JPH0454494Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention relates to a vehicle attitude control device, and in particular,
Concerning control when a pressure control valve fails.

(Problems to be solved by conventional techniques and ideas) Conventionally, as a vehicle attitude control device, for example,
Those described in JP-A-62-96126 and JP-A-62-96109 are known.

The pressure control valves used in these conventional devices are
These valves simply control the output hydraulic pressure in proportion to the electromagnetic force of the solenoid, and do not have a safety mechanism that can deal with the case where the valve spool becomes stuck due to dirt or other debris. If a spool sliding abnormality occurs, the output hydraulic pressure will be maintained at the same level, thereby
There were problems such as the vehicle height remaining abnormal and the vehicle's attitude remaining unbalanced.

Incidentally, these conventional devices have a structure that stops control when such an abnormality occurs in the pressure control valve, so the pressure inside the attitude variable means is maintained as it is, thereby reducing the vehicle height. This device itself has a problem in that the vehicle becomes unbalanced when the pressure control valve is abnormal.

For example, as disclosed in Japanese Patent Publication No. 50-31292 and Japanese Patent Application Laid-open No. 60-54025, the safety mechanism that operates when a valve with a pressure reducing structure cannot adjust the pressure to a predetermined pressure is However, in the control valve of the present invention, which adjusts pressure by driving a solenoid and sliding a valve spool, it has not been known to operate when an abnormality in sliding of the valve spool occurs. I wasn't there.

(Means for solving the problem) The present invention solves the above-mentioned problems, and when an abnormality occurs in the pressure control valve, the output hydraulic pressure is reduced to a low pressure such as a drain pressure or a certain predetermined pressure. The present invention aims to provide a safety valve for an attitude control device that has a simple structure and high safety by having a structure in which a safety mechanism that can generate pressure is integrally provided in a valve spool of a pressure control valve.

In order to achieve this objective, the present invention includes valve holes connected to each of the pump pressure circuit, drain circuit, and output circuit, and a valve hole that is provided so as to be slidable in the axial direction of the valve hole. A first land that increases the amount of restriction between the output circuit and the pump pressure circuit by sliding, and a second land that increases the amount of restriction between the output circuit and the drain circuit by sliding in the other direction are formed. a valve spring that biases the valve spool in a direction to widen the restriction caused by the second land; and a solenoid that presses the valve spool with a plunger in a direction to widen the restriction created by the first land; In a pressure control valve whose output circuit is connected to an attitude variable means that is actuated by hydraulic pressure to control the attitude of the vehicle, a drain pressure or a predetermined pressure is applied to the solenoid side end of the valve spool coaxially with the valve spool and the plunger. A spool-side valve hole is formed that communicates with the abnormality hydraulic pressure path that generates a constant pressure and the output circuit, and the spool-side valve hole is normally supported by a safety spring with a stronger elastic force than the valve spring. A safety valve is provided that is slidably biased to a position that cuts off communication between the abnormality hydraulic pressure path and the output circuit, and is pressed by the plunger and slides in the axial direction to connect these circuits. The valve spool is provided with a stopper that restricts the sliding movement of the safety valve by the safety spring at a position where the communication is interrupted.

(Operation) The vehicle attitude control device of the present invention operates as described below.

(b) When the pressure control valve is normal Normally, a current is output to the solenoid to keep the vehicle in a predetermined target state (for example, horizontal), and this current drives the plunger to press the safety valve. do.

The pressing force of the plunger is transmitted to the valve spool via the safety valve and safety spring, and further transmitted to the valve spring that biases the valve spool toward the solenoid.

In this case, since the valve spring has a structure with a weaker elastic force than the safety spring, the valve spring is shortened without shortening the safety spring, and the valve spool slides in the direction of widening the aperture created by the first land. As a result, the output circuit and the pump pressure circuit are communicated with each other, and the output hydraulic pressure increases.

In addition, when the current to the solenoid decreases, the pressing force by the plunger also decreases, the valve spring expands, and the valve spool slides in the direction of widening the restriction formed by the second land, thereby communicating the output circuit and the drain circuit. The output hydraulic pressure decreases.

In other words, under normal output hydraulic pressure control, within the sliding stroke range of the valve spool, only the valve spring expands and contracts, and the safety spring does not expand or contract.As a result, the safety valve maintains the regulated position by the stopper, and the output increases. Communication between the circuit and the emergency hydraulic pressure path is cut off.

(b) When an abnormality occurs in the pressure control valve In the pressure control valve, an abnormality may occur in which the valve spool becomes stuck and the valve spool does not slide.

