JPH0314982A - Driver for liquid pressure changeover valve - Google Patents

Abstract

PURPOSE:To control the movement of valve body with high accuracy by elongating a piezoelectric lamination body with a first drive voltage and a second drive voltage higher than the former, in a fuel injection valve, and seating the valve body on a valve seat through a displacement transmission mechanism. CONSTITUTION:When a ECU applies time for fuel injection and a first drive voltage to a piezoelectric lamination body 11, the body 11 is elongated to push a piston against a spring 14 and a valve body 16 is moved in a close manner to a valve seat 18. A second drive voltage higher than the first voltage is then applied, so that the body 16 is pushed to the seat 18 strongly to close a fluid passage 192 and pressure-feeds fluid from a liquid pressure-feeding unit 20 to a liquid pressure working element 22 through a fluid passage 191. After the lapse of injection time, the application of first and second drive voltages is released, and the body 16 is separated from the seat 18 by returning the piston 12 with the spring 14. It is thus possible to perform fuel injection control and the like with high accuracy.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is effectively used, for example, as a drive control means for a fuel injection valve of a diesel engine, and can be used to control a range from a very small amount of fuel injection to a maximum injection amount. , relates to a drive device for a hydraulic switching valve that enables accurate electronic control.

[Prior Art] A pressure sensor constructed by laminating multiple thin plate piezoelectric elements. I!
For example, a hydraulic switching valve constructed using a laminate and used to construct a fuel injection device, for example,
A unit injector disclosed in Japanese Patent No. 1-187965 is known. In this injector, a control valve is arranged so as to be driven by an actuator formed of a piezoelectric laminate, and by controlling the opening/closing timing of this control valve, the fuel injection timing and injection amount can be controlled. I'm trying to get it done.

That is, the fuel injection timing is set by the application timing of the voltage applied to the piezoelectric laminate, and the amount of injected fuel is controlled by the voltage application time width.

FIG. 14(A) shows an example of a drive voltage that is controlled to be applied to the actuator made of the piezoelectric laminate, and this drive voltage is composed of a rectangular pulse with a pulse width TI corresponding to the fuel injection time width. Ru. The voltage E of this square pulse
l is set to a voltage value sufficient to drive the valve element that opens and closes the fuel passage and firmly contacts the valve seat.

However, if such a driving voltage is used to control the expansion of the piezoelectric laminate to drive the valve element in the fuel passage, when the valve element is seated on the valve seat, the valve element will not move relative to the valve seat. It collides violently and starts bouncing. If the set fuel injection amount is very small and the pulse width of the driving voltage is in a very narrow region as shown by a and b in FIG. 14(A), As shown by a and b in FIG. 1, due to the effect of the bounce of the valve body, a reversal phenomenon occurs between the driving voltage pulse width and the time during which the valve body is displaced. Therefore, the fuel injection amount, which is proportional to the valve body displacement time, and the drive voltage pulse width are reversed, and there is a discontinuity between the injection amount and the drive voltage pulse width, as shown in FIG. As a result, a pulsation phenomenon occurs in the injected fuel pressure, making it difficult to improve the accuracy especially when controlling the injection of a small amount of fuel.

[Problems to be Solved by the Invention] The present invention has been made in view of the above points, and is capable of reliably reducing pressure pulsation caused by bounce of a controlled valve body, for example, in a diesel engine fuel injection system. Controlling the maximum injection amount in diesel engines with a wide drive pulse width from the control range of minute injection amount rB
The present invention aims to provide a driving device for a hydraulic pressure switching valve that can be electronically controlled with high precision up to the nR range.

[Means for Solving the Problems] A driving device for a pressure switching valve according to the present invention includes a piezoelectric laminate whose expansion and contraction are controlled by an applied voltage, and drives a valve body by the expansion and contraction of the piezoelectric laminate. In the device in which the valve body is selectively brought into contact with the valve seat to open and close the liquid flow passage, a first drive that lengthens the piezoelectric laminate and moves the valve body toward the valve seat. generating a voltage, followed by a second drive voltage higher than the first drive voltage;
first and second drive voltage generating means for generating drive voltages are provided, and the drive means includes means for arbitrarily and variably setting application setting time widths of the first and second drive voltages. It was to so.

