JP2001206092A - Driving force distribution device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving force distribution device capable of continuous control of clutch pressure and reduce the cost by reducing the number of part items. SOLUTION: When a control circuit 35 supplies electric current corresponding to the selected mode to a pump motor 33 based on a mode selection signal, an oil pump 32 supplies hydraulic fluid 30 of an oil pressure corresponding to the selected mode to a piston 26. The piston 26 presses a multiple disc clutch 23 through a pressing member 25 by the hydraulic fluid 30. The drive force distribution device 1 distributes the drive torque from an engine to front wheels and rear wheels at the distribution ratio corresponding to the mode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving force distribution device which is applied to a four-wheel drive vehicle and distributes a driving force from a prime mover to a front wheel and a rear wheel at a predetermined distribution ratio. The present invention relates to a driving force distribution device capable of reducing the number of parts and reducing costs.

[0002]

2. Description of the Related Art In recent years, with the diversification of automotive applications, the number of four-wheel drive vehicles has increased rapidly. Conventionally, in this four-wheel drive vehicle, a driving force distribution device that distributes driving force generated by an engine to front wheels and rear wheels by hydraulic pressure has been used.

FIG. 9 shows a basic configuration of a four-wheel drive vehicle to which the conventional driving force distribution device is applied. The driving force generated by the engine 101 is transmitted to the driving force distribution device 1 via the transmission 102 and the center drive shaft 103, and is transmitted from the hydraulic unit 5 to the predetermined hydraulic pressure by the multi-plate clutch 23 built in the driving force distribution device 1. And transmits the driving force from the engine 101 at a predetermined distribution ratio to the rear wheels 105 via the center drive shaft 103 and the differential 104, and to the front wheels 107 via the front drive shaft 106 and the differential 104. Has communicated. The control of the hydraulic pressure to the multi-plate clutch 23 is performed by controlling the hydraulic unit 5 by the control circuit 6.

FIG. 10 shows the conventional driving force distribution device 1 shown in FIG. The driving force distribution device 1 includes a device main body 2A
And a hydraulic circuit 5 connected to the apparatus main body 2A via a pipe 5a, and a control circuit 6 for controlling the hydraulic unit 5. The multi-plate clutch 23 is provided in the apparatus main body 2A.
And a pressing member 25 for pressing the multi-plate clutch 23, a lever 13 for pressing the pressing member 25, and a piston 14 for rotating the lever 13.

The hydraulic unit 5 includes an oil pump 50 for pumping hydraulic oil, a pump motor 51 for driving the oil pump 50, and an accumulator 53 for accumulating hydraulic oil pumped from the oil pump 50 via a check valve 52.
A pressure switch 54 for detecting line pressure, a pressure control valve 56 connected via a filter 55 for controlling line pressure, a relief valve 57 that operates at a predetermined pressure or higher to release hydraulic oil, Control valve 56 and relief valve 57
And a reservoir tank 58 for receiving hydraulic oil returning from the storage tank.

[0006] The driving force distribution device 1 configured as described above.
When the oil pump 50 feeds hydraulic oil by driving the pump motor 51, the hydraulic oil is accumulated in the accumulator 53, and the pump switch 51 is turned on / off by the pressure switch 54 so that the line pressure falls within a predetermined pressure range.
OFF control is performed. Hydraulic oil, which is pressure-fed from the oil pump 50 and is controlled to a predetermined pressure range, is partially returned to the reservoir tank 58 in accordance with the opening degree of the pressure control valve 56 controlled by the control circuit 6, so that the piston 14
Hydraulic pressure of the hydraulic oil supplied to the
3 (clutch pressure) is adjusted. in this way,
By controlling the opening of the pressure control valve 56, the clutch pressure can be continuously controlled, and optimal power distribution can be realized under various running conditions.

[0007]

However, according to the conventional driving force distribution device, the pump motor is fully rotated to keep the line pressure constant, and the hydraulic pressure supplied to the piston is reduced by reducing the pressure by the pressure control valve. Since the control is performed, there is a problem that the number of parts is increased and the cost is increased.

Accordingly, an object of the present invention is to provide a driving force distribution device capable of continuously controlling the clutch pressure, reducing the number of parts and reducing the cost.

