JP3134598B2 - Method and apparatus for controlling injector 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 control method for controlling an injector for supplying fuel to an internal combustion engine, and a control device used for implementing the method.

[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 the fuel 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.

[0007] In order to solve the above problems, there has been proposed an injector control device that controls the injector by a hardware circuit when the microcomputer does not operate normally. The control device according to the prior art is configured to calculate a fuel injection time according to various control conditions by a microcomputer and to generate a steady-state injection command signal having a time width corresponding to the calculated fuel injection time. A command signal generator, an emergency injection command signal generator for generating an emergency injection command signal having a time width corresponding to the fuel injection time by a hardware circuit, and a steady state when the microcomputer is operating normally. Injector drive circuit that supplies drive current to the injector while the injection command signal is being generated, and in which the microcomputer is not operating normally during emergency when the emergency injection command signal is generated And

[0008]

In the emergency injection command signal generator provided in the injector control device proposed previously, the fuel injection time is not controlled with respect to the rotational speed, and the throttle valve is exclusively used. Since the fuel injection time is determined in accordance with the opening of the engine, if the opening of the throttle valve is constant, the amount of fuel injected will be the engine speed [rpm].
Irrespective of the situation.

However, when the injection time is determined irrespective of the rotational speed of the engine as described above, it becomes clear that the engine stops at a high speed or the output of the engine decreases. Was. It was also found that a two-stroke engine could burn at high speeds.

Therefore, in the injector control device proposed in which the control by the microcomputer and the control by the hardware circuit are used together, the engine is switched from the low-speed low-load state to the high-speed high load when the microcomputer is not operating normally. It was difficult to drive without any trouble to the state.

It is an object of the present invention to provide a method for controlling an injector for an internal combustion engine which can operate the engine from a low speed low load state to a high speed high load state without any trouble even when the microcomputer does not operate normally. It is to provide a control device used to carry out the method.

[0012]

In general, the amount of air flowing into a cylinder of an engine at each throttle opening increases with an increase in rotation speed. If the injection time is determined irrespective of the rotational speed of the engine, the amount of fuel supplied to the cylinder at the time of high speed of the engine becomes thin, and the above-described problem may occur.

Therefore, in the injector control method of the present invention, a steady-state injection command signal having a time width corresponding to the fuel injection time calculated by the microcomputer is supplied to the injector drive circuit in the steady state. Fuel is injected from the injector while the steady-state injection command signal is being generated, and in a case where the microcomputer is in a state where the microcomputer does not operate normally, in a case of an emergency, the hardware circuit increases the rotational speed of the engine in a predetermined speed range. The emergency injection command signal whose time width is widened is generated, and the emergency injection command signal is supplied to the injector drive circuit to inject the fuel from the injector.

The speed range in which the time width of the emergency injection command signal is widened may be the entire operating speed range of the engine, or may be only a partial speed range (for example, a middle-high speed range).

The inventions described in claims 2 to 5 are injector control devices for implementing the above method. In these inventions, the microcomputer calculates and calculates the fuel injection time according to various control conditions. A steady-state injection command signal generating section for generating a steady-state injection command signal having a time width corresponding to the fuel injection time, and generating an emergency injection command signal having a time width corresponding to the fuel injection time by a hardware circuit. When the emergency injection command signal generating section and the microcomputer are operating normally, a drive current is supplied to the injector while the steady-state injection command signal is being generated, and the microcomputer is in a state where the microcomputer does not operate normally. An injector drive circuit that sometimes supplies a drive current to the injector while the emergency injection command signal is being generated is provided.

The invention as set forth in claim 2, wherein the emergency injection command signal generating section generates an emergency injection command signal whose time width increases with an increase in the rotational speed of the internal combustion engine. In the above, the emergency injection command signal generation circuit generates a timing signal for injection time control at a predetermined rotation angle position of the internal combustion engine, and a control having a fixed time width triggered by the timing signal. A control signal generator for generating a signal, and an injection time signal generation circuit for performing an integration operation in which an integration interval is determined by the control signal and generating an injection time signal whose time width increases with an increase in engine speed. And an emergency injection command signal generation circuit that generates an emergency injection command signal during a period in which both the control signal and the injection time signal are generated.

According to a third aspect of the present invention, the fuel injection time at the start of the engine and in the low speed range can be set to an appropriate length. An injection time signal generating circuit similar to that described in claim 2, and a first injection command for generating a first injection command signal during a period in which both the control signal and the injection time signal are generated. A signal generation circuit, a second injection command signal generation circuit that generates a second injection command signal having a time width narrower than the control signal at the same time that the control signal is generated,
An emergency injection command signal output circuit that outputs an emergency injection command signal while the OR condition of the first injection command signal and the second injection command signal is satisfied.

