JPH0277329A - Transfer device for four-wheel drive vehicle - Google Patents

Abstract

PURPOSE:To contrive to make both an actuator and clutch plates small in size to a great extent by permitting the pressing force of the actuator to be increased so as to transfer it owing to the principle of the lever. CONSTITUTION:In a transfer device 10 for a four-wheel drive vehicle, in case that the pressing force of an actuator 58 is applied to clutch plates 52, when a lever 56 is made to work with a fulcrum at No.1 recessed section 56b, with the point of force at No.2 recessed section 54, and with a projection 56d as the point of application pressing a sleeve 54 at the intermediate section of the lever, the lever 56 permits the pressing force of the actuator 58 to be increased so as to transfer it to the clutch plates 52 owing to the principle of the lever. By this constitution, the pressing force to be generated by the actuator 58 can therefore be made small, the actuator 58 can thereby be made small in size.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a transfer device for a four-wheel drive vehicle, and more particularly to a transfer device in which torque is distributed to front and rear wheels via friction elements.

(Prior Art) As a transfer device of this type for a four-wheel drive vehicle, there is a conventional transfer device disclosed in, for example, Japanese Patent Laid-Open No. 62-24072.

That is, the transfer device disclosed in the publication is as follows:
A second output shaft connected to the front wheel side is provided parallel to the output shaft connected to the rear wheel side, and a distribution mechanism consisting of a sprocket and a chain is provided between these output shafts and the second output shaft, Then, by tightening or releasing the friction element provided between the output shaft and the distribution mechanism, the second
Torque is distributed or cut off to the output shaft, thereby switching between four-wheel drive and two-wheel drive.

(Problem to be Solved by the Invention) However, in such a conventional transfer device for a four-wheel drive vehicle, the friction element that connects and releases the output shaft and the distribution mechanism is of a generally used drum type. A multi-plate clutch is used.

The above-mentioned drum-type multi-plate Kura-Sochi is equipped with a cylindrical drum surrounding the outside of the output shaft, and a clutch plate is provided inside the drum, and a clutch plate is formed continuously from the inner periphery of the drum. A piston constituting an actuator is fitted between the inner cylinder and the outer periphery of the inner cylinder, and the piston is hydraulically driven to suppress or release the clutch plate.

Therefore, since such a friction element has a clutch plate and a piston provided within the drum, the drum inevitably becomes larger, which in turn necessitates an increase in the diameter of the transfer device.

In addition, since the piston is fitted to the inner periphery of the drum, which has a larger diameter, the length of the seal at the fitting portion becomes longer.
Furthermore, the sealing performance of the piston is significantly reduced due to the fact that the roundness is deteriorated due to the increase in diameter, and furthermore, a sealing function is required on the inner and outer peripheries of the piston.

Furthermore, in order to prevent this deterioration of sealing performance, tightening allowances (shields) are added to the inner and outer circumferences of the piston.

- If the pressing force of the small member is increased, hysteresis increases when the piston moves, making it impossible to accurately drive the friction element relative to the control oil pressure.

SUMMARY OF THE INVENTION In view of these conventional problems, it is an object of the present invention to provide a transfer device for a four-wheel drive vehicle that can achieve miniaturization of friction elements and a reduction in the diameter of an actuator.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides an output shaft that outputs torque input from a power source to one of front wheels or rear wheels, and an output shaft that outputs torque input from a power source to one of the front wheels or the rear wheels. A transfer device for a four-wheel drive vehicle comprising a distribution mechanism that distributes the distribution to the other of the front wheels or the rear wheels via a friction element, wherein the friction element is connected to the output shaft by surrounding the outside of the output shaft and the distribution mechanism. a clutch plate disposed between the clutch plate, a sleeve axially movably fitted to the outside of the output shaft and capable of abutting against one side of the clutch plate in the axial direction, and a sleeve rotatable to the transfer case at one end. a lever that is provided with a fulcrum that can be supported, a force point that receives a pressing force at the other end, and a point of action that presses the sleeve in the axial direction at an intermediate portion; and an actuator that applies a pressing force to the force point of the lever. Establish and configure.

