JPH04232361A - Injector drive for internal combustion engine and drive device - Google Patents

Abstract

PURPOSE:To actuate an injector even when a cicrocomputer to control the injector does not normally work. CONSTITUTION:A signal generator 3 is installed on an internal combustion engine, and a preliminary injection command signal Vi' is obtained from an output signal of this signal generator 3. When a microcomputer 2 normally works, an injector 6 is actuated by a main injection command signal Vi obtained from the microcomputer 2, and when the microcomputer 2 does not normally work, the injector 6 is actuated by the preliminary injection command signal Vi'.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving method and a driving device for driving an injector that supplies fuel to an internal combustion engine.

0002

2. Description of the Related Art In order to operate an internal combustion engine in an optimal state, it is important to accurately control the air-fuel ratio according to the temperature, rotational speed, etc. of each part of the engine. When fuel is supplied to an engine by an injector, the amount of fuel to be injected is determined by the time during which the injector injects the fuel (fuel injection time) and the pressure of the fuel applied to the injector. Additionally, the air-fuel ratio is affected by temperature and atmospheric pressure, so in order to properly control the air-fuel ratio, it is necessary to accurately control the fuel injection time according to control conditions such as atmospheric pressure and temperature of each part. It is.

[0003] Therefore, using a microcomputer,
Atmospheric pressure, ambient temperature, temperature of each part of the engine, engine speed,
BACKGROUND OF THE INVENTION Fuel injection devices are used that control the supply of drive current to an injector in accordance with throttle opening and the like to control fuel injection time.

FIG. 11 shows the configuration of a conventionally used fuel injection device of this type.
A microcomputer 2 that is driven by a battery power supply 1, a signal generator 3 that is attached to an internal combustion engine and generates a signal at a predetermined rotation angle position of the engine, and a signal generator 3 that converts the signal obtained from the signal generator 3 into a predetermined waveform. Waveform shaping circuit 4 that shapes the waveform into a rectangular wave (for example, a rectangular wave) and supplies it to the microcomputer.
and various sensors that provide information such as atmospheric pressure, ambient temperature, temperature of each part of the engine, throttle opening, etc. to the microcomputer, and a drive coil 6a of the injector 6 in response to an injection command signal given from the microcomputer 2. The injector drive circuit 7 provides an electric current. The injector includes a nozzle that injects fuel, a needle valve that opens and closes the nozzle, and an electromagnet that drives the valve, and is supplied with fuel at a predetermined pressure from a fuel pump. This injector is attached to an engine's intake manifold, etc., and opens a valve to inject fuel when a drive current is applied to its drive coil.

The microcomputer 2 inputs information such as atmospheric pressure and temperature given from the sensor and the output of the signal generator, and calculates the fuel injection position (rotational angular position at which fuel injection is started) and fuel injection time. is calculated, and an injection command signal including information on the calculated fuel injection time is output at the calculated fuel injection position. This injection command signal is, for example, a rectangular wave signal that rises at the fuel injection position and has a signal width equal to the fuel injection time, and the injector drive circuit 7 applies a drive current to the injector while the injection command signal is applied. . The injector opens its valve and injects fuel while a driving current is applied.

[0006]

[Problem to be Solved by the Invention] In the above-mentioned fuel injection device, if the voltage of the power supply of the microcomputer drops and the microcomputer becomes inoperable, fuel injection will not be performed, so it is difficult to operate the engine. become unable to do so.

[0007] Furthermore, in order to enable control by a microcomputer in an internal combustion engine that is started by a manual starter without being equipped with a battery, it is necessary to operate the microcomputer using a generator driven by the internal combustion engine as a power source. However, in this case, the microcomputer cannot operate normally until the output voltage of the generator is established when starting the engine, which may make it difficult to start the engine. For example, when the rotational speed N [rpm] shows the change shown in FIG. 12 as time t passes when the internal combustion engine is started, the minimum rotational speed necessary to obtain the generator output to operate the microcomputer is Nm. Assuming that, if the engine speed can only be increased to Nr as shown in the diagram using the manual starter,
Since the microcomputer cannot be operated, fuel cannot be injected and the engine cannot be started.

