JPH1193799A - Fuel injection valve and fuel injection system using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To gradually extend the combustion while suppressing the initial injection ratio to improve the calmness of engine and reduce NOx by providing a solenoid for electromagnetically driving an armature in the opening direction of a valve needle, and regulating the lift quantity of the valve needle according to the current-carrying quantity to the solenoid. SOLUTION: In a spring chamber 315, a spool valve 308 is regularly energized down through an armature 316. A bobbin 319 having a coil 318 wound thereon is arranged on the circumference of the spring chamber 315, and the coil 318 is excited by current-carrying to generate an attracting force to the armature 316 in a stator 311, whereby a servo valve 308 is driven upward. In the current- carrying, since the attracting force of the stator 311 is increased and decreased according to the current-carrying quantity to the coil 318, the lift quantity of a nozzle needle can be regulated. The combustion is gradually extended while suppressing the regulated initial injection ratio to improve the calmness of engine and reduce NOx.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fuel injection valve and a fuel injection system.

[0002]

2. Description of the Related Art A common rail injection system is known as one of fuel injection systems for injecting fuel into a diesel engine. In the common rail injection system, a common pressure accumulation pipe (common rail) communicating with each cylinder is provided, and a variable discharge high pressure pump is used to supply high-pressure fuel at a required flow rate to thereby keep the fuel pressure in the pressure accumulation pipe constant. keeping. The high-pressure fuel in the pressure accumulation pipe is injected into each cylinder by a fuel injection valve at a predetermined timing (for example, JP-A-64-73166, JP-A-7-2
No. 93387).

FIG. 8 shows an overall vertical cross section of this type of fuel injection valve, and FIG. 9 shows an enlarged cross section of a main part thereof. The fuel injection valve includes a main body 801 and a control electromagnetic valve 802. A cylinder 805 is formed in the nozzle body 803 at the tip of the main body 801, and the fuel injection hole 8 is formed at the tip.
04 is formed. A nozzle needle 806 displaced along the cylinder 805 is provided.
Fuel pumped from the common rail into the cylinder 805 is introduced through the introduction channel 807. This fuel constantly urges the nozzle needle 806 in the valve opening direction in an injection chamber 808 formed around the nozzle needle 806. A biasing force in the valve closing direction by the spring 810 always acts on the nozzle needle 806 via a rod 809 provided above the nozzle needle 806.

A control rod 812 is provided on the upper side of the rod 809 and slides in the guide hole 811 coaxially with the rod 809. At the rear end face of the control rod 812, high-pressure fuel flows from the introduction flow path 807 through a throttle 813. A control chamber 814 to be introduced is formed. The control room 814 is provided with another throttle 815 and the solenoid valve 8.
02 communicates with a discharge passage 819 leading to a low-pressure fuel tank via a valve portion 816.

[0005] The valve portion 816 includes a hemispherical seat portion 817 and a ball 818 serving as a valve body.
The push rod 820 is constantly urged downward (to close the valve) by the spring force of the spring 821. An armature 822 is provided integrally with the push rod 820. Stator 8 provided facing armature 822
When the coil 23 is energized, the armature 822 attracts the armature 822 and the push rod 820 is displaced upward. This causes the ball 818 to lift. on the other hand,
When the power to the coil 824 is released, the push rod 82
0 is displaced downward by the spring force of the spring 821 and the ball 8
18 is seated on the seat portion 817.

When the coil 824 is energized and the valve section 816 is opened, the fuel in the control chamber 814 is throttled 815 and the discharge flow path 819
Through the fuel tank. Here, the cross-sectional area of the restrictor 815 is sufficiently larger than the cross-sectional area of the restrictor 813, and the pressure in the control chamber 814 is reduced to release the force for pushing down the control rod 812, the nozzle needle 806 is opened, and the fuel injection hole is opened. Injection is performed from 804.

When the energization of the coil 824 is stopped again and the valve portion 816 is closed, the pressure in the control chamber 814 becomes high, and the force for pushing down the control rod 812 increases.
The resultant force with the spring force of 10 becomes more dominant than the force acting in the valve opening direction of the injection chamber 808, the nozzle needle 806 closes, and the fuel injection stops.

