JPH05248556A - Fluid pressure control valve - Google Patents

Abstract

PURPOSE:To improve control accuracy at a time when control responsiveness is required due to an increase in control response speed in a fluid pressure control valve using a piezoelectric element as an actuator. CONSTITUTION:At least one set of piezoelectric elements A, B and C in an axial direction, and two sets thereof in a direction vertical to an axial line are respectively arranged in a spool 6, and constitution is so made that the spool 6 itself can repeatedly move by constant unit length via the expansion and contraction of the elements A, B and C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluid pressure control valve which is applied to an active hydraulic suspension system or the like and uses a piezoelectric element as an actuator.

[0002]

2. Description of the Related Art Heretofore, as an actuator in which a solenoid is used as an actuator of a fluid pressure control valve, for example, one disclosed in Japanese Utility Model Laid-Open No. 64-21878 is known.

Further, as the actuator of the fluid pressure control valve in which a piezoelectric element is used instead of the solenoid, for example, those described in JP-A-59-135784 and JP-A-63-136581. It has been known.

According to these conventional sources, a pilot pressure is generated according to a control command to a solenoid or a piezoelectric element, and when the pilot pressure is higher than the control pressure, the spool moves so as to connect the supply port and the control port. On the contrary, when the pilot pressure is lower than the control pressure, the spool moves so as to connect the return port and the control port,
When the pilot pressure and the control pressure are the same, the spool moves to the position that closes the supply port and the return port, so that the differential pressure between the pilot pressure according to the control command and the control pressure being fed back is eliminated. A valve is shown to operate the spool and control the fluid pressure.

[0005]

However, in the above-mentioned conventional fluid pressure control valve, the spool, both ends of which are supported by the spring, is operated by the fluid force due to the differential pressure between the pilot pressure and the control pressure. Since the fluid pressure is controlled by, the pilot pressure is first generated by the control command, then the fluid pressure acts on the spool after the pilot pressure is released, and the fluid force causes the spool to oscillate. Otherwise, the target control pressure cannot be obtained, and the response speed for obtaining the target control pressure from the control command is low.

By the way, the conventional fluid pressure control valve has a response speed of 10 Hz or less, and when control response is required, the control accuracy is poor.

For example, when the conventional fluid pressure control valve is applied to an active hydraulic suspension system, although a response speed in the sprung resonance frequency range of about 1 Hz is secured,
In the unsprung resonance frequency range of 0 Hz or higher, the desired damping force characteristics cannot be obtained due to the response delay of the control pressure.

The present invention has been made by paying attention to the above problems, and in a fluid pressure control valve using a piezoelectric element as an actuator, control is performed when control response is required by increasing control response speed. The challenge is to improve accuracy.

[0009]

In order to solve the above problems, in the fluid pressure control valve of the present invention, at least one set of piezoelectric elements is arranged in the spool in the axial direction and two sets of piezoelectric elements are provided in the direction perpendicular to the axis, and the spool itself is provided with the piezoelectric elements. By expanding and contracting, it is possible to repeat the operation of moving in fixed length units.

That is, the supply port formed in the valve hole,
A return port and a control port, a spool disposed in the valve hole so as to be movable in the axial direction, and a spool for switching the supply port and the return port to generate a control pressure to the control port, and at least one set interposed in the axial direction of the spool, It is characterized in that it is provided with two piezoelectric elements interposed in the direction perpendicular to the axis.

[0011]

Operation: For example, the operation when the spool is moved to the left will be described.

Here, one set of piezoelectric elements interposed in the axial direction of the spool is an intermediate piezoelectric element, and two sets of piezoelectric elements interposed in the direction perpendicular to the axis are a left piezoelectric element and a right piezoelectric element, respectively. First, a voltage is applied to the right piezoelectric element to expand it. As a result, the right piezoelectric element is locked in the valve hole, and the spool movement from the current position to the right is restricted.

Next, a voltage is applied to the intermediate piezoelectric element to expand it. As a result, the spool moves to the left.

Next, a voltage is applied to the left piezoelectric element to expand it. As a result, the spool is fixed at the position moved to the left.

Next, the voltage applied to the right piezoelectric element is cut off and shortened. As a result, the lock of the right piezoelectric element with respect to the valve hole is released.

Next, the voltage applied to the intermediate piezoelectric element is cut off and shortened. As a result, the intermediate piezoelectric element moves leftward together with the right piezoelectric element.

Next, a voltage is applied to the right piezoelectric element to expand it. This locks the right piezoelectric element in the valve hole,
Spool movement from the current position to the right is restricted.

Next, the voltage applied to the right piezoelectric element is cut off and shortened. As a result, the spool is moved to the left as a whole, and the state is exactly the same as that at the beginning.

