JP3028708B2 - Injector drive for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injector driving device for driving an injector 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 optimum state, it is important to properly control the air-fuel ratio in accordance with the temperature, rotation speed, etc. of each part of the engine. When fuel is supplied to the engine by the injector, the amount of fuel injection is determined by the time during which fuel is injected from the injector (fuel injection time) and the pressure of fuel (fuel pressure) applied to the injector. Also, since the air-fuel ratio is affected by temperature and atmospheric pressure, it is necessary to accurately control the fuel injection time according to control conditions such as atmospheric pressure and the temperature of each part to control the air-fuel ratio accurately. It is.

[0003] Therefore, recently, a fuel injection device for an internal combustion engine, which controls a fuel injection time by using a microcomputer, has been used. The microcomputer calculates the fuel injection position (rotation angle position at which fuel injection is started) and the fuel injection time by using information such as atmospheric pressure and temperature given from the sensor and the output of the signal generator as inputs. At the calculated fuel injection position, an injection command signal including information on the calculated fuel injection time is given to the injector drive circuit. The injection command signal rises at the fuel injection position, for example, and consists of a rectangular wave signal having a signal width equal to the fuel injection time. The injector drive circuit supplies a drive current to the injector while the injection command signal is given. The injector opens its valve and injects fuel while the drive current is applied.

In this type of fuel injection device, fuel is not injected when the voltage of the power supply of the microcomputer is reduced and the microcomputer is not operated. For example, when the engine is started, the power supply voltage of the microcomputer is not increased. If it is low, the engine cannot be started.

Further, in order to enable the microcomputer to control the injector in an internal combustion engine which is started by manual start or kick start without mounting a battery, the microcomputer is used as a power source by a generator driven by the internal combustion engine. Need to work,
In this case, the microcomputer cannot be operated normally until the output voltage of the generator is established at the time of starting the engine, so that starting the engine becomes difficult.

Further, even when the power supply of the microcomputer is secured, if the CPU malfunctions or if it becomes impossible to determine the cylinder of the multi-cylinder internal combustion engine, the control by the microcomputer should be performed properly. Can not be done.

In order to solve the above-mentioned problems, when the microcomputer is in a normal operating state,
An injector control device has been proposed in which an injector is controlled by a microcomputer, and when the microcomputer does not operate normally, the injector is controlled by a hardware circuit.

As shown in FIG. 8, the control device according to the present invention calculates a fuel injection time according to various control conditions by a microcomputer and outputs a signal having a time width corresponding to the calculated fuel injection time. Injection command signal for software control Vj
Injection command signal generator a for software control generated as'
A hard control injection command signal generating unit b that generates a signal having a time width corresponding to a predetermined fuel injection time as a hard control injection command signal Vj using a hardware circuit;
When the microcomputer is operating normally, the drive current is supplied to the injector while the injection command signal for software control is being generated. When the microcomputer is not operating properly, the injection command signal for hardware control is generated in an emergency. And an injector driving circuit c for supplying a driving current to the injector during the operation.

The hard control injection command signal generator b detects the rotation of the internal combustion engine and, as shown in FIG. 9, rotates when the rotation speed of the engine reaches the set value N 1. A rotation detection circuit d for outputting a detection signal Vd, and a starting injection command signal generating circuit for outputting a rectangular wave signal having a signal width corresponding to an injection time tjs suitable for starting the internal combustion engine as a starting injection command signal Vj1. e, a steady-state injection command signal generation circuit f that outputs a square-wave signal having a signal width corresponding to the injection time tjn (<tjs) suitable for steady-state operation as the steady-state injection command signal Vj2, and a rotation detection signal Vd. Is not given, the start-time injection command signal Vj1 is selected and output as the hard control injection command signal Vj. When the rotation detection signal is given, the steady-state injection command signal Vj2 is output.
And a signal selection circuit g for selecting and outputting as a hardware control injection command signal Vj.

