JPH0623447Y2 - Attitude control device for vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a vehicle attitude control device, and more specifically,
The present invention relates to a low current consumption control device having a fail-safe function in preparation for an abnormal situation in a control system and a vehicle height holding function during long-term parking with the engine stopped.

[Conventional technology]

A vehicle attitude control device using conventionally known active suspension control means sends hydraulic oil from an engine-driven oil pump under pressure accumulation by a main accumulator, while detecting vehicle body conditions by a vehicle height sensor or suspension cylinder internal pressure sensor. By operating the control valve according to the detected information to supply and discharge the hydraulic oil to and from the suspension cylinder, the vehicle height can be kept constant or the vehicle can be installed at an arbitrary height position.

Then, in such a mechanism, usually, an auxiliary device consisting of a gas spring accumulator and a damping force valve is attached to the cylinder to determine the displacement of the cylinder due to the control valve operation similarly to the mechanism having a metal spring shock absorber. I am prepared to get it.

[Problems to be solved by the invention]

By the way, with this kind of attitude control device, if the vehicle height and the like are adjusted only at a specific time such as when the vehicle starts, it is possible to supply and discharge the hydraulic oil to and from the suspension cylinder by opening and closing a poppet valve or a check valve. However, when continuous control is intended according to the situation at any time while the vehicle is traveling, a spool valve having excellent responsiveness and controllability is applied as the control valve.

However, according to the device configuration using such a spool valve,
When the vehicle is parked for a long time while the engine is stopped, the vehicle height may drop due to oil leakage from the spool sliding fitting gap of the valve.

Also, when something abnormal occurs in the control system during sudden turning of the vehicle, and the control operation suddenly stops, following this, when turning ahead of the vehicle body that went straight ahead The tilt (front and rear, left and right) control state remains as it is, and there is an inconvenience that the vehicle height gradually decreases due to oil leakage from the spool gap while continuing traveling.

In view of the drawbacks of the conventional device, the present invention has a fail-safe function for coping with an abnormal situation of the control system during traveling, and does not change the vehicle height position even during long-term parking with the engine stopped. The purpose is to develop an attitude control device.

[Means for solving problems]

Therefore, in the present invention, in order to achieve the above-mentioned object,
In a posture control mechanism that applies a hydraulic oil supply pressure from an oil pump to a suspension cylinder under a pressure reducing process by a control valve, a bypass circuit to an oil tank having a normally open solenoid valve in the supply pressure circuit is provided. Along with being attached, the supply pressure circuit is branched into a front wheel side circuit and a rear wheel side circuit each equipped with an independent accumulator, and the static load equivalent pressure preset for each of the both side circuits is used as the pilot pressure. The normally closed type switching valves that open and close are arranged at the branch positions of these two side circuits respectively, while the normally closed type that opens and closes in the hydraulic oil discharge circuit from the front wheel side and the rear wheel side using the supply pressure as the pilot pressure. We propose a vehicle attitude control system with a switching valve.

[Action]

The bypass circuit attached to the supply pressure circuit from the oil pump keeps the circuit closed while the normally open solenoid valve is energized.
It functions to supply the hydraulic oil under the proper supply pressure to the suspension cylinder side, and when the abnormality is generated, the on / off valve is switched to the normally open position when the energization is stopped manually or by the automatic control by the sensor detection. Since the hydraulic fluid sent from the pump is short-circuited back to the reservoir tank through the circuit, it serves to reduce the supply pressure on the pump side and the accumulator internal pressure on the cylinder side.

When the circuit pressure (accumulator internal pressure) drops to a preset pilot pressure (static load equivalent pressure) while the hydraulic oil supply circuit pressure is decreasing, the two normally closed switching valves are sequentially operated. It operates to individually close the front and rear wheel branch circuits on the cylinder side.

That is, with this closing, each branch circuit is in a state where the internal pressure of the accumulator is maintained at the static load equivalent pressure set for each circuit.

On the other hand, when the supply pressure drops, another normally closed switching valve that uses this as a pilot signal closes the discharge circuit, so the front wheel side circuit system and the rear wheel side circuit system are cut off from the pump side supply and discharge circuit system. Then, they are placed under the pressure equivalent to those static loads.

If the front wheel side circuit system and the rear wheel side circuit system placed in this shut-off state are left as they are, oil leakage from the spool gap in the control valve in each system will cause a gap between the left and right wheel sides due to control immediately before shut-off. The imbalance in the cylinder pressure (inclination of the vehicle body to the left and right) is gradually averaged (vehicle body horizontal).