In this case, if you drive the solenoid,
Since the valve spool does not slide, the pressing force of the plunger is not transmitted to the valve spring, and this pressing force shortens the safety spring, causing the safety valve to slide away from the stopper through the spring-side valve hole. The output circuit is communicated with the emergency hydraulic pressure path.

As a result, the output hydraulic pressure of the pressure control valve is maintained at a low pressure such as a drain or a certain predetermined hydraulic pressure, and the attitude variable means is also in a predetermined state, so that the vehicle attitude is stabilized. do.

Also, if a current higher than the current during normal control is applied to the solenoid to increase the pushing force of the plunger, the safety spring will shorten after the valve spring has been shortened by a predetermined amount, causing the pressure control valve to shorten. The output hydraulic pressure can be set to drain pressure or a predetermined pressure.

(Example) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

First, the structure of the first embodiment shown in FIGS. 1 to 4 will be explained.

FIG. 2 shows a pressure control valve 20 according to the first embodiment of the present invention.
1 is an overall view showing an attitude control device for a vehicle equipped with a vehicle attitude control device, in which reference numerals 10, 10, 10, and 10 indicate attitude control actuators as attitude changing means. This attitude control actuator 10 is installed between the axle and the vehicle body at four locations on the front, back, left, and right of the vehicle body, in parallel with a suspension device (not shown), and includes a cylinder 11 whose lower end is supported on the axle side, and a cylinder 11 whose lower end is supported on the vehicle body side. A piston 12 whose upper end is supported and slides within a cylinder 11 is provided, and the distance between the vehicle body and the axle is adjusted by the sliding movement of the piston 12.

That is, the piston 12 defines the inside of the cylinder 11 into a pair of working chambers 13 and 14, and the working chamber 14 has an output circuit 101 from each pressure control valve 20.
Hydraulic fluid is supplied through. When the hydraulic pressure in the working chamber 14 increases, the piston 12 moves upward and lifts the vehicle body, and when the hydraulic pressure in the working chamber 14 decreases, the piston 12 moves downward and lowers the vehicle body. In this way, the attitude control actuator 10
The system controls the attitude of the vehicle by adjusting the height of the vehicle at four locations: front, rear, left, and right.

Note that the piston 12 may be provided with a communication hole 15.

Although oil is generally used as the hydraulic fluid, it is not limited to oil as long as it is a fluid that can satisfactorily transmit hydraulic pressure. Further, as shown in the figure, the pressure control valve 20 is configured to be supplied with the hydraulic pressure of the pump 103 stored in the accumulator 102, and there is a check valve between the pump 103 and the accumulator 102. A valve 104 is provided, and an unload valve 105 is interposed in parallel.

In the pressure control valve 20 of the first embodiment, a solenoid 21 is driven by a control signal Ci from a controller 30 to slide a valve spool 22, thereby controlling the output hydraulic pressure to the attitude control actuator 10.

As shown in the sectional view of FIG. 1, this pressure control valve 20 has a valve hole 24 formed in a valve body 23, and a pump pressure circuit 1
Pump pressure port 2 to which pump pressure P is supplied from 6
41, a drain port 242 communicating with the tank 108 and an output port 243 communicating with the output circuit 101 are formed in the drain circuit 107, and the valve hole 24 has back chambers 244, 245 at both ends.
A valve spool 22 is slidably provided so that the lands 221 and 222 can change the amount of restriction of the pump pressure port 241 and the drain port 242 to adjust the output hydraulic pressure.
Furthermore, a reaction land 223 is formed at the left end of the valve spool 22 in the figure, and the valve spool 22 and the valve body 23 at this position are communicated with an output port 243 and a fluid path 231, so that feedback fluid pressure is introduced. A feedback chamber 246 is formed.

Further, the valve spool 22 is urged to a neutral position by valve springs 25, 25, and is pushed by a plunger 211 of the solenoid 21 in a direction to increase the output hydraulic pressure. Note that both the back chambers 244 and 245 are communicated with the drain circuit 107.

Therefore, when the solenoid 21 is not driven, the valve spool 22 is connected to both valve springs 2.
The pump pressure port 241, the drain port 242, and the output port 243 are each independent. When the solenoid 21 is driven, the plunger 211 pushes the valve spool 22 to the right in the figure, causing the valve spool 22 to slide, opening the throttle of the pump pressure port 241, closing the throttle of the drain port 242, and closing the throttle of the output port 243. hydraulic pressure is increased. This increased hydraulic pressure is led to the feedback chamber 246 via the liquid path 231 and is received by the reaction land 223 in the opposite direction to the pressing direction of the plunger 211. It is pushed back to a position where the received pressure is balanced, and the output hydraulic pressure is controlled to a pressure proportional to the electromagnetic force of the solenoid 21.

