JPH1077925A - Fuel injection device and its method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain rapid valve opening responsiveness by making a current flow to an inductor prior to injector valve opening, previously accumulating electromagnetic energy in an injector magnetic circuit, and forming a series circuit of the inductor and an injector magnetic coil at the time of injector valve opening so as to make the same current flow by a switching element. SOLUTION: Prior to fuel injection, a transistor switch 600 is switched on by an inductor current control signal, and a current flows to an inductor 200. At this time, a switch 610 is still in an off state, so that a current is not flowing to an injector electromagnetic coil 300. The instant a fuel injection control signal instructs injection, the switch 600 is switched off, and the switch 610 rapidly changes into an on state. At this time, an inductor current is suddenly lowered the instant the switch 600 is switched off, and then shifted at a time constant determined by a series circuit of the inductor 200 and injector electromagnetic coil 300, and the inductor current continuously flows through the injector electromagnetic circuit 300.

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 In a fuel injection device for an internal combustion engine, it is necessary to control the opening and closing of a fuel injector (injector) at high speed in order to improve the measurement accuracy of the fuel injection amount and the control response. Conventionally, an electromagnetic valve that opens and closes using electromagnetic force has been used as a fuel injection valve. However, when the electromagnetic valve is driven, the inductance of the electromagnetic coil becomes an obstacle, and it has been difficult to obtain high-speed valve opening and closing responses. For this reason, D
A method has been devised in which the battery voltage is boosted by using a C-DC converter and the valve opening response of the injector is improved by applying a high voltage (Japanese Patent Application Laid-Open Nos. 59-85434 and 5-14130). No.).

[0003]

However, in a fuel injection device using a booster circuit, inductors, capacitors, switching elements, and the like are required as circuit elements necessary for boosting, and these can withstand high voltages. There must be. In addition, a switching element having high voltage resistance is required for the drive control circuit of the injector. Therefore, there is a problem that the fuel injection device is large and expensive.
Another problem is that the voltage, and thus the injector drive current, fluctuates due to fluctuations in the battery voltage, temperature, etc., and the injector characteristics change. In addition, since a high voltage is used, there is a risk of electric shock to the human body during manufacturing, inspection, inspection, and maintenance.

An object of the present invention is to provide a fuel having both a simple structure, stable operation with respect to fluctuations in temperature and the like, and high-speed valve opening and valve closing characteristics without using a high voltage obtained by boosting a battery voltage. An object of the present invention is to provide an injection device.

[0005]

SUMMARY OF THE INVENTION The present invention provides an injector for opening and closing a valve using electromagnetic force for fuel injection, an inductor connected in series to an electromagnetic coil forming an electromagnetic valve,
The present invention relates to a fuel injection device including a switching element for opening and closing a current circuit and a control circuit for instructing the operation of the switching element.

A current flows through the inductor before the injector is opened, and electromagnetic energy is previously stored in the magnetic circuit of the inductor. When the injector is opened, the inductor and the injector electromagnetic coil form a series circuit, and the switching element operates so that the same current flows. Therefore, the electromagnetic energy stored in the inductor is instantaneously supplied to the injector electromagnetic coil as a current. Therefore, a large current can be instantaneously passed through the injector electromagnetic coil. That is, since an electromagnetic force for opening the injector electromagnetic valve is instantaneously generated, high-speed valve opening response can be obtained.

Next, after the valve is opened, it is necessary to supply a current to the injector electromagnetic coil for a predetermined period to maintain the valve open state. In the present invention, the magnitude of the holding current flowing through the electromagnetic coil after the injector valve is opened or
N / OFF is switched in a short time. At this time, by adjusting the magnitude of the holding current or the time ratio of ON / OFF, the holding current can be controlled to a predetermined value on average, so that a stable injector operation can be obtained even if there is a fluctuation in battery voltage or temperature. .

