JPH10184498A - Fuel injection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To atomize the spray of the fuel by injecting fuel at an impact high pressure using an impact stretching element and to feed the fuel by generating a higher impact pressure through a simple constitution. SOLUTION: A fuel injection device comprises a pressure chamber 32 communicated with a fuel feed source; a low pressure pump arranged on a fuel feed route running from the fuel feed source to the pressure chamber 32; an injection nozzle 41 to inject the fuel; an injection passage to guide the fuel from the pressure chamber 32 to the injection nozzle 41; an injection passage to guide the fuel from the pressure chamber 32 to the injection nozzle 41; a high pressure pump to pressurize fuel in the pressure chamber 32 by an impact force by stretching the impact stretching element 17a having a plunger 17b arranged at a tip part making contact with fuel; and a valve means arranged in the vicinity of the injection nozzle and having a valve means opened in correspondence to operation of the high pressure pump. The area of the impact pressure surface of the plunger 17b is larger than that of the impact stretching element 17a.

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 Applicants have disclosed a fuel injection device as disclosed in Japanese Patent Application No. Hei.
No. 219672 proposes a fuel injection device for injecting fuel at a high pressure into a combustion chamber of an internal combustion engine. This fuel injection can be injected at an impressive high pressure, which is advantageous in atomizing the spray. By using a shock-expanding element such as a piezoelectric element or a magnetostrictive element in the vibration (pressure) source portion of such a fuel injection device, the fuel can be shocked to a high pressure with a relatively simple structure and atomization of the spray can be obtained. Can be.

[0003]

By the way, in the structure using such an impact elongating element, the impact pressing surface of the plunger for applying an impact force to the fuel by the impact elongating element has a cross section of the impact elongating element. It is the same size, and there is a problem that it is difficult to generate a larger impact pressure by operating the plunger.

[0004] The present invention has been made in view of the above-mentioned point, and makes it possible to inject fuel at an impulsively high pressure by using an impulsively extending element to atomize the spray, and to increase the impulsive pressure with a simple structure. It is an object of the present invention to provide a fuel injection device that can supply fuel.

[0005]

According to a first aspect of the present invention, there is provided a fuel injection device, comprising: a pressurizing chamber communicating with a fuel supply source; and a fuel supply source. A low-pressure pump provided on the fuel supply path to the pressurizing chamber, an injection hole for injecting fuel, an injection passage for guiding fuel from the pressurizing chamber to the injection hole, and a tip portion in contact with the fuel. A high-pressure pump for pressurizing the fuel in the pressurized chamber by an impact force by extending an impact-elongating element provided with a plunger; and valve means provided near the injection hole and opened in response to the operation of the high-pressure pump. Wherein the impact-pressing surface of the plunger is larger than the cross section of the impact-stretching element.

[0006] By using an impact extension element in a high pressure pump, fuel can be injected at an impact high pressure, and atomization of spray can be made possible. Also, by using a plunger having an impact pressure surface larger than the cross section of the impact extension element,
With a simple configuration, a greater impact pressure can be efficiently obtained and fuel can be supplied.

The fuel injection device according to a second aspect of the present invention is characterized in that the plunger is provided with a seal member for partitioning the shock-extending element side and the pressurizing chamber. The position of the seal member is, for example, in the middle of the plunger,
It is provided at a joint or the like between the plunger and the fuel-side end of the piezoelectric element or the magnetostrictive element. By using a sealing member,
It is possible to prevent the fuel from leaking to the outside.

[0008]

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. 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 pipe 9 is provided in the cylinder head 2, and an intake valve 10 is attached to an end of the cylinder pipe 2 so as to face the combustion chamber, 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, and opens and closes an opening of the exhaust pipe 11. A spark plug 13 is mounted at the center of the cylinder head 2.

In this embodiment, an injector 14 for directly injecting fuel into the combustion chamber is provided facing the upper side of the cylinder head 2 into the combustion chamber. 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. This high-pressure generating device 16 includes a piezoelectric element of a shock-extending element described later,
An impact high-voltage source 17 is provided which includes a magnetostrictive element, a piezoelectric element and a magnetostrictive element connected in series, and a plunger. The shock high voltage source 17 is connected to a control circuit 18 and is driven and controlled at a predetermined timing.
The high pressure generator 16 is connected to a fuel tank 22 via a fuel supply pipe 21 by a fuel pump 19 which is a low pressure pump.
Fuel is introduced from. A filter 20 is provided at an inlet of the fuel supply pipe 21 in the fuel tank 22. The injector 14 is connected to a pressure release pipe / air release pipe 23, and the air release pipe 23 is provided with a pressure regulating valve 101 for adjusting the pressure. If air is present, accurate injection cannot be performed.
Is provided to remove the air. However, because of the presence of the air release pipe 23, it is not possible to apply a stable residual pressure to the downstream portion including the high-pressure generator 16, so the pressure regulating valve 101 is provided to adjust the pressure. And perform accurate fuel injection.

[0010] The discharge pressure of the low-pressure pump is always constant 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 hole in the injector 14 to further increase the pressure. Make it possible. In addition, part of the shocking high pressure wave
When the air bubbles reach 1, the air bubbles also pass through the pressure regulating valve 101.

