JP2001050303A - Coupling and differential device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve on-vehicle property by preventing loss of driving force, decrease of fuel efficiency, heat generation, and wear, improving durability, reducing loss of magnetic force, and attaining compactness. SOLUTION: This device is provided with torque transmission members 7, 9, a main clutch 13 placed therebetween, a pilot clutch 21, a cam 17 placed in series with the clutch 21 between the torque transmission member 7 and a static side member 39 so as to be operated to connect the clutch 13 by receiving transmission torque between the members 7, 9 when the clutch 21 is connected, an energizing member 27, and an electromagnet 31. In this case, the energizing member 27 presses the clutch 21, and the electromagnet 31 cancels pressing force of the energizing member 27 through an armature 29, a connecting part 53, and a pressing member 25 to release connection of the clutch 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coupling, which is connected by an urging member and is disconnected by an electromagnet, and a clutch for limiting a differential, which is connected by an urging member and is disconnected by the electromagnet. It relates to a differential device.

[0002]

2. Description of the Related Art A conventional structure is disclosed in Japanese Patent Publication No. 2844.
No. 006 (patent number), a power transmission device 2 as shown in FIG.
01 is described.

[0003] This power transmission device 201 has a part time 4
A transfer used in a wheel drive vehicle, wherein the driving force of the engine is transmitted from the transmission to the input shaft 203,
The power is transmitted to the propeller shaft on the front wheel side via an input transmission system 205, a chain transmission mechanism 207, and a power transmission system 209, and is transmitted by a front differential (a differential device that distributes the driving force of the engine to the left and right front wheels). Distributed to

The input side sprocket 211 of the chain transmission mechanism 207 is provided with a meshing clutch type intermittent mechanism 213, and the driving force of the engine is controlled by the input side sprocket 211, the intermittent mechanism 213, and the electromagnetic cup. The power is transmitted to the propeller shaft on the rear wheel side via the ring 215 and is distributed to the left and right rear wheels by a rear differential (a differential device for distributing the driving force of the engine to the left and right rear wheels).

The electromagnetic coupling 215 includes a clutch housing 217, a clutch hub 219, an inner shaft 221, a multi-plate type main clutch 223, a pressure plate 225, a disc spring 227, a ball cam 229, and the like.
Cam ring 231, flange 233, multi-plate pilot clutch 235, brake member 237, armature 2
39, an electromagnet 241 and the like.

The clutch housing 217 and the input sprocket 211 are connected and disconnected by a connecting and disconnecting mechanism 213.

[0007] The clutch hub 219 is spline-connected to the inner shaft 221, and the inner shaft 221 is connected to a propeller shaft on the rear wheel side via a flange 243.

The main clutch 223 is disposed between the clutch housing 217 and the clutch hub 219, and the pressure plate 225 is
17 so as to be movable.

The disc spring 227 is connected to the pressure plate 22.
5, the main clutch 223 is pressed and fastened.

The ball cam 229 is disposed between the pressure plate 225 and the cam ring 231, and the cam ring 231 is fixed to the flange 233.

The pilot clutch 235 includes a flange 2
The brake member 237 is arranged between the brake member 33 and the brake member 237, and is fixed to the transfer case 245.

The armature 239 is movably disposed on the brake member 237 with the pilot clutch 235 interposed therebetween.

The electromagnet 241 is connected to the transfer case 24.
5 to form an air gap 247 with the brake member 237.

When the excitation of the electromagnet 241 is stopped,
As described above, the main clutch 2 is
23 is pressed, and the coupling 215 is connected.

When the coupling 215 is connected, the driving force of the engine is sent to the rear wheels, so that the vehicle is driven in a four-wheel drive state.

As described above, in the four-wheel drive state, the electromagnet 2
Since the excitation of the motor 41 can be stopped, the load on the vehicle-mounted battery is reduced, and the fuel efficiency of the engine is improved.

On the other hand, when the electromagnet 241 is excited to attract the armature 239, the pilot clutch 235 is engaged, the torque between the clutch housing 217 and the clutch hub 219 is applied to the ball cam 229, and the generated cam thrust force is reduced. Disc spring 2 via plate 225
The pressing force of 27 is cancelled.

In this manner, the main clutch 223 is released, the connection of the coupling 215 is released, and the vehicle is brought into a two-wheel drive state.

