JPH01269767A - Driving device for fluid pressure selector valve - Google Patents

Abstract

PURPOSE:To reduce the bound of a valve body by adding the first driving voltage for shifting the valve body to the neighborhood of a valve seat, and then adding further higher the secondary driving voltage to a piezoelectric laminated body. CONSTITUTION:A piezoelectric laminated body (PZT2) is added by driving voltage to be extended by the first driving voltage E1 for moving a valve body 6. But the movement of the valve body is reduced by the reaction force of a spring 7 or the sliding resistance of the valve body itself and is stopped in a short time. A time from the beginning of the movement of the valve body to its stoppage is a time To and the valve body 6 is positioned near a valve seat 8. At this time, further driving voltage E2 is added to PZT2 to tightly close the valve body 6 to the valve seat so as to generate enough oil pressure in an oiltight chamber 5 to shut off the communication to a passage 13b.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a drive device that drives a hydraulic switching valve at high speed using a piezoelectric laminate.

[Conventional technology]

An example of a unit injector that uses a piezoelectric laminate (PZT) to drive a hydraulic pressure switching valve and control hydraulic pressure is disclosed in Japanese Utility Model Application Publication No. 187965/1983.

In this unit injector, a pressure chamber serving as a fuel pressure feeding section is formed within the injector main body, and this pressure chamber communicates with a fuel supply passage and a fuel discharge passage. A control valve driven by a piezoelectric element actuator is arranged in the fuel discharge passage, and the fuel discharge passage is opened and closed by this control valve.

Therefore, with the piezoelectric element actuator and the control valve,
The pressure of the fuel within the pressure chamber is controlled. This makes it possible to control the timing and amount of fuel injected from the fuel injection nozzle communicating with the pressure chamber. Conventionally, a piezoelectric element actuator has been applied with a drive voltage consisting of a simple square pulse as shown by the dotted line in FIG. 2(a).

[Problems to be Solved by the Invention] However, when the above driving voltage is applied, the speed of the valve element of the control valve reaches its maximum when it seats on the valve seat.
The valve body collides with the valve seat and bounces.

This state is shown by the dotted line in FIG. 2Cb). For this reason, the fuel in the pressure chamber contains severe vibrations and pulsations,
This may cause problems such as a decrease in the function and durability of the injector.

The present invention has been made in view of the above points, and provides a driving device for a hydraulic pressure switching valve that can reduce vibrations and pulsations of the liquid controlled by the valve body by reducing bounce of the valve body. The purpose is to

[Means to solve the problem]

Therefore, a driving device for a hydraulic switching valve according to the present invention includes a piezoelectric laminate, a transmission means for transmitting an enlarged displacement of the piezoelectric laminate, a passage through which liquid flows, and a valve seat provided in the middle of the passage. and a valve body that is displaced in response to the displacement of the piezoelectric body 411 that is transmitted by the transmission means through expansion, and that seats on the valve seat to shut off communication with the passage; driving means for applying a first driving voltage to the piezoelectric laminate to move it near the seat, and then applying a second driving voltage higher than the first driving voltage to the piezoelectric laminate; The structure is as follows.

(Operation) According to the above configuration, when seating the valve body on the valve seat,
The driving means first applies a first driving voltage to the piezoelectric stone stack. Here, the first drive voltage is set to a magnitude that moves the valve body close to the valve seat. Therefore, the valve body does not collide with the valve seat and bounce. Next, the driving means applies a second driving voltage higher than the first driving voltage to the piezoelectric laminate. As a result, the valve body is seated on the valve seat, and communication between the passages is cut off.

[Effects of the Invention] As described above, according to the present invention, bouncing when the valve body seats on the valve seat can be reduced, and therefore vibrations and pulsations of the liquid controlled by the valve body can be reduced. can.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

The hydraulic switching valve 1 is a valve that closes a passage 13b by seating a piezoelectric laminate (PZT) 2, a spring 3, a driving piston 4, an oil field chamber 5 as a transmission means, a valve body 6, a spring 7, and a valve body 6. Consists of 8 seats. When a driving voltage is applied to the PZT2 and it expands, the driving piston 4 containing the PZT2 moves toward the oil-tight chamber 5. Since the cross-sectional area of the drive piston 4 is larger than the cross-sectional area of the valve body 6, the amount of displacement of the drive piston 4, that is, the PZT2, is expanded by the oil-tight chamber 5 and transmitted to the valve body 6. At that time, the valve body 6 moves in the direction of the valve seat 8 against the biasing force of the spring 7.
sit down. When the driving voltage of PZT2 disappears and PZT2 contracts, the driving piston 4 moves in the opposite direction to the oil-tight chamber 5 due to the biasing force of the spring 3. Then, the valve body 6
is moved toward the oil-tight chamber and separated from the valve seat 8 by the biasing force of the spring 7.

The hydraulic switching valve 1 that operates as described above is located in the middle of the passage 13b that allows the liquid to flow back to the reservoir 14 from the passage 13a that communicates the liquid pressure-feeding device 9 that pumps liquid from the reservoir 14 with the hydraulic actuation element 10. Placed.

Further, the PZT 2 is connected to a driving device 11 as a driving means, and the driving device 11 applies a driving voltage to the PZT 2 based on a signal from an electronic control circuit (ECU) 12.

Here, circuit diagrams of the drive device 11 are shown in FIGS. 3 and 4.