[0009]

According to the present invention, in order to achieve the above object, a multi-plate clutch is pressed by a pressing member with a predetermined pressing force, so that the driving force from the prime mover is changed according to the predetermined pressing force. In the driving force distribution device that transmits to the front wheels and the rear wheels at the distribution ratio, a piston that presses the multi-plate clutch via the pressing member, and a hydraulic fluid that generates a pressing force that presses the pressing member against the piston are provided. A pump for supplying the piston chamber with the pump, a motor for driving the pump to supply the hydraulic fluid to the piston chamber, and control means for outputting a control signal corresponding to the distribution ratio to drive the motor. A driving force distribution device is provided. According to the above configuration, the pressure liquid of the pump is controlled by the control signal to the motor, and the pressing force (clutch pressure) to the multi-plate clutch is controlled via the pressing member.

[0010]

FIG. 1 shows a driving force distribution device according to a first embodiment of the present invention. This driving force distribution device 1
Has an input shaft 20A in which drive torque is input from an engine 101 shown in FIG. 9 via a transmission 102 and a center drive shaft 103, and is disposed coaxially with the input shaft 20A. The rear wheel output shaft 20B and the front wheel output shaft 20C are accommodated. These input shaft 20A, rear wheel output shaft 2
0B and the output shaft 20C for the front wheel are ball bearing 2
1A supports the case 2.

On the outer periphery of the rear wheel output shaft 20B, a drive sprocket 22A non-coupled and supported by the rear wheel output shaft 20B, a clutch housing 24 for accommodating the multi-plate clutch 23, and a multi-plate clutch 23 Member 25 for pressing or releasing the pressure member, and piston 2 for pressing the pressing member 25
6 is provided. The multi-plate clutch 23 is composed of a plurality of clutch disks 23a and a pusher plate 23b that transmit drive torque by making surface contact with each other. The clutch housing 24 accommodates the clutch disc 23a and accommodates the drive sprocket 22A.
And an inner housing 24b which accommodates the pusher plate 23b and is supported by the rear wheel output shaft 20B. A clutch spring 27 is disposed between the inner housing 24b and the pressing member 25 so that the clutch disc 23a and the pusher plate 23b are brought into a non-contact state when the multi-plate clutch 23 is released. The piston 26 is a cylinder portion 26b integrated with the case 2.
And a piston body 26a that moves in the cylinder 26b by the hydraulic oil 30. In order to allow the piston body 26a to transmit the pressing force to the rotating pressing member 25, the pressing member 25 and the piston body 2
The needle bearing 21B is disposed between the needle bearing 21B and the needle bearing 21A.

A driven sprocket 22B is provided on the outer periphery of the front wheel output shaft 20C, and the driven sprocket 22B and the drive sprocket 22A
2C is wound.

The device 1 has a hydraulic oil supply mechanism 3 for supplying hydraulic oil to the piston 26. The hydraulic oil supply mechanism 3 sucks and pressurizes the hydraulic oil 30 stored in the lower portion 2 a of the case 2 through a strainer 31.
For example, an oil pump 32 such as a trochoid pump,
An oil pump 3 is disposed between the pump motor 33 for driving the oil pump 32 and the oil pump 32 and the piston 26.
And a control circuit 35 for controlling the pump motor 33. The supply path 34 and the supply port 34a form a supply oil path for the hydraulic oil 30 pumped by the pump 2.

The piston 26 is formed by a cylinder portion 26 b integrated with the case 2 and a cylinder portion 2 by hydraulic oil 30.
The piston body 26a moves in the inside of the piston body 6b, and a packing provided on the piston body 26a to prevent the leakage of the hydraulic oil 30 is provided. The orifice 36a is provided at the top of the piston chamber. Providing the orifice 36a at the uppermost portion makes it difficult for air to accumulate in the piston chamber, thereby improving responsiveness. The hydraulic oil 30 returning from the orifice 36a is
It is stored in the lower part 2 a of the case 2 through the discharge path 28.

The control circuit 35 includes a 4WD mode, a 2WD mode, and a full-time 4
The pump motor 33 is controlled so that the oil pump 32 generates a corresponding oil pressure based on a mode selection signal such as a WD mode (a mode in which the oil pressure P is supplied to the piston 26 according to the road surface condition).