[Function] According to the drive device for the hydraulic pressure switching valve configured as described above, by applying the first drive voltage to the piezoelectric laminate, the valve body is driven to a position sufficiently close to the valve seat, and the first drive voltage is applied to the piezoelectric layered body. By applying the drive voltage No. 2, the valve body is brought into firm contact with the valve seat. By controlling the drive of the valve body in this manner, the valve body is prevented from colliding with the valve seat and bouncing, and the occurrence of hydraulic pressure pulsation is prevented. In addition, when applying it to a fuel injection valve and setting the injection amount to a very small amount, by shortening the application time width of the first driving voltage and shortening the application time of the second driving voltage, it is possible to reduce the injection amount to a very small amount. The injection amount can be set and controlled with high precision, and if you want to increase the injection amount, you only need to widen the application time range of the second drive voltage, and the injection amount can be precisely controlled from the minute injection amount to the maximum injection amount. It becomes like this.

[Embodiments of the invention] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

Figure 1 shows the configuration of 10 parts of the hydraulic pressure switching valve mechanism.
A piezoelectric laminate 11 configured by laminating a plurality of disc-shaped piezoelectric elements is provided. This piezoelectric laminate {] consists of disc-shaped piezoelectric elements stacked one after another with electrode layers interposed between them, and a voltage is applied and controlled in parallel to each piezoelectric element. By doing so, the laminate 11 is expanded by an amount corresponding to the voltage value.

This piezoelectric laminate l1 is housed inside a piston 12 having a cylindrical shape with a bottom, and the piston 12 is set to be movable in the axial direction within a cylinder 13. An oil-tight chamber 131 is formed inside the cylinder l3 so as to be partitioned by the bottom surface of the piston 12, and the piezoelectric laminate I1 is set to protrude from the open end surface of the piston l2.
It is made to come into contact with the wall surface on the opposite side from 1. In this case, the piston 12 is set to be pressed by a spring 14 in the direction of the wall surface against which the piezoelectric laminate 1l comes into contact.
When the piezoelectric laminate 11 is expanded, the piston l2 is moved against the spring l4 in a direction that reduces the volume of the oil-tight chamber 131.

The oil-tight passage 15 is communicated with the oil-tight chamber 131, and a valve body 16 is set in the oil-tight passage 15. The valve body l6 is urged toward the oil-tight chamber 131 by a spring l7, and when the piston 12 is moved against the spring l4 and the pressure inside the oil-tight chamber 131 is increased, the valve body l6 is biased toward the oil-tight chamber 131.
6 is moved against the spring 17 and is brought into pressure contact with the valve seat l8.

Here, the cross-sectional area of the valve body l6 is set smaller than the cross-sectional area of the oil-tight chamber 131 in the cylinder 13, and the amount of movement (displacement amount) of the piston 12 corresponding to the amount of displacement of the piezoelectric laminate 11 is , the valve body i
6.

This valve body l6 is set at the intersection of the fluid passages 191 and 192, and when the valve body 16 comes into contact with the valve seat l8, the gap between the fluid passages 191 and 192 is cut off, and the valve body When l6 separates from valve seat I8, fluid passages 191 and 192 are communicated with each other.

Liquid from the reservoir 21, such as fuel in the case of a fuel injection device, is pumped and supplied to the fluid passage 191 by the liquid pumping device 20.
A hydraulically actuated element 22, such as a fuel injection valve, is connected to the fuel injection valve 1. Further, the fluid passage 192 is communicated with the reservoir 21, and the liquid discharged from this passage 192 is transferred to the reservoir 21.
so that it can be attributed to

23 is an engine control unit (ECU), for example;
The ECU 23 calculates engine control information such as a fuel injection amount suitable for the engine operating conditions based on detection signals from various sensors, and executes electronic control of the engine.

A drive circuit 24 is controlled based on the calculation result of the fuel injection amount in the ECU 23, and the drive circuit 24 generates a voltage to be applied to the piezoelectric laminate U to control the expansion of the laminate 11.

In the hydraulic switching valve mechanism lO configured as described above, when no voltage is applied to the piezoelectric laminate I1,
This piezoelectric laminate l1 is in a contracted state, and the valve element i6 is set away from the valve seat 18 by a spring l7. Therefore, the liquid such as fuel, which is pumped by the liquid pumping device 20, is transferred from the fluid passage 191 to the fluid passage 1.
92 and is returned to the reservoir 21 and is not supplied to the hydraulically actuated element 22. This hydraulically actuated element 22
However, if the injector is a fuel injection valve of a diesel engine, for example, no fuel is injected from the injector.

