JPH0742994B2 - Viscous coupling - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a viscous coupling that transmits torque via a viscous fluid.

(Prior Art) Japanese Unexamined Patent Publication No. 62-286836 discloses a "drive device for a four-wheel drive vehicle". This is a device in which a differential limiting clutch (viscus coupling) and a switching clutch (multi-plate clutch) are arranged in series. In this device, torque is transmitted by a viscous coupling according to the rotation difference, and torque can be cut off by a multi-plate clutch. Therefore, if this is used in the power transmission system of a four-wheel drive (4WD) vehicle, the drive system is configured so that the drive force is sent to the non-slip side via the differential limiting clutch when a rotation difference occurs between the front and rear wheels. While you can
The front and rear wheels can be separated during braking to prevent the operation of the anti-skid brake system (ABS) from being hindered. Further, the torque transmission characteristics of the entire device can be changed by adjusting the fastening force of the multi-plate clutch. Furthermore, the multi-plate clutch can also act as a torque limiter.

(Problems to be solved by the invention) However, since the multi-plate clutch is separately added to give the viscous coupling a function of adjusting the torque transmission characteristics, the entire device is large and heavy, and the structure is large. It's complicated.

Therefore, an object of the present invention is to provide a small-sized and lightweight viscous coupling having a function of adjusting a torque transmission characteristic, having a simple structure.

[Structure of the Invention] (Means for Solving the Problems) A viscous coupling of the present invention includes first and second torque transmitting members arranged so as to be rotatable relative to each other, and the first and second torque transmitting members. And a first plate that is non-rotatably engaged with the first torque transmission member, and is arranged alternately with the first plate in the working chamber. A second plate loosely fitted to the second torque transmission member, a clutch plate non-rotatably engaged with the second torque transmission member and arranged between the second plates, and the clutch plate And a pressing means capable of pressing the clutch plate in the rotation axis direction and adjusting the pressing force so that the clutch plate and the second plate are frictionally fastened.

(Operation) When the clutch plate and the second plate are fastened by the frictional force by the pressing means, the non-rotational engagement between the second plate and the second torque transmission member is maintained. Here, when one of the transmission members rotates, this rotation is transmitted between the plates by the shear resistance of the viscous fluid, causing the other transmission member to rotate. If the rotation difference is large, the differential is greatly limited and a large torque is transmitted, and the differential with a small rotation difference is allowed, and the transmission torque becomes small. At this time, this torque transmission characteristic can be changed by adjusting the pressing force between the clutch plate and the second plate and changing the locking force between the second plate and the second torque transmission member. When the engagement between the clutch plate and the second plate is released, torque transmission between both torque transmission members can be cut off.

(Embodiment) An embodiment will be described with reference to FIGS. 1 to 3.

FIG. 3 shows the power system of a 4WD vehicle using this embodiment. Hereinafter, the left and right directions are the left and right directions in FIG. 1, and the left and right directions correspond to the front of the vehicle (upper side in FIG. 3). In addition,
Members and the like without numbers are not shown.

First, the structure of the power system of this vehicle will be described with reference to FIG. This power system includes an engine 1, a transmission 3, a front differential 5 (a front wheel differential device), left and right front wheels 7 and 9, a transfer 11, a viscous coupling 13, a propeller shaft 15, a rear differential 17 (rear wheel). Side differential device), left and right rear wheels
It is composed of 19,21 and so on.

Next, the structure of the viscous coupling 13 will be described with reference to FIG. The housing 23 (first transmission member) and the hub 25 (second transmission member) are arranged so as to be rotatable relative to each other. Hub
25 is spline-fitted to the transmission shaft 27, and a bearing 29 is arranged between the housing 23 and the transmission shaft 27. To fix the bearing 29 in the axial direction, a washer 31 and a lock nut 33 are attached to the transmission shaft 27, and a retaining ring 35 is attached to the housing 23. Housing 23 has bolt holes
A flange is connected to the transfer 11 side by a bolt screwed to 37, and the transmission shaft 27 is connected to the propeller shaft 15 side.

