JPH11107836A - Fuel injection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection device capable of easily responding to the request of a fuel increase even at the time of a high speed by shortening injection delay timing at the time of high-speed running of an internal combustion engine. SOLUTION: In a fuel injection device provided with a fuel pump 5 for supplying fuel from a fuel tank 3 to an injector 2, a driving power source circuit 8 for generating a driving voltage Vi to be applied to the exciting coil of the injector 2 and an injector trigger circuit 802 supplying a driving current supplied from the driving power source circuit 8 to the exciting coil of the injector 2 when an injection command signal is provided, the driving power source circuit 8 is composed of an AC generator 11 driven by an internal combustion engine and a rectifier 12 for rectifying the output of the AC generator 11, and the size of the driving voltage Vi is increased following an increase in an engine speed from the starting time of the internal combustion engine to the time of high speed running.

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 an internal combustion engine.

[0002]

2. Description of the Related Art FIG. 9 shows an overall structure of a fuel injection device used in an internal combustion engine. This injection device is provided with an intake pipe 1a of an internal combustion engine 1 when an injection command signal is given. An injector 2 for injecting fuel into the fuel tank (a fuel injection space), a fuel pump 5 for pumping fuel from a fuel tank 3 to a fuel supply line 4 leading to the injector 2, and a fuel supply line 4 and a fuel supply line. And a pressure regulator (pressure regulator) 6 provided between the tank 3.

The fuel pump 5 operates using a battery 7 as a power supply, and supplies fuel to the injector 2.

The injector 2 has a needle valve which is driven by an electromagnet to open and close, and a nozzle which injects fuel when the needle valve is opened. The injector 2 has a pressure applied from a fuel pump side and an engine. The pressure difference from the pressure in the intake pipe 1 is always applied as the fuel pressure.

[0005] The pressure in the intake manifold of the internal combustion engine is given to the pressure regulator 6 in addition to the pressure normally given from the fuel pump, and when the difference (fuel pressure) between the two pressures exceeds a set value, the fuel pump is turned on. A part of the fuel supplied from the fuel tank is returned to the fuel tank 3. With this pressure regulator,
The fuel pressure applied to the injector is kept substantially constant with respect to the rotation speed.

[0006] An injector driving device 8 is provided to drive the injector 2. The injector driving device includes a driving power supply circuit for generating a driving voltage applied to an exciting coil of the injector, and the driving power supply circuit when an injection command signal Vs is given from an injection command signal generating means 9 realized by a microcomputer. And an injector trigger circuit for supplying a drive current to the exciting coil of the injector 2 from the injector trigger circuit.

The injection command generating means 9 obtains rotation speed information and engine rotation angle information from a pulse signal Vp obtained from, for example, a signal generator 10 driven by an internal combustion engine, and determines an injection start position at each rotation speed. Then, an injection command signal Vs having a predetermined time width is given to the injector driving device 8 at the injection start position. While the injection command signal Vs is being supplied, the drive power supply circuit supplies the exciting coil of the injector as shown in FIG.
The driving voltage Vi shown in FIG. Since the exciting coil has inductance, the rise of the drive current Iij flowing through the exciting coil is delayed. When a predetermined delay time tb elapses after the injection command signal is given and the drive current Iij reaches a predetermined injection start level Ion, the needle valve of the injector 2 opens to spray mist fuel into the intake manifold. .

[0008] The fuel injection amount from the injector 2 is determined by the fuel pressure and the injection time. When the injection time is constant, the injection amount increases as the fuel pressure increases.

Since the supply of fuel to the engine must be performed within a predetermined section, a period during which fuel injection from the injector is effective (called an effective injection period) is performed as shown in FIG. It becomes shorter as the rotation speed N [rpm] increases. That is, it becomes necessary to inject a predetermined amount of fuel in a shorter time as the engine speed increases,
In order to secure the required fuel injection amount when the engine is running at a high speed, the fuel pressure must be set to a somewhat high level.

