JPH10226247A - Four-wheel drive system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent vibration of a four-wheel drive vehicle, and improve fuel consumption during switching to two-wheels traveling. SOLUTION: A two-way clutch 32 for performing transmission and interruption of the rotation of an input shaft 2 and a chain sprocket 18, and a rotation transmission device 12 having an electric current control means for controlling lock and release of the clutch 32, are incorporated in the inside of a transfer 3 for 4WD vehicle based on FR, which directly transmits the output from a transmission to a rear wheel driving shaft through the internal input shaft 21, and which can distribute power to a front wheel driving shaft through a silent chain 20. Thus, by controlling current flowing to the current control means depending on signals from a wheel speed sensor switching between 2WD and 4WD during the travel of a vehicle can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a FR-based 4
The present invention relates to a four-wheel drive system that switches between transmission and cutoff of a driving force on a drive path of a WD vehicle.

[0002]

2. Description of the Related Art A four-wheel drive vehicle (4WD) in which front and rear wheels are directly connected.
When a vehicle turns around a tight corner of a pavement, a so-called tight corner braking phenomenon occurs. As a means for solving this problem, the present applicant has proposed a rotation transmission device using a roller clutch and an electromagnetic coil.

FIG. 27 shows an example in which the above-mentioned rotation transmitting device is mounted on a vehicle. An FR 1 in which a front propeller shaft 5 and a rear propeller shaft 6 on a front wheel 4 side are branched by a transfer 3 connected to an engine 1 and a transmission 2.
In the base 4WD vehicle, a rotation transmission device 7 is mounted on the front propeller shaft 5, and the rotation transmission device 7 switches between 2WD traveling and 4WD traveling.

[0004]

By the way, when the rotation transmitting device is mounted on the front propeller shaft 5,
Since the front propeller shaft is shortened by the axial length of the rotation transmission device, the joint angle between the rotation transmission device and the front propeller shaft 5 becomes large, causing a large vibration during running, or the so-called unrotation of the propeller shaft 5. It is difficult to correct the balance.

[0005] In the conventional mounting position, for example,
The 4WD vehicle can switch and select the 2WD traveling mode, and even if it has a disconnection mechanism such as a hub clutch at each end of the front wheels, the front propeller shaft 5 cannot be stopped during 2WD traveling. Even if the clutch engagement of the conventional rotation transmitting device 7 is turned off, only the drive shaft 8 and the front differential 9 are stopped, and unless there is a separate drive disconnection mechanism such as a dog clutch in the transfer 3, the front propeller The shaft 5 rotates even during 2WD running, causing deterioration of fuel efficiency and vibration. Further, separately providing a drive disconnection mechanism such as a dog clutch in the transfer 3 is not rational since the rotation transmission device 7 has the drive disconnection mechanism, which leads to an increase in cost.

SUMMARY OF THE INVENTION It is an object of the present invention to prevent a vehicle from vibrating and to switch between 2WD driving modes by incorporating a rotation transmitting mechanism for electrically locking and freeing a two-way clutch using a current control means in a transfer. It is an object of the present invention to provide a four-wheel drive control system capable of improving the fuel efficiency of a vehicle.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the invention according to claim 1 transmits an output from a transmission directly to a rear-wheel propulsion shaft via an internal input shaft, and further comprises: A rotation transmission device for switching between 2WD and 4WD is mounted inside a FR-based transfer for a 4WD vehicle that can branch power to the propulsion shaft, and the rotation transmission device
A two-way clutch using an engagement element, and current control means for controlling lock and free of the two-way clutch;
A configuration is adopted in which the current to the current control means is controlled depending on the signal of the wheel speed sensor.

According to a second aspect of the present invention, a configuration is adopted in which a signal of a wheel speed sensor is input to a controller, and the controller controls a current to current control means in accordance with the content of the signal. .

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

In the first embodiment shown in FIGS. 1 to 11, FIG. 1 shows a four-wheel drive system using the four-wheel drive system of the present invention.
FIG. 2 is a cross-sectional view of a transfer in which a rotation transmission device is mounted, and FIG. 3 shows details of the rotation transmission device.