A pressing member 39 is axially movably arranged between the inner circumference of the housing 23 and the outer circumference of the transmission shaft 27, and a bearing 41 and a seal 43 are arranged between the member 39 and the housing 23. ing. The pressing member 39 is spline-fitted to the hub 25 in the housing 23 to prevent rotation.

The working chamber 4 is provided between the housing 23, the hub 225 and the pressing member 39.
5, the working chamber 45 is filled with high-viscosity silicone oil (viscous fluid). Housing 23 and hub
X-rings 47 and 49 (seal having an X-shaped cross section) are arranged between the 25 and the member 39, and an O-ring 51 is arranged between the hub 25 and the member 39, and the working chamber 45 is closed. Keep it tight.

As shown in an enlarged view in FIG. 1B, plates 53 and 55 are alternately arranged in the working chamber 45. The outer plate 53 (first plate) is spline-connected to the inner circumference of the housing 23 so as to be movable in the axial direction, and a clutch plate is provided on the inner edge side of the inner plate 55 (second plate) loosely fitted to the hub 25. Certain rings 57 are arranged alternately with the plates 55, and the rings 57 are spline-connected to the outer periphery of the hub 25 so as to be axially movable. A pressure receiving ring 59 is attached to the hub 25 on the left side of the left end ring 57, and
The right side of 57 faces the left end of the pressing member 39. plate
55 and the ring 57 are pressed by the pressing member 39 between the pressure receiving ring 59 and fastened. Thus, the clutch 61 that connects the plate 55 loosely fitted to the hub and the hub 25 is configured.

On the right side of the housing 23, a ring-shaped cylinder member 63 fixed to the vehicle body side is arranged coaxially with the transmission shaft 27. A bearing 65 is arranged between the cylinder member 63 and the transmission shaft 27. A piston 67 is fitted in the cylinder member 63 so as to be slidable in the axial direction. The sliding parts of the cylinder member 63 and the piston 67 are kept liquid-tight by O-rings 69 and 71. Thus, the hydraulic actuator 73 (pressing means) is configured. Hydraulic pressure is supplied to the actuator 73 from a hydraulic source via a control valve device and a hydraulic port 75. Piston 67
Is connected to the pressing member 39 via a bearing 77.
The actuator 73 engages the clutch 61 via these. The actuator 73 is automatically operated according to the steering condition and the road surface condition, and is configured to stop differentially during braking.

In this way, the viscous coupling 13 is constituted.
Next, the function of the viscous coupling 13 will be described.

When hydraulic pressure is supplied to the actuator 73, the clutch 61 is engaged, and the plate 55 has a strength corresponding to the strength of this engaging force.
Is connected to the hub 25. The rotation of the housing 23 due to the driving force from the engine 1 is transmitted from the plate 53 to the plate 55 by the shear resistance of the silicone oil, and the hub 25 is rotated. At this time, if the rotation difference between the plates 53 and 55 is large, the differential limiting force becomes strong and a large torque is transmitted. If this rotation difference is small, the differential is allowed and the transmission torque becomes small.

If the fastening force of the clutch 61 is sufficiently increased to eliminate slippage, the rotation difference between the housing 23 and the hub 25 and the rotation difference between the plates 53 and 55 become equal, and the torque transmission characteristic at this time is shown in the graph of FIG. It looks like 79. The rotation difference (ΔN) in FIG. 2 is the rotation difference between the housing 23 and the hub 25. If the fastening force of the clutch 61 is weakened, the difference in rotation between the plates 53 and 55 becomes smaller due to the slip between the plate 55 and the ring 57, and the transmission torque becomes smaller, resulting in the characteristic shown in the graph 81. If the slip is increased, the transmission torque is further reduced as shown in graph 83. Further, when the clutch 61 is opened, the transmission torque becomes only a slight torque from the plate 55 to the ring 57 due to the shear resistance of the silicon oil, and the housing 23 and the hub 25 are substantially separated from each other and the torque transmission is interrupted.

