JP2000230585A - Power transmission device - Google Patents

Abstract

(57) [Problem] To provide a viscolock-type power transmission device capable of suppressing the upper limit of transmission of driving force when a vehicle rotates at a high differential speed. SOLUTION: In a viscolock type power transmission device B, when first and second rotating members 1 and 2 rotate at a predetermined speed or more, a relief valve 23 opposes the urging force of an urging spring 25. It is configured such that it is separated from the valve seat 22 by being displaced radially outward, and the relief flow path 19 is opened.
Further, a pressure regulating valve 30 is provided between the reservoir 16 and the pressure chamber 12, and the first and second rotating members 1 and 2 are provided.
2 rotates at a speed equal to or higher than the predetermined speed, the adjustment valve body 33 is displaced radially outward against the urging force of the urging spring 35 so that the flow path 28 directly communicating with the reservoir 16 is shut off. It is configured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a power transmission device for transmitting a driving torque between rotating members relatively rotatable about the same axis.

[0002]

2. Description of the Related Art Conventionally, various drive types for driving front and rear wheels of a four-wheel drive vehicle have been developed. Among them, a viscous coupling is provided in the middle of a propeller shaft for transmitting drive torque to a rear wheel or a front wheel. And a drive torque is transmitted to a rear wheel or a front wheel when a rotational speed difference occurs between the front and rear wheels. According to this drive type, not only can a drive torque be transmitted to the rear wheels or the front wheels as soon as a rotational speed difference occurs between the front and rear wheels, but also the occurrence of tight corner braking can be prevented. It has various excellent characteristics, such as being able to prevent rotational interference between wheels.

However, the viscous coupling transmits a driving torque by using a viscous resistance generated between thin plates that rotate relatively in a high-viscosity fluid, so that the driving torque that can be transmitted is naturally limited. It is not suitable for transmitting large torque.

Accordingly, a friction clutch interposed between the first and second rotatable members which can rotate relative to each other, and a pressure clutch defined between the first and second rotatable members and filled with a highly viscous fluid. A rotating body that rotates relative to the second rotating member by integrally rotating with the first rotating member in the pressure chamber, and between the rotating body and the second rotating member. There has been proposed a power transmission device called a so-called viscolock, which includes a piston pressing means for pressing a piston by the pressure of the high-viscosity fluid and causing the friction clutch to come into close contact, and capable of transmitting a large torque.

In a vehicle equipped with the above-described power transmission device in the middle of a propeller shaft, the relative rotational speed between the first and second rotating members is large regardless of the speed of the vehicle. Thus, the magnitude of the driving force transmitted to the rear wheels or the front wheels is determined.

[0006] On the other hand, when the vehicle is running at high speed, by driving only the front wheels or only the rear wheels, it is possible to reduce the driving resistance due to the circulation of the driving torque between the front and rear wheels, and to improve fuel efficiency. However, the viscolock-type power transmission device described above has a function of interrupting the transmission of the driving force when the running speed of the vehicle becomes higher than a predetermined value, and enabling only the front wheels or only the rear wheels to be driven. I haven't. Japanese Patent Laid-Open Publication No. Hei 10-238564 discloses a viscolock-type power transmission device that can cut off transmission of driving force when the vehicle runs at high speed.
FIG. 4 shows a partial cross-sectional view of the power transmission device 100.

[0007] As shown in FIG.
0 denotes first and second rotating members 51 and 52 which can be relatively rotated around the same axis, and these first and second rotating members 51 and 52
A pressure chamber 62 defined between the first and second rotating members 51 and 52 and filled with a high-viscosity fluid, for example, silicon oil;
A rotating body 64 rotatable relative to the second rotating member 52 by integrally rotating with the first rotating member 51 in the pressure chamber 62; and the rotating body 64 and the second rotating member 52 And a piston pressing means 60 for pressing the piston 61 by the pressure of the silicon oil generated between the piston and the friction clutch 53, and a reservoir 66 communicating with the pressure chamber 62 via a flow path.