FIG. 2 shows a high-pressure generator 1 according to the embodiment.
FIG. 6 is a detailed configuration diagram of an injector 6 and an injector 14. The injector 14 comprises a case body 24 having an injection hole 41 at the tip, and a valve 25 is mounted on the injection hole 41. Valve 25
Is always urged in the closing direction by the spring 26. The fuel pipe 15 is connected to the injector 14 via a cap nut 27. An air vent port 28 is formed on the side wall of the case body 24, and the air vent port 2
8 is connected to an air release pipe 23. The air bleeding port 28 is provided not on the position facing the traveling direction of the shocking high-pressure wave but on the side surface in the traveling direction. Propagation in the direction. Air release port 28
Are formed in the case body 24 and the high-pressure generator 16
Can discharge bubbles in a wide range up to the pressure chamber 32.

As will be described later, the injector 14
When the shocking high-pressure wave propagates, it collides with the inner surface of the valve 25 and further rises in pressure. The energy pushes the valve 25 open against the spring 26 and fuel is injected.
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 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 valve 25 is opened and fuel is injected. Further, the spring 26 opposes the discharge pressure of the fuel pump 19, so that air bubbles are removed during the operation of the fuel pump 19.
Can be discharged to

The high-pressure generator 16 has, for example, a cylindrical main body 3.
1 and a pressure chamber 32 is formed therein. On one end side of the pressurizing chamber 32, an impact high-pressure source 17 including an impact extension element 17a, a plunger 17b, and the like is mounted. This shocking high pressure source 17
Is to generate an impulsive high-pressure wave in the pressurizing chamber 32 to apply impulsive pressure to the fuel in the pressurizing chamber 32.

The plunger 17b is provided with an impact extension element 17
a, the plunger 17b is a separate component from the impact extension element 17a, and is provided at the fuel-side end of the impact extension element 17a. The impact extension element 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 17a 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. Further, by using the plunger 17b having the impact pressure surface 17b1 larger than the cross section of the impact extension element 17a, it is possible to obtain a greater impact pressure with a simple configuration and supply the fuel. Further, since the shock-stretching element 17a is formed by a piezoelectric element, a magnetostrictive element, or the like, the applied voltage waveform and the current waveform can be controlled to improve the fuel measurement accuracy and the dynamic range.

The plunger 17b has an annular concave portion 1.
7b2 is formed, and a seal member 102 is provided in the concave portion 17b2 for partitioning the impact expansion element 17a side and the pressurizing chamber 32. 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 secured with respect to the stroke and the deformation amount of the impact extension element 17a, and the reaction force depends on the fuel pressure and frictional force. No extra force is applied. Further, even when the cylindrical main body 31 as a case undergoes thermal deformation, 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. In addition, the degree of freedom of the shape of the pressurizing chamber 32 is high, and the air hardly accumulates.

The cylindrical main body 3 on the side opposed to the shock-pressing surface 17b1 for applying a shock high-pressure wave to the pressurized chamber fuel.
At one end, a fuel discharge port 33 is opened facing the pressurizing chamber 32. A fuel pipe 15 communicating with the injector 14 through a cap nut 34 is connected to the discharge port 33.
Is connected. The high pressure fuel injection passage 1 is formed by the internal passage of the fuel pipe 15 and the discharge port 33 at the end thereof.
5a is configured. The impulsive high-voltage source 17 is connected to a control circuit 18 (FIG. 1) by a lead wire 30 via a sealing material 29.
Linked to Impact pressure surface 1 of impact high pressure source 17
On the side surface of the tubular main body 31 orthogonal to 7b1, that is, the side surface perpendicular to the traveling direction of the high-pressure wave, a fuel introduction port 35 opens toward the pressurization chamber 32. The fuel supply port 35 is connected to the fuel supply pipe 21 communicating with the above-described fuel pump 19 (FIG. 1) via a cap nut 36.

In the fuel injection device having such a configuration,
When a drive voltage is applied to the shock expanding element 17a of the shock high pressure source 17 while the pressurizing chamber 32 is filled with fuel, a shock high voltage wave is generated at the moment when the shock expanding element 17a changes its shape. . The action of generating this high-pressure wave is as follows. First, the shock-elongating element 17a changes its shape at each moment of voltage application in the piezoelectric element or the start of current supply in the magnetostrictive element, and the shock-pressing surface 17b1 of the plunger 17b.
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, the shocking high-pressure wave instantaneously travels from the shocking pressing surface 17b1 side to the fuel discharge port 33 at a position opposite to the pressing surface 32 in the direction perpendicular to the shocking pressing surface 17b1. Propagate. This pressure wave passes through the fuel introduction port 35 which opens to the side surface of the pressurization chamber while traveling in the pressurization chamber 32. Since the opening direction of this port 35 is perpendicular to the direction of travel of the high-pressure wave, The pressure of the high-pressure wave that passes through it instantaneously has substantially no effect on the fuel in the fuel introduction port 35 and the fuel in the fuel supply pipe 21 communicating therewith, and the energy of the high-pressure wave is not consumed at all. Therefore, the fuel introduction port 35 may be provided with an opening blocking means such as a check valve. However, even without this, the impact high pressure does not dissipate so much. The fuel introduction port 35 is connected to the impact pressurizing surface 17b1.
It may not be located in front, and may be arranged so as to face the inside of the pressurizing chamber 32 in parallel with the impact high-pressure source 17.

Impulsive pressing surface 17 of impulsive high-pressure source 17
The high-pressure shock wave reaching the opposite end face of the cylindrical main body 31 from b1 is the only fuel discharge port 3 formed on this face.
3 and propagates toward the injector 14 through the fuel in the injection passage 15a. At this time, since a passage closing member such as a check valve is not interposed in the fuel discharge port 33, 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 valve 25 against the spring 26 and injects high-pressure fuel from the injection hole 41 as described above.