Based on the signals from each sensor, the ECU 12 calculates the time T1 and its timing for driving the PZT2, and
Outputs a drive signal (square pulse) to the

This drive signal is a one-shot (0/5) shown in Figure 3.
-1 circuit 21, delay circuit 22, and O/S-3 circuit 23 are manually operated. The O/S-1 circuit 21 generates one pulse at the rising edge of the square pulse. The delay circuit 22 delays the rise timing of the rectangular pulse by T0 time, and outputs O/
It is output to the S-2 circuit 24. The O/S-2 circuit 24 also
Similar to the S-1 circuit 21, one pulse is generated at the rising edge of the square pulse. On the other hand, 0/S-3 circuit 2
No. 3 generates one pulse at the falling edge of the square pulse. Pulses output from the respective O/S circuits 21, 23, and 24 are input to gate drive circuits (pulse transformers) 25, 26, and 27, respectively. Gate drive circuit 2
5, 26, and 27 are for applying driving pulses to the gates of thyristors 30, 31, and 32, and each 0/S circuit 2
Pulse signals from 1.23.24 are amplified without grounding, and impedance matching is performed for the gates of Cyrisk 30 and 31.32.

FIG. 4 shows a circuit that generates a high voltage for driving PZT2.

In FIG. 4, the first and second pace voltages E,',
Eo' is created. Here, EO'>El', for example, E,'-150(v), E,'-500(
V). When the thyristor 30 is turned on by the drive pulse from the gate drive circuit 25, the LC resonance between the coil 33 and the PZT2 due to the voltage El' causes the thyristor 30 to turn on as shown in FIG.
), the first drive voltage E1 is applied to PZT2. Furthermore, after time T0, the thyristor 31 is turned on by the gate drive circuit 26, and the voltage (E,'-E,'
) due to the LC resonance of the coil 34 and PZT2,
The voltage applied to PZT2 is E as shown in Figure 2(a).
2 to become the second drive voltage E0. thyristor 30
When the thyristor 32 is turned on by the gate drive circuit 27 after T+ time after it is turned on, the coil 35 and the PZ
Due to the LC resonance of T2, the voltage applied to PZT2 becomes zero.

Here, the delay time T0 by the delay circuit 22 is the time required for the valve body 6 to move close enough to sit on the valve seat 8, and the delay time T0 is the distance the valve body 6 moves, 14] and the attachment of the spring 6. It is a time that is uniquely determined by the power. Therefore, it is not necessary to make the delay time T0 variable depending on environmental conditions and the like.

However, when strict operation is required, the ECU 12 has a function equivalent to a delay circuit instead of the delay circuit 22 and outputs a rectangular pulse to the O/S-1 circuit 21.
After 0 hours, the O/S-2 circuit 2 is activated by the ECU 12 itself.
4, the delay time T is configured to output a rectangular pulse. You may also correct it.

The second
When the drive voltage shown in Figure (a) is applied to the PZT2, the PZT2 expands due to the first drive voltage E1, and the valve body 6 moves. However, due to the reaction force of the spring 7 and the sliding resistance of the valve body 6 itself, it is decelerated as shown in FIG. 2(C) and eventually stops. The time from when the valve body 6 starts moving until it stops is T0 time, and the valve body 6 is located near the valve seat 8 after the T0 time. At this time, a driving voltage E2 (=E, -E,) is further applied to PZT2 to generate sufficient hydraulic pressure in the oil-tight chamber 5 to bring the valve body 6 into close contact with the valve seat 8 and cut off communication with the passage 13b. let Since the valve body 6 is almost at the seated position in the stopped state, it does not bounce (seats on the valve seat 8) even if it receives a force from the oil-tight chamber 5, as shown in FIG. 2 (co).

Note that the liquid pressure feeding device 9 is a general pressure feeding means, such as a vane pump or a piston pump. Further, a jerk type plunger pump used in a diesel engine may be used, or a radial plunger pump driven by an electric motor may be used.

Further, the hydraulic actuating element 10 is an actuator that operates at high speed, such as a power piston that operates a brake pad of a brake device, an automatic valve (injection nozzle) of a diesel engine, or the like.

For example, if the present invention is applied to a brake system, a radial plunger pump would serve as the liquid pumping device 9, and a power piston would serve as the hydraulic actuating element 10.
Signals from sensors input to the ECU 12 include accelerator opening, water temperature, brake pedal force, vehicle speed, and the like. From these signals, the ECU 12 calculates the timing and time to apply the brakes, and outputs a signal to the drive device 11.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing the configuration of an embodiment of the present invention, FIG. 2(a) is a driving voltage waveform diagram of PZT in FIG. 1, and FIG. 2(b)
), (C) are explanatory diagrams for explaining the operation of the spill valve in FIG. 1, and FIGS. 3 and 4 are circuit diagrams for generating the driving voltage waveform shown in FIG. 2(a). 2... Piezoelectric laminate (PZT), 5... Oil-tight chamber, 6...
... Spill valve, 8 ... Valve seat, 11 ... Drive device, 1
2...ECU, 13...Aisle.

Claims (1)

[Scope of Claims] A piezoelectric laminate, a transmission means for magnifying and transmitting the amount of displacement of the piezoelectric laminate, a passage through which liquid flows, a valve seat provided in the middle of the passage, and the transmission means a valve body that is displaced in response to an amount of displacement of the piezoelectric laminate that is expanded and transmitted, and seats on the valve seat to block communication with the passage; and a valve body that is moved to the vicinity of the valve seat. a driving means for applying a first driving voltage to the piezoelectric laminate, and then applying a second driving voltage higher than the first driving voltage to the piezoelectric laminate; Drive device for pressure switching valve.