relative to the outer case 11 in the direction of the arrow (during positive differential rotation). ) is bent in the direction approaching the outer peripheral surface 13d of the fluid chamber due to the fluid pressure of the viscous fluid, and the gap 9
2 is gradually decreased according to the differential rotation speed. Therefore, the pressing force on the actuating piston 13 gradually increases as the differential rotation speed increases, and the transmitted torque with respect to the differential rotation speed becomes the state shown in graph B in FIG. Further, when the rotor 14 rotates relative to the outer case 11 in the direction of arrow E (during reverse differential rotation), the leaf spring 18 is bent in the direction away from the outer peripheral surface 13d of the fluid chamber due to the fluid pressure of the viscous fluid, and the gap 22 Make it bigger. Therefore, the pressing force on the actuating piston 13 is extremely small and substantially constant, and the transmitted torque with respect to the differential rotational speed is in the state shown in graph C in FIG. 5. on the other hand,
When high differential rotation occurs continuously in the driving force transmission device 10, the viscous fluid in the fluid chamber becomes high temperature, and the leaf spring 18 made of the shape memory alloy is heated as shown by the dashed line in FIG. The gap between the fluid chamber and the outer circumferential surface 13d becomes 23.
It gets bigger. As a result, the pressing force against the actuating piston 13 is almost eliminated, the transmitted torque becomes approximately zero, and the friction clutch 10b is prevented from burning out.

In the above embodiment, the rotor 14 is disposed between the actuating piston 13 and the end cover 15, but the rotor 14 may be disposed between the bottom wall of the outer case 11 and the actuating piston 13. , a friction clutch 10b may be disposed between the actuating piston 13 and the end cover 15.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a driving force transmission device according to an embodiment of the present invention, FIG. 2 is a cross-sectional view taken in the direction of the arrow n--n in FIG. 1, and FIG. An enlarged view, FIG. 4 is a schematic diagram of a vehicle employing the same device, and FIG. 5 is a graph showing torque transmission characteristics. Explanation of symbols 10... Drive force transmission device, IOa... Pushing force generating means, 10b... Friction clutch, 11... Outer case, 12... Inner shaft, 13... Operating piston, 13d ...Outer peripheral surface of the fluid chamber, 14...
Rotor, 14b... Vane part, 15... End cover 16... Clutch plate, 17... Clutch disc, 18゛・Flat spring, 25.26... Propeller/yaft, R2... Retention chamber (fluid chamber).

Claims (1)

[Claims] It is disposed between the inner and outer rotating members that are coaxially and relatively rotatably positioned, and is actuated by the relative rotation of these rotating members to generate and apply a frictional engagement force that connects the two rotating members so that torque can be transmitted. A friction clutch that increases or decreases the friction engagement force in accordance with an axial pressing force, and a pressing force generating means that generates an axial pressing force in accordance with the relative rotation of both rotating members and applies it to the friction clutch, an actuating piston in which the pressing force generating means is slidable fluid-tightly in the axial direction between the two rotary members and integrally rotatably assembled with the outer rotary member, and is opposed to one side of the friction clutch;
a fluid chamber formed between the outer rotating member and the actuating piston, having a predetermined interval in the axial direction, and enclosing a viscous fluid;
A driving force transmission device comprising a rotor including one or more vane portions extending in a radial direction and integrally rotatably assembled to the inner rotating member in the fluid chamber, wherein the vane portions of the rotor are the same. The vane portion is formed to a length that ensures a predetermined gap between the tip of the vane portion and the outer peripheral surface of the fluid chamber, and the tip of the vane portion has a width that is approximately the same as the width in the axial direction of the vane portion. Due to the viscous fluid pressure generated when the rotor rotates relative to the outer rotating member, the rotor moves close to the outer circumferential surface of the fluid chamber during differential rotation in one direction, and separates from the outer circumferential surface of the fluid chamber during differential rotation in the other direction. A driving force transmission device comprising a spring member that bends in a direction.