In this embodiment, 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. Instead, as shown in the injector 14a shown by a dashed line, , May be provided in the middle of the intake pipe 9. 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. Further, in the above-described embodiment, the air vent pipe 23 connects the fuel tank 22 as the gas-liquid separating means to the fuel tank 14, but instead of this structure, as shown by a dashed line 23a in FIG. , The injector 14 and the high-pressure generator 16 may be arranged to communicate with each other. Thereby, the fuel pipe 15
And, the air and the fuel vapor in the injector 14 are discharged into the combustion chamber together with the fuel injection. Then, even after the air is injected and discharged by a plurality of injections, the fuel vapor generated by vaporization due to the heat propagation from the combustion chamber remains in the injector 14 even after the valve 25 is closed in addition to the discharge into the combustion chamber. The residual pressure allows the fuel vapor to return to the cold pressurized chamber 32 far from the combustion chamber and be condensed. In this case, the pressurizing chamber 3 is used instead of the illustrated air vent pipe 23.
A return pipe connecting the fuel tank 2 and the fuel tank 22 is provided, and a pressure regulating valve is provided in the middle of the return pipe.

FIG. 3 is a block diagram of another embodiment of the high-pressure shock source. In this embodiment, a reflecting surface R is formed on the inner surface of the pressurizing chamber 32, the high-pressure wave from the high-impact high-pressure source 17 is reflected by the reflecting surface R to change the direction, and is introduced into the fuel discharge port 33. is there. Accordingly, the high-pressure wave traveling path from the shocking pressing surface 17b1 in the pressing chamber 32 becomes a broken line path bent at the reflecting surface R as shown by L in FIG. The polygonal path changes depending on the angle, position, or number of the reflecting surfaces R, and the desired layout can be obtained by changing the relative positions of the high-impact high-pressure generation source 17 and the fuel discharge port 33. The other configuration including the injector 14 and the operation and effect are the same as those in the embodiment of FIG. 2 described above.

FIGS. 4A, 4B and 4C are diagrams each showing a basic configuration of another embodiment of the present invention. In each embodiment, fuel is supplied from the fuel supply device 550 to the pressurizing chamber 32 via the fuel supply pipe 21 and the fuel introduction port 35. The fuel supply device 550 includes a fuel tank, a pump and a filter for pumping the fuel, and a gas-liquid separation unit 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. Air release pipe 23
Is connected to the upper part of the fuel tank,
Air bubbles mixed in the fuel returning to the fuel tank are separated in the fuel tank.

Alternatively, as another example, the fuel supply device 55
0 includes a float chamber provided in a fuel supply pipe connecting the fuel tank and the fuel pump. The float chamber is configured such that when the fuel decreases due to the float and the needle valve provided therein, the float lowers and opens the needle valve to introduce the fuel, thereby keeping the liquid level in the float chamber constant. . An air bleed hole is provided in this float chamber to release steam and air. When the fuel supply source has such a float chamber, the float chamber constitutes a gas-liquid separation unit. In this case, the air vent pipe 23 is connected to the upper part of the float chamber or to a fuel supply pipe between the fuel tank and the float chamber. This allows
Air bubbles mixed in the fuel returning to the air release pipe 23 are separated in the float chamber, and only the fuel flows from the float chamber to the fuel pump. 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, the injector 14 may be of a separate type connected via a fuel pipe as described above, or as described later, a valve means similar to the injector may be provided integrally on the high-pressure generator side, and It may be an integrated type comprising three units.

4A, the air vent port 28 is connected to the pressurizing chamber 32 and the injector 1 serving as valve means.
The air vent pipe 23 connected to the air vent port 28 communicates with the gas-liquid separation means of the fuel supply device 550. Is provided. (B)
Has a configuration in which an air vent port 28 is provided above the pressurizing chamber 32 and communicates with the gas-liquid separating means, and a pressure regulating valve 101 is provided on the fuel supply device 550 side. (C) shows a configuration in which an air vent port 28 is provided in the injector 14 as a valve means, which is connected to the gas-liquid separation means, and a pressure regulating valve 101 is provided on the injector 14 side. (A),
By increasing the volume of the air vent pipe 23 upstream of the pressure regulating valve 101 as shown in (B), more air from the pressurizing chamber 32 can be guided into the air vent pipe 23 upstream of the pressure regulating valve 101. Therefore, it is possible to make it difficult for the air to stay in the pressurizing chamber 32 and to reduce the relaxation of the impact pressure due to the air in the middle of the propagation. Further, by attaching the pressure regulating valve 101 directly to the fuel supply device 550 or the high pressure generating device 16 as shown in FIGS.
Books and can be minimized.

FIG. 5 is a detailed configuration diagram of the regulating valve. FIG.
The pressure regulating valve 101 shown in FIG. 4 is configured as shown in FIG. The pressure regulating valve 101 is, for example, a metal housing 1.
The interior is divided into a spring chamber 101d and a fuel chamber 101e by a rubber diaphragm 101c. Fuel enters through the inlet 101f, fills the fuel chamber 101e, and fills the diaphragm 101c.
The spring 101h pushes the valve 101g through the
Balances spring force at set pressure. Fuel exit 101
It is returned to the fuel supply side via i. The spring chamber 101d of the regulating valve 101 is communicated with the outside air so as to always maintain a constant set pressure with respect to the atmospheric pressure.

