JPS62131942A - Fuel injection device - Google Patents

Abstract

PURPOSE:To enhance the responsive characteristic of a fuel injection device to reduce the fuel consumption thereof, by providing a switching means for turning on and off piezoelectric elements adapted to open and close a fuel injection valve and a replenishing circuit for replenishing electrical power. CONSTITUTION:In a fuel injection valve 8, there are provided a first piezoelectric element 90 for driving the fuel injection valve 8 in its opening direction and a second piezoelectric element 91 for driving the same in its closing direction. An electronic control device 30 controls the output of a Diesel engine by means of a fuel injection valve drive device 40 and a pump drive device in accordance with the outputs of several sensors. A drive voltage generating circuit 120 raises the voltage of a battery which is therefore fed to the fuel injection valve drive device 40. Thus, the responsive characteristic of the fuel injection valve is enhanced, thereby it is possible to reduce the electrical power consumption thereof.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a fuel injection device, and more specifically, to a fuel injection valve incorporating two piezoelectric elements that drive the opening and closing of a valve body, and the piezoelectric The present invention relates to a fuel injection device including a drive circuit that drives a piezoelectric element.

[Prior Art] Conventionally, fuel injection valves have been known that focus on the high responsiveness of the elongation action of a piezoelectric element and use the piezoelectric element as an actuator to open and close the valve (for example, Japanese Patent Laid-Open No. 58-21
``Fuel injection device'' of Publication No. 0357). In this type of fuel injection device, when injecting fuel, a voltage is applied to the piezoelectric element to cause it to expand, either directly or via controlled hydraulic pressure to the valve body (or needle in the case of a normal fuel injection valve).
The valve is opened by lifting the valve in the valve opening direction. On the other hand, at the end of fuel injection, the electric charge of the piezoelectric element is removed to eliminate the biasing of the valve body in the valve opening direction, and the valve body is driven in the valve closing direction by the fuel pressure or the biasing force of the spring to close the valve. ing.

[Problems to be Solved by the Invention] However, these fuel injection devices have the following problems, and further improvements have been desired.

(1) Normally, the valve is opened by a piezoelectric element, so it takes only several tens of microseconds, but the valve is closed by the fuel pressure or the biasing force of a spring. Therefore, there is a problem in that when the fuel pressure becomes low, the valve closing time becomes longer and the responsiveness may deteriorate.

(2) Since the piezoelectric element electrically has a predetermined capacity, it is charged by the voltage applied when the valve is opened and stores a certain amount of charge. Therefore, when the valve is closed, the electric charge stored in the piezoelectric element must be discharged, and charging and discharging are repeated each time the piezoelectric element is operated, so that it is difficult to avoid wasteful power consumption. This was thought to become a particular problem as the fuel injection cycle became shorter.

SUMMARY OF THE INVENTION The present invention has been made to solve these problems, and to provide a fuel injection device having high response characteristics in an on-off valve and low power consumption.

Structure of the Invention [Means for Solving the Problems] In order to achieve the above object, the present invention has the following structure as a means for solving the problems. That is, a fuel injection valve incorporating a first piezoelectric element that drives the valve body in the valve opening direction and a second piezoelectric element that drives the valve body in the valve closing direction, and a fuel injection valve that drives the piezoelectric element. In a fuel injection tJJ device equipped with a drive circuit, the drive circuit must have a predetermined inductance and be connected in series between the first piezoelectric element and the second piezoelectric element. Part 1. an element which forms a series circuit with the second piezoelectric element; and the series resonant circuit with the first piezoelectric element. a switching means that opens and closes between a second piezoelectric element, and an initial power for driving the piezoelectric element is supplied to the series resonant circuit, and when the switching means opens and closes, the fuel injection valve The first step is to open and close the valve. This is the configuration of the fuel injection device including a replenishment circuit that replenishes the electric power lost due to the operation of the second piezoelectric element.