(Function) With the above configuration, in the transfer device for a four-wheel drive vehicle of the present invention, when the pressing force of the actuator is applied to the force point of the lever, the lever is rotated about the fulcrum at one end and The point of action of the clutch presses the sleeve, and this pressing force is transmitted to the clutch plate via the sleeve, so that the clutch plate is pressed into contact with the clutch plate.

Therefore, when the pressing force of the actuator is transmitted to the clutch plate via the lever, the pressing force of the actuator is increased and transmitted due to the principle of leverage of the lever, and this increased amount is generated by the actuator. The pressing force applied can be reduced.

Therefore, it is possible to reduce the diameter of the actuator, improving sealing performance, and since the actuator does not need to be arranged coaxially with the output shaft, the diameter of the clutch plate is restricted to the actuator. Since the clutch plate can be determined by considering only the diameter necessary for the fastening force, the diameter of the clutch plate can be significantly reduced.

(Example) Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 shows a transfer device 10 for a four-wheel drive vehicle showing one embodiment of the present invention, and reference numeral 12 denotes a transfer case 1.
A center drive shaft serving as an output shaft is rotatably supported by the center drive shaft 12 via a bearing 16. The right end of the center drive shaft 12 in the drawing is coupled via a coupling 18 to a propeller shaft 20 that is connected to a rear wheel side final reduction gear (not shown).

A cylindrical main shaft 22 is fitted to the outer periphery of the center drive shaft 12 for relative rotation, and
A first sprocket 24 is provided on the outer periphery of the main shaft 22.
are fitted with serrations.

Further, on the side of the center drive shaft 12,
A front drive shaft 26 is provided parallel to the center drive shaft 12, and the front drive shaft 26 has serrations in a hollow shaft 27 rotatably supported by the transfer case 14 via bearings 28, 28a. It is fitted through.

A second sprocket 30 is integrally formed on the outer periphery of the hollow shaft 27, and a chain 32 is wound between the second sprocket 30 and the first sprocket 24, and the main Torque is transmitted between the shaft 22 and the hollow shaft 27, that is, the front drive shaft 26.

The main shaft 22. 1st sprocket 2
4. Chain 32 and second sprocket 30 constitute a distribution mechanism 34.

A friction element 50 is provided between the center drive shaft 12 and the main shaft 22, and torque is distributed and cut off from the center drive shaft 12 to the distribution mechanism 34 by engaging and releasing the friction element 50.

The friction element 50 includes a multi-plate clutch plate 52, a sleeve 54 that presses the clutch plate 52, a lever 56 that transmits a pressing force to the sleeve 54, and an actuator 58 that applies a pressing force to the lever 56. It is roughly composed of:

The clutch plate 52 includes a large number of drive plates and driven plates arranged alternately. A driven plate is locked to the inner cylinder 62 side which is integrally fixed to the inner cylinder 62.

The sleeve 54 is slidably fitted onto the outer periphery of the boss portion 60a of the outer cylinder 60, and a portion of the sleeve 54 on the clutch plate 52 side is provided on one side of the clutch plate 52 in the axial direction (right side in the figure). A plurality of contactable protrusions 54a are provided at approximately equal intervals in the circumferential direction.

Further, a bearing 64 is fitted on the outer periphery of the fabric end in the figure where the lever 56 of the sleeve 54 is disposed, and a right end surface of the bearing 64 in the figure is fitted on the outer periphery of the outer race of the bearing 64. A covering retainer 66 is fitted.

As shown in FIG. 2, the lever 56 has an opening 56 in the center that is loosely fitted into the center drive shaft 12.
a, and a first recess 56b serving as a fulcrum at one end (upper end in the figure) and a second recess 56b serving as a point of effort at the other end (lower end in the figure).
A recess 56c is formed, and a protrusion 56d serving as a point of action is further formed at the peripheral edge of the opening 56a.

A pivot 68 supported by the transfer case 14 is rotatably fitted into the first recess 56b, and
A bushing rod 70 of the actuator 58 is rotatably fitted into the second recess 56c.

Further, the convex portion 56d is the first convex portion 56d. Second recess 56b, 5
A pair of convex portions 56d are provided in a direction perpendicular to the arrangement direction (vertical direction in FIG. 2) of the convex portions 6c (vertical direction in FIG. 2).
are in contact with the retainer 66, respectively.