Furthermore, even if the power supply to the microcomputer is secured, if the CPU malfunctions or if the cylinders of a multi-cylinder internal combustion engine cannot be discriminated, the microcomputer may not be able to perform accurate control. become unable. For example, when obtaining information about the rotational angular position of the engine using an inductor-type signal generator that generates a signal by applying magnetic flux changes to the signal generator using a reluctor installed on the rotor side, Reluctors with different values are installed to generate signals with different generation intervals for each cylinder, and the cylinders are identified by measuring the generation intervals of the signals corresponding to each cylinder. If the signal generation interval becomes incorrect due to speed fluctuations, it becomes impossible to discriminate between cylinders, and the microcomputer becomes unable to correctly calculate the fuel injection time.

An object of the present invention is to provide an injector driving method and a driving device for an internal combustion engine, which can inject fuel and operate the engine even when control by a microcomputer is not possible. There is a particular thing.

0010

[Means for Solving the Problems] The injector driving method of the present invention includes a microcomputer that calculates the fuel injection time according to predetermined control conditions, and a signal generator that generates a signal at a predetermined rotation angle position of the engine. A signal generating circuit is provided that outputs a signal for determining the fuel injection time based on the output. When the microcomputer is in a normal operating state, a driving current is applied to the injector during the fuel injection time calculated by the microcomputer, and when the microcomputer is not operating normally, a driving current is provided from the signal generation circuit. A drive current is applied to the injector for a fuel injection time determined by the signal.

The injector drive device of the present invention includes a microcomputer that calculates a fuel injection time based on various detected control conditions and outputs a main injection command signal containing information on the calculated fuel injection time; a preliminary injection command signal generating circuit which is provided separately from the microcomputer and generates a preliminary injection command signal including information on a predetermined fuel injection time; and a preliminary injection command signal generating circuit which responds to the main injection command signal when the main injection command signal is generated. and causing a drive current to flow through the injector for a fuel injection time given by the main injection command signal,
and an injector drive circuit that responds to the preliminary injection command signal and supplies a drive current to the injector during the fuel injection time given by the preliminary injection command signal when the main injection command signal is not generated.

The injector drive device of the present invention also includes a microcomputer that calculates a fuel injection time based on various detected control conditions and outputs a main injection command signal containing information on the calculated fuel injection time; A preliminary injection command signal generation circuit is provided separately from the microcomputer and generates a preliminary injection command signal including information on a predetermined fuel injection time, and a preliminary injection command signal generating circuit is provided which generates a preliminary injection command signal including information on a predetermined fuel injection time. a switching circuit that outputs a drive signal containing information on the fuel injection time based on the preliminary command signal; and a switching circuit that outputs a drive signal containing information on the fuel injection time based on the preliminary command signal when the microcomputer is not operating normally; It can also be configured with an injector drive circuit that causes a drive current to flow through the injector in accordance with an output drive signal.

[0013] In this case, the microcomputer is configured to output a switching signal when the microcomputer is operating normally, and when the switching signal is given, the fuel is injected based on the main injection command signal. The switching circuit can be configured to output a drive signal including information on the injection time, and output a drive signal including information on the fuel injection time based on the preliminary injection command signal when the switching signal is not given.

Further, a voltage detection circuit is provided which detects the power supply voltage of the microcomputer and outputs a switching signal when the detected voltage exceeds a level that allows the microcomputer to operate normally, and the switching signal is provided. At times, a drive signal including information on the fuel injection time is output based on the main injection command signal, and when the switching signal is not given, a drive signal including information on the fuel injection time is output based on the preliminary command signal. A switching circuit can also be configured.

Furthermore, the above switching signal may be applied externally.

[0016] In order to be able to drive the injector even when the power of the microcomputer is low,
It is necessary to drive the preliminary injection command signal generation circuit with a power source different from the power source of the microcomputer.

[0017] Detection of abnormal operation of the microcomputer due to a cause other than a drop in power supply voltage may be performed by a known method of incorporating a check program into the program for operating the microcomputer. I can do it.

[0018]

[Operation] With the above configuration, when the microcomputer does not operate normally due to a drop in the power supply voltage of the microcomputer, malfunction of the CPU, etc., a signal obtained from a signal generation circuit provided separately from the microcomputer is generated. This allows the fuel injection time to be determined and the drive current to flow through the injector. Therefore, even when the microcomputer does not operate normally, the injector can be operated to operate the engine.

[0019]

[Embodiment] Fig. 1 shows an embodiment of the present invention. In the figure, 2 is a microcomputer, and this microcomputer controls various control conditions (atmospheric pressure, temperature of each part of the engine) detected by sensors. , ambient temperature, throttle opening, etc.) and outputs a main injection command signal Vi containing information on the fuel injection time at the calculated predetermined fuel injection position.