Further, in the power transmission device 100, a relief valve 70 provided in a relief channel 69 communicating the reservoir 66 and the pressure chamber 62 has a relief valve body 73 which can be displaced in the radial direction with respect to the rotation axis. And a biasing spring 75 for biasing the relief valve body 73 in the radial direction so as to be seated on the valve seat 72. Therefore, when the first and second rotating members 51 and 52 rotate at a predetermined speed or more, the relief valve body 73 separates from the valve seat 72 due to the centrifugal force against the urging force of the urging spring 75, and the relief flow flows. The road 69 is opened.
Further, a relief channel 69 due to an increase in the pressure in the pressure chamber 62.
The release valve element 73 is also affected by the silicon oil inside.
Can open the escape channel 69. Due to this opening operation, the pressure in the pressure chamber 62 cannot rise, and the transmission of the driving force remains interrupted because the piston 61 does not press the friction clutch 53.

[0009]

However, the power transmission device 1 disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 10-238564.
Even when the vehicle is running at a high differential speed, such as at the time of sudden start, braking, escape on a low-mu road (ice-burn, snowy road, etc.), escape from a wheel, etc., transmission of driving force is performed. The upper limit could not be suppressed. As described above, if the upper limit of the driving force cannot be suppressed, there is a possibility that the power transmission device, which has recently been increased in size and weight, may be damaged.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a viscolock-type power transmission device capable of suppressing an upper limit of transmission of driving force when a vehicle rotates at a high differential speed.

[0011]

SUMMARY OF THE INVENTION It is an object of the present invention to provide first and second rotating members which are relatively rotatable about the same axis, and a friction member interposed between the first and second rotating members. A clutch, a pressure chamber defined between the first and second rotating members and filled with a high-viscosity fluid, and the second rotating member being integrally rotated with the first rotating member in the pressure chamber. A rotating body that is rotatable relative to the rotating member, and a piston pressing unit that presses a piston by the pressure of the high-viscosity fluid generated between the rotating body and the second rotating member, thereby bringing the friction clutch into close contact. And a reservoir communicating with the pressure chamber via a flow path, a relief valve provided in a relief flow path communicating the reservoir with the pressure chamber, a relief capable of being displaced in a radial direction with respect to the axis. Valve and the relief valve A biasing spring for biasing radially inward to seat on the valve seat, wherein when the first and second rotating members rotate at a predetermined speed or more, the relief valve body is biased by the biasing spring. In a power transmission device that separates from the valve seat by being displaced radially outward against the urging force of a spring and opens the relief passage, a pressure regulating valve is provided between the reservoir and the pressure chamber. The pressure adjusting valve has an adjusting valve body that can be displaced in the radial direction with respect to the axis, and an urging spring that urges the adjusting valve body inward in the radial direction. When the first and second rotating members rotate at a speed equal to or higher than the predetermined speed, the adjusting valve body is displaced radially outward against the urging force of the urging spring, thereby directly communicating with the reservoir. By providing a power transmission device characterized by shutting off the It is.

According to the above configuration of the present invention, the first and the second
When the transmission member rotates at a speed equal to or higher than a predetermined speed and the pressure in the pressure chamber rises, the relief valve body constituting the relief valve opens the relief flow path, and the regulating valve body constituting the pressure regulating valve is directly connected to the reservoir. Block the communicating flow path. Therefore, not only the pressure is released by the relief valve, but also the supply of the high-viscosity fluid from the reservoir is shut off by the pressure regulating valve, and the pressure rise in the pressure chamber can be suppressed reliably, so that the vehicle can rotate at high differential rotation. In this case, the upper limit of the transmission of the driving force can be suppressed. As a result, even if the power transmission device is reduced in size and weight and the parts are shared for different vehicle types due to the reduction in size and weight, there is no problem in durability performance, so that the drive system can be protected.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a cross-sectional view of a viscolock-type power transmission device B according to an embodiment of the present invention, and FIG. 2 is a partially enlarged cross-sectional view illustrating a state in which a pressure adjusting valve 30 of the power transmission device B is operated. . However, FIG.
In FIG. 2, the tube 27 is shown in an expanded state for explanation.