When a voltage is applied to the piezoelectric laminate l1 from the drive circuit 24, the piezoelectric laminate 11 expands and the piston l2
is displaced, the valve element I6 is driven against the spring 17, and is brought into contact with the valve seat l8. Therefore, fluid passage 191
and 192, and the liquid, e.g. fuel, pumped by the liquid pumping device 20 is pumped to the hydraulically actuated element 22, and if this element 22 is, for example, a fuel injection valve of a diesel engine, this Fuel is injected from the injection valve. That is, the operation of the hydraulic actuation element 22 is controlled by the expansion and contraction operation of the piezoelectric laminate U, and, for example, fuel injection control in a fuel injection valve is executed. Then, the fuel injection amount is set and controlled by the voltage application time width to the piezoelectric laminate ti.

(A) in each of FIGS. 2 and 3 shows the state of the drive voltage applied to the piezoelectric laminate 11 from the drive circuit 24 when this hydraulic switching valve mechanism 10 is applied to a fuel injection valve of a diesel engine. It shows. First, a first driving voltage EO is generated to move the valve body l6 to a position approaching the valve seat l8. Thereafter, a second driving voltage El higher than the first voltage EO is generated, and the valve element l6 is moved to the valve seat 1.
8 to block the fluid passages 191 and 192, and the liquid pumped by the liquid pumping device 20
so that the hydraulically actuated element 22 is supplied.

Here, FIG. 2 shows a case where the amount of injected fuel is in a very small area, and as shown by the broken line in (A) of the same figure, the period during which the second driving voltage El is applied and set. T2 is kept constant, and the period TO during which the first drive voltage EO is applied is variably controlled. When varied in this manner, the state of the hydraulic pressure applied to the hydraulic pressure operating element 22, that is, the fuel injection amount, becomes as shown in (B) of the figure.

Also, Figure 3 shows the case where the fuel injection amount is set to a large amount,
As shown in (A) of the same figure, the period TO in which the first drive voltage EO is applied is constant, and the period T2 in which the second voltage El is applied is changed, as shown in (B) in the same figure. ensure that appropriate fuel injection characteristics are obtained.

FIG. 4 explains means for generating a drive voltage applied to such a piezoelectric laminate 1l, and this drive voltage generation control is performed in the ECU 23.

First, in the fuel injection amount calculation means 3l, the ECU 2
Based on detection signals from sensors such as engine speed, intake air amount, throttle opening, cooling water temperature, air-fuel ratio, etc. supplied to 3, calculates the appropriate fuel injection amount in accordance with the engine operating status at that time. do. Then, corresponding to the calculated fuel injection amount, the time width calculating means 32 and 33 calculate the time width TO of the first drive voltage and the time width T2 of the second drive voltage. In this case, the rise of the time width of the second drive voltage is set after the time width TO of the first drive voltage has elapsed.

Then, the first drive voltage generating means 34 generates a first drive voltage of voltage EO during the calculated first drive voltage time width TO. Further, the second driving voltage generating means 35
During the calculated second driving voltage time width T2,
A second drive voltage of voltage El is generated. The first and second drive voltages generated in this manner are applied to the piezoelectric laminate 11.

FIG. 5 shows an outline of the drive control means when the switching valve mechanism 10 shown in FIG. 1 is applied to a fuel injection device of a diesel engine. The hydraulically actuated element 22 corresponds to the injection nozzle 42. In addition, analog detection is performed from an intake pressure sensor 43 that detects the intake air pressure of the intake manifold, a water temperature sensor 44 set inside the water jacket of the cylinder block, and an accelerator (throttle) opening sensor 45 that is linked to the accelerator pedal. The signal is sent to the A/D converter 4 of the electronic control circuit 46.
Supply to 7. Furthermore, an input/output interface 48 of this electronic control circuit 46 includes an engine crank angle sensor 4.
Output signals from sensors 9 are supplied, and human input signals from these sensors are made to act on the CPU 50 as interrupt signals.

The electronic control circuit 46 is configured as a microcomputer, for example, and includes an A/D converter 47, a human output interface 48, a CPU 50, etc., as well as a timer 51, a ROM 52 that stores programs, etc., temporary data, etc. A RAM 53 for storing the information, a thyristor firing circuit 54 for controlling the drive circuit 24, and the like are set.

