JPH0519678U - Driving force transmission device - Google Patents

Abstract

(57) [Abstract] [Purpose] In a driving force transmission device that transmits torque by engaging a friction clutch with fluid pressure generated by relative rotation of a rotor provided in a viscous fluid chamber, the viscosity decreases due to a rise in temperature of the viscous fluid. It is possible to prevent a decrease in the generated fluid pressure due to the above, and to correct a decrease in the torque transmission characteristic of the viscous fluid at a high temperature. [Structure] A peripheral wall of a viscous fluid chamber R2 is constituted by a ring 17 made of a shape memory alloy, and at a predetermined high temperature, the diameter of the ring 17 is reduced by a temperature action, and the inner periphery of the ring 17 and the vane portion 15b of the rotor 15 are formed. The clearance C between the outer circumferences has been reduced.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a driving force transmission device that is interposed between two rotating members that are coaxially supported and that transmits torque between these two members.

[0002]

[Prior art]

 Such a driving force transmitting device is interposed between both rotating members which are coaxially supported with each other, and when both these members rotate relative to each other, these two members are coupled so that torque can be transmitted to each other, so that the driven side rotating member is driven. It is roughly divided into those used as a connecting mechanism for controlling the rotation and those used as a differential limiting mechanism for limiting the rotation difference between these two members. The former coupling mechanism is mainly installed in one power transmission path 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 disclosed in Japanese Patent Application Laid-Open No. 63-240429, a conventional driving force transmission device is arranged between both inner and outer rotating members that are coaxially and relatively rotatable. A friction clutch that operates by relative rotation of both rotating members to generate a frictional engaging force that connects the two rotating members so that torque can be transmitted, and that increases or decreases the frictional engaging force according to an axial pressing force applied, A pressing force generating means for generating an axial pressing force corresponding to the relative rotation of both rotating members and applying the pressing force to the friction clutch is provided, and the pressing force generating means is provided between the rotating members. An operating piston that is tightly slidable in the axial direction and is integrally rotatably mounted on the outer rotating member and faces one side of the friction clutch; and a shaft formed between the outer rotating member and the operating piston. A fluid chamber having a predetermined interval in the direction in which a viscous fluid is enclosed, and one or a plurality of vanes extending radially outward are provided so as to be integrally rotatable with the inner rotary member in the fluid chamber. There is a driving force transmission device including a rotor that generates fluid pressure in the fluid chamber during rotation.

In this type of driving force transmission device, when relative rotation occurs between both rotary members, pressure corresponding to the differential rotation speed is generated in the pressing force generation means. This pressure presses the friction clutch to generate a frictional engagement force that couples both rotary members to the same clutch so that torque can be transmitted. Such 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 drive force transmission device functions as a connecting mechanism between the drive-side rotating member and the driven-side rotating member in one power transmission system path of the four-wheel drive vehicle, and also between the drive-side and driven-side rotating members. It also functions as a differential limiting mechanism between the side rotating members or between both driven side rotating members.

[0005]

[Problems to be solved by the device]

 By the way, in this type of driving force transmission device, since the pressing force is generated by the pressure of the viscous fluid sealed in the fluid chamber, it occurs when the viscosity of the viscous fluid changes due to temperature change. As the pressure changes, the pressing force also changes, which causes a change in the transmission torque. Usually, the viscosity of viscous fluid decreases as the temperature rises, and as a result, the generated pressure decreases and the transmission torque decreases. Therefore, in this type of driving force transmission device, there is a problem that the torque transmission characteristic changes due to the temperature change of the viscous fluid. Therefore, the object of the present invention is to solve such a problem.

[0006]

[Means for Solving the Problems]

 The present invention is characterized in that, in the driving force transmission device of the above-mentioned type, the annular wall forming the outer circumference of the fluid chamber is formed of a material that can be reduced in diameter and expanded by temperature change. In the present invention, a shape memory alloy, a bimetal or the like is preferably used as the material forming the annular wall.

[0007]

[Operation and effect of the device]

 In the driving force transmission device having such a structure, when the viscous fluid in the fluid chamber becomes high in temperature, the annular wall forming the fluid chamber sharply decreases at a predetermined temperature or gradually decreases in accordance with the temperature change, and the annular wall The clearance between the inner circumference of the rotor and the outer circumference of the vane part of the rotor is reduced. As a result, the pressure generated in the fluid chamber increases in accordance with the reduction in the clearance, and the decrease in the generated pressure due to the decrease in the viscosity of the viscous fluid is corrected. Therefore, according to the driving force transmission device, a decrease in torque transmission due to a decrease in viscosity of the viscous fluid due to an increase in temperature is eliminated or suppressed, and stable torque transmission characteristics are obtained regardless of temperature change.

