JPH02134422A - Power transmission - Google Patents

Abstract

PURPOSE:To make transfer torque larger during low-speed running by installing a centrifugal clutch interposingly between both first and second rotating members in an operating chamber sealed with a viscous fluid, and when the absolute rotational speed is low, restricting relative rotation between these rotating members, but when it is high speed, making the relative rotation so as to be restricted the other way. CONSTITUTION:When a vehicle runs at high speed (absolute rotational speed is high), a first rotating member 12 and a second rotating member 13 rotate at high speed at the same time. Therefore a clutch member 20 of a centrifugal clutch 18 turns round to the outer circumferential side against the energizing force of a spring by dint of centrifugal force, and thereby the centrifugal clutch 18 is separated. When a front wheel is slipped while the vehicle runs on a rough road at low speed, there is produced a speed difference between these rotating members 12 and 13, and a viscous fluid is cut off by resisting plates 15 and 16, whereby shearing force is transmitted to the rear wheel as torque. In addition, the clutch member 20 comes into frictionally contact with the rotating member 12 by dint of the spring 21, therefore both rotating members 12 and 13 are not allowed of the speed difference, so that torque of the rotating member 12 is transmitted to the rear wheel from the rotating member 13. Consequently, it can get out of slipping state.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a power transmission device that is incorporated into a power transmission system of a vehicle or the like and utilizes viscous fluid.

(Prior Art) As a conventional power transmission device, for example, there is a viscous coupling interposed between a transfer and a propeller shaft of a front engine, front drive (FF) based four-wheel drive vehicle. This viscous coupling includes a first rotating member connected to the drive shaft of the transfer, a second rotating member connected to the propeller shaft, and the first rotating member connected to the propeller shaft.
It consists of a working chamber defined by a rotating member and filled with viscous fluid. The working chamber includes a first resistance plate and a second resistance plate.
A resistance plate is housed, and the first and second low resistance plates at the mouth are the first and second resistance plates, respectively.
．． It is attached to two rotating members.

The front wheels are on the road! When a vehicle slips on a rough road with a low coefficient of friction, a large difference in rotational speed occurs between the front and rear wheels.

Therefore, the first resistance plate and the second resistance plate rotate relative to each other to shear the viscous fluid. The photopic force of the viscous fluid at this time is transmitted as torque to the rear wheels, which push the vehicle out of the slip state.

On the other hand, when turning the steering wheel sharply at low speeds, such as when parking the vehicle, there will be a difference in rotational speed between the front wheel drive shaft and rear wheel drive shaft, as well as between the left and right wheels, but this difference in rotational speed is small. Absorbed through this viscous coupling,
This prevents the so-called tight corner braking phenomenon from occurring.

(Problem to be Solved by the Invention) However, in such a conventional power transmission device, the number of rotations generated between the front wheel drive shaft and the rear wheel drive shaft during low speed and large steering such as during 11 storage, etc. Although it can be absorbed,
When a front wheel or a rear wheel gets stuck while driving at low speed on a rough road, there is a problem in that the vehicle cannot quickly escape from the stuck state because the torque transmitted between the first rotating member and the second rotating member is small.

Therefore, in order to quickly escape from the stack, the relative rotation between the first rotating member and the second rotating member may be further limited by other limiting means. However, there is an anti-lock braking system (A, B S) on the rear wheel side.
If the front wheels lock when the brakes are applied, the front wheel drive shaft and rear wheel drive shaft will be directly connected by further restricting the relative rotation, causing the rear wheels to lock as well. There was a problem that the B S j did not operate properly.

[Structure of the invention] (Means for solving one problem) In order to solve such a problem, the present invention includes a first rotating member and a second rotating member that are arranged to be relatively rotatable. , a working chamber defined by the first rotating member and the second rotating member and filled with a viscous fluid, the viscous fluid being sheared by the relative rotation between the first rotating member and the second rotating member. In a power transmission device that transmits torque between a first rotating member and a second rotating member, a centrifugal clutch is interposed between the first rotating member and the second rotating member,
This centrifugal clutch is configured to limit the relative rotation only when the absolute rotational speed is low, and not to limit the relative rotation when the absolute rotational speed is high.

When the first rotating member and the second rotating member rotate relative to each other, the viscous fluid is sheared and torque is transmitted between the first rotating member and the second rotating member. When the absolute rotational speed is low, the centrifugal clutch also limits the relative rotation between the first and second rotating members, so that torque transmission between the first and second rotating members is improved.