The spool can be moved to the left by repeating the above-described operation of moving in a unit of a fixed length in a scaled manner. When moving the spool to the right, the left and right operations may be reversed.

Here, by repeating the operation of moving in the unit of a fixed length for one cycle, only the spool moving amount corresponding to the expansion amount of the intermediate piezoelectric element can be earned, but the piezoelectric element applies the voltage for an extremely short time. But because it moves enough, 10
A response speed of Hz or higher can be sufficiently secured.

[0021]

Embodiments of the present invention will be described below with reference to the drawings.

First, the structure will be described.

FIG. 1 is a sectional view showing a fluid pressure control valve of an embodiment of the present invention applied to an active hydraulic suspension.

As shown in FIG. 1, the fluid pressure control valve of the embodiment includes a valve hole 2 formed in a valve body 1 in a cylindrical shape,
A supply port 3, a return port 4 and a control port 5 which are formed in communication with the valve hole 2, and an axially movable arrangement in the valve hole 2 for switching the supply port 3 and the return port 4 to control port 5 6 that creates control pressure to the
And centering springs 7 and 8 arranged at both ends of the spool 6, and piezoelectric elements A, B and C provided on the spool 6.

The supply port 3 is connected to a hydraulic pressure source (not shown), the return port 4 is connected to a reserve tank (not shown), and the control port 5 is connected to a control pressure chamber of a damper unit (not shown). ..

Both ends of the spool 6 are supported by centering springs 7 and 8 which are preloaded so as to maintain a neutral position with respect to a small external force.

The piezoelectric elements A, B and C are formed by laminating a large number of single ceramic piezoelectric elements having electrodes formed on the front and back surfaces,
It is configured by electrically connecting individual ceramic piezoelectric elements in parallel. Among the piezoelectric elements A, B, and C, the piezoelectric element B is arranged in the axial direction such that the stacking direction of the single ceramic piezoelectric element coincides with the moving direction of the spool 6. C is a radial direction arrangement in which the stacking direction of the ceramic piezoelectric elements alone is perpendicular to the moving direction of the spool 6.

Both ends of the piezoelectric element B are adhered to the spool 6 with epoxy resin 9 or the like. A bolt 10 is provided at one end of each of the piezoelectric elements A and C, and a spool stopper 11 that is brought into pressure contact with the valve hole 2 is provided at the other end.

The element cords 12, 13 and 14 connected to the piezoelectric elements A, B and C are embedded in the seals 15 and 16 provided on the valve body 1 so that the spool 6 can follow the sliding movement. While the element code is 12, 1 to the outside
I try to pull out 3,14. The element codes 12, 13, 14 are connected to the output side of the piezoelectric element operation control circuit 17.

The piezoelectric element operation control circuit 17 receives the control pressure information from the control pressure sensor 18 and the target control pressure Pc * from the suspension controller 19.

The suspension controller 19 is
Control information is input from sensors and switches 20 necessary for controlling the lateral acceleration sensor, the longitudinal acceleration sensor, etc., and the target control pressure Pc * is calculated according to the information and the predetermined control content.

Next, the operation will be described.

(A) Piezoelectric element operation control FIG. 2 is a flow chart showing the flow of piezoelectric element operation control processing in the pressure increasing mode for increasing the control pressure performed by the piezoelectric element operation control circuit 17, and each step will be described below. ..

In step 100, the target control pressure Pc * is input from the suspension controller 19.

In step 110, a voltage is applied to the piezoelectric element C.

In step 121, a voltage is applied to the piezoelectric element B.

In step 122, a voltage is applied to the piezoelectric element A.

In step 123, the voltage of the piezoelectric element C is turned off.

In step 124, the voltage of the piezoelectric element B is turned off.

In step 125, a voltage is applied to the piezoelectric element C.

In step 126, the voltage of the piezoelectric element A is turned off.

At step 130, it is judged if the actual control pressure Pc from the control pressure sensor 18 is less than the target control pressure Pc *.

When it is judged as YES in step 130, the operation of the step 120 (step 120 to step 126) is repeated.

If NO at step 130,
Proceeding to step 140, the voltage of the piezoelectric element C is turned off.

(B) Piezoelectric element operation FIG. 3 shows step 110 and step 121 to step 1
FIG. 26 is an operation explanatory view showing the operation of the piezoelectric element in the pressure increasing mode corresponding to No. 26.

A voltage is applied to the piezoelectric element C to expand it (step 110). As a result, as shown in FIG. 3A, the piezoelectric element C is locked in the valve hole 2 and the movement of the spool 6 from the current position to the right is restricted.

Next, a voltage is applied to the piezoelectric element B to expand it (step 121). As a result, the spool 6 moves to the left as shown in FIG.

Next, a voltage is applied to the piezoelectric element A to expand it (step 122). As a result, as shown in FIG. 3C, the spool 6 is fixed at the position moved to the left.