The protrusion of the convex portion 56d is formed in a smooth arc shape, and even when the lever 56 rotates, the convex portion 56d remains on the retainer 66 approximately on the center line of the center drive shaft 12 in FIG. It is designed to be touched.

The actuator 58 is connected to the second recess 5 of the lever 56.
6c and is fixed to the transfer case 14, and a piston 58b that is slidably and fluid-tightly fitted to the cylinder 58a, constitutes a normal hydraulic cylinder device. Then, hydraulic pressure is supplied from the port 58C to the cylinder chamber 58d, thereby causing the piston 58b to protrude.

The bushing rod 70 is rotatably fitted into a recess formed at the protruding end of the piston 58b.

The sleeve 54 is pressed in the direction in which the clutch plate 52 is released (to the right in FIG. 1) by a spring 72 that is compressed to a distance of 1 m from the outer cylinder 60.

Further, in FIG. 1, 74 is a control lever.

With the above-described configuration, in the transfer device 10 of this embodiment, when hydraulic pressure is not supplied to the actuator 58, the piston 58b is retracted to the right in the figure, and the lever 56 is moved toward the sleeve 58 by the biasing force of the spring 72. The lever 56 is pushed in the direction shown in the figure through the lever 56, and the lever 56 is set at a position rotated counterclockwise.

Therefore, at this time, the clutch plate 52 is released from pressure and the friction element 50 is in a released state, and no torque is transmitted between the center drive shaft 12 and the main shaft 22.

Therefore, the engine power transmitted to the center drive shaft 12 is transmitted to the rear wheel final reduction gear FR only through the center drive shaft 12 to drive the rear wheels WR, as shown by the thick arrow in FIG. and becomes two-wheel drive.

Next, when hydraulic pressure is supplied to the actuator 58 to cause the piston 58b to protrude, a pressing force on the left side in the figure is applied to the second recess 56c of the lever 56 via the bushing rod 70.

Then, the lever 56 is rotated clockwise around the first recess 56b fitted in the pivot 68, and the protrusion 56d resists the biasing force of the spring 72 and moves the sleeve 5.
4 to the left in the drawing, the protrusion 54a presses the clutch plate 52 and presses the clutch plate 52, and the friction element 50 is brought into a fastened state.

Therefore, by fastening the friction element 50 in this manner, the torque of the center drive shaft 12 is distributed to the main shaft 22 via the friction element 50, and this distributed torque is transmitted from the main shaft 22 to the main shaft 22. 1 sprocket 24, chain 32. It is transmitted to the front wheel side final reduction gear F through the second sprocket 30 and the front drive shaft 26, and also drives the front wheel Wl- as shown by the bold line arrow in the fourth bacterium, resulting in a four-wheel drive state.

In addition, by appropriately controlling the hydraulic pressure supplied to the actuator 58, the pressure contact force of the clutch plate 52 can be adjusted, and the torque transmitted to the front wheels can be continuously changed according to the driving condition. , the friction element 50 can be used to limit the differential for the front wheels.

Furthermore, when the friction element 50 is completely engaged, the torque ratio distributed between the rear wheels and the front wheels is 50:50, while when the friction element 50 is completely released, the torque ratio is 100: It becomes O.

By the way, in the friction element 50 of this embodiment, the clutch plate 5
Since the clutch plate 52 and the actuator 58 are arranged axially separated from each other, the clutch plate 52 is provided independently, and its outer diameter is determined by considering only the pressing force required when the friction element 50 is fastened. can be determined, and a significant reduction in diameter can be achieved.

Further, when the pressing force of the actuator 58 is applied to the clutch plate 52, the suppressing force is transmitted via the lever 56, and the lever 56 has a first recess 56b as a fulcrum in the figure. The second recess 56c, which is located at the upper end and serves as a point of force to which the suppressing force is applied, is located at the lower end in the figure, and the convex portion 56d, which is the point of action that presses the sleeve 54, is located at the middle portion, so that the lever 56 This acts as a lever and increases the pressing force of the actuator 58 to push the sleeve 54
In other words, it is transmitted to the clutch plate 52.