Reference numeral 100 denotes a preliminary injection command signal generating circuit which is provided separately from the microcomputer 2 and generates a preliminary injection command signal Vi'. a signal generator 3, which converts the signal obtained from the signal generator 3 into a predetermined waveform, and a waveform shaping circuit 4, which obtains engine rotation angle information from the output signal of the waveform shaping circuit 4 and determines a predetermined fuel injection position. and a signal generation circuit 5 which outputs a preliminary injection command signal including information on fuel injection time.

The illustrated signal generator 3 is an inductor-type generator having a rotor 3A attached to the rotating shaft of the engine and a signal generator 3B. The signal generator 3B includes an iron core 3b2 around which a signal coil 3b1 is wound, and a permanent magnet (not shown) that flows magnetic flux through the iron core.
A magnetic pole portion 3b3 provided at the tip of b2 is opposed to the rotor 3A. Rotor 3A is reluctor (inductor) 3
a, and the reluctor has a magnetic pole part 3b of the signal generator.
Due to changes in the magnetic flux that occur when starting and ending the facing, respectively, pulsed signal voltages Vs1 and Vs2 with different polarities are induced in the signal coil 3b1.

In this embodiment, among the signals of different polarities obtained from the signal coil 3b1, the position where the signal Vs1 generated first reaches the threshold level is the position suitable for the fuel injection position when starting the engine. The positional relationship between the reluctor 3a and the magnetic pole part 3b3 of the signal generator is set so that they match, and the period from when the signal voltage Vs1 reaches the threshold level to when the next generated signal voltage Vs2 reaches the threshold level The length of the reluctor 3a is set so that the angular width corresponds to a predetermined fuel injection time.

The waveform shaping circuit 4, for example, has a signal voltage Vs1.
It outputs a rectangular wave signal Vq that lasts from when the signal voltage Vs2 reaches the threshold level until the signal voltage Vs2 reaches the threshold level. The rising position of this rectangular wave signal Vq is the fuel injection position, and the signal width of the rectangular wave signal corresponds to the fuel injection time at the time of starting the engine.

The signal generating circuit 5 receives the rectangular wave signal Vq as an input and outputs a rectangular wave signal having a signal width corresponding to the fuel injection time when control by a microcomputer cannot be performed as a preliminary injection command signal Vi'. .

Note that if the output of the waveform shaping circuit 4 can be used as it is as the preliminary injection command signal, the signal generating circuit 5 is omitted.

Reference numeral 6 designates an injector that includes a drive coil 6a and opens a valve to inject fuel while a drive current is applied to the drive coil 6a. Reference numeral 7 designates an injector drive circuit that causes a drive current to flow through the injector 6.

When the main injection command signal Vi is generated, the injector drive circuit 7 supplies a drive current to the injector 6 for a fuel injection time given by the main injection command signal in response to the main injection command signal Vi, and outputs the main injection command. When no signal is generated, a drive current is caused to flow through the injector 6 during the fuel injection time given by the preliminary injection command signal Vq in response to the preliminary injection command signal Vq.

When the main injection command signal Vi and the preliminary injection command signal Vq rise at the fuel injection position and are rectangular wave signals whose signal width corresponds to the fuel injection time, the injector drive circuit 7 outputs the main injection command. It can be constituted by a switch that becomes conductive when triggered by a command signal that occurs first among the signal and the preliminary injection command signal. In this case, priority is given to the main injection command signal Vi, and when the main injection command signal is generated, a drive current is passed through the injector for the injection time given by the main injection command signal, and when the main injection command signal is not generated, the drive current is passed through the injector. In order to cause the drive current to flow through the injector only for the time given by the preliminary injection command signal, for example, the injection time given by the preliminary injection command signal must be etc.), and the preliminary injection command signal may be generated after the position where the main injection command signal giving the shortest injection time is generated.

Furthermore, the injector drive circuit is provided with a drive current control switch that becomes conductive to flow a drive current to the injector when the main injection command signal or the preliminary injection command signal is applied, and the switch is connected to the input terminal of the preliminary injection command signal. A command signal switch circuit is provided between the control terminal of the drive current control switch, and when the main injection command signal is generated, the command signal switch circuit is turned off to control the drive current using only the main injection command signal. The command signal switch circuit may be turned on when the main injection command signal is not generated, and the drive current control switch may be made conductive by the preliminary injection command signal.