The injector driving circuit c includes a switching circuit h
And a switch circuit k including a transistor Tr. The microcomputer constituting the soft control injection command signal generator a generates a high-level switching signal Ve when operating normally, and stops generating the switching signal Ve when it stops operating normally. . Switching signal V
e is given to the control terminal of the switching circuit h. The switching circuit h supplies a trigger signal to the base of the transistor Tr included in the switch circuit k during the period in which the soft control injection command signal Vj 'is generated when the switching signal Ve is supplied, and supplies the switching signal Ve. Is stopped, a trigger signal is given to the transistor Tr while the hard control injection command signal Vj is being generated. The transistor Tr conducts while the trigger signal is being supplied from the switching circuit h, and allows a drive current to flow from a power supply circuit (not shown) to the drive coil Li of the injector. The injector opens the valve only while the drive current is being supplied, and injects fuel into the fuel injection space of the engine (usually in the throttle body).

When the injector is driven by the above-described injector driving device, the temporal change of the fuel injection time tj is as shown in FIG. That is, when the engine is started, the injection time tj becomes equal to the signal width tjs of the start-time injection command signal Vj1, and the fuel is supplied to the engine in an amount larger than that during normal operation. After the start, at time t1, when the engine speed reaches N1 and the rotation detection signal Vd is generated, the injection time tj becomes equal to the signal width tjn of the steady-state injection command signal Vj2.

[0012]

When fuel is injected from the injector into the throttle body when the engine is started,
The injected fuel is transported to the cylinder side while forming a liquid film on the wall surface of the throttle body. Initially, a large amount of fuel is taken into the liquid film, so only a small part of the injected fuel is supplied to the cylinder.However, as the fuel that has formed the liquid film evaporates over time, the cylinder The amount of fuel supplied inside increases exponentially. Therefore, it can be seen that the fuel transport system at the start of the engine is a first-order lag system.

In particular, in a two-stroke engine, the fuel supplied to the throttle body enters the cylinder after passing through the crank chamber and the scavenging port, so that the amount of fuel used to form a liquid film when the engine is started is reduced. As a result, the amount of fuel supplied to the cylinder in the initial stage of starting the engine is reduced.

Now, in a two-cycle engine, as shown in FIG. 11, an injection command signal V generated by a hardware circuit is generated.
Assuming that the signal width of j is equal to the steady-state injection time tjn and the engine start operation is performed with the fuel injection time at each injection timing being constant (= tjn), the amount of fuel supplied to the cylinder is equal to the time tj. Change as shown in FIG. That is, during the period from time 0 to ta, a large amount of fuel is taken for the formation of the liquid film, so that the fuel supply amount Q to the cylinder is very small. When the fuel vaporization is promoted after the time ta, the fuel supply amount to the cylinder increases exponentially, and when the time tb is reached, the fuel supply amount reaches the saturation value Qs.

As described above, when the engine is started with the injection time fixed at the steady-state value, the mixture becomes lean from time 0 to tb, so that the engine can be started. Or the rotation of the engine cannot be stably maintained. At the start of the engine, the injector is driven by a hardware circuit so that the start of the engine can be performed without any trouble and the engine can be operated stably. It is necessary to compensate for the delay in fuel supply until The characteristic of the injection time tj required in this case (startup increase characteristic) is as shown by a curve A in FIG.

In a four-cycle engine in which fuel does not pass through the crank chamber, the characteristic of the injection time tj required at the time of starting the engine is as shown by a curve B in FIG. However, in the injector drive device already proposed, as shown in FIG. 10, the injection time tjs at the start and the injection time tjn at the time of the steady operation were constant.
In this case, it was not possible to perform the starting amount increase control having the characteristics shown in FIG.

For example, when the start-up fuel increase control as shown in FIG. 10 is performed in a two-cycle engine, as shown in FIG. 14, only the portion A shown in FIG. The mixture becomes thicker (richer)
Therefore, there arises a problem that the rise of the rotation speed becomes slow and the rise of the rotation becomes unstable, and HC in the exhaust gas increases.

During the period from time t1 to tb, the air-fuel mixture supplied to the cylinder becomes lean (lean) only in the portion B shown in the figure. Therefore, even when the throttle opening is in the idle state, the relationship with the idle air-fuel ratio is not significant. As a result, there arises a problem that the engine speed increases.

An object of the present invention is to provide an injector drive device for an internal combustion engine, which can obtain a starting quantity increase characteristic required by an engine by a hardware circuit.

[0020]

According to the present invention, a microcomputer calculates a fuel injection time according to various control conditions and generates a soft control injection command signal having a time width corresponding to the calculated fuel injection time. A soft control injection command signal generating section, a hard control injection command signal generating section for generating a hardware control injection command signal having a time width corresponding to the fuel injection time by a hardware circuit, and a microcomputer operating normally. When the microcomputer is not operating normally, the drive current is supplied to the injector while the soft control injection command signal is being generated. The present invention relates to an injector drive device for an internal combustion engine including an injector drive circuit for supplying a current.