Further, when the injector is closed, the switching element operates so that the current flowing through the injector electromagnetic coil and the current flowing through the inductor flow through separate circuits, and the power supply voltage is not applied to the injector electromagnetic coil. Therefore, the electromagnetic energy stored in the electromagnetic coil magnetic circuit is emitted as an injector current. At this time, the switching element operates such that a predetermined resistance is connected in series with the injector electromagnetic coil. Alternatively, the switching element itself acts as a high resistance. As a result, the conversion of electromagnetic energy to heat energy is promoted, and the electromagnetic force is quickly eliminated, so that the injector closes at a high speed.

[0009]

FIG. 1 shows a first embodiment of the present invention. FIG. 1 shows an electronic control unit of an engine and a fuel injection device drive unit for one cylinder. In this embodiment, the battery 10
0 and inductor 200 and injector electromagnetic coil 3
00 is connected in series. The inductor 200 and the electromagnetic coil 300 include resistors 210 and 310 and inductances 220 and 320, respectively. The inductor current control signal generated by the engine electronic control device 400 is supplied to the transistor switch 600 (SW1), and the fuel injection control signal is supplied to the transistor switch 610 (SW2). The transistor switch 60 is controlled by each signal.
ON / OFF of 0,610 is controlled.

The engine electronic control unit 400 includes a microcomputer 401, a signal input circuit 402, a ROM 403, and an RA.
M404 and a control signal output circuit 405 are incorporated. The microcomputer 401 receives a flow rate of the engine intake air, a crank angle sensor 501, a battery voltage sensor 502, and a temperature sensor 503 through a signal input circuit.
Input signal. The microcomputer 40
1 determines the control output of the control signal output circuit 405 using these sensor input signals and the data stored in the ROM 403 and the RAM 404.

The operation timing and current behavior of the engine electronic control unit and the fuel injection device drive unit of FIG. 1 will be described with reference to the timing chart of FIG. First, inductor 2
The behavior of the current flowing through 00 is as follows. First, prior to the start of fuel injection, an inductor current control signal is output. As a result, the transistor switch 600 turns on,
A current flows through the inductor 200. At this time, the transistor switch 610 is still in the OFF state, and no current flows through the injector electromagnetic coil 300. At the moment when the fuel injection control signal instructs the injection, the switch 600
Is rapidly changed to OFF, and the switch 610 is rapidly changed to ON.
At this time, since the electromagnetic energy stored in the inductor magnetic circuit does not disappear immediately, the inductor current continues to flow through the electromagnetic coil 300. That is, switch 6
At the moment when 00 is turned off, the inductor current rapidly changes from the point A to the point B in FIG.
To point C of FIG. Thereafter, when the fuel injection is stopped, the switch 610 is turned off, and the inductor current becomes zero.

In the above description, the start timing and the conduction time of the inductor current control signal are determined by the crank angle sensor 501, the battery voltage sensor 502, and the temperature sensor 50.
The microcomputer 401 decides with reference to the signal of No. 3. For example, when the battery voltage is low, the energization time is lengthened so that a predetermined current is controlled to flow through the inductor 200. The value of the resistor 210 changes with temperature.
In order to compensate for this, for example, the temperature of the cooling water is measured by the temperature sensor 503, and the energization time is set to a predetermined value corresponding to this temperature.

On the other hand, the behavior of the current flowing through the injector electromagnetic coil 300 is as follows. When the fuel injection is stopped, the switch 610 is OFF, so that the electromagnetic coil 3
No current flows through 00. At the moment when the fuel injection control signal instructs the injection, the switch 600 is turned off and the switch 610 is turned off.
Is turned ON, all the current flowing through the inductor 200 passes through the electromagnetic coil 300. Therefore, as shown in FIG.
, A current starts to flow rapidly from zero to point E. The current value at the point E is the inductor current value A immediately before the start of fuel injection, and the value L of the inductance 220 of the inductor 200.
1 and the value L2 of the inductance 220 of the electromagnetic coil 300 is determined in principle, and has the following relationship: B = E = A {L1 / (L1 + L2)} (1) However, actually, the inductor 200 and the electromagnetic coil 300 generate a large back electromotive force when the current is switched. Therefore, it is necessary to protect the transistor switch 600 from the back electromotive force. In FIG. 1, a Zener diode 700 is provided to protect the switch 600, and has a clamp function of limiting a voltage to a predetermined value or less. As a result, a voltage higher than the clamp voltage of the Zener diode 700 is not applied to the electromagnetic coil 300. For this reason, the current value at the point E becomes somewhat smaller than the above equation (1) according to the value of the clamp voltage. The time required for the current of the electromagnetic coil 300 to go from zero to point E also depends on the clamp voltage. Therefore, by selecting the clamp voltage of the Zener diode 700 to a predetermined value, the time or gradient of the initial current increase of the electromagnetic coil can be adjusted.

