JPS638025A - Four-wheel drive car - Google Patents

Abstract

PURPOSE:To eliminate a pump for exclusive use for controlling a clutch pressure, by a method wherein a valve is provided for controlling the pressure of delivery oil of an engine lubricating oil pump according to a running state, and the oil pressure is increased to feed it to the cylinder chamber of a multidisc clutch. CONSTITUTION:A part of delivery oil from a lubrication oil pump 50 is decreased in a pressure by means of a pressure reducing valve 54 to feed it in an oil pressure booster 53. Since, during straight running, the set pressure of a pressure reducing valve 54 is high, a pressure exerted on a piston 38 is increased, two clutch discs 42 and 43 are firmly engaged with each other. Meanwhile, during turning, the set pressure of the pressure reducing valve 54 is reduced with the increase in a steering angle signal, and an engaging force between the two clutch discs 42 and 43 is reduced. Since, as noted above, a clutch pressure can be controlled with the lubricating oil pump 50 serving as an oil pressure source, a pump for exclusive use for controlling a clutch pressure can be eliminated, and incurring of an energy loss can be decreased.

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.

<Prior Art> In a four-wheel drive vehicle configured such that two rotary shafts connected to the front wheel side and the rear wheel side are coupled so as to be relatively rotatable via a multi-disc clutch, control is provided to supply the multi-disc clutch. It is known that a dedicated pump is provided to generate pressure, and the pressure oil discharged from the pump is controlled to a pressure depending on the driving situation such as the steering angle.

<Problems to be Solved by the Invention> In the four-wheel drive vehicle having the above-mentioned configuration, there is a problem in that the cost is high because a dedicated voice is required.

<Means for Solving the Problems> The present invention has been made in view of the above-mentioned conventional problems, and its configuration is applicable to a four-wheel drive vehicle equipped with a multi-plate clutch between the front wheels and the rear wheels. , a pressure control valve that controls the pressure of lubricating oil discharged from a lubricating oil pump provided in the engine according to driving conditions such as a steering angle, and a booster that increases the pressure controlled by the pressure control valve. A supply passageway supplies the pressure increased by the booster to the cylinder chamber of the multi-disc clutch.

<Operation> With the above configuration, the pressure of the oil discharged from the engine lubricating oil pump is controlled according to the driving conditions such as the steering angle, and this pressure is increased and supplied to the cylinder chamber of the multi-disc clutch.
It can be controlled continuously between four-wheel drive and two-wheel drive depending on the driving situation.

<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 11. A differential case 14 of a front wheel side differential bag W13 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. A differential case 26 of a rear wheel III differential device 25 is rotatably connected to the propeller shaft 23, and a rear wheel 27.
A pair of left and right rear wheel shafts 29 and 30 to which the wheels 8 are attached are connected. 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 connected for relative rotation via a multi-disc clutch 35 having a configuration 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 fixed to 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 3
A transmission disk 41 is spline-engaged with one end of the transmission disk 2 facing the clutch case 37, and a plurality of clutch plates 42 are spline-engaged with the outer periphery of the transmission disk 41.

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. 45 is a pressure introduction port for supplying pressure oil to the cylinder chamber 39.

In FIG. 2, 50 indicates a lubricating oil pump built into the engine 10, and lubricating oil discharged from this pump 50 is supplied to each part of the engine via a supply passage 51. A control passage 52 branches off from the supply passage 51, and a hydraulic booster 53 is connected to one end of the control passage 52. A pressure reducing valve 54 of variable set pressure type is inserted in the control passage 52, and this pressure reducing valve 54 has a set pressure (secondary side pressure) that changes linearly in accordance with the current value applied to the solenoid SQL. It has become. Note that the control passage 52 is connected to the throttle valve 5 between the pressure reducing valve 54 and the hydraulic booster 53.
5 to an oil pan 56.

The hydraulic booster 53 has a large-diameter cylinder 61 connected to the control passage 52 and a small-diameter cylinder 62 connected thereto, and a large-diameter piston 63 and a small-diameter piston 64 are slidable in these cylinders 61 and 62, respectively. fitted,
Both pistons 63 and 64 are connected to each other by a connecting rod 65. The small diameter cylinder 62 is connected to the pressure inlet 45 of the multi-disc clutch 35 via a communication passage 67. Also, a check valve 68 is installed in the small diameter cylinder 62.
A reservoir 69 is connected via the.

The small-diameter cylinder 62, the communication passage 67, and the cylinder chamber 39 of the multi-disc clutch 35 constitute a closed circuit, and this closed circuit is filled with oil for pressure medium. Note that 70 is a relief valve that sets the upper limit of the discharge pressure of the lubricating oil pump 50.

Reference numeral 71 indicates a control circuit including a microcomputer that controls the current value to be applied to the solenoid SQL of the pressure reducing valve 54, and this control circuit 71 is connected to a steering angle signal detected by a steering angle sensor (not shown). θ is input, a current value corresponding to the steering angle signal θ is supplied to the solenoid of the pressure reducing valve 54, and the secondary pressure of the pressure reducing valve 54 is controlled as shown in FIG.

In the above configuration, the lubricating oil discharged from the lubricating oil pump 50 is supplied to each part of the engine through the supply passage 51, and is reduced in pressure by the pressure reducing valve 54 in the control passage 52, and is then supplied into the hydraulic booster 53. When traveling straight ahead with a small steering angle, the set pressure of the pressure reducing valve 54 is high, and this pressure increases the pressure medium oil in the closed circuit by the hydraulic booster 53, so the pressure acting on the piston 38 is increased. As a result, both clutch plates 42 and 43 of the multi-disc clutch 35 are firmly connected, and the front wheels and the rear wheels are almost directly connected to maintain a four-wheel drive condition.

On the other hand, when the car is turning, the set pressure of the pressure reducing valve 54 is reduced as shown by the dotted line in FIG. The multi-plate clutch 35 is lowered as shown by the solid line in the figure.
The joining force between the clutch plates 42 and 43 is weakened, allowing the clutch plates 42 and 43 to slip against each other. This avoids tight corner braking phenomena when the car turns.

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 it is of course possible to control the clutch pressure according to other driving conditions such as the vehicle speed or the state of slippage with the road surface. .

<Effects of the Invention> As described above, the present invention provides an engine'/R? Since the clutch pressure is controlled using the lubricating oil pump as a hydraulic source, a dedicated pump for clutch pressure control is not required, and the pressure is controlled within the range of the lubricating oil pump's discharge pressure. Therefore, compared to a system using a dedicated pump, energy loss can be reduced and other effects 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 pressure control of a pressure reducing valve. It is a line diagram showing characteristics. 15.16...Front wheel, 27.28...Rear wheel, 35.
...Multi-plate clutch, 39...Cylinder chamber, 50...
Lubricating oil pump, 54...pressure control valve (pressure reducing valve).

Claims (1)

[Claims] (1) In a four-wheel drive vehicle equipped with a multi-disc clutch between the front wheels and rear wheels, the pressure of lubricating oil discharged from the lubricating oil pump installed in the engine is controlled according to the driving conditions such as the steering angle. A pressure control valve that increases the pressure controlled by the pressure control valve, a booster that increases the pressure controlled by the pressure control valve, and a supply passage that supplies the pressure increased by the booster to the cylinder chamber of the multi-disc clutch. 4 wheel drive vehicle.