FIG. 1 shows that between front wheels 4, 4 and a front wheel propulsion shaft,
A rotation transmission device 12 is incorporated in a transfer 3 of an FR-based 4WD vehicle equipped with a hub clutch 10 for switching between coupling and disengagement of a front wheel and a front wheel propulsion shaft, whereby a conventional typical 4WD traveling mode ( 2WD, 4
In addition to WD-Hi and 4WD-Lo), a 4WD control auto mode and a 4WD lock mode are added.

As shown in FIGS. 1 and 2, an output from a transmission 2 connected to an engine 1 is transmitted to a rear propeller shaft 6 via a transfer 3, and diverges power to a front propeller shaft 5. I am getting it.

The transfer 3 includes a shaft 13 having an output shaft of the transmission 2 and a high / low select gear 14.
The high / low select gear 14 is a known technique, and is composed of a combination of a planetary gear set 15 and a select slide gear 16, and rotates in a one-to-one relationship when passing through the high gear. When transmitting the torque and passing through the low gear, the rotation is reduced and the torque increases.

A front output shaft 17 connected to the shaft 13 and the front propeller shaft 5
The chain sprockets 18 and 19 mounted on the respective shafts 13 and 17 are interlocked by a silent chain 20 so as to branch the power to the front wheel 4. The sprocket 18 for the shaft 13
And is coupled to the shaft 13 via the rotation transmitting device 12.

In the rotation transmitting device 12, a portion of the shaft 13 communicating with the rear propeller shaft 6 serves as an input shaft 21.
As shown in FIG. 3, a cam ring 22 serving as an inner member is coaxially fixed to the input shaft 21 so as to be non-rotatable by serration, and is externally fitted to the input shaft 21 via a bearing 23 so as to be rotatable. The cylindrical portion of the housing 24 serves as an outer ring 25 that fits over the cam ring 22, and the housing 24 is connected to the chain sprocket 18 and the serration 26 so as to rotate integrally.

As shown in FIG. 3B, a plurality of cam surfaces 27 are provided on the outer periphery of the cam ring 22, and the inner diameter of the outer ring 25 is a cylindrical surface 28, and a wedge-shaped space is formed between each cam surface 27 and the cylindrical surface 28. In addition, a retainer 29 that fits over the cam ring 22 is provided in the wedge-shaped space, and a roller 31 as an engaging element is incorporated in a pocket 30 formed at a position corresponding to each cam surface 27 of the retainer 29. Thus, a two-way clutch 32 is formed.

The roller 31 is, as shown in FIG.
When the cam ring 22 is located at the center neutral position with respect to the outer ring 25, a gap H is formed between the outer ring 25 and the cylindrical surface 28.
When the roller 31 is biased to one side of the wedge space by the retainer 29 as shown in FIGS. 8A and 8B, the roller 31 bites between the cam surface 27 and the cylindrical surface 28. In this state, the rotation of the cam ring 22 is transmitted to the outer race 25 so as to be turned on.

The other end of the switch spring 33, one end of which is locked to the retainer 29, is locked to the cam ring 22. As shown in FIG.
The holder 29 is supported and biased to a neutral position where it does not engage with.

An electromagnetic clutch 34 as current control means for controlling on / off of the two-way clutch 32 is provided at one side of the two-way clutch 32 between the input shaft 21 and the outer race 25, and a position at the other side. A wet multi-plate clutch 36 for transmitting the rotation of the input shaft 21 to the outer race 25 via a one-way clutch 35 is provided.

The electromagnetic clutch 34 non-rotatably fixes an electromagnetic coil 37 to a transfer case 38 with bolts 39 and the like, and the electrodes of the coil 37 are connected to an external controller (ECU) 40 through the transfer case 38. The ECU 40 includes a front wheel 4 and a rear wheel 4 as shown in FIG.
The number of rotations of a, the running mode selection switch 41, the signals input from the ABS operation switch 42 and the like are calculated and determined, and the current flowing through the electromagnetic coil 37 is controlled. As shown in FIG. 2, the rotation speed of the front wheel 4 is detected by a front speed sensor 43, and the rotation speed of the rear wheel 4a is detected by a rear speed sensor 44.

The rotor 45 which is externally fitted to the electromagnetic coil 37 so as to be rotatable becomes a friction flange which is fixed to the outer race 25 and rotates integrally therewith.
And an arm 46 fitted to the retainer 29 so as to be slidable in the axial direction and non-rotatable relative to the retainer 29 so as to overlap with the rotor 45 via an appropriate gap,
When the electromagnetic coil 37 is energized, the rotor 45 and the armature 46 are pressed against each other by magnetic force, and the outer race 25 and the retainer 29 are fixed in the rotation direction.