When the exciting current of the electromagnet 241 is controlled while the coupling 215 is connected, the cam thrust force of the ball cam 229 changes due to the sliding of the pilot clutch 235, and the disc spring 227 presses the main clutch 223. Of the coupling changes, the coupling 215
The transmission torque of the rear wheel changes to adjust the driving force of the rear wheels.

[0020]

However, according to the conventional structure, the coupling 215 includes a disc spring 227.
Even in the two-wheel drive state where the pressing force is canceled, the clutch housing 217 of the main clutch 223 and the pressure plate 225 are connected by the pressing force of the disc spring 227, and the pressure plate 225 is
Ball cam 229, cam ring 231, flange 23
3, connected to a transfer case 245 via a pilot clutch 235 and a brake member 237.

Accordingly, the frictional resistance generated in the sliding portion between the clutch housing 217 and the pressure plate 225 and the disc spring 227 becomes the braking force of the vehicle, and the driving force is lost, thereby reducing the fuel consumption of the engine. Heat and abrasion may occur in these sliding parts, and the durability may be reduced.

Further, when the pilot clutch 235 is disposed between the clutch housing 217 and the flange 233, for example,
Since the drag torque is 15 and the driving force corresponding to the drag torque is transmitted to the rear wheels, the vehicle is not completely driven by two wheels.

The main clutch 223 having a large capacity
Requires a disc spring 227 having a large pressing force, and a large ball cam 229, a pilot clutch 235, and an electromagnet 241 are required to cancel the pressing force.

Therefore, the coupling 215 becomes larger and heavier, the in-vehicle mountability decreases, and the layout becomes difficult.

Moreover, if these capacities are insufficient,
The response at the time of switching to the two-wheel drive state may be delayed, and the turning performance of the vehicle may be reduced.

Further, the size of the electromagnet 241 increases the load on the battery, and the fuel efficiency of the engine decreases.

In addition, the electromagnet 241 and the armature 239
Between the brake member 237 and the pilot clutch 2
Since 35 is arranged, the loss of magnetic force is large, and the electromagnet 241 is further enlarged.

Accordingly, the present invention relates to a coupling for releasing connection by an electromagnet and a differential device for releasing connection of a differential limiting clutch by an electromagnet. The differential device has loss of driving force, lower fuel consumption, heat generation, and wear. It is an object of the present invention to provide a compact coupling and differential device having high durability, low magnetic force loss, compactness and high in-vehicle performance.

[0029]

According to a first aspect of the present invention, a coupling includes a pair of torque transmitting members, a main clutch disposed between the two torque transmitting members, a pilot clutch,
It is arranged in series with the pilot clutch between both torque transmitting members or between the torque transmitting member and the stationary side member. When the pilot clutch is connected, it operates by receiving the torque between the members and connects the main clutch. Cam and
An urging member and an electromagnet are provided, the urging member connects the pilot clutch, and the electromagnet cancels the pressing force of the urging member via the armature to release the connection of the pilot clutch. I do.

When the excitation of the electromagnet is stopped, the coupling according to the present invention having the negative operation configuration is connected by pressing the pilot clutch by the urging member to receive the transmission torque between the two torque transmission members. The main clutch is pressed by the thrust force and connected.

The coupling of the present invention is used for a four-wheel drive vehicle.
For example, in the case of the rear-wheel-side power transmission system, when the coupling is connected, the driving force of the engine is sent to the rear wheels, and the vehicle enters a four-wheel drive state. Etc. are improved.

On the other hand, when the electromagnet is excited, the armature moves to cancel the pressing force of the urging member, the connection of the pilot clutch is released, the thrust force of the cam disappears, and the main clutch is released to release the cup. The connection of the rings is released, and the vehicle enters a two-wheel drive state, thereby improving fuel efficiency of the engine.

Also, with the coupling connected,
When the exciting current of the electromagnet is controlled to change the attraction force of the armature, the pressing force of the urging member changes, the thrust force of the cam changes according to the slip of the pilot clutch, and the transmission torque of the coupling changes. The driving force of the rear wheels is adjusted.

By controlling the driving force distribution ratio between the front and rear wheels in this way, the controllability and stability of the vehicle during turning traveling are improved.

In addition, since the electromagnet is stopped in the four-wheel drive state, the load on the vehicle-mounted battery is reduced, and the fuel efficiency of the engine is improved.