The main injection command signal and the preliminary injection command signal may be any signal containing information on a predetermined fuel injection time, and do not necessarily need to be rectangular wave signals. For example, a pair of pulse signals consisting of a pulse signal generated at the fuel injection start position and a pulse signal generated at the fuel injection end position may be used as the injection command signal. Each injection command signal can take various forms depending on the configuration of the injector drive circuit.

The main injection command signal and the preliminary injection command signal do not have to have the same waveform, and may have different waveforms. for example,
The main injection command signal is a rectangular wave signal that rises at the fuel injection position and whose signal width corresponds to the fuel injection time, and the preliminary injection command signal is a signal Vs obtained from the signal generator 3.
It is also possible to use pulse signals obtained by waveform shaping each of Vs1 and Vs2. The pulse signals obtained by waveform shaping the signals Vs1 and Vs2 are sent to the injector drive circuit 7.
If the driving current is caused to flow through the injector 6 by applying the same amount of fuel, the injector will inject fuel intermittently, but this will not affect the operation of the engine.

In the example shown in FIG. 1, the signal generator 3 which gives rotation angle information to the microcomputer is also used as a signal generator to obtain a preliminary injection command signal, but as shown in FIG. In addition to the signal generator 3 that provides rotation angle information to the computer, a signal generator 3' for obtaining a preliminary injection command signal is separately provided.
The preliminary injection command signal may be obtained by waveform-shaping the output signal of ' and generating the signal by the signal generation circuit 5 as necessary.

Various other embodiments of the present invention will be shown below, but in order to simplify the explanation, in the following embodiments, both the main injection command signal and the preliminary injection command signal are expressed in a rectangular shape that rises at the fuel injection position. It is assumed that the signal is wave-like, and the width of each signal corresponds to the fuel injection time.

FIG. 3 shows another embodiment of the present invention, in which 1 is a battery power source that outputs a DC constant voltage using a battery as a power source, 2 is a microcomputer driven by the battery power source 1, and 3 is a battery power source that outputs a DC constant voltage. 4 is an inductor-type signal generator that is driven by the internal combustion engine and generates a signal at a predetermined rotation angle position of the engine; 4 is a waveform shaping circuit that shapes the output signal of the signal generator 3; and 6 is a drive coil 6a. The injector 7 provided is an injector drive circuit that applies a drive current to the drive coil 6a of the injector while the drive signal Vd is applied.

In this embodiment as well, among the signals of different polarities obtained from the signal coil 3b1, the signal V generated first is
The positional relationship between the reluctor 3a and the magnetic pole portion 3b3 of the signal generator is set so that the position where s1 reaches the threshold level corresponds to a position suitable for the fuel injection position at engine startup, and the signal voltage Vs1 is The length of the reluctor 3a is set so that the angular width from when the threshold level is reached until the next signal voltage Vs2 reaches the threshold level corresponds to the fuel injection time.

The waveform shaping circuit 4 generates a rectangular wave signal V that lasts from when the signal voltage Vs1 reaches the threshold level to when the signal voltage Vs2 reaches the threshold level.
Output q. The rising position of this rectangular wave signal Vq coincides with the fuel injection position, and the signal width of the rectangular wave signal corresponds to the fuel injection time.

In this example, when the microcomputer 2 is operating normally, the switching signal Vx is output from the output port 2a of the microcomputer. That is, in this example, the switching signal generating means is realized by software of a microcomputer.

The microcomputer 2 receives the outputs of various sensors for detecting atmospheric pressure, ambient temperature, temperature of each part of the engine, throttle angle of the engine, etc., and the output V of the waveform shaping circuit 4.
q is input. The microcomputer 2 determines the fuel injection position and injection time based on control conditions such as atmospheric pressure, temperature, and throttle angle obtained from the outputs of various sensors, and rotation angle information obtained from the output signals of the signal generator 3. A rectangular waveform main injection command signal Vi having a signal width corresponding to the calculated injection time at the calculated fuel injection position is output from the output port 2b.

In this example, the output signal of the waveform shaping circuit 4 is used as it is as the preliminary injection command signal Vi', and this preliminary injection command signal Vi' is sent to the switching circuit 8 together with the main injection command signal Vi obtained from the microcomputer 2.
has been entered. The output signal of the switching circuit 8 is the drive signal V
d to the injector drive circuit 7.