The wet multi-plate clutch 36 includes a plurality of inner plates 47 which are integrally movable with the one-way clutch 35 in the rotational direction and are axially movable, and a plurality of inner plates 47 which are integrally movable with the outer race 25 in the axial direction. The outer plates 48 are sequentially and alternately overlapped with each other, and are pressed against each other by a pressing spring 49 from one end in the overlapping direction. It is designed to run idle when relatively rotating in a direction corresponding to the forward direction.

The first embodiment of the present invention has the above-described configuration, and its operation will be described mainly with reference to the power transmission path diagrams shown in FIG. 4, FIG. 7, FIG. 9, and FIG.

FIG. 4A shows a power transmission path during 2WD forward travel. Power from the transmission passes through the high / low select gear 14 in the Hi range and is input to the input shaft 21 of the rotation transmission mechanism 12. You. When the rotation direction of the input shaft 21 is the forward direction of the vehicle, the one-way clutch 35 is mounted in the direction in which the input shaft 21 runs idle, and the wet multi-plate clutch 36 and the input shaft 21 are separated.

When 2WD is selected by the separately provided traveling mode selection switch 41, no current flows through the electromagnetic coil 37, and the two-way clutch 32 is neutral as shown in FIG. Since the state is maintained, the input shaft 21 and the outer ring 25 are separated.

Therefore, the power is not transmitted to the outer wheel 25, that is, the front wheel drive system, and is cut off. In the 2WD mode, since the hub clutch 10 is disengaged, the front propeller shaft 5, The front differential 9 and the drive shaft 8 can be stopped.

Next, FIG. 4B shows a power transmission path at the time of 2WD retreat. When the rotation direction of the input shaft 21 is the reverse direction of the vehicle, the one-way clutch 35 is locked,
1 and the outer ring 25 are torques (Tm
p). Therefore, the front propeller shaft 5 is rotated during traveling. 2 way clutch 3
2 holds the state of FIG. 5 as in the case of forward movement. However,
Since the hub clutch 10 is disengaged, no torque is applied to the front wheel 4. In addition, there is no problem in that dragging during retreat has a very small effect on fuel consumption and vibration.

Next, in the lock mode of the 4WD-Hi range, FIG. 7 (A) shows the forward mode and FIG. 7 (B) shows the reverse mode.
Shown in When the lock mode of the separately provided traveling mode selection switch 41 is selected, the rotation transmitting device 12 constantly supplies current to the electromagnetic coil 37, and the two-way clutch 3
2 is held in the state shown in FIGS. This FIG.
(A) is a state in which the retainer 29 and the outer ring 25 are
7, the input shaft 21 and the outer ring 2
When the roller 5 attempts to rotate relatively, the roller 31 bites in both directions. Therefore, from the transmission 3, the high / low select gear 14 in the Hi range
Is distributed to the front wheels by the two-way clutch 32 of the rotation transmission device 12 and can travel as a mechanically directly connected 4WD.

Next, in the lock mode of the 4WD-Lo range, FIG. 9 (A) shows a forward mode and FIG. 9 (B) shows a reverse mode.
Shown in The operation of the rotation transmission device 12 is the same except that the 4WD-Lo passes through the high / low select gear 14 in the Lo range.

Next, the control mode will be described. In the control mode, the power that has passed through the high / low select gear 14 in the Hi range is input to the input shaft of the rotation transmission device 12.

First, FIG. 10 shows the control mode during forward acceleration.
It is shown in (A). Rear wheel 4a due to acceleration on slippery roads
The (input shaft) slips, and the rotation of the rear wheel 4a exceeds the front wheel 4 (outer wheel) (“front wheel rotation speed <rear wheel rotation speed”).
When the rotational speed difference exceeds a set value, a current flows through the electromagnetic coil 37, the two-way clutch 32 is locked, and the front wheels 4
Power is transmitted to.

Next, in the control mode, forward traveling at a constant speed, deceleration,
FIG. 10B shows the state at the time of turning.

When the vehicle is traveling at a constant speed, the difference in the number of revolutions between the front and rear wheels is small and does not reach the set value, so that no current flows through the electromagnetic coil 37 and the two-way clutch 32 is in a free state.
Power is not transmitted to the front wheels 4.