In addition, the coupling of the present invention is different from the prior art in that the pilot member is pressed by the biasing member and the pressing force of the biasing member is canceled by the electromagnet.

Therefore, in a configuration in which the pilot clutch is disposed between the torque transmitting member and the stationary side member, the urging member does not slide with the peripheral member, so that a frictional resistance that becomes a braking force of the vehicle is generated. do not do.

Accordingly, loss of driving force, reduction of engine fuel efficiency, heat generation, wear, durability, and the like are prevented.

Further, in the configuration in which the pilot clutch is disposed between the two torque transmitting members, the drag torque by the urging member is prevented, so that the vehicle can be completely driven by two wheels.

Therefore, the turning performance of the vehicle and the fuel efficiency of the engine are improved.

Further, unlike the prior art in which the main clutch having a large capacity is pressed by the urging member, in the coupling of the present invention in which the pilot clutch having a small capacity is pressed by the urging member, the urging member having a large pressing force is used. Because it is unnecessary
A small electromagnet for canceling the pressing force is sufficient.

Accordingly, the coupling becomes lighter and more compact, the vehicle mountability is improved, and the layout becomes easier.

Even if a small-capacity electromagnet is used,
The response when switching to the wheel drive state is sufficiently fast, and the effect of improving the turning performance of the vehicle is large.

In addition, the size of the electromagnet reduces the load on the battery and improves the fuel efficiency of the engine.

The armature is moved by the electromagnet in addition to the magnetic armature being attracted by the electromagnet.
The armature may be configured as a magnet, and the armature is moved by a repulsive force due to the magnetic force of the electromagnet.

The coupling of the present invention may be arranged in the power transmission system on the front wheel side in addition to being arranged in the power transmission system on the rear wheel side of the four-wheel drive vehicle as described above.

Also in this case, when the coupling is connected, the vehicle enters a four-wheel drive state, and when the coupling is released, the vehicle enters a two-wheel drive state.

Further, the coupling of the present invention can be arranged between a front differential and one of left and right front wheels or between a rear differential and one of left and right rear wheels of a four-wheel drive vehicle.

Also in this case, when the coupling is connected, the vehicle is in a four-wheel drive state. When the connection is released, the transmission of the driving force to the wheels is stopped by the differential gears freely rotating differentially. The vehicle enters the two-wheel drive state.

According to a second aspect of the present invention, a case-like torque transmitting member which is rotated by a driving force of an engine, and a rotation of the case-like torque transmitting member is transmitted to a wheel side through a pair of shaft-like torque transmitting members. And a main clutch that limits the differential between the torque transmitting members, a pilot clutch, and a pair of torque transmitting members, or between a torque transmitting member and a stationary side member,
It is arranged in series with the pilot clutch, operates by receiving torque between the members when the pilot clutch is connected, includes a cam for connecting the main clutch, a biasing member, and an electromagnet, and the biasing member is a pilot clutch. Press
The electromagnet cancels the pressing force of the urging member via the armature to release the connection of the pilot clutch.

When the excitation of the electromagnet is stopped, the pilot clutch is pressed by the urging member, the cam is operated to connect the main clutch, and the differential of the differential mechanism is limited by the frictional resistance, so that the running performance on a rough road is restricted. In addition, the maneuverability and stability of the vehicle body are improved.

On the other hand, when the electromagnet is excited, the armature moves to cancel the pressing force of the urging member, the pilot clutch is released, the thrust force of the cam disappears, the main clutch is released, and the differential is released. It is permissible and the turning performance of the vehicle is improved.

When the exciting current of the electromagnet is controlled while the main clutch is connected, the cam thrust force changes according to the slip of the pilot clutch, and the differential limiting force of the main clutch changes. Maneuverability and stability of a running vehicle can be adjusted.

Further, the differential device according to the second aspect has the same effect as the coupling according to the first aspect by pressing the pilot clutch by the biasing member and releasing the connection of the pilot clutch by the electromagnet.

According to a third aspect of the present invention, there is provided the coupling or the differential device according to the first or second aspect, wherein the core of the electromagnet is arranged directly facing the armature, and The mach is connected to the pressing member disposed between the urging member and the pilot clutch via a connecting portion, and the same effects as those of the first and second aspects are obtained.

