JPH04231643A - Fuel injection device for internal combustion engine - Google Patents

Abstract

PURPOSE:To enable stable operation of the engine even in the case of a failure of a microcomputer for controlling the injector. CONSTITUTION:An injection command signal generator circuit 7 is provided which generates an injection command signal Vhi for starting the engine and an injection command signal Vhn for normal operation of the engine. When the microcomputer comes into a failure, the injection command signal for normal operation is supplied, as drive signal Vd, to an injector driving circuit 3 to drive an injector 2.

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 supplying 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.

[0004] The microcomputer 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. It calculates and outputs an injection command signal including information on the calculated fuel injection time 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.

[0005]

[Problems to be Solved by the Invention] In the above fuel injection device, if the voltage of the power supply of the microcomputer is low and the microcomputer is in a state where it does not operate, fuel injection will not be performed. There was a problem that if the power supply voltage of the computer was low, the engine could not be started.

[0006] 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 the engine is started, so there is a problem in that it becomes difficult to start the engine.

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, it is necessary to perform control using the microcomputer appropriately. become unable to do so. 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. This is particularly likely to occur when the engine is started, since the rotational speed fluctuates rapidly.

An object of the present invention is to provide a fuel injection device for an internal combustion engine that is capable of driving an injector even when a microcomputer is in a state where it cannot operate normally.

[0009]

[Means for solving the problem] In order to make it possible to start the engine when the power supply voltage of the microcomputer is low, a hard circuit is required to obtain an injection command signal using the output of a signal generator attached to the internal combustion engine. If the microcomputer does not operate normally due to a low power supply voltage or the like, the injector may be driven by the injection command signal obtained from this hardware circuit.

In this case, in order to make the engine start smoothly, it is necessary to set the signal width of the injection command signal for hard control to a size corresponding to the injection time suitable for starting the engine. During normal startup, the injection time is lengthened and the fuel is set to be rich.

In this specification, an injection command signal generated by a microcomputer using software;
In order to distinguish it from the injection command signal generated by the hard circuit using the output of the signal generator, the injection command signal generated by the microcomputer is called the injection command signal for software control. The injection command signal generated by this will be referred to as the injection command signal for hardware control.

By the way, the injection command signal generated using the output signal of the signal generator is required not only when starting the engine, but also when the microcomputer malfunctions.
Alternatively, even if the power supply of the microcomputer fails, it is desirable to be able to drive the injector using the injection command signal for hardware control. In this case, if a hard control injection command signal with a signal width suitable for engine startup is used, the fuel may become too rich, resulting in unstable engine operation or insufficient engine output. A problem arises.

Therefore, in the present invention, an injector and a microcomputer that calculates a fuel injection time based on various detected control conditions and outputs an injection command signal for software control including information on the calculated fuel injection time are provided. is installed separately from the microcomputer, and outputs an injection command signal for hard control during engine startup, including information on the fuel injection time suitable for starting, and during steady engine operation, it outputs an injection command signal suitable for steady engine operation. An injection command signal generation circuit for hard control outputs an injection command signal for hard control during steady state, including information on the fuel injection time, and an injection command signal for soft control when the microcomputer is in a normal operating state. A drive current is passed through the injector during the fuel injection time given by the hardware control injection command signal output from the hardware control injection command signal generation circuit when the microcomputer is not operating normally. An injector drive current supply control circuit is provided to supply a drive current to the injector between the two injectors.

The injector drive current supply control circuit includes an injector drive circuit that supplies a drive current to the injector during the fuel injection time given by the drive signal when a drive signal including information on the fuel injection time is input, and a microcontroller. The switching signal generation means generates a switching signal when the computer is operating normally, and the injection command signal for hardware control obtained from the injection command signal generation circuit for hardware control when no switching signal is generated is used as a drive signal. and a switching circuit that supplies an injection command signal for soft control to the injector drive circuit as a drive signal when a switching signal is generated.

Further, in the present invention, the switching signal is allowed to be applied to the switching circuit while the hardware control injection command signal generation circuit is generating the hardware control injection command signal for starting, and the hardware control A switching signal supply control circuit can be further provided that prohibits the switching signal from being applied to the switching circuit when the control injection command signal generation circuit is generating the hard control injection command signal for normal operation.

