JPS6311425A - Four-wheel drive automobile - Google Patents

Abstract

PURPOSE:To prevent the braking phenomenon at tight corner by supplying a pressure into the cylinder chamber of a multidisc clutch when a car turns and allowing the slip of the clutch plate by weakening the connection force between the clutch plates by a spring. CONSTITUTION:The pressurized oil supplied from a pump 50 for power steering is allowed to diverge to a power steering device 56 side and a multidisc clutch 33 side by a divergence flow control valve 51. When a car turns, the throttle area of a variable throttle 61 is contracted by increasing the electric current value supplied into an electromagnetic throttle valve 60 according to the increase of the steering angle signal theta input into a controller 65. The pressure introduced into a cylinder chamber 39 is increased by increasing the resistance drained through the variable throttle 61. Therefore, a piston 38 is operated so that the pressing force due to a spring 45 is lightened, and the connection force between the clutch plates 42 and 43 is weakened. Therefore the braking phenomenon at tight corner can be prevented, when the car turns.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a four-wheel drive vehicle in which front wheels and rear wheels can be rotationally connected via a multi-plate clutch.

<Conventional Technology> In a four-wheel drive vehicle that has two rotating shafts connected to the front and rear wheels that are relatively rotatably connected via a multi-disc clutch, high pressure is applied to the multi-disc clutch when driving straight. It is necessary to supply pressure to control the vehicle into a four-wheel drive state, and to control the vehicle to a two-wheel drive state by reducing the pressure supplied to the multi-disc clutch in order to avoid the braking phenomenon at tight corners when cornering.

<Problems to be Solved by the Invention> In the above-mentioned four-wheel drive control, in which the oil discharged from the pump is controlled by a solenoid valve in order to control the clutch pressure, it is necessary to control the drive torque as a full-time four-wheel drive. To transmit most of the time the pump pressure is 10 kg/
It is necessary to maintain a high pressure of CT1 or higher, and therefore there is a problem of large energy loss.

<Means for Solving the Problems> The present invention has been made in view of the above-mentioned conventional problems. , the multi-disc clutch includes clutch plates that can be engaged with each other for transmitting driving torque between front wheels and rear wheels, a slidable piston that controls the engagement force of the clutch plates, and a movable piston that is connected to the piston. It consists of a spring that presses the clutch plates in the direction in which they come into contact with each other, and a cylinder chamber that is formed on the side opposite to this spring and reduces the pressing force by the spring according to the supply pressure. A pressure supply means for supplying pressure is provided.

<Operation> With the above configuration, the clutch plates are normally connected by the springs and the four-wheel drive state is maintained.

When the vehicle turns, pressure is supplied to the cylinder chamber, and the force applied to the clutch plates by the spring is reduced in accordance with this supplied pressure, allowing the clutch plates to slip. Therefore, tight corner braking phenomena when turning are avoided.

<Example> Embodiments of the present invention will be described below based on the drawings.

In FIG. 1, 10 indicates an engine, and the output of this engine 10 is transmitted to a drive shaft 12 via a transmission 1). A differential case 14 of a front wheel differential device 13 is rotatably connected to the drive shaft 12.
A pair of left and right front wheel shafts 17.degree. 18 having front wheels 15, 16 mounted thereon are connected to this differential device 13. As a result, the driving torque from the drive shaft 12 is divided by the differential device 13 and transmitted to the left and right front wheel shafts 17.18, thereby rotationally driving the left and right front wheels 15.16.

A rear export force shaft 21 is also rotatably connected to the drive shaft 12, and a propeller shaft 23 is connected to the rear export force shaft 21 via a bevel gear 22. The propeller shaft 23 has a differential case 26 of the rear wheel differential device 25.
A pair of left and right rear wheel shafts 29,30 having rear wheels 27,28 attached thereto are connected to this differential device 25. As a result, the driving torque transmitted from the drive shaft 12 to the propeller shaft 23 is divided by the differential device 25 and transmitted to the left and right rear wheel shafts 29.30, thereby rotationally driving the left and right rear wheels 27.28. .

The propeller shaft 23 has a first shaft connected to the front wheel side.
It is composed of a rotating shaft 31 and a second rotating shaft 32 connected to the rear wheel side, and these first and second rotating shafts 31, 32
are relatively rotatably connected via a multi-plate clutch 35 having a configuration to be described later.

FIG. 2 shows the configuration of the multi-disc clutch 35, in which the first rotating shaft 31 and the second rotating shaft 32 are rotatably supported on the same axis by a fixed case 36. A clutch case 37 is formed at one end of the first rotating shaft 31, and a cylinder chamber 39 in which a piston 38 is slidably fitted is formed in the clutch case 37. On the other hand, the second rotating shaft 32
A connecting disk 41 is spline-engaged with one end of the clutch case 37 so as to face the clutch case 37, and a plurality of clutch plates 42 are spline-engaged with the outer periphery of the connecting disk 41. Further, a plurality of clutch plates 43 are spline-engaged with the inner periphery of the clutch case 37, and these clutch plates 42.
43 are alternately arranged so as to be able to approach and separate from each other. A spring 45 is provided between the cylinder chamber 39 and the piston 38.
is inserted, and the force of this spring 45 constantly presses both the clutch plates 42 and 43 in the direction in which they are brought into contact. The spring 45 is, for example, set as a spring T@ which can transmit about 50% of the output torque of the engine 10 from the front wheel side to the rear wheel side.

