JPH11303706A - Fuel injection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To display a sufficient engine output over from a low speed to a high speed or from a light load to a heavy load, by preventing generation of output insufficiency at a high speed by a cause of a bubble generated by extending or contracting an impulsive extension element in a short time. SOLUTION: In a fuel injection device having a pressurizing chamber 32 pressurizing fuel, injection port 41 for injecting fuel, injection passage 15a guiding fuel to this injection port 41 from the pressurizing chamber 32, high pressure pump impulsively generating a high pressure in fuel being in contact with one end part in the pressurizing chamber 32 by extending and/or contracting the impulsive extension element 17 whose one end part is facing with the fuel, and a valve means provided in the vicinity of the injection port to be opened corresponding to action of the high pressure pump, a sectional area of the injection passage 15a is formed smaller than a sectional area of the pressure chamber 32, a fuel supply passage 600 communicates with this injection passage 15a, and fuel therefrom can be supplied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection device for injecting fuel by an impulsively high pressure.

[0002]

2. Description of the Related Art The applicant attaches an injector to a combustion chamber or a supply path of fresh air to the combustion chamber, and installs an impact expansion element made of an electrostrictive element or a magnetostrictive element in a pressurized chamber communicating with the injector. By facing the inside and extending the shock-extending element at a predetermined timing, a shock high pressure is generated in the fuel in contact with the end of the shock-expanding element,
This shocking high pressure is transmitted to the injector of the injector so that the fuel is injected from the injector to the combustion chamber or the outside of the supply passage, and then the fuel that contracts the shock-elongating element in preparation for the next injection. An injection device was proposed.

[0003]

When the shock-elongating element is extended or contracted in a short time, the fuel in contact with the end of the shock-elongating element is subject to pressure fluctuation with time due to the expansion or contraction. This pressure fluctuation propagates with time from the end of the shock-extending element in contact with the fuel to the injection valve that opens and closes the injection port.

FIG. 10 and FIG. 11 are diagrams showing the progress of pressure fluctuation when the impact extension element is extended in a short time. 10 and 11, p0 indicates an absolute pressure of 0 atm, and p0
Reference numeral 1 indicates a state immediately before the elongation operation, that is, a pre-compression state at each part pressure, p2 indicates an injector valve opening pressure, and p3 indicates a fuel vapor pressure.

[0005] The pressure waveform shown to the left indicates how the pressure of the fuel in contact with the end changes due to the elongation of the impact expansion element over time.

[0006] The liquid fuel particles in contact with the end portions are pushed by the end portions, move, increase in density, and increase in pressure. At the moment when the end portion comes to rest, the pressure becomes the highest and this is the first impact pressure (pw1). The first impact pressure pw1 increases as the extension speed (the extension distance L divided by the extension time t) of the impact extension element increases. That is, the shorter the extension time t and the longer the extension distance L, the greater the first impact pressure pw1. After the end comes to rest, no forcing is applied to the fuel particles, and the fuel particles at a higher density position move to a lower density portion in front. Since this movement is accompanied by inertia, the density of the fuel particles in the portion in contact with the end becomes low. The degree of the sparseness is the moving speed (the larger the first first impact pressure pw1 is, the larger the moving speed is).
The greater the value, the lower the density of the fuel particles. The pressure due to this sparse state is the first sparse pressure (nwl = less than preload p1)
It is. After this, the fuel particles move from the front to the part where the density of the fuel particles in contact with the end is low, and this movement involves inertia. Become. The pressure due to this dense state is the second impact pressure p
w2. Thereafter, at the portion in contact with the end, the pressure fluctuates in the order of the second sparse pressure nw2 and the third impact pressure pw3. This pressure fluctuation is a natural vibration after the end portion has stopped,
The period T of the vibration is shorter as the preload p1 (correlated with the density of the fuel particles before the vibration) is larger, irrespective of the moving speed and the moving time t of the end portion causing the natural vibration. As the time elapses, if the pressure waveform is moved rightward, the pressure state of each part is known, and the moving speed becomes the sound speed.

As shown in FIG. 10, when the elongation speed is particularly fast and the elongation time t1 is short, the first impact pressure (pwl) becomes extremely large, so that the amplitude of the subsequent natural vibration becomes large and the first sparseness is increased. The pressure (nw1) is much lower than the preload p1 and lower than the fuel vapor pressure p3. That is, bubbles are generated.

On the other hand, when the extension speed is slow and the extension time t2 is long (t2> t1) as shown in FIG. 11, the first impact pressure (pw1) does not become sufficiently large, and the amplitude of the subsequent natural vibration becomes small. The first sparse pressure (nw1) does not fall below the preload p1 but does not fall below the fuel vapor pressure p3, and no bubbles are generated. It is important for the injection that no air bubbles are generated, but if the elongation speed is low, the first impact pressure (pw1) reaching the valve of the injection port is small, and if it is larger than the valve opening pressure p2 of the injector, the fuel However, the injection speed cannot be increased and the injection amount decreases.

FIG. 12 is a diagram showing the course of pressure fluctuation when the impact extension element is contracted in a short time. In FIG. 12, p0 indicates an absolute pressure of 0 atm, p1 indicates a pressure immediately before the elongation operation is started, that is, indicates a precompression state with the pressure of each part, p2 indicates a valve opening pressure of the injector, and p3 indicates a fuel vapor pressure. .

[0010] The pressure waveform shown to the left shows how the fuel in contact with the end due to the contraction of the shock-stretching element exhibits pressure fluctuations over time. The liquid fuel particles in contact with the ends decrease in density and pressure as the impact extension element contracts and the ends move. At the moment when the end comes to rest, the pressure becomes the lowest and this is the first pressure drop (nwl). The first pressure isostatic pressure nwl decreases as the contraction speed (shrinkage distance L divided by contraction time t3, which is equal to the moving speed of the end portion) of the shock-elongating element increases. That is, the shorter the contraction time t3 (= movement time of the end), the shorter the contraction distance L
The longer the (= movement distance of the end), the smaller the first pressure-releasing pressure nWl. After the end portion stops, no forcing force acts on the fuel particles, and the high-density fuel particles move forward to the position with low density. Due to the inertial movement, the density of the fuel particles in the portion in contact with the end increases. The pressure due to this dense state becomes the first impact pressure pw1. The density of the fuel particles (the height of the pressure) increases as the moving speed (the lower the first first sparse pressure nw1), the higher the density of the fuel particles.

After this dense state, the fuel particles move to the lower density portion in front. Since this movement is accompanied by inertia, the density of the regenerated fuel particles is low at the portion in contact with the end. The pressure due to this sparse state becomes the second sparse pressure nw2. Thereafter, at the portion in contact with the end, the pressure fluctuates in the order of the second impact pressure pw3 and the third sparse pressure nW3. This pressure fluctuation is a natural vibration after the end moves and stops as the shocking extension element stops after the contraction, and the period of the vibration T
Is the moving speed and the moving time t of the end portion causing the natural vibration.
Regardless of 3, the larger the preload p1 (correlated with the density of the fuel particles before vibration), the shorter the preload.

If this pressure waveform is moved rightward with the passage of time, the pressure state of each part can be known, and the moving speed is the speed of sound.

As shown in FIGS. 10 and 11, when the pressure wave propagates from the end to the pressure chamber outlet, the injector and the like, the first impact pressure pw1 and the first sparse pressure nw
1, the second impact pressure pw2, and the second sparse pressure nw2 sequentially propagate.

When the first impact pressure pw1 reaches the injector, the injection is started, and the injection ends when the fuel pressure falls below the valve opening pressure of the injector. Shortly after
The first low pressure nwl is reflected by the closed injector and propagates in the opposite direction. Along with this propagation, the fuel in each portion evaporates sequentially to form bubbles, and liquefaction occurs in which the bubbles are crushed. That is, it is as if the air bubbles move in the opposite direction. Due to the attenuation during the propagation, the absolute pressure of the first sparse pressure nw1 increases, and the bubbles disappear when the pressure becomes equal to or higher than the vapor pressure of the fuel.

As described above, when the bubble does not disappear between the pressurizing chamber and the injector and exists, the first impact pressure pw1 generated by the next elongation propagates, and when it collides with the bubble, it causes interference and attenuates. Then, the first impact pressure pw1 after passing through the air bubbles becomes small. If the value of the first impact pressure pw1 is smaller than the valve opening pressure p2 of the injector, injection becomes impossible.