The switching circuit 8 uses the switching signal Vx as a control signal and sends a signal having the same waveform as the preliminary injection command signal Vi' to the drive signal Vd when the switching signal is not applied.
is applied to the input terminal 7a of the injector drive circuit 7 as
When the switching signal Vx is given, the injector drive circuit 7 uses a signal with the same waveform as the main injection command signal Vi output from the microcomputer 2 as the drive signal Vd.
is applied to the input terminal 7a of.

In this embodiment, a magnet generator 9 driven by the internal combustion engine is also provided, and the output of the generator 9 is given to a power supply circuit 10, and the DC voltage obtained from the power supply circuit 10 is used to drive the injector. A voltage is applied to the power supply terminal 7b of the circuit 7.

Although not shown, a charging output is provided from the generator 9 to the battery of the battery power source 1 through a battery charging circuit.

In the above embodiment, when the microcomputer 2 is in a normal operating state, the switching signal Vx is output from the microcomputer 2, so the switching circuit 8 controls the main injection output from the microcomputer 2. A signal with the same waveform as the command signal Vi is used as the drive signal Vd.
It is given to the injector drive circuit 7 as a signal. Therefore, the injector 6 injects fuel during the injection time calculated at the fuel injection position calculated by the microcomputer,
Operate the engine in optimal condition.

On the other hand, if the battery voltage drops or the CPU malfunctions, the microcomputer 2
When the microcomputer 2 is not operating normally, the microcomputer 2 stops outputting the switching signal Vx. Therefore, the switching circuit 8 supplies a signal having the same waveform as the preliminary injection command signal Vi' obtained from the waveform shaping circuit 4 to the injector drive circuit 7 as the drive signal Vd. Therefore, even when the microcomputer does not operate normally, the injector can be operated to supply fuel to the engine and operate the engine.

As shown in the embodiment shown in FIG. 3, if driving power is supplied from the generator 9 to the ejector drive circuit 7, even if the microcomputer does not operate normally due to a drop in the power supply voltage, the injector drive circuit 7 can still be driven. Since the circuit 7 is supplied with drive power from the generator 9 through the power supply circuit 10, the injector drive circuit 7 supplies a drive current to the injector 6 while the drive signal Vd is being generated.

Therefore, for example, even if the battery power supply 3 is unable to operate the microcomputer normally due to a drop in battery voltage, the injector can be operated to start the engine. Once the engine is started, the battery is charged by the generator 9 attached to the engine, so that the microcomputer 2 can operate normally and the engine can be operated without any trouble.

In the embodiment shown in FIG. 3, the waveform shaping circuit 4
If the switching circuit 8 includes active elements such as transistors, it is needless to say that power for these circuits must be supplied from the power supply circuit 10.

In the above embodiment, the microcomputer 2 is driven by the battery power source 1, but as shown in FIG.
As shown in FIG. 2, it can also be driven by the output of a generator 9 driven by an internal combustion engine. In the example of FIG.
The outputs of two different power generation coils 9A and 9B provided in the generator 9 are input to power supply circuits 10A and 10B, respectively, and the DC constant voltage obtained from these power supply circuits 10A and 10B, respectively, is applied to the power supply terminal of the injector drive circuit 7. and is applied to the power terminal of the microcomputer 2. Other points are similar to the embodiment shown in FIG.

In the embodiment shown in FIG. 4, the number of turns of the generator coil 9A is set so as to generate sufficient output to drive the injector drive circuit 7 at a rotation speed Nr or less shown in FIG. 12 when the engine is started. has been done. Also, the power generation coil 9
It is assumed that the number of turns of B is set so as to output a voltage that operates the microcomputer 2 at the rotational speed Nm shown in FIG.

In this case, when starting the engine, the switching signal V
Since x is not generated, the switching circuit 8 provides the injector drive circuit 7 with a signal having the same waveform as the preliminary injection command signal Vi' obtained from the waveform shaping circuit 4 as the drive signal Vd. Further, the injector drive circuit 7 is given a predetermined drive power from the power generation coil 9A. Therefore, a driving current is applied to the injector 6 to inject fuel and start the engine. After the engine starts, when the output of the generator coil 9B reaches a level that causes the microcomputer 2 to operate, the microcomputer 2 outputs the switching signal Vx, so the switching circuit 8 outputs the main injection command signal Vi given from the microcomputer 2. A drive signal Vd having the same waveform as ' is applied to the injector drive circuit 7. Therefore, from now on, the fuel injection time is controlled by the microcomputer. This embodiment is useful for engines without batteries.