Next, the voltage applied to the piezoelectric element C is cut off and shortened (step 123). As a result, FIG.
(D), the lock of the piezoelectric element C with respect to the valve hole 2 is released.

Next, the voltage applied to the piezoelectric element B is cut off and shortened (step 124). As a result, FIG.
As shown in (e), the piezoelectric element B moves leftward together with the piezoelectric element C.

Next, a voltage is applied to the piezoelectric element C to expand it (step 125). As a result, as shown in FIG. 3F, the piezoelectric element C is locked in the valve hole 2 and the movement of the spool 6 from the current position to the right is restricted.

Next, the voltage applied to the piezoelectric element A is cut off and shortened (step 126). As a result, FIG.
As shown in (g) of FIG. 3, only the spool 6 is moved to the left as a whole, and the state becomes exactly the same as the first state shown in (a) of FIG.

The spool 6 can be moved to the left by repeating the above-described operation of moving in a unit of a certain length, which is a so-called shakutai insect. In the decompression mode, spool 6
When moving the rightward, the left and right operations described above may be reversed.

Here, in order to obtain a response speed of 10 Hz or more, as shown in FIG. 4, when the target control pressure is changed,
A hydraulic response characteristic of 0.1 sec or less is required. Therefore, the routine from step 121 to step 130 must be performed within 0.1 sec. However, the number of times of this routine changes depending on the amount of expansion of the piezoelectric element B. That is, if the amount of extension is small, the number of routines is increased, and if the amount of extension is large, the number of routines is small. Specifically, the time required for one routine is 0.001s to move the piezoelectric element sufficiently.
ec and the amount of expansion of the piezoelectric element in one routine is 20 μm
Then, the number of routines is 100 times in 0.1 sec, and the spool movement amount is 2000 μm (2 mm).

Therefore, when applied to an active hydraulic suspension system, as shown by the dotted line characteristics in FIG.
A low response speed is set so that the damping force becomes large with respect to the movement (fluffy vibration) of the vehicle body in the sprung resonance frequency range around 10 Hz, and the vehicle body at the sprung-unsprung resonance frequency around 10 Hz is set. By setting the high response speed so that the damping force is small with respect to the movement (rough vibration), the vehicle body vibration level up to the unsprung resonance frequency range can be sufficiently reduced.

As described above, in the embodiment, in the fluid pressure control valve using the piezoelectric element as the actuator, the spool 6 has one set of piezoelectric element B in the axial direction and two sets of piezoelectric element A in the axially perpendicular direction. , C is interposed and the operation of repeating the operation of moving the spool itself in a unit of a fixed length by the expansion and contraction of the piezoelectric elements A, B, C is performed, so that the control response speed is increased and control response is required. It is possible to improve the control accuracy when performing.

Further, since the fluid pressure control valve is applied to the active hydraulic suspension system, it can respond to the required response speed from the unsprung resonance frequency range to the sprung resonance frequency range, and can be used together with damping force control by a damping valve or the like. Thus, it is possible to further improve the maneuverability and the riding comfort in a higher dimension.

Although the embodiments have been described with reference to the drawings, the fluid pressure control valve of the present invention is not limited to the application to the active hydraulic suspension system, and the responsiveness and the convergence are required. Can be applied to other hydraulic control systems.

[0059]

As described above, according to the present invention, in a fluid pressure control valve using a piezoelectric element as an actuator, at least one pair of piezoelectric elements is arranged on the spool and two pairs of piezoelectric elements are arranged vertically on the spool. However, since the spool itself is configured to be capable of repeating the operation of moving the spool in fixed length units by expansion and contraction of the piezoelectric element, the control response speed is increased to improve the control accuracy when control response is required. The effect that can be obtained is obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing a fluid pressure control valve according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a flow of a piezoelectric element operation control processing operation in a pressure increasing mode performed by a piezoelectric element operation control circuit of an embodiment control valve.

FIG. 3A to FIG. 3G are explanatory views showing a worm-like insect action by the piezoelectric element of the embodiment control valve.

FIG. 4 is a hydraulic response characteristic diagram when a target control pressure is increased at a high response speed.

FIG. 5 is a vehicle body vibration level characteristic diagram of an active hydraulic suspension system to which an embodiment control valve is applied.

[Explanation of symbols]

 1 Valve body 2 Valve hole 3 Supply port 4 Return port 5 Control port 6 Spool 7,8 Centering spring A, B, C Piezoelectric element

Claims (1)

[Claims] 1. A supply port, a return port, and a control port formed in a valve hole, and a spool disposed in the valve hole so as to be movable in the axial direction, and switching the supply port and the return port to generate a control pressure to the control port. And a piezoelectric element having at least one set interposed in the axial direction of the spool and two sets interposed in the direction perpendicular to the axis.