A pressure introduction port 47 is opened in the cylinder chamber 39 on the side opposite to the spring 45 .
) In FIG. 2, 50 indicates a power steering pump driven by the engine 10, and the discharge amount of this pump 50 is controlled to a constant flow rate by a flow control valve built into the pump. pump 50-6
One discharge flow rate is controlled by the branch control valve 51 between two outlet ports I and I.
53 and 54 at a constant flow rate.

The one outlet port 53 is connected to the supply port of a known power steering device 56 via a passage 55, and the other outlet port 54 is connected to the pressure inlet 47 of the multi-disc clutch 35 via a passage 57. It is connected.

A passage 57 communicating with the cylinder chamber 39 of the multi-disc clutch 35 has a variable throttle 61 that is variably controlled by an electromagnetic throttle valve 60.
The hydraulic pressure introduced into the cylinder chamber 39 of the multi-disc clutch 35 is controlled according to the throttle area of the variable throttle 61.

Further, 65 indicates a control circuit 66 made of a microcomputer that controls the current value io to be applied to the solenoid of the electromagnetic throttle valve 60, and this control circuit 66 is connected to a steering angle signal detected by a steering angle sensor in the enclosure. θ is input, and the current value 1o is set according to the steering angle signal θ as shown in FIG. When making a large turn, the current value to be applied is controlled to be high.

Further, as shown in FIG. 4, the variable throttle 61 of the electromagnetic throttle valve 60 has a throttle area A that is linearly changed according to the applied current value 10, and when the current value 10 is O, the throttle area A
is held at a maximum, and when the current value io is at a maximum, the aperture area A is held at a minimum.

In the above configuration, a constant flow rate of pressure oil discharged from the power steering pump 50 is divided into the power steering device 56 side and the multi-disc clutch 33 side at a constant flow rate by the flow control valve 51. In normal times when the car is traveling almost straight, the current value i supplied to the solenoid of the electromagnetic throttle valve 60 is
o is low and therefore the throttle area A of the variable throttle valve 61 is large, the constant flow of pressure oil diverted to the multi-disc clutch 33 side is drained through the variable throttle valve 61 of the electromagnetic throttle valve 60 with almost no resistance. As a result, the pressure supplied to the cylinder chamber 39 via the pressure introduction port 47 is maintained at a low pressure.

Therefore, both clutch plates 42 and 43 of the multi-disc clutch 33 are firmly connected by the spring 45, and the front wheels and rear wheels are almost directly connected to maintain a four-wheel drive condition.

On the other hand, when the car is turning, the current value to supplied to the solenoid of the electromagnetic throttle valve 60 increases as the steering angle signal θ increases, so that the throttle area A of the variable throttle valve 61 increases.
is reduced, thereby increasing the resistance drained through the variable throttle 61, and the pressure introduced into the cylinder chamber 39 increases as shown by the dotted line in FIG. The pressure exerted on the piston 38 by the spring 45 acts to reduce the force, so that the clutch plates 42.
As shown by the solid line in FIG. 5, the connecting force of the clutch plates 42 and 43 is weakened in proportion to the increase in the steering angle signal θ, allowing the clutch plates 42 and 43 to slip against each other. This avoids braking phenomena in tight corners when the car turns.

In the above-described embodiment, an example was described in which a power steering pump was used to control the pressure of a multi-disc clutch, but the present invention also applies to a system in which a dedicated pump is used to control the pressure of a multi-disc clutch. Of course, it is applicable.

Furthermore, in the above embodiment, an example was described in which the pressure of the multi-disc clutch is controlled according to the steering angle, but the clutch pressure can also be controlled according to other driving conditions such as the vehicle speed or the state of slippage with the road surface. It is something.

<Effects of the Invention> As described above, the present invention normally uses a spring force to connect the clutch plates of a multi-disc clutch with maximum engagement force to maintain the four-wheel drive state, and when the car turns, the clutch plates of the multi-disc clutch are engaged by the spring. Since the structure is such that hydraulic pressure is applied to the piston in the direction of reducing the force, the time when the pump is at high pressure can be reduced even in full-time four-wheel drive, and the effect of reducing energy loss can be achieved.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; Fig. 1 is a schematic diagram showing a four-wheel drive vehicle, Fig. 2 is a hydraulic system diagram for controlling a multi-disc clutch, and Fig. 3 is a line showing current characteristics. 4 is a diagram showing throttle control characteristics of the electromagnetic throttle valve, and FIG. 5 is a diagram showing clutch control characteristics. 15.16...Front wheel, 27.28...Rear wheel, 35.
...Multi-plate clutch, 38... Piston, 39... Cylinder chamber, 42.43... Clutch plate, 45... Splinter-50... Pump, 60... Electromagnetic throttle valve.

Claims (2)

[Claims] (1) In a four-wheel drive vehicle equipped with a multi-disc clutch between front wheels and rear wheels, the multi-disc clutch includes clutch plates that can be connected to each other and that transmit driving torque between the front wheels and the rear wheels; A slidable piston for controlling the joining force of the clutch plates, a spring for pressing the piston in the direction in which the clutch plates are brought into contact with each other, and a spring for pressing the piston in the direction in which the clutch plates are brought into contact with each other; Consists of a cylinder chamber that reduces the pressing force caused by the spring,
A four-wheel drive vehicle is provided with a pressure supply means for supplying pressure to the cylinder chamber when the vehicle turns. (2) The pressure supply means is constituted by a pump and a solenoid valve that controls the oil discharged from the pump to a pressure according to the driving condition such as the steering angle. wheel drive car.