The present invention further includes a temperature sensor that detects temperature information necessary for determining fuel injection time, and a hardware control signal that is obtained from a hardware control injection command signal generation circuit in accordance with the information obtained from the temperature sensor. A temperature correction circuit may be provided to change the information on the fuel injection time included in the injection command signal.

The present invention also includes a throttle sensor that detects the throttle opening of the internal combustion engine, and a signal correction circuit that changes the fuel injection time information included in the injection command signal for hardware control according to the throttle opening information obtained from the throttle sensor. It is also possible to provide more. Preferably, the hardware control injection command signal generation circuit and the microcomputer are driven by separate power supplies.

[0018] In the present invention, "during steady operation" means an operating state after the engine has been started (an operating state other than the time of starting), and includes a warm-up operating state and an idling state.

[0019]

[Operation] With the above configuration, if the microcomputer does not operate normally when starting the engine, the drive current is supplied to the injector for the fuel injection time suitable for starting given by the injection command signal for hard control during starting. Given. Therefore, even when the microcomputer is not operating normally, the injector can be operated to start the engine.

[0020] Furthermore, when the engine is to be operated in a steady state in a state where the microcomputer is not operating normally, the driving current is applied to the injector during the fuel injection time suitable for steady-state operation given by the injection command signal for hard control during steady-state operation. is given.

[0021] If the fuel injection time given by the hard control injection command signal for starting is kept constant, depending on the engine temperature or ambient temperature, the fuel injection time suitable for starting the engine may not be obtained. , it may be difficult to start the engine. In this case, a temperature sensor detects the temperature information necessary to determine the fuel injection time, and the fuel injection time information given by the hardware control injection command signal for starting is changed according to the information obtained from the temperature sensor. By installing a temperature correction circuit, the fuel injection time can be adjusted according to the temperature, so the optimal injection time can be obtained according to the temperature conditions, and the engine can be started reliably even in cold regions. can.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the present invention, in which reference numeral 1 denotes a signal generator which is driven by an internal combustion engine and generates a signal at a predetermined rotation angle position of the engine. This signal generator 1 is connected to a rotor 1 attached to the rotating shaft of an engine.
This is a well-known inductor type generator consisting of a signal generator A and a signal generator 1B, and a rotor 1 is provided with a reluctor 1a. The signal generator 1B includes a signal coil 1b wound around an iron core having a magnetic pole portion facing the rotor, and a permanent magnet that generates a magnetic flux that interlinks with the signal coil. Pulse signals with different polarities are induced in the signal coil 1b when facing each other and when the facing ends, respectively.

Reference numeral 2 denotes an injector having a needle valve for opening and closing a nozzle and an electromagnet for opening and closing the valve. Fuel is supplied to this injector at a predetermined pressure from a fuel pump. The injector 2 has a drive coil 2a that excites an electromagnet, and opens a valve to inject fuel while a drive current is applied to the drive coil.

Reference numeral 3 denotes an injector drive circuit that allows a drive current to flow through the drive coil 2a of the injector while the drive signal Vd is being input, and this drive circuit is comprised of a switch circuit that is closed only while the drive signal is being applied.

Reference numeral 4 denotes a microcomputer, and this microcomputer uses various control conditions (throttle angle, engine temperature, etc.) obtained from the outputs of various sensors attached to the internal combustion engine and a signal generator according to a predetermined program. The fuel injection position and injection time are calculated based on the rotation angle information and speed information obtained from the output signal of. The microcomputer 4 has an output port A1, and outputs an injection command signal Vs for software control whose signal width corresponds to the fuel injection time and whose rising position corresponds to the fuel injection position.
Output from.

5 is a waveform shaping circuit that converts the output signal of the signal generator 1 into a rectangular wave signal, and the rectangular wave signal obtained from this waveform shaping circuit is input to the input port B1 of the microcomputer 4 as a signal giving rotation angle information. It is also given to the hardware control injection command signal generation circuit 7.

The hardware control injection command signal generation circuit 7 includes:
An injection command signal Vhi for hard control at startup, which rises at the injection position at the time of engine startup in synchronization with the output signal of the signal generator, and has a signal width corresponding to an injection time suitable for startup, and a steady-state operation of the engine. The hard control injection command signal Vhn for steady state operation is generated and has a signal width corresponding to an injection time suitable for steady state operation.

Hard control injection command signals Vhi and Vh
n is given to the switching circuit 9 through the signal selection circuit 8.

