JPH05202962A - Drive force transmission device - Google Patents

Abstract

PURPOSE:To lock up a friction clutch with small thrust when a differential rotation between both rotation members becomes large, in a drive force transmission device provided with the friction clutch for transmitting torque of both inner and outer rotation members and a pressing force generating means to produce a pressing force for pressing the friction clutch according to the differential rotation. CONSTITUTION:A can means 18 operated to develop a thrust when the relative rotation of both rotation members 11 and 13 reaches a specified value, and a thrust transmission means 19 for transmitting a thrust from the cam means 18 to one of a friction clutch 10b are provided. Then the pressing force from a pressing force generating means 10a to the friction clutch 10b and the thrust from the cam means 18 are made in the same direction to each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving force transmission device which is interposed between a pair of coaxially supported rotary members to transmit torque between the rotary members.

[0002]

2. Description of the Related Art As one type of such driving force transmission device, as disclosed in Japanese Patent Laid-Open No. 63-240429,
The frictional engagement force is provided between the inner and outer rotary members coaxially and relatively rotatably arranged and actuated by the relative rotation of the both rotary members to generate a frictional engagement force for connecting the two rotary members so that torque can be transmitted. A friction clutch that increases or decreases the frictional engagement force according to the axial pressing force, and an axial pressing force that is disposed between the both rotary members and that corresponds to the relative rotation of the both rotary members to generate the same pressing force. There is a structure provided with a pressing force generating means for applying to the one side of the friction clutch via an operating piston.

In this type of driving force transmission device,
When relative rotation (differential rotation) occurs between both rotary members, pressure corresponding to the differential rotation speed is generated in the pressing force generating means. This pressure presses the friction clutch via the actuating piston and generates a friction engagement force that couples both rotary members to the clutch in a torque-transmittable manner. The frictional engagement force is proportional to the differential rotation speed, and torque proportional to the differential rotation speed is transmitted between the two rotary members from one to the other. Therefore, the driving force transmission device functions as a connecting mechanism between the driving side rotation member and the driven side rotation member in one driving force transmission system path of the four-wheel drive vehicle, and at the same time, between the driving side and driven side rotation members It also functions as a differential limiting mechanism between the side rotating members or between both driven side rotating members.

Further, in this type of driving force transmission device, when the relative rotation between the two rotary members is large, such as when the vehicle falls into a bad road, the friction heat generated by the friction clutch is high, and this state If it continues for a long time, the friction clutch may be burned out. Therefore, in order to prevent such a burnout of the friction clutch, a drive provided with a lock-up mechanism that firmly engages the friction clutch when the relative rotation of both rotary members reaches a predetermined value and brings the friction clutch into a coupled state. A force transmission device is proposed in Japanese Patent Laid-Open No. 1-261553. The driving force transmitting device is the same as the driving force transmitting device of the above type, and is provided with a cam means that is activated when the relative rotation of both rotating members reaches a predetermined value to generate a thrust force. It has a V-shaped cam groove and a ball that engages with the cam groove.

[0005]

By the way, in the above-mentioned drive force transmission device, the thrust generated from the cam means is transmitted to the other side of the friction clutch, and this thrust is transmitted through the working piston. The friction clutch is brought into the engaged state by overcoming the pressing force from the pressing force generating means applied from one side. That is, assuming that the pressing force from the working piston to one side of the friction clutch is FP and the thrust from the cam means to the other side of the friction clutch is FC, the condition for coupling the friction clutch is FC> FP and the friction clutch is coupled. To achieve this, a large thrust force that overcomes the pressing force of the working piston is required. For this reason, it is necessary to set a small inclination angle of the inclined cam surface forming the cam means to generate a large thrust, but if the inclination angle of the cam surface is set small, the cam groove and the ball are likely to bite. At the same time, the cam normal force becomes large and the strength of the cam means becomes a problem. Therefore, it is an object of the present invention to address such issues.