FIG. 2A shows a hydraulic circuit of the hydraulic oil supply mechanism 3. In the supply passage 34 between the oil pump 32 and the piston chamber 26d, a check valve 37 and a filter 38 are provided.
Is provided in the supply path 34 between the check ring 37 and the piston chamber 26d. The piston pressure quick release valve 39 is provided with the oil pump 32 side of the check ring 37 and the piston. Pilot pressure is introduced from the chamber 26d side via the pilot pressure circuits 39a and 39b, and the forced release valve 40 is connected to the pilot pressure circuit 39b on the oil pump 32 side to supply the oil between the oil pump 32 and the check valve 37. In path 34, orifice 36b
Are connected. 26c is a piston main body 26a.
It is a packing provided in. When the pump motor 33 is stopped, the oil in the hydraulic circuit is not released by the backflow prevention valve 37, so that it is possible to prevent air from being trapped in the hydraulic circuit, thereby preventing responsiveness from deteriorating. The supply port 34a shown in FIG.
It is provided above 6d. As a result, the check valve 37
However, even if a failure occurs, the amount of the hydraulic oil 30 that can escape can be reduced.

FIG. 2B shows a block 41 of FIG.
Is shown. The block 41 has a block body 410 made of metal or plastic.
The supply path 34, the orifice 36b, the pilot pressure circuits 39a and 39b, the check valve 37, and the quick release valve 39 are provided.

The piston pressure quick release valve 39 is provided with a hydraulic oil 30 from a pilot pressure circuit 39a on the piston chamber 26d side.
From the discharge path 39c for discharging the oil to the outside, and the pilot pressure circuit 39b on the oil pump 32 side.
The block 39 is provided with an outlet 39d for discharging
10

The forcible release valve 40 includes a rod 400 for opening and closing the discharge port 39d of the piston pressure rapid release valve 39, a preload spring 402 for pressing the rod 400 toward the discharge port 39d, and a rod against the spring force of the preload spring 402. The coil 4 that moves the spring 400 toward the preload spring 402 and opens the outlet 39d.
01.

FIG. 3 shows the relationship between the oil pressure P generated by the oil pump 32 and the current Im supplied to the pump motor 33. As shown in the figure, there is a proportional relationship between the oil pressure P generated by the oil pump 32 and the current Im supplied to the pump motor 33. The relationship between the oil pressure P and the current Im is stored in a memory, and the control circuit 35 outputs the current Im supplied to the pump motor 33 based on the stored contents of the memory and a mode selection signal from a select lever (not shown). By controlling, the hydraulic pressure supplied to the piston 26 can be controlled.

Next, the operation of the apparatus 1 will be described. A case where the driver operates a select lever (not shown) to select the full-time 4WD mode will be described. The select lever outputs a mode selection signal indicating the full-time 4WD mode to the control circuit 35. Control circuit 35
Controls the current supplied to the pump motor 33 so as to supply the corresponding oil pressure to the piston 26 based on a signal from a sensor for detecting a road surface condition. For example, the control circuit 3
5 is based on a signal from a sensor that detects a road surface condition,
When it is determined that the vehicle should travel at 4WD in which the degree of connection between the front and rear wheels is strong due to poor road surface conditions, the current supplied to the pump motor 33 is controlled so that the corresponding hydraulic pressure is supplied to the piston 26. The oil pump 32 supplies a working oil 30 having a predetermined pressure to the piston 26 by driving a pump motor 33. When the pressure in the piston chamber 26d of the piston 26 rises and when the pressure is constant, the hydraulic oil 30 from the oil pump 32 flows through the orifice 36b because the orifice 36a is almost closed. It flows through chamber 26d and orifice 36a. In this state, the supply path 34 and the orifice 3
The pressure P1 at the connection point 34b of 6b and the pressure P2 at the connection point 34c between the check ring 37 and the piston chamber 26d are equal. The pilot pressure of the quick release valve 39 is also at these pressures P
Since 1 and P2 are equal, the rapid opening valve 39 is closed by the action of the preload spring 391.