In the above embodiment, the switching signal generating means is realized by a microcomputer and the switching signal Vx is outputted from the microcomputer 2. However, as shown in FIG.
As shown in the figure, a voltage detection circuit 11 is provided which detects the voltage of the power supply of the microcomputer and outputs a switching signal Vx when the power supply voltage is equal to or higher than a set value (a value necessary for normal operation of the microcomputer). Therefore, this voltage detection circuit 11 may be used as a switching signal generating means.

FIG. 6 shows that in the embodiment of FIG. 4, the output voltage of the power supply circuit 10B that drives the microcomputer is detected and the output voltage is set to a set value (a value necessary for normal operation of the microcomputer). This is an example in which a voltage detection circuit 11 is provided that outputs a switching signal Vx when the above conditions occur.

FIG. 7 shows a switching signal V applied to the switching circuit 8 from the outside.
This shows an example in which x is given. In this case, the switching signal Vx is constantly supplied during normal operation, and its supply is stopped by manual switch operation or the like when an abnormal situation occurs such as the microcomputer malfunctioning and the engine running out of control.

By applying the switching signal Vx from the outside in this way, when the engine status becomes abnormal due to a malfunction of the microcomputer, the operation based on the injection command signal provided by the output of the signal generator 3 will be changed. Since it can be switched, safety can be increased.

In each of the above embodiments, when the microcomputer is not operating, the rectangular wave signal obtained from the waveform shaping circuit 4 is directly applied to the switching circuit 8 as a preliminary injection command signal. The fuel injection time becomes constant, and the fuel injection time cannot be set to a length commensurate with atmospheric pressure and engine temperature. Therefore, for example, if the signal width of the square wave signal Vq (preliminary injection command signal) is set to make it easier to start the engine in warm weather,
In cold weather, there is a possibility that the fuel injection time at the time of starting is insufficient, making it impossible to properly start the engine.

FIG. 6 shows an embodiment that solves this problem. In this embodiment, a signal width correction circuit 12 is inserted between the waveform shaping circuit 4 and the signal switching circuit 8. This signal width correction circuit 12 corresponds to the signal generation circuit 5 shown in the embodiment of FIG.

The signal width correction circuit 12 inputs information obtained from a sensor that detects control conditions such as atmospheric pressure and engine temperature, and changes the width of the rectangular wave signal obtained from the waveform shaping circuit based on the information. Then, a preliminary injection command signal Vi' having a signal width corresponding to a fuel injection time suitable for the engine state at that time is output.

In the illustrated example, temperature information obtained from a temperature sensor that detects the temperature of the engine is input to the signal width correction circuit 12. By providing such a correction circuit, even if the microcomputer does not operate normally, a rectangular wave signal with a signal width commensurate with the engine temperature can be supplied from the signal generator 3 side as the injection command signal, so that the engine can be I can drive without any problems.

FIG. 9 shows a specific example of the signal width correction circuit 12. In this example, the inverter IN and the resistor R1
and R2, diode D1, and capacitor C,
A signal width correction circuit 12 is constituted by the comparator CP. In addition, a temperature-sensitive resistance element Rt having a positive temperature coefficient
h constitutes a temperature sensor that detects the temperature of the engine. In this embodiment, when the rectangular wave signal Vq is input to the inverter IN, the signal V is output to the output side of the inverter.
A signal Vq' is obtained by inverting q. When this signal Vq' falls to zero, the charge in the capacitor C is instantaneously discharged through the diode D1, and when the signal Vq' rises to a high level, the capacitor C is charged through the resistor R1. The voltage Vc across this capacitor is the resistance R2
It is input to the comparator CP together with the reference voltage Vs obtained across the terminal. Comparator CP has voltages Vc and Vs
When Vs≧Vc, a rectangular waveform pre-injection command signal Vi' which becomes high level is output.

The output of a DC constant voltage power supply circuit (not shown) is applied to both ends of the series circuit of the temperature-sensitive resistance element Rth and the resistor R2, and as the temperature of the engine decreases, the temperature-sensitive resistance element R
When the resistance value of th is low, the reference voltage Vs is high, and when the temperature of the engine is rising and the resistance value of the temperature-sensitive resistance element is high, the reference voltage Vs is low. Therefore, when the engine temperature is low, the signal width of the rectangular wave signal Vqt obtained from the comparator becomes wide, as shown by the waveform shown by the solid line in the figure, and when the engine temperature is high, the signal width is wide, as shown by the waveform shown by the broken line in the figure. Square wave signal Vq
The signal width of t becomes narrower.