The injection time signal generation circuit may be any circuit that generates a signal whose time width increases as the rotation speed increases as the injection time signal. The signal whose time width increases with an increase in the rotation speed is provided, for example, by providing an integration circuit in which the charging period or the discharging period of the integration capacitor changes in accordance with the rotation speed, and integrating the integration voltage obtained from the integration circuit. It can be obtained by comparing with a fixed reference voltage or another integrated voltage. Such an integration calculation method is used, for example, to calculate the ignition timing of an ignition device for an internal combustion engine. The configuration of the integration circuit that can be used to obtain a signal whose time width increases with an increase in the rotation speed is not one-way, and various modifications can be considered.
Preferred examples are shown in claims 4 and 5.

In the invention described in claim 4, the injection time signal generating circuit is configured to output the first time signal during the period during which no control signal is generated.
Is charged with a predetermined time constant to hold the voltage across the first integration capacitor while the control signal is being generated. When the control signal disappears, the first integration capacitor is charged. A first integrating circuit for performing an integrating operation for discharging almost instantaneously, and a second integrating capacitor for charging the second integrating capacitor almost instantaneously when the control signal disappears and for generating no control signal And a second integration circuit for performing an integration operation of discharging the second integration capacitor with a predetermined time constant during a period when the control signal is generated, and a voltage between both ends of the first integration capacitor. The first
And a comparator for comparing the integrated voltage of the first and second integrated capacitors with the second integrated voltage obtained at both ends of the second integrating capacitor, and the injection time from the comparator during the period in which the second integrated voltage exceeds the first integrated voltage Get the signal.

According to the fifth aspect of the present invention, the injection time signal generating circuit charges the first integration capacitor with a predetermined time constant during a period when the control signal is generated, and a period during which the control signal is generated. A first integration circuit for performing an integration operation for gradually discharging the first integration capacitor with a predetermined time constant;
While the control signal is being generated, the second integration capacitor is charged with a time constant smaller than the charging time constant of the first integration capacitor, and the second integration capacitor is discharged almost instantaneously when the control signal disappears. A second integration circuit that performs an integration operation; and a comparator that compares a first integration voltage obtained across both ends of the first integration capacitor with a second integration voltage obtained across both ends of the second integration capacitor. A firing time signal is generated from the comparator during a period when the first integrated voltage exceeds the second integrated voltage.

In carrying out the method of the present invention, the method of generating the emergency injection command signal is not limited to the method based on integral operation, but may be provided, for example, in a signal generator or a magnet generator attached to an internal combustion engine. The injection command signal may be generated when the output voltage of the generated coil exceeds a predetermined reference level. Since the output voltages of these generating coils increase as the rotational speed of the engine increases, the period during which the output voltage exceeds the reference level increases as the rotational speed increases.

[0022]

As described above, in the case of an emergency where the microcomputer does not operate normally, a hardware circuit generates an emergency injection command signal in which the time width increases with an increase in the rotation speed, and the emergency injection command signal is generated. If fuel is injected from the injector by supplying a time injection command signal to the injector drive circuit, the amount of fuel injected increases as the engine rotation speed increases. It is possible to prevent the supplied fuel from becoming thin, and to prevent the output of the engine from decreasing at a high speed, and to stop or burn the engine.

According to the second aspect of the present invention, the injection time signal is generated by performing the integration operation.
By appropriately setting the integration constant and the integration interval of the integration circuit, the maximum value of the time width of the injection time signal, the increase rate of the time width, and the like can be appropriately set, and the control of the fuel injection time can be appropriately performed. It can be made sure.

According to the third aspect of the present invention, when the OR condition of the first injection command signal and the second injection command signal having a time width narrower than the time width of the control signal is satisfied, the emergency injection signal is used. In order to generate the injection command signal, the injection time at a low speed of the engine is determined by the time width of the second injection command signal. Therefore, by appropriately setting the time width of the second injection command signal, it is possible to prevent the fuel injection amount from becoming insufficient or excessive when the engine is started or at a low speed, and And the driving performance at low speed can be improved.