In this way, the viscous coupling 13 can adjust the torque transmission characteristic and can substantially cut off the torque transmission. Clutch when excessive torque is input
61 slips and acts as a torque limiter. Also, the clutch 61
Unlike the conventional example, the structure is simple, and the size and weight are small because it is integrated.

Next, the function of the viscous coupling 13 will be described according to the power performance of the vehicle shown in FIG.

The rotation of the engine 1 is shifted by the transmission 3 and is output from the front differential 5 to the left and right front wheels 7 and 9 separately.

When the clutch 61 is engaged, the driving force is
11, output from the viscous coupling 13, propeller shaft 15 via the rear differential 17 to the left and right rear wheels 19, 21 separately.
The vehicle enters the 4WD state.

In the 4WD state, when the difference in rotation between the front and rear wheels is small, such as when driving on a good road, the rear wheel is affected by the characteristics of the viscous coupling 13.
Almost no driving force is transmitted to the 19,21 side. Therefore,
The vehicle is essentially in front-wheel-drive 2WD state, which significantly improves fuel efficiency.

When the front wheels 7 and 9 run idle on a bad road or the like and a difference in rotation occurs between the front and rear wheels, the driving force is transmitted to the rear wheels 19 and 21 via the viscous coupling 13, and high running performance is obtained. Further, since a small rotation difference generated between the front and rear wheels during turning is absorbed by the viscous coupling 13, a smooth turning can be performed. Garage and U
Even when the vehicle makes a sharp turn such as a turn, the difference in rotation between the front and rear wheels is absorbed by the viscous coupling 13, so that the tight corner braking phenomenon is prevented.

When the clutch 61 is released, the transmission of the driving force to the rear wheels is substantially cut off regardless of the rotation difference, the rear wheels are in the disengaged state, and the vehicle is in the 2WD state. This separation is automatically performed during braking, and the interference of braking force between the front and rear wheels (for example,
The lock of the front wheel affects the rear wheel) and the normal function of ABS is protected.

Note that the clutch 61 has an outer plate 53 and a housing 23.
It may be provided between the two or both.

The clutch 61 may be divided into left and right, and the left and right actuators may be separately engaged. In this case, the action of fastening only one side can be expected.

FIG. 4 relates to another embodiment, in which the actuator 73 is composed of an electromagnetic clutch. In this way, the friction generation part of the electromagnetic clutch is
Since it is installed on the 23 side, it is compact and has improved in-vehicle performance.

EFFECTS OF THE INVENTION Since the viscous coupling of the present invention has the friction clutch provided between the plate and the transmission member, the torque transmission characteristics can be adjusted, and the structure is simple, and the size and weight are small.

[Brief description of drawings]

FIG. 1 (a) is a sectional view of one embodiment, and FIG. 1 (b) is (a).
FIG. 2 is an enlarged view of a main part of FIG. 2, FIG. 2 is a graph showing characteristics of this embodiment, FIG. 3 is a skeleton mechanism diagram showing a power system of a vehicle using this embodiment, and FIG. 4 is a cross section according to another embodiment. It is a figure. 23 …… Housing (first transmission member) 25 …… Hub (second transmission member) 45 …… Working chamber 53 …… Plate (first plate) 55 …… Plate (second plate) 61 …… Clutch 73 ...... Actuator

Claims (1)

[Claims] 1. A first and a second torque transmitting member arranged so as to be rotatable relative to each other, a working chamber provided between the first and the second torque transmitting member and having a viscous fluid sealed therein, A first plate non-rotatably engaged with the first torque transmission member, and a second plate alternately arranged with the first plate in the working chamber and loosely fitted to the second torque transmission member.
A plate, a clutch plate non-rotatably engaged with the second torque transmission member and disposed between the second plates, and a frictional force between the clutch plate and the second plate. A viscous coupling, further comprising: a pressing unit that presses the clutch plate in the rotational axis direction and can adjust the pressing force.