Similarly, the pressure propagation to each part at the time of contraction shown in FIG. 12 is performed in the order of a first low pressure nw1, a first impact pressure pw1, a second low pressure nw2, and a second impact pressure pw2. Propagate separately. The first low pressure nw1 reaches the injector, and the first low pressure nw1 is reflected by the closed injector,
Propagating in the opposite direction. Along with this, the bubbles move in the opposite direction. The first impact pressure pw1, which propagates in the valve direction of the injector, interferes with the backflowing bubbles and attenuates, decreases before reaching the valve of the injector, and becomes incapable of injection if smaller than the valve opening pressure p2 of the injector. Would.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and is intended to prevent shortage of output at high speed due to bubbles generated by extending or contracting an impact extension element in a short time, It is an object of the present invention to provide a fuel injection device capable of exhibiting a sufficient engine output from low speed to high speed or from low load to high load.

[0018]

Means for Solving the Problems In order to solve the above problems and achieve the object, the present invention has the following constitution.

According to the first aspect of the present invention, there are provided a pressurizing chamber for pressurizing the fuel, an injection port for injecting the fuel, an injection passage for guiding the fuel from the pressurizing chamber to the injection port, and an end portion. A high-pressure pump provided in the vicinity of the injection port, wherein the high-pressure pump is provided near the injection port by expanding or contracting the shock-extending element facing the fuel to thereby shock-pressurize the fuel in contact with the end in the pressurizing chamber. A valve means that opens corresponding to the operation of the fuel injection device, wherein a cross-sectional area of the injection passage is smaller than a cross-sectional area of the pressurized chamber, and the fuel supply passage is communicated with the injection passage. A fuel injection device wherein fuel can be supplied from an injection passage. ].

According to the first aspect of the present invention, the fuel in contact with the end of the pressurizing chamber is made to have a high pressure by expanding or contracting the shock-extending element, so that the fuel is discharged from the pressurizing chamber. The valve is opened by the fuel pressure through the injection passage to the injection port to open the valve means to inject fuel, but a large first impact pressure is generated by the extension of the impact extension element in a short time,
Subsequently, an extremely large first pressure-elasticity is generated, or an extremely large first pressure-elasticity is generated by contraction of the shock-elongating element in a short period of time, and even when bubbles may be generated, the bubbles may be generated. While entering the injection passage from the pressurizing chamber and moving in the direction of the injection valve, the bubbles are crushed and disappeared by the fuel pressure supplied from the fuel supply passage to the injection passage, so that the bubbles generated in the fuel can be reduced, As a result, shortage of output at high speed can be prevented from occurring, so that sufficient engine output can be exhibited from low speed to high speed or from low load to high load.

According to a second aspect of the present invention, there is provided a fuel injection device according to the first aspect, wherein a wall of the pressurizing chamber connected to a fuel discharge port to the injection passage of the pressurizing chamber is formed in a funnel shape. . ].

According to the second aspect of the present invention, even if bubbles are generated in the pressurized chamber due to the expansion of the shock-elongating element in a short time, the bubbles are smoothly discharged from the pressurized chamber to the injection passage. The bubbles can be more reliably crushed and eliminated by the fuel pressure supplied from the fuel supply passage to the injection passage.

According to a third aspect of the present invention, there is provided the fuel injection device according to the first or second aspect, wherein a check valve is provided in the fuel supply passage. ].

According to the third aspect of the present invention, the check valve provided in the fuel supply passage prevents the impact pressure propagating in the injection passage toward the injection valve from dissipating in the fuel supply passage more reliably. it can.

According to a fourth aspect of the present invention, "the pressurizing chamber includes:
4. The fuel injection device according to claim 1, wherein a return fuel pipe for returning fuel to a fuel supply source side is connected, and the return fuel pipe is provided with a pressure regulating valve. ].

According to the fourth aspect of the present invention, the return fuel pipe connected to the pressurizing chamber is provided with a pressure regulating valve, and by setting the fuel in the pressurizing chamber to a predetermined pressure, the impact pressure is further increased, and the pressure of the bubbles is reduced. Generation can be made difficult.

According to a fifth aspect of the present invention, there is provided a method as described above, wherein the end of the shock-stretching element is constituted by a plunger which can be released from the main body of the shock-stretching element, and the plunger is always moved toward the main body of the shock-stretching element. The fuel injection device according to any one of claims 1 to 4, further comprising an urging means for urging. ].

According to the fifth aspect of the present invention, when the expanded impact extension element contracts, the main body of the impact extension element is released from the plunger and contracts, and the plunger is slower than the contraction of the impact extension element. The plunger is moved by the urging means. At this time, the moving speed of the plunger is reduced, so that bubbles generated in the fuel can be reduced. Sufficient engine output can be exhibited from load to high load.

The invention according to claim 6 is characterized in that the shock-extending element is expanded by charging the high-voltage shock source and contracted by discharging, and the discharging time is made longer than the charging time. The fuel injection device according to any one of claims 1 to 4. ].

According to the sixth aspect of the present invention, when the shock-elongating element expanded by the discharge of the shock high-voltage generating source contracts, the discharge time is set longer than the charging time, and the fuel during contraction is set to be longer. The moving speed of the end in contact with the air becomes slower and the bubbles generated in the fuel can be reduced, so that the bubbles do not cause a shortage of output at high speed, and sufficient from low speed to high speed or from low load to high load. High engine output.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a fuel injection device according to the present invention will be described. FIG. 1 is a configuration diagram of a four-cycle internal combustion engine to which the fuel injection device according to the present invention is applied. The engine 1 includes a cylinder head 2 that forms an upper part of the combustion chamber 43.
And a cylinder block 3 constituting a cylinder of the combustion chamber 43
And a crankcase 4 forming a crankcase.

The crankshaft 5 in the crank chamber is connected to a connecting rod 10 connected to the crankpin 6 and the piston pin 7.
0 to the piston 8. Cylinder head 2
Is provided with an intake pipe 9, and an intake valve 10 is attached to an end of the intake pipe 9 so as to face the combustion chamber 43, and opens and closes an opening of the intake pipe 9. An exhaust pipe 11 is provided in the cylinder head 2, and an exhaust valve 12 is attached to an end of the cylinder head 2 so as to face the combustion chamber 43, and opens and closes an opening of the exhaust pipe 11. Cylinder head 2
A spark plug 13 is attached to the center of the.

In this embodiment, an injector 14 for directly injecting fuel into the combustion chamber 43 is provided facing the inside of the combustion chamber 43 from the upper surface of the cylinder head 2. The injector 14 is connected via a fuel pipe 15 to a high-pressure generator 16 serving as a high-pressure pump according to the present invention. Further, as shown in the figure, the position of the injector 14 is provided on the upper surface of the cylinder head 2 to form an in-cylinder injection structure. However, instead of this, the injector 14a shown by a chain line May be provided. Alternatively, direct injection in a cylinder may be performed by providing the injector on the side wall of the cylinder block 3 like an injector 14b indicated by a dashed line.

The high-pressure generating device 16 includes a high-impact high-voltage source composed of a piezoelectric element, a magnetostrictive element, and a piezoelectric element and a magnetostrictive element connected in series, which will be described later. This shock high voltage source is connected to the control circuit 18 and is driven and controlled at a predetermined timing.

The injector 14 has a fuel supply pipe 2
The fuel is introduced from the fuel tank 22 by the fuel pump 19 which is a low-pressure pump via 1. A filter 20 is provided at an inlet of the fuel supply pipe 21 in the fuel tank 22.

The high pressure generator 16 includes a return fuel pipe 2
The return fuel pipe 23 is provided with a pressure regulating valve 101 for adjusting the pressure. In order to apply a stable preload to the downstream portion including the high pressure generator 16, a pressure regulating valve 101 is provided to adjust the pressure and to perform accurate fuel injection.

The discharge pressure of the low-pressure pump is maintained at all times or when the injector 14 is shut off.
Is higher than the cutoff pressure, and the air such as air and vaporized fuel inside the fuel pipe 15 and the injector pass through the pressure regulating valve 101 together with the fuel and return to the upper portion on the fuel tank side having an air vent hole (not shown) at the upper portion. Bubbles are separated in the fuel tank 22 and do not flow to the fuel supply pipe 21 again. As a result, the fuel pipe 15 and the inside of the injector 14 are filled with the fuel, so that the shocking high-pressure wave reliably propagates, and the shocking high-pressure wave collides with the portion immediately before the injection port in the injector 14 to further increase the pressure. Make it possible.