[0008]

【Example】

 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 system 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 transmitted to the axle. It outputs to the shaft 23 to drive the front wheels 24, and also outputs to the first propeller shaft 25. The first propeller shaft 25 is connected to the second propeller shaft 26 via the driving force transmission device 10. When torque can be transmitted to both shafts 25, 26, power is transmitted to the axle shaft 28 via the rear differential 27. It is output and the rear wheel 29 is driven.

The driving force transmission device 10 has the same basic configuration as that of the driving force transmission device disclosed in the Japanese Patent Application No. 2-79837 filed by the present applicant. The outer casing 11 and the end are outer rotating members. A pressing force generating means 10a and a friction clutch 10b are provided in an annular working chamber including a cover 12 and an inner shaft 13 which is an inner rotating member. The outer case 11 is provided with an inward flange portion 11b at one end of a tubular portion 11a having a predetermined length, and an end cover 12 is screwed into the other end opening of the tubular portion 11a.

The inner shaft 13 is provided with an outward flange portion 13b on the outer periphery of the middle portion of a stepped cylindrical portion 13a having a predetermined length, and an outer spline portion 13c extending in the axial direction is formed on the outer periphery of the flange portion 13b. .. In the inner shaft 13, one end of the cylindrical portion 13a is fitted in the inner hole of the inward flange portion 11b of the outer case 11 and the other end is fitted in a liquid tight and rotatable manner in the inner hole of the end cover 12. Have been supported. The inner shaft 13 has its inner spline portion fitted and fixed to the spline at the tip of the second propeller shaft 26, and the outer case 11 is fixed to the rear end of the first propeller shaft 25.

The pressing force generating means 10a includes an operating piston 14 and a rotor 15, and the friction clutch 10b is of a wet multi-plate clutch type, and includes a large number of clutch plates 16a and clutch discs 16b. Each clutch plate 16a has a spline portion on the outer periphery thereof 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 clutch disc 16b has an inner spline portion fitted to the outer spline portion 13c of the inner shaft 13 and is positioned between the clutch plates 16a, and is assembled to the shaft 13 so as to be integrally rotatable and axially movable. It is attached. A predetermined amount of clutch oil and gas is sealed in the accommodating chamber R1 of the clutch plate 16a and the clutch disc 16b.

The actuating piston 14 constituting the pressing force generating means 10 a is liquid-tightly rotatable integrally with the inner circumference of the one end side of the cylindrical portion 11 a of the outer case 11 and slidable in the axial direction. Are mounted on the outer periphery thereof in a liquid-tight manner so as to be rotatable in a liquid-tight manner and slidable in the axial direction, and abut on the clutch plate 16a at the right end in the figure on the other side surface.

As shown in FIGS. 1 and 2, the rotor 15 is provided with three vane portions 15b extending in the radial direction at portions of the outer circumference of the annular boss portion 15a that are equidistant from each other. Is fitted to the outer circumference of the cylindrical portion 13a of the inner shaft 13, and is integrally rotatably assembled to the shaft 13. The rotor 15 is formed to have a width substantially the same as the axial width of the annular storage chamber provided between the working piston 14 and the end cover 12, and is fitted in the storage chamber. The end cover 12 is fluid-tightly fitted to the outer periphery of the one end side of the tubular portion 13a of the inner shaft 13 so as to be slidable and rotatable in the axial direction, and screwed to the outer case 11 so as to be capable of advancing and retreating. It is dense. The end cover 12 is adjusted in position in the axial direction and fixed to the outer case 11 by caulking means, and a predetermined distance is maintained between one side surface 12a thereof and one side surface 14a of the working piston 14. An annular storage chamber is formed. A predetermined amount of highly viscous fluid such as silicon oil and air are enclosed in this accommodating chamber, and the vane portion 15b of the rotor 15 divides the accommodating chamber into three fluid chambers R2.

In the present embodiment, the vane portion 15b forming the rotor 15 is formed asymmetrically in the rotational direction, and its side surface 15c is formed in a convex shape and the other side surface 15d is formed in a concave shape. There is. The side surface 15c of the vane portion 15b gradually extends away from the outer peripheral surface of the receiving chamber, which is closest to the outer peripheral surface of the receiving chamber, and extends in a circular arc shape along the outer peripheral surface for a predetermined length. There is. Further, the other side surface 15d of the vane portion 15b is gradually recessed from the tip portion thereof toward the annular boss portion 15a, and is formed in a shape having a recess at an intermediate portion between the vane portion 15b and the boss portion 15a. In the rotor 15, the arrow A direction in FIG. 2 is set to the forward rotation direction during relative rotation, and the arrow B direction is set to the reverse rotation direction during relative rotation.

