JPH0412802Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a control device for a hydraulic vehicle height adjustment device for an automobile.

Prior Art A wheel suspension system is equipped with a vehicle height adjustment device using a hydraulic cylinder device, and by supplying oil to the hydraulic cylinder device, a high vehicle height is achieved, and by discharging oil from the hydraulic cylinder device, a low vehicle height (normal vehicle height) is achieved. Vehicle height)
In a vehicle equipped with a hydraulic vehicle height adjustment device, when the oil pump operates to supply oil to the hydraulic cylinder device to raise the vehicle height, when the hydraulic cylinder device reaches its operating limit position, the oil supply system Focusing on the sudden increase in the oil pressure of the vehicle, the present applicant has developed an oil pressure switch that detects the rapidly increasing oil pressure value as a vehicle height sensor and stops the operation of the oil pump. , and has already applied for utility model registration as Utility Model Application No. 158998/1983 (see Japanese Utility Model Application No. 60/66513).

In the above prior art, as shown in FIG. The oil in the tank 100 is checked by the check valve 4.
00, and is supplied from the check valve 500 through the oil passage a and the pipe b into the hydraulic cylinder device for adjusting the vehicle height of each wheel suspension system, thereby increasing the vehicle height, and the oil pump When the oil 200 rotates in the opposite direction, the oil is sucked up through the check valve 600 in the oil tank 100, and is supplied to the end face of the valve body 301 of the control valve 300 through the oil passage c. More oil tank 100
The oil pressure flows into the valve body 3 of the control valve 300.
01 operates against the spring 302 and passes through the drain oil passages e and f, and the oil in each vehicle height adjustment hydraulic cylinder device passes from the pipe b through the drain oil passages e and f. It flows into the pump 100 to lower the vehicle height, and when raising the vehicle height, after each vehicle height adjustment hydraulic cylinder device extends and hits the upper limit stopper, the hydraulic pressure in the hydraulic pressure supply path is reduced to the first level. Taking advantage of the sudden increase in oil pressure from P ₁ in Figure 5, the oil pressure switch 700 installed in the oil passage a detects the sudden increase in the oil pressure value P ₂ and operates the oil pump 200 based on the detection signal. It was designed to stop it.

Problems to be solved by the invention In the hydraulic vehicle height adjustment device as described above,
When lowering the vehicle height from a high vehicle height to a low vehicle height (normal vehicle height), it is desirable to use an oil pressure switch as a vehicle height sensor, just as when raising the vehicle height above. It is extremely difficult to detect the lowering limit position of the vehicle height and stop the reverse rotation of the oil pump.

In other words, in general, it is technically almost impossible to set the operating pressure of an oil pressure switch to a pressure point that is zero or close to zero, and the piston in the hydraulic cylinder device is not in the cylinder at the lowering limit position of the vehicle height. It is difficult for the oil pressure switch to detect when the oil pressure reaches zero due to contact with the stopper.

Means for Solving the Problems The present invention is a vehicle height sensor that detects the lowering limit position of the vehicle height. In addition to using an oil pressure switch whose operating setting pressure is a hydraulic pressure value close to the lower limit that can be detected with a general oil pressure switch, for example, about 5 Kgf/ ^cm2 , the operation of the oil pressure switch is The present invention is characterized in that a delay circuit is provided, which causes the oil pump to continue rotating in reverse for a predetermined period of time after the signal is issued, and then stops the operation of the oil pump.

Effect In the above, the setting time of the delay circuit is set to a time that is equal to or slightly longer than the time required for the oil pressure to go from the oil pressure at the time when the oil pressure switch issues the activation signal to zero oil pressure. By doing so, the oil pump continues to operate until the oil pressure in the oil spill system becomes zero after the vehicle height reaches the lowering limit position, and then automatically stops.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

In FIG. 1, 1 is a power source, 2 is an ignition switch, and 3 is a vehicle height control switch, and the ON and OFF signals of the vehicle height control switch 3 are input to a control circuit 4. .