FIG. 2 is a detailed configuration diagram of the high-pressure generator 16 and the injector 14 in the above embodiment. The injector 14 has a case body 2 having an injection port 41 at the tip.
The injection valve 41 is attached to the injection port 41. The injection valve 25 is always urged by the spring 26 in the closing direction. The fuel pipe 15 is connected to the injector 14 via a cap nut 27.

As will be described later, the injector 14
When the shocking high-pressure wave propagates, it collides with the inner surface of the injection valve 25 and further rises in pressure. By the energy, the injection valve 25 is pushed open against the spring 26, and fuel is injected. Further, the valve opening pressure of the injection valve 25 by the spring 26 is set higher than the pressure by the pressure regulating valve 101.

That is, when the pressure difference between the combustion chamber to be injected with fuel and the inside of the case body 24 is smaller than a predetermined value corresponding to the spring 26, the injection valve 25 is kept closed. On the other hand, when the shock high pressure wave arrives and the pressure difference between the inside and outside of the valve becomes larger than a predetermined value, the injection valve 25 is opened and fuel is injected.

The high-pressure generator 16 has, for example, a cylindrical case body 31 and a case 500, and a pressurizing chamber 32 is formed inside the case body 31. On one end side of the pressurizing chamber 32, the shock-elongating element main body 17a and the plunger 1
An impact elongating element 17 serving as an impulse high-voltage generating source constituted by a device including 7b or the like is mounted. The shock-extending element 17 generates a shocking high-pressure wave in the pressure chamber 32 to generate the pressure chamber 3.
2 to apply a shocking pressure to the fuel in 2.

The plunger 17b is detachable from the end of the impact extension element main body 17a and is arranged so as to face the fuel in the pressurizing chamber 32.

The main body 17a of the shock-elongating element is
0, rigidly fixed within the shock-extending element body 17a.
A predetermined gap 50 is provided between the outer periphery of the case 500 and the inside of the case 500.
0a is formed. An air escape groove 500b is formed inside the case 500 at a position facing the plunger 17b, and the air escape groove 500b communicates with the gap 500a. The case 500 has an air escape hole 500.
c is formed, and the air escape hole 500c is
And the air is moved in and out by moving the plunger 17b.

The plunger 17b has an impact pressing surface 17b1 which is the end of the impact extension element 17 in contact with the fuel and is larger than the cross section of the end 17a1 of the impact extension element body 17a. Body 17a
This is a separate component, and is provided at the fuel-side end of the impact extension element body 17a. The shock-extending element main body 17a is composed of, for example, a piezoelectric element, a magnetostrictive element, or a piezoelectric element and a magnetostrictive element connected in series or in parallel. By using the impact extension device 17 in the high pressure generator 16 as a high pressure pump, an impact high pressure can be generated, and atomization of fuel spray can be made possible.

The end 1 of the shock-elongating element main body 17a
By using the plunger 17b having the impact pressure surface 17b1 larger than the cross section 7a1, it is possible to obtain a greater impact pressure with a simple configuration and supply fuel. Further, the shock-extending element body 17 is formed by a piezoelectric element, a magnetostrictive element, or the like.
Since a is formed, the voltage waveform and the current waveform to be applied can be controlled to improve the fuel measurement accuracy and the dynamic range.

The plunger 17b has an annular recess 1
7b2 is formed, and the sealing member 10 for partitioning the shock-elongating element main body 17a side and the pressure chamber 32 into the recess 17b2.
2 is provided. The seal member 102 is formed of an O-ring or a mechanical seal, and the position of the seal member 102 is provided in the middle of the plunger 17b.

By using an O-ring or a mechanical seal as the seal member 102, the stroke length of the plunger 17b can be sufficiently ensured with respect to the stroke and the amount of deformation of the shock-elongating element body 17a, and the reaction force is the fuel pressure and the friction force. No extra force is applied. Further, even when the case main body 31 is thermally deformed, the displacement amount of the working stroke is only the displacement of the shock-elongating element 17a, and thus does not affect the measurement accuracy. Further, the degree of freedom of the shape of the pressurizing chamber 32 is high, and in this embodiment, the pressurizing chamber wall 32a has a funnel shape.

As described above, the plunger 17b is supported by the main body 31 via the sealing member 102,
Numeral 2 separates the shock-extending element main body 17a from the pressurizing chamber 32 with the plunger 17b as a boundary. In the pressurizing chamber 32, there is provided a biasing means 103 for constantly biasing the plunger 17b toward the impact-stretching element main body, and the biasing means 103 is constituted by a spring.

A fuel discharge port 33 is opened at the end of the case body 31 on the side opposite to the shocking pressurizing surface 17b1 for applying a shock high-pressure wave to the pressurized chamber fuel, facing the pressurizing chamber 32. A fuel pipe 15 communicating with the injector 14 is connected to the discharge port 33 via a cap nut 34. The high pressure fuel injection passage 15a is formed by the internal passage of the fuel pipe 15 and the discharge port 33 at the end thereof.
Is configured.

The shock-elongating element 1 serving as a shock high-pressure source
7 is connected to the control circuit 18 (FIG. 1) by a lead wire 30 via a sealing material 29. A side surface of a cylindrical main body 31 orthogonal to the shock-pressing surface 17b1 of the shock-elongating element 17;
That is, the pressure regulating port 35 is opened on the side surface perpendicular to the traveling direction in which the high-pressure wave propagates, facing the pressure chamber 32. The return pressure pipe 35 is connected to the pressure control port 35 via a cap nut 36 and the fuel tank 22 (FIG. 1) via the pressure control valve 101 described above.

In the fuel injection device having such a configuration,
In a state where the fuel is filled in the pressurizing chamber 32, the shock-extending element main body 17 a of the shock-expanding high-pressure source, that is, the shock-expanding element 17
When a drive voltage is applied to the device, a shocking high-voltage wave is generated at the moment when the shape of the shock-elongating element body 17a changes.

The action of generating the high-pressure wave is as follows. First, at each moment of voltage application for a piezoelectric element or at the start of current supply for a magnetostrictive element, the shock-elongating element body 17a changes shape, and the plunger 17b is pushed against the urging means 103, and the shock-pressing surface 17b1 Moves to the pressure chamber side. This instantaneous movement presses the fuel particles in the pressurizing chamber 32, but the fuel particles try to maintain a stationary state by inertia, so that a large pressure is impulsively applied to the fuel in the pressurizing chamber 32. Therefore, this shocking high-pressure wave is applied to the opposing funnel-shaped opposite surface 32 of the pressure chamber 32 in a direction normal to the shocking pressure surface 17b1 from the shocking pressure surface 17b1.
The light is instantaneously propagated from a to the fuel discharge port 33 at a further opposite position. The pressure wave passes through the pressure adjusting port 35 which opens to the side surface of the pressure chamber while traveling in the pressure chamber 32, and the opening direction of the pressure adjusting port 35 is perpendicular to the traveling direction of the high pressure wave. Therefore, the pressure of the high-pressure wave that passes through it instantaneously has substantially no effect on the fuel in the pressure regulating port 35 and the fuel in the fuel supply pipe 21 communicating therewith, and the energy of the high-pressure wave is not consumed.

An impulsive high-pressure source or impulsive extension element 17
The impulse high-pressure wave that has reached the opposing opposite surface 32a of the cylindrical case body 31 from the impulsive pressurizing surface 17b1 enters the fuel discharge port 33 formed solely on this surface, and the fuel in the injection passage 15a And propagates toward the injector 14 via the medium. At this time, the fuel discharge port 33
Since the passage closing member such as the check valve does not intervene, the energy of the high pressure wave enters the fuel injection passage 15a without being consumed. The impulsive high-pressure wave that has reached the injector 14 opens the injection valve 25 against the spring 26 and injects high-pressure fuel from the injection port 41 as described above.

When the expanded shock-extending element main body 17a contracts, the end of the shock-expanding element main body 17a is released from the plunger 17b and contracts, and the plunger 17b is moved by the urging means 103 later than the contraction of the plunger 17b. I do.