That is, the application time width TO of the first drive voltage EO and the injection time width T1 are set in the timer 51. Also,
This timer 51 tells the CPU 50 to
An injection timing interrupt signal and an application end interrupt signal of the first drive voltage EO are generated after the time width TO has elapsed.

FIG. 6 shows a specific example of the thyristor ignition circuit 54. This ignition circuit 54 is supplied with a drive signal consisting of rectangular pulses Sl and S2 corresponding to the application time TO of the first drive voltage EO and the injection time Tl. These square pulses SL and S2 are generated by the intake pressure sensor 43 shown in FIG.
, the application time width TO of the first drive voltage EO and the injection time TI are expressed by the injection timing calculated based on the detection signals from the water temperature sensor 44, the accelerator opening sensor 45, and the crank angle sensor 49, respectively. There is.

The drive signal S1 is transmitted through the first and second one-siggot circuits 5
5 and 56, and the drive signal s2 is supplied to a third one-shot circuit 57. Here, the first one-shot circuit 55 generates a pulse signal with a constant time width at the rising edge of the square pulse SL, and the second one-shot circuit 56 generates a pulse signal with a constant time width at the falling edge of the square pulse SL. occurs. Then, the third one-shot circuit 57 generates a pulse signal with a constant time width at the falling edge of the rectangular pulse S2.

Such first to third one-shot circuits 55 to 57
The pulse signals outputted from each are sent to gate drive circuits 58 to 60 each constituted by a pulse transformer.
and the first to third gate drive signals PI-P3 are outputted from each of these gate drive circuits 58 to 60. The gate drive circuits 58 to 60 electrically insulate the gate circuits of separate thyristors by means of a valve transformer.

FIG. 7 shows a drive circuit 24 that generates a high voltage for driving the piezoelectric laminate 11. Power from a battery power source 6l is supplied to a DC-DC converter 62, and this converter 62 and form second base voltages EO' and El'.

Here, "El'>EO'", for example, "EO"
-300V'"El" is set to -500V.

The base voltage EO' is set to be applied to the piezoelectric laminate l1 via the first thyristor 63 and the coil 64, and the base voltage El' is set to be applied to the piezoelectric laminate l1 via the first thyristor 63 and the coil 64.
5 and the coil 66 to apply it to the piezoelectric laminate 11 . Further, a series circuit of a third thyristor 67 and a coil 68 is connected in parallel to the piezoelectric laminate 11 . And the first to third thyristors 63,
Outputs P1 to P3 obtained from the ignition circuit 54 are respectively supplied to 65 and 67 as gate signals.

That is, the drive pulse p from the Cyrisk ignition circuit 54
When the thyristor 63 is fired by t, the voltage EO'
Due to the LC resonance between the coil 64 and the piezoelectric laminate 1l, the first driving voltage EO is set to be applied to the piezoelectric laminate 11 as shown in FIG.

Then, after the time TO has elapsed, the thyristor 65 is fired by the drive signal P2 which is the output from the gate drive circuit 59, and the piezoelectric laminate is The voltage applied to the body 11 increases by E2 shown in FIG. 2, and becomes the second driving voltage El.

Then, the injection time TI after the thyristor 63 is ignited
After the lapse of , the thyristor 67 is fired by the drive signal P3 from the gate drive circuit GO, and due to the LC resonance between the coil 68 and the piezoelectric laminate 11, the voltage set to be applied to the piezoelectric laminate 11 becomes "O". disappears.

FIG. 8 is a timing chart illustrating the operating states of the thyristor ignition circuit 54 shown in FIG. 6 and the drive circuit 24 shown in FIG. 7.

9 to 12 are flowcharts illustrating the operating state of the electronic control circuit 46. FIG. That is, FIG. 9 shows the main routine, which is initialized in step 101. For example, the injection period data etc. stored in the RAM 53 are initialized, and the timer 51 and the input/output interface 48 are initialized. Once initialized in this way, each sensor 43 to
Detection signals from 45, 49, etc. are suitably A/D converted and taken in, and in step 103, the injection timing, drive voltage application interval TO, injection period Tl, etc. are calculated, and in step 104, the 1 driving voltage E
O application time TO, injection timing, and injection period T
1 is set in the timer 51.