In this configuration, when the excitation of the electromagnet is stopped, the pilot clutch is pressed by the urging member via the pressing member, and when the electromagnet is excited, the pressing member connected to the armature via the connecting portion is activated. It moves, cancels the pressing force of the urging member, and releases the connection of the pilot clutch.

In addition, in this configuration, since the core of the electromagnet and the armature are directly opposed to each other, the brake member 237 is provided between the electromagnet 241 and the armature 239.
And a pilot clutch 235 are disposed, the loss of magnetic force is extremely small.

Therefore, it is possible to make the electromagnet more compact, with the result that the device becomes more compact, the vehicle mountability is improved, the layout becomes easier, the load on the battery is reduced, and the engine load is reduced. Fuel efficiency is improved.

According to a fourth aspect of the present invention, there is provided the coupling or the differential device according to the first to third aspects, wherein the biasing member is a disc spring. To get the effect.

In addition, the use of a thin disc spring as the biasing member makes the device compact in the axial direction, improves the on-board performance, and facilitates the layout.

[0061]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A coupling 1 (one embodiment of the present invention) will be described with reference to FIG.

This coupling 1 has the features of the first, third, and fourth aspects. Hereinafter, the left and right directions are coupling 1
Is the left and right direction of the part-time four-wheel drive vehicle using
The left side of FIG. 1 corresponds to the front of the vehicle. In addition, members and the like without reference numerals are not shown.

The power system of this part-time four-wheel drive vehicle is as follows:
It comprises an engine, a transmission, a transfer 3, a front differential, a front wheel side propeller shaft, left and right front axles and front wheels, a rear wheel side propeller shaft, a rear differential, left and right rear axles and rear wheels, and the like.

The coupling 1 is incorporated in the transfer 3, and controls connection and disconnection of the rear wheel side power transmission system and control of the driving force transmitted to the rear wheel side as described below.

The transfer 3 includes an input shaft, an input transmission system, a chain transmission mechanism, a power transmission system on the front wheel side, a meshing clutch type intermittent mechanism 5, a coupling 1, and the like.

The driving force of the engine is transmitted from the transmission to these input shafts, input transmission system, chain transmission mechanism,
The power is transmitted to the front-wheel-side propeller shaft via a front-wheel-side power transmission system, and is distributed from the front differential to the left and right front wheels via the front axle.

The intermittent mechanism 5 is provided between the input side sprocket of the chain transmission mechanism and the coupling 1, and the driving force of the engine is transmitted from the input side sprocket to the coupling 1 via the intermittent mechanism 5. Is done.

When the coupling 1 is connected, the driving force of the engine is transmitted from the coupling 1 to the propeller shaft on the rear wheel side, and is distributed from the rear differential to the right and left rear wheels via the rear axle. It becomes a driving state.

On the other hand, when the connection of the coupling 1 is released, the power transmission system on the rear wheel side is disconnected, and the vehicle is brought into a two-wheel drive state.

As shown in FIG. 1, the coupling 1 includes a clutch housing 7 (torque transmitting member), a clutch hub 9
(Torque transmitting member), inner shaft 11, multi-plate type main clutch 13, pressure plate 15, ball cam 17 (cam), cam ring 19, multi-plate type pilot clutch 21, brake member 23, pressing member 25, disc spring 27 (biasing member), armature 29, electromagnet 31,
It is composed of a controller and the like.

The clutch housing 7 is supported on the outer periphery of the clutch hub 9 via a ball bearing 33. The clutch hub 9 is connected to the outer periphery of the inner shaft 11 by a spline portion 35, and
The transfer case 39 (stationary side member) is supported by a bearing 37.

The inner shaft 11 has a front end supported by a transfer case 39 by a bearing, and a rear end supported by the transfer case 39 by a clutch hub 9 and a ball bearing 37. Also, the inner
The shaft 11 is connected to a rear wheel side propeller shaft via a joint.

The main clutch 13 is disposed between the clutch housing 7 and the clutch hub 9.

The pressure plate 15 is movably splined to the inner periphery of the clutch housing 7 and is axially positioned by a snap ring 41 mounted on the clutch housing 7.

The ball cam 17 is a pressure plate 1
5 and the cam ring 19. Further, between the cam ring 19 and the transfer case 39, a thrust bearing 4 receiving a cam reaction force of the ball cam 17 is provided.
3 are arranged.