In the injection time signal generating circuit according to the fourth aspect of the present invention, the first integrated voltage during the period in which the control signal is generated decreases as the engine speed increases, and the second integrated voltage decreases. Since the period during which the integrated voltage exceeds the first integrated voltage becomes longer, the time during which the injection time signal is generated becomes longer as the rotation speed of the engine increases. Therefore, the time width of the injection command signal increases as the engine speed increases, and the fuel injection amount increases as the engine speed increases. Since the emergency injection command signal is generated only during the period when both the injection time signal and the control signal are generated, the emergency injection time is saturated when the rotation speed increases to a certain value. If the fuel injection time saturates, the engine speed stops increasing, so if the fuel injection time saturates when the engine is running at high speed, an overspeed prevention function can be provided. Further, in the injection time signal generation circuit used in the invention described in claim 5, the discharge period of the first integrated voltage becomes shorter as the rotation speed increases, so that the level of the first integrated voltage becomes lower than the rotation speed. And the period during which the first integrated voltage exceeds the second integrated voltage becomes longer as the rotational speed increases. Accordingly, the time width of the injection time signal increases with an increase in the rotation speed, and the fuel injection time in an emergency increases with an increase in the rotation speed.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In an injector control method according to the present invention, a steady-state injection command signal having a time width corresponding to a fuel injection time calculated by the microcomputer is supplied to an injector drive circuit during a steady state in which the microcomputer operates normally. While the steady-state injection command signal is being generated, fuel is injected from the injector. In an emergency when the microcomputer is not operating properly, a hardware circuit generates an emergency injection command signal in which a time width is widened as the rotation speed increases in a predetermined speed range, and the emergency injection command signal is generated. A fuel injection command signal is supplied to an injector drive circuit to inject fuel.

An injector control device for carrying out the method of the present invention is configured as shown in FIG. In FIG. 1, reference numeral 10 denotes a steady-state injection command signal generation unit, 11 denotes an emergency injection command signal generation unit, and 12 denotes an injector drive circuit that supplies a drive current to the injector 13.

The steady-state injection command signal generator 10 is realized by a microcomputer 10A and a predetermined program for operating the microcomputer.
The output of a throttle sensor that detects the opening degree of the throttle valve, the output of various sensors such as a temperature sensor that detects the ambient temperature, and the output of a pressure sensor that detects the atmospheric pressure are input.
An injection command signal Vj 'for giving a fuel injection time is output. The steady-state injection command signal generator 10 may be the same as that used in a conventional fuel injection device for an internal combustion engine that controls the injection time by a microcomputer.

The emergency injection command signal generating unit 11 generates a timing signal for controlling the injection time at a predetermined rotational angle position of the internal combustion engine, and a predetermined time width triggered by the timing signal. A control signal generator 2 for generating a control signal Vq having the same and an integration operation in which an integration section is determined by the control signal Vq are performed, so that the time width becomes wider as the engine speed increases in a predetermined engine speed region. Injection time signal generation circuit 3 for generating an injection time signal Vx
And an emergency injection command signal generating circuit 4 for generating an emergency injection command signal Vj during a period in which both the control signal Vq and the injection time signal Vx are generated. A specific configuration example of the emergency injection command signal generator will be described later.

The injector drive circuit 12 supplies a switch circuit 5 for turning on / off a drive current supplied to a drive coil 13a of the injector 13 and a steady-state injection command signal Vj 'to a control terminal of the switch circuit 5 in a steady state. The switching circuit 6 supplies the emergency injection command signal Vj to the control terminal of the switching circuit 5. In a program for operating the microcomputer 10A, a check program for checking whether or not the microcomputer is operating normally is incorporated by a well-known method, and in a state where the microcomputer is operating normally, The microcomputer generates a high-level switching signal Ve, which is supplied to the control terminal of the switching circuit 6. The switching circuit 6 controls the microcomputer 1 when the switching signal Ve is given.
0 is supplied to the control terminal of the switch circuit 5, and when the supply of the switching signal Ve is stopped, the injection command signal Vj supplied from the emergency injection command signal 11 is supplied to the switch circuit 5. To the control terminal. The switch circuit 5 supplies a drive current to the drive coil 13a of the injector 13 while the injection command signal Vj 'or Vj is given from the switch circuit 6. The injector 13 injects fuel into the fuel injection space of the engine (usually in the throttle body) by opening its valve only while the drive current is being supplied.

In the apparatus shown in FIG. 1, when the microcomputer 10A operates normally, the injection command signal Vj 'output from the microcomputer is supplied to the control terminal of the switch circuit 5 through the switching circuit 6.
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 operation of the engine, the microcomputer 10A outputs the switching signal Ve. The switching circuit 6 supplies the emergency injection command signal Vj output from the emergency injection command signal generating section 11 to the control terminal of the switch circuit 5 in order to stop the output. Therefore, in an emergency when the microcomputer does not operate normally, the injection time of the fuel is controlled by the emergency injection command signal generation unit 11. Since the time width of the emergency injection command signal increases with an increase in the engine speed in a predetermined speed range, it is possible to prevent a shortage of fuel and a lean mixture at a high engine speed. Thus, it is possible to prevent the output from decreasing or the engine from stopping when the engine is running at high speed.