According to the present invention, the hardware control injection command signal generating section includes a timing signal generating means for generating a timing signal at a fuel injection position of the internal combustion engine;
Signal width determination comprising a resistor circuit having a combined resistance value of R and a semiconductor active element connected to a part of the resistance circuit and reducing the combined resistance value R of the resistance circuit when the resistance circuit becomes conductive. And a time constant R of the signal width determination circuit.
A rectangular wave signal generating circuit for generating a rectangular wave signal having a signal width determined by C as a hard control injection command signal;
A semiconductor active element control circuit for controlling the semiconductor active element so as to gradually reduce the internal impedance of the semiconductor active element after the internal combustion engine is started.

The resistor circuit includes, for example, a steady-state signal width determining resistor for determining a signal width during steady-state operation of the internal combustion engine, and a starting-time increasing amount connected in series to the steady-state signal width determining resistor. And a determining resistor. In this case, the semiconductor active element is connected in parallel to the starting increase width determining resistor.

The resistor circuit may further include a first resistor and a second resistor connected in parallel to the first resistor through a semiconductor active device.
, And can be constituted by the above resistors.

It is desirable that the resistance circuit has a temperature-sensitive resistance element for temperature compensation which reduces the combined resistance value when the ambient temperature rises.

In the above configuration, the steady-state signal width determining resistor, the starting increase amount determining resistor, and the first and second resistors may each be composed of a single resistance element. It may consist of.

[0026]

As described above, a semiconductor active element is connected to a part of the resistor circuit for determining the signal width of the rectangular wave signal generating circuit, and when the semiconductor active element is turned on, the combined resistance value of the resistor circuit is reduced. In addition, when the internal combustion engine is started, a semiconductor active element control circuit for controlling the semiconductor active element so as to gradually reduce the internal impedance of the semiconductor active element from the cut-off state is provided. After the engine is started, the injection time can be gradually shortened to finally converge to the value at the time of steady operation. Therefore, the output of the hard control injection command signal generating section can obtain the starting increase characteristic close to the ideal characteristic as shown in FIG. 12, and the engine can be started even when the microcomputer does not function properly. The engine performance can be improved, and the rotation of the engine at low speed can be stably maintained.

[0027]

FIG. 1 shows an overall configuration of an embodiment of the present invention. In FIG. 1, reference numeral 10 denotes a soft control injection command signal generator, 11 denotes a hard control injection command signal generator, 1
Reference numeral 2 denotes an injector drive circuit for supplying a drive current to the injector 13, and reference numeral 14 denotes a power supply circuit that outputs a constant DC voltage using a power generation coil 15 provided in a magnet generator mounted on the internal combustion engine as a power supply.

The software control injection command signal generating unit 10
The microcomputer 10A is driven by the output of the power supply circuit 14, and is provided with predetermined software for operating the microcomputer. The microcomputer 10A outputs an output of a throttle sensor for detecting an opening degree of a throttle valve, and a temperature for detecting an intake air temperature. A soft control injection command signal Vj 'for giving a fuel injection time is output by inputting the outputs of various sensors such as a sensor and an atmospheric pressure sensor for detecting the atmospheric pressure.
The soft control injection command signal generating section 10 may be the same as that used in a conventional fuel injection device for an internal combustion engine in which injection time is controlled by a microcomputer.

The hardware control injection command signal generating unit 11
A signal generator 11A for generating a timing signal Vt for controlling the injection time at a predetermined rotation angle position of the internal combustion engine, comprising a signal generator 1 driven by the internal combustion engine; A rectangular wave signal generating circuit 11B generates a rectangular wave signal having a signal width determined by the time constant of the signal width determining circuit as the hard control injection command signal Vj every time Vt is given. A specific configuration example of the hardware control injection command signal generation unit will be described later.

The output of the signal generator 1 is also supplied to a microcomputer 10A through a waveform shaping circuit (not shown). The microcomputer 10A includes the signal generator 1
The fuel injection position and the fuel injection time at each rotation speed are calculated by obtaining the rotation angle information and the speed information of the engine from the output of (1).