Therefore, when the engine temperature is low, the injection time is lengthened, and when the engine temperature is high, the injection time is shortened, so that the engine can be operated without any trouble.

In the example shown in FIG. 8, the signal width correction circuit 12
The output of the signal width correction circuit 12 is inputted to both the microcomputer 2 and the switching circuit 8 as shown in FIG. 10, and the signal width correction is performed. Information contained in the output signal of the circuit 12 may be used for calculations within the microcomputer.

In the embodiments shown in FIGS. 8 and 10, the signal width of the rectangular wave signal obtained from the waveform shaping circuit 4 is corrected according to the engine temperature, but if necessary, the atmospheric pressure , the signal width of the rectangular wave signal may be corrected in accordance with the throttle opening, the engine speed, or the like. In this case, the magnitude of the reference signal Vs may be changed in accordance with the output of the throttle opening sensor or the output of the rotation speed detector.

In each of the above embodiments, the preliminary injection command signal is obtained from the output of the signal generator, but if the magnet generator 9 is attached to the rotating shaft of the engine, the magnet generator 9 By suitably adjusting the magnetic pole configuration of 9 and the phase of its output, the half-wave period of the AC voltage obtained from the magnet generator can be made to coincide with the period during which fuel is injected. If this is possible, the half-wave output of the magnet generator can be used directly as a preliminary injection command signal. Furthermore, the half-wave output of the magnet generator can be shaped into a rectangular wave and used as the preliminary injection command signal, and the signal shaped into the rectangular wave can be given to a signal generation circuit such as a signal width correction circuit. Accordingly, a preliminary injection command signal suitable for various control conditions can be obtained.

In the explanation of the embodiment shown in FIGS. 3 to 10, it was assumed that the main injection command signal and the preliminary injection command signal were a single rectangular wave signal, but these signals and an injection end position, respectively.

Further, the drive signal Vd does not have to have the same waveform as the main injection command signal or the preliminary injection command signal, and a drive signal with any waveform can be used depending on the configuration of the injector drive circuit.

[0067] In order to operate the engine, it is sufficient to inject fuel from the injector only once during one engine cycle, for example, for a predetermined period of time during the intake stroke. Fuel may be injected two or more times at times that do not interfere with engine operation. For example, in a two-stroke engine, fuel may be injected during both the intake stroke and the exhaust stroke. The fuel injected during the exhaust stroke does not enter the cylinder, but stays in the intake port, and then flows into the cylinder together with the fuel injected during the intake stroke, so it is effectively used for engine operation.

In the above embodiment, the fuel injection position and fuel injection time are calculated by the microcomputer, but the microcomputer only calculates the fuel injection time, and the fuel injection position is determined by the timing signal obtained from the signal generator. It is also possible to set it as follows.

[0069]

As described above, according to the present invention, when the microcomputer does not operate normally due to a drop in the power supply voltage of the microcomputer, a malfunction of the CPU, etc. Since the fuel injection time is determined by the signal obtained from the generation circuit and the drive current is passed through the injector, there is an advantage that the injector can be operated and the engine can be operated even when the microcomputer is not operating normally.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a block diagram showing the configuration of another embodiment of the present invention.

FIG. 3 is a block diagram showing the configuration of another embodiment of the present invention.

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

FIG. 5 is a block diagram showing the configuration of another embodiment of the present invention.

FIG. 6 is a block diagram showing the configuration of another embodiment of the present invention.

FIG. 7 is a block diagram showing the configuration of another embodiment of the present invention.

FIG. 8 is a block diagram showing the configuration of another embodiment of the present invention.

FIG. 9 is a circuit diagram showing a configuration example of a signal width correction circuit used in the embodiment of FIG. 8;

FIG. 10 is a block diagram showing the configuration of another embodiment of the present invention.

FIG. 11 is a block diagram showing the configuration of a conventional fuel injection device.

FIG. 12 is a diagram showing an example of a temporal change in the rotational speed at the time of starting the engine.