FIG. 3 is a diagram showing the course of the pressure fluctuation when the impact extension element is extended. In FIG. 3, p0 indicates an absolute pressure of 0 atm, and p1 is a value immediately before the elongation operation is started and is given by the pressure regulating valve 101. That is, p1
Indicates a pre-pressure state by the pressure of each part of the fuel discharge port 33 and the injection valve 25 of the injection port 41, p2 indicates the valve opening pressure of the injection valve 25 of the injector 14, and p3 indicates the fuel vapor pressure.

The pressure waveform shown in the left direction shows the plunger 17b caused by the shock-extending element body 17a as time elapses.
How the fuel in contact with it shows pressure fluctuations,
The cycle T of the pressure fluctuation is related to the preload P1, and becomes shorter as the preload P1 is higher. If this pressure waveform is moved rightward with the passage of time, the pressure state of each part is known, and the moving speed becomes the sound speed.

In this embodiment, the elongation speed is as shown in FIG. 3 and the first impact pressure (pw1) is large, but the first sparse pressure (nw1) does not become lower than the fuel vapor pressure p3. That is, no bubbles are generated.

Here, when the shock-elongating element body 17a is a piezoelectric element, the strength of the electric field, that is, the applied voltage, and in the case of the magnetostrictive element, the larger the strength of the magnetic field, that is, the larger the field coil current, the larger the expansion value L. Become. The extension speed is the extension value L,
In the case of a piezoelectric element, it is divided by the time t4 until applied charging or in the case of a magnetostrictive element, by the time t4 until the field coil current is maximized. As (pw1) becomes larger, the first sparse pressure (nw1) becomes smaller. For this reason, in the case of a piezoelectric element, when the applied voltage is large or the time t4 until the applied charging is short, and when the elongation speed is increased, bubbles are generated.

FIG. 4 is a diagram showing the course of pressure fluctuation when the shock-elongating element is contracted. In FIG. 4, p0 indicates an absolute pressure of 0 atm, and p1 is a value immediately before the start of the extension operation and is provided by the pressure regulating valve 101. That is, p1
Indicates a pre-pressure state by the pressure of each part of the fuel discharge port 33 and the injection valve 25 of the injection port 41, p2 indicates the valve opening pressure of the injection valve 25 of the injector 14, and p3 indicates the fuel vapor pressure.

The pressure waveform shown in the left direction shows how the plunger 17b by the shock-stretching element shows a pressure change with the elapse of time, and the cycle T of this pressure change is related to the preload P1. Higher the shorter.

If this pressure waveform is moved rightward with the passage of time, the pressure state of each part can be known, and the moving speed is the speed of sound. Here, in the case where the shock-elongating element body 17a is a piezoelectric element, when the intensity of the electric field, that is, the state of the maximum applied voltage is changed from the state of the maximum applied voltage to the state of the zero applied voltage by the discharge at the time t4, the shock-elongating element body 17a is only L It contracts at the speed L / t4. Similarly, when the shock-elongating element main body 17a is a magnetostrictive element, when the strength of the magnetic field, that is, the field coil current is maximized and the current is set to 0 at time t4, the shock-elongation element body 17a moves by the speed L / L. It contracts at t4.

As shown in FIG. 4, when the contraction speed is large L / t4, the first sparse pressure becomes lower than the vapor pressure p3 of the fuel and bubbles are generated, but the first impact pressure (pw) generated thereafter.
1) can be increased.

As described above, the propagation of the pressure wave from the plunger 17b to the fuel discharge port 33 of the pressurizing chamber 32 and each part of the injector 14 is such that the first impact pressure pw1, the first sparse pressure nw1, and the first 2 impact pressure pw2, second negative pressure nw
Propagation proceeds in order of 2.

When the first impact pressure pw1 reaches the injector 14, injection is started, and the fuel pressure is reduced.
The injection ends when the pressure drops below the valve opening pressure. Shortly thereafter, the first depressurization nwl arrives and this first depressurization nw
1 is reflected by the closed injector 14 and propagates in the opposite direction.

Similarly, when the pressure is propagated to each part, the first sparse pressure nw1, the first impact pressure pw1, and the second sparse pressure nw during contraction.
2 and the second impact pressure pw2 propagates in order. The first low pressure nw1 arrives at the injector 14, and the first low pressure nw1 is reflected by the closed injector 14 and propagates in the opposite direction. The first impact pressure pw1 propagating in the valve direction of the injector 14 attenuates due to interference, and becomes smaller before reaching the valve of the injector 14, and becomes smaller.
When the pressure is smaller than the valve opening pressure p2, the injection becomes impossible.

As described above, the plunger 17b gives an impact force to the fuel by the extension of the impact extension element main body 17a, so that the fuel can be injected at an impact high pressure and the atomization of the spray can be made possible. Further, the expanded shock-elongating element body 17a is extended.
Is contracted, the end of the shock-elongating element body 17a is released from the plunger 17b and contracts, and the plunger 17b
Is moved by the urging means 103 later than the contraction of the shock-elongating element main body 17a, the bubbles generated in the fuel can be prevented, and the shortage of output at high speed due to the bubbles can be prevented. Sufficient engine output can be demonstrated from high speed or from low load to high load.

Further, in the fuel injection device of this embodiment, as shown in FIG. 2, the cross-sectional area of the injection passage 15a is made smaller than the cross-sectional area S1 of the pressurizing chamber 32, and the fuel discharge port 33 to the injection passage 15a is The continuous pressurizing chamber wall 32a is formed in a tapered shape, and the impact pressurizing surface 1 of the plunger 17b is formed.
The high impact pressure generated by 7b1 can be collected in the injection passage 15, the high impact pressure reaching the injection valve 25 can be further increased, and fuel can be injected at a high pressure. Further, even if bubbles are generated in the pressurizing chamber 32 due to the low pressure generated in the vicinity of the shocking pressurizing surface 17b1, the bubbles can be smoothly guided from the pressurizing chamber 32 to the injection passage 15a. Therefore, the bubbles can be more reliably crushed and eliminated by the fuel pressure supplied from the fuel supply passage 600 to the injection passage 15a. Further, a check valve may be provided in the fuel supply passage 600. In this case, the first impact pressure (pw1) can be prevented from dissipating into the fuel supply passage 600. Can be reliably prevented from decreasing. That is, sufficient output of the engine can be exhibited from low speed to high speed or from low load to high load by preventing the output from being insufficient due to bubbles.

FIG. 5 is a basic configuration diagram of another embodiment of the present invention. In this embodiment, the fuel supply device 550
A fuel supply pipe 21 for supplying fuel from the fuel supply pipe 21 is connected to the injection passage 15a in the same manner as in the above-described embodiment.
Even if bubbles are generated in the pressurizing chamber 32 due to the fuel pressure, when the bubbles flow into the injection passage 15a, the bubbles can be reliably crushed and disappear.

The return fuel pipe 23 is connected to the pressurizing chamber 32, and a predetermined preload p 1 is applied to the pressurizing chamber 32 by the pressure regulating valve 101.

The fuel supply device 550 includes a fuel tank, a pump and a filter for pumping the fuel, and a gas-liquid separation means including an air bleed for removing bubbles and the like. When the fuel supply device 550 includes, for example, a fuel tank having an air bleed and a fuel pump, the fuel tank constitutes a gas-liquid separation unit.

The injector 14 communicates with the pressurizing chamber 32 via the fuel discharge port 33 and the injection passage 15a as in the above-described embodiment. In this case, as described above, the injector 14 may be of a separated type connected via a fuel pipe, or, as described later, the same valve means as the injector 14 may be integrally provided on the high-pressure generator side. It may be an integrated type that constitutes one unit.

In this embodiment, the plunger 17b
As shown in FIG. 5 (a),
And is arranged so as to face the fuel in the pressurizing chamber 32. In addition, a seal member 102 for separating the shock-extending element main body 17a from the pressurizing chamber 32 with the plunger 17b as a boundary is disposed. As shown in FIG. 5 (b), the shock expanding element body 17a is expanded by charging the shock expanding element 17, which is a shock high voltage source, and contracted by discharging, and the discharging time t11 is made longer than the charging time t10. ing.