In this embodiment, a magnet generator 10 is attached to the engine to drive the microcomputer and injector drive circuit 3. This magnet generator consists of a magnet rotor 10a attached to the rotating shaft of the engine, and a stator equipped with generator coils 10b and 10c, and the outputs of the generator coils 10b and 10c are input to power supply circuits 11 and 12, respectively. has been done.

The power supply circuits 11 and 12 are DC constant voltage circuits that rectify the AC outputs of the generator coils 10b and 10c and output constant DC voltage, and the DC voltage obtained from the power supply circuit 11 is connected to the power terminal of the microcomputer 4. Furthermore, the DC voltage obtained from the power supply circuit 12 is applied to the power supply terminals of the injector drive circuit 3, respectively.

The signal selection circuit 8 selects the injection command signal Vhi for hard control at startup when starting the internal combustion engine and outputs it as the injection command signal Vh for hard control, and outputs the injection command signal Vhn for hard control during steady operation during steady operation. is selected and output as the injection command signal Vh for hardware control.

The signal selection circuit 8 may select a signal by operating a manual switch, or may select a signal by a switch that automatically operates when the microcomputer malfunctions. It also detects the engine rotation speed and automatically selects the injection command signal for hard control at startup when the rotation speed is lower than the set value, and injects the injection command signal for hard control at startup when the rotation speed exceeds the set value. The command signal may be automatically selected.

The microcomputer 4 also has an output port A2, and when the induced voltage of the power generation coil 10b is established and the microcomputer 4 is operating normally, it outputs a switching signal Ve from the output port A2 to generate power. The induced voltage of the coil 10b is low, and the microcomputer 4
The output of the switching signal Ve is stopped when the microcomputer is unable to operate due to insufficient power supply voltage or when the microcomputer malfunctions. Detection of abnormal operation of the microcomputer can be performed by a known method of incorporating a checking program into the program that operates the microcomputer. In this embodiment, the switching signal generating means is realized by software that operates the microcomputer 4.

The switching signal Ve' is applied to the switching circuit 9 via the switching signal supply control circuit 13. The switching signal supply control circuit 13 outputs the switching signal V when the signal selection circuit 8 selects the injection command signal for hard control at the time of starting.
e is allowed to be applied to the switching circuit 9, and when the signal selection circuit 8 selects the injection command signal Vhn for hard control during normal operation, the switching signal Ve is prohibited from being applied to the switching circuit. This switching signal supply control circuit 13 has a signal selection circuit which closes when the signal selection circuit 8 selects the injection command signal for hard control during startup and opens when the injection command signal for hard control during steady state is selected. It can be configured by a switch that operates in conjunction with the selection operation of 8.

The switching circuit 9 supplies the injector drive circuit with a signal having the same waveform as the hard control injection command signal Vh outputted from the selection circuit 8 when the switching signal Ve is not applied as the drive signal Vd, and outputs the switching signal as a drive signal Vd. is given, a signal having the same waveform as the soft control injection command signal output from the microcomputer is given to the injector drive circuit as the drive signal Vd.

In this embodiment, the signal generator 1, the waveform shaping circuit 6, and the injection command signal generation circuit 7 for hardware control are provided separately from the microcomputer 4, and are configured to be suitable for starting the engine. Outputs an injection command signal Vhi for hard control at startup that includes information on the fuel injection time suitable for steady engine operation, and outputs an injection command signal for hard control during steady state operation that includes information on a fuel injection time suitable for steady operation of the engine. V
Injection command signal generation circuit 10 for hardware control that outputs hn
0 is configured.

Furthermore, the switching signal generating means, the signal selection circuit 8, the switching circuit 9, and the injector drive circuit 3 control the amount of fuel given by the soft control injection command signal when the microcomputer is in a normal operating state. A drive current is applied to the injector during the injection time, and when the microcomputer is not operating normally, the drive current is applied to the injector during the fuel injection time given by the hardware control injection command signal output from the hardware control injection command signal generation circuit. An injector drive current supply control circuit 101 is configured to flow a drive current.

The injection command signal for hard control and the injection command signal for soft control 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 injection command signal for soft control and the injection command signal for hard control do not have to have the same waveform and may be different. For example, the soft control injection command signal is a rectangular wave signal that rises at the fuel injection position and the signal width corresponds to the fuel injection time, and the hard control injection command signal is the signal Vs1 obtained from the signal generator 3. It is also possible to use pulse signals obtained by waveform shaping each of Vs2 and Vs2. If the pulse signals obtained by waveform shaping the signals Vs1 and Vs2 are given to the injector drive circuit 3 to cause a drive current to flow through the injector 2, the injector will inject fuel intermittently; There is no problem with engine operation.