[0008]

On the other hand, in the case of a fuel injection valve of a jerk type fuel injection system, the pressure of the injection chamber gradually increases with the pressure feed of the plunger of the fuel pump, and the injection rate gradually increases. On the other hand, in a fuel injection valve in which the injection chamber communicates with the common rail, the injection chamber is always at the same high pressure as the common rail, so the nozzle needle valve opening operation rises rapidly, The injection rate can take substantially only a single value.

In a fuel injection system using such a fuel injection valve, the so-called initial injection rate is increased, the injection amount of fuel injected during the ignition delay period is increased, combustion is rapidly increased, and engine noise is reduced. Various problems, such as an increase and an increase in NOx emission, occur. Some vortex-chamber engine fuel injection devices have a throttle at the tip of the nozzle needle to reduce the initial injection rate.However, when the valve is closed, the rapidity of shutting off fuel injection, that is, poor injection is worsened. appear.

Accordingly, an object of the present invention is to provide a fuel injection valve whose injection rate can be adjusted. Another object of the present invention is to provide a fuel injection system in which the initial injection rate is suppressed and the fuel injection is quickly shut off.

[0011]

According to the first aspect of the present invention, a fuel injection valve has a fuel injection hole formed at a tip thereof and a high pressure fuel is always introduced therein. And a control rod that slides in the guide hole integrally with the valve needle in the direction of displacement of the valve needle. In the valve needle, a pressure chamber formed so as to surround the valve needle constantly applies the pressure of the high-pressure fuel in the valve opening direction. A control chamber is formed with the rear end surface of the control rod as a part of the chamber wall surface, and a control oil pressure introduced through a throttle acts on the control rod in a valve closing direction of the valve needle. Then, the level of the pressure in the control chamber is switched by a valve section that switches between communication and shutoff of the control chamber and the low-pressure discharge flow path, and the valve needle is operated in the valve opening direction or the valve closing direction. In the above configuration, the valve section forms a vertical hole inside the control rod, and inserts a rod-shaped spool that slides in the vertical hole. A communication port is formed, and when the spool is displaced in the valve opening direction of the valve needle, the control chamber and the discharge flow path communicate with each other via the port. And a spring member that constantly biases the spool in the valve closing direction of the valve needle, an armature provided integrally with the spool, and a solenoid that electromagnetically drives the armature in the valve needle opening direction is provided. The lift amount of the valve needle is adjusted according to the amount of electricity.

When the spool is displaced in the valve-opening direction of the valve needle, the control chamber communicates with the discharge passage through the port to reduce the pressure in the control chamber, and the control rod moves together with the valve needle to open the pressure chamber. Due to the valve-direction acting force, the spool is displaced in the valve opening direction following the spool, and when the spool stops, the control rod and the valve needle also stop. That is, the lift amount of the valve needle is set at the spool stop position. The stop position of the spool is a position where the suction force received from the solenoid by the armature integrated with the spool and the spring force of the spring member are balanced, so that the more the amount of electricity supplied to the solenoid, the closer to the valve opening direction. That is, the lift amount of the valve needle can be adjusted in accordance with the amount of current supplied to the solenoid.

According to a second aspect of the present invention, the fuel injection system includes the fuel injection valve and an energizing means variably energizing the solenoid, and the energizing means is configured to inject the fuel. At the start, the current is gradually increased from a small amount of current and is increased to a predetermined amount of current, and at the end of injection, the current is immediately cut off from the predetermined amount of current.

At the start of fuel injection, the amount of electricity supplied to the solenoid is reduced so that the valve needle becomes an intermediate lift,
The initial injection rate can be suppressed. At the end of injection, the power supply to the solenoid is instantaneously shut off, the spool is instantaneously displaced downward, and the port is closed. The control chamber becomes high pressure, the control rod is displaced in the valve closing direction, the valve needle closes quickly, and the fuel injection is quickly shut off. What is called a sharp cut.

According to the third aspect of the present invention, the energizing means is configured to increase the energizing amount at the time of energizing in two stages, thereby easily achieving both the suppression of the initial injection rate and the sharp cut.