Since the current flowing through the electromagnetic coil 300 after reaching the point E is equal to the current flowing through the inductor 200, the curve of BC and the curve of EF in FIG. 2 completely match.
At the moment when the injection is stopped, the switch 610 is turned off, so that the resistor 800 is connected in series to the electromagnetic coil 300. At the moment when the injection is stopped, the electromagnetic energy stored in the magnetic circuit of the electromagnetic coil is transferred to the electromagnetic coil 300 and the resistor 80.
It is emitted as a current flowing through a series circuit of zeros. At this time, if the resistance 800 is increased to some extent, the electromagnetic energy is rapidly converted into heat mainly in the resistance 800. Therefore, as shown by EG in FIG. 2, the injector electromagnetic coil current becomes zero in a short time.

As described above, according to the first embodiment, a large current can be instantaneously supplied to the injector electromagnetic coil, and this current can be quickly removed. Therefore, the generation and disappearance of the electromagnetic force for driving the solenoid valve also occurs rapidly, so that the valve opening and closing operations of the injector can be controlled at high speed. In the present embodiment shown in FIG. 1, the Zener diode 700 for voltage clamping is
It was placed between the collector and the emitter of 00. However, the same effect can be obtained even if it is installed between the collector and the base of the transistor switch 600. In this embodiment,
At the time of stopping the fuel injection, control was performed so that the electromagnetic energy stored in the electromagnetic coil 300 was consumed by the resistor 800. However, the resistor 800 is removed and the transistor switch 61 is turned off when the transistor switch 610 is turned off.
Even if electromagnetic energy is applied to the zero resistance, the same effect can be obtained.

FIG. 3 shows a second embodiment of the present invention.
In the second embodiment, in addition to the first embodiment, stabilization control of a current flowing through the injector electromagnetic coil 300 is performed. The injector electromagnetic coil current is detected as a voltage across the resistor 810, and is input to the operational amplifier 910 via the averaging circuit 900. This value is compared with the target voltage value which is also input to the operational amplifier 910, and the difference voltage is supplied to the PWM control circuit 410. The PWM control circuit 410 generates a rectangular pulse having a predetermined frequency. PWM
The control circuit 410 changes the pulse width of the generated rectangular pulse, that is, the duty ratio, according to the sign of the difference signal output of the operational amplifier 910 and the magnitude of the difference signal output. That is, if the average value of the voltage between both ends of the resistor 810 is smaller than the target voltage value and the output signal of the operational amplifier 910 is positive, the PWM control circuit 410 widens the generated rectangular pulse width and increases the duty ratio. Conversely, if the average value of the voltage across the resistor 810 is greater than the target voltage value and the output signal of the operational amplifier 910 is negative, the PWM control circuit 410 reduces the generated rectangular pulse width and decreases the duty ratio. Operate.

The output rectangular pulse of the PWM control circuit 410 is connected to an AND gate 420. As a result, FIG.
As shown in the figure, the switch 610 is turned ON / OFF by the PWM signal during the fuel injection period. This ON /
As described above, the OFF duty ratio is determined by the resistance 8
When the average value of the voltage across the terminals 10, that is, the average value of the injector electromagnetic coil current is large, the value becomes small, and conversely, when the average value of the injector electromagnetic coil current is small, the value becomes large. Therefore, during the injection period, the injector electromagnetic coil current changes according to the PWM signal as shown in FIG. 4, and is controlled so that its average value becomes equal to the target voltage value.