The amount of fuel injected from the injector can be adjusted by changing the length of time during which the injection command signal is given, but the fuel consumption (fuel consumption) required by the engine [l / H]
r] generally increases with an increase in the rotation speed and the throttle opening, and therefore, the length of time for giving the injection command signal to the injector needs to be increased with an increase in the rotation speed. It is necessary to make it longer as the throttle opening increases.

In an actual fuel injection device, a damper or the like for further reducing the pulsation of fuel may be inserted between the fuel pump 5 and the injector 2, but these are not shown in FIG. It is.

[0012]

Since the injector of the fuel injection device is driven by an electromagnet, the drive current Iij is predetermined after the drive voltage is applied as shown in FIG. 6 due to the inductance of the exciting coil. Level Ion
It is inevitable that a delay time tb will occur before the fuel injection is started.

Conventionally, the drive voltage Vi is kept constant regardless of the number of revolutions from low to high engine speeds. Therefore, fuel is applied after the drive voltage is applied as shown by a straight line a in FIG. The delay time before injection (called injection delay time) was constant regardless of the rotational speed.

However, as shown in FIG. 8, the effective injection period is shortened with an increase in the rotational speed, and as described above, if the injection delay time is constant regardless of the rotational speed, The ratio of the injection delay time to the injection effective period increases as the engine speed increases, and the higher the engine speed, the more difficult it becomes to meet the demand for increasing the fuel. there were.

It is an object of the present invention to provide a fuel injection device in which the injection delay time of the engine at high speed is shortened so that it is possible to easily meet the demand for increasing the amount of fuel even at high speed.

[0016]

SUMMARY OF THE INVENTION The present invention is directed to an injector having an exciting coil for injecting fuel into a fuel injection space of an internal combustion engine when a drive current of a predetermined level or more is applied to the exciting coil. A fuel pump for supplying fuel from the tank to the injector, a drive power supply circuit for generating a drive voltage applied to the excitation coil, and an injector for supplying a drive current from the drive power supply circuit to the excitation coil of the injector when an injection command signal is given The present invention relates to a fuel injection device having a trigger circuit.

In the present invention, the driving power supply circuit includes:
The circuit has a characteristic of increasing the magnitude of the drive voltage as the engine speed increases from the start of the internal combustion engine to the time of high speed.

It is preferable that the drive power supply circuit is constituted by a circuit including an AC generator driven by an internal combustion engine and a rectifier for rectifying the output of the AC generator.

The drive voltage applied to the exciting coil of the injector does not necessarily need to be increased with the increase in the rotational speed in the entire rotational speed range of the engine. Accordingly, the driving voltage may be increased.

It is not always necessary to continuously increase the drive voltage with an increase in the number of revolutions. Instead, several set number of revolutions are determined, and the drive voltage is changed stepwise at each set number of revolutions. You may do it.

As described above, when the magnitude of the drive voltage applied to the exciting coil of the injector is increased from the start of the internal combustion engine to the high speed with the increase in the rotational speed, the exciting coil of the injector is The drive voltage applied to the motor increases as the engine speed increases, as indicated by reference numerals a, b, and c in FIG. In general, the rise of the current flowing when a voltage is applied to a coil increases as the applied voltage increases, and as described above,
If the drive power supply circuit is configured to increase the drive voltage as the engine speed increases, curves A, B, and
As shown in C, the rise of the drive current flowing through the exciting coil of the injector becomes faster as the rotational speed increases.
The delay time from when the drive voltage is applied to the exciting coil to when the drive current reaches the injection start level Ion is t3,
Like t2 and t1, it becomes shorter with an increase in the rotational speed.

Therefore, with the above configuration, the injection delay time is shortened with an increase in the engine speed, so that the ratio of the injection delay time to the effective injection period at the time of high engine speed is prevented from increasing. Therefore, even when the engine is running at high speed, it is possible to easily respond to the demand for increasing the fuel.

Further, when the drive power supply circuit is constituted by an AC generator driven by an internal combustion engine and a rectifier for rectifying the output of the AC generator, a simple configuration can be achieved without providing a special control circuit. Thus, it is possible to obtain a fuel injection device that can respond to a demand for increasing the amount of fuel when the engine is running at high speed.