[0016]

FIG. 1 shows an overall longitudinal section of a fuel injection valve according to the present invention, and FIG. 2 shows an enlarged section of a main part thereof. FIG. 3 shows a fuel injection system of the present invention using the fuel injection valve of the present invention. In FIG. 3, the engine 4 is provided with a plurality of fuel injection valves 1 corresponding to the combustion chambers of each cylinder. These fuel injection valves 1 are connected to a high-pressure accumulating pipe common to all cylinders, a so-called common rail 501, so that high-pressure fuel is supplied to the fuel injection valves 1. Common rail 50
1 is connected to a variable discharge amount high pressure pump 504 via a supply pipe 502 and a discharge valve 503, and continuously accumulates fuel of a high predetermined pressure corresponding to the fuel injection pressure. The variable discharge high pressure pump 504 pressurizes the low pressure fuel sucked from the fuel tank 505 via the feed pump 506 to a high pressure, and controls the fuel in the common rail 501 to a high pressure.

The electronic control unit (ECU) 6 for controlling the fuel injection system receives detection signals from various sensors. For example, rotation speed and load information are input from the illustrated engine speed sensor 701 and load sensor 702. And EC
U6 determines the optimal injection timing and injection amount (injection period) according to the engine state determined by these signals, outputs a control signal to the fuel injector 1, and the fuel injector 1 controls the fuel injector 1 based on the control signal. The fuel is injected into the combustion chamber. Further, a detection signal of a common rail pressure is input to the ECU 6 from a pressure sensor 703 provided on the common rail 501, and the ECU 6 adjusts the variable discharge amount so that the common rail pressure becomes an optimum value set in advance according to a load and a rotation speed. The discharge amount of the high-pressure pump 504 is controlled.

1 and 2, the fuel injection valve 1 comprises a main body 2 for injecting fuel and an electromagnetic spool valve 3 for injection control.

The main body 2 has a nozzle holder 201 formed in a substantially rod shape and a distance piece 202 at the lower end thereof.
And a nozzle body 204 tightened and fixed by a nozzle retaining nut 203 through the nozzle body 204. A spacer 205 and a body 206 are provided at the upper end of the nozzle holder 201. The spacer 205 and the body 206 are housed in the solenoid cover 310 together with the components of the linear solenoid 302 constituting the electromagnetic spool valve 3, and are tightly integrated with the nozzle holder 201 by screwing the solenoid cover 310 with the nozzle holder 201. ing. Further, the nozzle holder 201 is provided with an inlet portion 207 extending obliquely upward, and is connected to the common rail 501 (FIG. 3).

A through hole 208 is formed in the nozzle holder 201 in the vertical direction. A recess 209 is formed in the spacer 205 and the body 206 so that
Is in communication with A vertical hole 210 having an upper end opening is formed in the nozzle body 204 as a cylinder 210, and a fuel injection hole 211 is formed at the tip thereof. Cylinder 21
0 communicates with the through hole 208 of the nozzle holder 201.

Nozzle holder 201, nozzle body 204
For example, an introduction channel 214 for introducing high-pressure fuel from the common rail 501 is formed, and an inlet 215 is opened at the tip of the inlet 207. The introduction flow path 214 is branched into two at the root position of the inlet 207, and the tip of the flow path 216 facing downward is open to the enlarged diameter part 213 of the cylinder 210 of the nozzle body 204. The tip of the flow path 217 that branches off and opens upward is opened in the side wall surface of the concave portion 209 of the body 206. Channel 2 going upward
A throttle 218 is provided in the middle of 17, and regulates the flow of fuel.

A bar filter 219 is provided immediately downstream of the inlet 215 of the introduction flow passage 214, and the fuel is removed therefrom.