The injector drive circuit 12 supplies a drive current to the injector 13 during the generation of the soft control injection command signal Vj 'when the microcomputer is in a state where it can operate normally, and the microcomputer operates normally. When it is not in the state, the switching circuit 12A and the switching circuit 1A provide a driving current to the injector 13 while the hardware control injection command signal Vj is being generated.
2B.

The program for operating the microcomputer 10A includes a check program for checking whether the microcomputer is operating normally by a known method, and the microcomputer operates normally. , A high-level switching signal Ve is generated, and when a malfunction occurs, the generation of the switching signal Ve is stopped. This switching signal Ve
Is supplied to the control terminal of the switching circuit 12A. The switching circuit 12A applies a trigger signal to the control terminal of the switch circuit 12B during the period when the microcomputer 10A is generating the soft control injection command signal Vj 'when the switching signal Ve is given, and the operation of the microcomputer Is not performed normally and the supply of the switching signal Ve is stopped, a trigger signal is given to the control terminal of the switch circuit 12B during the period when the rectangular wave signal generation circuit 11B is generating the hard control injection command signal Vj. Switch circuit 12B
Is turned on only during the period when the trigger signal is given from the switching circuit 12A, and the drive current flows from the power supply circuit 14 to the drive coil 13a of the injector 13. Injector 13
Opens the valve and injects fuel into the fuel injection space of the engine only while the drive current is being applied.

In the apparatus shown in FIG. 1, when the microcomputer 10A operates normally, a drive current is supplied to the injector 13 while the microcomputer generates the soft control injection command signal Vj '.
The fuel injection time is controlled by the microcomputer 10A.

When the microcomputer 10A does not operate normally because the power supply is not established when the engine is started, or when the microcomputer 10A does not operate normally for some reason during the operation of the engine, the microcomputer 10A In order to stop the output of the switching signal Ve, the switching circuit 12A supplies a trigger signal to the switch circuit 12B while the hard control injection command signal generating section 11 is generating the injection command signal Vj. Therefore, in an emergency when the microcomputer does not operate normally, the fuel injection time is controlled by the hard control injection command signal generator 11.

FIG. 2 shows a specific example of the configuration of the injection command signal generator 11 for hardware control used in the embodiment of the present invention. In FIG.
2 is a signal generator. The rotor 101 is provided with a reductor 101a on the outer periphery of a rotating body made of iron, and is attached to a rotating shaft of the engine. As a rotating body constituting the rotor, a flywheel of a flywheel magnet rotor attached to an engine can be used.

The signal generator 102 has a known structure including an iron core having a magnetic pole portion facing the rotor 101, a signal coil 102a wound around the iron core, and a permanent magnet magnetically coupled to the iron core. , The reactor 101a is the signal emitting 1
02 starts to oppose the magnetic pole portion of the iron core 02 and ends when the opposition ends.
2a, pulse signals Vs1 and Vs2 are generated.

The reluctor provided on the rotor 101 only needs to generate a magnetic flux change in signal emission at one end and the other end in the circumferential direction, and may be a concave portion provided on the outer peripheral portion of the rotating body.

The signal generator 1 does not necessarily need to use the above-mentioned signal emission, but detects a change in magnetic flux generated by a reluctor using a semiconductor magnetic detecting element such as a Hall IC. It may be something.

In this embodiment, of the pulse signals Vs1 and Vs2 obtained from the signal generator 1, the positive signal Vs1 is shaped into a pulse by the waveform shaping circuit 16 and used as the timing signal Vt. The mounting angle of the rotor 101 is set so that the timing signal Vt is generated at a position (fuel injection position) suitable for starting fuel injection.

The above-mentioned timing signal Vs1 is input to the trigger terminal TRG of the monostable multivibrator 5 composed of an IC. A signal width determining circuit 6 is connected between an external capacitor / resistor connection terminal Th of the monostable multivibrator 5 and a ground terminal GND, and a rectangular wave signal generating circuit is formed by the monostable multivibrator 5 and the signal width determining circuit 6. 11B is configured. This square wave signal generation circuit
Each time the timing signal Vt is supplied, the signal width determination circuit 6
Is generated as the hard control injection command signal Vj having a signal width tj determined by the time constant of The signal width tj is the fuel injection time.