In the timer 5l, a square pulse signal Sl that is counted based on the reference signal and angle signal input from the crank angle sensor 49 and sets the application time TO of the first drive voltage EO, and a square pulse signal that expresses the injection period T1 are counted. S2 is output to the human output interface 48, and also generates the timing of the first drive voltage end interrupt and the injection end interrupt. Here, when the electronic control circuit 4B is first activated, the timer 51 is set in step 101 of the main routine.

Then, the timer 51 is set in this way, and when the timer 51 times up, the CPU 50
An interrupt occurs.

10 to 12 show an interrupt routine for injection timing, termination of the first drive voltage, and termination of injection, which is executed when the timer 51 times up.

First, in the injection timing interrupt routine shown in FIG. 10, in step 111, the square pulse signal S1 corresponding to the first drive voltage is turned on from off, and the square pulse signal S2 for the injection period is turned on from off,
Step 112 ends this interrupt routine.

In the first drive voltage end interrupt routine for ending the first drive voltage shown in FIG. 11, in step 121, the square pulse signal SL of the first drive voltage is switched from on to off;
Step 122 ends this interrupt routine.

In the injection period end interrupt routine shown in FIG. 12, the injection period rectangular pulse signal S2 is turned from on to off in step 131, and this interrupt routine is ended in step 131.

The driving voltage VD shown in FIG. 8 is obtained by applying the voltage El (
-EO+E2) is applied, and the time TL is applied from the start of voltage application.
A two-stage voltage waveform is constructed in which the voltage disappears after . When such a voltage signal is applied to the piezoelectric laminate l1, the first drive voltage EO causes the piezoelectric laminate l1 to
becomes longer and the valve body 16 moves downward. During this movement, the moving speed of the valve body 16 is reduced by the elastic repulsive force of the spring 17, the sliding resistance of the valve body 16, and the like.

For this reason, the voltage EO is set to a voltage value such that the valve body 16 starts moving and stops near the valve seat 18 after a time TO has elapsed. In this way, the first drive voltage EO
When the second drive voltage E1 is set to be applied after a time TO has elapsed from the start of application of the valve element l6, the valve element l6 stops near the valve seat 18 and then comes into complete contact with the valve seat 18. , communication between the passages 191 and 192 is cut off.

Here, the second drive voltage El is a voltage that enables sufficient hydraulic pressure to be generated in the oil-tight passage 15 so that the valve body 16 is brought into close contact with the valve seat 18.

In this way, the voltages EO, E2 and the voltage application time TO,
If T2 is set, the valve body l6 will be connected to the valve seat 1.
It is temporarily stopped near the oil-tight chamber 15, so that it will not bounce due to the pressure from the oil-tight chamber 15.

Here, the first drive voltage EO and the voltage application time width TO
is a value that is almost uniquely determined by the moving distance and mass of the valve element 16, as well as the biasing force of the spring 17. Therefore, there is no need to perform variable control depending on environmental conditions and the like. However, if it is necessary to operate precisely, the electronic control circuit 46 may be used to make corrections based on the output signals from each sensor.

Next, the valve body 16 of the switching valve mechanism 10 configured in this manner
The principle of operation control will be explained. Region B shown in FIG. 13 is where a relatively large fuel injection amount is set;
When it is necessary to control the injection amount in this region, as shown in FIG. E1
The movement of the valve body l6 is controlled by varying the application time width T2. By controlling in this manner, the time period during which the valve body l6 is seated on the valve seat l8 can be varied,
Therefore, the reciprocating time of the movement of the valve body 16 can be freely and variably controlled by electronic control.

If such control is executed, the above-mentioned result will be achieved. Valve body 1 as shown
6 collides with the valve seat 18 and bounces, so the relationship between the injection amount and the voltage pulse width applied to the piezoelectric laminate 11 is as shown in FIG. 3 (B). The relationship changes linearly. Therefore, the valve body l
8 also reduces pressure pulsations within the passage 191, allowing electronic control of the injection amount to be executed with high precision.

On the other hand, in a region where a small amount of injection amount is controlled such as region A shown in FIG. 13, the time width T2 for applying the second drive voltage E2 is fixed as shown in FIG. 2 (A). The movement of the valve body 16 is controlled by variably controlling the time TO during which the first drive voltage EO is applied.

