JPH11324850A - Fuel injection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generated bubbles from causing under-output at high speed, and to provide a sufficient engine output from a lower speed to a higher speed, or form a low load to a high load, by expanding an impact expanding element in a short time. SOLUTION: This fuel injection device is equipped with a pressurizing chamber 50 for pressurizing fuel, an injection hole 41 for injecting the fuel, an injection passage 15 for guiding the fuel from the pressurizing chamber 50 to this injection hole 41, a plunger 17b having a tip abutting to the fuel in the pressurizing chamber 50, an energizing means 630 for energizing this plunger 17b in the direction of pressurizing the fuel in the pressurizing chamber 50, a high- pressure generating device which expands an impact expanding element 17 with charge of impressed voltage to move the plunger 17b against the energizing means 630, and shrinks the impact expanding element 17 with discharge of the charged impressed voltage to release the energizing force of the energizing means 630 to allow the plunger 17b to provide impact force for the fuel in the pressurizing chamber 50, and a valve means which is provided near the injection hole and opens responding to the actuation of the high-pressure generating device.

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. 8 and FIG. 9 are diagrams showing the progress of pressure fluctuation when the impact extension element is extended in a short time. 8 and 9, 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,
p3 indicates the fuel vapor pressure.

That is, as the liquid has a lower boiling temperature (boiling point) under the atmospheric pressure, the fuel vapor pressure p3 at a predetermined temperature (the pressure at which the vaporization of the liquid is promoted when the liquid pressure is lower than this pressure) becomes higher. , Easy to evaporate. Conversely, as the liquid has a higher boiling temperature (boiling point) under atmospheric pressure, the fuel vapor pressure p3 at a predetermined temperature becomes lower. If the fuel pressure is not lowered, vaporization is not promoted and vaporization becomes difficult.

[0006] The pressure waveform shown in the left direction shows how the pressure of the fuel in contact with the end changes due to the extension of the shock-extending element over time.

[0007] The liquid fuel particles in contact with the ends are pushed by the ends and move while increasing in density and 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. 8, when the extension speed is particularly fast and the extension 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, if the extension speed is slow and the extension time t2 is long (t2> t1) as shown in FIG. 9, 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. 10 is a diagram showing the course of pressure fluctuation when the impact extension element is contracted in a short time. In FIG. 10, 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 by the pressure of each part, p2 indicates a valve opening pressure of the injector, and p3 indicates a fuel vapor pressure. .

[0011] 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 nw1 is smaller as the contraction speed of the shock-elongating element (contraction distance L divided by contraction time t3, which is equal to the moving speed of the end) is larger. That is, the shorter the contraction time t3 (= movement time of the end), the shorter the contraction distance L
The longer the (= moving distance of the end), the smaller the first pressure-reducing pressure nw1. 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 pw2 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. 8 and 9, the pressure propagation of the pressure wave from the end portion to each part such as the outlet of the pressurizing chamber, the injector, and the like is represented by a first impact pressure pw1 and a first sparse pressure nw1 at the time of extension. ,
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. When the bubble 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. 10 is performed in the order of the first low pressure nw1, the first impact pressure pw1, the second low pressure nw2, and the 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 an impact extension element in a short time, and It is an object of the present invention to provide a fuel injection device that can exhibit a sufficient engine output from high speed or low load to high load.

[0019]

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 is 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, A plunger having a tip portion in contact with the fuel in the chamber, an urging means for urging the plunger in a direction to pressurize the fuel in the pressurizing chamber, and extending the impact extension element by charging of the applied voltage to extend the plunger. Move against the biasing means,
A high-pressure generating device in which the plunger applies an impact force to the fuel in the pressurized chamber by releasing the urging force of the urging means, by contracting the impact expansion element by discharging the charged applied voltage, and near the injection port. And a valve means which is provided in the apparatus and is opened in response to the operation of the high-pressure generator. ].