A nozzle needle 220 serving as a valve needle for controlling fuel injection is provided in the cylinder 210. The nozzle needle 220 is a stepped rod-shaped body. The upper half 221 is in liquid-tight sliding contact with the peripheral wall surface of the cylinder 210, and the step 222 is formed at the position of the enlarged diameter portion 213 of the cylinder 210. The lower half 223 of the nozzle needle 220 having a diameter smaller than the inner diameter of the cylinder 210 has a conical valve body 224 at the tip,
Seat portion 2 formed slightly above fuel injection hole 211
12 is seated (the figure is at the time of sitting). The pressure of the high-pressure fuel filled in the enlarged diameter portion 213 of the cylinder 210 acts upward on the step portion 222 of the nozzle needle 220, and constantly urges the nozzle needle 220 upward, that is, in the valve opening direction. The diameter part 213 is an injection chamber 213 that is a pressure chamber.

In the through hole 208 of the nozzle holder 201, a rod 225 and a spring 227 are accommodated coaxially above the nozzle needle 220. Rod 22
5 has an annular projection 22 for receiving a spring 227 at the lower end thereof.
6 is formed, and the spring 227 constantly urges the nozzle needle 220 downward, that is, in the valve closing direction, via the rod 225 at all times.

In the through hole 208, a control rod 228 is provided above the rod 225. Except for a part of the rod 225, the control rod 228 is in liquid-tight sliding contact with the peripheral wall surface of the through hole 208 as a guide hole. .

The upper end surface 229 of the control rod 228 and the recess 2
The control room 230 is formed with the surface 09 as the room wall surface. High-pressure fuel is introduced into the control chamber 230 from the introduction passage 214 via the throttle 218. When the control chamber 230 is filled with the high-pressure fuel and the control chamber 230 becomes high pressure, a pressing force on the nozzle needle 220, which is a combined force of the fuel pressure of the control chamber 230 and the spring force of the spring 227, causes the injection chamber 21.
No. 3 becomes more dominant than the pushing force on the nozzle needle 220 and pushes down the nozzle needle 220. on the other hand,
The fuel in the control room 230 is discharged as described later and the control room 2
When the pressure of the nozzle 30 becomes low, the pressing force on the nozzle needle 220 is reduced by the pressure of the nozzle needle 220 of the injection chamber 213.
And pushes the nozzle needle 220 upward.

The electromagnetic spool valve 3 switches between a high pressure and a low pressure in the control chamber 230, and comprises a switching valve portion 301 and a driving linear solenoid 302.

The valve portion 301 has a control rod 228 having a vertical hole 303 opened at the upper end thereof. Control rod 228
Is formed with a flow path 305, one end of which is connected to the control rod 22.
8 is open at the upper end surface 229, and the other end is open at the peripheral wall surface of the vertical hole 303. On the peripheral wall surface of the vertical hole 303, a flow path 305 is provided.
An annular concave portion 306 is formed at the opening position of the port 306 to form a port 306. The port 306 is always in communication with the control room 230 via the flow path 305.

A through hole 307 is formed coaxially with the vertical hole 303 in the body 206 forming the upper wall of the control room 230.
A tubular spool valve 308 is inserted into the vertical hole 303 and the through hole 307, and the vertical hole 303 and the through hole 3
07 in liquid-tight sliding contact with the peripheral wall surface. Spool valve 308
The upper end faces a spring chamber 315 described later above the body 206, and communicates the bottom 304 of the vertical hole 303 and the spring chamber 315. The spring chamber 315 is provided with a pipe 309 that penetrates the upper wall of the solenoid housing 310.
And the fuel tank 505 (FIG. 3). Thus, the bottom 304 of the vertical hole 303, the spool valve 308,
The spring chamber 315 and the pipe 309 always communicate with the low-pressure fuel tank 505 to form a discharge channel.

When the lower end surface of the servo valve 308 is below the port 306, the port 306 is closed by the servo valve 308, and the control chamber 230 has the throttle 2
High-pressure fuel from the common rail 501 (FIG. 3) is charged through the pump 18 to a high pressure. As a result, the pushing force on the nozzle needle 220 becomes dominant. On the other hand, when the lower end surface of the servo valve 308 is located at the position of the port 306, the port 306 communicates with the fuel tank 505 through the bottom 304 of the vertical hole 303, and the fuel is returned from the control chamber 230 to the fuel tank 505. , The control room 230 is at a low pressure. As a result, the pushing force on the nozzle needle 220 becomes dominant. Thus, the lift amount of the nozzle needle 220 corresponds to the position of the spool valve 308.