As described above, the plunger 17b and the impact extension element main body 17a are integrated,
By charging the shock-elongating element body 17a, the plunger 17b applies an impact force to the fuel by charging the fuel, and the fuel can be injected at an impressive high pressure to enable atomization of the spray. Further, the plunger 17b moves immediately when the shock-elongating element main body 17a expanded by the discharge of the shock-elongating element 17 contracts, but the discharge time t11 is set longer than the charging time t10. The traveling speed of the engine becomes slower and bubbles generated in the fuel can be prevented, and the bubbles do not cause a shortage of output at high speed, and sufficient engine output from low to high or from low to high load can be provided. Can demonstrate.

FIG. 6 is a schematic configuration diagram of an embodiment of the fuel injection device. In this embodiment, the fuel is directly guided from the fuel tank 22 by the fuel pump 19 and sent to the fuel injection unit 44. The return fuel pipe 23 from the fuel injection unit 44 is connected to the upper part of the fuel tank 22.

The high pressure generator 16 and the injector 14
The fuel injection unit 44 is integrally formed as a unit.
Has a compact structure with good fuel injection responsiveness. The injector 14 has a case main body 24 having an injection port 41 formed at the tip, and an injection valve 25 is attached to the injection port 41. The injection valve 25 is always urged by the spring 26 in the closing direction. This injector 14 has
It is connected to the case main body 31 via the case 200 and is integrated therewith. In the injector 14, when the shocking high-pressure wave propagates, it collides with the inner surface of the injection valve 25, and the pressure is further increased. Then, the fuel is injected by pushing the injection valve 25 open against the spring 26 by the energy.

The pressurizing chamber 50 is formed inside the case body 31. On one end side of the pressurizing chamber 50, a storage chamber 43 in which a shock extension element 17 including a shock extension element body 17 a and a plunger 17 b is formed by the case 400 and the case body 31 is provided. And generates an impulsive high-pressure wave in the pressurization chamber 50 to apply impulsive pressure to the fuel in the pressurization chamber 50.

The plunger 17b is arranged so as to be releasable from the end 17c of the shock-extending element main body 17a and to face the fuel in the pressurizing chamber 50. Plunger 17
b has an impact pressure surface 17b1 larger than the cross section of the impact extension element main body 17a, and the fixed end portion 17c is a separate component from the impact extension element body 17a, and the fuel-side end of the impact extension element body 17a. It is press-fitted and fixed to the part. The shock-elongating element main body 17a is composed of a piezoelectric element.

An annular concave portion 17b2 is formed on the outer periphery of the plunger 17b. The concave portion 17b2 is provided with a seal member 102 for partitioning the storage chamber 43 and the pressurizing chamber 50 on the impact expansion element main body 17a side. . Seal member 102
Is composed of an O-ring or the like, and the position of the seal member 102 is
It is provided in the middle of the plunger 17b.

Further, the stroke length of the plunger 17b can be sufficiently ensured with respect to the stroke and the amount of deformation of the shock-elongating element main body 17a, and the reaction force is due to the fuel pressure and the frictional force, so that no extra force is applied. Also, the cylindrical case body 31
Even when the thermal deformation occurs, the displacement amount of the working stroke is only the displacement of the shock-elongating element main body 17a, and thus does not affect the measurement accuracy. Further, the degree of freedom of the shape of the pressurizing chamber 50 is high. In this embodiment, the inner wall 5
0a is funnel-shaped.

A fuel discharge port 33 opens to the pressurizing chamber 50 on the pressurizing chamber wall 50a on the side facing the shocking pressurizing surface 17b1 for applying the high-pressure wave to the pressurizing chamber fuel. This fuel discharge port 33 communicates with the injector 14.

The shock-elongating element 1 which is a shock high-voltage source
7 is fixed to the case 400 by a nut 403 for tightening an end portion. 40
Reference numeral 1 denotes a stopper for preventing the impact-stretching element body 17a from rotating when the nut is tightened. The shock-elongating element 17 is connected to the case main body 31 via the case 400 and is integrated therewith. The shock-extending element main body 17a is connected to the power supply control circuit 18 (FIG. 1) by a lead wire 30. Fuel discharge port 33
The fuel inlet 46a is open on the side surface of the case body 31 near to the pressure chamber 50, that is, on the side surface perpendicular to the traveling direction in which the high-pressure wave propagates. The first branch supply side fuel passage 21a communicating with the fuel supply pipe 21 is connected to the fuel inlet 46a. A check valve 21a1 backed up by a spring is disposed at an upstream portion near the fuel inlet 46a.

Also in this embodiment, the cross-sectional area S2 of the injection passage 33a is made smaller than the cross-sectional area S1 of the pressurizing chamber 32, and the first branch supply side fuel passage 21a is connected to the injection passage 33a, so that the injection passage 33a is separated from the injection passage 33a. The fuel can be supplied. In this way, the fuel in the pressurizing chamber 50 is pressurized by applying the impact force to the fuel in the pressurizing chamber 50 by extending the shock-extending element main body 17a and by the plunger 17b.
The injection valve 25, which is a valve means, is opened to inject fuel by the fuel pressure through the injection port 41 through a. However, bubbles may be generated due to the expansion of the impact expansion element main body 17a in a short time. Even if bubbles are present, the injection passage 33a
And the bubbles are crushed and disappeared by the fuel pressure supplied from the fuel supply passage, which is the first branch supply side fuel passage 21a, to the injection passage 33a. Therefore, the bubbles generated in the fuel can be reduced, and the bubbles can be reduced. It is possible to prevent a shortage of output at high speed due to the cause, and to exhibit sufficient engine output from low to high speed or from low to high load.

Further, since the inner wall 50a of the pressurizing chamber 50 connected to the fuel discharge port 33 to the injection passage 33a of the pressurizing chamber 50 is formed in a funnel shape, air bubbles are smoothly transferred from the pressurizing chamber 50 to the injection passage 3a.
3a, from the fuel supply passage to the injection passage 33.
The bubbles can be more reliably crushed and eliminated by the fuel pressure supplied to a. In addition, since the first branch supply side fuel passage 21a is provided with the check valve 21a1, a decrease in fuel pressure in the injection passage 33a is prevented, so that bubbles can be more reliably crushed and eliminated.

Further, a fuel outlet 47 a opens on the side surface of the case body 31, facing the pressurizing chamber 50. A first branch return-side fuel passage 23a communicating with the return fuel pipe 23 is connected to the fuel outlet 47a. The pressure regulating valve 23 backed up by a spring is located upstream of the fuel outlet 47a.
a1 is arranged.

In the fuel injection device having such a configuration,
In a state where the fuel is filled in the pressurizing chamber 50, the shock-extending element main body 17 of the shock-expanding element 17 which is a shock high-pressure source is generated.
When the drive voltage starts to be applied to the shock-absorbing extension element body 1
At the moment when the shape of 7a changes, an impulsive high-pressure wave is generated in the fuel immediately adjacent to the impressive pressurizing surface 17b1.

The shock high-pressure wave is applied to the shock pressing surface 17b.
From the first side, in the direction normal to the impact pressing surface 17b1,
It is instantaneously propagated toward the fuel discharge port 33 at the position opposite to the pressurizing chamber 50 on the opposite side. This pressure wave is applied to the pressure chamber 5
0, a fuel inlet 46a opening to the side of the pressurizing chamber while proceeding inside
However, since the opening direction of the fuel inlet 46a is obliquely backward with respect to the traveling direction of the high-pressure wave, the fuel inlet 46a instantaneously passes through the opening, and the pressure of the high-pressure wave is applied to the fuel in the fuel inlet 46a and the pressure regulating valve 23a1. On the other hand, there is practically no action, and the energy of the high pressure wave is hardly consumed. Shock extension element 17
The impulse pressure surface 17b1, which is collected by the funnel-shaped pressurization chamber wall 50a, and further pressurized, the impulse high pressure wave enters the fuel discharge port 33 formed solely on this surface, and the injection passage 33a The high-impact high-pressure wave that has reached the opening of the injection valve 25 against the spring 26 causes the injection port 41 to inject high-pressure fuel.