FIG. 6 shows another example of the configuration of the injector.
The injector 14 in FIG. 6A is of an external valve type in which the injector opens outward as in FIGS. 2 and 3 described above. An electromagnetic solenoid 60 for driving the valve 25 is provided inside the injection hole 41 formed at the tip of the case body 24. In such a configuration, at the timing when an impulsive high-pressure wave arrives from the high-pressure generator 16, the electromagnetic solenoid is energized to open the valve 25, and fuel is injected from the injection hole 41. The timing of the valve opening is determined in advance by an experiment or the like to determine the time from when the driving voltage is applied to the shocking high-voltage generation source 17 of the high-pressure generator to when the high-pressure wave reaches the injector 14. A control circuit is configured so as to energize the solenoid 60. With such a configuration, since the energy of the high-pressure wave is not consumed for opening the valve, it is possible to inject the fuel with higher injection energy. The electromagnetic solenoid 60 is provided with a notch in the longitudinal direction that communicates the upper part and the lower part in a part of the outer periphery.
It is made to propagate smoothly in the direction. Further, a recess may be provided in the longitudinal direction on the case body 24 side on the outer periphery of the electromagnetic solenoid 60.

The injector 14 shown in FIG.
Unlike the example of (A), the valve is an inward-opening type in which the valve opens inward, and an electromagnetic solenoid 6 for driving the inward-opening valve 4 is provided.
0 is provided. A valve 40 is slidably disposed inside the guide sleeve 37 inside the injection hole 41 formed at the tip of the case body 24. The valve 40 is pressed by the spring 39 toward the injection hole 41 and urged to a closed state. A conduction hole 38 is opened at the base of the guide sleeve 37, and the fuel injection passage 15a in the fuel pipe 15 and the case body 24 are opened.
And the internal combustion passage chamber 24a. Spring 39
Is disposed in the guide sleeve 37 and the sleeve 3
The upper seal member 91 fixed to the base 7 and a seal ring (not shown) at the lower end are mounted in a sealed space in which fuel is prevented from entering. An air vent port 28 is opened in the case main body 24 and communicates with the above-mentioned fuel tank 22 (FIG. 1) through an air vent pipe 23. In such a configuration, a high-pressure shock wave is propagated from the high-pressure generator 16 side through the fuel in the injection passage 15a, and the injector 1
4, high-pressure energy is introduced into the case body 24 through the through hole 38, and the valve 40 is moved to the spring 3.
Then, the fuel is injected by opening the injection hole 41. The shocking high-pressure wave is guided to the conduction hole 38 without being attenuated by the conical portion on the upper part of the sealing member 91, and the conduction hole 38
From the fuel passage chamber 24a having a cylindrical shape. The shocking high-pressure wave collides with the wall of the fuel passage chamber 24a and
Increase pressure at the top. The second shocking high-pressure wave propagates from the booster toward the injection hole 41 in the lower portion of the fuel passage chamber 24a. The air vent port 28 is provided on the intermediate side wall of the fuel passage chamber 24a, so that the energy of the second shock high-pressure wave does not dissipate.

The structure and operation of the electromagnetic solenoid 60 are the same as those in the example of FIG. 6A. In this example, since the energy of the high-pressure wave is not consumed for opening the valve, the fuel fuel is supplied with a large injection energy. Can be fired. The electromagnetic solenoid 60 faces the outlet of the passage hole 38 on the fuel passage chamber 24a side. Then, the injection hole 41 is provided by the electromagnetic solenoid 60.
Since the air vent port 28 is provided on the side, air can be vented to a portion closer to the injection hole 41. In addition,
The electromagnetic solenoid 60 may be used to forcibly close the valve 40 at a predetermined timing to prevent impulsive high-pressure waves from pulsating in the fuel passage 15 resulting in inaccurate metering. .

FIG. 7 is a detailed block diagram of a high-voltage shock source using a piezoelectric element. The impact high-pressure source 17 has a plurality of piezoelectric elements 73 provided in a closed case 71,
Between each piezoelectric element 73, a positive electrode plate 15la and a negative electrode plate 151 are provided.
b are alternately arranged. The piezoelectric element 73, the positive electrode plate 15la and the negative electrode plate 15lb are sandwiched between the holder 74 and the plunger 152 in a stacked state, and
2 fixedly hold each other. Thus, the bolt 72
The piezoelectric element 73 integrally fixed and held by the above is mounted in the closed case 71 by the screw member 75 via the holder 74. Each positive electrode plate 15la and the negative electrode plate 15
lbs are connected to each other by a conductive plate 76 and connected to a voltage regulator 302 via a positive charge supply line 303 and a negative charge supply line 304. A sealing grommet 77 is attached to a portion where each of the charge supply lines 303 and 304 is taken out from the sealed case 71 to maintain the hermeticity of the case. 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 made 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 elongating element.
2a, the plunger 152 is a separate component from the piezoelectric element 73, and is provided at the fuel-side end of the piezoelectric element 73. By using the plunger 17b having the impact pressing surface 152a larger than the cross section of the piezoelectric element 73, it is possible to obtain a greater impact pressure with a simple configuration and supply fuel efficiently.