In the example shown in FIG. 1, the signal generator 1 that provides rotation angle information to the microcomputer is also used as a signal generator to obtain an injection command signal for hardware control. In addition to the signal generator 1 that supplies the signal, a signal generator for obtaining an injection command signal for hardware control is provided separately, and the output signal of this signal generator is waveform-shaped and then generated by the injection command signal generation circuit 7 for hardware control. The hardware control injection command signals Vhi and Vhn may be obtained by generating signals.

To simplify the explanation, in this embodiment, both the injection command signal for soft control and the injection command signal for hard control are rectangular wave signals that rise at the fuel injection position, and the width of each signal corresponds to the fuel injection time. It is assumed that it corresponds to

Further, the drive signal Vd may be any signal that instructs to flow a drive current from the injector drive circuit 3 to the injector 2 during the fuel injection time given by the injection command signal; The waveform does not necessarily have to be the same as that of Vd. As the drive signal Vd, a signal with an appropriate waveform can be used depending on the configuration of the injector drive circuit 3, but in this embodiment, in order to simplify the explanation, the injection command signals Vh, Vs and the drive signal V are used.
d has the same waveform.

Next, the operation of the embodiment shown in FIG. 1 will be explained. When the engine rotates, the generator coils 10b and 10c induce a voltage, but at the engine starting speed, the generator coil 10
The induced voltage of b does not reach the value required to operate the microcomputer 4. Generator coil 10c at startup
Although the voltage of the injector 2 is not high, it does not require such a large voltage to flow the necessary drive current to the injector 2.
The injector drive circuit 3 is fully operational during the starting operation.

In this state, the microcomputer 4 cannot operate, so the switching signal Ve is not output. Therefore, at this time, the switching circuit 9 supplies the injection command signal Vh for hardware control outputted from the selection circuit 8 to the injector drive circuit 3 as the drive signal Vd. The injector drive circuit 3 causes a drive current to flow through the drive coil 2a of the injector 2 while the drive signal Vd is applied.

When the engine is started, the induced voltage in the generator coil 10b is established, and the microcomputer 4 is supplied with sufficient power supply voltage from the power supply circuit 11. Therefore, the microcomputer 4 outputs the switching signal Ve from the output port A2. Since this switching signal Ve is input to the switching circuit 9 through the switching signal supply control circuit 13, the switching circuit 9 supplies the injection command signal Vs for software control given from the microcomputer 4 to the injector drive circuit 3 as the drive signal Vd. The injector drive circuit 3 supplies a drive current to the drive coil 2a of the injector while the drive signal Vd is applied to inject fuel.

When the microcomputer 4 ceases to operate normally in the steady operating state of the engine, for example, when the microcomputer malfunctions and the engine runs out of control, the signal selection circuit 8 selects the steady state hard control injection. The command signal Vhn is selected and the steady-state hard control injection command signal Vhn is applied to the switching circuit 9 as the hard control injection command signal Vh. At this time, switching signal supply control circuit 1
3 prohibits the supply of the switching signal Ve to the switching circuit 9, so the switching circuit 9 supplies the injection command signal Vh for hardware control to the injector drive circuit 3 as the drive signal Vd.

In the case where a program for checking the operation of the microcomputer is incorporated into the program for operating the microcomputer, the microcomputer is configured to stop outputting the switching signal when the operation of the microcomputer becomes abnormal. In this case, the switching signal supply control circuit 13 can be omitted.

As described above, according to the fuel injection device of the present invention, even if the microcomputer does not operate normally, the signal width of the injection command signal Vh for steady-state hard control can be adjusted to a size suitable for steady-state operation. (Smaller than the width of the injection command signal for hard control at startup), it is possible to prevent the fuel from becoming too rich and to operate the engine stably.

When starting the engine when the microcomputer is out of order, the signal selection circuit 8 first selects the injection command signal for hard control during starting to start the engine, and then starts the engine. After the engine starts, the signal selection circuit 8 may select the injection command signal for hard control during steady state. Switching from the state in which the injection command signal for hard control at startup is selected to the state in which the injection command signal for hard control in steady state is selected is achieved by, for example, detecting the engine rotation speed and detecting that the rotation speed exceeds the set value. It is preferable to have the process automatically performed when the process occurs.