Further, the control circuit 35 determines, based on a signal from a sensor for detecting the road surface condition, that the control circuit 35 should run at 4WD in which the degree of connection between the front and rear wheels is weak because the road surface condition is good. In this case, the value of the current supplied to the pump motor 33 is reduced. The pressure P1 of the check valve 37 on the oil pump 32 side decreases in accordance with the supplied current value.
Here, the pressure oil in the piston chamber 26d is supplied to the oil pump 3
The backflow prevention valve 37 is closed and prevented from flowing back to the second side. In this state, the pressure P2 of the piston chamber 26d is
Remain, the pressure P2 × the pressure receiving area S2> (pressure P1
× the pressure receiving area S1 + the load of the preload spring 391), and the quick release valve 39 is opened by the pressure difference between the pressure P2 and the pressure P1. . Thereby, the response at the time of pressure reduction can be hastened. The "pressure receiving area S1" refers to the area of the quick release valve 39 receiving the pressure P1 on the pump 32 side, and the "pressure receiving area S2" refers to the area of the quick release valve 39 receiving the pressure P2 on the piston chamber 26d side. Say. When the pressure P2 at the connection point 34c decreases and the pressure P2 × the pressure receiving area S2 <(the pressure P1 × the pressure receiving area S1 + the load of the preload spring 391), the quick release valve 39 closes again. here,
When the supply current to the pump motor 33 is maintained, the pressure P
1 is maintained, but the pressure oil in the piston chamber 26d continues to be discharged through the orifice 36a.
<Pressure P1. In this state, the check valve 37
Is opened again, and the pressure oil from the pump 32
d, the pressure P2 ≒ the pressure P1. In this manner, the pump motor 33 depends on the road surface condition.
When the current supplied to the piston chamber is increased or decreased, when the current decreases, the pressure in the piston chamber 26d can be quickly increased or decreased by opening the quick release valve 39. This quick release valve 39 has an effect of preventing a delay in pressure reduction when the viscosity of the hydraulic oil 30 increases in a low temperature state and the resistance when the hydraulic oil 30 passes through the orifice 36b increases.

On the other hand, an anti-lock brake system (A
In a vehicle equipped with BS), it is desired that the vehicle be in a 2WD state in which the front and rear wheels are not connected for proper operation of the ABS. Then, when the ABS is operated while traveling in the 4WD state, it is necessary to instantaneously switch to 2WD.
In this apparatus, the pump motor 3
3 cannot be stopped instantaneously due to the inertia of the pump motor 33, and even when the quick release valve 39 is operated, the piston chamber 26d is kept at a speed higher than the rate of reduction of the pressure P1 on the pump 32 side. The side pressure P2 cannot be reduced quickly. Here, when the supply current to the pump motor 33 is cut off at the same time as the operation of the ABS and the current is supplied to the forced open valve 40, for example, even if the pump motor 33 continues to rotate by inertia, the pump 32 side Since the pressure P1 can be instantaneously set to "0", the quick release valve 39 is opened, and the pressure oil in the piston chamber 26d can be instantaneously discharged and switched to 2WD. Here, the pressure P2 of the piston chamber 26d slightly remains due to the action of the preload spring 391 of the quick release valve 39, but there is no problem.

According to the first embodiment, since the hydraulic pressure supplied to the piston 26 is controlled by controlling the current supplied to the pump motor 33, it is possible to continuously control the clutch pressure. it can. In addition, expensive pressure control valves, pressure switches, relief valves,
Since an accumulator is not required, cost can be reduced. Further, since the number of parts can be reduced, the reliability is improved. Further, since only the pump motor 33 of the hydraulic oil supply mechanism 3 is attached to the outside of the case 2, the size of the entire device 1 can be reduced. Also,
When the pressure in the piston chamber 26d is lowered, the quick release valve 39 operates and the pressure oil in the pilot pressure circuit 39b on the oil pump 32 side is forcibly released by the forced release valve 40, so that the pressure is improved with good responsiveness. Descends. In particular, in a four-wheel drive vehicle equipped with an anti-lock brake system (ABS), the pressure reduction responsiveness at the time of operating the ABS poses a problem, but the present invention is also applicable. In this embodiment, the quick release valve 39 is a poppet valve, but may be a spool valve. Also, the forced release valve 40 may be a solenoid driven spool valve.