Further, an annular concave portion 152b is formed on the outer periphery of the plunger 152, and the piezoelectric element 7 is formed in the concave portion 152b.
There is provided a seal member 153 for partitioning the pressure chamber 32 from the third side. The position of the seal member 153 is
Is provided in the middle part of. By using the sealing member 153, the stroke length of the plunger 152 is
The stroke and the deformation amount can be sufficiently secured, and the reaction force is due to the fuel pressure and the frictional force, so that no extra force is applied. Further, even when the sealed case 71 is thermally deformed, the displacement amount of the operation stroke is only the displacement of the piezoelectric element 73, and thus does not affect the measurement accuracy. Further, the seal member 153 can prevent the fuel from leaking from the high pressure generator 16 to the outside. The sealing grommet 77 further contributes to preventing fuel leakage. The seal member 153 separates the piezoelectric element 73 from the fuel, and prevents the piezoelectric element 73 from being corroded by water mixed in the fuel due to dew condensation or the like in the fuel tank 22.

In FIG. 7, a plurality of sheets (seven sheets in this example)
The piezoelectric element (piezoelectric ceramic) 73 and the positive electrode plate 151a and the negative electrode plate 15lb which are arranged so as to sandwich them form 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. The voltage regulator 302 is controlled by the ECU 95 and adjusts the positive charge supply line 303 side of the two outputs connected to the positive charge supply line 303 or the negative charge supply line 304 to a predetermined positive voltage. On the other hand, the negative charge supply line 3
Ground the 04 side. When lowering the voltage of the positive electrode plate 15la, a part of the electric charge of the positive electrode plate 15la is grounded. The piezoelectric ceramic between the positive electrode plate 15la and the negative electrode plate 15lb is displaced in the direction of the electrode plates in substantially proportion to the magnitude of the electric field generated by the two electrode plates. This displacement is 7 in FIG.
And the displacement becomes large.

FIG. 8 is a configuration diagram of another embodiment of the high-pressure shock source. This embodiment has a configuration using a magnetostrictive element instead of the above-described piezoelectric element. This magnetostrictive element
Magnetoelectric materials that expand and contract in a magnetic field, such as terbium,
It is composed of a magnetic core using a ternary alloy of dysprosium and lead, and a coil wound around the outer periphery of the magnetic core. The magnetic core expands and contracts by controlling the amount of current (for example, voltage and current) to the coil. 8, a coil 80 is wound around a magnetostrictive element 79, and a permanent magnet 84 is mounted around the coil 80. A plunger 152 is fixed to an end of the magnetostrictive element 79. The plunger 152 is constantly urged by the action of the spring 82 in the direction of being pulled from the pressurizing chamber 32. The coil 80 is connected to a voltage regulator via a lead 78.

The plunger 152 has an impact-pressing surface 15 larger than a cross section of the magnetostrictive element 79 constituting the impact-expanding element.
2a, the plunger 152 is a separate component from the magnetostrictive element 79, and is provided at the fuel-side end of the magnetostrictive element 79. By using the plunger 17b having the impact pressing surface 152a larger than the cross section of the magnetostrictive element 79, a large impact pressure can be obtained with a simple configuration and fuel can be supplied efficiently.

The plunger 152 has a recess 152b.
Is formed, and a seal member 153 for partitioning the piezoelectric element 73 side and the pressure chamber 32 is provided in the concave portion 152b. The position of the seal member 153 is provided in the middle of the plunger 152. By using the seal member 153, the stroke length of the plunger 152 can be sufficiently secured with respect to the stroke and the amount of deformation of the magnetostrictive element 79, and the reaction force is due to the fuel pressure and the frictional force, so that no extra force is applied. Further, even when the sealed case 71 is thermally deformed, the displacement amount of the working stroke is only the displacement of the magnetostrictive element 79, and thus does not affect the measurement accuracy. The cross-sectional area of the fuel-side end portion of the magnetostrictive element 79 may be larger than that of the other portion, and L may be generated so as to generate an impact pressure at the end surface of the fuel-side end portion. That is, the end of the magnetostrictive element 79 also serves as a plunger, and the end surface serves as a shocking pressure surface. In this case, the seal member 153 cannot contribute to the prevention of corrosion of the end of the ground strain element 79, but does not prevent the corrosion of the inside of the magnetostriction element 79, and even if the sealing grommet 77 is deteriorated, the fuel is not removed. Leakage to the outside can be prevented.

The voltage regulator is connected to the ECU similarly to the above-described example, and controls the drive current to the coil 80 to control the magnetostrictive element 7.
Adjust the applied voltage to 9. When the drive voltage of the coil 80 is increased, the drive current flowing through the coil 80 is also increased, and the magnitude of the magnetic field generated by the coil is increased.
The applied voltage to 9 becomes large, and a large shocking high-pressure wave is generated. Other configurations and operational effects are the same as those of the embodiment using the piezoelectric element. In driving the magnetostrictive element 79, a current regulator may be arranged in place of the voltage regulator, and a large current may be applied to the coil 80 in a stepwise manner while maintaining a constant voltage. Further, one end of the magnetostrictive element 79 may be fixed to the end plate of the sealed case 71 with bolts or the like, and the spring 82 may be omitted.