Thus, in this embodiment, the shape memory alloy ring 17 is fitted to the peripheral portion of the storage chamber. As shown in FIG. 2, the ring 17 is a ring having an end, and has a characteristic that when it reaches a predetermined high temperature, it is deformed and its diameter is reduced. Therefore, the ring 17 contracts when the viscous fluid reaches a predetermined high temperature, and reduces the outer diameter of the storage chamber as shown in FIG. 3 (a).

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 the shafts 25 and 26 rotate relative to each other, the outer case 11, the end cover 12, the operating piston 14, and the second propeller shaft 26, which are integrally rotatable with the first propeller shaft 25, are assembled. Relative rotation occurs between the inner shaft 13 and the rotor 15 which are integrally rotatably mounted on the rotor. Therefore, in the pressing force generating means 10a, the viscous fluid in the fluid chamber R2 is forced to flow at a speed proportional to the relative rotational speed, and the flow resistance is increased in the fluid chamber R2 that sequentially shifts in the circumferential direction. Due to the above, a pressure distribution in which the pressure is gradually increased from the downstream end of the vane portion 15b toward the upstream end of the next vane portion 15b is generated. The pressure-increase portion of this pressure distribution increases in proportion to the differential rotation speed, and presses the working piston 14 in the axial direction.

As a result, the working piston 14 presses the friction clutch 10b to frictionally engage the clutch plates 16a and the clutch disc 16b with each other via the 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 13, 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 the tight corner breaking phenomenon is prevented.

By the way, when the rotor 15 in the drive force transmission device 10 normally rotates in the direction of the arrow A, the air existing in the fluid chamber R2 enters the recess of the vane portion 15b as shown in the area A1 in FIG. It stays (indicated by dots) and the moving area of the viscous fluid indicated by the arrow becomes longer. On the other hand, during reverse rotation of the rotor 15 in the direction of arrow B, the air stays in the arcuate portion of the vane portion 15b (indicated by dots) as indicated by the area B1 in FIG. The moving area of the fluid is shortened. As a result, the generated pressure in the fluid chamber R2 is large when the rotor 15 rotates forward and decreases when it rotates in the reverse direction, and the generated pressure differs depending on the length of the moving region of the viscous fluid. The pressing force against 14 is large during forward rotation, that is, when transmitting positive torque, and is small during reverse rotation, that is, during transmitting reverse torque.

In the driving force transmission device 10, the ring 17 has a large diameter as shown in FIGS. 2 and 3 (a) when the temperature of the viscous fluid is lower than the predetermined high temperature. The clearance C between the outer periphery of each vane portion 15b of 15 is kept large. On the other hand, when the viscous fluid reaches a predetermined high temperature, the ring 17 is deformed and its diameter is reduced, so that the clearance C becomes small as shown in FIG. When the clearance C becomes small, the pressure leak from the high pressure side to the low pressure side is restricted via the clearance C, so that the fluid pressure generated in the fluid chamber R2 becomes large, and the viscosity is decreased due to the temperature rise of the viscous fluid. To compensate for the decrease in fluid pressure. As a result, stable torque transmission characteristics can be obtained even at high temperature of the viscous fluid.

[Brief description of drawings]

FIG. 1 is a sectional view of a driving force transmission device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the same driving force transmission device taken along line 2-2 in FIG.

FIG. 3 is a cross-sectional view showing a change of a ring in 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, 14 ... working piston,
15 ... Rotor, 15b ... Vane part, 16a ... Clutch plate, 16b ... Clutch disc, 17 ... Ring, 2
5, 26 ... Propeller shaft, C ... Clearance, R2
… Fluid chamber.

Claims (1)

[Scope of utility model registration request] 1. A frictional engagement force which is disposed between both inner and outer rotating members coaxially and relatively rotatably positioned and which is actuated by relative rotation of these both rotating members to couple the both rotating members so that torque can be transmitted. And a friction clutch that increases or decreases the friction engagement force according to the axial pressing force applied,
And a pressing force generating means for generating a pressing force in the axial direction according to the relative rotation of the two rotating members to apply the same pressing force to the friction clutch, the pressing force generating means being provided between the rotating members. A working piston that is liquid-tightly slidable in the axial direction and integrally rotatably mounted on the outer rotating member and faces one side of the friction clutch; and an axial direction formed between the outer rotating member and the working piston. A fluid chamber in which a viscous fluid is sealed at a predetermined interval, and one or more vanes extending radially outward. When the fluid chamber is integrally rotatably assembled to the inner rotating member, In a driving force transmission device configured by a rotor that generates a fluid pressure in the fluid chamber, an annular wall forming a diameter outer circumference of the fluid chamber is formed of a material that can be reduced in diameter and expanded by temperature change. Drive characterized by Transmission device.