FIG. 4 shows a driving force distribution device according to a second embodiment of the present invention. In the second embodiment, the control circuit 35 controls the voltage applied to the pump motor 33.

FIG. 5 shows the relationship between the oil pressure P generated by the oil pump 32 and the voltage Vm applied to the pump motor 33. The oil pressure P generated by the oil pump 32 with respect to the voltage Vm applied to the pump motor 33 increases in proportion to the square of the voltage Vm. The relationship between the hydraulic pressure P and the voltage Vm is stored in a memory, and the hydraulic pressure supplied to the piston 26 can be controlled by controlling the voltage Vm applied to the pump motor 33 based on the stored contents of the memory. As in the first embodiment, the clutch pressure can be continuously controlled, and the number of parts can be reduced.

FIG. 6 shows a driving force distribution device according to a third embodiment of the present invention. This third embodiment is similar to the first embodiment.
In the hydraulic oil supply mechanism 3 of this embodiment, a temperature sensor 7 for detecting the temperature of the hydraulic oil 30 in the piston chamber 26d is provided, and the other configuration is the same as that of the first embodiment.

FIG. 7 shows the relationship between the oil pressure P generated by the oil pump 32 and the voltage Vm applied to the pump motor 33 using the temperature of the hydraulic oil 30 as a parameter. Oil pump 3
As shown in the figure, for example, the hydraulic pressure generated by 2 differs even at the same voltage Vm at normal temperature and at low temperature. Therefore, the control circuit 35 detects the operating oil 30 detected by the temperature sensor 7.
Of the oil pressure P and the voltage Vm stored in the memory based on the temperature of the
Is corrected, and the voltage Vm applied to the pump motor 33 is controlled based on the corrected contents, so that a desired clutch pressure can be obtained even if the temperature changes.

FIG. 8 shows a driving force distribution device according to a fourth embodiment of the present invention. This fourth embodiment is similar to the first embodiment.
In the hydraulic oil supply mechanism 3 of this embodiment, a pressure sensor 8 for detecting the pressure of the hydraulic oil 30 in the piston chamber 26d is provided, and the other configuration is the same as that of the first embodiment. According to the fourth embodiment, feedback control is performed based on the oil pressure detected by the pressure sensor 8 to control the current supplied to the pump motor 33, so that a highly accurate clutch pressure can be obtained.

In the above embodiment, the oil pump and the pump motor are provided in the case of the driving force distribution device. However, the oil pump and the pump motor may be provided in another place such as near the differential, and the case and the oil pump may be connected by a pipe. Good. In the second embodiment, similarly to the third embodiment, a temperature sensor is provided in the piston chamber 26d, and the characteristic curve shown in FIG. 5 is corrected according to the temperature of the hydraulic oil detected by the temperature sensor. May be used. In the second embodiment, similarly to the fourth embodiment, a pressure sensor is provided in the piston chamber 26d, and the voltage applied to the pump motor by feedback control based on the pressure of the hydraulic oil detected by the pressure sensor is determined. It may be controlled. Further, in the fourth embodiment, the pressure of the hydraulic oil in the piston chamber 26d is detected, but the discharge pressure of the oil pump may be detected. Also,
In the third embodiment, the temperature of the hydraulic oil in the piston chamber 26d is detected, but the temperature of the hydraulic oil supplied by the oil pump and the temperature of the hydraulic oil 30 stored in the lower portion 2a of the case 2 are detected. You may.

[0031]

As described above, according to the driving force distribution device of the present invention, since the hydraulic fluid from the pump is controlled by the control signal to the motor, the clutch pressure can be continuously controlled, and Costs can be reduced by reducing the number of points.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a driving force distribution device according to a first embodiment of the present invention.

FIG. 2A is a diagram illustrating a hydraulic circuit of a hydraulic oil supply mechanism according to a first embodiment, and FIG. 2B is a diagram illustrating blocks in the hydraulic circuit;

FIG. 3 is a diagram showing a relationship between a hydraulic pressure P generated by an oil pump and a current Im supplied to a pump motor.

FIG. 4 is a configuration diagram showing a driving force distribution device according to a second embodiment of the present invention.