FIG. 9 is a graph showing the relationship between the impulsive high voltage generated by the high voltage generator according to the present invention and the driving signal. Graph a shows a pressure waveform, and graph b shows a drive signal. In the graph a, P1 indicates the valve opening pressure of an injector having an external or internal valve, and P0 indicates the pressure in the pressurizing chamber before pressurization. As shown in the figure, immediately after the drive signal is turned on, a high pressure that greatly exceeds the valve opening pressure is generated in an impact, and then rapidly attenuates. Each of the above embodiments is
The impulsively high pressure immediately after the input of the drive signal is effectively propagated and used in the fuel. Further, as shown in the drawing, immediately after the drive signal is turned off, the pressure waveform temporarily decreases and the pressure increases due to the reaction of the vibration, and a pressure wave exceeding the valve opening pressure P1 is generated. Such a pressure peak when the drive signal is off can be propagated to the injection hole as an impact pressure as in the case of on and used for fuel injection. In addition,
In a device using a piezoelectric element as shown in FIG. 7 for the high voltage generator, the drive signal is a pulse voltage signal having a voltage value equal to or more than a predetermined value. In the magnetostrictive element shown in FIG. A pulse current signal having a value or a pulse voltage signal having a voltage value equal to or higher than a predetermined value.

FIG. 10 shows a fuel injection device 2 according to the present invention.
An example applied to a cycle internal combustion engine is shown. This engine 1
1 has a piston 8 that slides in a cylinder, similarly to the engine of FIG.
And an exhaust pipe 11 communicating with the combustion chamber 43 in the cylinder. Further, the crank chamber and the combustion chamber 43 communicate with each other through a scavenging passage 42. Throttle valve 4 in intake pipe 9
8 and a reed valve 47 are provided. The cylinder head 2 is provided with a fuel injection unit 44 facing the combustion chamber 43. The fuel injection unit 44 is configured by integrally forming the high-pressure generator 16 and the injector 14 in the above-described embodiment, and injects fuel by using a shocking high-pressure wave as in the above-described embodiment.

The fuel injection unit 44 communicates via a fuel supply pipe 21 with a gas-liquid separation float chamber 46 provided with a breather hole (not shown) at an upper portion provided above the fuel injection unit 44. This gas-liquid separation float chamber 46
Is connected to a fuel tank 2 via a float valve 46a for keeping the liquid level constant, a fuel pump 19A and a filter 20.
Connect to 2. The fuel injection unit 44 is connected to the control circuit 18 similarly to the above-described embodiment, and further connected to a power supply circuit 45 including an AC power supply and an AC / DC conversion circuit. The fuel injection unit 44 may be provided on the side wall surface of the cylinder block 3 or on the intake pipe 9 as shown by the dashed line in FIG.

With this configuration, air bubbles in the pressurizing chamber, the injection passage, and the valve means (not shown) in the fuel injection unit 44 enter the air vent pipe 23 while the engine 1 is stopped, and the float chamber 4
It moves by buoyancy in six directions. The bubbles enter the pressurized chamber because the injection passage is higher than the valve means and the pressurized chamber is higher than the injection passage. The air bubbles enter the air release pipe 23 from the pressure chamber because the opening of the air release pipe 23 on the pressure chamber side is located above the pressure chamber. The opening of the air release pipe 23 on the pressurization chamber side is
If it is higher than an introduction port (not shown) at the end, air bubbles can be surely introduced into the air vent pipe 23. on the other hand,
Bubbles in the fuel supply pipe 21 move into the float chamber 46 by buoyancy while the engine 1 is stopped.

During the operation of the engine 1, the fuel injection unit 4
4 is operated, and the injection by the generation of the high-pressure shock wave, the negative pressure generated in the pressurized chamber by the injection, and the fuel movement to the pressurized chamber by the head (positive pressure) due to the fuel oil level of the float chamber 46 are alternately performed. It occurs continuously. At the time of fuel transfer to the pressurizing chamber, if air bubbles are present in the portion close to the pressurizing chamber in the air releasing pipe 23, the air bubbles will return to the pressurizing chamber again.
If a check valve that allows the flow only in the direction of the float chamber 46 is arranged in the inside 3, the air can be reliably vented even during the operation of the engine 1. Since the shocking high-pressure wave has strong directivity in the normal direction of the generation surface, the amount of fuel pushed out into the air vent pipe 23 during fuel injection (the amount of fuel leakage) is small. Due to this slight fuel pushing action into the air release pipe 23,
The air bubbles in the air vent pipe 23 move to the float chamber 46 without fail and are separated. The amount of fuel pushed back into the fuel supply pipe 21 during fuel injection (the amount of fuel leakage) is small, but if a check valve that allows flow only in the direction of the pressurized chamber is arranged in the fuel supply pipe 21, Injection leakage can be reduced.

The fuel pump 1 is connected to the fuel supply pipe 21.
9B can be provided, and the pressure control valve 101 is provided in the air vent pipe 23. In this case, the gas-liquid separation float chamber 46
Does not require a float type valve 46a for keeping the liquid level constant, but a fuel level meter including an upper limit level sensor S1 and a lower limit level sensor S2 is provided.
When the fuel level of the gas-liquid separation float chamber 46 falls below the position of the lower limit level detection sensor S2, the fuel pump 19A is driven to supply fuel from the fuel tank 22 via the filter 20, and the upper limit level detection sensor S1 supplies fuel. Upon detection, the supply of fuel is stopped.

The engine 1 of this embodiment further uses a fuel injection device to supply oil. An oil injection unit 49 uses the high-pressure generator 16 of the above-described embodiment. Oil is injected from the oil injection unit 49 into the crank chamber and the cylinder from the injector 55 via the oil pipes 53 and 54. Oil is supplied to the oil injection unit 49 from an oil tank 51 via a strainer 52 by an oil pump 50. The oil injection unit 49 has a high-pressure generation source and injects oil from the injector 55 by an impulsively high pressure, as in each of the above-described embodiments. The injection operation is the same as in the above embodiments. The pressurizing chamber is provided with a plurality of lubricating oil discharge boats each communicating with the oil pipe 53 at a position facing one shocking high-pressure generating section. By arranging the above-described air bleeding means also in this fuel injection device, air bleeding can be easily performed.

