JPH0730997Y2 - Power transmission mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of use) The present invention is a power transmission mechanism that is disposed between a pair of rotating members that are coaxially and relatively rotatable and that transmits power between these two members. Regarding

(Prior Art) Such a power transmission mechanism is disposed between a driving side rotation member and a driven side rotation member, and when these both members relatively rotate, these two members are connected to each other so that power can be transmitted to the driven side rotation member. A member used as a connecting mechanism for driving members, a driving-side driven member, a driven-side rotating member, both driving-side rotating members, or both driven-side rotating members. Are connected to each other so as to be able to transmit power to each other, and are roughly classified into those used as a differential limiting mechanism for limiting the rotation difference between these two members. The former coupling mechanism is mainly arranged on one power transmission path in a real-time four-wheel drive vehicle, and the latter differential limiting mechanism is mainly arranged on each differential in the vehicle.

Therefore, as a conventional power transmission mechanism, Japanese Patent Laid-Open No. 63-24042
As disclosed in Japanese Patent Laid-Open No. 9-90, it is arranged between a pair of rotating members that are coaxially and relatively rotatable, and is operated by relative rotation of both rotating members to connect both rotating members so that power can be transmitted. Generating frictional engagement force and increasing / decreasing the frictional engagement force according to the applied pressing force, and generating frictional force by generating pressing force according to relative rotation of both rotary members. Means for applying a pressing force to the means, the pressing force generating means being fluid-tightly slidable between the rotating members in the axial direction and integrally rotatable with one of the rotating members so that the friction A fluid chamber in which a viscous fluid is enclosed is formed between the working piston facing the engaging force generating means and the one rotating member so as to be integrally rotatable with a predetermined space in the axial direction between the working piston and the working piston. Half retainer There is a power transmission mechanism including one or a plurality of vane portions extending in the radial direction and a rotor integrally assembled with the other rotating member in the fluid chamber.

In this type of power transmission mechanism, when a relative rotation occurs between both rotary members, an operating piston and a retainer that are integrally rotatable with one rotary member and a rotor that is integrally assembled with the other rotary member. Relative rotation occurs between and, viscous fluid in the viscous fluid sealing chamber partitioned by the vane part of the rotor of the fluid chamber is forced to flow, and pressure is generated in the sealing chamber due to flow resistance. . 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 to press the frictional engagement force generating means, and the frictional engagement force for connecting both rotating members to the same means so that power can be transmitted. The frictional engagement force is proportional to the differential rotation speed, and the power proportional to the differential rotation speed is transmitted between the two rotary members from one to the other. Therefore, the power transmission mechanism functions as a coupling mechanism between the drive-side rotating member and the driven-side rotating member in one power-transmitting system path of the four-wheel drive vehicle and rotates between the drive-side and driven-side rotating members and both drive-side rotating members. It also functions as a differential limiting mechanism between members or between both driven side rotating members.

(Problems to be solved by the invention) By the way, when the power transmission mechanism of the above-mentioned type is adopted as the connection mechanism of the four-wheel drive vehicle, a slight differential rotation speed is generated between both rotary members even during steady running. Occurs frequently and power is transmitted between the two rotary members, so that a drag phenomenon often occurs on one side of the front and rear wheels, which deteriorates fuel consumption and accelerates tire wear. Further, when a large power transmission is generated for a long time such as when the vehicle is in a stuck state, there is a risk that seizure or other burnout may occur in the friction engagement force generating means. Therefore, an object of the present invention is to address the above-mentioned problems.

(Means for Solving the Problems) In the power transmission mechanism of the type described above, the present invention applies a predetermined pressing force to the operating piston with a spring member to generate the operating piston by the pressing force generating means. The spring member is separated from the frictional engagement force generating means until the pressing force reaches a predetermined value, and the spring member is used as the spring member for increasing the pressing force to the working piston when a predetermined temperature is reached. .