The signal width determining circuit 6 is connected between the terminal Th of the monostable multivibrator 5 and GND, and between the terminal Th and a terminal to which the voltage E is applied from the power supply circuit. Resistance circuits (6b to 6d);
And a PNP transistor 6e as a semiconductor active element connected to a part of the resistance circuit.

The resistor circuit includes a steady-state signal width determining resistor 6 having one end connected to the terminal Th of the monostable multivibrator.
b, a starting signal width determining resistor 6c connected between the other end of the resistor 6b and a power terminal to which the power voltage E is supplied;
A temperature-compensating temperature-sensitive resistance element 6d having a negative temperature coefficient is connected in parallel to both ends of the resistor 6c. The transistor 6e has its collector-emitter terminal connected in parallel to both ends of the resistor 6c. .

A resistor 17 is connected to the base of the transistor 6e.
a is connected to one end, and a capacitor 17b is connected between the other end of the resistor 17a and the ground. A switch circuit 17c is connected between the non-grounded terminal of the capacitor 17b and the collector of the transistor 6e, and a resistor 17d is connected to both ends of the capacitor 17b. Also provided is a rotation detection circuit 17e which detects the number of revolutions of the engine from the generation cycle of the timing signal Vt obtained from the waveform shaping circuit 16 and outputs a rotation detection signal Vn when the number of revolutions reaches a set value. The rotation detection signal Vn obtained from the rotation detection circuit 17e is supplied to the control terminal of the switch circuit 17c. The switch circuit 17c is made up of a semiconductor switch element or a relay, and its control terminal has a rotation detection signal V.
When n is not supplied, the conduction state is maintained, and when the rotation detection circuit 17e generates the rotation detection signal Vn, the state is cut off.

In this embodiment, the resistors 17a and 17d, the capacitor 17b, the switch circuit 17c, and the rotation detecting circuit 1
The semiconductor active element control circuit 17 for controlling the semiconductor active element (transistor 6e) is constituted by 7e.

The injection command signal generator 1 for hardware control shown in FIG.
The operation of No. 1 is as follows.

Assuming that the starting operation of the engine is started at time 0, the rotational speed N of the engine changes as time t elapses, for example, as shown in FIG. 3A. Rotation detection circuit 1
7e outputs a rotation detection signal Vn when the rotation speed N reaches the set value Na at time ta.

In a state where the rotation detection circuit 17e is not generating the rotation detection signal Vn, the switch circuit 17c is in a conductive state. Therefore, when a start operation of the engine is performed and a power supply voltage is applied to the power supply terminal E, The capacitor 17b is charged instantaneously. When the switch circuit 17c is closed, the transistor 6e is kept in the cut-off state.

When the transistor 6e is in the cutoff state, the combined resistance value R of the resistance circuit of the signal width determination circuit 6 is the sum of the parallel combined resistance value of the resistor 6c and the temperature-sensitive resistance element 6d and the resistance value of the resistor 6b. The signal width of the hard control injection command signal Vj is determined by the product of the combined resistance value R and the capacitance C of the capacitor 6a. The resistance value of each resistor and the capacitance of the capacitor 6a are set so that the signal width tj of the injection command signal Vj is equal to the desired injection time tja of the ideal increase characteristic of FIG.

When the rotation detection signal Vn is generated at time ta, the switch circuit 17c is turned off. When the switch circuit 17c is cut off, the electric charge of the capacitor 17b is discharged through the resistor 17d, and the voltage Vc across the capacitor 17b decreases as shown in FIG. As the voltage at both ends of the capacitor decreases, the base current I of the transistor 6e as shown in FIG.
b increases, and as shown in FIG. 3E, the resistance Ztr between the collector and the emitter of the transistor 6e decreases. Therefore, as shown in FIG. 3F, the combined resistance value Zp of the collector-emitter circuit of the transistor 6e and the parallel circuit of the resistor 6c and the temperature-sensitive resistor 6d gradually decreases with time. . Therefore, the time constant RC of the signal width determination circuit 6 decreases as time elapses, and the signal width (fuel injection time) of the hard control injection command signal Vj
tj gradually decreases from time ta as shown in FIG. 3 (G). In this embodiment, the transistor 6e is finally turned on, and the resistor 6c and the temperature-sensitive resistor 6d are finally turned on.
Is substantially short-circuited, the injection command signal V
The signal width of j is determined by the resistance value of the resistor 6b and the capacitance of the capacitor C. In this state, the resistance value of the resistor 6b is set so that the signal width of the injection command signal Vj is equal to the injection time tjn in the steady operation. Time t
a so that the decreasing rate of the signal width of the subsequent injection command signal is substantially equal to the decreasing rate of the injection time of the increasing characteristic in FIG.
The discharge time constant of the capacitor 17b is set.