Here, the first. The second piezoelectric element drives the valve body in the valve opening direction and the valve closing direction, and may directly drive the valve body against fuel pressure by its expansion action, The valve body, which is balanced to some extent by the fuel pressure, may be configured to be driven via one control oil pressure. In the latter case, it is easy to downsize the fuel injection valve.

The valve body is usually a needle in fuel injection valves, but
There is no problem even if the fuel injection valve has a configuration other than a needle valve.

The drive circuit is the first one. The device includes an element having an inductance that forms a closed circuit with the second piezoelectric element, switching means, and a supplementary circuit. The element having inductance is, for example, a coil, and together with the capacitive component of the piezoelectric element, forms a series resonant circuit having a predetermined frequency (localized wave number). There is no problem if the voltage is sufficiently high. Also, when the switching means is closed,
Since the electric charge of one piezoelectric element is instantly transferred to the other, semiconductor switching elements such as FETs, thyristors, and triacs can be used as long as the switching means has the same level of response as the resonance frequency and has a small on-resistance. It can be used regardless of.

The replenishment circuit is a circuit that supplies the above-mentioned series resonant circuit with initial power to drive the piezoelectric element, and also replenishes the power lost each time the piezoelectric element is activated. 1. The configuration may be such that a voltage is applied to one of the second piezoelectric elements, or the voltage may be applied to the piezoelectric element on the operating side at the time of replenishment.

[Operation] The fuel injection device of the present invention having the above configuration has a first and a second
The piezoelectric element drives the valve body to open and close the valve, and by opening and closing this series resonant circuit using the switching means of the series resonant circuit, the energy stored in one piezoelectric element is opened and closed. By transferring the electric charge from one side to the other, opening and closing the valve with less power loss is achieved. This is the first
The second piezoelectric element drives the valve body in the valve opening direction.
When a piezoelectric element is used to drive the valve body in the valve closing direction, power (energy) is consumed while switching between the valve open state and the valve closed state, but when the valve body is in one of the states. At times, the piezoelectric element consumes almost no power and functions simply as a charge storage element, in other words, as a capacitor. Therefore, when a series resonant circuit is formed with an element having inductance, most of the electric charge that was once stored in one piezoelectric element can be transferred to the other. At this time, the piezoelectric element on the side that has lost electric charge loses its biasing force, and the piezoelectric element on the side that has stored electric charge expands to open or close the valve body.

Naturally, energy is lost each time the valve is opened or closed, and this energy is replenished by the replenishment circuit.

[Examples] In order to further clarify the configuration of the present invention described above, preferred embodiments of the present invention will be described next.

Fig. 1 is a configuration diagram showing a circuit of a fuel injection device as an embodiment of the present invention together with a block diagram of an electronic control device, and Fig. 2 is a schematic configuration of a 4-cylinder diesel engine configured using the fuel injection device of the embodiment. 3 and 3 are sectional views showing the structure of the fuel injection valve, and the following description will be made with reference to these drawings as appropriate.

As shown in FIG. 2, a four-cylinder diesel engine 1 constructed using the fuel injection device of the embodiment is provided with a fuel injection valve 8 for direct injection into a combustion chamber for each diesel cylinder. The intake air to this diesel engine 1 is supercharged I
This is done from T through the intake manifold 9.

The fuel injection valve 8 is connected via a fuel supply pipe 10 to a fuel pressure accumulation pipe 11 common to each cylinder. The fuel accumulator pipe 11 has a pressure accumulator chamber 12 with a constant volume inside thereof, and the fuel in this pressure accumulator chamber 12 is supplied to the fuel injection valve 8 via the fuel supply pipe 10. On the other hand, the pressure accumulation chamber 12 is connected via a fuel supply pipe 13 to a discharge port of a fuel supply pump 14 whose discharge pressure can be controlled.