As shown in FIG. 1, a power transmission device B includes a hub 1 as a first rotating member which is driven to rotate around a rotation axis C by a drive shaft (not shown), and the rotation axis with respect to the hub 1. And a housing 2 that is a second rotating member that is relatively rotatable around C. The housing 2
Is connected to the driven member 6. Further, between the hub 1 and the housing 2, a multi-plate clutch 3 as a friction clutch and a piston 1
1 is interposed.

The multi-plate clutch 3 includes a plurality of inner plates 4 which are engaged with the hub 1 in the rotation direction, and a plurality of inner plates 4 which are alternately arranged with the inner plates 4 and are engaged with the housing 2 in the rotation direction. And an outer plate 5. The inner plate 4 and the outer plate 5 are configured to be pressed by the piston 11 to be in close contact with each other and to transmit a driving torque between the hub 1 and the housing 2.

The piston 11 can be displaced in a direction of a rotation axis C fitted inside the housing 2 and forms a pressure chamber 12 together with the housing 2. The pressure chamber 12 is sealed with silicone oil as a highly viscous fluid. In the pressure chamber 12, an annular pump disk 13 coaxially rotatable with respect to the housing 2 within a predetermined angular range and the hub 1 are engaged with the hub 1 by splines to rotate integrally. An annular feed disk 14 as a rotating body is disposed.

On the other hand, the multi-plate clutch 3 of the housing 2
A compensating piston 18, which is constantly urged by a wave spring 17, is slidably fitted in the direction of the rotation axis C in a reservoir 16 that stores silicon oil formed at the end opposite to the above. The reservoir 16 and the pressure chamber 12 communicate with each other via flow paths 26 and 28, and the pressure chamber 1
2 compensates for the increase or decrease of the silicone oil.

A relief valve 19 (a cross section is shown in the lower half of FIG. 1) is provided in a relief channel 19 that connects the reservoir 16 and the pressure chamber 12. This relief valve 2
Numeral 0 has a relief valve element 23 that can be displaced in the radial direction with respect to the rotation axis C, and an urging spring 25 that urges the relief valve element 23 in the radial direction to be seated on the valve seat 22. Further, in addition to the valve element 23, a pressure regulating valve 30 (a cross section is shown in the upper half in the figure) between the reservoir 16 and the pressure chamber 12.
Is provided. The pressure control valve 30 includes a control valve body 33 that can be displaced in the radial direction with respect to the rotation axis,
An urging spring 3 for urging the adjusting valve body 33 inward in the radial direction.
Five.

Next, the operation of the power transmission device B of the present invention will be described. When the hub 1 and the housing 2 of the power transmission device B rotate at a speed higher than a predetermined speed and the pressure in the pressure chamber 12 increases, the relief valve body 23 separates from the valve seat 22 against the urging force of the urging spring 25. Then, the escape channel 19 is opened.
Due to this opening operation, the pressure inside the pressure chamber 12 cannot rise, and the transmission of the driving force can be cut off because the piston 11 does not press the friction clutch 3.

When the silicon oil flows from the pipe 27 communicating with the pressure chamber 12 due to a rise in the pressure in the pressure chamber 12, the adjusting valve body 33 is also displaced radially outward against the urging force of the urging spring 35. . Then, as shown in FIG. 2, the flow path 28 directly communicating with the reservoir 16 is shut off. By this shutoff operation, the silicon oil in the reservoir 16 is not supplied to the pressure chamber 12, so that the piston 11 does not press the friction clutch 3 and the upper limit of the transmission of the driving force can be suppressed.

FIG. 3 shows a case where there is no relief valve and no pressure regulating valve, and a case where there is only a relief valve, that is, in the case of the power transmission device described in Japanese Patent Application Laid-Open No. 10-238564, the relief valve and the pressure regulating 5 is a graph showing the relationship between the rotational speed S, the pressure P, and the torque T in a case where both valves are provided, that is, in each case of the present invention.