As the spring member used in the present invention, there is a spring member made of a shape memory alloy whose shape is deformed when the temperature reaches a predetermined temperature to increase the spring constant.

(Operation and Effect of the Invention) According to this configuration, since the frictional engagement force generating means is separated from the working piston, when the differential rotation speed between both rotary members is small, the frictional engagement force generating means between both rotary members is small. There is no power transmission,
When the differential rotation speed between both rotating members becomes a predetermined value or more, the pressing force generated by the pressing force generating means becomes a predetermined value or more, and the working piston presses the frictional engagement force generating means to cause a difference between both rotating members. Power is transmitted. Further, when the frictional engagement force generating means becomes high in temperature and the spring member reaches a predetermined high temperature, the pressing force on the operating piston increases, and the spring member presses the operating piston against the pressing force generated by the pressing force generating means. Then
The working piston is separated from the frictional engagement force generating means.

Therefore, during steady running of a vehicle with a small differential rotation speed between both rotary members, there is no power transmission between both rotary members, and dragging phenomenon does not occur on one side of the front and rear wheels, which reduces fuel consumption and tires. Premature wear is prevented. Also, when the vehicle falls into a stuck state and a large amount of power is transmitted between the rotating members for a long time, the frictional engagement force generating means is released from the pressing force of the working piston, causing seizure of the means and other burnouts. Can be prevented.

(Embodiment) The first embodiment of the present invention will be described below with reference to the drawings.
An embodiment of the power transmission mechanism according to the present invention is shown in the drawings. As shown in FIG. 3, the power transmission mechanism 10 is arranged in the rear-wheel power transmission system of a real-time four-wheel drive vehicle.

In the 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 has a transmission and a transfer, and outputs power from the engine 21 to the axle shaft 23. Drive the front wheels 24 and output to the first propeller shaft 25. The first propeller shaft 25 is connected to the second propeller shaft 26 via the power transmission mechanism 10. If both shafts 25, 26 can transmit power, the power is transmitted via the rear differential 27 to the axle shaft.
It is output to 28, and the rear wheel 29 is driven.

Thus, the power transmission mechanism 10 has a pressing force generating means in the annular working chamber composed of the outer case 11 and the inner shaft 12.
10a and a frictional engagement force generating means 10b.

The outer case 11 is provided with an inward flange portion 11b at one end of a tubular portion 11a having a predetermined length, the other end of the tubular portion 11a is open, and a threaded portion 11c is formed on the inner circumference of the other end. The inner shaft 12 is provided with an outward flange portion 12b on the outer periphery of the intermediate portion of a stepped tubular portion 12a of a predetermined length, and an outer spline portion 12c extending in the axial direction is formed on the outer periphery of the flange portion 12b. An inner spline portion 12d extending in the axial direction is formed on the inner periphery of one end side of 12a. In the inner shaft 12, one end of the tubular portion 12a is fitted in the inner hole of the inward flange portion 11b of the outer case 11 in a liquid-tight and rotatable manner, and is assembled to the outer periphery of the other end of the tubular portion 12a. It is rotatably supported by the outer case 11 via the constituent members of the attached pressing force generating means 10a described later. The inner shaft 12 is fitted and fixed to the spline 26a at the tip portion of the second propeller shaft 26 at the inner spline portion 12d, and the outer case 11
Is fixed to the rear end of the first propeller shaft 25.

The pressing force generating means 10a is composed of an operating piston 13, a rotor 14 and a retainer 15, and the friction engagement force generating means 10b is of a wet multi-plate clutch type and has a large number of clutch plates 16.
And a clutch disc 17. Each clutch plate 16 has a protrusion on its outer periphery fitted into a groove 11d 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 clutch disc 17 has an inner peripheral raised portion fitted to the outer spline portion 12c of the inner shaft 12 and positioned between the clutch plates 16, and is assembled to the shaft 12 so as to be integrally rotatable and movable in the axial direction. It is attached. These clutch plates 16
A predetermined amount of clutch oil and gas is sealed in the storage chamber R1 of the clutch disc 17.