Next, the linear solenoid 302 for driving the valve portion 301 will be described. Linear solenoid 302
A stator 311 is provided in a solenoid housing 310. The stator 311 has a substantially cylindrical second stator 31.
3 is a disk-shaped first stator 312, a third stator 314
Have a structure sandwiched from above and below, and a spring chamber 315 is formed. The spool valve 30 is provided in the spring chamber 315.
A cylindrical armature 316 integrated with the armature 8 is accommodated. A spring 317 serving as a spring member is interposed between the armature 316 and the third stator 314, and constantly biases the spool valve 308 downward through the armature 316. The spring chamber 315 is provided with a stopper 320 that restricts the downward displacement of the armature 316 from its bottom wall, that is, the first stator 312.

A bobbin 319 on which a coil 318 is wound is provided on the outer periphery of the spring chamber 315. When the coil 318 is energized to be excited, the stator 311 is turned on.
Generates a suction force on the armature 316 to drive the servo valve 308 upward.

When the coil 318 is de-energized, the servo valve 308 moves the stopper 3
The lower limit position is defined by 20 (see FIG. 2). The servo valve 308 is at the lower limit position and the nozzle needle 2
When port 20 is in the closed position, port 306 of valve section 301
Are set by the servo valve 308 so as to be closed.

At the time of energization, the servo valve 308 stops at a position where the attractive force received by the armature 316 from the stator 311 and the spring force of the spring 317 are balanced. I do. Therefore, the lift amount of the nozzle needle 220 can be adjusted according to the amount of current supplied to the coil 318.

The ECU 6 (FIG. 3) as an energizing means for controlling energization of the coil 318 will be described. FIG.
The CU 6 and its peripheral circuits are shown.

The ECU 6 includes a load sensor 702, a pressure sensor 703, an intake pressure sensor 704, an intake temperature sensor 705,
A / D converter 61 for converting an analog signal output from cooling water temperature sensor 706 to a digital signal, waveform shaping circuit 62 for shaping a pulse signal output from rotation speed sensor 701, A / D converter 61 or waveform Shaping circuit 6
CPU 63 and CPU 6 that execute the injection control of the fuel injection valve 1 and the discharge amount control of the variable discharge amount high pressure pump 504 based on the detection signals of the sensors 701 to 706 input through the CPU 2.
ROM 64 in which a control program and various data necessary for executing control processing by the CPU 3 are stored in advance.
3, a RAM 65 for temporarily reading and writing data necessary for executing the control processing, and a discharge amount control solenoid valve for controlling the discharge amount of the electromagnetic spool valve 3 of the fuel injection valve 1 and the variable discharge high pressure pump 504. 507 are constituted by drive circuits 66 and 67 which respectively output drive signals.

The drive circuit 66 for driving the electromagnetic spool valve 3 will be described with reference to FIG. One end of the coil 318 of the electromagnetic spool valve 3 is connected to the battery power supply + VB,
The other end is connected to the collector terminal of the first transistor 662 via the resistor 661 and to the collector terminal of the second transistor 664 via the resistor 663. The emitter terminals of both transistors 662 and 664 are connected to the ground potential terminal.

A drive signal A and a drive signal B are output from the CPU 63 to the drive circuit 66 as drive signals. The drive signal A and the drive signal B are binary signals of ON and OFF, and the drive signal A is supplied to the first transistor 662 via the resistor 665.
The drive signal B is input to the base terminal of the second transistor 664 via the resistor 666. Each transistor 662, 66
4 are connected to ground potential terminals via resistors 667 and 668, respectively.

A Zener diode 6 is connected between the base terminal of the second transistor 664 and the other end of the coil 318.
69 is connected using the other end of the coil 318 as a cathode.