[0024]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 schematically shows an example of the configuration of a fuel injection device according to the present invention. In FIG. 1, reference numeral 1 denotes an internal combustion engine, 2 denotes an injector, 3 denotes a fuel tank, 5 denotes a fuel pump, and 6 denotes a pressure. Adjusters, which are the same as the conventional ones shown in FIG.

The injector driving device 8 includes a driving power supply circuit 801 for generating a driving voltage to be applied to the exciting coil, and a driving power supply circuit 801 for receiving the injection command signal Vs.
And an injector trigger circuit 802 for supplying a drive current to the exciting coil of the injector 2 from the controller. In this example, the drive power supply circuit 801 includes a circuit including a magnet type AC generator 11 attached to an output shaft of the internal combustion engine 1 and a full-wave rectifier 12 for rectifying the output of the AC generator 11. The magnitude of the drive voltage applied to the exciting coil of the injector 2 increases from the start of the internal combustion engine to the high speed as the engine speed increases.

Although not shown, a voltage regulator is connected to the output side of the rectifier of the driving power supply circuit 801 in order to prevent the voltage applied to the exciting coil of the injector 2 from becoming excessive when the internal combustion engine is running at high speed. And the voltage regulator
The drive voltage is prevented from exceeding the set value. This voltage regulator detects, for example, the voltage across the exciting coil of the injector 2 and short-circuits the output of the rectifier when the detected voltage exceeds a set value, or the output of the rectifier is applied to the injector. (Switch circuit).

The injector trigger circuit 802 is composed of a switch that maintains a conductive state while the injection command signal Vs is supplied, and the DC output voltage of the drive power supply circuit 801 is applied to the exciting coil of the injector 2 while the switch is in the conductive state. Is applied.

The magnet type alternator 11 includes a flywheel magnet rotor 11a attached to the output shaft of the internal combustion engine,
An AC voltage induced in an armature winding of the stator 11b is applied to an input terminal of the rectifier 12 of the drive power supply circuit 801.

An inductor magnetic pole portion for generating a signal is provided on the outer periphery of a flywheel constituting a yoke of the rotor 11a of the AC generator, and a signal generating member 11c is opposed to the magnetic pole portion. A signal generator is constituted by the magnetic pole portion on the outer periphery of the flywheel and the signal generator 11c. Each time the magnetic pole portion on the outer periphery of the flywheel faces the signal generator 11c at a predetermined rotation angle position of the engine, the signal generator 11c is generated. Generates a pulse signal Vp.

The injection command generating means 9 obtains rotation speed information and rotation angle information of the engine from the pulse signal Vp, calculates an injection start position at each rotation speed, and gives a predetermined value to the injector trigger circuit 802 at the injection start position. Is given.

FIG. 3 shows an example of the injector 2. In the figure, reference numeral 201 denotes an injector main body. One end of the main body includes a valve body 204 having a valve seat 203 around an injection port 202, and a needle 205 provided in the valve body to open and close the injection port 202. Is mounted. Body 20
1, an excitation coil 207, an iron core 208, and an iron core 208
210 composed of an amateur 209 attracted to the body
Are arranged, and the amateur 209 is connected to the needle 205. A return spring 211 is also provided in the main body 201, and the needle 205 is constantly urged by the return spring 211 so as to close the injection port 202. A fuel inlet 212 is provided at the other end of the main body 201, and a filter 213 is attached to the inlet. A connector 214 is also attached to the main body 201, and power is supplied to the coil 207 from a terminal 215 of the connector.

The injector 2 is attached to, for example, an intake pipe of an engine, and the injection port 202 is directed into the intake pipe (fuel injection space). An inlet 212 of the injector 2 is connected to a discharge port of a fuel pump 5 via a pipe 4, and fuel is supplied to the inlet 212 at a predetermined pressure (fuel pressure). Also, a cable (not shown) is connected to the connector 214,
It is connected to the injector driving device 8 via the cable.