Further, this actual output hydraulic pressure Ps is detected by a pressure sensor 40 as pressure detection means provided in the pipe line (FIG. 3).

By the way, as shown in FIG. 1, a safety valve 51 is provided between the valve spool 22 and the plunger 211. This safety valve 51 operates in the event of an abnormality and turns the hydraulic pressure of the output port 243 into a drain pressure.This safety valve 51 is formed at one end of the valve spool 22 (the left end in the figure), and 246 and the back chamber 244 so as to be slidable therein, and is biased by a safety spring 54 until the stopper ring 53 restricts the sliding movement. It should be noted that this safety spring 54 has a considerably stronger resiliency than the valve spring 25. Further, the back chamber 244 communicating with the spool-side valve hole 52 is used as a liquid path for use in an abnormal situation where the drain pressure is always maintained, as will be described later.

Further, an annular chamber 55 is formed in the spool-side valve hole 52 . This annular chamber 55 is connected to the feedback chamber 246 (i.e., the output circuit 10
1), and in a state where the safety valve 51 is in a position where sliding is restricted by the stopper ring 53 shown, the safety valve 51 is blocked, and the safety valve 51 is slid to the back of the spool side valve hole 52. In the state
Back chamber 24 as a hydraulic pressure path in case of abnormal drain pressure
4.

Therefore, when the plunger 211 presses the safety valve 51, the pressing force transmitted to the valve spool 22 via the safety valve 51 and the safety spring 54 causes the valve to close before the safety spring 54 shortens. The spring 25 is shortened, the valve spool 22 slides, and the output hydraulic pressure is controlled as described above. Also, if there is any abnormality in the sliding of the valve spool 22,
Due to the sliding resistance and the strong pressing force described below, the safety spring 54 is shortened and the safety valve 51 is pushed deep into the spool side valve hole 52, and the annular chamber 55 is communicated with the back chamber 244. , the output port 243 connects to the drain circuit 107 via the feedback chamber 246 and the back chamber 244.
The output hydraulic pressure is lowered to the drain pressure Pt.

Therefore, this safety valve 51 and safety spring 5
4. Safety mechanism 50 that forcibly sets the output hydraulic pressure of the pressure control valve 20 to the drain pressure Pt by the annular chamber 55
is configured.

Note that the safety valve 51 is connected to the back chamber 2 by controlling the hydraulic pressure in the annular chamber 55.
44 is formed.

The controller 30 is composed of a CPU 31, a ROM 32, a RAM 33, an input interface 34, and an output interface 35, as shown in FIG.

The input interface 34 is connected to the input sensor group 60
It inputs a signal from the CPU 31 and converts it into a signal that can be processed by the CPU 31.

The input sensor group 60 includes acceleration Gx acting on the left and right sides of the vehicle body, and acceleration Gx acting on the front and rear of the vehicle body.
Gy, G sensors 61, 62, 63 that detect the acceleration Gz acting on the top and bottom of the vehicle body, and the output hydraulic pressure of each output circuit 101, 101, 101, 101
Pressure sensor 40, 40, 40, 4 that detects Ps
Contains 0.

The control operation of the controller 30 will be explained with reference to the flowchart of FIG.

In step a, each acceleration is input from the input sensor group 60.
Gx, Gy, Gz and actual output hydraulic pressure Ps, Ps, Ps, Ps
is loaded.

Then, in step b, based on this input information, when the attitude of the vehicle changes, such as when loading cargo, accelerating/decelerating, or cornering, the attitude control calculation means determines whether the attitude of the vehicle is, for example, horizontal. The pressure control valve 2 is adjusted based on data stored in the ROM so that a predetermined target state is achieved.
The required output hydraulic pressure is calculated at 0.

Based on this calculation result, in step c, a control signal Ci is outputted to the solenoid 21 of each pressure control valve 20 from a portion of the output interface 35 corresponding to the normal signal generating means. This control signal Ci is a current, and the current value of the control signal Ci is in the range of 0 to 1.0A.

Further, in step d, this CPU 31 compares the actual output hydraulic pressure Ps read from each pressure sensor 40 with the calculated output hydraulic pressure Pg for each pressure control valve 20 by the attitude control calculation, and operates the pressure control valve 20. The first determination is made as to whether or not the process is being performed normally. That is, both output hydraulic pressure
When Pg and Ps are equal, it is judged as normal, and the above steps a to d are repeated, and both output hydraulic pressures are
When a difference occurs between Pg and Ps, it is determined that an abnormality has occurred, and the process proceeds to step e.
Now, the deviation ΔS between the actual output hydraulic pressure Ps and the calculated output hydraulic pressure Pg is calculated according to the following equation.