FIG. 5 is a diagram showing a relationship between a hydraulic pressure P generated by an oil pump and a voltage Vm applied to a pump motor.

FIG. 6 is a configuration diagram showing a driving force distribution device according to a third embodiment of the present invention.

FIG. 7 is a diagram showing a relationship between a hydraulic pressure P generated by an oil pump and a voltage Vm applied to a pump motor using a temperature of hydraulic oil as a parameter.

FIG. 8 is a configuration diagram showing a driving force distribution device according to a fourth embodiment of the present invention.

FIG. 9 is a diagram showing a basic configuration of a four-wheel drive vehicle to which a conventional driving force distribution device is applied.

FIG. 10 is a configuration diagram of a conventional driving force distribution device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 drive power distribution device 2 case 2A device main body 2a lower part 3 hydraulic oil supply mechanism 5a pipe 5 hydraulic unit 6 control circuit 7 temperature sensor 8 pressure sensor 13 lever 14 piston 20A input shaft 20B rear wheel output shaft 20C front wheel output shaft 21A Ball bearing 21B Needle bearing 22C Chain 22A Drive sprocket 22B Driven sprocket 23 Multiple disc clutch 23a Clutch disc 23b Pusher plate 24 Clutch housing 24a Outer housing 24b Inner housing 25 Pressing member 26 Piston 26a Piston body 26b Cylinder 26c Packing 26d Piston chamber 27 Spring 28 Discharge path 30 Hydraulic oil 31 Strainer 32 Oil pump 33 Pump motor 34 Supply path 4a Supply port 34b, 34c Connection point 35 Control circuit 36a, 36b Orifice 37 Check valve 38 Filter 39 Piston pressure rapid release valve 39a, 39b Pilot pressure circuit 39c Discharge path 39d Discharge port 40 Forced release valve 41 Block 50 Oil pump 51 Pump Motor 52 Check valve 53 Accumulator 54 Pressure switch 55 Filter 56 Pressure control valve 57 Relief valve 58 Reservoir tank 101 Engine 102 Transmission 103 Center drive shaft 104 Differential 105 Rear wheel 106 Front drive shaft 107 Front wheel 391 Preload spring 400 Rod 401 Coil 402 Preload spring 410 block body

Claims (9)

[Claims] A driving force distribution device for transmitting a driving force from a prime mover to a front wheel and a rear wheel at a distribution ratio corresponding to the predetermined pressing force by pressing the multi-plate clutch with a predetermined pressing force by a pressing member. A piston that presses the multi-plate clutch via the pressing member; a pump that supplies a pressure fluid that generates a pressing force to press the pressing member to the piston to a piston chamber; A driving force distribution device, comprising: a motor for supplying the pressure fluid to a piston chamber; and control means for outputting a control signal corresponding to the distribution ratio to drive the motor. 2. The driving force distribution device according to claim 1, wherein said control means controls a supply current or an applied voltage to said motor. 3. The control device according to claim 2, wherein said control means includes a temperature sensor for detecting a temperature of said hydraulic fluid, and controls said supply current or said applied voltage based on a temperature of said hydraulic fluid.
The driving force distribution device according to the above. 4. The apparatus according to claim 2, wherein said control means includes a pressure sensor for detecting a pressure of said hydraulic fluid, and controls said supply current or said applied voltage based on a pressure of said hydraulic fluid.
The driving force distribution device according to any one of the preceding claims. 5. The driving force distribution device according to claim 1, wherein said piston chamber is provided with an orifice at an upper portion for discharging the supplied pressure fluid. 6. The driving force distribution device according to claim 1, wherein said piston chamber is provided with a supply port for supplying said pressurized liquid at an upper portion thereof. 7. The driving force distribution device according to claim 1, wherein said pump and said motor are provided in a case that houses said multi-plate clutch and said pressing member. 8. The driving force distribution device according to claim 1, wherein the case accommodating the multi-plate clutch and the pressing member has a liquid reservoir for storing the pressurized liquid below. 9. The control device according to claim 1, wherein said control means includes a hydraulic fluid discharge means for discharging said hydraulic fluid in a hydraulic fluid supply passage extending from said pump to said piston chamber when reducing the pressure in said piston chamber. The driving force distribution device according to claim 1.