The working piston 13 that constitutes the pressing force generating means 10a is integrally rotatable with the inner circumference of the other end side of the tubular portion 11a of the outer case 11 and is slidable in the liquid-tight axial direction. The outer circumference of each of them is mounted so as to be rotatable and slidable in the axial direction, and one side surface 13a thereof abuts a pressing plate 18a described later. As shown in FIGS. 1 and 2, the rotor 14 has an outer circumference of the annular boss portion 14a of 180 ° with respect to each other.
It is provided with two vane portions 14b extending in the radial direction at distant portions, and is fitted integrally with the inner shaft 12 by being fitted to the outer periphery of the cylindrical portion 12a of the inner shaft 12 by the annular boss portion 14a. There is. The rotor 14 is formed to have substantially the same thickness as the depth of the annular recess 13b provided on the other side of the working piston 13, and is fitted in the annular recess 13b. The retainer 15 has a threaded portion 15a on the outer circumference on the other end side, and the inner shaft 12
Is fitted to the outer periphery of the other end of the cylindrical portion 12a in a liquid-tight manner so as to be slidable and rotatable in the axial direction, and the screw portion 15a of the outer case 11 can be moved forward and backward to the screw portion 11c of the outer case 11. It is screwed on and is liquid-tight. In the retainer 15, the position adjustment in the axial direction is performed so that the outer case 11
Is fixed to the annular outer edge surface 13c on the other side of the actuating piston 13 by one side surface 15b, and the one side surface 1b
5b and the annular recess 13b of the working piston 13 form a fluid chamber in which the rotor 14 is located. A predetermined amount of highly viscous fluid such as silicon oil is enclosed in this fluid chamber, and the rotor 14 makes the outer periphery of its vane portion 14b liquid-tightly contact the inner periphery of the annular recess 13b, and A minute gap is formed between both side surfaces and the other side surface 13b1 of the annular recess 13b and one side surface 15b of the retainer 14 to divide the fluid chamber into two retention chambers R2.

Thus, an annular pressing plate 18a is interposed between the clutch disc 17 at the rightmost end in the drawing and the working piston 13 which constitute the frictional engagement force generating means 10b, and the plate 18a is axially provided in the groove 11d of the outer case 11. It is assembled so that it can slide in any direction. Also, the inner periphery of the outer case 11 and the pressing plate 18
An annular spring member 18b is provided between the outer circumference of a and a snap ring 18c.
It is assembled through. The spring member 18b is made of a shape memory alloy whose shape is deformed and its spring constant is increased when a predetermined temperature is reached, and the pressing plate 18a is brought into contact with the working piston 13 via a snap ring 18c so that the piston 13 has a predetermined shape. The pressing force is applied. Thereby, the spring member 18b
Separates the frictional engagement force generating means 10b from the working piston 13 to release it from the pressing force. The working piston 13 and the pressing plate 18a are connected by a connecting pin 18d so that they can rotate integrally with each other.

In the power transmission mechanism 10 having such a configuration, even if the relative rotation occurs between the first and second propeller shafts 25 and 26, if the differential rotation speed between these shafts 25 and 26 is small, these shafts 25 and 26 will not rotate. , 26 is not transmitted, but torque is transmitted when the differential rotation speed between both shafts 25, 26 reaches a predetermined value. That is, when a relative rotation occurs between the shafts 25 and 26, the outer case 11, the working piston 13 and the retainer 15 that are integrally rotatably assembled to the first propeller shaft 25 and the second propeller shaft 26 are integrated. Relative rotation occurs between the rotatably mounted inner shaft 12 and rotor 14. Therefore, in the fluid chamber of the pressing force generating means 10a, the viscous fluid in the retention chamber R2 is forcibly flown at a speed proportional to the relative rotation speed, and flows in the retention chamber R2 that sequentially shifts in the circumferential direction. Due to the resistance, from the downstream end of the vane portion 14b to the next vane portion 14b.
A pressure distribution is generated in which the pressure is gradually increased toward the upstream end of the. The pressure increasing portion of this pressure distribution increases in proportion to the differential rotation speed, and presses the working piston 13 in the axial direction.