The microcomputer 401 generates a PWM circuit control signal through a control signal output circuit 405,
It is supplied to the PWM control circuit 410. PWM control circuit 41
0 outputs a rectangular pulse only during the period when the PWM circuit control signal is input, and executes the PWM control operation. After starting the fuel injection, the microcomputer 401 is delayed by a time determined with reference to sensor signals such as a battery voltage and a temperature,
Generate a PWM control signal. This makes it possible to adjust the start timing of the injector current PWM control operation in response to a change in the injector resistance 310 due to, for example, temperature.

As described above, according to the second embodiment, since the average value of the driving current of the injector electromagnetic coil is controlled to be always a predetermined value, the resistance value change due to the fluctuation of the battery voltage and the temperature change. However, the injector solenoid valve can be controlled stably.

FIG. 5 shows a third embodiment of the present invention.
The third embodiment differs from the first embodiment in that one transistor switch is provided. In the present embodiment, the engine electronic control unit 400 generates a fuel injection control signal and controls ON / OFF of the transistor switch 600. Switch 60
When 0 is turned off, current starts to flow to the electromagnetic coil 300 instantaneously, and when the switch 600 is turned on, the electromagnetic coil current disappears. The inductor 200 is energized when fuel injection is stopped. The switch 90 is linked with the key switch, and is turned on while the engine is rotating. According to the third embodiment, while reducing the number of transistor switches,
As in the first embodiment, the injector solenoid valve can be controlled at high speed.

FIG. 6 shows a fourth embodiment of the present invention.
One injector 200 is used to control two injectors. That is, the first injector electromagnetic coil 300, the resistance 311 and the inductance 32
1 is instantaneously passed by the inductor 200 to the second injector electromagnetic coil 301 consisting of A first fuel injection signal to the first injector generated by the engine electronic control unit 400 is supplied to the switch 610, and the current of the electromagnetic coil 300 is controlled in accordance with the operation of the switch 600, so that the fuel injection of the first injector is performed. Is exactly the same as in the first embodiment. After the fuel injection of the first injector, the engine electronic control device 400 turns on the switch 600 by the inductor current control signal to re-energize the inductor 200. Thereafter, a second fuel injection signal is generated to the second injector, and the switch 61
1 is ON / OFF controlled, a current flows through a series circuit including the inductor 200 and the electromagnetic coil 301 for the fuel injection period, and the fuel injection operation of the second injector is completed. The operation of the second injector described above is exactly the same as the operation of the first injector except that the time is shifted.

As described above, according to the fourth embodiment, it is possible to control the injectors of a plurality of cylinders with a high-speed response using one inductor. Fourth embodiment is 4
It goes without saying that it can be expanded to a cylinder or even a multi-cylinder engine.

In the first to fourth embodiments, a transistor is used as a switching element. However, the present invention can be implemented using any switching element such as a bipolar type, a MOS type, or a relay switch. Can be.

In this embodiment, since high-speed valve opening is possible, it is preferable to use the fuel injection valve for injecting fuel directly into the cylinder of the engine. In particular, the fuel control accuracy under operating conditions that require a small amount of fuel supply is improved.

[0025]

As described above, according to the present invention, the solenoid valve of the injector can be opened and closed at a very high speed without generating a high voltage by the booster circuit, and also stably with respect to fluctuations in voltage, temperature and the like. A working fuel injection device is obtained.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of the present invention.

FIG. 2 is an operation explanatory diagram of the first embodiment.

FIG. 3 shows a second embodiment of the present invention.

FIG. 4 is an operation explanatory diagram of the second embodiment.

FIG. 5 shows a third embodiment of the present invention.

FIG. 6 shows a fourth embodiment of the present invention.