The oil pump whose load is reduced by opening the bypass passage does not apply an excessive load to the drive engine, and therefore can continue to run as it is.

Further, the interruption on the cylinder side also occurs due to the gradual decrease of the supply pressure due to the stop of the engine. Therefore, the same action as described above can prevent a vehicle height drop in a vehicle stopped or left for a long time.

〔Example〕

 Next, an embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a circuit configuration diagram showing an embodiment of the present invention, and FIG. 2 is a longitudinal sectional view showing an example of a control valve therein, showing a hydraulic oil discharged from an oil pump 1 driven by an automobile engine, A check valve 4 for preventing backflow under a constant supply pressure by the action of a relief valve 3 provided between the reserve tank 2 and the reserve tank 2.
It is configured to be sent out toward the suspension cylinder side control circuit system of each wheel via.

The suspension cylinder side control circuit system is divided into a front wheel side F and a rear wheel side R, the hydraulic oil supply circuit is branched and connected to both sides F and R, and
Main accumulators 5 and 6 are attached to the supply circuits on both sides F and R, respectively.

Further, each of the control systems on both sides F and R is provided with a damping force valve 9 by adjusting the supply / discharge of the hydraulic oil to / from the suspension cylinder 7 by a flow control valve with pressure compensation 8 as in the case of a conventionally known device configuration. The change of the cylinder 7 is determined under the action of the gas spring 10.

In addition to the basic structure of the control system, a normally open solenoid valve is provided between the supply circuit and the discharge circuit to the reserve tank 2.
A bypass circuit in which 11 and a throttle 12 are arranged in series is provided, and a normally closed type operation check valve 13 that is opened and closed by using the supply pressure as a pilot signal is arranged in the discharge circuit.

Further, normally closed type operation check valves 14 and 15 are arranged at the base of the circuit branched to the front wheel side F and the rear wheel side R (upstream side of the accumulator 5 or 6).

And, the normally closed type operation check valves 14 and 15 are
As shown in FIG. 2, the structure is shown in FIG. 2 in which the energy storage spring 19 is provided in the communication passage 18 between the pump-side connection port 16 of the supply circuit and the cylinder-side circuit connection port 17 so as to prevent the backflow from the cylinder side. A biased poppet 20 is arranged, a pilot pressure passage 21 is provided in parallel with the communication passage 18, and one end is pushed by an adjusting screw shaft 22 that can be operated from the outside. An adjustable check valve 25 constituted by pressing a supported poppet 24 against the port 17 is provided in the passage 21, and a rod tip of a spool 28 with an orifice 27 slidably fitted in a tube portion 26 of the passage 21. 29 is faced to the head of the poppet 20.

On the other hand, the respective discharge circuits for the hydraulic oil from the front and rear sides F and R are connected together toward the operating check valve 13, and the rear wheel side R is included in each of the discharge circuits.
Check valve 30 for preventing the inflow of hydraulic oil from the discharge circuit on the front wheel side F, which is the side with a heavy shared static load due to the engine being mounted on (the side with a light shared static load on the wheels) 30
Further, the suspension cylinders 7 of the left and right wheels on the front and rear wheel sides F and R are connected by a throttle passage 32 which is connected or closed by a normally open electromagnetic opening / closing valve 31.

According to the embodiment having such a configuration, by closing the normally open electromagnetic on-off valve 11 that is energized at the same time as the engine is started, the hydraulic oil discharged from the oil pump 1 driven by the engine causes pressure to be applied to the supply circuit. Occurs. Due to this supply pressure, the normally closed type operation check valve 13 of the discharge circuit opens, and the hydraulic oil passes through the normally closed type operation check valves 14 and 15 of the branch circuit on the piston side, and these main accumulators Accumulated in 5 and 6.

In the front and rear sides F and R that receive the supply of hydraulic oil under such a situation, similarly to the conventional device, a signal current from the controller is given to the control valve 8 based on information from various sensors, and the control is performed by the valve 8. The respective wheels are adjusted according to the control purpose by the displacement of the cylinder 7 due to the supply or discharge of the hydraulic oil to or from the suspension cylinder 7.

Of course, during this operation, the throttle circuit 32 that connects the left and right suspension cylinders 7 is connected to the normally open solenoid valve 31.
It is closed by the energization of.

In contrast to such posture control by normal operation, the supply pressure on the pump side decreases when an abnormality occurs in the control system or when the vehicle is parked with the engine stopped.