When fuel is supplied to the internal combustion engine by the injector, the air-fuel ratio is determined by the mass A of air taken into the intake pipe.
And the mass (F / A) of the injected fuel (F / A). Therefore, even if the volume of air taken into the intake pipe is the same, if the temperature of the air changes and its density changes, the air-fuel ratio changes.

That is, since the mass of air decreases as the air temperature increases, when the volume of intake air is constant, or when the fuel injection time required to obtain an air-fuel ratio is determined by the intake air temperature, It becomes shorter with the rise. Therefore, if the injection time is constant regardless of the intake air temperature, the fuel becomes rich when the intake air temperature is high, and the fuel becomes lean when the intake air temperature is low, which may hinder the operation of the engine. There is. Therefore, in order to operate the engine normally while keeping the air-fuel ratio in an appropriate range, it is necessary to shorten the fuel injection time as the intake air temperature rises.

When the temperature-sensitive resistance element 6d having a negative temperature coefficient is provided as in the above-described embodiment, the time width of the hard control injection command signal at the time of starting is reduced as the temperature rises. Therefore, it is possible to prevent the fuel supplied at the time of starting from becoming rich when the air temperature is high or lean when the air temperature is low.

In the above embodiment, the transistor 6e (semiconductor active element) is controlled so as to be finally turned on. However, in the steady operation state, the transistor 6e is in the active region and a predetermined internal resistance is set. In such a case, the transistor 6e may be controlled. In such a configuration, steady operation is performed by the sum of the resistance value of the resistor 6b and the sum of the combined resistance value of the parallel circuit of the resistor 6e, the temperature-sensitive resistance element 6d, and the transistor 6e, and the capacitance of the capacitor 6a. The fuel injection time is also determined.

FIG. 4 shows the configuration of a hard control injection command signal generating section used in another embodiment of the present invention. In this embodiment, a resistor 17a having one end connected to the base of the transistor 6e and a resistor 17a are provided. The collector of an NPN transistor 17f whose emitter is grounded is connected to the end, and the base of the transistor 17f is connected to a capacitor 17b via a resistor 17g.
Is connected to the non-ground side terminal of The output of a power generating coil 17h provided in a magnet generator mounted on the internal combustion engine is applied to both ends of the capacitor 17b through a diode 17i and a resistor 17j. In this example, the resistors 17a, 17g and 17j, the transistor 17f,
The capacitor 17b, the diode 17i, and the power generation coil 1
7h constitute a semiconductor active element control circuit 17. Other points are the same as those in the example shown in FIG.

The operation of the hardware control injection command signal generator shown in FIG. 4 will be described with reference to FIGS. 5 (A) to 5 (G).

In this example, after starting the engine at time 0,
It is assumed that the engine is stopped at time tb and restarted at time tc. When the engine is started at time 0, the rotational speed N of the engine increases as shown in FIG. When the engine rotates, the output voltage of the power generation coil 17h increases, so that the voltage Vc (FIG. 5B) across the capacitor 17b charged by the output of the power generation coil 17h through the diode 17i and the resistor 17j increases. When the engine speed reaches the set value at time ta and the voltage Vc across the capacitor 17b reaches the set value, as shown in FIG.
The base current Ib1 starts flowing through the transistor 17f. As the internal resistance between the collector and the emitter of the transistor 17f decreases with an increase in the base current Ib1,
As shown in (D), the base current I of the transistor 6e
As the base current Ib2 increases, the internal resistance Ztr1 between the collector and the emitter of the transistor 6e decreases as shown in FIG. 5 (E). for that reason,
As shown in FIG. 5F, the resistor 6c and the temperature-sensitive resistor 6
The combined resistance value Zp of the parallel circuit of d and the collector-emitter circuit of the transistor 6e also decreases. Therefore, FIG.
As shown in (G), the time constant of the signal width determination circuit 6 decreases, and the signal width tj of the injection command signal Vj decreases. In this embodiment, since the transistor 6e is finally turned on, the signal width tj is equal to the steady-state injection time tjn.
Converges to

When the engine is restarted at time tc, since the charge of the capacitor 17b remains, the transistors 17f and 6e enter the active region from the beginning and the internal resistance between the collector and the emitter of the transistor 17f shows a low value. Therefore, as shown in FIG. 5 (G), when the engine is restarted, the signal width tj of the injection command signal Vj becomes narrow, and the amount of fuel supplied at the time of starting is reduced. With this configuration, the amount of fuel increase can be reduced at the time of restarting the engine where it is almost unnecessary to increase the amount of fuel. Can be prevented from becoming difficult.