Further, when the absolute rotational speed is high, the relative rotation is not limited by the centrifugal clutch, so the relative rotation between the first rotating member and the second rotating member is allowed.

(actual example) The present invention will be explained below based on the drawings.

1 to 4 are diagrams showing an embodiment of a power transmission device according to the present invention. This embodiment is an example in which the center differential is interposed between the front wheel drive shaft and the rear wheel drive shaft of an FF-based four-wheel drive vehicle.

First, the configuration will be explained.

In FIG. 1, the torque of a horizontally placed engine 1 is shifted by a transmission 2 and transmitted to a transfer 3. As shown in FIG. Transf? 3 transmits the transmitted torque to a front differential 4 housed therein, and transmits the torque to a rear differential 9 via a power transmission device [5 and a propeller shaft 6]. The transmitted torque is transmitted to the front axle 7 by the front differential 4.
a, 7b to the left and right front wheels 8a, 8b, and a rear differential 9 differentially distributes the power to the left and right rear wheels 11a, 11b via the rear axles 10a, 10b.

Here, the power transmission device fff5 will be explained with reference to FIG. 2.

Reference numeral 12 designates a case-shaped first rotating member to which engine torque is transmitted via the transmission 2 and transfer 3, and which is connected to the drive shaft 3a of the transfer 3. A ring-shaped second rotating member 13 is inserted through the first rotating member 12 and is arranged to be relatively rotatable, and the second rotating member 13 is connected to the propeller shaft 6 . A working chamber 14 is defined by the first rotating member 12 and the second rotating member 13, and the working chamber 14 is filled with silicone oil as a viscous fluid. A plate-shaped first resistance plate 15 and a second rotating member 13
A substantially disc-shaped second resistance plate 16 attached to is housed therein. Further, an interlocking member 17 having a U-shaped cross section as a whole and having a shape that covers the first rotating member 12 is fixed to the second rotating member 13 on the right side of the working chamber 14 in FIG.

Therefore, the interlocking member 17 can also be considered as the second rotating member 13.

A centrifugal clutch 18 is interposed between the interlocking member 17 and the first rotating member 12, as shown in FIG. That is, the clutch member 2 is connected to the interlocking member 17 through one bottle.
0 is attached, and this clutch member 20 can swing around the bin 19. The clutch member 20 is provided with a friction surface 20a that can make frictional contact with the outer circumferential surface 12a of the first rotating member 12, and the biasing force of a spring 21 interposed between the clutch member 20 and the interlocking member 17 causes S
The rubbing surface 20a makes frictional contact with the outer circumferential surface 12a of the first rotating member 12.

Next, the effect will be explained. When the vehicle travels at high speed on a paved road (when the absolute rotational speed is high), the torque of the engine 1 is transferred from the transmission 2 to the front wheel drive shafts 7a, 7.
However, since the power transmission device 5 is provided between the transfer 3 and the propeller shaft 6, almost no torque is transmitted to the propeller shaft 6, causing the rear wheels to spin around. It runs as a front-wheel drive vehicle. That is, the first rotating member 12 and the second rotating member 1
3 and rotate at high speed almost simultaneously. Therefore, the clutch member 20 of the centrifugal clutch 18 rotates toward the outer circumference about the bottle 19 by this centrifugal force against the biasing force of the spring 21, and the friction surface 20a is separated from the outer circumferential surface of the first rotating member. Then, the centrifugal clutch 18 is disengaged. Therefore, the front wheel drive shaft 7a.

7b and the rear wheel drive shafts 10a, 10b are not firmly connected, and even if there is a rotation speed difference between the front wheels 8a, 8b and the rear wheels 11a, 11b, this power transmission device 5 can absorb it. As a result, if the invading side is equipped with an anti-lock braking system (ABS), the front wheel 8a will be damaged when the brakes are applied.

Even if 8b locks, the front wheel drive shafts 7a, 7b and the rear wheel drive shafts 10a, 10b are not firmly connected, so even the rear wheels 11.11b will not be locked.
BS operates properly.

Next, when the vehicle travels at low speed on a rough road with a small coefficient of road friction (when the absolute rotational speed is low), the front wheels 8a, 8
b slips, the front wheel drive shaft 7a.

The first rotating member 12 connected to the engine 7b is directly driven by the engine 1, but since the resistance of the front wheels is low, only a small amount of torque is transmitted to the front wheels.

Here, since the rear wheels 11a and 11b are rotating less than the rotational speed of the engine (front wheel drive shafts 7a and 7b), the rear wheel drive shafts 1oa.