[0006]

SUMMARY OF THE INVENTION The present invention provides a driving force transmission device of the type described above, which includes cam means for actuating to generate thrust when the relative rotation of the two rotating members reaches a predetermined value, and the same cam. It is characterized in that thrust transmitting means for transmitting the thrust from the means in the same direction as the acting direction of the pressing force of the working piston is provided on one side of the friction clutch.

[0007]

In the driving force transmission device having such a structure, when the relative rotation of both rotary members reaches a predetermined value, the thrust force generated by the cam means is transmitted to one side of the friction clutch. Since the transmission direction of the thrust to the friction clutch is the same as the pressing force from the working piston, the thrust required is extremely small as compared with the above-described conventional driving force transmission device.
Therefore, the inclination angle of the inclined cam surface constituting the cam means can be set to be large, so that the cam means can be prevented from biting, and the cam normal force can be made small to increase the strength of the cam means. Can be improved.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of a driving force transmission device according to the present invention. As shown in FIG. 4, the driving force transmission device 10 is arranged on the rear wheel side power transmission path of a real-time four-wheel drive vehicle. In this four-wheel drive vehicle, the front wheels are always driven and the rear wheels are driven when necessary. The transaxle 22 mounted on one side of the engine 21 is equipped with a transmission and a transfer, and the power from the engine 21 is supplied to the axle shaft. 23 to drive the front wheels 24 and output to the first propeller shaft 25. The first propeller shaft 25 is the driving force transmission device 10.
When the two shafts 25, 26 can transmit torque, power is output to the axle shaft 28 via the rear differential 27 and the rear wheels 29 are driven.

The driving force transmission device 10 includes an outer case 11 and an end cover 12 which are outer rotating members, and a pressing force generating means 10a and a friction clutch 10b in an annular working chamber which is composed of an inner shaft 13 which is an inner rotating member. There is. The outer case 11 includes an inward flange portion 11b at an inner end of a tubular portion 11a having a predetermined length, and an end cover 12 is screwed into an outer end opening of the tubular portion 11a. The inner shaft 13 has an outward flange 14 attached to the outer periphery of the intermediate portion of a stepped cylindrical portion 13a having a predetermined length, and the outer spline portion 14a extending in the axial direction on the outer periphery of the outward flange 14.
A friction clutch 10b is attached to the. Further, the pressing force generating means 10a includes the end cover 12 and the friction clutch 1.
It is arranged between one side of 0b.

In the inner shaft 13, the second propeller shaft 26 is spline-fitted and fixed to an axially extending inner spline portion provided on the inner circumference of the inner end side of the tubular portion 13a. Of the outer case 11 is liquid-tightly and rotatably fitted and supported in the inner hole of the inward flange portion 11b of the outer case 11, and the outer end thereof is fitted in the inner hole of the end cover 12 in a liquid-tight manner. In the outer case 11, the rear end of the first propeller shaft 25 is fixed.

The pressing force generating means 10a is a working piston 15
And the rotor 16, and the friction clutch 10b is provided laterally.
To form a clutch housing chamber R1. The friction clutch 10b is of a wet multi-plate clutch type and includes a large number of clutch plates 17a and clutch discs 17b. Each clutch plate 17a has an outer spline portion fitted to a spline portion 11c provided on the inner circumference 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 clutch disc 17b has an inner spline portion fitted to the outer spline portion 14a of the outward flange 14 and is located between the clutch plates 17a, and is assembled to the outward flange 14 so as to be integrally rotatable and axially movable. It is attached. A predetermined amount of clutch oil and air is sealed in the storage chamber R1 of the clutch plate 17a and the clutch disc 17b.