If it takes a long time until the next start of the engine after stopping the engine, the engine cools down during that time, so it is necessary to increase the amount of increase at the start. In the example shown in FIG. 4, the charge of the capacitor 17b is discharged slowly through the resistor 17g and between the base and the emitter of the transistor 17f, as indicated by the dashed arrow in the figure. The state of the semiconductor active element control circuit 17 can be returned to the initial state,
The value t when the engine is cold with the increase in the injection amount at the start
You can go back to ja.

In the example shown in FIG. 4, when a diode whose anode is directed toward the capacitor 17b is inserted between the base of the transistor 17f and the non-ground terminal of the capacitor 17b, the transistor is reduced by the forward voltage drop of the diode. The trigger level of the transistor 1
Since the time at which 7f starts conducting can be delayed, the time during which the injection time remains at tia at the time of starting can be extended.

In the example shown in FIG. 2, the semiconductor active element (transistor 6e) is connected in parallel with the resistor 6c.
As shown in FIG. 6, a resistor 6c may be connected to both ends of a temperature-sensitive resistance element 6d through a collector-emitter circuit of a transistor 6e. In this example, the temperature-sensitive resistance element 6d and the resistance 6c are used as first and second resistances which determine the injection time at the time of starting and at the time of steady state. Further, the resistor 6b provided in the example of FIG. 2 is omitted. Other points are the same as in the example of FIG.

In the example shown in FIG. 6, while the transistor 6e is turned off when the engine is started, the signal width of the injection command signal Vj is determined by the resistance value of the temperature-sensitive resistance element 6d and the capacitance of the capacitor 6a. . When the rotation detection signal Vn is output and the switch 17c is opened and the internal resistance of the transistor 6e starts to decrease, the series combination value of the resistance 6c and the collector-emitter resistance of the transistor 6e and the resistance value of the temperature-sensitive resistance element 6d are calculated. The signal width of the injection command signal Vj is determined by the parallel combined value and the capacitance of the capacitor 6a, and the injection time tj becomes shorter. When the transistor 6e is completely turned on, the signal width of the injection command signal Vj is determined by the parallel combined value of the resistance 6c and the resistance value of the temperature-sensitive resistance element 6d and the capacitance of the capacitor 6a. The injection time tj converges to the steady state value tjn.

In each of the above embodiments, a transistor is used as a semiconductor active element. However, another semiconductor active element, for example, a field effect transistor can be used. For example, as shown in FIG.
e and 17f to P-channel junction F
ET6e 'and N-channel MOSFET 17f'. NPN transistor 17 of FIG.
If an attempt is made to discharge the charge of the capacitor 17b through the gate circuit of the FET using an N-channel MOSFET instead of f, it takes a very long time to discharge.
In the example shown in FIG. 7, a resistor 17k is provided to
7b is shortened.

In each of the above embodiments, a monostable multivibrator is used as the rectangular wave signal generating circuit. However, a rectangular wave signal generating circuit having another configuration can be used.

In the examples shown in FIGS. 2, 7 and 8, a monostable multivibrator IC is used. However, a monostable multivibrator constructed by combining two flip-flop circuits and an integrating circuit is used. You can also.

In the embodiments of FIGS. 1, 4 and 7, a temperature-sensitive resistor having a negative temperature coefficient is connected to both ends of the resistor 6b, or the resistor 6b is replaced by a temperature-sensitive resistor having a negative temperature coefficient. By replacing the temperature, the temperature of the injection time during the steady operation can be compensated.