According to the first aspect of the present invention, the impact extension element is extended by charging the applied voltage, the plunger is moved against the urging means, and the impact extension element is impacted by the discharge of the applied voltage. When the plunger pressurizes the fuel in the pressurized chamber by releasing the urging force of the urging means by contracting the element, the fuel is guided from the pressurized chamber to the injection port via the injection passage, and the valve means is driven by the fuel pressure. Even when the shock-elongating element expands or contracts in a short period of time, the movement of the plunger is slowed down and the first shock pressure is increased,
Subsequently, an extremely small first pressure drop does not occur, and it is possible to prevent bubbles from being generated in the fuel and to prevent a shortage of output at high speed due to the bubbles. To provide sufficient engine output over high loads.

[0022]

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 40.
And a cylinder block 3 constituting a cylinder of the combustion chamber 40
And a crankcase 4 forming a crankcase. A crankshaft 5 in the crank chamber is connected to a connecting rod 100 connected to a crankpin 6 and a piston pin 7.
Is connected to the piston 8. An intake passage 9 is provided in the cylinder head 2, and an intake valve 10 is attached to an end of the cylinder head 2 so as to face the combustion chamber 40, and opens and closes an opening of the intake passage 9. An exhaust passage 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 40, and opens and closes an opening of the exhaust passage 11. A spark plug 13 is mounted at the center of the cylinder head 2.

In this embodiment, a fuel injection unit 44 for directly injecting fuel into the combustion chamber 40 is provided facing the combustion chamber 40 from the upper surface of the cylinder head 2. 9 may be provided to inject fuel, or may be provided to inject fuel from the cylinder block 3 into the cylinder.

In the fuel injection unit 44, the injector 14 and the high-pressure generator 16 are integrated. This high-pressure generating device 16 includes a piezoelectric element of a shock-extending element described later,
A shocking high-voltage generation source including a magnetostrictive element, an element in which a piezoelectric element and a magnetostrictive element are connected in series, and the like are provided. This shock high pressure source is connected to the control device 18 and injects fuel directly into the fuel chamber 40 at a predetermined timing, for example, among the four strokes of explosion expansion, exhaust, intake, and compression, the intake stroke or the compression stroke. Drive control is performed to inject during the stroke.

The fuel injection unit 44 is connected to the fuel tank 22 by the fuel pump 19 through the fuel supply pipe 21.
Fuel is introduced from. A filter 20 is provided at an inlet of the fuel supply pipe 21 in the fuel tank 22. A pressure regulating valve 1 is provided downstream of the fuel supply pipe 21.
01 is provided to apply a pre-pressure to the fuel supplied to the fuel injection unit 44 so as to perform accurate fuel injection. The return fuel pipe 23 is connected to the pressure regulating valve 101, and the return fuel pipe 23 is connected to the fuel tank 22.

While the fuel injection unit 44 is closed, fuel is always supplied from the fuel pump 19 through the fuel supply pipe 21, and the pressure regulating valve 1 disposed in the fuel supply pipe 21 is supplied.
When the pressure on the upstream side of 01 is equal to or higher than a predetermined value, the pressure regulating valve 101 is opened, and the fuel returns to the upper part of the fuel tank side having an air vent hole (not shown) through the return fuel pipe 23 and circulates. A path K is formed.

FIG. 2 is a detailed configuration diagram of the fuel injection unit in the embodiment. 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 high pressure generator 16 and the injector 14 are
The fuel injection unit 44 is integrally formed as a unit.
Has a compact structure with good fuel injection responsiveness.

The unit case 600 includes a case body 60.
An upper case 602 and a lower case 603 are attached to both sides of the device 1. The lower case 603 includes the injector 14
Is assembled. The injector 14 has an upper case 14a and a lower case 14b. Upper case 14
a is assembled to the lower case 603, the nozzle 14c is assembled to the lower case 14b, the injection port 41 is formed in the nozzle 14c, and the injection valve 41 is attached to the injection port 41. The injection valve 25 is a spring. 26 is always biased in the closing direction.