FIG. 2 shows an example of a specific configuration of the emergency injection command signal generating section 11 used in the control device for implementing the injector control method of the present invention. In FIG. 102 and a signal generator. The rotor 101 has a rotor 101a provided 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 is a known type including a core having a magnetic pole portion facing the rotor 101, a signal coil 102a wound around the core, and a permanent magnet magnetically coupled to the 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 generates pulsed signals Vs1 and Vs2 as shown in FIG.

The reluctor provided on the rotor 101 only needs to generate a magnetic flux change in the signal-emitting electron 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-described signal emission, but may use a semiconductor magnetic detection element such as a Hall IC to detect a change in magnetic flux generated by the reluctor. May be done.

In this embodiment, of the pulse signals obtained from the signal generator 1, the positive signal Vs1 is used as the timing signal. The mounting angle of the rotor 101 is set in advance so that the position where the timing signal Vs1 is generated becomes a position (fuel injection position) appropriate for starting fuel injection.

The timing signal Vs1 is supplied to the NPN transistor TR1 through the diode D1 and the resistor R1.
Is given to the base. The emitter of the transistor TR1 is grounded, and the output voltage E of a DC constant voltage power supply circuit (not shown) is applied to the collector of the transistor TR1 through a resistor R2.

The DC constant voltage power supply circuit is, for example, charged by an output coil provided in a magnet generator attached to an internal combustion engine, a rectifier circuit for rectifying the output of the output coil, and an output of the rectifier circuit. It comprises a power supply capacitor and a control circuit for controlling the voltage across the capacitor to be kept constant.

When the pulse signal Vs1 is applied to the transistor TR1 at time t1, the transistor TR1 conducts for a short time, and the potential of the collector drops instantaneously. A negative logic pulse signal Vp is obtained as shown in FIG. This pulse signal is applied to a trigger terminal of a monostable multivibrator M externally provided with a timed circuit comprising a resistor R3 and a capacitor C1. The multivibrator M is triggered by the falling edge of the pulse signal Vp and has its negative logic output terminal (Q bar terminal) at a zero level (grounded) from the triggered time t1 to a time t2 after a certain time Ts has elapsed from the triggered time t1. (A potential) is generated. The signal width Ts of the control signal Vq can be appropriately adjusted by the time constant of the timed circuit including the resistor R3 and the capacitor C1.

In this example, a waveform shaping circuit for shaping a timing signal generated by the signal generator into a pulse waveform is constituted by the transistor TR1, the diode D1 and the resistors R1 and R2. The waveform shaping circuit and the monostable multivibrator M constitutes a control signal generator 2 which is triggered by a timing signal and generates a control signal having a fixed time width.

The negative logic output terminal of the monostable multivibrator M is connected to one end of a first integrating capacitor C2 through a diode D2 and a resistor R4, and the other end of the integrating capacitor C2 is grounded. The non-ground terminal of the first integrating capacitor C2 is connected to the collector of a transistor TR2 whose emitter is grounded.
The negative logic output terminal of the monostable multivibrator M is connected to a base of the monostable multivibrator M through a capacitor C3 and a resistor R5. A diode D3 is connected between the connection point between the capacitor C3 and the resistor R5 and the ground.

In this embodiment, the first integration capacitor C2
, Diodes D2 and D3, transistor TR2,
The resistors R4 and R5 and the capacitor C3 constitute a first integrating circuit 3A. In the first integrating circuit, during a period in which the control signal Vq is not generated, the first integrating capacitor C2 is charged through the resistor R4 by a constant level voltage obtained at the negative logic output terminal of the monostable multivibrator M. . When the monostable multivibrator M generates the zero-level control signal Vq, the charging of the first integrating capacitor C2 is stopped, so that the voltage across the first integrating capacitor is maintained at the value at the end of charging. When the control signal Vq disappears (when the output voltage of the monostable multivibrator M rises), the capacitor C3 is charged through the space between the resistor R5 and the base-emitter of the transistor TR2, and the potential at the connection point between the capacitor C3 and the resistor R5. Vb instantaneously rises as shown in FIG. At this time, the transistor TR2 is turned on by the base current applied to the transistor TR2 for a short time, and the charge of the first integrating capacitor C2 is discharged instantaneously. The charge of the capacitor C3 is discharged instantaneously through the output circuit of the monostable multivibrator and the diode D3 when the control signal Vq is generated. Therefore, as shown in FIG. 3 (E), the maximum value during the period when the control signal Vq rises at a predetermined slope and the control signal Vq is generated is present at both ends of the first integration capacitor C2, as shown in FIG. And a first integrated voltage Vi1 having a waveform that returns to zero when the control signal Vq disappears is obtained.

The negative logic output terminal of the monostable multivibrator M is also connected to one end of a second integrating capacitor C4 through a resistor R6 having a sufficiently small resistance and a diode D4. The other end of the second integrating capacitor C4 is grounded, and a discharging resistor R7 is connected to both ends of the second integrating capacitor C4. A second integrating capacitor C4;
The resistors R6 and R7 and the diode D4 form a second integrating circuit 3B.