The actuating piston 15 constituting the pressing force generating means 10a is liquid-tightly integrally rotatable with the inner circumference of one end side of the cylindrical portion 11a of the outer case 11 and slidable in the axial direction, and with respect to the inner shaft 13. Of the friction clutch 10b, they are mounted on the outer periphery of the friction clutch 10b so as to be liquid-tightly rotatable and slidable in the axial direction. As shown in FIGS. 1 and 2, the rotor 16 has an annular boss portion 16a.
Two vane portions 16b extending in the radial direction are provided at positions 180 ° apart from each other on the outer periphery of the inner peripheral surface of the inner shaft 13 and are fitted to the outer peripheral portion of the cylindrical portion 13a of the inner shaft 13 by the annular boss portion 16a. It is assembled so that it can rotate together. The rotor 16 is formed to have substantially the same thickness as the depth of the annular recess 15a provided on one side of the working piston 15, and is fitted in the annular recess 15a.

The end cover 12 is fluid-tightly fitted to the outer periphery of the cylindrical portion 13a of the inner shaft 13 so as to be slidable and rotatable in the axial direction, and is screwed to the outer case 11 so as to be movable back and forth. It is liquid-tight. The end cover 12 is adjusted in position in the axial direction and fixed to the outer case 11 by caulking, and the side surface 12 thereof is provided.
At a, it contacts the annular outer edge surface on one side of the working piston 15,
The side surface 12a and the annular recess 15a of the working piston 15 form a fluid chamber in which the rotor 16 is located. A highly viscous fluid such as silicone oil is enclosed in this fluid chamber, and the rotor 16 makes its outer periphery of the vane portion 16b liquid-tightly contact with the inner periphery of the annular recess 15a so that the fluid chamber has two retention chambers. It is divided into R2.

In the driving force transmission device 10, the outward flange 14 is mounted on the inner shaft 13 so as to be rotatable and slidable in the axial direction.
A cam means 18 is provided between 14 and the friction clutch 1
0b and the outward flange 14 are provided with thrust transmitting means 19. As shown in FIG. 3, the cam means 18 is composed of a cylindrical cam pin 18a fitted in the fitting recess 13b of the inner shaft 13 and a V-shaped cam groove 18b formed in the outward flange 14. A plurality of cylindrical portions 13a are provided in the circumferential direction of the cylindrical portion 13a. Further, a disc spring 13c is assembled on the cylindrical portion 13a of the inner shaft 13 on the side opposite to the site where the cam means 18 is arranged, and the disc spring 13c causes the outward flange 14 to move the cam flange 1 with a predetermined force.
It is urging to the 8 side. With this configuration, the cam means 18
When the relative rotation between the outer case 11 and the inner shaft 13 is less than a predetermined value, the outer case 11 is in a non-operating state and holds the outward flange 14 integrally rotatable with the inner shaft 13, and the relative rotation is predetermined. When it exceeds a value, it operates to generate thrust, and the thrust causes the outward flange 14 to slide in the axial direction against the disc spring 13c.

The thrust transmitting means 19 is the pressure plate 1
The pressure plate 19a is loosely fitted on the boss portion 14b of the outward flange 14 so that one end portion of the outer periphery fits into the recess 15b of the working piston 15 and faces one side of the friction clutch 10b. is doing. The pressure plate 19a is loosely fitted on the boss portion 14b of the outward flange 14, and is retained by a nut 19c screwed onto the boss portion 14b via a thrust bearing 19b. As a result, the pressure plate 19a is rotatable with respect to the outward flange 14 and moves integrally with the flange 14 in the axial direction.

In the driving force transmission device 10 having such a configuration, torque is transmitted when relative rotation occurs between the first and second propeller shafts 25 and 26. That is,
When relative rotation occurs between these shafts 25 and 26,
An outer case 11, an end cover 12, and an operating piston 15 that are integrally rotatably assembled to the first propeller shaft 25, and an inner shaft 13 and a rotor 16 that are integrally rotatably assembled to the second propeller shaft 26. Relative rotation occurs between.