FIG. 11 is a detailed configuration diagram of the fuel injection unit. In the embodiment of FIGS. 11A, 11B, and 11C, the fuel injection unit 44 has the high-pressure generator 16 and the injector 14 integrally formed as a unit, and has good fuel injection responsiveness and is compact. It has a simple structure. FIG.
The injector 14 of the embodiment shown in FIG. 1A has a case body 24 having an injection hole 41 formed at the tip.
1 is equipped with a valve 25. The valve 25 is always biased in the closing direction by a spring 26. The main body 31 of the high-pressure generator 16 is connected to the injector 14 via a case 200.
Are connected to and are integrated. This injector 14
Then, when the shocking high-pressure wave propagates, it collides with the inner surface of the valve 25 and further rises in pressure. The valve 25 is pushed and opened against the spring 26 by the energy, and fuel is injected.

The high-pressure generator 16 has a pressurizing chamber 32 formed inside a main body 31. At one end of the pressurizing chamber 32, a high-pressure generating source 17 including a shock-extending element 17a, a plunger 17b, and the like is mounted, and a shocking high-pressure wave is generated in the pressurizing chamber 32. Impulsive pressure is applied to the fuel in the pressurizing chamber 32. The plunger 17b has an impact pressing surface 17b1 larger than the cross section of the impact extension element 17a. The plunger 17b is a separate component from the impact extension element 17a, and is press-fitted and fixed to the fuel-side end of the impact extension element 17a. Provided. The impact extension element 17a is composed of, for example, a piezoelectric element, a magnetostrictive element, a piezoelectric element and a magnetostrictive element connected in series or in parallel, and the like.

An annular concave portion 17b2 is formed on the outer periphery of the plunger 17b, and the seal member 1 which partitions the impact extension element 17a side and the pressurizing chamber 32 into the concave portion 17b2.
02. The seal member 102 is configured by an O-ring or a mechanical seal, and the position of the seal member 102 is
It is provided in the middle of the plunger 17b. Seal member 1
By using an O-ring or a mechanical seal as 02, the stroke length of the plunger 17b can be sufficiently secured with respect to the stroke and the amount of deformation of the shock-elongating element 17a as described above, and the reaction force depends on the fuel pressure and frictional force. No extra force is applied. In addition, a cylindrical main body 3 which is a case
Even if 1 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. In addition, the degree of freedom of the shape of the pressurizing chamber 32 is high, and the air hardly accumulates. In this embodiment, the inner wall 32a of the pressurized chamber has a funnel shape.

The fuel discharge port 33 faces the pressurizing chamber 32 at the end of the pressurizing chamber wall 32a on the side facing the shocking pressurizing surface 17b1 for applying the high-pressure shock wave to the pressurizing chamber fuel.
Opens. This fuel discharge port 33 communicates with the injector 14.

The impact extension element 1 of the impact high-voltage source 17
7a is a case 4 with a nut 403 for tightening the end.
00 is fixed. Reference numeral 401 denotes a stopper for preventing the impact extension element 17a from rotating when the nut is tightened. The shock high voltage source 17 is connected to the main body 31 of the high voltage generator 16 via the case 400 and is integrated therewith. Shock extension element 1
7a is connected by a lead 30 to the control circuit 18 (FIG. 1). Impact pressure surface 17b of impact high pressure source 17
A fuel introduction port 35 opens on the side surface of the cylindrical main body 31 orthogonal to 1, that is, on the side surface perpendicular to the traveling direction in which the high-pressure wave propagates, facing the pressurizing chamber 32. The fuel supply port 21 is connected to the fuel supply pipe 21 communicating with the fuel pump 19 (FIG. 1). Fuel introduction port 35
A check valve 21a backed up by a spring is disposed at an upstream portion near the valve, and a pressure regulating valve 23a is disposed at an upstream end of the pneumatic vip 23.

In the fuel injection device having such a configuration,
When the driving voltage is applied or the driving current is started to be supplied to the shock expanding element 17a of the shock high pressure source 17 while the pressurizing chamber 32 is filled with the fuel, the shock expanding element 17
An instantaneous high-pressure wave is generated at the moment when a changes shape. This shock high-pressure wave instantaneously propagates from the shock pressing surface 17b1 side in a direction perpendicular to the shock pressing surface 17b1 toward the fuel discharge port 33 on the opposite surface side of the pressing chamber 32. . This pressure wave passes through the fuel introduction port 35 which opens to the side surface of the pressurization chamber while traveling in the pressurization chamber 32. Since the opening direction of this port 35 is perpendicular to the direction of travel of the high-pressure wave, The pressure of the high-pressure wave that passes through it instantaneously has substantially no effect on the fuel in the fuel introduction port 35 and the fuel in the fuel supply pipe 21 communicating therewith, and the energy of the high-pressure wave is not consumed at all. The high-pressure impulsive wave emitted from the impulsive pressurizing surface 17b1 of the impulsive high-pressure generation source 17, collected by the funnel-shaped pressurized inner wall 32a, and further pressurized is injected into the fuel discharge port 33 formed solely on this surface. And propagates toward the injector 14. The shocking high-pressure wave that has reached the injector 14 opens the valve 25 against the spring 26 and injects high-pressure fuel from the injection hole 41. The air release pipe 23 is connected to the pressurized chamber 32 of the high-pressure generator 16 and the fuel tank 2 serving as a gas-liquid separation unit.
2 can be communicated, and a wide range of bubbles up to the pressurizing chamber 32 can be discharged.