A suction port of the fuel supply pump 14 is connected to a discharge port of a fuel pump 15, and a suction port of the fuel pump 15 is connected to a fuel reservoir tank 16. Each fuel injection valve 8 is also connected to a fuel reservoir tank 16 via a fuel return conduit 17 . The fuel pump 15 is provided to feed the fuel in the fuel reservoir tank 16 into the fuel supply pump 14, and the fuel supply pump 14 can be used even without the fuel pump 15.
If it is possible to suck fuel into the fuel pump 15
There is no need to specifically provide this. On the other hand, the fuel supply pump 14 is provided to discharge high-pressure fuel, and the high-pressure fuel discharged from the fuel supply pump 14 is delivered to the pressure accumulation chamber 1.
It is accumulated within 2. This pressure is also called rail pressure.

The diesel engine 1 also includes two crank angle sensors 21.2 to detect the operating state of the engine 1.
2, a cooling water temperature sensor 24, a boost pressure sensor 26, a fuel pressure sensor 28, etc. are provided. The electronic control device 30 is
The output of each of the above sensors and the amount of depression of the accelerator pedal 32,
That is, based on the output of the accelerator sensor 34 that detects the load, the fuel injection amount and fuel injection timing of the diesel engine 1 are controlled via the fuel injection valve drive device 40 and the pump drive device 45, and the output of the diesel engine 1 is controlled. The configuration of the electronic control device 30 and the processing it performs will be described later.

Next, the structure of the fuel injection valve 8 will be explained. As shown in FIG. 3, the fuel injection valve 8 includes a fuel injection valve main body 50 to which a fuel inlet port '48'' is assembled, and a fuel injection valve main body 50.
The nozzle 53 is fixed by a nozzle holder 51 via a spacer 52, and 2g actuators 54, 55 using piezoelectric elements are provided. Inside the fuel injection valve body 50, spacer 52, and nozzle 53, there are a control rod 56, a pressure pin 57, and a needle 5 arranged in series with each other.
8 is slidably inserted. Upper end 6 of control rod 56
0 is machined to have a small diameter, and is fitted into the cylinder sleeve 62 of the actuator 55 to form a first control rod pressurizing chamber 63. This upper end portion 60 and the fuel injection valve main body 50 form a fuel chamber 65, and this fuel chamber 65 is connected to the fuel inlet 4.
8 and a pressure accumulation chamber 12 via a fuel supply pipe 10 (Fig. 2).
connected to. Therefore, the fuel pressure in the pressure accumulation chamber 65 is applied to the fuel chamber 65, and the fuel pressure (rail pressure) in the fuel chamber 65 is increased by the stepped portion upper surface 56a of the upper end portion 60 of the control rod 56.
act to press the control rod 56 downward (in the direction of the arrow in FIG. 3).

On the other hand, the needle 58 has a conical pressure receiving surface, and a needle pressurizing chamber 71 is formed around this pressure receiving surface 70.

The needle pressurizing chamber 71 is connected to the fuel chamber 65 via a fuel passage 72 on the one hand, and to the nozzle formed at the tip of the nozzle 53 via an annular fuel passage 73 formed around the needle 58 on the other hand. It is connected to the hole 53a. A biasing spring 74 that biases the pressure pin 57 downward is inserted into the fuel injection valve body 50, and the needle 58 is also pressed downward by the biasing spring 74. This biasing spring 74
is for keeping the fuel injection valve 8 closed when both actuators 54 and 55 are not operating. Further, the control rod 56 has a conical pressure receiving surface 75 at its intermediate portion, and a second control rod pressurizing chamber 76 is formed around this pressure receiving surface 75.

Next, the first control rod halo pressure chamber 63. The structure of the actuator 54,55 that drives the control rod 56 via the second control rod pressurizing chamber 76 will be described. Since both actuators have the same configuration using a piezoelectric element as a driving source, the actuator 54 will be explained below.
The numbers of the components of the actuator 55 are shown in parentheses.