In the second integration circuit, the second integration capacitor C4 is charged almost instantaneously through the small resistor R6 while the control signal Vq is not generated, and the control signal Vq
Is generated, the second integrating capacitor C4 discharges through the resistor R7 with a constant time constant. Therefore, as shown in FIG. 3F, the control signal Vq rises almost instantaneously and maintains a constant value at both ends of the second integration capacitor C4 when the control signal Vq disappears, and the control signal Vq is generated. During this period, a second integrated voltage Vi2 having a waveform falling with a predetermined slope is obtained.

The first integrated voltage Vi1 and the second integrated voltage V
i2 is given to the inverting input terminal and the non-inverting input terminal of the comparator CP1, respectively. The comparator CP1 is shown in FIG.
As shown in the figure, the first integrated voltage Vi1 and the second integrated voltage V1
Compared with i2, as shown in FIG. 3 (H), an injection time signal Vx that maintains a high level while the second integrated voltage Vi2 exceeds the first integrated voltage Vi1 is output. In this example, the first integration circuit 3A, the second integration circuit 3B, and the comparator CP1 constitute the injection time signal generation circuit 3.

The output terminal of the comparator CP1 is connected to the output terminal of the DC constant voltage power supply circuit through the resistor R8 and to the collector of the NPN transistor TR3. The emitter of the transistor TR3 is grounded, and the base is connected to the negative logic output terminal of the monostable multivibrator M through a resistor R9. An emergency injection command signal generating circuit 4 is composed of the transistor TR3 and the resistors R8 and R9. In this circuit, the transistor TR3 keeps the cut-off state while the control signal Vq is generated, and keeps the conductive state while the control signal Vq is not generated. Therefore, a rectangular wave signal Vq 'having a waveform obtained by inverting the control signal Vq is obtained at the collector of the transistor TR3 as shown in FIG. Transistor TR3
Is connected to the output terminal of the comparator CP1.
Since the AND circuit is configured, the transistor TR3
The square wave signal Vq 'and the injection time signal Vx
During the period in which the AND condition is satisfied, a rectangular wave emergency injection command signal Vj as shown in FIG. 3 (J) is obtained. This injection command signal Vj is given to the injector drive circuit 12 of FIG.

FIGS. 4A to 4D show the signals Vs1 and Vs2 when the rotation speed of the internal combustion engine is high, and the control signal Vq.
And the waveforms of the integral voltages Vi1 and Vi2 and the injection command signal Vj. FIGS. 4E to 4H show signals Vs1 and Vs2, control signal Vq, integrated voltages Vi1 and Vi2, and injection command signal V when the rotation speed of the internal combustion engine is low.
The waveform with j is shown.

When the rotation speed of the internal combustion engine is low, FIG.
As shown in (E), since the generation interval (time) of the timing signal Vs1 is long and the time for charging the first integration capacitor C2 is long, the first integration voltage Vi1 at time t1 is obtained.
Has increased. Therefore, as shown in FIG. 4H, the time width (fuel injection time) T of the injection command signal Vj
s is shorter.

As the rotation speed of the internal combustion engine increases, the interval of generation of the timing signal Vs1 becomes shorter, as shown in FIG. 4A, and the time for charging the second integration capacitor C2 becomes shorter. Therefore, the value of the first integrated voltage Vi1 at the time t1 becomes smaller. Therefore, FIG.
As shown in (D), the time width (fuel injection time) Tj of the injection command signal Vj increases as the rotation speed increases.

In the above embodiment, if the charging time constant τ = C2 R4 of the first integrating capacitor C2 is adjusted, the characteristics of the injection time Tj with respect to the rotation speed N can be adjusted. That is, the characteristics of the injection time Tj with respect to the rotation speed N when the charging time constant τ is τ1 and τ2 (> τ1) are as shown in FIG. 5, and by reducing the time constant τ, the rotation speed can be reduced. The rate of increase of the injection time with respect to the rise can be increased. Therefore, by adjusting the time constant τ, it is possible to obtain a characteristic of rapidly increasing the fuel as the rotation speed of the internal combustion engine increases, and a characteristic of gradually increasing the fuel as the rotation speed increases. Various requests from the engine can be met.