When the vehicle is decelerated by the engine brake, the rotation of the rear wheel 4a (input shaft), which is directly connected to the engine, decreases and falls below the front wheel 4 (outer wheel). At this time, the current is not supplied to the electromagnetic coil 37, so the two-way clutch 32 is in a free state. However, if the vehicle is moving forward and the relationship such as “front wheel rotation speed> rear wheel rotation speed” is established, the one-way clutch 3
5 is a biting direction, the torque (about 3 to 6 kgfm) of the wet multi-plate clutch 36 is used as a deceleration torque for the front wheels 4.
Is transmitted to With this level of torque, the rear wheels 4a with engine brakes on slippery roads such as snowy roads
Can be prevented from slipping.

Similarly, at the time of turning, since the relationship of "front wheel rotation speed> rear wheel rotation speed" is established, a force for restraining the rotation difference between the front and rear wheels due to the torque of the wet multi-plate clutch 36 is applied between the front and rear wheels. Although it occurs, tight corner braking does not occur at such a small torque.

FIG. 11 (A) shows the reverse acceleration in the control mode.
Shown in At the time of acceleration on a slippery road surface, the relationship of “front wheel rotation speed <rear wheel rotation speed” is established as in the case of forward movement, so that the two-way clutch 32 is locked and power is transmitted to the front wheels 4.

FIG. 11 (B) shows the control mode when the vehicle is traveling backward at a constant speed, decelerating, and turning. At the time of reverse traveling at a constant speed, since the rotation speed difference does not reach the set value, no current flows through the electromagnetic coil 37, and the two-way clutch 32 is in a free state.
Power is not transmitted to the front wheels 4.

In deceleration such as engine braking when the vehicle is moving backward, the rotation of the rear wheel 4a (input shaft) directly connected to the engine is reduced, and is lower than that of the front wheel 4 (outer wheel). One-way clutch 3 between input shaft 21 and wet multi-plate clutch 36
5 is incorporated so that when the input shaft 21 is rotating in the backward direction of the vehicle, the input shaft 21 idles when the rotation of the input shaft 21 falls below the rotation of the outer ring (the wet multi-plate outer plate is connected). Therefore, in the case described above, the front wheel 4
No power is transmitted to the vehicle. Therefore, in the control mode,
Only when the vehicle is backing up, the engine brake torque is
Is not allocated. However, it is rare that an engine brake is required at the time of retreat, and usually there is no problem because a foot brake is also used.

When the vehicle turns backward, the same rotational relationship as when the engine is braked ("front wheel speed> rear wheel speed") occurs, and the rotation direction is the vehicle backward direction. 35 is also free and does not transmit power to the front wheels, avoiding tight corner braking.

On the other hand, the anti-lock brake system (A
BS) operates, an operation signal is detected from the ABS controller, and the electromagnetic coil 37 in the rotation transmission mechanism 12 is detected.
Control so that no current flows. By doing so, the two-way clutch 32 is held in a free state (FIG. 5), so that the power circulation between the front and rear wheels during the ABS operation is 3-6 kg of the wet multi-plate clutch 36.
fm. This amount of torque (resistance)
The effect on the operation of the ABS is minimal.

That is, in the control mode, a sufficient driving force is transmitted by the two-way clutch 32 at the time of forward movement and at the time of reverse movement during acceleration, but at the time of forward movement at the time of constant speed running, engine braking, turning, and ABS operation. Only in this case, the torque of the wet multi-plate clutch 36 is transmitted to the front wheels 4.

Further, the torque of the wet type multi-plate clutch 36 is set to a magnitude sufficient to distribute the engine braking torque to the front wheels, and to a magnitude that does not cause tight corner braking.