That is, when an abnormality occurs during traveling, by manual operation or by automatic operation based on sensor information, on the other hand, during parking, by communication of a bypass circuit that cuts off the closing holding current to the on-off valve 11 in synchronization with engine stop. By dropping the hydraulic oil of the supply circuit to the discharge circuit, the supply pressure decreases, but this decrease gradually progresses due to the action of the throttle 12 in the bypass circuit.

During the progress of the decrease of the supply pressure, first, the normally closed type operation check valve 13 of the discharge circuit which uses the supply pressure as the pilot pressure is closed, and the subsequent decrease causes the normally closed type operation check valves 14 and 15 in the cylinder side branch circuit. Are closed one after another.

The closing operation of the normally closed type operation check valves 14 and 15 will be described with reference to the valve assembly shown in the second figure. The operating oil supplied from the pump side to the port 16 during the normal operation is the poppet 20.
Is pushed down to the right in the figure against the acting force of the energy storage spring 19 and passed toward the cylinder side port 17 through the gap between the communication passage 18 and the pump side. When the supply pressure at the port 16 decreases, the back pressure of the poppet 24 of the pilot pressure circuit 21 decreases due to the communication of the orifice 27 of the spool 28 on the port 16 side.

The poppet 24, which receives the accumulated pressure of the accumulator 5 or 6 of the cylinder side port 17 due to this back pressure reduction, has an urging spring 23 at the initial stage of the reduction in which the accumulated pressure is still sufficiently high.
It is pushed down to the left in the figure in balance with the acting force of.

Therefore, in communication with the port 17 side of the pilot pressure circuit 21, the spool 28 slides the cylinder portion 26 to the right in the figure, and the tip end 29 of the spool 28 stores the poppet 20 in the communication passage 18 to store energy. Push down in the same direction against the action force of.

As a result, the communication passage 18 is opened, and the hydraulic oil stored under pressure in the accumulator 5 or 6 is stored in the port 17
Flows back from the side to port 16 side. That is, in the initial stage of the supply pressure reduction due to the opening of the bypass passage, the accumulated pressure of the accumulator 5 or 6 in the cylinder side branch circuit also decreases due to the backflow of the hydraulic oil.

And this state is the poppet 2 of the pilot pressure circuit 21.
4 is returned to the closed position due to the force relationship between the pressure on the port 16 side and the acting force of the urging spring 23, which is continued until the poppet 20 is returned and closed by releasing the pressing of the spool 28 having the orifice 27. .

Therefore, the acting force of the biasing spring 23 is adjusted by the adjusting screw shaft 22.
The pressure on the port 17 side when the poppet 24 is returned and closed, that is, the internal pressure of the cylinder side control system by the accumulator 5 or 6 is adjusted to a constant cylinder against the static load of the vehicle body shared by the front and rear wheels. By adjusting in advance to a pressure capable of maintaining the displacement (static load equivalent pressure), the control system of the front wheel side F and the rear wheel side R, that is, the internal pressure of the suspension cylinder 7 corresponds to such load equivalent pressure. Then, the operate check valve 14 or 15 is switched to the closing side.

In this way, the front wheel side F and the rear wheel side R, which are shut off from the pump side by closing the hydraulic oil supply circuit and the above-mentioned drain circuit,
There was no hydraulic oil inflow from the front wheel side F set to a high load equivalent pressure by the blocking action of the check valve 30 provided in the rear wheel side R discharge circuit, and these control systems were maintained independently. It is in a state of being

Therefore, the normally open solenoid valve in the bypass circuit described above
Cylinder side normally open solenoid on-off valve controlled in synchronization with 11
Since the throttle passage 32 communicates between the left and right suspension cylinders 7 by opening the valve 31, the internal pressure of the cylinders 7 is balanced between the left and right wheels on the front wheel side F and the rear wheel side R, and The left-right tilt is automatically corrected.

As a result, the inclination in the front-rear direction of the vehicle body is corrected while maintaining the internal pressure corresponding to the static load of the vehicle body shared by the front wheel side F and the rear wheel side R, and the equalization of the internal pressures between the left and right wheels is measured. Therefore, it is possible to keep the vehicle body horizontal while maintaining a predetermined vehicle height position after a control type abnormality including the hydraulic pressure supply side and during long-term parking with the engine stopped.

Therefore, according to the configuration of the embodiment of the present invention which operates as described above, the switching valve in the device of the present invention is not limited to the operated check valve shown in the drawings, and it opens at a predetermined value or more of the supply pressure and closes at a predetermined value or less. Any structure that can be used, that is, as shown in FIG. 3, the pressure oil sent from the pump 1 pushes the poppet 31 in the check valve body 30 against the spring 32 and opens the cylinder port 17 side. Shed.