ΔS=Pg−Ps Next, in step f, a second abnormality determination is performed, and the previous deviation ΔSn−1 and the current deviation ΔSn
Compare the pressure control valve 2 and if it changes, pressure control valve 2.
0 is operating normally without any sliding abnormality, and outputs a deviation signal corresponding to the deviation ΔS in step g. Next, in step h, the current value of the control signal Ci to the solenoid 21 is corrected based on the deviation signal.

After that, return to step d, perform the above-mentioned determination,
If both output hydraulic pressures Pg and Ps match and are determined to be normal, the current process is terminated, and if they do not match, the above-mentioned steps d to h are repeatedly executed. That is, in steps d to h, feedback control is performed so that the actual output hydraulic pressure Ps generated at the output port 243 of the pressure control valve 20 matches the calculated output hydraulic pressure Pg.

On the other hand, when the deviation ΔS does not change at step f, the valve spool 22 of the pressure control valve 20
It is determined that there is a sliding abnormality, and in step i, an actuation signal Sj for actuating the safety valve 51 is output from a portion of the output interface 35 corresponding to the abnormality signal output means, and at the same time, other normal pressures are detected. The output of the control signal Ci to the control valve 20 is stopped in order to make the output hydraulic pressure equal to the drain pressure Pt.

In addition, the actuation signal Sj must be a current that can generate enough electromagnetic force to cause the solenoid 21 to reliably slide the safety valve 51 against the elastic force of the safety spring 54, so in reality,
A higher current (1.5-2.0A) than the control signal Ci is used.

Next, the operation of the embodiment will be explained.

(a) When the pressure control valves are normal When the pressure control valves 20, 20, 20, and 20 are normal, the controller 30 performs the control operation by adding steps a to d or steps e to h. and the pressure control valve 20
A control signal Ci, which is a current within the range of 0.0A to 1.0A, is output.

With the pressing force from the plunger 211 due to this control signal Ci, only the valve spring 25 expands and contracts, the valve spool 22 slides, and the output hydraulic pressure is controlled so that the vehicle body is brought into a predetermined target state. The safety valve 51 does not slide so far that the annular chamber 55 and the back chamber 244 are communicated with each other.

(b) When an abnormality occurs in the pressure control valve When an abnormality occurs in one of the pressure control valves 20, such as the valve spool 22 becoming stuck, first, the actual output hydraulic pressure Ps of the pressure control valve 20 is
is different from the calculated output hydraulic pressure Pg by the attitude control calculation means.

In step d, the difference between Ps and Pg is determined, and if it is determined in step f that an abnormality has occurred, in step i, the output interface 35 sends an operating signal Sj (1.5 to 2.0 A high current) is output, and other normal pressure control valves 20, 20, 2
0, the output of the control signal Ci is stopped.

In the case of the pressure control valve 20 in which an abnormality has occurred, when the activation signal Sj is applied to the solenoid 21 and the safety valve 51 is pushed with a large pressing force, the valve spool 22 becomes stuck and the sliding resistance is extremely large. Also, the safety valve 51 slides by shortening the safety spring 54 so that the annular chamber 55 is connected to the back chamber 24.
It is communicated with the 4th side, and the output hydraulic pressure becomes the drain pressure Pt.
Further, even if the abnormality is in a part other than the valve spool 22, if the valve spool 22 slides greatly due to the large pressing force given by this actuation signal Sj and the valve spring 25 no longer shortens, the safety spring 54 will still be shortened. safety valve 5
1 slides, and the output hydraulic pressure becomes the drain pressure Pt.

Therefore, the output hydraulic pressure of all the pressure control valves 20 becomes the drain pressure Pt, and the attitude control actuator 1
0 is a shortened state where all the lengths are the same, the vehicle height at four locations is the same, and the vehicle body is in a general state supported only by the suspension device, that is, the same as the posture of a vehicle without an attitude control device. The state has become
Running becomes stable.

As described above, the safety mechanism 50 including the safety valve 51 has a feature that the output hydraulic pressure is not maintained at abnormal times but becomes the drain pressure.

Furthermore, the first embodiment has a feature of high responsiveness because an abnormality in the pressure control valve 20 is detected based on a comparison between the actual output hydraulic pressure Ps and the calculated output hydraulic pressure Pg.

Next, a second embodiment shown in FIG. 5 will be described. This second embodiment is configured such that the output hydraulic pressure of the pressure control valve 20 becomes a predetermined constant pressure when the safety mechanism 50 is activated.