In the rotation transmitting device 12, the wet multi-plate clutch 36 can be eliminated. In this case, a sensor detects that the rear wheel slips during the operation of the engine brake and locks the two-way clutch 32. You can make it happen. (The same applies to the following embodiments.) Next, FIGS. 12 and 13 show a second embodiment of the rotation transmitting device. The 4WD vehicle according to the second embodiment is a case where an intermittent device such as a hub clutch for stopping the front differential 9 and the propeller shaft 5 when 2WD is selected is not provided. This is seen in 4WD vehicles that emphasize cost. The rotation transmission device is such a 4WD
It can also handle layouts. FIG. 13 shows a cross-sectional view of the transfer. The difference from the first embodiment is that a one-way clutch is not required between the wet multi-plate clutch 36 and the input shaft 21. The control and operation of the rotation transmission device 12 are almost the same as those of the first embodiment, and therefore will not be described. However, the difference from the first embodiment is that the front drive system rotates without stopping even in the 2WD mode.
The wet multi-plate clutch 36 includes the input shaft 21 (rear wheel) and the outer wheel 25.
2W to constantly transmit friction torque between (front wheels)
Even in the D mode, the torque of the wet multi-plate clutch 36 is distributed to the front wheels 4. However, since the torque during acceleration is small, it is almost equal to 2WD.

FIG. 14 is a sectional view of a transfer which is a third embodiment of the rotation transmitting device. In the first embodiment, the front propeller shaft 5 is rotated in the 2WD mode only when the vehicle retreats. In the third embodiment, the front output shaft 17 and the front sprocket 19
The dog clutch 50 is provided between the
Is selected, the clutch 50 is disengaged, and the torque of the wet multi-plate clutch 36 of the rotation transmitting device 12 is not transmitted to the front propeller shaft 5 at all.
As a result, no torque is transmitted to the front wheels during 2WD. Also, in the third embodiment, the internal one-way clutch is not required in the third embodiment.

At the time of 4WD (lock mode, control mode), the dog clutch 50 is engaged, and the operation and control contents are the same as those of the second embodiment, so that the description is omitted.

Next, FIG. 15 shows a fourth embodiment of the rotation transmitting device. As shown in the sectional view of FIG. 15, in the first to third embodiments, the chain sprocket 18 and the input shaft 2 connected to the outer race 25 of the rotation transmission device 12 are used.
1 are formed with sprockets 51 and 52,
When the WD low gear is selected, the slide gear 16 is moved to fit the two with the sprockets 51 and 52. As a result, the drive system of the front wheel 4 and the rear wheel 4a is directly connected by the sprocket fitting, so that power does not pass through the two-way clutch 32. In the first to third embodiments, in the 4WD lock mode, it is necessary to keep the current flowing through the electromagnetic coil 37 of the rotation transmission device 12.
In this embodiment, since power does not pass through the rotation transmitting device, there is no need to supply a current to the electromagnetic coil 37, so that it is economical.

In the fourth embodiment, 4 W
When the D low gear is selected, the input torque increases by the reduction ratio, but at this time, the large torque does not pass through the rotation transmission device 12, so that the allowable torque of the rotation transmission device 12 may be small, and it is lighter and more compact. Can be

The structure of the two-way clutch 32 used in each of the first to fourth embodiments is shown in FIG.
6 (A) and 6 (B), the outer ring 25 has a polygonal cam surface 2.
7. A structure having a cylindrical surface 28 on the inner ring 22a side may be adopted. At this time, the suction force of the electromagnetic clutch 34 presses the retainer 29 and the inner race 22a (in FIG. 16, the inner race 22a and the input shaft 21 are integrated). Further, the two-way clutch 32 may use a sprag instead of the roller 31.

Here, in the rotation transmission device 12 in each of the above-described first to fourth embodiments, a wet multi-plate clutch 36 is added between the input shaft 21 and the output outer wheel 25 in parallel with the two-way clutch 32. When the vehicle is normally traveling at a constant speed, the vehicle is in a rear wheel drive (2WD) state.

When the vehicle accelerates, when the slip of the rear wheel is sensed, a current flows through the electromagnetic clutch 34, the 2-way clutch 32 is locked to 4WD, and a low μ is applied.
When a sudden engine brake is applied on the road, the deceleration torque of the engine brake does not pass through the two-way clutch 32 but is also appropriately distributed to the front wheels 4 through the wet multi-plate clutch 36.

However, since the wet multi-plate clutch 36 is constantly pressed constantly by the elastic member, lubricating oil does not easily enter the friction surface, and the durability is low. In addition, since the drag acts between the front and rear wheels even while the vehicle is turning, the steering may become heavy and cause vibration, and the wet multi-plate clutch 36 takes an axial length of the rotation transmission device. .

