JPH0419211A - Hydraulic system control method - Google Patents

Abstract

PURPOSE:To prevent the generation of impact noise at the operation stop time in an active suspension device by inputting an electric signal corresponding to the cylinder pressure before releasing electric signals to a solenoid proportional relief valve so as to maintain a control valve in the setting work state. CONSTITUTION:With an ignition switch turned off, the cylinder pressure of a hydraulic cylinder 2 is detected by a sensor 1 and inputted into a controller. The controller outputs a signal proportional to this cylinder pressure to a control valve 4 so as to control the cylinder pressure of the hydraulic cylinder 2 to be the pressure at the resting time of a hydraulic system, that is, to maintain the expansion state of the hydraulic cylinder 2. The controller then releases specified signals to a solenoid proportional relief valve 8a gradually. With this constitution, the generation of valve impact noise can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of controlling a hydraulic system that is optimal for use in a hydraulic system such as an active suspension system as a suspension system of a vehicle.

(Prior art and its problems) There have been various proposals for hydraulic systems such as active suspension systems used as vehicle suspension systems. We have developed a hydraulic system that is a suspension system.

However, is it common to this type of hydraulic system?
Even with the hydraulic system developed for the above-mentioned optical system, noise may be generated depending on the control method.

That is, the hydraulic system developed above, like the previous one, is a single-acting cover placed between the suspension arm A, which is the axle of the vehicle, and the vehicle body B, with the suspension spring 1, which is the energizing spring, interposed. The hydraulic cylinder 2 has a hydraulic cylinder 2, and the cylinder pressure in the hydraulic cylinder 2 is increased by supplying hydraulic pressure from a hydraulic source 3 to an oil chamber 2a in the hydraulic cylinder 2 via a control valve 4, and By discharging the hydraulic pressure from the oil chamber 2a to the tank 5 via the control valve 4,
Decreasing the cylinder pressure in the hydraulic cylinder 2,
It is formed so that the height of the vehicle can be adjusted.

Incidentally, the control valve 4 is operated by a command signal, that is, an electric signal, from a controller (not shown).

The hydraulic system includes a communication path 8 disposed between a supply path 6 that communicates the hydraulic pressure #i3 and the control valve 4, and a discharge path 7 that communicates the tank 5 and the control valve 4. An operated check valve 7a is provided in the discharge passage 7 to prevent hydraulic pressure from being discharged from the control valve 4 side to the tank 5 side.
A switching valve 9a serving as an on/off valve is provided in a communication passage 9 that communicates one of the control valves 4 located at the upper side in the figure with the discharge passage 7.

Also, the electromagnetic proportional relief valve 8a is.

The operating check valve 7a is operated by a command signal from the controller, and is in an open valve state when pilot pressure is supplied through the pilot passage 6a communicating with the -F supply path 6, and the above-mentioned switching The valve 9a is formed to be in the communicating position when pilot pressure is supplied through the pilot passage 6a.

The hydraulic system L has an accumulator 6b in the supply path 6 between the hydraulic source 3 and the control valve 4, and a check valve 6 in the supply path 6 between the accumulator 6b and the control valve 4.
A pressure sensor SI and a throttle 2c are installed in each oil passage 2b that communicates each hydraulic cylinder 2 and each control valve 4.
and a gas spring 2d via the throttle 2c,
Furthermore, the vehicle body B includes a vehicle sensor S2.

The L accumulator 6b accumulates a predetermined hydraulic pressure on the so-called supply side, and the check valve 6C prevents the hydraulic pressure from flowing back from the control valve 4 side to the hydraulic pressure sensor 3 side.
detects the cylinder pressure in each hydraulic cylinder 2, the throttle 2c functions as a damping valve, the Cas spring 2d functions as a gas spring, and the vehicle sensor S2 detects the state of the vehicle.

Further, each detection signal from the L pressure distribution sensor S1 and the vehicle sensor S2 is input to the controller.