In the above embodiment, the injection time signal V
Since the emergency injection command signal Vj is generated when the AND condition between x and the control signal Vq is satisfied, the time width of the injection command signal Vj is limited by the time width of the control signal Vq. That is, when the rotation speed exceeds the set value Ns, the time width of the injection command signal Vj saturates to the time width Ts of the control signal Vq (the fuel injection duty becomes 100%). The set value Ns of the rotational speed at which the time width of the injection command signal Vj is saturated
Can be appropriately adjusted by adjusting the time constant of the timed circuit composed of the resistor R3 and the capacitor C1 and adjusting the time width Ts of the control signal Vq generated by the monostable multivibrator M. Fuel injection duty is 100%
Then, since the rotation speed of the engine does not further increase, the upper limit of the rotation speed of the engine can be appropriately set by adjusting the signal width Ts, and an overspeed prevention function can be provided.

In the above embodiment, the timing signal is generated only once per rotation of the engine. However, the timing signal may be generated a plurality of times per rotation of the engine.

FIG. 6 shows an emergency injection command signal generator 11.
In this example, the output of the positive logic output terminal (Q terminal) of the monostable multivibrator M is applied to a first integrating capacitor C11 through a resistor R11, and is also output through a resistor R12. Second integration capacitor C
The diode D12 is connected to both ends of the resistor R12 and the cathode is directed to the positive logic output terminal side of the monostable multivibrator. A first integrating circuit 3A is constituted by the resistor R11 and the first integrating capacitor C11.
12, a second integrating capacitor C12, and a diode D12 constitute a second integrating circuit 3B.

The first integrated voltage Vi1 obtained at both ends of the first integrating capacitor C11 is inputted to the non-inverting input terminal of the comparator CP1, and the second integrated voltage Vi2 obtained at both ends of the second integrating capacitor C12. Is input to the inverting input terminal of the comparator CP2. The negative logic output terminal (Q bar terminal) of the monostable multivibrator M is connected to the base of the transistor TR3 through the resistor R9. The configuration of the control signal generator 2 is the same as that of the embodiment shown in FIG.

In the embodiment shown in FIG. 6, a rectangular wave signal obtained at the positive logic output terminal of the monostable multivibrator M is used as the control signal Vq (see FIG. 7C). This control signal Vq is applied to the first integrating capacitor C11 through the resistor R11, so that the first integrating capacitor C11
It is charged with a time constant determined by 11 and the capacitor C11. Therefore, the voltage across the first integrating capacitor C11 increases with a constant gradient while the control signal Vq is being generated. The charge of the first integrating capacitor C11 is obtained by controlling the control signal Vq
During the period in which is disappeared, discharge is gradually performed through the resistor R11 and the output circuit of the positive logic output terminal of the monostable multivibrator. Therefore, as shown in FIG. 7 (D), both ends of the first integrating capacitor C11 rise at a predetermined gradient during the period Ts during which the control signal Vq is generated, and are at intervals during which the control signal Vq is not generated. A first integrated voltage Vi1 having a waveform falling at a predetermined inclination is obtained.

The control signal Vq is also applied to the second signal through the resistor R12.
Control signal Vq
Is generated, the second integrating capacitor C12 is charged with a constant time constant. The charging time constant of the second integration capacitor is set smaller than the charging time constant of the first integration capacitor C11. When the control signal Vq disappears, the electric charge of the second integrating capacitor C12 is discharged almost instantaneously through the diode D12 and the output circuit of the monostable multivibrator M. Accordingly, as shown in FIG. 7 (E), both ends of the second integration capacitor C12 rise with a larger gradient than the first integration voltage Vi1 during the generation of the control signal Vq, and the control signal Vq rises. A second integrated voltage Vi2 having a waveform that returns to zero almost instantaneously when it disappears is obtained.

The first and second integrated voltages Vi1 and Vi2 are compared by a comparator CP1, and the first integrated voltage Vi1 is compared with the second integrated voltage Vi1.
During the period exceeding the integrated voltage Vi2, the comparator CP1 generates the injection time signal Vx.

Since the transistor TR3 keeps the cut-off state while the control signal Vq is being generated, a rectangular wave signal similar to the control signal Vq is obtained at the collector of the transistor TR3. Since the collector of the transistor TR3 and the output terminal of the comparator CP1 are connected to form an AND circuit, the collector of the transistor TR3 has a period during which the AND condition between the control signal Vq and the injection time signal Vx is satisfied. 7 (H), an emergency injection command signal Vj in the form of a rectangular wave is obtained.

While the engine speed is low, the discharge time of the first integration capacitor C11 is long, so that the peak value of the first integration voltage Vi1 is low as shown in FIG. 7 (F). Therefore, when the engine is running at a low speed, the period during which the first integrated voltage Vi1 exceeds the second integrated voltage Vi2 is shortened, and the time width of the injection time signal Vx is narrowed.

On the other hand, when the engine is running at a high speed, the discharge time of the first integration capacitor Ci1 is short, so that the peak value of the first integration voltage Vi1 is high. Therefore, when the engine is running at high speed, the period during which the first integrated voltage Vi1 exceeds the second integrated voltage Vi2 becomes longer, and the time width of the injection time signal Vx becomes longer.