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 rotation speed, and the retention chamber R2 sequentially shifts relative to the circumferential direction. Due to the flow resistance, a pressure distribution in which the pressure is gradually increased from the downstream end of the vane portion 16b toward the upstream end of the next vane portion 16b is generated therein. The pressure increasing portion of this pressure distribution increases in proportion to the differential rotation speed, and presses the working piston 15 in the axial direction. As a result,
The working piston 15 presses the friction clutch 10b to frictionally engage each clutch plate 17a with the clutch disc 17b via the clutch oil.

In this case, both propeller shafts 25, 26
If the relative rotation between them is less than a predetermined value, the cam means 18 is inactive. Therefore, the friction clutch 10b is frictionally engaged only by receiving the pressing force from the working piston 15, and transmits the torque proportional to the differential rotation speed from the outer case 11 to the inner shaft 13, so that the vehicle is in the four-wheel drive state. Become. Further, in this four-wheel drive state, differential rotation of the front and rear wheels is allowed, and the occurrence of the tight corner braking phenomenon is prevented. On the other hand, when the relative rotation between the propeller shafts 25 and 26 becomes a predetermined value or more and the transmission torque in the friction clutch 10b overcomes the spring force of the disc spring 13c, the cam means 18 operates to generate thrust, and the outward flange. 1
4 is slid in the axial direction against the disc spring 13c. Therefore, the pressure plate 19a moves in the axial direction integrally with the flange 14 and presses the friction clutch 10b together with the working piston 15. As a result, the friction clutch 10
b is firmly friction-engaged and coupled to each other, so that the outer case 11 and the inner shaft 13, and thus both propeller shafts 2
5 and 26 are integrally connected to each other to improve the ability of the vehicle to escape from a bad road.

As described above, in the driving force transmission device 10, when the relative rotation between the outer case 11 and the inner shaft 13 reaches a predetermined value, the thrust generated by the cam means 18 is transmitted to one side of the friction clutch 10b. However, since the direction of transmission of this thrust to the friction clutch 10b coincides with the pressing force from the working piston 15, a very small thrust is sufficient as compared with the above-mentioned conventional driving force transmission device. Therefore, the inclination angle of the inclined cam surface of the cam groove 18b forming the cam means 18 can be set to a large value.
It is possible to prevent the occurrence of biting in the cam and to reduce the cam normal force.
The strength in can be improved.

[Brief description of drawings]

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 front view of a rotor that constitutes the driving force transmission device.

FIG. 3 is a cross-sectional plan view showing cam means constituting the driving force transmission device.

FIG. 4 is a schematic configuration diagram of a four-wheel drive vehicle that employs the same driving force transmission device.

[Explanation of symbols]

10 ... Driving force transmission device, 10a ... Pressing force generating means, 10
b ... Friction clutch, 11 ... Outer case, 12 ... End cover, 13 ... Inner shaft, 13c ... Disc spring, 14
... outward flange, 15 ... working piston, 16 ... rotor,
16b ... Vane part, 17a ... Clutch plate, 17b
... clutch disc, 18 ... cam means, 18a ... cam pin, 18b ... cam groove, 19 ... thrust transmitting means, 19a ... pressure plate, 25, 26 ... propeller shaft, R
1 ... Clutch accommodating chamber, R2 ... Retaining chamber (fluid chamber)

Claims (1)

[Claims] 1. A clutch accommodating chamber provided between both inner and outer rotating members which are coaxially and relatively rotatable with each other, and is operated by relative rotation of these both rotating members to connect both rotating members so that torque can be transmitted. A friction clutch that generates a frictional engagement force and increases or decreases the frictional engagement force according to an axial pressing force that is applied, and an axial direction that is disposed between the both rotary members and that corresponds to the relative rotation of the two rotary members. In the drive force transmission device having a pressing force generating means for generating the pressing force of the rotating clutch and applying the pressing force to one side of the friction clutch via the actuating piston, the relative rotation of both rotary members reaches a predetermined value. And a thrust transmitting means for transmitting the thrust from the cam in the same direction as the acting direction of the pressing force of the working piston on one side of the friction clutch. Drive force transmission apparatus being characterized in that disposed.