The second rotating member 13 connected to the first rotating member 12
Rotate less. For this reason, front wheel drive 'N17a,
7b and the rear wheel drive shafts 10a, 10b, that is, the first
A difference in rotational speed occurs between the rotating member 12 and the second rotating member 13. Therefore, the first resistance plate 15 and the second resistance plate 16
The viscous fluid is sheared by this, and the shearing force at this time is applied as torque from the rear wheel drive shafts 10a, 10b to the rear wheels 11a,
11b.

Here, since the rotational speed of the second rotating member 13 is low, the biasing force of the spring 21 is greater than the centrifugal force of the clutch member 20 of the centrifugal clutch 18. Therefore, the clutch member 20 is moved by the biasing force of the spring 21.
The friction surface 20a makes frictional contact with the outer circumferential surface 12a of the first rotating member 12, and the first rotating member 12 and the second rotating member 13 are connected by the centrifugal clutch 18 without allowing much difference in rotational speed. Therefore, the torque transmitted to the first rotating member 12 is transmitted from the second rotating member 13 to the rear wheel 11a.

11b.

Therefore, as shown in FIG. 4, if the absolute rotational speed of the second rotating member 13 close to the vehicle speed is N, and the torque transmitted between the first rotating member 12 and the second rotating member 13 is expressed as a king, then the absolute rotational speed N When the absolute rotational speed N is high (during high-speed driving), the torque under is low, as shown by the solid line, but when the absolute rotational speed N is low (during low-speed driving), the torque peak is high. Note that the two-dot chain line indicates the torque under when only the centrifugal clutch 18 is operated, and the broken line indicates the torque T when only the actuation type 14 is operated.

As a result, the rear wheels 11a, 11t) push out the vehicle, causing the front wheels 8a, 8b to quickly escape from the slipping state.

On the other hand, when parking the vehicle, etc., the front wheel drive shaft 7a.

A difference in rotational speed occurs between the rear wheel drive shafts 7b and the rear wheel drive shafts 10a and 10b. At this time, the centrifugal clutch 18
2 and the second rotating member 13 are connected to be relatively rotatable, but not directly connected. Therefore, this power transmission device absorbs the difference in rotational speed between the first rotating member 12 and the second rotating member 13, and prevents the tight corner braking phenomenon from occurring.

[Effects of the Invention] As explained above, according to the present invention, a centrifugal clutch is interposed between the first rotating member and the second rotating member, and the centrifugal clutch is activated only when the absolute rotational speed is low. Since the relative rotation is limited and the relative rotation is not limited when the absolute rotational speed is high, the torque transferability between the first rotating member and the second rotating member is improved. Therefore, when this power transmission device is installed in the power transmission path of a four-wheel drive vehicle, a large torque can be quickly transmitted to the wheel with a higher coefficient of friction. That is, the responsiveness of torque transmission to wheels with a high friction coefficient and the transmitted torque m can be improved. As a result, the vehicle can be quickly released from a slipping state. Furthermore, if the vehicle is equipped with an anti-lock braking system (ABS), even if the front wheels lock, the rear wheels will not lock either, and the ABS will operate properly.

[Brief explanation of the drawing]

1 to 4 are diagrams showing one embodiment of a power transmission device according to the present invention, and FIG. 1 is a schematic overall view of a four-wheel drive vehicle in which this power transmission device is provided as a center differential;
Fig. 2 is a schematic sectional view of this power transmission device, Fig. 3 is a side view of the centrifugal clutch, and Fig. 4 is a schematic sectional view of this power transmission device.
．． It is a graph showing the transmission torque T between two rotating members. 5... Power transmission device 12... First rotating member 13... Second rotating member 1
4... Actuation type 18... Centrifugal clutch 5.
...Power transmission device 12...First rotating member 13...Second rotating member 14... Actuation type agent Yasuo Miyoshi, patent attorney Figure 1

Claims (1)

[Claims] It includes a first rotating member and a second rotating member that are arranged to be relatively rotatable, and a working chamber defined by the first rotating member and the second rotating member and containing a viscous fluid. In a power transmission device that transmits torque between the first rotating member and the second rotating member when sheared by relative rotation between the first rotating member and the second rotating member, the first rotating member and the second rotating member A centrifugal clutch is interposed between the member and the
A power transmission device characterized in that the centrifugal clutch limits the relative rotation only when the absolute rotation speed is low, and does not limit the relative rotation when the absolute rotation speed is high.