[Explanation of symbols]

1 Battery power supply 2 Microcomputer 3 Signal generator 3' Signal generator 4 Waveform shaping circuit 5 Signal generation circuit 6 Injector 7 Injector drive circuit 8 Switching circuit 9 Magnet generator 10 Power supply circuit 11 Voltage detection circuit

Claims (7)

[Claims] Claim 1: A signal for determining the fuel injection time based on the output of a microcomputer that calculates the fuel injection time according to predetermined control conditions and a signal generator that generates a signal at a predetermined rotation angle position of the engine. and a signal generation circuit that outputs a signal, and when the microcomputer is in a normal operating state, a drive current is provided to the injector during the fuel injection time calculated by the microcomputer, and when the microcomputer is not operating normally, a driving current is provided to the injector. 1. A method for driving an injector for an internal combustion engine, characterized in that when the injector is in the injector, a driving current is applied to the injector for a fuel injection time determined by a signal obtained from the signal generating circuit. 2. A microcomputer that calculates a fuel injection time based on various detected control conditions and outputs a main injection command signal including information on the calculated fuel injection time, and a microcomputer that is separate from the microcomputer. a preliminary injection command signal generating circuit for generating a preliminary injection command signal including information on a predetermined fuel injection time; A driving current is applied to the injector during the fuel injection time given by the signal, and when the main injection command signal is not generated, the injector is driven for the fuel injection time given by the preliminary injection command signal in response to the preliminary injection command signal. 1. An injector drive device for an internal combustion engine, comprising an injector drive circuit that allows current to flow. 3. A microcomputer that calculates a fuel injection time based on various detected control conditions and outputs a main injection command signal including information on the calculated fuel injection time, and a microcomputer that is separate from the microcomputer. a preliminary injection command signal generating circuit which generates a preliminary injection command signal including information on a predetermined fuel injection time; and a preliminary injection command signal generation circuit which generates a preliminary injection command signal including information on a predetermined fuel injection time; a switching circuit that outputs a drive signal containing information, and outputs a drive signal containing information on fuel injection time based on the preliminary command signal when the microcomputer is not operating normally; and a drive output from the switching circuit. An injector drive device for an internal combustion engine, comprising an injector drive circuit that causes a drive current to flow through the injector in response to a signal. 4. A microcomputer that calculates a fuel injection time based on various detected control conditions and outputs a main injection command signal including information on the calculated fuel injection time, and a microcomputer that is separate from the microcomputer. a preliminary injection command signal generation circuit that generates a preliminary injection command signal including information on a predetermined fuel injection time based on the output of a signal generator that generates a signal at a predetermined rotation angle position of the engine; and a microcomputer. As an input, the switching signal output from the microcomputer when the microcomputer is operating normally,
When the switching signal is given, a drive signal including fuel injection time information is output based on the main injection command signal, and when the switching signal is not given, the fuel injection time is output based on the preliminary command signal. An injector drive device for an internal combustion engine, comprising: a switching circuit that outputs a drive signal containing information; and an injector drive circuit that causes a drive current to flow through the injector in accordance with the drive signal output from the switching circuit. 5. A microcomputer that calculates a fuel injection time based on various detected control conditions and outputs a main injection command signal including information on the calculated fuel injection time, and a microcomputer that is separate from the microcomputer. a preliminary injection command signal generation circuit that generates a preliminary injection command signal including information on a predetermined fuel injection time based on the output of a signal generator that generates a signal at a predetermined rotation angle position of the engine; a voltage detection circuit that detects the power supply voltage of the computer and outputs a switching signal when the detected voltage is at a level higher than the level that allows the microcomputer to operate normally; Sometimes, a drive signal including information on fuel injection time is output based on the main injection command signal, and when the switching signal is not given, a drive signal including information on fuel injection time is output based on the preliminary command signal. An injector drive device for an internal combustion engine, comprising: a switching circuit; and an injector drive circuit that causes a drive current to flow through the injector in accordance with a drive signal output from the switching circuit. 6. A microcomputer that calculates a fuel injection time based on various detected control conditions and outputs a main injection command signal including information on the calculated fuel injection time, and a microcomputer that is separate from the microcomputer. a preliminary injection command signal generation circuit that generates a preliminary injection command signal including information on a predetermined fuel injection time based on the output of a signal generator that generates a signal at a predetermined rotation angle position of the engine; With the given switching signal as input, when the switching signal is given, a drive signal including fuel injection time information is output based on the main injection command signal, and when the switching signal is not given, the preliminary command is output. The present invention is characterized by comprising a switching circuit that outputs a drive signal including information on fuel injection time based on the signal, and an injector drive circuit that causes a drive current to flow through the injector in accordance with the drive signal output from the switching circuit. Injector drive device for internal combustion engines. 7. The injector drive device for an internal combustion engine according to claim 2, wherein the preliminary injection command signal generation circuit is driven by a power source different from a power source of the microcomputer.