The fuel inlet 46 is provided at one end of the case 400.
A second branch supply side fuel passage 21b communicating with the fuel supply pipe 21 is connected to the fuel inlet 46b. The other end of the case 400 has a fuel outlet 47.
A second branch return-side fuel passage 23b communicating with the return fuel pipe 23 is connected to the fuel outlet 47b. The case 400 is provided with a seal member 190 at a position outside the fuel outlet 47b so that the fuel in the storage chamber 43 does not leak to the outside.

As described above, in this embodiment, the supply side of the fuel circulation path K is connected to the first branch supply side fuel passage 21a and the second branch supply side fuel passage 21a.
The first branch supply fuel passage 21a is branched into a branch supply fuel passage 21b, and the first branch supply fuel passage 21a communicates with the pressurizing chamber 50 via a check valve 21a1 and a fuel inlet 46a.
Is connected to the storage chamber 43 through the fuel inlet 46b. On the other hand, the return side of the fuel circulation path K is branched into a first branch return side fuel passage 23a and a second branch return side fuel passage 23b, and the first branch return side fuel passage 23a is pressurized through a pressure regulating valve 23a1 and a fuel outlet 47a. The second branch return-side fuel passage 23b communicates with the pressure chamber 50 via the fuel outlet 47b.
It is connected to 3. As described above, the fuel circulation path K is branched into a path for supplying fuel to the pressurizing chamber 50 and a path for supplying fuel to the storage chamber 43. Therefore, the fuel circulation path K is shock-extended with a simple structure without a special cooling device. The element body 17a can be cooled, and the pressure chamber 5a is controlled by the pressure regulating valve 23a1.
The excess pressure in the pressure chamber 0 can be made constant, and the fuel can be prevented from flowing back into the storage chamber 43 when the fuel in the pressurizing chamber 50 is shockedly pressurized, thereby further improving the fuel injection accuracy.

In this embodiment, the plunger 17b is pressed by the extension of the shock-extending element body 17a, and the plunger 17b moves against the urging means 103 to give an impact force to the fuel, and the fuel is subjected to an impact high pressure. And can atomize the spray. When the expanded shock-extending element main body 17a contracts, the end of the shock-expanding element main body 17a is connected to the plunger 17 via the fixed end 17c.
The plunger 17b is released from the position b and contracts, and the plunger 17b is moved by the urging means 103 later than the contraction of the impact extension element main body 17a. At this time, the moving speed of the plunger 17b is reduced, so that bubbles generated in the fuel can be prevented, so that the shortage of output at high speed due to the bubbles is prevented.
Sufficient engine output can be exhibited from low speed to high speed or from low load to high load.

FIG. 7 is a detailed configuration diagram around an impact extension element 17 which is an impact high-pressure generating source of another embodiment of the fuel injection device. Fuel injection unit 44 of this embodiment
The high-pressure generator 16 and the injector 14 are integrated, and the storage case 43 is
Is provided, and the shock-elongating element 17 is stored in the storage chamber 43.

A fuel inlet 46 and a fuel outlet 47 are provided in the sealed case 71. Fuel from the fuel supply pipe 21 is supplied from the fuel inlet 46 to the storage chamber 43, and fuel from the storage chamber 43 is returned from the fuel outlet 47. It is returned to the fuel pipe 23. As described above, the storage chamber 43 for storing the impact extension element 17 is provided in the middle of the fuel circulation path K, and the fuel is circulated in the storage chamber 43.

Storage room 43 for storing the shock-elongating element 17
By circulating the fuel, the impact extension element 17 can be cooled with a simple structure without providing a special cooling device. Therefore, the temperature does not rise even if the shock-elongating element 17 is used for a long time, so that the displacement characteristic of the shock-elongation element 17 does not change and the fuel injection accuracy is improved.

The shock-elongating element 17 includes a plurality of piezoelectric elements 7 constituting the shock-elongated element provided in the closed case 71.
3, between the piezoelectric elements 73, the first polar plate 151a and the second polar plate 151b are alternately arranged. The piezoelectric element 73, the first polar plate 151 a, and the second polar plate 151 b are sandwiched between the holder 74 and the hammer 154 in a stacked state, and fixedly held by the bolt 72.

The plunger 15 faces the hammer 154.
2 is disposed, and the plunger 152 has an annular recess 152.
b is formed, and the impact extension element 17 is
A seal member 153 for partitioning the pressure chamber 50 from the side is provided. The seal member 153 is formed of an O-ring or a mechanical seal, and the position of the seal member 153 is provided at an intermediate portion of the plunger 152.

As described above, the plunger 152 is supported by the sealed case 71 via the sealing member 153, and the sealing member 153 separates the impact extension element 17 from the pressurizing chamber 50 with the plunger 152 as a boundary. In the pressurizing chamber 50, there is provided an urging means 103 for constantly urging the plunger 152 in the direction of the high-pressure impact source, and this urging means 103 is constituted by a spring.

As shown in FIG. 7B, a fuel groove 154a is formed radially from the center of the hammer 154. A fuel passage is formed between the hammer 154 and the plunger 152 by the fuel groove 154a.
The plunger 152 is easily released from the hammer 154 when contracting.

The piezoelectric element 73 integrally fixed and held by the bolts 72 is mounted in the closed case 71 by the screw member 75 via the holder 74. The first polar plates 151a and the second polar plates 151b are connected to each other by a conductive plate 76, and are connected to a voltage regulator 302 via a first charge supply line 303 and a second charge supply line 304. Each charge supply line 303 from the sealed case 71,
A grommet 77 for sealing is attached to the take-out portion of 304, and the sealing property in the case is maintained. The sealing grommet 77 further contributes to preventing fuel leakage. The voltage regulator 302 is connected to the ECU 95 and is driven and controlled as described later. Reference numeral 300 denotes an AC power supply, and 301 denotes an AC / DC conversion circuit.

Here, the piezoelectric element is a known piezoelectric actuator composed of an element having a so-called piezoelectric effect. Note that there are various kinds of materials having a piezoelectric effect, from quartz to polymers, and a typical material for a piezoelectric actuator is lead zirconate titanate (PZT), which is a kind of piezoelectric ceramics.

The plunger 152 has an impact-pressing surface 15 larger than a cross section of the piezoelectric element 73 constituting the impact-expanding element.
2a, the plunger 152 is a separate component from the hammer 154, and is provided at the fuel-side end of the piezoelectric element 73.
By using the plunger 152 having the impact pressing surface 152a larger than the cross section of the piezoelectric element 73, it is possible to obtain a higher impact pressure with a simple configuration and supply fuel efficiently.

A plurality (7 in this example) of piezoelectric elements (piezoelectric ceramics) 73 and a first electrode plate 151a and a second electrode plate 151 which are arranged so as to sandwich them and are integrated with each other
b forms an electrostrictive element. An AC current from the AC power supply 300 is converted into a DC voltage via the AC / DC conversion circuit 301 and input to the voltage regulator 302. Voltage regulator 30
2 is controlled by the ECU 95 and the first charge supply line 30
Among the two outputs respectively connected to the third charge supply line 304 or the second charge supply line 304, the first charge supply line 303 side is adjusted to a predetermined positive voltage while the second charge supply line 30 is adjusted.
Ground the 4 side. Alternatively, while the first charge supply line 303 is grounded, the second charge supply line 304 is adjusted to a predetermined positive voltage, or both the first charge supply line 303 and the second charge supply line 304 are grounded. Or

As described above, the fuel injection unit 44 includes the pressurizing chamber 50 communicating with the liquid fuel supply source through the fuel inlet.
The piezoelectric element 73 includes a first electrode on one side of at least one piezoelectric body and a second electrode on the other side, and a plurality of the piezoelectric elements 73 are arranged.
Terminal TA1 on the third side and terminal TA on the second charge supply line 304 side
2, the terminal TA1 has a predetermined positive voltage value, and the terminal TA2
When the voltage is applied to ground the first electrode plate 151a
, An electric field is generated in the direction of the second electrode plate 151b, that is, in the direction of the solid arrow, and the piezoelectric ceramic between the first electrode plate 151a and the second electrode plate 151b expands substantially in proportion to the magnitude of the electric field. On the other hand, when the first charge supply line 303 side is grounded and the second charge supply line 304 side is set to a predetermined positive voltage, the second electrode plate 1
An electric field is generated from 51b in the direction of the first polar plate 151a, that is, in the direction of the dashed arrow, and the first polar plate 151a and the second polar plate 151 are generated.
The piezoelectric ceramic during b shrinks substantially in proportion to the magnitude of the electric field.