[0066]

As described above, according to the present invention, a semiconductor active element is connected to a part of a resistor circuit for determining the signal width of a rectangular wave signal generating circuit, and the resistance is set when the semiconductor active element is turned on. Since the combined resistance value of the circuit is reduced and a semiconductor active element control circuit for controlling the internal impedance of the semiconductor active element from the cut-off state to the internal impedance gradually after the internal combustion engine is started is provided. The injection time at the start of the start can be made longer than the injection time at the time of the steady operation, and after the engine is started, the injection time can be gradually shortened to finally converge to the value at the time of the steady operation. Therefore, the output of the hard control injection command signal generating section can provide an increase in starting characteristic close to the ideal characteristic. Even when the microcomputer does not function normally, the starting performance of the engine can be improved, and the low speed of the engine can be improved. There is an advantage that the rotation at the time can be stably maintained.

[Brief description of the drawings]

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

FIG. 2 is a circuit diagram showing a specific configuration example of a hardware control injection command signal generation unit used in the apparatus of FIG. 1;

FIG. 3 is a waveform chart showing signal waveforms at various parts in FIG. 2;

FIG. 4 is a circuit diagram showing another example of the configuration of the hardware control injection command signal generator used in the present invention.

FIG. 5 is a waveform chart showing signal waveforms at various parts in FIG. 4;

FIG. 6 is a circuit diagram showing another example of the configuration of the hardware control injection command signal generator used in the present invention.

FIG. 7 is a circuit diagram showing another example of the configuration of the hard control injection command signal generator used in the present invention.

FIG. 8 is a block diagram showing a configuration of a conventional injector driving device.

FIG. 9 is a diagram showing a change over time of the rotation speed at the time of starting the engine.

FIG. 10 is a diagram showing a starting amount increase characteristic obtained by a conventional injector driving device.

FIG. 11 is a diagram showing a state in which the injection time is fixed to a normal size.

FIG. 12 is a diagram showing a temporal change of a fuel supply amount when an injection time is fixed as shown in FIG. 11;

FIG. 13 is a diagram showing an ideal start-up increasing characteristic required by the engine.

FIG. 14 is a diagram for explaining a problem of a conventional injector driving device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Signal generator 5 Monostable multivibrator 6 Signal width determination circuit 6a Capacitor 6b, 6c Resistance 6d Temperature-sensitive resistance element 6e Transistor (semiconductor active element) 10 Soft control injection command signal generator 11 Hard control injection command signal generator 17 Semiconductor active element control circuit

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F02D 41/20 325 F02D 41/06 330

Claims (4)

(57) [Claims] 1. A soft control injection command signal generating means for calculating a fuel injection time according to various control conditions by a microcomputer and generating a soft control injection command signal having a time width corresponding to the calculated fuel injection time. A hard control injection command signal generating section for generating a hard control injection command signal having a time width corresponding to the fuel injection time by a hardware circuit, and the soft control injection when the microcomputer is operating normally. An injector drive for supplying a drive current to the injector while the command signal is being generated, and supplying a drive current to the injector while the hard control injection command signal is being generated when the microcomputer is not operating normally. And an injector drive device for an internal combustion engine, comprising: A timing signal generating means for generating a timing signal at a fuel injection position of the internal combustion engine; a capacitor having a capacitance of C; a resistance circuit having a combined resistance value of R; A rectangular wave signal having a signal width determined by a time constant RC of the signal width determining circuit, the signal width determining circuit including a semiconductor active element for reducing the combined resistance value R of the resistor circuit when A rectangular wave signal generation circuit that generates the hard control injection command signal, and a semiconductor active element control circuit that controls the semiconductor active element to gradually decrease its internal impedance from a cutoff state after the internal combustion engine is started. An injector driving device for an internal combustion engine, comprising: 2. The resistance circuit according to claim 1, further comprising: a resistor for determining a signal width at a steady state for determining a signal width during a steady operation of the internal combustion engine; The injector drive device for an internal combustion engine according to claim 1, further comprising a width determining resistor, wherein the semiconductor active element is connected in parallel to the start-time increasing width determining resistor. 3. The resistance circuit according to claim 1, wherein the resistance circuit has a first resistance and a second resistance connected in parallel to the first resistance through the semiconductor active element.
An injector drive device for an internal combustion engine according to claim 1. 4. The resistance circuit according to claim 1, wherein said resistance circuit includes a temperature-sensitive resistance element for temperature compensation for decreasing said combined resistance value when an ambient temperature rises.
The injector drive device for an internal combustion engine according to any one of the above.