In the embodiment of FIG. 11B, similarly to the embodiment of FIG. 11A, the plunger 17b
Although it has an impact pressure surface 17b1 larger than the cross section of 7a, the plunger 17b is provided by being screwed and fixed to the fuel-side end of the impact extension element 17a with screws 402. The plunger 17b has an impact extension element 17a.
A seal member 102 for partitioning the pressure chamber 32 from the side is provided, and the seal member 102 is formed of a diaphragm. The diaphragm made of a metal plate constituting the sealing member 102 is provided together with the plunger 17b and the impact extension element 17.
a, which is also fastened to the fuel side end by a screw 402, and is provided between the plunger 17b and the impact extension element 17a,
An outer peripheral portion 102a of the diaphragm is fixed to an inner wall of a cylindrical main body 31 which is a case.

In the embodiment shown in FIG. 11C, the plunger 17b is provided with the impact extension element 1 similarly to the embodiment shown in FIG.
Although it has an impact pressure surface 17b1 larger than the cross section of 7a, the plunger 17b is provided to be joined and fixed to the fuel-side end of the impact extension element 17a. Further, the plunger 17b is provided with a seal member 102 for partitioning the shock-elongating element 17a side and the pressurizing chamber 32.
Is composed of a bellows made of a rubber material. One end 102b of the bellows forming the seal member 102 is fixed to the plunger 17b, and the other end 102c is fixed to the cylindrical main body 31 as a case.

Both the seal member 102 made of a diaphragm in FIG. 11B and the seal member 102 made of a bellows in FIG.
11C is disposed on the opposite side of the shock-pressing surface 17b1, and even if each is elastically deformable, the high-pressure generator 16 of FIG.

FIG. 12 shows still another configuration example of the fuel injection unit in the engine of FIG. This fuel injection unit 44 integrates the high-pressure generator 16 and the injector 14 as in FIG. In this example, as shown, a pressurizing chamber 32 having an impact extension element 17a and a plunger 17b of the impact high pressure source 17 is shown.
In addition, an injection hole 41 is provided via an injection passage 96 immediately after a pressurizing chamber 32 having an inner surface 32a serving as a reflection surface R without passing through a fuel pipe. An outward-opening valve 25 is attached to the injection hole 41 via a spring 26. The relative position between the high-pressure source 17 and the discharge port 33 is determined according to the position and angle of the reflection surface R. In this example, there is one reflecting surface R, and the high-pressure wave is reflected only once and introduced into the discharge port 33. In addition, an air vent port 28 is formed in the upper part of the pressurizing chamber 32 to effectively discharge air in the pressurizing chamber. The configuration and operation and effect of the high-impact high-pressure generation source 17, and the operation of propagating the high-pressure wave through the injection passage 96, the fuel injection operation, the air release operation, and the like are the same as those in the above-described embodiment.

[0055]

As described above, in the fuel injection device according to the first aspect of the present invention, the use of the shock-extending element in the high-pressure pump enables the generation of the shock pressure and the atomization of the fuel spray. can do. Further, by using a plunger having an impact pressure surface larger than the cross section of the impact extension element, a greater impact pressure can be obtained with a simple configuration and fuel can be supplied.

In the fuel injection device according to the second aspect of the present invention,
By using a seal member for partitioning the shock-extending element side and the pressurizing chamber for the plunger, it is possible to prevent fuel from leaking to the outside.

[Brief description of the drawings]

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

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

FIG. 3 is a configuration diagram of another embodiment of a high-pressure source.

FIG. 4 is a basic configuration diagram of another embodiment of the present invention.

FIG. 5 is a detailed configuration diagram of a regulating valve.

FIG. 6 is a configuration diagram of another example of the injector.

FIG. 7 is a detailed configuration diagram of a high-voltage generation source using a piezoelectric element.

FIG. 8 is a configuration diagram of another impulsive high-pressure source.

FIG. 9 is a graph of a high voltage shock wave and a drive signal.

FIG. 10 is a configuration diagram of a two-cycle engine to which the fuel injection device according to the present invention is applied.

FIG. 11 is a detailed configuration diagram of a fuel injection unit.

FIG. 12 is a configuration diagram of still another embodiment of the fuel injection unit.

[Explanation of symbols]

 Reference Signs List 16 high-pressure generating device 17 shocking high-pressure source 17a shock-elongating element 17b plunger 17b1 shock-pressing surface 32 pressurizing chamber 41 injection hole

Claims (2)

[Claims] A pressurizing chamber communicating with a fuel supply source; a low-pressure pump provided on a fuel supply path from the fuel supply source to the pressurizing chamber; an injection hole for injecting fuel; An injection passage that guides fuel from the pressurized chamber to the injection hole, and a high-pressure pump that pressurizes the fuel in the pressurized chamber with an impact force by extending an impact-elongating element having a plunger disposed at a tip end in contact with the fuel, A valve means provided in the vicinity of the injection hole, the valve means being opened in response to the operation of a high-pressure pump, wherein an impact-pressing surface of the plunger is made larger than a cross section of the impact-expansion element. Injection device. 2. The fuel injection device according to claim 1, wherein the plunger is provided with a seal member for partitioning the impact extension element side and the pressurizing chamber.