FIG. 5 is a sectional view showing the valve spool 22 of the second embodiment, and the safety valve 51 has a land 51.
2,513 and a safety valve side port 514 are formed. Further, the spool side valve hole 52 is formed with a hydraulic pressure port 521 connected to an abnormality liquid path 561 through which hydraulic pressure is introduced from the pump pressure port 241 via the pressure reducing valve 56.

Further, the control operation of this second embodiment is as shown in FIG.

Therefore, when an abnormality occurs in the pressure control valve 20, when the actuation signal Sj is output from the controller 30 (step j in FIG. 6), the plunger 211 is pressed and the safety valve 51 is slid, and the safety valve side port is opened. 514 allows hydraulic port 521 and annular chamber 55 to communicate with each other. As a result, the hydraulic pressure in the annular chamber 55 and the output port 243 communicating with the annular chamber 55 becomes a predetermined hydraulic pressure reduced by the pressure reducing valve 56.

At the same time, the controller 30 sends a control signal to other normal pressure control valves 20 to make the output hydraulic pressure equal to this predetermined hydraulic pressure (for example, a predetermined pressure according to the axle load). Cj is output (step j).

As a result, the attitude control actuators 10 at four locations on the vehicle body are all set to the same predetermined length, and the vehicle body is maintained in the same normal state as a general vehicle, and the pressure control valve 20 is prevented from malfunctioning. The running is also stable. The vehicle height at this time is slightly higher than in the first embodiment.

In this second embodiment, other configurations and operations are the same as those in the first embodiment, so explanations thereof will be omitted.

(Effects of the invention) As explained above, in the vehicle attitude control system of the present invention, a safety valve is provided in the valve spool of the pressure control valve to communicate the output circuit with the abnormality hydraulic pressure path in the event of an abnormality. The structure is simple and inexpensive, and the hydraulic pressure in the output circuit is not maintained as it is when an abnormality occurs, but is maintained at a low pressure such as drain pressure or a certain predetermined pressure. The advantage is that a pressure control valve can be provided that increases the safety and reliability of the control device.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a pressure control valve for an attitude control device according to a first embodiment of the present invention, FIG. 2 is an overall view showing an attitude control device equipped with the device of the first embodiment, and FIG. A block diagram showing the controller of the example device,
FIG. 4 is a flowchart showing the control operation of the controller of the first embodiment, FIG. 5 is a sectional view showing the valve spool and safety valve of the pressure control valve of the second embodiment, and FIG. 6 is a flowchart showing the control operation of the controller of the second embodiment. 7 is a flowchart showing the control operation of the controller. 10... attitude control actuator (attitude variable means), 20... pressure control valve, 21... solenoid,
22... Valve spool, 24... Valve hole, 2
5... Valve spring, 51... Safety valve, 52
... Spool side valve hole, 54 ... Safety spring, 101 ... Output circuit, 106 ... Pump pressure circuit, 107 ... Drain circuit, 211 ... Plunger, 244 ... Back chamber (hydraulic pressure path for abnormal situations) , 561
...Hydraulic pressure path for emergency situations.

Claims (1)

[Claims for Utility Model Registration] A valve hole 24 connected to each of the pump pressure circuit 106, the drain circuit 107, and the output circuit 101;
provided so as to be slidable in the axial direction of the valve hole 24;
The first land 221 widens the amount of restriction between the output circuit 101 and the pump pressure circuit 106 by sliding in one axial direction, and the output circuit 10 by sliding in the other direction.
The valve spool 2 is formed with a second land 222 that increases the amount of restriction between the valve spool 1 and the drain circuit 107.
2 and the valve spool 22 to the second land 22
2, and a solenoid 21 that presses the valve spool 22 with a plunger 211 in a direction to widen the restriction caused by the first land 221. In the pressure control valve, the output circuit 101 is connected to the attitude variable means 10 that controls the attitude of the valve, the drain pressure or a predetermined constant pressure is applied to the solenoid side end of the valve spool 22 coaxially with the valve spool 22 and the plunger 211. A spool side valve hole 52 is formed which communicates with the abnormal hydraulic pressure passages 244, 107 and the output circuit 101, which generates an abnormality. Due to the force safety spring 54, the abnormality hydraulic pressure path 244,
107 and the output circuit 101, and is pressed by the plunger 211 and slides in the axial direction to bring these circuits into communication. The safety spring 5 is attached to the spool 22.
4. A pressure control valve for an attitude control device, characterized in that a stopper 53 is provided for regulating the sliding movement of the safety valve 51 caused by the pressure control valve 51 at a position where the communication is cut off.