In FIG. 7, since the first polar plates 151a and the second polar plates 151b are alternately arranged, the directions of the electric fields acting on the respective piezoelectric ceramics are reversed by 180 degrees in the order of the arrangement of the piezoelectric ceramics. For this reason, in this embodiment, the same plate-shaped piezoelectric ceramics are arranged by inverting the front and back sides by 180 degrees in the order of arrangement.
All the piezoelectric ceramics can be simultaneously expanded or contracted in accordance with the voltage load on the 03 side and the second charge supply line 304 side. The displacements of the respective piezoelectric ceramics are integrated (in FIG. 7, seven displacements are integrated) to be a large displacement.

In order to prevent erroneous assembly, two colors are applied to the outer periphery of the side surface of the same piezoelectric element 73, and arrows extending in the same direction as the direction of the electric field when the piezoelectric element 73 of one color is extended. Are attached to the outer periphery of the side surface, and arrows in the same direction as the direction of the electric field when the piezoelectric element 73 of the other color contracts are attached to the outer periphery of the side surface. Then, by sequentially arranging the different colors in order, and assembling the arrows so as to point in a predetermined direction, it is possible to surely invert and arrange the piezoelectric elements 73 by 180 degrees in the arrangement order. Become.

In this embodiment, the extension of the piezoelectric element 73 causes the hammer 154 to hit the plunger 152, the plunger 152 moves against the urging means 103, and the shock-pressing surface 152a applies an impact force to the fuel. An impulsive high-pressure wave is generated to inject fuel at an impressive high pressure, thereby enabling atomization of the spray. When the expanded piezoelectric element 73 contracts, the end of the hammer 154 is
2, the plunger 152 contracts and the piezoelectric element 7
3 is moved by the urging means 103 later than the contraction of 3. At this time, the moving speed of the plunger 152 is reduced, and bubbles generated in the fuel can be prevented. Thus, the shortage of output at high speed due to the bubbles can be prevented. High engine output.

FIG. 8 is a sectional view of a fuel injection unit according to still another embodiment of the fuel injection device. In the fuel injection unit 44 of this embodiment, the high-pressure generator 16 and the injector 14 are integrated, and a pressurizing chamber 50 is formed by the case main body 71 a of the high-pressure generator 16 and the case main body 24 of the injector 14.

The high-pressure generator 16 includes a case body 71a.
And a lid 71b, a storage chamber 43 is provided.
The shock-extending element 17 serving as a shock high-voltage generating source is housed in the shock-extending element 3 and includes an impact-stretching element main body 17a. The shock-extending element main body 17a has a configuration using a magnetostrictive element. This magnetostrictive element includes a magnetic field generating coil 80, a magnetostrictive member 79 (for example, made of a ternary alloy of terbium, dysprosium, and lead) which is arranged at the center and expands and contracts with respect to a magnetic force in a magnetic field. It consists of The magnetostrictive member 79 expands and contracts by controlling the amount of current (for example, voltage and current) to the magnetic field generating coil 80.

A magnetic field generating coil 8 is provided around the magnetostrictive member 79.
0 is wound, and a cylindrical iron core 84 is mounted around it. The iron core 84, the lid 71b, and the plunger 17b are made of a rigid silicon plate, and constitute a magnetic circuit together with the magnetostrictive member 79. Thereby, the leakage magnetic flux to the outside from the case main body 71a can be eliminated, and a large magnetic field can be generated at the center of the magnetic field generating coil 80. And the magnetostrictive member 7
One end of 9 is fixedly fastened to the lid 71b by a bolt 600, and the plunger 152 can be released from the other end of the magnetostrictive member 79.

The plunger 152 is arranged to face the fuel in the pressurizing chamber 50, and the plunger 152 is
The urging means 152b is always urged in the direction of being retracted from the pressurizing chamber 50 by the action of 52b, and the urging means 152b is constituted by a spring.
The magnetic field generating coil 80 has first and second terminals TA1, TA
2, the first and second terminals TA1 and TA2 are connected to the sealing grommet 67.
7 to prevent the fuel from leaking to the outside.

The plunger 152 has an impact pressure surface 152a larger than the cross section of the magnetostrictive member 79 constituting the impact elongation element main body 17a. The plunger 152 is a separate component from the magnetostrictive member 79. 79 is detachably provided at the fuel side end. By using the plunger 152 having the impact pressure surface 152a larger than the cross section of the magnetostrictive member 79, a greater impact pressure can be obtained with a simple configuration and fuel can be supplied efficiently.

Further, an annular concave portion 152b is formed on the outer periphery of the plunger 152, and the concave portion 152b is provided with a seal member 102 for partitioning the storage chamber 43 on the side of the magnetostrictive member 79 and the pressurizing chamber 50. The seal member 102 is formed of an O-ring or the like, and the position of the seal member 102 is provided in the middle of the plunger 152.

The case body 24 of the injector 14 has
The fuel inlet 46a is formed so as to communicate with the injection passage 33a. The fuel from the fuel supply pipe 21 is supplied from the first branch supply side fuel passage 21a to the check valve 21a1 and the fuel inlet 46a.
Is supplied to the injection passage 33a. Excess fuel from the pressurizing chamber 50 is returned from the return fuel outlet 46 to the return fuel pipe 23 via the pressure regulating valve 180. The inside of the pressurizing chamber 50 can be adjusted to a predetermined fuel pressure by the pressure regulating valve 180,
It has a fuel preload adjustment function.

The case body 24 of the injector 14 has
The fuel inlet 46b is formed, and the fuel inlet 46b is provided with a check valve 181 to prevent the fuel from flowing backward from the storage chamber 43 to the second branch supply side fuel passage 21b. Storage room 43
The pressure chamber 50 communicates with the pressure chamber 50 via a communication hole 170 formed in the case body 71a. The check valve 171 provided in the communication hole 170 communicates with the storage chamber 43 when the fuel pressure in the pressure chamber 50 decreases. Fuel is supplied to the pressurizing chamber 50 from both the fuel inlets 46a.

As described above, the fuel is circulated to the storage chamber 43 for storing the shock-elongating element 17 which is the source of the high-pressure shock, in the middle of the fuel circulation path K.
By circulating the fuel, the impact extension element 17 can be cooled with a simple structure without providing a special cooling device. Therefore, the temperature does not rise even if the shock-elongating element 17 is used for a long time, so that the displacement characteristic of the shock-elongation element 17 does not change and the fuel injection accuracy is improved.

The shock-elongating element main body 17a is provided with a magnetic field generating coil 80 and a case main body 7 which is disposed in a core space of the magnetic field generating coil 80 and one end of which is a unit casing.
1a, a magnetostrictive member 79 which faces the pressurizing chamber 50 via a plunger 152 whose other end is releasable. Of both ends of the magnetic field generating coil 80, a first terminal TA2 is provided with respect to a second terminal TA2. A magnetic field is generated in the core space by receiving power supplied to the terminal TA1 with a positive potential, the magnetostrictive member 79 is extended in a short time, and an impulsive high-pressure wave is generated on the impulsive pressing surface 152a of the plunger 152. Is configured to be injected.

In this embodiment, the plunger 152 is pressed by the extension of the magnetostrictive member 79, and the plunger 152
Moves against the urging means 103 to give an impact force to the fuel, and the fuel can be injected at an impulsively high pressure to enable atomization of the spray. Then, when the elongated magnetostrictive member 79 contracts, the end of the magnetostrictive member 79 is
2, the plunger 152 is moved by the urging means 103 later than the contraction of the magnetostrictive member 79. At this time, the moving speed of the plunger 152 is reduced, and bubbles generated in the fuel can be prevented. Thus, the shortage of output at high speed due to the bubbles can be prevented. High engine output.