The pilot clutch 21 is
9 and a brake member 23. Blaze
The pressure receiving member 4 of the pilot clutch 21
5 is fixed by a snap ring 47.

The outer periphery of the brake member 23 is spline-connected to a transfer case 39, and is positioned in the axial direction by a snap ring 49 mounted on the transfer case 39.

The pressing member 25 and the disc spring 27 are disposed between the wall 51 of the brake member 23 and the pilot clutch 21. The disc spring 27 presses the pilot clutch 21 via the pressing member 25. .

The armature 29 is arranged between the wall portion 51 of the brake member 23 and the electromagnet 31, and is connected to the connecting portion 5.
3 are connected to the pressing member 25. The connecting portion 53 penetrates a gap provided in the disc spring 27 and a through hole 55 provided in the wall 51.

In order to reduce the loss of the magnetic force of the electromagnet 31, the connecting portion 53 and the pressing member 25 are made of a non-magnetic material.

The electromagnet 31 is fixed to the transfer case 39, and an air gap 59 is formed between the core 57 and the armature 29 in the state of FIG. 1 in which the excitation of the electromagnet 31 is stopped. Have been.

The controller detects the turning traveling from the vehicle speed, the steering angle, the lateral G, etc., or performs the excitation of the electromagnet 31, the control of the excitation current, the stop of the excitation, and the like according to the road surface condition.

When the excitation of the electromagnet 31 is stopped, the pilot clutch 21 is pressed and connected by the disc spring 27, and the ball cam 17 is actuated by receiving the transmission torque between the clutch housing 7 and the clutch hub 9; The main clutch 13 is pressed by the thrust force, and the coupling 1 is connected.

When the coupling 1 is connected, the driving force of the engine is sent to the rear wheels, and the vehicle enters the four-wheel drive state.
The ability to travel on rough roads and the stability of the vehicle are improved.

On the other hand, when the electromagnet 31 is excited, a magnetic loop 61 is formed in the magnetic circuit, the armature 29 is attracted, and the pressing member 25 connected by the connecting portion 53 moves to push the disc spring 27. The pressure is canceled, the connection of the pilot clutch 21 is engaged, the thrust force of the ball cam 17 disappears, the main clutch 13 is released, and the connection of the coupling 1 is released.

When the connection of the coupling 1 is released, the vehicle enters the two-wheel drive state, and the fuel efficiency of the engine is improved.

When the exciting current of the electromagnet 31 is controlled to change the attraction force of the armature 29 with the coupling 1 connected, the pressing force of the disc spring 27 changes and the pilot clutch 21 slips. Accordingly, the thrust force of the ball cam 17 changes, the transmission torque of the coupling 1 changes, and the driving force transmitted to the rear wheels is adjusted.

When the driving force transmitted to the rear wheels is adjusted, the driving force distribution ratio between the front and rear wheels is changed, so that the steering and stability of the vehicle during turning are improved.

Thus, the coupling 1 is configured.

As described above, unlike the conventional example in which the main clutch 223 is pressed by the disc spring 227, the coupling 1 presses the pilot clutch 21 by the disc spring 27 and cancels the pressing force of the disc spring 27 by the electromagnet 31. It was configured to be.

Accordingly, the disc spring 27 does not slide with the peripheral members, and unlike the conventional example, there is no frictional resistance which becomes the braking force of the vehicle. Wear and reduced durability are prevented.

Further, the main clutch 22 having a large capacity
Unlike the conventional example in which the disc spring 3 is pressed by the disc spring 227, the disc spring 27 that presses the pilot clutch 21 having a small capacity does not require a large pressing force. Therefore, the electromagnet 31 that cancels the pressing force is also small. Is enough.

Therefore, the coupling 1 is lighter and more compact, and the mountability is improved.

Further, even when the electromagnet 31 having a small capacity is used, the response when switching to the two-wheel drive state is sufficiently fast, and the effect of improving the controllability and the like is large.

In addition, the miniaturization of the electromagnet 31 reduces the load on the battery and improves the fuel efficiency of the engine.

Further, since the core 57 of the electromagnet 31 and the armature 29 are arranged to face each other, the loss of magnetic force is extremely small as compared with the conventional example.