Therefore, in the hydraulic system developed above, the signals from the pressure sensor S1 and the pressure sensor s2 are input to the controller, and the electric signals from the controller are used to input the signals from the hydraulic source 3, control valve 4, and Electromagnetic proportional relief valve 8a
or each will be driven.

When the control valve 4 is driven, the oil pressure in the oil chamber 2a of the hydraulic cylinder 2, that is, the cylinder pressure, is adjusted in height, and the height of the vehicle is adjusted.

As a result, since the hydraulic cylinders 2 are arranged at each of the four wheels of the vehicle, by adjusting the cylinder pressure in each hydraulic cylinder 2, the vehicle body posture can be appropriately controlled depending on the road surface conditions on which the vehicle is traveling. become.

However, even in the hydraulic system developed above, the suspension of operation is realized by the so-called off operation of an ignition switch (not shown), or the supply path 6 and The electromagnetic proportional relief valve 8a disposed in the communication passage 8 that communicates with the discharge passage 7 enters the so-called OFF state, and as a result, the oil pressure in the supply passage 6 suddenly decreases, and of course the electromagnetic proportional relief valve 8a In particular, the operating check valve 7a disposed in the discharge passage 7
The switching valve 9a disposed in the communication passage 9 will be switched at high speed, and at this time, so-called noise, which is a valve impact sound, will be generated in the valves 8a, 7a, and 9a, respectively.

When this noise, which is the valve impact sound, occurs, an impulsive operating state occurs in each of the valves 8a, 7a, and 9a, and therefore, the hydraulic system is repeatedly stopped and the valves 8a, 7a, and 9a are in an impulsive operating state. There is also an inconvenience that failure may occur due to breakage of members of the hydraulic system 9a itself, resulting in malfunction or inoperability of the hydraulic system.

This invention was devised in view of the above-mentioned circumstances, and its purpose is to prevent the production of so-called valve impact noise when the suspension system of a vehicle is suspended. An object of the present invention is to provide a control method for a hydraulic system that is optimal for use in hydraulic systems such as suspension systems.

(Means for Solving the Problems) In order to achieve the above object, the configuration of the present invention is such that the cylinder pressure in the hydraulic cylinder is increased by supplying hydraulic pressure from a hydraulic source to the oil chamber of the hydraulic cylinder via a control valve. A supply path that is formed to lower the cylinder pressure in the hydraulic cylinder by raising the hydraulic pressure from the oil chamber or discharging the hydraulic pressure from the oil chamber to the tank via the control valve, and communicating the hydraulic pressure source and the control valve. and a discharge passage that communicates between the tank and the control valve, and an electromagnetic proportional relief valve that sets the oil pressure in the supply passage in the communication passage arranged between the tank and the control valve, and operates using the oil pressure in the supply passage as pilot pressure. The discharge passage has an operated check valve that allows hydraulic pressure from the control valve side to be discharged to the tank side, and the hydraulic pressure in the supply passage is operated as pilot pressure to discharge the hydraulic pressure from the control valve side to the tank side. A hydraulic system configured to release an electric signal to the control valve and the electromagnetic proportional relief valve when the hydraulic system is configured to have a switching valve in a communication path that communicates the control valve and the discharge path. In the system control method, before releasing the electric signal to the electromagnetic proportional relief valve, an electric signal corresponding to the cylinder pressure in the hydraulic cylinder is inputted to the control valve so that the control valve is maintained in a set operating state. After that, the electric signal to the electromagnetic proportional relief valve is gradually canceled, and then the electric signal to the control valve is canceled.

[For production]

Therefore, when the ignition switch is turned off in order to check the operation of the hydraulic system, the cylinder pressure in the hydraulic cylinder at this time is detected by the pressure sensor, and the detected value is input to the controller. The controller outputs a command signal, ie, an electric signal, corresponding to the cylinder pressure to the control valve.

As a result, the cylinder pressure in the hydraulic cylinder is maintained at the value when the hydraulic system is inactive, that is, at the extended or contracted state of the hydraulic pressure of 8 when the hydraulic system is inactive.

Thereafter, the controller gradually releases the electrical signal to the electromagnetic proportional relief valve.