From the injector driving device 8 to the driving coil 2
When the drive voltage Vi is applied to 07, the core 208 is excited, so that the armature 209 is attracted to the core, the needle 205 moves to the electromagnet side, and the needle valve opens. As a result, the fuel is atomized from the injection port 202 and injected into the intake pipe. When the injection command signal disappears, the coil 207 is demagnetized, and the needle 205 returns to the position where the injection port 202 is closed by the urging force of the return spring 211.

In the example shown in FIG. 1, when an injection command signal is given from the injection command generating means 9, the switch of the injector trigger circuit 802 is turned on and the drive power supply circuit 80 is turned on.
1 is applied to the exciting coil of the injector as a drive voltage. As a result, the drive current Iij flows through the exciting coil of the injector, and when the drive current reaches a predetermined injection start level Ion, the needle valve of the injector is opened and fuel injection is started. When the injection command signal disappears, the switch of the injector trigger circuit 802 is turned off, so that the driving current of the injector becomes zero, the needle valve closes, and the fuel injection stops.

As described above, when the driving power supply circuit 801 of the injector driving device 8 is constituted by a circuit including an AC generator driven by an internal combustion engine and a rectifier for rectifying the output of the generator, The drive voltage Vi increases as the engine speed N increases from the start of the internal combustion engine to the high speed. Further, when the voltage regulator is provided as described above, the drive voltage Vi applied to the exciting coil of the injector is limited to a set value or less so as not to become excessive at the time of high speed of the engine. A characteristic of a change in the driving voltage Vi with respect to the rotation speed N is, for example, as shown by a curve a in FIG.

When the driving voltage of the injector is increased as the rotational speed increases, the injection delay time of the injector can be shortened as the rotational speed increases.

For example, when the engine speed N is 2,000 rpm, 4,000 r
Assuming that the driving voltages Vi at pm and 6,000 rpm are as indicated by reference numerals a, b, and c in FIG. 5, respectively, the driving current Iij flowing through the exciting coil of the injector at these rotation speeds is as shown in FIG. Curves A, B and C are obtained, and the drive current Iij after the injection command signal is given
Reaches the injection start level Ion, and the delay time until the actual injection is started becomes shorter as the rotational speed increases, as shown by t3 → t2 → t1. Therefore, the characteristic of the injection delay time with respect to the rotation speed N is as shown by a curve b in FIG.

As described above, if the drive voltage of the injector is increased with an increase in the number of revolutions, the injection delay time is shortened with an increase in the number of revolutions. Since the ratio of the injection delay time occupying can be prevented from increasing, it is possible to easily respond to the request for increasing the amount of fuel even when the engine is running at high speed.

In the above example, a generator driven by the internal combustion engine is used as the power supply of the drive power supply circuit. However, in the present invention, the drive voltage of the injector may be increased as the rotational speed increases. The method of increasing the drive voltage is arbitrary.

For example, as shown in FIG. 2, an input of a rotational speed detection signal Vn proportional to the rotational speed N of the internal combustion engine, an input of a constant DC voltage E, and start of the engine as shown by a straight line b in FIG. Drive power supply circuit 8 that outputs drive voltage Vi that increases linearly with increase in rotation speed N from time to high speed
01 can also be used.

For example, as shown in FIG. 2, the injector trigger circuit 802 includes a resistor R1 and a collector-emitter circuit connected to the exciting coil 20 of the injector through the resistor R1.
7 with an NPN transistor Tr1 connected in series. In this example, the emitter of the transistor Tr1 is grounded, and the drive voltage Vi output from the drive power supply circuit 801 is applied to both ends of a series circuit of the exciting coil 207, the resistor R1, and the collector-emitter circuit of the transistor Tr1, and the transistor Tr1 Is given an injection command signal Vs.

In the above example, the fuel pump 5 may be driven by a battery, but the fuel pump may be driven by the output of the generator 11 driven by the internal combustion engine. When the fuel pump 5 is driven by the generator 11, the driving voltage of the fuel pump increases with an increase in the engine speed, and the discharge pressure of the fuel pump 5 increases. Therefore, the fuel pressure applied to the inlet of the injector 2 is reduced by the engine pressure. Can be increased with an increase in the number of rotations. When the fuel pressure is changed in accordance with the rotation speed in this manner, a path for returning fuel to the fuel tank 3 through the pressure regulator 6 can be omitted.