As shown in FIG. 3, when both the relief valve and the pressure regulating valve are not provided, as the rotational speed S increases, the linear function is directly expressed as P = kS (k is a constant). As described above, the pressure P and the torque T increase. On the other hand, when there is a relief valve, up to the rotation speed S1, the linear function is represented by P = kS. However, when a predetermined pressure is reached at the rotation speed S1, the pressure is released by the relief valve body. Therefore, it can be seen that the slope k becomes a slightly smaller constant and the torque can be suppressed to some extent. In the case of the present invention, that is, in the case of the present invention, not only the pressure is released by the relief valve, but also there is an adjusting valve which shuts off the supply from the reservoir. It can be seen that the pressure can be made substantially constant, and the pressure rise rate can be suppressed to almost zero.

The embodiment of the present invention has been described above.
The present invention is not limited to the above-described embodiment, and can be appropriately changed and improved based on the gist of the present invention.
For example, in the above-described embodiment, the case where the drive torque is transmitted from the hub 1 to the housing 2 has been described. However, the drive torque may be transmitted from the housing 2 to the hub 1.

[0024]

As described above, the power transmission device of the present invention is provided with not only the relief valve for releasing the pressure but also the pressure regulating valve for shutting off the supply from the reservoir. The upper limit of the transmission of the driving force when rotating can be suppressed. Therefore, even if the power transmission device is reduced in size and weight and the components for different types of vehicles are shared by the reduction in size and weight, no problem occurs in the durability performance, so that the drive system can be protected. Further, since the pressure regulating valve does not require a complicated structure such as one controlled by a sensor using electric means, the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a power transmission device according to an embodiment of the present invention.

FIG. 2 shows a state in which the pressure regulating valve of FIG. 1 is operated.

FIG. 3 shows the rotational speed S, the pressure P and the torque T in the case where there is no relief valve and the pressure regulating valve, in the case where there is only the relief valve, and in the case where both the relief valve and the pressure regulating valve are present. 6 is a graph showing the relationship of.

FIG. 4 is a partial sectional view of a conventional power transmission device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hub 2 Housing 3 Multi-plate clutch 11 Piston 12 Pressure chamber 14 Feed disk 16 Reservoir 19 Relief flow path 20 Relief valve 23 Relief valve element 25 Urging spring 30 Pressure regulating valve 33 Adjusting valve element 35 Urging spring

Continued on front page F-term (reference)

Claims (1)

[Claims] A first and a second rotating member rotatable relative to the same axis, a friction clutch interposed between the first and the second rotating members, and a first and a second rotating members. A pressure chamber defined between members and filled with a high-viscosity fluid;
A rotating body that is rotatable relative to the second rotating member by rotating integrally with the first rotating member in the pressure chamber, and is generated between the rotating body and the second rotating member. Pressing the piston by the pressure of the highly viscous fluid,
A piston pressing means for bringing the friction clutch into close contact with each other, a reservoir communicating with the pressure chamber via a flow path, a relief valve provided in a relief flow path communicating the reservoir with the pressure chamber, the relief valve is provided on the axis. A relief valve that can be displaced in the radial direction, and a biasing spring that biases the relief valve body inward in the radial direction to seat on the valve seat; and the first and second rotations. When the member rotates at a speed higher than a predetermined speed, the release valve is displaced radially outward against the biasing force of the biasing spring, thereby separating from the valve seat and opening the release flow path. In the transmission device, a pressure regulating valve is provided between the reservoir and the pressure chamber, and the pressure regulating valve is displaceable in a radial direction with respect to the axis; And a biasing spring that biases the inward in the radial direction. When the first and second rotating members rotate at a speed equal to or greater than the predetermined speed, the regulating valve body is displaced radially outward against the urging force of the urging spring, so that the reservoir is displaced. A power transmission device characterized in that a flow path directly communicating with the power transmission device is blocked.