The actuator 54 (55) is fixed to the fuel injection valve main body 50, and its hydraulic piston 80 (81) is
It is slidably mounted in the cylinder 82 (83) via an O-ring 84 (85) while maintaining good sealing performance. The actuator 54 (55) is the fuel injection valve 50
It consists of a casing 86 (87) fixed to the hydraulic piston 80 (81) and a piezoelectric element 90 (91) inserted between the casing 86 (87). This piezoelectric element 90 (91) has a laminated structure in which a large number of thin plate-shaped piezoelectric elements are laminated.
When voltage is applied to 0 (91), piezoelectric element 90 (9
1) causes longitudinal strain due to electrostrictive effects, ie, extends in the longitudinal direction. Although the amount of elongation is a small amount, for example, about 50μ, the response is extremely good, and the response time from application of voltage to elongation is about 80tiSeC.

When the piezoelectric element 90 (91) extends, the hydraulic piston 80 (81) moves in a direction that reduces the volume of the fuel-filled chamber in the cylinder 8.2 (83). As a result, the fuel in the cylinder 82 (83) is
) flows into the control rod pressurizing chamber 76 (63) and moves the control rod 56. At this time, cylinder 82 (8
3) Cross-sectional area and second (first) control rod pressurizing chamber 76'
(63) according to the ratio with the cross-sectional area of the hydraulic piston 80 (8
The amount of operation in 1) is amplified, and the piezoelectric element 90 (91)
The control rod 56 has an elongation m of approximately 400 μm.
is moved to μm.

Note that when a voltage is applied to the piezoelectric element 90 (91), the piezoelectric element 90 (91) accumulates electric charge by its own capacity.
Even if the application of voltage is stopped, it will remain in an extended state unless it does any particular work.

If the fuel in the first or second control rod pressurizing chambers 63, 76, that is, the control oil, is not pressurized, the needle 5
A downward force acting on the stepped portion upper surface 56a of the control rod 56, a downward force due to the biasing spring 74, and an upward force acting on the pressure receiving surface 70 of the needle 58 are applied to 8. At this time, the diameter of the control rod 56, the spring force of the biasing spring 74, and the area of the pressure receiving surface 70 of the needle 58 are set so that the sum of the downward forces is slightly larger than the upward forces. Therefore, a downward force is acting on the normal needle 58, and as a result, the normal needle 58 is moved toward the nozzle hole 53a.
is closed.

In this state, the piezoelectric element 90 of the actuator 54
When a voltage is applied to the piezoelectric element 90, the hydraulic piston 80 moves to the left (in the direction of the arrow in FIG. 3), and as a result, the control hydraulic pressure in the control rod halo pressure chamber 76 of the cylinder 2 increases. . At this time, an upward force (in the direction of arrow U) acts on the receiving surface pressure 75 of the control rod 56, so the control rod 56 rises, and as a result, the needle 58 rises and fuel enters the combustion chamber from the nozzle hole 53a. Injected. As mentioned above, the response at this time is about 80 μSEC, which is extremely fast. Further, when the control rod 56 moves in the direction of the arrow U, the piezoelectric element 91 of the actuator 55 is not extended, and the hydraulic piston 83 is also in a state of being pulled up in the direction of the arrow U.

Next, when the charge stored in the piezoelectric element 9O of the actuator 54 is released and a voltage is applied to the piezoelectric element 91 of the other actuator 55, the piezoelectric element 90 contracts and the second control rod pressurizing chamber 76 As the control hydraulic pressure within the first control rod pressurizing chamber 63 decreases, the piezoelectric cord 91 extends, and the control hydraulic pressure within the first control rod pressurizing chamber 63 increases. As a result, the control rod 56 and needle 5B are lowered and fuel injection is stopped. Since this operation is also performed by a piezoelectric element, the response time is approximately 80 μsec, which is extremely fast.