Since the emergency injection command signal Vj is generated when the AND condition between the control signal Vq and the injection time signal Vx is satisfied, the time width of the injection command signal Vj is controlled by the control signal Vq
Is limited by the time width Ts.

FIG. 9 shows another example of the configuration of the emergency injection command signal generator used in the present invention.
The emergency injection command signal generation circuit used in the example of FIG.
The injection command signal obtained from the injection command signal generation circuit 4A is referred to as a first injection command signal Vj1, and the second is composed of transistors TR4 and TR5, resistors R13 to R15, a capacitor C13 and a diode D13. , And an emergency injection command signal output circuit 4C composed of an OR circuit constituted by diodes D14 and D15.

FIG. 10 and FIG. 11 show signal waveforms at various points in the embodiment shown in FIG. FIG. 10 shows a waveform when the rotation speed is low, and FIG. 10 shows a waveform when the rotation speed is high. In the example shown in FIG. 9, when the control signal Vq is not generated, the transistor TR5 is turned off and the transistor TR4 is turned on. At this time, the potential of the collector of the transistor TR4 is substantially at the ground potential. When the control signal Vq is generated, a base current flows through the transistor TR5 through the capacitor C13 and the resistor R13. When the base current exceeds a predetermined trigger level Vt, the transistor TR5 conducts. Transistor TR
5 conducts, the base current is supplied from the power supply through the resistor R14, and the transistor TR4 that has been conducting
Is turned off, the potential of the collector of the transistor TR4 rises. When the charging of the capacitor C13 approaches the end and the charging current becomes equal to or lower than the trigger level Vt of the transistor, the transistor TR5 is turned off, so that the transistor TR4 is turned on and the potential of the collector of the transistor TR4 is almost at the ground potential. Down to Point A (capacitor C) when the control signal Vq is generated
The change in the potential of the node 13 and the resistor R13) is shown in FIG.
(H) or FIG. 11 (F), and the change in the potential of the collector of the transistor TR4 is as shown in FIG. 10 (I) or FIG. 11 (G). Since the charging time constant of the capacitor C13 is constant, the time width of the rectangular wave signal obtained at the collector of the transistor TR4 is constant. In the present embodiment, this rectangular wave signal is used as the second injection command signal Vj2. The time width of the second injection command signal Vj2 is set to be smaller than the time width Ts of the control signal, and to be equal to the injection time suitable for starting the engine and at low speed. The time width To of the second injection command signal Vj2 is determined by the capacitor C13.
And the resistance value of the resistor R13 can be appropriately set.

The OR circuit (emergency injection command signal output circuit) 4C including the diodes D14 and D15 is used during an emergency condition while the OR condition of the first injection command signal Vj1 and the second injection command signal Vj2 is satisfied. And outputs the injection command signal Vj. At the start of the engine and at low speed, FIG.
As shown in (I), since the time width of the first injection command signal Vj1 is narrower than the time width of the second injection command signal Vj2,
The time width of the emergency injection command signal Vj is determined by the time width To of the second injection command signal Vj2, and the fuel injection time Tj is constant (= To) as shown in FIG. When the rotational speed of the engine exceeds the set value Ns1, the time width of the first injection command signal Vj1 becomes wider than the time width of the second injection command signal Vj2. It is determined by the time width of the first injection command signal Vj1. Therefore, in a region where the rotation speed exceeds the set value Ns1, the fuel injection time Tj becomes longer as the rotation speed N increases. When the rotation speed exceeds the set value Ns2, the time width of the first injection command signal Vj1 exceeds the time width of the control signal Vq.
Since the first injection command signal Vj is generated only during a period during which the AND condition between the injection time signal Vx and the control signal Vq is satisfied, the time width of the first injection command signal is the time width Ts of the control signal Vq. Is limited by Therefore, in the region where the rotational speed exceeds the set value Ns2, the time width of the emergency injection command signal Vj is equal to the time width Ts of the control signal Vq, and the injection time Tj is equal to the time width Ts of the control signal Vq. FIG.
In FIG. 2, a straight line a indicates a change of the first injection command signal Vj1 with respect to the rotation speed N, and a straight line B indicates a change of the second injection command signal Vj2 with respect to the rotation speed. A solid line C shown by a solid line indicates the injection time Tj versus rotational speed N characteristic obtained by the embodiment of FIG.

In the embodiment of FIG. 9, the first and second integration circuits are constructed in the same manner as in the embodiment of FIG. 6, but when an integration circuit of another configuration is used, for example, the first and second integration circuits may be used. Even when the integration circuit is configured as in the embodiment of FIG. 2, by providing a circuit that generates a second injection command signal having a width smaller than that of the control signal at the same time that the control signal is generated, and an OR circuit, The injection time in the low speed region of the engine can be made constant.