[Explanation of symbols]

100: battery, 200: inductor, 220: inductance, 300, 301: injector electromagnetic coil, 400: engine electronic control unit, 401: microcomputer, 402: signal input circuit, 403: RO
M, 404 RAM, 405 control signal output circuit 41
0: PWM control circuit, 420: AND gate, 500:
Air flow sensor, 501 ... Crank angle sensor, 502 ...
Battery voltage sensor, 503 temperature sensor, 600, 6
10, 611: transistor switch, 700: zener diode, 800, 801: resistor, 900: averaging circuit, 910: operational amplifier.

Claims (10)

[Claims] 1. A fuel injection device using an injector that opens and closes a valve by using an electromagnetic force generated by an electromagnetic coil.
An inductor and a switching circuit having one or more switching elements are installed, and the switching circuit is configured and controlled so that a driving current flows in advance before the fuel injection is started in the inductor. The fuel injection device according to claim 1, wherein the switching circuit is configured and controlled such that the drive current flowing through the inductor flows into the electromagnetic coil. 2. An injector for opening and closing a valve using an electromagnetic force generated by an electromagnetic coil, a first switching circuit for opening and closing a current circuit of the electromagnetic coil, and a control for controlling an operation of the first switching element. In a fuel injection device provided with a circuit, an inductor connected in series to the electromagnetic coil and a second switching circuit for opening and closing a current circuit of the inductor are provided, and the fuel is controlled by controlling the second switching circuit. Prior to the start of injection, a current is passed through the inductor in advance, and the first switching circuit is controlled at a fuel injection start timing, so that a current flows through a series circuit of the electromagnetic coil and the inductor. Fuel injector. 3. A fuel injection device having an injector that opens and closes a valve using an electromagnetic force generated by an electromagnetic coil.
A fuel injection device, comprising an inductor and a switching circuit, wherein a current flowing through the inductor flows through the electromagnetic coil by opening and closing the switching circuit. 4. A fuel injection device comprising an injector for opening and closing a valve using an electromagnetic force generated by an electromagnetic coil and a switching circuit for opening and closing a current circuit of the electromagnetic coil, wherein the electromagnetic coil is provided only during fuel injection. A fuel injection device comprising an inductor whose connection is controlled so that the same current flows as in (1). 5. A fuel injection system comprising: an injector for opening and closing a valve by using an electromagnetic force generated by an electromagnetic coil; and a switching circuit for opening and closing a current circuit of the electromagnetic coil. A fuel injection device comprising an inductor that generates a back electromotive force in a direction to cancel the back electromotive force generated by the fuel injection device. 6. A fuel injection system comprising: an injector that opens and closes a valve using an electromagnetic force generated by an electromagnetic coil; and a power supply that supplies a current to the electromagnetic coil, without increasing a voltage of the power supply. A fuel injection device comprising: a mechanism for flowing a current to the electromagnetic coil at a rising speed exceeding a time constant determined by a resistance component and an inductance component of the electromagnetic coil. 7. The fuel injection system according to claim 1, wherein prior to the start of fuel injection, the duration of energization of a drive current previously passed through said inductor is controlled by referring to signals from a crank angle sensor, a battery voltage sensor and a temperature sensor. A fuel injection device. 8. The fuel injection device according to claim 1, wherein a clamp element for limiting a voltage is provided at one end of the electromagnetic coil, and a clamp voltage of the clamp element is adjusted.
A fuel injection device for controlling a rise time of a current flowing through the electromagnetic coil. 9. An inductor which is connected to an on-vehicle power supply and is energized for a predetermined period prior to driving the fuel injection valve, and when the fuel injection valve is driven, energy stored in the inductor flows to the coil of the fuel injection valve. And a drive circuit for a fuel injection valve that discharges as a current. 10. An apparatus having an inductor serially connected to a vehicle-mounted power supply and an electromagnetic coil type fuel injection valve, wherein the flow to the inductor is interrupted at a fuel injection start timing, and the inductor is generated at that time. A fuel injection method, wherein energy by a back electromotive force is supplied to an electromagnetic coil of the fuel injection valve.