On the other hand, when an abnormality occurs, the pressure oil accumulated in the accumulators 5 and 6 acts on the poppet 35 in the relief valve main body 34 from the orifice 33 to open the poppet 35 and flow it to the pump side. At this time, the check valve body 30
Since pressure is guided to the poppet 31 inside through the orifice 31a formed in the poppet 31, the poppet 31 is pressed against the seat surface portion of the check valve body 30 to prevent pressure oil from leaking. Also, the relief valve body 3
Since the spring 36 provided on the back of the poppet 35 in 4 is set so as to obtain a biasing force that closes when the front or rear side reaches a required pressure, the pressure on the cylinder port 17 side is set to a set value. When it does, the drainage stops and the pressure is held. Further, the control valve may be a flow control valve with pressure compensation shown in the figure as long as it can control the supply and discharge of hydraulic oil to a cylinder such as a pressure control valve.

Furthermore, the check valve arranged in the discharge circuit on the cylinder side is, of course, installed in such a way that the direction of the backflow prevention is directed toward the side where the set value of the system pressure is high, because of its function,
The passage that connects the left and right suspension cylinders is
When considering communication due to oil leakage in the control valve,
These are not necessarily required except for the purpose of averaging the inter-cylinder internal pressure as soon as possible.

[Effect of device]

As described above, according to the device of the present invention, the suspension control system is divided into the front wheel side and the rear wheel side, and independent accumulators are respectively arranged in these, and the switching valve for opening and closing the circuit is provided on the hydraulic oil supply side. Are provided so that when these two wheels are shut off from the supply side, they retain predetermined control system internal pressures, respectively.Therefore, these retained internal pressures are set as static load equivalent pressures shared by the front and rear wheels. By doing so, the vehicle body can be maintained at the vehicle height and maintained horizontally even after the occurrence of an abnormality in the control system and during the long-term parking while the engine is stopped. In addition to the fail-safe action on the control system, the vehicle body posture can be maintained. It has an excellent holding action, and the switching valve and the switching valve in the discharge circuit are composed of a valve mechanism that uses the supply pressure from the pump side as the pilot pressure, and this supply pressure is used to control the opening of one normally open solenoid valve. so The device for such control can be constructed in a relatively lightweight and bulky manner, and the electric power cost for the control operation is small, so that the above-mentioned fail-safe operation and parking are possible. The device of the present invention is extremely useful in practice as this type of device because it can exhibit excellent effects such as vehicle height maintaining action.

[Brief description of drawings]

FIG. 1 is a block diagram of a hydraulic control circuit showing an embodiment of the device of the present invention, FIG. 2 is a longitudinal sectional view showing an example of a switching valve in the device of the present invention, and FIG. 3 shows another embodiment of the switching valve. FIG. [Explanation of symbols] 1 …… Oil pump 2 …… Reservoir tank 3 …… Relief valve 5,6 …… Main accumulator 7 …… Suspension cylinder 8 …… Control valve 11,31 …… Normally open type solenoid valve 13 , 14, 15 ... Normally closed type operated check valve

Claims (6)

[Scope of utility model registration request] 1. An attitude control mechanism in which a hydraulic oil supply pressure from an oil pump is applied to a suspension cylinder under a pressure reducing process by a control valve, and an oil tank having a normally open solenoid valve in the supply pressure circuit. With a bypass circuit to the front wheel side circuit and the rear wheel side circuit each having an independent accumulator, and a static load equivalent pressure preset for each of the both side circuits. Each of the normally closed type switching valves that open and close using pilot pressure as the pilot pressure are arranged at the branch positions of these two side circuits, respectively, and the supply pressure is used as the pilot pressure to open and close the hydraulic oil discharge circuit from the front wheel side and the rear wheel side. An attitude control device for a vehicle, comprising: a normally closed switching valve that operates. 2. The vehicle attitude control device according to claim 1, wherein the control valve is a flow control valve with pressure compensation. 3. A vehicle attitude control device according to claim 1, wherein the bypass circuit is an orifice passage with a throttle. 4. The vehicle attitude control device according to claim 1, wherein the switching valve is an operating check valve. 5. A utility model registration claim, wherein when the discharge circuit is a common circuit for the front wheel side and the rear wheel side, an inflow prevention check valve is arranged in the discharge circuit on the side with the smaller static load. 11. The vehicle attitude control device according to claim 1. 6. A utility model registration claim in which each of the front wheel side circuit and the rear wheel side circuit is provided with a normally open type electromagnetic on-off valve with a throttle that connects the left and right wheel suspension cylinders to each other. The vehicle attitude control device described.