Next, the configuration and function of the electronic control device 30 and fuel injection valve drive device 40 included in this embodiment will be explained. As shown in FIG. 1, an electronic control device 30 that operates by receiving power from a battery 102 via an ignition switch 100 includes a well-known CPU 1'IO, ROM 11,
1. The timer 115 . Input port 117. It is configured as a logic operation circuit in which output ports 118 and the like are interconnected by a bus 119. The input port 117 has the crank angle sensors 21, 22,
Cooling water temperature sensor 24. A boost pressure sensor 26°, a fuel pressure sensor 28 and an accelerator sensor 34 are connected, and the CPU
110 inputs the crank angle (
Therefore, the operating state of the diesel engine 1 such as the engine speed N) of the diesel engine, the cylinder discrimination signal, the cooling water temperature hw, the boost pressure B, the fuel pressure P, and the load can be read. On the other hand, the output port 118 is connected to the four fuel injection valves 8.
The fuel injection valve drive device 40 and the fuel supply pump 1 that drive the
It is connected to a pump drive device 45 that drives 4,
The CPU 110 controls opening and closing of the fuel injection valve 8 and fuel supply through the output port 118. Note that since the control of the fuel supply pump 14 is not directly related to the gist of the present invention, the explanation will be omitted here, assuming that the fuel pressure P is controlled in proportion to the rotation speed N of the diesel engine 1. Further, in FIG. 1, the circuit for driving one of the fuel injection valves 8 of the fuel injection valve driving device 40 is omitted. The three-cylinder fuel injection valve 8 is also controlled by the same circuit configuration via the output capo-1-118.

The fuel injection valve drive device 40 receives a voltage of about 250V that is output by boosting the battery voltage from the drive voltage generation circuit 120, and operates the thyristors 5CR1, 5CR2, and S.
It is configured to exclusively drive the piezoelectric elements 90 and 91 by switching CR3. The positive output of the drive voltage generation circuit 120 is connected to the anode of the thyristor 5CR1, and
The cathode side of CRI is connected to one end of resistor R1. The other end of the resistor R1 is connected to the cathode of another thyristor 5CR2, the anode of the thyristor 5CR3, and the piezoelectric element 91 of the actuator 55. The anode of the thyristor 5CR2 is connected to the piezoelectric element 90 of the other actuator 54 via the coil L2, while the cathode of the thyristor 5CR3 is connected via the coil L3. In addition, each thyristor 5CRI, 5
The gates of CR2 and 5CR3 are directly connected to and driven by the output port 118.

Therefore, the processing performed by the electronic control unit 30 will be explained next using the flowcharts shown in FIGS. , 5CR2, 5CR3 and the corresponding opening/closing of the fuel injection valve will be explained.

The electronic control device 30 starts operating when the ignition switch 100 is turned on, and first performs a so-called initialization process in step 200. Here, in addition to initializing the clear flag and the like of the internal register of the CPU 110, a process of outputting a pulse signal to the gate of the thyristor 5CR1 via the output port 118 is performed. As a result, the thyristor 5CR1 becomes conductive, and the high voltage output from the drive voltage generation circuit 120 is applied to the piezoelectric element 91 of the actuator 55 of the fuel injection valve 8, and the voltage across the piezoelectric element 91 is It is determined according to the output of 120. In this state, the piezoelectric element 91 expands,
The needle 58 of the fuel injection valve 8 is pressed in the arrow direction (downward) in FIG. 3, and the fuel injection valve 8 is brought into a closed state.

After electric charge is stored in the piezoelectric element 91, no current flows through the thyristor 5CRI, so the thyristor 5CR1 is turned off.

In step 210 following step 200, a process is performed to read operating conditions such as the rotation speed N, negative load, cooling water temperature ThW, boost pressure P, and fuel pressure P of the Devil engine 1 from each sensor via the input port 117. It is done. In the following step 220, the process of calculating the fuel injection amount τ based on the load and taking into account other operating conditions is further performed in step 2.
At 30, processing for calculating the start and end times of fuel injection is performed.