With such a control mode, the seating speed of the valve body 16 on the valve seat l8 changes, and the reciprocating time of the valve body 16 can be freely electronically controlled.

That is, the shorter the application time of the first drive voltage EO, the earlier the second drive voltage El will be applied after the valve body 16 starts moving, and therefore the valve seat l8 of the valve body l6 will be applied. The seating speed increases. Therefore, the valve body 16 violently collides with the valve seat 18 and bounces significantly, making it possible to reciprocate the valve body 16 very quickly.

In this case, in order to achieve higher responsiveness, it is desirable to set the application time width of the second drive voltage E1 as short as possible. However, control is possible during the time period from when the valve body 16 bounces onto the valve seat 18 and once separates from the valve seat 18 until it seats on the valve seat 18 again.

Therefore, if this hydraulic pressure switching valve mechanism is applied to a diesel engine fuel injection system, it will be possible to electronically control the injection amount from a minute injection amount to a maximum injection amount with high accuracy without impairing the proportional relationship. .

In the embodiment, the liquid pumping device 20 may be a vane bomb, a piston pump, or a radial plunger bomb driven by an electric motor. Further, the hydraulic actuating element 22 may be an actuator that operates at high speed, such as a power piston that operates a brake pad of a brake device.

For example, if this device is applied to a vehicle brake system, a radial plunger pump will be used as the hydraulic pressure feeding device 20, a power piston will be used as the hydraulic actuation element 22, and the electronic control circuit 46 will be manually operated. The sensor signals include detection signals such as water temperature, accelerator opening, brake pedal force, and vehicle speed. Then, based on these detection signals, the force, timing, time, etc. for applying the brake may be calculated, and the calculation results may be output to the drive circuit 24.

[Effects of the Invention] As described above, according to the drive device for the branch pressure switching valve according to the present invention, the movement of the valve body can be controlled with high precision, and the control can be performed with high precision, especially when the valve opening time is short. It is something that can easily be made highly accurate, for example when configuring a fuel injection device for a diesel engine,
Injection amount control can be executed with high precision from a very small amount of injected fuel to a maximum injection amount. Therefore, it can be effectively applied to various hydraulic control systems.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram illustrating a hydraulic switching valve mechanism according to an embodiment of the present invention, and FIGS. 2 and 3 respectively show the driving voltage applied to the piezoelectric laminate constituting the above device and the voltage of the valve body. Figure 4 is a diagram showing the state of movement, Figure 4 is a configuration diagram illustrating drive voltage generation control means for the piezoelectric laminate, Figure 5 is a configuration diagram illustrating control means for the switching valve mechanism, and Figure 6 is a diagram illustrating this control. FIG. 7 is a block diagram showing the thyristor ignition circuit in the control means, FIG. 7 is a block diagram showing the drive circuit, FIG. 8 is a time chart, and FIGS. 9 to 12 are flow charts for explaining the operation of the control means. , FIG. 13 is a diagram showing the control region in the fuel injection device, FIG. 14 is a diagram explaining the state of drive voltage and valve body displacement in a conventional switching valve mechanism, and FIG. 15 is a diagram showing the drive pulse width and injection amount. FIG. 10... Switching valve mechanism, 11... Piezoelectric laminate, 12
... Piston, 131... Oil-tight chamber, 15... Oil-tight passage, 1B... Valve body, l7... Spring, 18...
...Valve seat, 191, 192...Fluid passage, 20...
・Liquid pressure feeding device, 22... Branch pressure actuation element, 23...
ECU, 24... Drive circuit.

Claims (1)

[Claims] A piezoelectric laminate formed by laminating piezoelectric elements whose expansion and contraction are controlled by controlling the application of a voltage, and which magnifies and transmits the displacement amount of the expansion and contraction of the piezoelectric laminate. A displacement transmission mechanism, a passage through which liquid flows, a valve seat set in the middle of this passage, and a valve seat that is seated on the valve seat due to the operation of the displacement transmission mechanism that is displaced as the piezoelectric laminate expands. a first drive voltage that generates a first drive voltage that extends the piezoelectric laminate to a first state so as to move the valve body toward the valve seat; generating means; and second driving voltage generating means for generating a second driving voltage higher than the first driving voltage, wherein the first and second driving voltage generating means each have a second driving voltage higher than the first driving voltage. and means for arbitrarily variably setting the application set time width of the second drive voltage.