FIG. 2 shows an example of the configuration of the switching circuit 9 in the embodiment of FIG. 1. In the switching circuit shown in the figure, when the switching signal Ve is applied, the transistor TR1
conducts and short-circuits the hardware control injection command signal Vh. Further, at this time, the transistor TR2 is turned on and the transistor TR3 is kept in a cut-off state, so that the soft control injection command signal Vs is allowed to be input to the OR circuit OR. Therefore, when the switching signal Ve is applied, the soft control injection command signal Vs is applied to the injector drive circuit 3 as the drive signal Vd through the OR circuit OR.

When the switching signal Ve is not applied, the transistor TR2 is cut off and the transistor TR3 is turned on, so that the soft control injection command signal Vs is short-circuited, and the command signal Vs is supplied to the OR circuit OR. be prevented from being done. Also, at this time, since the transistor TR1 is in the cut-off state, the injection command signal Vh for hardware control is supplied to the injector drive circuit 3 as the drive signal Vd through the OR circuit OR.

FIG. 3 shows the signal generator 3, waveform shaping circuit 6,
This figure shows an example of the configuration of the hardware control injection command signal generation circuit 7 and signal selection circuit 8. The signal generator 1 generates pulse signals Vp1 and Vp2 having different polarities as shown in FIG. 4(A) only once per rotation in synchronization with the rotation of the engine. Here, the positional relationship between the rotor of the signal generator and the signal generator is set so that the first generated signal Vp1 reaches a threshold level at the fuel injection position of the engine.

The waveform shaping circuit 6, for example, outputs signals Vp1 and Vp1.
It consists of a flip-flop circuit that is set and reset by p2, and as shown in FIG. 4(B), the time from when the pulse signal Vp1 reaches the threshold level to when the pulse signal Vp2 reaches the threshold level A rectangular wave signal Vq with a signal width corresponding to is generated. This rectangular wave signal is inverted by the inverter IN, and the output signal Vq' (FIG. 4C) of the inverter charges the capacitor C1 through the resistor R2. This capacitor C1
When the output of the inverter IN is zero (ground level), the charge is instantly discharged through the diode D1, the output circuit of the inverter circuit IN, and the ground circuit. Capacitor C
The waveform of the terminal voltage Vc1 of 1 is as shown in FIG. 4(D), and this voltage Vc1 is input to the inverting input terminal of the comparator CP1.

Further, in order to detect the ambient temperature and the temperature of each part of the engine, a temperature sensor consisting of a positive temperature-sensitive resistance element Rth is provided, and a series circuit of this temperature-sensitive resistance element and a resistor R3 is connected to a direct current (not shown). Connected between the output terminals of the power supply,
A reference voltage Vr obtained across the resistor R3 is input to the non-inverting input terminal of the comparator CP1. The comparator CP1 outputs a rectangular wave-like injection command signal Vhi for hard control at the time of startup which is at a high level while the reference voltage Vr exceeds the terminal voltage Vc1 of the capacitor C1. The magnitude of the reference voltage Vr becomes high when the engine temperature is low and the resistance value of the temperature-sensitive resistance element is low, and becomes low when the engine temperature is high and the resistance value of the temperature-sensitive resistance element becomes high. Therefore, the hardware control injection command signal Vhi for starting when the ambient temperature or engine temperature is low has a waveform with a wide signal width as shown in Figure 4(E), and when starting when the engine temperature is high. The injection command signal Vhi for hardware control is shown in Figure 4.
As shown in (F), the signal width becomes a wider waveform than when the temperature is low.

The output Vq of the waveform shaping circuit 6 is also applied through the amplifier AM1 to both ends of a series circuit of a resistor R5 and a variable resistor VR constituting a throttle sensor. The rectangular wave signal (Fig. 4G) Va obtained at the output side of the amplifier AM1 is divided by a voltage dividing circuit consisting of a resistor R5 and a variable resistor VR, and a rectangular wave-like reference signal Vf is obtained at both ends of the variable resistor VR. It will be done. When the throttle opening is large, the resistance value of the variable resistor is large, so Fig. 4 (H)
As shown by the broken line in , the peak value of the reference signal Vf is high. Further, when the throttle opening is small, the resistance value of the variable resistor VR becomes small, so the peak value of the reference signal Vf becomes low as shown by the solid line in FIG. 4(H). The peak value of the reference signal Vf changes approximately in proportion to the throttle opening. The reference signal Vf is input to the inverting input terminal of the comparator CP2.