In response to these results, CPUll0 performs step 24
0, a process is performed to set the fuel injection start timing and end timing in the timer 115. As a result, the timer 115 starts self-running and outputs an interrupt signal to the CPU 110 when the fuel injection start timing comes.

In the following step 250, the fuel supply pump 14 is controlled via the output port 118 and the pump drive device 45,
The fuel pressure P is controlled, but since it is not directly related to the present invention, a description of this control will be omitted. The following step 260 is a power replenishment control routine in which the operating power of the piezoelectric elements 90 and 91 is replenished via the fuel injection valve drive device 40. This routine will be described later with reference to FIG. 4(C). After completing the process in step 260, the process returns to step 210 and repeats the process for fuel injection described above.

When the fuel injection start timing set in the process of step 240 described above is reached, an interrupt is generated by the timer 115, and the CPU 110 executes the fuel injection control interrupt routine shown in FIG. 4(B). In this interrupt routine, first, in step 300, the thyristor 5CR3
A process is performed in which a control signal is output to the gates of the output capos 1 to 118 to turn them on. At this time,
The piezoelectric element 91 of the actuator 55 is expanded and stores electric charge, while the piezoelectric element 91 of the actuator 54 is in an initial state (retracted/v). Therefore, when the thyristor 5CR3 becomes conductive, this circuit becomes
Since it is a series resonant circuit having a predetermined resonant frequency determined by the inductance of the coil 3 and the capacitance of the piezoelectric element 90, almost all the electric charge stored in the piezoelectric element 91 within several tens of μSeC is transferred to the other piezoelectric element. Move to piezoelectric element 90. As a result, the piezoelectric element 91
As the piezoelectric element 90 contracts, the piezoelectric element 90 expands, and the control rod 56 is pushed upward to open the fuel injection valve 8, and fuel is injected through the nozzle hole 53aJ of the nozzle 53. Electric charge is transferred from the piezoelectric element 91 to the piezoelectric element 90
When the piezoelectric element 90 moves to , the thyristor 5CR3 loses its holding current and turns off, and the charges accumulated in the piezoelectric element 90 are not released anywhere. Of course, some of the electric power is used to drive the control rod 56 upward, but since the energy (charge) stored in the piezoelectric element is several times larger than the electric power consumed, the control rod 56 is driven upward. Even after driving the piezoelectric element 90
is still in a state where electric charge is stored. It should be noted that once the piezoelectric element 90 has expanded and entered the valve open state, the piezoelectric element 90 does almost no work, so that almost no electric charge is lost.

In the following step 310, it is determined whether the valve closing timing has come. That is, it is checked whether the fuel injection end timing set in the timer 115 has been reached. When the fuel injection end timing comes, the process moves to step 320, where a control signal is output to the gate of the thyristor 5CR2 via the output boat 118 to turn on the thyristor 5CR2.

At this time, the piezoelectric element 91 of the actuator 54
stores an electric charge, and the electric charge moves in the opposite direction to the operation in step 300 described above, the piezoelectric element 90 contracts and the piezoelectric element 91 expands, and the salt 11 injection valve 8 is closed. Ru. After the above processing is completed, the process returns to rRTNJ and the interrupt control routine ends.

In this way, even after the fuel injection valve 8 performs one fuel injection operation (opening/closing valve operation), an electric charge remains in the piezoelectric element 91, so the above-mentioned operation can be repeated several times without particularly replenishing the electric power. Can be repeated. However, as the valve is repeatedly opened and closed, the stored charge naturally decreases, and it becomes necessary to replenish the energy.