Therefore, since the pressing force generated by the actuator 58 can be reduced, the actuator 5
It is possible to achieve a smaller diameter of 8, and thus a smaller size.

Further, by reducing the diameter of the actuator 58, the cylinder 58a and the piston 58b can be formed with high roundness, and the seal length between the cylinder 58a and the piston 58b can be significantly shortened. be able to.

Therefore, the sealing performance of the actuator 58 is significantly improved, the tightening margin of the seal member 58e between the cylinder 58a and the piston 58b is reduced, the hysteresis when the piston 58b moves is reduced, and the friction element 50 against the control hydraulic pressure is reduced. can be operated accurately.

Furthermore, since the actuator 58 can be provided apart from the center drive shaft 12, the piston 58b can be formed solid, and therefore, the sealing member 58e necessary for the actuator 58 is only the outer periphery of the piston 58b. The number of parts of the actuator 58 can be effectively reduced.

(Effects of the Invention) As explained above, in the transfer device for a four-wheel drive vehicle of the present invention, the friction element disposed between the output shaft and the distribution mechanism is arranged around the outside of the output shaft. a clutch plate disposed between the output shaft and the distribution mechanism; a sleeve axially movably fitted to the outside of the output shaft and capable of abutting against the clutch plate in the axial direction; a lever that is provided with a fulcrum that is rotatably supported by the transfer case, a force point that receives a pressing force at the other end, and a point of action that presses the sleeve in the axial direction at an intermediate portion; and a lever that applies a pressing force to the force point of the lever. Since the actuator is configured to include an actuator, when the pressing force of the actuator is applied to the force point of the lever, the L/bar exerts a lever action to increase the pressing force of the actuator and transmit it to the clutch plate. be able to.

Therefore, since the pressing force generated by the actuator itself can be reduced, the diameter of the actuator can be reduced, and since the actuator and the clutch plate are arranged independently, the clutch plate The diameter of the actuator is not restricted by the actuator (and can be determined by only the diameter necessary for the fastening force).

Therefore, the diameter of the clutch plate can be significantly reduced, and together with the reduction in the diameter of the actuator, the transfer device can be significantly reduced in size.

Furthermore, by reducing the diameter of the actuator, the seal length can be shortened, and the accuracy of the roundness of the actuator can be greatly increased, resulting in a significant improvement in sealing performance. can.

Furthermore, by improving the sealing performance in this way, it is possible to reduce the tightening margin of the sealing member (and reduce hysteresis), so the accuracy of friction element control can be significantly improved. It has a great effect.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a cross-sectional side view showing an embodiment of the present invention, FIG. 2 is a front view showing an embodiment of the sleeve used in the present invention,
FIGS. 3 and 4 are schematic configuration diagrams showing the operating states of the present invention, respectively. DESCRIPTION OF SYMBOLS 10... Transfer device, 12... Center drive shaft (output shaft), I4... Transfer case, 22... Main shaft, 26... Front drive shaft, 34... Molecule emF4.50.
...Friction element, 52...Clutch plate, 54...Sleeve, 56...Lever, 56b...First four part (fulcrum), 56c...Second recess (power point), 56d... Convex portion (point of action), 58...actuator. 2 people outside Figure 3

Claims (1)

[Claims] (1) An output shaft that outputs torque input from a power source to one of the front wheels or rear wheels, and a distribution mechanism that distributes the torque input to the output shaft to the other of the front wheels or rear wheels via a friction element. In a transfer device for a four-wheel drive vehicle, the friction element is arranged between a clutch plate that surrounds the outside of the output shaft and is arranged between the output shaft and the distribution mechanism, and a clutch plate that surrounds the outside of the output shaft and is disposed between the output shaft and the distribution mechanism; A sleeve fitted to be movable in the axial direction and capable of abutting against one side of the clutch plate in the axial direction, a fulcrum rotatably supported by the transfer case at one end, a force point receiving pressing force at the other end, and an intermediate portion. A transfer device for a four-wheel drive vehicle, comprising: levers each having a point of action that presses the sleeve in the axial direction; and an actuator that applies a pressing force to the point of force of the lever.