The output of the waveform shaping circuit 6 is also connected to the amplifier AM
2, and the output of this amplifier charges a capacitor C2 through a resistor R2. As shown in FIG. 4(H), the terminal voltage Vc2 of the capacitor C2 increases linearly with the passage of time. Square wave signal Vq
When becomes zero, the charge on capacitor C2 becomes equal to diode D.
2 and instantaneously discharges through it. The terminal voltage Vc2 of the capacitor C2 is input to the non-inverting input terminal of the comparator CP2.

The comparator CP2 outputs a rectangular-wave steady-state hard control injection command signal Vhn that is at a high level while the reference signal Vf exceeds the capacitor terminal voltage Vc2.
Output. This command signal Vhn has a waveform with a narrow signal width as shown in FIG. 4(I) when the throttle opening is small, and a wide signal width as shown in FIG. 4(J) when the throttle opening is large. It becomes a waveform.

In the embodiment shown in FIG.
, resistors R2 and R3, capacitor C1, temperature-sensitive resistance element Rth, and comparator CP1, the fuel injection time given by the hard control injection command signal for starting is controlled according to temperature information such as ambient temperature and engine temperature. A temperature correction circuit that changes information is configured. Also amplifier AM
1, AM2, resistors R4, R5 and diode D2
With variable resistor VR and comparator CP2,
A signal width correction circuit is configured to change the signal width of the injection command signal for hard control during steady state according to the throttle opening degree.

As in the embodiment shown in FIG. 3, when the information on the fuel injection time given by the injection command signal for hard control at startup is changed according to the temperature information, when the ambient temperature or the engine temperature is low, The injection time can be lengthened to make it easier to start the engine. In addition, by changing the signal width of the injection command signal for hard control during steady state according to the throttle opening, the fuel injection time can be set to a length commensurate with the throttle opening during hard control, allowing the engine to operate stably. , it is possible to fully draw out the engine's output.

In the above example, the signal width of the injection command signal for hard control during steady state is changed according to the throttle opening, but the width of the injection command signal for hard control during steady state is changed depending on other control conditions. It is also possible to vary the signal width.

The signal selection circuit 8 shown in FIG.
i or the steady state hardware control injection command signal Vhn is selected and applied to the switching circuit 9 as the hardware control injection command signal Vh. The changeover switch constituting this signal selection circuit may be a manual switch, or may be constructed from an electrically controlled switch such as a relay or a semiconductor switch.

In the embodiment shown in FIG. 3, one circuit changes the signal width of the injection command signal for hard control during startup and the injection command signal for hard control during steady state. A plurality of rectangular wave generation circuits are provided that generate rectangular wave signals with different signal widths in synchronization with the pulse signal Vp1 obtained from 3. The outputs of a plurality of rectangular wave generating circuits may be selected and output.

In the above embodiment, the microcomputer generates the switching signal, but a voltage detection circuit for detecting the power supply voltage of the microcomputer is provided, and the voltage detected by the voltage detection circuit causes the microcomputer to generate the switching signal. A switching signal may be generated by a hardware circuit when the value exceeds the minimum value required for normal operation.

[0063] Furthermore, a circuit is provided to determine whether the operation of the microcomputer is normal or abnormal by monitoring changes in the engine rotational speed, etc., and from this determination circuit, it is possible to determine whether the operation of the microcomputer is abnormal. A switching signal may be generated from time to time.

In the above embodiment, the microcomputer is driven by the output of the generator, but the present invention can be applied in exactly the same way to the case where the microcomputer is driven by the battery power source.

In the above embodiment, the fuel injection position and fuel injection time are calculated by the microcomputer, but the microcomputer calculates only 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.

[0066]

As described above, according to the present invention, the injector is driven using the injection command signal obtained by the signal generator and the electronic circuit when the microcomputer is not operating normally. Therefore, even if the microcomputer fails, the engine can be started and operated.

In particular, in the present invention, the hardware control injection command signal generation circuit generates a hardware control injection command signal for starting and a hard control injection command signal for steady state, Since these signals are used differently during steady operation, the engine can be started easily and the engine can be operated stably even in the event of a microcomputer failure.