Therefore, in the fifth embodiment shown in FIGS. 17 to 26, the wet multi-plate clutch 36 of the rotation transmitting device 12 in each of the first to fourth embodiments is eliminated, and the wet multi-plate clutch is removed. This is a simple, compact and inexpensive rotation transmission device in which the function of distributing the deceleration torque by the engine brake to the front wheel 4 side, which has been the role of 36, is replaced by locking the two-way clutch 32 by electric control.

FIG. 17 shows an FR-based 4WD drive layout incorporating the rotation transmitting device 12 of the fifth embodiment.
FIG. 18 is a cross-sectional view of a transfer equipped with the rotation transmitting device, and FIG. 19 is a detailed view of the transfer, specifically, FIG.
3 except that the wet multi-plate clutch 36 is eliminated from the outer race 25 of the first embodiment shown in FIG. 3, and the rotation transmission device 12 is a typical part-time four-wheel. Drive mode (2WD, 4WD-H)
i, 4WD-Lo), a 4WD control mode and a 4WD lock mode by this device are added.

As shown in FIG. 18, the output from the transmission passes through the high / low select gear 14 and extends to the rear propeller shaft 6. The high / low select gear 14 is a known technology, and comprises a planetary gear,
When passing through the high gear, the rotational torque is transmitted in a one-to-one relationship, and when passing through the low gear, the rotation is reduced and the torque increases.

The shaft connected to the rear propeller shaft 6 is the input shaft 21 of the rotation transmitting device 12. Rotation transmission device 1
The second outer wheel 25 is connected by serrations 26 to a chain sprocket 18 for splitting power to the front wheels. The sprocket 18 is rotatably fitted to the input shaft 21.

The cam ring 22 of the rotation transmitting device 12 is fixed to the input shaft 21 by serrations.
, A cage 29 and a roller 31 are provided to form a two-way clutch 32.

As shown in FIG. 19, the electromagnetic coil 37 is non-rotatably fixed to the transfer case 38 with bolts 39 and the like, and the electrodes of the electromagnetic coil 37 are connected to the external controller 40 (ECU) through the transfer case 38.

The external controller 40 (ECU)
7, the front / rear rotation speed, mode selection switch 41, AB
Each signal input from the S operation signal 42 and the like is calculated and determined, and the current flowing through the electromagnetic coil 37 of the rotation transmission device 12 is controlled.

First, the 2WD mode of the transfer incorporating the rotation transmitting device 12 will be described. FIG. 20 shows the principle of the rotation transmission device 12 and the power transmission path at the time of 2WD. Power from the transmission passes through the Hi range gear and is input to the input shaft 21 of the rotation transmission device 12.

Further, when 2WD is selected by the separately provided mode selection switch 41, no current flows through the electromagnetic coil 37, and the two-way clutch 32 is connected as shown in FIG. Since the neutral state is maintained, the input shaft 21 and the outer ring 25 are separated.

Accordingly, power is not transmitted to the outer wheel 25, that is, the front wheel drive system, and is disconnected. In the 2WD mode, the connection of the hub clutch 10 is disconnected.
1, the front propeller shaft 5, the front differential 9, and the drive shaft 8 can be stopped even while the vehicle is running, so that fuel-efficient running can be achieved.

Next, a power transmission path in the lock mode of the 4WD-Hi range is shown in FIG. When the lock mode of the separately provided mode selection switch 41 is selected, the rotation transmitting device 12 constantly supplies a current to the electromagnetic coil and holds the two-way clutch 32 in the state shown in FIGS. 8A and 8B. I do. 8A and 8B, since the retainer 29 and the outer ring 25 receive frictional resistance through the armature 46 by the attraction force of the electromagnetic coil 37, the input shaft 21 and the outer ring 25 try to rotate relative to each other. Then, the rollers 31 bite in both directions. Therefore, the power that has passed from the transmission through the Hi range gear of the high / low select is also distributed to the front wheel side by the two-way clutch 32 of the rotation transmission device 12 and can travel as a mechanically directly connected 4WD.

Next, the lock mode of the 4WD-Lo range is shown in FIG. 4WD-Lo is Lo
Except for passing through the range gear, the lock mode of the Hi range and the operation of the rotation transmitting device are the same.

Next, the control mode will be described. In the control mode, the power that has passed through the Hi range gear is input to the input shaft 21 of the rotation transmission device 12.