As a result, the oil pressure in the supply path is gradually lowered.

Thereafter, the electric signal to the control valve is canceled by a command from the controller.

By the above-described operation, the oil pressure on the supply path side of the hydraulic system is gradually lowered, and therefore, a sudden oil pressure drop on the supply path side is not caused.

At this time, either the control valve goes to the discharge position and allows the pressure oil from the hydraulic cylinder to be discharged to the tank side, or the pilot valve to the operating check valve installed in the discharge path Since the pressure is released, the operating check valve functions as a so-called check valve, thus preventing the discharge of pressure oil from the hydraulic cylinder, resulting in a decrease in the cylinder pressure in the hydraulic cylinder, i.e.
This will result in a reduction in the height of the vehicle.

And after that, by turning off the power to the controller,
The operation of the hydraulic system can be completely stopped.

〔Example〕

Hereinafter, the present invention will be described in detail based on the illustrated embodiments.

It should be noted that the active suspension system shown in FIG. 2, which was previously developed by the applicant of the present application, is suitable as the hydraulic system to be used in carrying out the present invention. Therefore, the explanation thereof will be omitted and only the reference numerals will be used, and the method for controlling the hydraulic system according to the present invention will be explained below through explanation of the operation of the active suspension system.

First, the method for controlling the active suspension system, which is a hydraulic system according to the present invention, is divided into a first stage and a second stage, as shown in FIG.

To explain briefly, in the first step, when starting the operation of the system, the ignition switch is first turned on (see reference numeral II in the figure).

As a result, the cylinder pressure in the hydraulic cylinder 2 is detected by the pressure sensor S1, and the detected value is input to a controller (not shown) (see reference numeral 12 in the figure) 6. Then, the controller outputs a signal corresponding to the cylinder pressure. A command signal, ie, an electric signal, is output to the control valve 4 (see reference numeral 13 in the figure).

In addition, a predetermined electric signal is output from the F controller to the electromagnetic proportional relief valve 8a (numeral 148WA in the figure).
.

As a result, the oil pressure discharged from the oil pressure source 3 is controlled and the oil pressure in the supply path 6 is maintained at the set value.

After it is confirmed that a certain period of time has elapsed (see reference numeral 15 in the figure), the controller sends predetermined electrical signals, that is, signals from the pressure sensor S1 in the oil passage 2b and the vehicle sensor s2 in the vehicle. Based on this, the control valve 4 is actively controlled by an electric signal outputted from the controller, thereby making it possible to control the vehicle height of the running vehicle (see reference numeral 16 in the figure).

Further, whether or not to stop the operation of the hydraulic system is determined by turning the ignition switch off (
(Symbol 17 in the figure, Sakai).

The above is the first stage control method according to the present invention, and the second stage control method according to the present invention will be explained below.

That is, when the ignition switch is turned off in order to stop the operation of the hydraulic system, the cylinder pressure in the hydraulic cylinder 2 at this time is detected by the pressure sensor Sl, and the detected value is input to the controller ( (See reference numeral 21 in the figure).

Then, the controller outputs a command signal, that is, an electric signal, corresponding to the cylinder pressure to the control valve 4 (see reference numeral 22 in the figure).

As a result, the cylinder pressure in the hydraulic cylinder 2 is maintained at the value when the hydraulic system is not in operation, that is, the expanded and contracted state of the hydraulic cylinder 2 when the hydraulic system is not in operation.

After that, the F controller operates the electromagnetic proportional relief valve 8a.
gradually release a predetermined electrical signal to (see reference numeral 23 in the figure).

That is, if there were a conventional control method, it would be normal to turn off the ignition switch and immediately release the electric signal to the electromagnetic proportional relief valve 8a, but in this invention, at least the electric signal to the electromagnetic proportional relief valve 8a The signal is supposed to be released gradually.

As a result, the oil pressure in the supply path 6 is gradually reduced.

After that, the control valve 4 is given a command from the controller 1.
(See reference numeral 24 in the figure).