According to the third aspect of the invention, a switching signal supply control circuit is provided which prohibits the switching signal from being applied to the switching circuit when the signal selection circuit selects the hard control signal during steady state. By providing this, it is possible to prevent the engine from running out of control due to an erroneous signal being supplied from a failed microcomputer while the engine is being operated in a steady state using the injection command signal for hardware control.

Furthermore, according to the invention set forth in claim 4, since a temperature correction circuit is provided that changes the information on the fuel injection time given by the injection command signal for hard control at the time of starting according to the temperature information, the ambient temperature The fuel injection time can be adjusted depending on the temperature of the engine and the temperature of the engine to ensure engine startup.

Further, according to the invention as set forth in claim 5, the information on the fuel injection time given by the injection command signal for hard control during steady state can be adjusted to an optimal value according to the opening degree of the throttle valve of the engine. It is possible to operate the engine stably and fully extract its output even when the microcomputer is not used.

[Brief explanation of the drawing]

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

FIG. 2 is a connection diagram showing a specific example of a switching circuit used in an embodiment of the present invention.

FIG. 3 is a connection diagram showing a specific example of the configuration of main parts of the device of the present invention.

FIG. 4 is a waveform diagram showing signal waveforms at various parts in FIG. 3;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1...Signal generator, 2...Injector, 3...Injector drive circuit, 4...Microcomputer, 6...Waveform shaping circuit, 7...Injection command signal generation circuit for hardware control, 8...Signal selection circuit, 9...Switching circuit, 10 ... Generator, 11, 12...
Power supply circuit, 13... Switching signal supply control circuit, 100... Hard injection command signal generation circuit, 101... Injector drive current supply control circuit.

Claims (6)

[Claims] 1. An injector, a microcomputer that calculates a fuel injection time based on various detected control conditions and outputs an injection command signal for software control including information on the calculated fuel injection time; It is installed separately from the computer, and when the engine is started, it outputs an injection command signal for hard control including information on the fuel injection time suitable for starting, and when the engine is running normally, it outputs a fuel injection command signal that is suitable for steady engine operation. A hardware control injection command signal generation circuit outputs an injection command signal for hard control during steady state including time information, and when the microcomputer is in a normal operating state, the injection command signal is given by the software control injection command signal. A driving current is passed through the injector during the fuel injection time, and when the microcomputer is not operating normally, the fuel injection time is given by a hardware control injection command signal output from the hardware control injection command signal generation circuit. and an injector drive current supply control circuit that causes a drive current to flow through the injector during the period of time. 2. The injector drive current supply control circuit is an injector drive circuit that, when a drive signal including information on a fuel injection time is input, causes a drive current to flow through the injector for a fuel injection time given by the drive signal. and a switching signal generating means for generating a switching signal when the microcomputer is operating normally, and a hardware control unit for generating a switching signal obtained from the hardware control injection command signal generation circuit when the switching signal is not generated. A switching circuit that supplies the injection command signal as a drive signal to the injector drive circuit, and supplies the injection command signal for software control to the injector drive circuit as a drive signal when a switching signal is generated. Claim 1
A fuel injection device for an internal combustion engine according to. 3. When the hardware control injection command signal generation circuit is generating the hardware control injection command signal for starting, the switching signal is allowed to be applied to the switching circuit, and the hardware control Further comprising a switching signal supply control circuit that prohibits the switching signal from being applied to the switching circuit when the control injection command signal generation circuit is generating the hard control injection command signal for steady state. The fuel injection device for an internal combustion engine according to claim 2, characterized in that: 4. A temperature sensor that detects temperature information necessary for determining fuel injection time; and a hardware control injection command obtained from the hardware control injection command signal generation circuit in accordance with the information obtained from the temperature sensor. 4. The fuel injection device for an internal combustion engine according to claim 1, further comprising a temperature correction circuit that changes information about fuel injection time included in the signal. 5. A throttle sensor that detects a throttle opening of an internal combustion engine, and a signal that changes fuel injection time information included in the hardware control injection command signal according to throttle opening information obtained from the throttle sensor. The fuel injection device for an internal combustion engine according to any one of claims 1 to 5, further comprising a correction circuit. 6. The hardware control injection command signal generation circuit and the microcomputer are driven by separate power supplies.
The fuel injection device for an internal combustion engine according to.