Accordingly, the size of the electromagnet 31 can be further reduced, and the coupling 1 can be further compacted, so that the on-board performance is improved, the load on the battery is reduced, and the fuel efficiency of the engine is improved.

Further, by using the thin disc spring 27, the coupling 1 is made compact in the axial direction, and the mountability on the vehicle is further improved.

Moreover, the layout of the coupling 1 and the transfer 3 is facilitated by the improvement of the on-board property as described above.

As described in the first aspect, in the present invention, the pilot clutch may be disposed between the two torque transmitting members.

In such a configuration, the drag torque is prevented by the biasing member, and the driving force is cut off. Therefore, the coupling can bring the vehicle into a complete two-wheel drive state. The dynamic rotation can be completely free, and in each case, the turning performance of the vehicle and the effect of improving the engine fuel efficiency are great.

Further, the invention of claim 2 is a differential device for limiting the differential rotation of the differential mechanism by the differential limiting force of the main clutch, and has the same effect as the coupling of claim 1.

Further, in the present invention, the biasing member is not limited to the disc spring, but other springs may be used.

[0104]

According to the first aspect of the present invention, since the pilot clutch is configured to be pressed by the urging member, no frictional resistance or drag torque is generated by the urging member, so that the driving force is lost and the engine fuel consumption is reduced. Reduction, heat generation, abrasion, durability deterioration and the like are prevented.

Further, since a small electromagnet is sufficient for canceling the pressing force of the urging member for pressing the pilot clutch having a small capacity, the coupling is lighter and more compact, and the mountability is improved. Layout becomes easy.

Further, by reducing the size of the electromagnet, the load on the battery is reduced, and the fuel efficiency of the engine is improved.

According to the differential device of the second aspect, the same effect as the coupling of the first aspect can be obtained by the configuration in which the pilot clutch is pressed by the urging member.

According to the third aspect of the present invention, the same effects as those of the first and second aspects are obtained, and the loss of the magnetic force is reduced and the size of the electromagnet is reduced.
The vehicle mountability is improved, the layout is simplified, the burden on the battery is reduced, and the fuel efficiency of the engine is improved.

According to the fourth aspect of the present invention, the same effects as those of the first to third aspects are obtained, and the use of a thin disc spring makes the device compact in the axial direction, further improves the vehicle mountability, and improves the layout. Becomes easier.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a coupling according to an embodiment.

FIG. 2 is a sectional view of a conventional example.

[Explanation of symbols]

 Reference Signs List 1 coupling 7 clutch housing (torque transmitting member) 9 clutch hub (torque transmitting member) 13 main clutch 17 ball cam (cam) 21 pilot clutch 25 pressing member 27 disc spring (biasing member) 29 armature 39 transfer -South (stationary side member) 53 Joint between armature and pressing member 57 Electromagnetic core

Claims (4)

[Claims] 1. A pair of torque transmitting members, a main clutch disposed between the two torque transmitting members, a pilot clutch, and between the two torque transmitting members, or between a torque transmitting member and a stationary side member. , Arranged in series with the pilot clutch, operates by receiving torque between the members when the pilot clutch is connected, includes a cam for connecting the main clutch, an urging member, and an electromagnet, and the urging member includes
A coupling for connecting a pilot clutch, wherein the electromagnet cancels the connection of the pilot clutch by canceling the pressing force of the urging member via the armature. 2. A case which is rotated by a driving force of an engine.
A torque transmitting member, a differential mechanism for distributing the rotation of the case torque transmitting member to the wheels via a pair of shaft torque transmitting members, and limiting a differential between the torque transmitting members. A main clutch, a pilot clutch, and a pair of torque transmitting members, or between a torque transmitting member and a stationary member, arranged in series with the pilot clutch,
When the pilot clutch is connected, it operates by receiving torque between the members, and includes a cam for connecting the main clutch, an urging member, and an electromagnet. The urging member presses the pilot clutch, and the electromagnet moves to the arc. A differential device for canceling the connection of a pilot clutch by canceling a pressing force of an urging member via a mache. 3. The invention according to claim 1, wherein the core of the electromagnet is disposed directly opposite to the armature, and the armature includes a biasing member and a pilot. A coupling or a differential device, wherein the coupling or the differential device is connected to a pressing member arranged between the clutch and a pressing member via a connecting portion. 4. The coupling or the differential device according to claim 1, wherein the biasing member is a disc spring.