The process of step 260 of the main control routine shown in the flowchart of FIG. 4(A), ie, the electric horn replenishment control routine corresponds to this, and replenishes the lost energy. In the power replenishment control routine, as shown in FIG. 4(C),
First, in step 400, it is determined whether or not one fuel injection valve 8 has been injected twice. Since replenishment is performed once every two fuel injections, if the replenishment is not performed twice, no processing is performed and the replenishment is carried out to rNEXTJ. On the other hand, after two fuel injections,
Proceeding to step 410, a control signal is output to the gate of thyristor 5CR1 to turn it on. Since this process is performed at the timing when the fuel injection valve 8 is closed, the piezoelectric actuator of the actuator 55 is In the piezoelectric element 91,
Electric power is supplied from the drive voltage generation circuit 120, and the charge lost due to the opening of the fuel injection valve 8 is replenished. After the processing in step 410, the process exits to rNEXTJ and this control routine ends. The timing chart in FIG. 5 shows how the fuel injection valve is opened and closed by the operation of the thyristors 5CR2 and 5CR, and the above-mentioned replenishment operation by the operation of the thyristor 5CRI.

In the present embodiment configured as described above, conventionally, when closing the fuel injection valve 8, the piezoelectric element used in the actuator is ignited the electric charge accumulated during the valve opening operation. By using the second piezoelectric element 90,91 to transfer the charge from one to the other, it is possible to avoid wasting power and to make the efficiency extremely high. actual,
Since the energy conversion efficiency of the piezoelectric element is approximately 75%, the overall operating efficiency was improved by at least 1.5 times in this example. Furthermore, in the fuel injection valve 8 of this embodiment, the control rod 56. Since needle 58 is balanced by fuel pressure, piezoelectric element 90.91
opens against fuel pressure.

Rather than closing the valve, the first and second valves, which are independent of fuel pressure,
The control rod only controls the hydraulic pressure of the pressurizing chambers 63' and 76, and the electric power applied to the piezoelectric elements 90 and 91 is also much smaller.

Further, in this embodiment, since the expansion action of the piezoelectric element 90 is also used when closing the fuel injection valve, its response is extremely fast, about 80 μsec. As a result, it is possible to accurately control the fuel injection amount and fuel injection timing, and it is also possible to improve fuel efficiency and exhaust gas purification.

Although one embodiment of the present invention has been described above, the present invention is not limited to this embodiment. For example, one triac may be used in place of the thyristors 5CR2 and 5CR3 to allow current to flow in both directions. It goes without saying that the present invention can be implemented in various ways without departing from the gist of the present invention, such as a switching configuration or a configuration in which the control rod is driven against fuel pressure.

Effects of the Invention As detailed above, according to the fuel injection device of the present invention,
The energy consumed to drive the fuel injection valve can be kept extremely low, and the valves can both be opened and closed at high speed (responsiveness), which is an extremely excellent effect.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a circuit of a fuel injection device according to an embodiment of the present invention together with a block diagram of an electronic control device, and FIG. 2 is a 4-cylinder D-U constructed using the fuel injection device of the embodiment.
Figure 3 is a cross-sectional view showing the structure of the fuel injection valve, Figure 4 (A>, (B), (C))
are flowcharts showing each part of control in each embodiment, and FIG. 5 is a time chart showing an example of control in the embodiment. 1...Devil engine 8...Fuel injection valve 12...Accumulation chamber 14...Fuel supply pump 21.22...Crank angle sensor 28...Fuel pressure sensor 34...Accelerator sensor 50 ... Fuel injection valve body 53 ... Nozzle 54, 55 ... Actuator 56 ... Control rod 58 ... Needle

Claims (1)

[Scope of Claims] A fuel injection valve incorporating a first piezoelectric element that drives the valve body in the valve opening direction and a second piezoelectric element that drives the valve body in the valve closing direction; and a drive circuit for driving an element, the drive circuit having a predetermined inductance and connected in series between the first piezoelectric element and the second piezoelectric element. an element configured to form a series resonant circuit together with the first and second piezoelectric elements; a switching means for opening and closing the series resonant circuit between the first and second piezoelectric elements; Initial power is supplied to the series resonant circuit to drive the piezoelectric element, and when the switching means is opened or closed, power is lost due to the operation of the first and second piezoelectric elements that open and close the fuel injection valve. A fuel injection device comprising a replenishment circuit for replenishing the electric power generated.