By the above-described operation, even if the oil pressure is reduced on the supply path 6 side of the hydraulic system, the oil pressure is gradually reduced, and therefore a sudden oil pressure drop on the supply path 6 side is not caused.

Also, when the electric signal to the control valve 4 is released,
As shown in FIG. 2, the control valve 4 is placed in the discharge position and allows the pressure oil from the hydraulic cylinder 2 to be discharged to the tank 5 side. Since the pilot pressure to the installed operating check valve 7a is released, the operating check valve 78
It functions as a so-called check valve, and therefore prevents the discharge of pressure oil from the hydraulic cylinder 2, thereby preventing a decrease in the cylinder pressure in the hydraulic cylinder 2, that is, a decrease in the vehicle height. .

And after that, by turning off the power to the controller (
(see reference numeral 25 in the figure), and the operation of the hydraulic system can be completely stopped (see reference numeral 26 in the figure).

In the embodiment described above, the electric signal to the electromagnetic proportional relief valve 8a is gradually released to prevent a sudden drop in oil pressure in the supply path 6 of the hydraulic system. It is also possible to change the electrical signal to the relief valve 8a so as to gradually increase it so as not to cause a sudden drop in the oil pressure on the supply path 6 side.

〔Effect of the invention〕

As described above, according to the present invention, the so-called oil pressure on the supply side is not suddenly reduced when the operation is stopped, and therefore, the electromagnetic proportional relief valve that sets the oil pressure in the supply path, as well as the electromagnetic proportional relief valve, The so-called Hartz impact noise caused by high-speed switching of the operating check valve installed in the exhaust path and the switching valve installed in the communication path is no longer generated, and it is useful for hydraulic systems such as active suspension systems as vehicle suspension systems. There are some advantages that make it ideal for use.

In addition, according to the present invention, noise, so-called valve impact noise, is no longer generated in each valve section, so that no shocking operating state occurs in each response, and therefore, even if the hydraulic system is repeatedly stopped. This has the advantage that malfunctions due to breakage of components of each valve itself will no longer occur, and malfunctions or inoperability of the hydraulic system will no longer occur.

[Brief explanation of drawings]

FIG. 1 is a flow chart showing a method for controlling a hydraulic system according to an embodiment of the present invention, and FIG. 2 is a circuit diagram showing an active suspension system as a hydraulic system according to an embodiment of the present invention. (Explanation of symbols) 2...Hydraulic cylinder 2a...Oil chamber 3...-
Hydraulic source 4... Control valve 5... Tank
6... Supply path 7... Discharge path 7a... Operate check valve 8.9... Communication path 8a... Solenoid proportional relief valve 9a... Switching valve agent Person

Claims (1)

[Claims] Supplying hydraulic pressure from a hydraulic source to an oil chamber of a hydraulic cylinder via a control valve to increase cylinder pressure in the hydraulic cylinder, or discharging hydraulic pressure from the oil chamber to a tank via a control valve. A communication passage formed to reduce the cylinder pressure in the hydraulic cylinder and arranged between a supply passage that communicates between the hydraulic source and the control valve, and a discharge passage that communicates between the tank and the control valve. It has an electromagnetic proportional relief valve that sets the oil pressure in the supply path, and has an operated check valve in the discharge path that operates using the oil pressure in the supply path as pilot pressure and allows the oil pressure from the control valve side to be discharged to the tank side. and a switching valve that operates using the oil pressure in the supply path as pilot pressure and allows the oil pressure to be discharged from the control valve side to the tank side, in the communication path that communicates the control valve and the discharge path. In a method for controlling a hydraulic system configured to release electric signals to a control valve and an electromagnetic proportional relief valve when the operation of the hydraulic system is stopped, the cylinder in a hydraulic cylinder is An electrical signal corresponding to the pressure is input to the control valve so that the control valve is maintained in the set operating state, and then the electrical signal to the electromagnetic proportional relief valve is gradually released, and then the electrical signal to the control valve is A method for controlling a hydraulic system, comprising: being configured to release an electrical signal.