The sectional area S2 of the injection passage 33a is made smaller than the sectional area S1 of the pressurizing chamber 50,
The fuel supply pipe 21 and the first branch supply side fuel passage 2
1. The fuel is supplied from the injection passage 33a by communicating with the fuel supply passage 600 including the check valve 21a1, the fuel inlet 46a, and the like. Therefore, the fuel is guided from the pressurizing chamber 50 to the injection port through the injection passage 33a by extending the shock-extending element body 17a and applying an impact force to the fuel in the pressurizing chamber 50 by the plunger 152 to pressurize the fuel. The valve means is opened by the fuel pressure and fuel is injected. However, even if the shock-elongating element main body 17a expands in a short time and air bubbles are generated by the first low pressure after the expansion, the air bubbles are generated. The fuel enters the injection passage 33a from the pressurizing chamber 50,
From the fuel pressure supplied to the injection passage 33a through the fuel inlet 46a, the bubbles are crushed and disappear,
Bubbles generated in the fuel can be reduced, and high-speed output shortage due to the bubbles can be prevented, and sufficient engine output can be exhibited from low speed to high speed or from low load to high load. Note that the cross-sectional area of the fuel-side end of the magnetostrictive member 79 may be made larger than that of the other portions, and an impact pressure may be generated at the end face of the fuel-side end. That is, the end of the magnetostrictive member 79 also serves as a plunger, and the end surface serves as an impact-pressing surface. In this case, the urging means 152
b becomes unnecessary.

FIG. 9 is a schematic configuration diagram showing an embodiment of a power supply device provided in a fuel injection device. Control device 5
00, the crank angle information from the pulsar coil 501 or the crank angle sensor is transmitted to the throttle opening sensor 50.
The throttle opening information from the engine speed sensor 5
03, engine speed information is input. Based on the information, the control device 500 sends a control command to the ignition control circuit 540 according to the ignition control map stored in the memory 510 in advance, and causes the spark plug to spark at the ignition timing according to the operating state of the engine.

Further, the control device 500 controls the charge switch 520 and the discharge switch 521 according to the shock-extending element control map stored in the memory 510 in advance. A predetermined power supply voltage is supplied from the power supply circuit 530 to the terminal TA1 and the terminal TA1 of the shock-absorbing expansion element main body 17a, and the charge switch 520 and the discharge switch 521 are turned on / off at a predetermined timing, thereby causing a shock. The terminal TA1 of the extension element body 17a and the voltage of the terminal TA1 are controlled to extend the impact extension element body 17a at a predetermined timing to inject fuel from the injection port 41 into the combustion chamber 40 of the engine 1.

The shock-extending element body 17 made of a piezoelectric element
In a, by applying a predetermined terminal voltage to the terminal TA1,
The fuel is injected from the injection port 41 into the combustion chamber 40 of the engine 1 by extending the shock-extending element main body 17a.

[0120]

As described above, according to the first aspect of the present invention, the cross-sectional area of the injection passage is made smaller than the cross-sectional area of the pressurizing chamber, and the fuel supply passage is connected to the injection passage so that the injection passage is formed. From the pressurizing chamber through the injection passage by compressing the fuel in the pressurizing chamber by applying impact force to the fuel in the pressurizing chamber by extending or contracting the shock-elongating element, and pressurizing the fuel in the pressurizing chamber by the plunger. The valve means opens at the fuel pressure guided by the mouth to open the fuel and injects fuel. However, a large first impact pressure is generated due to the extension of the impact extension element in a short time,
Subsequently, an extremely large first pressure-elasticity is generated, or an extremely large first pressure-elasticity is generated by contraction of the shock-elongating element in a short period of time, and even when bubbles may be generated, the bubbles may be generated. Since the bubbles enter the injection passage from the pressurizing chamber and are crushed and disappear by the fuel pressure supplied to the injection passage from the fuel supply passage, the bubbles generated in the fuel can be reduced, and the high speed due to the bubbles can be reduced. Insufficient output can be prevented, and sufficient engine output can be exhibited from low speed to high speed or from low load to high load.

According to the second aspect of the present invention, the inner wall of the pressurizing chamber connected to the fuel discharge port to the injection passage of the pressurizing chamber is formed in a funnel shape. Even if bubbles are generated in the pressure chamber, the bubbles can be smoothly guided from the pressurized chamber to the injection passage, and the bubbles are more reliably crushed and disappeared by the fuel pressure supplied from the fuel supply passage to the injection passage. can do.

According to the third aspect of the invention, the check valve provided in the fuel supply passage can more reliably prevent the impact pressure propagating in the injection passage toward the injection valve from dissipating in the fuel supply passage.

According to the fourth aspect of the present invention, since the return fuel pipe for returning the fuel to the fuel supply source side is connected to the pressurizing chamber and the return fuel pipe is provided with the pressure regulating valve, the fuel in the pressurizing chamber is supplied to the predetermined pressure. By doing so, the impact pressure can be further increased, and the difference between the preload value and the fuel vapor pressure value can be increased to make it difficult to generate bubbles.

According to the fifth aspect of the present invention, when the extended shock-elongating element contracts, the plunger is released from the main body of the shock-elongation element, and the plunger is moved by the urging means later than the contraction of the shock-elongation element. At this time, the moving speed of the plunger becomes slower, the first sparse pressure becomes higher than the vapor pressure, air bubbles generated in the fuel can be reduced, and output shortage at high speed due to the air bubbles does not occur. Sufficient engine output can be exhibited from low speed to high speed or from low load to high load.

According to the sixth aspect of the present invention, when the shock-elongating element expanded by the discharge of the shock high-voltage generating source contracts, the discharge time is set longer than the charging time. The moving speed of the part is slowed, the bubbles generated in the fuel can be reduced, and the bubbles do not cause a shortage of output at high speed, and sufficient engine output from low speed to high speed or from low load to high load Can be demonstrated.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a four-cycle internal combustion engine to which a fuel injection device is applied.

FIG. 2 is a detailed configuration diagram of a high-pressure generator and an injector.

FIG. 3 is a diagram showing the course of pressure fluctuation when an impact extension element is extended.

FIG. 4 is a diagram showing the course of pressure fluctuation when the shock-elongating element is contracted.

FIG. 5 is a basic configuration diagram of another embodiment of the fuel injection device.

FIG. 6 is a schematic configuration diagram of an embodiment of a fuel injection device.

FIG. 7 is a detailed configuration diagram around an impact high-pressure generation source according to another embodiment of the fuel injection device.

FIG. 8 is a sectional view of a fuel injection unit according to still another embodiment of the fuel injection device.

FIG. 9 is a schematic configuration diagram showing an embodiment of a power supply device provided in the fuel injection device.

FIG. 10 is a diagram showing the progress of pressure fluctuation when the impact extension element is extended in a short time.

FIG. 11 is a diagram showing the progress of pressure fluctuation when the impact extension element is extended for a long time.

FIG. 12 is a diagram showing the course of pressure fluctuation when the shock-elongating element is contracted in a short time.

[Explanation of symbols]

 Reference Signs List 15a Injection passage 16 High-pressure generator 17 Impact extension element 17a Impact extension element main body 17b Plunger 32 Pressurization chamber 41 Injection port 102 Seal member 103 Energizing means

Claims (6)

[Claims] 1. A pressurizing chamber for pressurizing fuel, an injection port for injecting fuel, an injection passage for guiding fuel from the pressurizing chamber to the injection port, and an impact with an end facing the fuel. A high-pressure pump that shocks the fuel in contact with the end in the pressurized chamber by expanding or contracting the target expansion device, and a high-pressure pump that is provided near the injection port and opens in response to the operation of the high-pressure pump. In the fuel injection device having valve means, the cross-sectional area of the injection passage is made smaller than the cross-sectional area of the pressurized chamber, and fuel can be supplied from the injection passage by connecting the fuel supply passage to the injection passage. A fuel injection device, characterized in that: 2. The fuel injection device according to claim 1, wherein a wall of the pressurizing chamber connected to a fuel discharge port to the injection passage of the pressurizing chamber is formed in a funnel shape. 3. The fuel injection device according to claim 1, wherein a check valve is provided in the fuel supply passage. 4. The pressure chamber is connected to a return fuel pipe for returning fuel to a fuel supply source side, and the return fuel pipe is provided with a pressure regulating valve. A fuel injection device according to claim 1. 5. An end portion of the shock-stretching element is constituted by a plunger detachable from a main body of the shock-stretching element, and a biasing means for constantly biasing the plunger toward the main body of the shock-stretching element. The fuel injection device according to any one of claims 1 to 4, wherein the fuel injection device is provided. 6. The method according to claim 1, wherein said shock-elongating element is expanded by charging a shock high-voltage generating source and contracted by discharging, and a discharging time is made longer than the charging time. A fuel injection device according to any one of the above.