Reference numeral 5 designates a motor for driving an oil pump (corresponding to the oil pump 200 shown in FIG. 4), which is not shown. The motor 5 rotates forward or reverse depending on the operation of the vehicle height up relay 6 or the vehicle height down relay 7. It's supposed to rotate.

Reference numeral 8 designates an oil pressure switch (referred to as oil pressure switch HI) for detecting the vehicle height raising limit position, and indicates that the oil pressure in the oil supply system to the vehicle height adjustment hydraulic cylinder device (not shown) is below a set value. It turns on when the value exceeds the set value, and turns off when the value exceeds the set value.

9 is an oil pressure switch (referred to as oil pressure switch LO) for detecting the lowering limit position of the vehicle height, and is turned on when the oil pressure in the oil outflow system in the hydraulic cylinder device is above a set value. It turns off when the value falls below a set value.

The oil pressure switch HI8 and the oil pressure switch LO9 are, for example, similar to the oil pressure switch 700 shown in FIG.
installed in oil passages such as

Reference numeral 10 indicates a delay circuit, and the OFF signal of the oil pressure switch LO9 is input to the control circuit 4 after a predetermined time delay.

11 is a speed sensor, and 12 is an indicator lamp.

In the above case, in the normal vehicle height (low vehicle height) state with the vehicle height control switch 3 turned off, the oil pressure switch HI8 is on and the oil pressure switch LO9 is off.

When the vehicle height control switch 3 is turned on from this state, the control circuit 4 generates an output to turn on the up relay 6 based on the on signal, and the relay 6 is turned on, causing the motor 5 to rotate in the forward direction. The pump rotates forward to pump oil into a hydraulic cylinder device (not shown) installed in the wheel suspension system, raising the vehicle height.

The change in oil pressure in the oil passage when raising the vehicle height from a low vehicle height to a high vehicle height is as shown in Figure 5. When the oil pressure increases from zero to P ₁ , the hydraulic cylinder device starts to rise and the oil pressure increases. When the piston of the cylinder device reaches the upper limit position and hits the upper limit stopper, the oil pressure in the oil supply passage increases rapidly, exceeding the set pressure _P2 of the oil pressure switch HI8, and turning off the oil pressure switch HI8. In response to the signal, the control circuit 4 turns off the up relay 6, stops the motor 5, and the vehicle height becomes high.

At the beginning of this vehicle height raising operation, the oil pressure switch LO9 is turned on.

When the vehicle height control switch 3 is turned off in this high vehicle height state, the control circuit 4
generates an output and turns on the down relay 7, causing the motor 5 to rotate in the reverse direction and causing the oil pump to rotate in the reverse direction.

Then, the control valve (not shown) (the control valve shown in FIG. 4) is activated by the discharge hydraulic pressure caused by the reverse rotation of the oil pump.
(corresponding to 300) is operated to open the oil outflow path to drain the oil in the hydraulic cylinder device to the oil tank.

Then, the oil pressure in the oil outflow path becomes as shown in Figure 2.
After descending from P ₂ to P ₁ , the vehicle height is lowered while maintaining the oil pressure P ₁ , and from the moment the piston of the hydraulic cylinder device reaches the lower limit position, the oil pressure decreases from P ₁ to zero at a certain slope. However, as mentioned above, it is technically impossible for a normal oil pressure switch to set an oil pressure of 0 Kgf/cm ² or an oil pressure value close to it as an operating setting value.

Therefore, in this invention, the oil pressure value P ₀ during the lowering of the oil pressure after the moment when the piston reaches the lower limit position (an oil pressure value near the lower limit of the oil pressure value range that can be detected by a general oil pressure switch, for example, 5 kgf/cm ² )
Set as the off operating point of oil pressure switch LO9.

Therefore, oil pressure switch LO9 is turned off before the operation of lowering the vehicle height from high to normal is completed.
The off signal is not input to the control circuit 4 by the delay circuit 10 at that time, the motor 5 and the oil pump continue to rotate in reverse, and the oil in the hydraulic cylinder device continues to flow out.

By setting the delay setting time of the delay circuit 10 to the time T from when the oil pressure switch LO9 is turned off until the oil pressure in the oil spill path becomes zero, the vehicle height is set to the normal vehicle height. When the switching operation is completely completed, an off signal from the oil pressure switch LO9 is input to the control circuit, the down relay 7 is turned off, and the reverse rotation of the motor 5 and oil pump is stopped.