Since the fuel injection amount per unit time from the injector increases with an increase in the fuel pressure, if the fuel pressure is increased in accordance with the increase in the engine speed as described above, the engine speed is increased. In this case, the injection amount per unit time can be increased, and even at a high speed in which the injection effective period is shortened, it is possible to easily respond to the fuel increase request.

In addition, since the injection amount per unit time is reduced when the engine is running at a low speed, it is possible to prevent excessive fuel from being supplied when the engine is running at a low speed.

[0046]

As described above, according to the present invention, the drive voltage of the injector is increased from the start of the internal combustion engine to the high speed as the engine speed increases. To prevent the ratio of injection delay time to the effective injection period from increasing when the engine is running at high speed, and to easily meet the demand for increased fuel even at high engine speeds. There are advantages that can be.

In particular, according to the second aspect of the present invention, it is possible to prevent the drive voltage from exceeding the set value at the time of high speed of the engine, so that an excessive voltage is not applied to the injector at high speed. it can.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration example of a fuel injection device according to the present invention.

FIG. 2 is a block diagram showing a main part of another configuration example of the fuel injection device according to the present invention.

FIG. 3 is a cross-sectional view showing an example of the structure of an injector that can be used in the present invention.

FIG. 4 is a diagram showing an example of a relationship between a driving voltage of an injector and a rotation speed of an engine in the fuel injection device according to the present invention.

FIG. 5 is a waveform diagram showing a relationship between a drive voltage and a drive current of an injector in the fuel injection device according to the present invention.

FIG. 6 is a waveform diagram showing a relationship between a driving voltage and a driving current of an injector in a conventional injection device.

FIG. 7 is a diagram showing a relationship between an injection delay time and a rotation speed.

FIG. 8 is a diagram showing an example of a relationship between a fuel injection effective engine of an engine and a rotation speed.

FIG. 9 is a block diagram showing a configuration of a conventional fuel injection device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 2 ... Injector, 3 ... Fuel tank, 5
... Fuel pump, 8 ... Injector drive, 801 ... Drive power supply circuit, 802 ... Injector trigger circuit, 11 ...
Magnet type alternator.

Continuing from the front page (72) Inventor Yoshinobu Arakawa 3744 Ooka, Numazu-shi, Shizuoka Prefecture Inside the domestic electric company (72) Inventor Ryuji Satsukawa 3744 Ooka, Numazu-shi, Shizuoka prefecture Inside the domestic electric company (72) Inventor Endo Tsuneaki 3744 Ooka, Numazu-shi, Shizuoka Pref.

Claims (2)

[Claims] An injector for injecting fuel into a fuel injection space of an internal combustion engine when a drive current of a predetermined level or more is applied to the excitation coil; and supplying fuel to the injector from a fuel tank. A fuel pump, a drive power supply circuit that generates a drive voltage to be applied to the excitation coil, and an injector trigger circuit that flows the drive current from the drive power supply circuit to the excitation coil of the injector when an injection command signal is given. Wherein the drive power supply circuit comprises a circuit having a characteristic of increasing the magnitude of the drive voltage with an increase in engine speed from the start of the internal combustion engine to a high speed. A fuel injection device. An injector for injecting fuel into a fuel injection space of the internal combustion engine when a drive current of a predetermined level or more is applied to the excitation coil, and supplying fuel from the fuel tank to the injector. A fuel pump, a drive power supply circuit that generates a drive voltage to be applied to the excitation coil, and an injector trigger circuit that flows the drive current from the drive power supply circuit to the excitation coil of the injector when an injection command signal is given. Wherein the drive power supply circuit comprises an AC generator driven by the internal combustion engine, and a circuit including a rectifier for rectifying the output of the AC generator. That the drive voltage has a characteristic of increasing the magnitude of the drive voltage with an increase in the rotation speed of the internal combustion engine from a start to a high speed. Fuel injection apparatus according to symptoms.