First, FIG. 23 (A) shows the time of acceleration in the control mode.
Shown in Rear wheel (input shaft) for acceleration on slippery roads
Slips, and the rotation of the rear wheel exceeds the front wheel (outer wheel) (“front wheel rotation speed <rear wheel rotation speed”). When the rotational speed difference exceeds a set value, a current flows through the electromagnetic coil 37, the two-way clutch 32 is locked, and power is transmitted to the front wheels.

Next, FIG. 23B shows the control mode when the vehicle is traveling at a constant speed and when turning. When the vehicle is traveling at a constant speed, the rotational speed difference between the front and rear wheels is small and does not reach the set value. Therefore, no current flows through the electromagnetic coil 37, the two-way clutch 32 is in a free state, and power is not transmitted to the front wheels.

Next, the case where the engine brake is applied will be described. When the engine brake is applied to the vehicle, the torque of the engine brake is directly transmitted to the rear wheels via the input shaft 21 of the rotation transmission device. If the road surface is a high μ road such as asphalt, the rear wheels will not slip with relatively weak torque such as engine braking. Therefore, in this situation, control is performed so that no current flows through the electromagnetic clutch 34 (FIG. 24A). Therefore, during engine braking on a high μ road, the two-way clutch 32 does not lock, and tight corner braking does not occur.

On the other hand, on a low μ road such as a snowy road, the rear wheel may slip even with the engine brake torque alone, and the rear wheel tends to rapidly decelerate. At this time, the rotation transmission device 12 supplies a current to the electromagnetic clutch 34 to cause the two-way clutch 3
24, the rear wheel is prevented from slipping, and the engine brake torque can also be distributed to the front wheel 4 (FIG. 24).
(B)).

FIG. 25 shows a flowchart of the control at the time of engine braking. This control method calculates the differential value of the rotation speed of the front wheel (outer wheel side) and the rear wheel (input shaft side), the rear wheel slips in the deceleration direction, and the deceleration (rear wheel differential value) is the deceleration of the front wheel. When the value exceeds the value (front wheel differential value) and reaches the set value, 2
This locks the way clutch 32 to 4WD.

This can be expressed by the following equation. _{| DV R / dt-dV F} / dt |> D 1 V R: rear wheel rotation speed V _F: front wheel rotational speed D _1: setpoint.

FIGS. 26 (A) to 26 (D) show the rotation speed waveforms at the time of engine braking on the high μ road and the low μ road, and their front and rear wheel rotation speed differential values (deceleration). In the case of a low μ road, the rear wheel differential value increases due to the deceleration slip of only the rear wheel, and exceeds the set value.
Current flows through 4 and becomes 4WD. On a high μ road, there is almost no slippage due to engine braking, so that no current flows and 2WD remains.

The structure of the two-way clutch 32 may be such that the outer ring has a polygonal cam surface and the inner ring has a cylindrical surface as shown in FIG. At this time, the suction force of the electromagnetic clutch presses the retainer and the inner ring (in the figure, the inner ring and the input shaft are integrated).

In each of the first to fifth embodiments,
The outer wheel 25 is set as the output side (front wheel).
5 may be connected to an input shaft, engine power may be input from an outer wheel, and the inner wheel side may be connected to a chain sprocket.

Further, it is within the scope of the present invention to mount the rotation transmission device 12 at a position used for intermittent power between the front output shaft 17 and the front sprocket 19.

[0075]

As described above, according to the present invention, the rotation transmitting device incorporated in the transfer is formed by the two-way clutch using the engaging element and the current control means for controlling the lock and free of the clutch. Since the current to the current control means is controlled depending on the signal of the wheel speed sensor, the switching between 2WD and 4WD during the running of the vehicle can be quickly performed by electrical control, and the rotation transmission device is used. Thus, 2WD, LOCK, and control modes can be selectively used, and the number of drive modes that can be selected by the driver can be increased.

[Brief description of the drawings]

FIG. 1 is a plan view showing a layout of a 4WD drive vehicle incorporating a rotation transmission device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of a transfer incorporating a rotation transmission device.

FIG. 3A is an enlarged cross-sectional view of a main part of the above,
(B) is a cross-sectional view along the arrow bb of (A).

4A is an explanatory diagram showing the principle of a rotation transmission device and a power transmission path at the time of 2WD forward movement, and FIG. 4B is an explanatory diagram of the same at the time of 2WD backward movement.

FIG. 5 is an enlarged sectional view of a main part showing a neutral state of the two-way clutch.