At the beginning of this operation to lower the vehicle height, the oil pressure switch HI8 is turned on,
Prepare for the next vehicle height raising operation.

The time it takes for the oil pressure to drop from P ₁ to zero when the vehicle height is lowered as described above varies depending on the elasticity and length of the hydraulic piping, the elasticity of the lower limit stopper that regulates the lowering limit position of the piston, etc. In addition, it also depends on the viscosity of the oil. That is, assuming that the elasticity and length of the hydraulic piping and the elasticity of the lower limit stopper of the piston are constant, the time from when the oil pressure switch LO9 is turned off to when the oil pressure becomes zero is as shown in Figure 3. It goes without saying that when the viscosity of the oil is low, it is short like T ₁ , and when the viscosity is high it becomes long like T _2. Also, the viscosity of the oil varies not only with the type of oil but also with changes in the outside temperature. It also changes with changes in temperature.

Therefore, the delay setting time of the delay circuit 10 is set using a highly viscous type of oil when the outside temperature is extremely low (for example, -30°C).
By setting the time from when oil pressure switch LO9 is turned off until the oil pressure reaches zero (approximately 5 seconds in experiments) when the vehicle height is lowered (approximately 5 seconds in experiments), the vehicle height lowering operation can be stopped midway. The down operation can always be made to stop after the vehicle has been completely lowered to the normal vehicle height. In this case, if the viscosity of the oil is low, the oil pump will continue to rotate in reverse and keep the oil outflow path open for several seconds even after the oil pressure in the oil outflow path reaches zero, but there is no functional problem at all.

As shown in FIG. 1, a speed sensor 11 is used and the vehicle height is lowered from high to normal when driving at high speed based on the signal from the speed sensor 11 in order to improve high speed driving stability. The completion of the vehicle height lowering operation by the sensor 11 is completed using the oil pressure switch LO9 as described above.
and the delay circuit 10, the control circuit 4 can accurately detect the vehicle height and set the vehicle height to a completely normal vehicle height.

Effects of the invention As described above, according to the present invention, by using extremely simple measures, the oil pressure switch can be used not only as a vehicle height sensor when the vehicle height is raised, but also as a vehicle height sensor when the vehicle height is lowered. The structure of the hydraulic vehicle height adjustment device can be significantly simplified and costs can be reduced, and together with improved functionality, this can bring about great practical effects.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an embodiment of the present invention, and Fig. 2 shows changes in the oil pressure in the oil spill system when the vehicle height is lowered and the operating setting pressure of the oil pressure switch for detecting the vehicle height lowering limit position. FIG. 3 is a diagram illustrating the difference in the change in oil pressure in the oil spill system when the vehicle height is lowered due to the difference in oil viscosity. FIG. 4 is an explanatory diagram showing an example of a conventional vehicle height control oil pump device, and FIG. 5 is a diagram showing changes in oil pressure when the vehicle height is increased in the device shown in FIG. 1...Power supply, 3...Vehicle height control switch, 4...
Control circuit, 5...Motor, 6,7...Relay,
8, 9...Oil pressure switch.

Claims (1)

[Scope of utility model registration request] A vehicle height adjustment device consisting of a hydraulic cylinder device is provided in the wheel suspension device, and oil is supplied to the hydraulic cylinder device by forward rotation of an oil pump to raise the vehicle height.
In automobiles that lower the vehicle height by draining the oil in the hydraulic cylinder device by reverse rotation of the oil pump, the vehicle height sensor is used to detect the lower limit position of the vehicle height. An oil pressure switch is used whose operation setting pressure is set to a predetermined oil pressure value during a decrease in oil pressure in the oil spill system that drains oil, and the oil pump is operated for a predetermined period of time after the activation signal of the oil pressure switch is issued. 1. A control device for a hydraulic vehicle height adjustment device for an automobile, characterized in that a delay circuit is provided for stopping the oil pump after continuing the reverse rotation operation of the oil pump.