With such a circuit configuration, when the drive signals A and B are both off, both transistors 66
2,664 is turned off, and no current flows through the coil 318. When the drive signal A is on and the drive signal B is off, the first transistor 662 is on and the coil 318
Current flows through When the drive signals A and B are both turned on,
Both transistors 662 and 664 are turned on, and coil 3
The current flowing through 18 increases by the conductance of the resistor 663 connected to the collector terminal of the second transistor 664 as compared to the case where only the drive signal A is on.

Thus, the amount of energization to the coil 318 can be set to two levels (three levels when non-energization is included) by the combination of the on / off states of the drive signals A and B. For example, + VB is 12
V, the resistance value of the resistors 661 and 663 is 10Ω, and the coil 31
Assuming that the resistance value of 8 is 2Ω, the current flowing through the coil 318 is 1 A when only the drive signal A is on, and is about 1.7 A when both the drive signals A and B are on. In the following description, description will be made using such numerical values.

The operation of the above fuel injection system will be described.
FIG. 6 is a time chart showing the operation of each unit of the device before and after the fuel injection period. FIG. 7 shows time points ta and tb in FIG.
, Tc, td, valve section 301 of solenoid spool valve 3
7A is an enlarged view of FIG. 7A, and FIG.
7 (b) shows the result at time tb, FIG. 7 (c) shows the result at time tc, and FIG. 7 (d) shows the result at time td.

At time ta before the injection period, the drive signals A,
B is off, and coil 318 is not excited. The servo valve 308 is at the lower limit position defined by the stopper 320. In this state, since the port 306 is closed, the pressure of the control chamber 230 is the same high pressure as the common rail, and the nozzle needle 220 is closed.

Thereafter, when the injection timing comes, the drive signal A is turned on. The current flowing through the coil 318 gradually increases,
1A. As the current flowing through the coil 318 increases, the armature 316 receives an attractive force from the stator 311 according to the current value of the coil 318, and the servo valve 308 rises.

At time tb, the servo valve 308 has its lower end surface raised to the lower end position of the port 306. That is, the port 306 starts opening from this point. The high-pressure fuel in the control chamber 230 is gradually returned to the fuel tank 505 via the port 306. Since the introduction of high-pressure fuel from the common rail 501 to the control room 230 is restricted by the throttle 218, the pressure in the control room 230 becomes low. Then, the lift of the nozzle needle 220 is started, and the fuel injection is started.

The control rod 228, rod 225, and nozzle needle 220 rise following the servo valve 308. When the servo valve 308 stops at the position corresponding to the 1A energization of the coil 318, the nozzle needle 220 maintains the state of the intermediate lift, and the fuel is injected into the combustion chamber from the fuel injection hole 211 at the injection rate defined by this lift position. Is done.

In the conventional system, the nozzle needle opens immediately when the fuel injection timing comes, so the injection rate becomes high from the beginning of the injection period as shown by the broken line, whereas in the system of the present invention, Since the initial injection rate can be suppressed, combustion gradually expands, good quietness of the engine,
The effect of reducing the emission of NOx and the like is obtained.

The initial injection rate is determined by the drive signal A as described above.
Depends on the current value of the coil 318 when only
Since the current value can be set to a desired value only by selecting the resistance value of the resistor 661, an initial injection rate suitable for the engine can be easily obtained.

When the drive signal B is turned on in addition to the drive signal A, the current flowing through the coil 318 doubles to about 1.7 A. As a result, the armature 316 becomes the stator 311
And the servo valve 308 further rises.

At time tc when the servo valve 308 is rising,
Again, the control chamber 230 and the fuel tank 5 via the port 306
05 communicates, the pressure in the control chamber 230 decreases, the nozzle needle 220 further lifts, and the injection rate increases. Then, when the nozzle needle 220 is completely opened, the injection is performed at the maximum fuel injection rate thereafter.

Thereafter, at a predetermined injection end timing, the drive signals A and B are simultaneously turned off, the suction force of the armature 316 from the stator 311 is released, and the spring 317 is released.
The servo valve 308 descends due to the spring force of.

At time td when the servo valve 308 is descending,
The port 306 is closed by the servo valve 308, the pressure in the control chamber 230 increases again, and the nozzle needle 220 lowers. Then, the servo valve 308 reaches the lower limit position defined by the stopper 320, the nozzle needle 220 also closes, and the injection ends. Each part of the device returns to the state before the fuel injection. As described above, when the valve is closed, the drive signals A and B are simultaneously turned off, whereby the nozzle needle 220 is instantly closed, and a sharp cut can be achieved.