FIG. 6 is a plan view showing a 2WD traveling of the 4WD drive vehicle.

FIG. 7A is an explanatory view showing the principle of a rotation transmission device and a power transmission path when the vehicle travels forward by 4WD-Hi, and FIG.
Explanatory diagram at the time of D-Hi retreat

FIGS. 8A and 8B are enlarged sectional views showing a locked state of a two-way clutch.

FIG. 9A is an explanatory view showing a power transmission path when the 4WD-Lo moves forward, and FIG. 9B is an explanatory view showing a power transmission path when the 4WD-Lo moves backward.

10A is an explanatory diagram illustrating a power transmission path during forward acceleration in the 4WD control mode, and FIG. 10B is an explanatory diagram illustrating a power transmission path during forward deceleration in the 4WD control mode.

11A is an explanatory diagram showing a power transmission path during 4WD control mode reverse acceleration, and FIG. 11B is an explanatory diagram showing a power transmission path during 4WD control mode reverse deceleration.

FIG. 12 is a plan view showing a layout of a 4WD drive vehicle incorporating the second embodiment of the rotation transmission device.

FIG. 13 is a sectional view showing a transfer according to the third embodiment;

FIG. 14 is a cross-sectional view of a transfer showing a third embodiment of the rotation transmitting device.

FIG. 15 is a sectional view of a transfer showing a fourth embodiment of the rotation transmitting device.

16A is an enlarged cross-sectional view of a main part showing another embodiment of a two-way clutch of a rotation transmission device, and FIG.
Sectional view along arrow bb

FIG. 17 is a plan view showing a layout of a 4WD drive vehicle incorporating the fifth embodiment.

FIG. 18 is a cross-sectional view of a transfer incorporating the rotation transmission device of the above.

FIG. 19 is an enlarged sectional view of a main part of the above.

FIG. 20 is an explanatory view showing the principle of a rotation transmission device and a power transmission path at the time of 2WD.

FIG. 21 is a plan view showing a layout during 2WD running.

22A is an explanatory diagram illustrating a power transmission path at the time of 4WD-Hi, and FIG. 22B is an explanatory diagram illustrating a power transmission path at the time of 4WD-Lo.

FIG. 23A is an explanatory diagram showing a power transmission path during 4WD control mode acceleration, and FIG. 23B is an explanatory diagram showing a power transmission path during 4WD control mode constant speed turning.

24A is an explanatory view showing a power transmission path on a high μ road at the time of 4WD control mode engine braking, and FIG.
Explanatory diagram showing a power transmission path on a low μ road during WD control mode engine braking

FIG. 25 is a flowchart showing lock control when an engine brake is applied.

26A is a diagram illustrating a wheel speed during engine braking on a high μ road, FIG. 26B is a diagram illustrating a difference between wheel speed differential values during engine braking on a high μ road, and FIG. 26C is a diagram illustrating an engine on a low μ road. (D) is an explanatory diagram showing the difference between the wheel speed differential values during engine braking on a low μ road and (D), respectively.

FIG. 27 is a plan view showing a vehicle-mounted embodiment of a conventional rotation transmission device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 3 transfer 4 front wheel 5 front propeller shaft 12 rotation transmission device 13 shaft 14 high / low select gear 17 front output shaft 18, 19 chain sprocket 20 silent chain 21 input shaft 22 cam ring 24 housing 25 outer ring 27 cam surface 28 cylindrical surface 29 retainer Reference Signs List 30 pocket 31 roller 32 2-way clutch 33 switch spring 34 electromagnetic clutch 35 one-way clutch 36 wet multi-plate clutch 37 electromagnetic coil 38 transfer case 45 rotor 46 amateur 47 inner plate 48 outer plate 49 pressing spring

Claims (2)

[Claims] An output from a transmission is directly transmitted to a rear wheel propulsion shaft via an internal input shaft, and power is branched to a front wheel propulsion shaft. A rotation transmission device for switching the 4WD is mounted, and the rotation transmission device uses an engagement element.
A four-wheel clutch comprising a way clutch and current control means for controlling the locking and freeing of the two-way clutch, and controlling the current to the current control means depending on a signal from a wheel speed sensor. Drive system. 2. The four-wheel drive system according to claim 1, wherein a signal from the wheel speed sensor is input to the controller, and the controller controls the current to the current control means according to the content of the signal.