When the pressing force generated by the pressing force generating means 10a becomes larger than the pressing force from the spring member 18b, the working piston 1
Reference numeral 3 presses the frictional engagement force generating means 10b via the pressing plate 18a to frictionally engage each clutch plate 16 and the clutch disc 17 constituting the frictional engagement force generating means 10b via the clutch oil. As a result, in the frictional engagement force generating means 10b, the torque proportional to the differential rotation speed is transmitted from the outer case 11 to the inner shaft 12, and the vehicle is in the four-wheel drive state. Further, in this four-wheel drive state, differential rotation of the front and rear wheels is allowed, and the occurrence of a tire corner braking phenomenon is prevented. Further, in the power transmission mechanism 10, when the frictional engagement force generating means 10b reaches a predetermined high temperature, the spring member 18b is deformed to increase the pressing force against the working piston 13, and the means 10b is separated from the working piston 13. Release from pressing force. As a result, the frictional engagement of the frictional engagement force generating means 10b is released, and the temperature of the means 10b is prevented from further increasing. The spring member 18b returns to its original state when the temperature drops below a predetermined value. Therefore, in the power transmission mechanism 10, the drag phenomenon does not frequently occur on one side of the front and rear wheels during steady running of the vehicle, which deteriorates fuel efficiency and prematurely wears the tires. It is possible to prevent seizure of the generating means 10b and other burnouts.

[Brief description of drawings]

1 is a sectional view of a power transmission mechanism according to an embodiment of the present invention, FIG. 2 is a sectional view taken along the line II-II of FIG. 1, and FIG.
The figure is a schematic diagram of a vehicle that employs the same mechanism. DESCRIPTION OF SYMBOLS 10 ... Power transmission mechanism, 10a ... Pressing force generating means, 10b ... Friction engagement force generating means, 11 ... Outer case, 12 ... Inner shaft, 13 ... Working piston, 14 ... Rotor, 14b ... Vane section, 1
5 ... Retainer, 16 ... Clutch plate, 17 ... Clutch disc, 18b ... Spring member, 25, 26 ... Propeller shaft.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoshi Ashida 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Co., Ltd. (72) Inventor Shoji Yamamoto 1-1 1-1 Asahi-cho, Kariya-shi, Aichi Toyota Koki Co., Ltd. Within

Claims (1)

[Scope of utility model registration request] 1. A frictional engagement force, which is disposed between a pair of rotating members coaxially and relatively rotatably positioned, is actuated by relative rotation of these rotating members to couple the rotating members so that power can be transmitted. And a frictional force generating means for increasing / decreasing the frictional force according to the applied pressure force, and a pressure force for generating the pressure force according to the relative rotation of the two rotary members and imparting the force to the frictional force generation means. And a pressing means for generating the pressing force, which is liquid-tightly slidable in the axial direction between the rotary members and is integrally rotatable with one of the rotary members so as to face the frictional engagement force generating means. And a retainer that is integrally rotatably provided on the one rotating member and that forms a fluid chamber in which a viscous fluid is sealed at a predetermined interval in the axial direction between the operating piston and
A power transmission mechanism comprising one or a plurality of vane portions extending in the radial direction and a rotor integrally assembled with the other rotating member in the fluid chamber, wherein a spring member is provided for the working piston. When the pressing force is applied to the working piston to separate it from the friction engagement force generating means until the pressing force generated by the pressing force generating means reaches a predetermined value, and when the spring member reaches a predetermined temperature. A power transmission mechanism comprising a spring member for increasing a pressing force applied to the working piston.