A diaphragm 620 made of a metal plate is provided between the case body 601 and the lower case 603, and the pressure chamber 50 is formed by the diaphragm 620 made of the metal plate and the lower case 603. Fuel of a constant pressure (preload) from the pressure regulating valve 101 is supplied to the pressurizing chamber 50 by the plunger 17b.
The fuel is supplied through the fuel passage 17b1 and the check valve 17c at the center of the fuel cell, and the fuel is guided from the pressurizing chamber 50 to the injection passage 15 through the fuel discharge port 33, and further from the injection passage 15 to the injection port 41. Valve 2 which is a valve means by fuel pressure
5 opens against the spring 26 and fuel is injected.
The fuel discharge port 33 is provided with a check valve 33a, and the check valve 33a is constantly urged in the closing direction by a spring 33b. The valve opening pressure of the injection valve 25 is the pressure regulating valve 101.
Is set higher than the preload pressure by the check valve 33a.
Is set low.

In the unit case 600, there is disposed the shock-extending element 17 which includes the shock-extending element main body 17a and the plunger 17b. The shock-elongating element main body 17a is supported by the insulator bases 610 and 611, the plunger 17b is movably inserted into the insulator base 610, and a stopper 612 is fixed to an end of the plunger 17b. A disc spring as urging means 630 is disposed between the stopper 612 and the upper case 602 to urge the plunger 17b in the direction of pressurizing the fuel in the pressurizing chamber 50, and to move the impact extension element body 17a. One is an insulator base 611 and the other is an insulator base 610.
Is pressed against the case body 601 through the flange portion 610a.

The shock-elongating element 1 as a shock high-voltage source
7 is connected to the control device 18 by a lead wire 30.
a is a piezoelectric element. End 17b2 of plunger 17b
, A diaphragm 620 made of a metal plate is fixed by a nut 631. Fuel is guided from the pressurizing chamber 50 to the injection passage 15 through the fuel discharge port 33,
Then, the fuel is injected into the injection port 41, and the injection valve 25, which is a valve means, is opened against the spring 26 at the fuel pressure to inject fuel.

In the fuel injection device having such a configuration,
The controller 18 applies an applied voltage to the shock-elongating element main body 17a of the shock-elongated high-voltage source, ie, the shock-elongating element 17,
When the impact extension element main body 17a is extended by charging the applied voltage, the plunger 17b is moved by the stopper 612 against the urging means 630.

By the discharge of the applied voltage charged in the shock-extending element body 17a, the shock-extending element body 17a
Is contracted, and the urging force of the urging means 630 is released by the contraction of the shock-extending element main body 17a, and the stopper 612 is released.
Causes the plunger 17b to move. This plunger 1
The fuel in the pressurizing chamber 50 is pressurized by the movement of the tip portion 17b2 of 7b.

By pressurizing the fuel in this way, the check valve 33a of the fuel discharge port 33 is opened, and the fuel is guided to the injection port 41 through the injection passage 15, and the injection valve 25 is opened by the fuel pressure to open the injection port 41. Inject fuel from

In this fuel injection device, even if the shock-elongating element main body 17a expands or contracts in a short time, the urging means 63 can be used.
0 slows down the movement of the plunger 17b, causing a large first
Neither the impact pressure nor the extremely low first sparse pressure is generated, and no bubbles are generated in the fuel. Therefore, it is possible to prevent a shortage of output at high speed due to bubbles, so that sufficient engine output can be exhibited from low speed to high speed or from low load to high load.

FIG. 3 is a schematic configuration diagram showing an embodiment of a power supply device provided in the 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 520 according to an ignition control map stored in the memory 510 in advance, and causes the spark plug to spark at an ignition timing according to the operating state of the engine.

Further, the control device 500 sends a control command to the shock-extending element terminal voltage control circuit 530 when the shock-expanding element main body 17a is a piezoelectric element according to the shock-expanding element control map stored in the memory 510 in advance. Control the charge switch and the discharge switch. A power supply circuit 53 is connected to the terminals TA1 and TA2 of the shock-stretching element body 17a.
1, a predetermined power supply voltage is given, and the charge switch and the discharge switch are turned on / off at a predetermined timing to control the voltages of the terminals TA1 and TA2 of the shock-elongating element main body 17a, thereby to set a predetermined timing. By contracting the shock-elongating element main body 17a from the expanded state in the embodiment of FIG.
Is injected into the combustion chamber 40.