As described above, in the present system, both suppression of the initial injection rate and sharp cutting can be achieved.

In the system according to the present embodiment, the current value during energization is applied to the coil in two stages, but a current value in more than two stages may be applied.
In this case, the injection control can be made so that the initial injection rate is increased in a finer stepwise manner, or selected from different initial injection rates depending on engine conditions.

[Brief description of the drawings]

FIG. 1 is an overall vertical sectional view of a fuel injection valve of the present invention.

FIG. 2 is a longitudinal sectional view of a main part of the fuel injection valve of the present invention.

FIG. 3 is a configuration diagram of a fuel injection system of the present invention using the fuel injection valve.

FIG. 4 is a configuration diagram of an electronic control unit used for controlling a fuel injection valve in the fuel injection system of the present invention.

FIG. 5 is a circuit diagram of a drive circuit of the electronic control unit for energizing a fuel injection valve.

FIG. 6 is a time chart of the fuel injection system of the present invention.

FIGS. 7 (a), (b), (c), and (d) are longitudinal cross-sectional views of main parts of the fuel injection valve of the present invention having different operation timings.

FIG. 8 is an overall vertical sectional view of one conventional fuel injection valve.

FIG. 9 is a longitudinal sectional view of a main part of one conventional fuel injection valve.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel injection valve 208 Through hole (guide hole) 210 Cylinder (valve cylinder) 211 Fuel injection hole 213 Injection chamber (pressure chamber) 220 Nozzle needle (valve needle) 228 Control rod 230 Control chamber 301 Valve section 302 Linear solenoid (solenoid) 303 Vertical hole 304 Bottom (discharge channel) 306 Port 308 Spool valve (spool, discharge channel) 309 Piping (discharge channel) 315 Spring chamber (discharge channel) 316 Armature 317 Spring (spring member) 6 Electronic control unit ( Energizing means)

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02M 51/06 F02M 51/06 Z

Claims (3)

[Claims] 1. A valve cylinder having a fuel injection hole formed at a tip thereof and constantly introducing high-pressure fuel, a valve needle provided in the valve cylinder and displaced along the valve cylinder, and a guide hole formed integrally with the valve needle. A control rod that slides in the direction of displacement of the valve needle, a pressure chamber that is formed surrounding the valve cylinder and causes high-pressure fuel to act on the valve needle in the valve opening direction, and a rear end surface of the control rod as part of the chamber wall It has a control chamber that is formed and controls the control oil introduced through the throttle to act on the control rod in the valve-closing direction of the valve needle, and a valve unit that switches between communication and shutoff between the control chamber and the low-pressure discharge passage. In the fuel injection valve, the valve needle is switched in the valve opening direction or the valve closing direction by switching the level of the pressure in the control chamber by switching the valve portion.
The valve section has a vertical hole formed inside the control rod, a rod-shaped spool sliding along the vertical hole is inserted into the vertical hole, and the peripheral wall of the vertical hole surrounds the spool and communicates with the control chamber. A port is formed, and when the spool is displaced in the valve opening direction of the valve needle, the control chamber and the discharge flow path communicate with each other through the port, and the spool is always attached to the valve needle in the valve closing direction. A biasing spring member, an armature provided integrally with the spool, and a solenoid that electromagnetically drives the armature in the valve needle opening direction, and adjusts the lift amount of the valve needle according to the amount of electricity supplied to the solenoid. A fuel injection valve characterized in that: 2. The fuel injection valve according to claim 1, further comprising: an energizing unit configured to variably energize the solenoid, wherein the energizing unit gradually reduces the amount of energization at the start of fuel injection. A fuel injection system that is set so as to increase the current to a predetermined energization amount, and to immediately cut off the energization from the predetermined energization amount at the end of fuel injection. 3. The fuel injection system according to claim 2, wherein said energizing means switches the amount of energization during energization between two stages.