4 to 6 show still another embodiment of the power supply device. FIG. 4 is a circuit diagram of the power supply device, and FIG.
FIG. 6 is a diagram showing a configuration of a generator, and FIG. 6 is a diagram showing a change in charging voltage.

The generator 700 of this embodiment has a structure shown in FIG.
Has a stator 701 and a rotor 702,
The rotor 702 rotates in conjunction with the crankshaft of the engine. The stator 701 includes a charge coil L2 and an ignition charge coil L3, and the rotor 702 includes a permanent magnet 703. Also, the rotor 702 has
A projection 704 is provided, and a pulsar coil L1 is disposed at a position facing the projection 704.

As shown in FIG. 4, the AC output of the ignition charge coil L3 is rectified by the diode D1 of the ignition circuit and charged in the ignition capacitor C1. A thyristor SCR is connected to the ignition capacitor C1, a primary coil L10a of the ignition coil L10 is connected to the thyristor SCR, and an ignition plug 720 of the engine is connected to the secondary coil L10b.

The pulsar coil L 1 outputs an ignition signal when the projection 704 crosses due to the rotation of the rotor 702, that is, at a predetermined reference crank angle, and this ignition signal is input to the control device 500. The control device 500 sends an ignition signal to the ignition thyristor SCR1 of the ignition circuit at an ignition timing delayed by a desired crank angle from the reference crank angle, and the conduction of the ignition thyristor SCR causes the secondary coil L10b of the ignition coil L10 to conduct. A high voltage is generated to cause spark plug 720 to spark.

The AC output of the charge coil L2 is rectified by the diode D2. From the positive electrode of this DC power supply, the positive electrode of the shock-expanding element main body 17a, the negative electrode of the shock-expanding element main body 17a via the shock-expanding element main body 17a, and the negative electrode of the DC power supply from the negative electrode of the shock-expanding element main body 17a. A first closed circuit K1 is formed, and the first closed circuit K1 is formed.
A second closed circuit K2 connecting the positive electrode and the negative electrode of the shock-extending element body 17a is formed in parallel with 1 and a thyristor SCR3 for discharging a shock-expanding element that constitutes a discharge switch in the second closed circuit K2. The first closed circuit K1 is configured to supply the DC power supply itself to the shock-expanding element main body 17a without providing the shock-expanding element charging capacitor. Since the first closed circuit K1 is not provided with a shocking expansion element charging capacitor, the thyristor SCR3 for discharging the shocking expansion element is turned on by the control device 500 with a simple circuit configuration using a DC power supply without using a battery. Under control, the discharge from the shock-extending element body 17a is enabled at a predetermined timing, the shock-extending element body 17a is contracted in response to the rotation of the crankshaft, and the fuel is injected by the urging means 630, and then the next injection is performed. The thyristor SCR3 for discharging the shock-stretching element can be turned off at an appropriate timing to extend the shock-stretching element body 17a.

That is, a voltage as shown in FIG. 6 is generated in the charge coil L2 by one rotation of the engine.

In the embodiment shown in FIG. 2, the shock-extending element main body 17a is extended by charging the applied voltage, and the charging of the applied voltage becomes a predetermined voltage V1 by one rotation of the crankshaft, and the voltage of the next crankshaft becomes one. A predetermined charge voltage V by rotation
In response to this, the impact extension element main body 17a is extended, and the plunger 17b is moved. When the charging voltage V2 of the shock expanding element body 17a is discharged by the operation of the shock expanding element discharging thyristor SCR3, the shock expanding element body 17a contracts, and the urging means 630 is contracted by the contraction of the shock expanding element body 17a. Is released, and the plunger 17b is moved by the stopper 612. By the movement of the plunger 17b, the fuel in the pressurizing chamber 50 is pressurized, and the fuel is injected.

That is, in the case of the four-cycle in-cylinder injection shown in FIG. 1, fuel injection starts during the intake stroke in which the piston descends once every two crankshaft revolutions, or at the beginning of the subsequent compression stroke. The discharge timing is set and controlled so that the fuel injection ends before ignition performed at a predetermined crank angle before the top dead center.

FIG. 7A is a timing chart of the discharge signal and the ignition signal in the two-cycle in-cylinder injection engine. FIG. 7B shows the fuel injection timing at which the shock-extending element main body 17a of the embodiment shown in FIG.

The control device 500 repeats a discharge signal once for every two rotations of the crankshaft and outputs the signal at a predetermined timing, whereby the thyristor SCR for discharging the shock-extending element is discharged.
3 is activated.

In the two-cycle in-cylinder injection engine, after the ignition combustion, the piston exhausts the burned gas from the exhaust port on the side of the cylinder during the descending stroke, while the fresh air guided from the intake passage to the crank chamber is moved downward by the piston. During the stroke, the pressure is increased in the crank chamber, and the pressure is guided into the combustion chamber from a scavenging port on the side of the cylinder which opens after the exhaust port is opened. During the gas exchange of the burned gas in the cylinder with fresh air by the exhaust and scavenging, the fuel starts to be directly injected into the cylinder from the injection port 41 of the embodiment of FIG. The injection is ended before the ignition timing at a predetermined crank angle before the top dead center.

That is, as shown in FIG. 7A, E is a period when the exhaust port is open, S is a period when the scavenging port is open, and both the exhaust port and the scavenging port are open. During this period, after the piston enters the ascent stroke, a discharge signal is transmitted to the shock-extending element main body 17a. Although the shock-elongating element main body 17a contracts immediately due to the discharge, as shown in FIG. 7B, the plunger 17b has inertia, and the fuel in the pressurizing chamber 50 is pressurized with a very short time t1. Fuel injection is started. The injection is continued while the fuel pressure in the pressurizing chamber 50 is higher than the sum of the valve opening pressure of the injection valve 25 and the combustion chamber pressure during the period in which the plunger 17b is moved by the urging force of the urging means 630.

[0051]

As described above, according to the first aspect of the present invention, the impact extension element is extended by charging the applied voltage to move the plunger against the urging means, and the charged applied voltage is reduced. The discharge expands the shock-stretching element and releases the biasing force of the biasing means, causing the plunger to exert a shocking force on the fuel in the pressurized chamber, and injecting the fuel from the pressurized chamber by setting the fuel to a high pressure. It is guided to the injection port through the passage and the valve means opens with fuel pressure to inject fuel,
Even if the shock-elongating element expands or contracts in a short time, the movement of the plunger is delayed, so that a large first shock pressure and a very small first sparse pressure are not generated, and bubbles are generated in the fuel. Can be prevented and insufficient output at high speed due to air bubbles can be prevented, so that sufficient engine output can be exhibited from low speed to high speed or from low load to high load.

[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 fuel injection unit.

FIG. 3 is a schematic configuration diagram showing an embodiment of a power supply device provided in the fuel injection device.

FIG. 4 is a circuit diagram of a power supply device.

FIG. 5 is a diagram showing a configuration of a generator.

FIG. 6 is a diagram showing a change in charging voltage.

FIG. 7 is a diagram showing a timing chart of a discharge signal and an ignition signal and a fuel injection timing.

FIG. 8 is a diagram showing the progress of pressure fluctuation when the impact extension element is extended in a short time.

FIG. 9 is a diagram showing the progress of pressure fluctuation when the impact extension element is extended for a long time.

FIG. 10 is a diagram showing the course of pressure fluctuation when the shock-elongating element is contracted in a short time.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 15 Injection path 16 High-pressure generator 17 Impact extension element 17a Impact extension element main body 17b Plunger 17c Incompressible fluid 41 Injection port 50 Pressurizing chamber 630 Energizing means

Claims (1)

[Claims] 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 a tip portion in contact with the fuel in the pressurizing chamber. A biasing means for biasing the plunger in the direction of pressurizing the fuel in the pressurizing chamber, and a shock-extending element which is stretched by charging of the applied voltage to push the plunger against the biasing means. A high-pressure generating device for causing the plunger to move the fuel, pressurize the fuel in the pressurized chamber by releasing the urging force of the urging means by contracting the shock-expanding element by discharging the charged applied voltage, and A fuel injection device comprising: valve means provided near an injection port and opened in response to operation of the high-pressure generator.