In each of the embodiments described above, the injection time at each rotational speed is determined by an integral operation. However, in implementing the method of the present invention, at least the medium-high-speed region is specified using a hardware circuit. In this speed range, an emergency injection command signal whose time width increases with an increase in the rotation speed may be obtained, and it is not always necessary to determine the injection time by integral calculation.

For example, as shown in FIG. 13, a signal generator 1 supplies a base current through a diode D and a resistor R to a transistor TRi in which a collector-emitter circuit is connected in series to a drive coil 13a of an injector 13. By adopting the configuration, a characteristic may be obtained in which the injection time is increased as the rotation speed increases.

In the example shown in FIG. 13, an emergency injection command signal generating section is constituted by the signal generator 1 and the diode D, and the output voltage of the positive and negative half cycles obtained from the signal generator 1 is obtained. Are used as the emergency injection command signal Vj. The transistor TRi constitutes a switch circuit for turning on / off the drive current for the injector. In such a configuration, as shown in FIG. 14A, the signal generator 1 generates signals V1 and V1 'having a waveform close to a sine wave.

The waveforms V1a and V1b in FIG. 14B show the waveform of the output voltage V1 in the positive half cycle of the signal generator 1 when the rotational speeds are Na and Nb (> Na), respectively. (C) and (D) show that the rotation speed is Na
And Nb, the drive current flowing through the drive coil of the injector is approximated by a rectangular wave. As shown in the figure, the peak value and the time width of the output voltage V1 of the signal generator 1 become wider as the rotation speed increases. Therefore, when the trigger level of the transistor TRi is set to Vb, the rotation speeds are Na and Nb. The drive current Ija
And Ijb flow periods Tja and Tjb are 14
As shown in (C) and (D), in the speed region where the time width of the voltage V1 becomes wider as the rotation speed increases, the fuel injection time becomes longer as the rotation speed increases. Go.

When the configuration shown in FIG. 13 is used, instead of using the dedicated signal generator 1, a power generation coil provided in a magnet generator attached to the internal combustion engine is used as a signal source, and the output of the power generation coil is used. Can be supplied to the base of the transistor TRi through the diode D and the resistor R.

[0071]

As described above, according to the present invention, in the case of an emergency in which the microcomputer is not operating normally, the emergency injection command in which the time width is widened as the rotational speed is increased by the hardware circuit. The fuel is injected from the injector by generating a signal and supplying the emergency injection command signal to the injector drive circuit. Therefore, even in an emergency, the fuel injection amount is increased with the rotation speed of the engine. Can be increased. Therefore, it is possible to prevent the fuel supplied to the cylinder of the engine from becoming thin at a high speed, and to prevent the output of the engine from decreasing at a high speed, or to stop or burn the engine.

According to the second aspect of the present invention, an injection time signal for determining the fuel injection time is generated by performing an integration operation, so that the integration constant and the integration interval of the integration circuit are appropriately set. The maximum value of the time width of the injection time signal, the rate of increase of the time width, and the like can be appropriately set, and the control of the fuel injection time can be performed accurately.

According to the third aspect of the present invention, when an OR condition between the first injection command signal and the second injection command signal having a time width narrower than the time width of the control signal is satisfied, an emergency In order to generate the injection command signal for use, the injection time at the time of low speed of the engine can be determined by the time width of the second injection command signal, and the time width of the second injection command signal is set appropriately. In this way, it is possible to prevent the fuel injection amount from becoming insufficient or excessive when the engine is started and at a low speed, and to improve the engine start performance and the low-speed operation performance.

According to the fourth or fifth aspect of the invention, the emergency injection command signal is generated only during the period when both the injection time signal and the control signal are generated.
Since the injection time in an emergency is limited to the time width of the control signal, the fuel injection time can be saturated at a high speed to provide an overspeed prevention function.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration of an apparatus for implementing a method of the present invention.

FIG. 2 is a circuit diagram showing a specific configuration example of an emergency injection command signal generator used in the apparatus of FIG.

FIG. 3 is a waveform chart showing signal waveforms at various parts in FIG. 1;

FIG. 4 is a waveform diagram showing signal waveforms of various parts when the engine is at low speed and at high speed.

FIG. 5 is a diagram showing an example of an injection time versus rotation speed characteristic obtained by an embodiment of the present invention.

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

FIG. 7 is a waveform chart showing signal waveforms of various parts at the time of low speed in FIG. 6;

FIG. 8 is a waveform diagram showing signal waveforms of various parts at the time of high speed in FIG. 6;

FIG. 9 is a circuit diagram showing still another configuration example of the emergency injection command signal generation unit used in the present invention.

FIG. 10 is a waveform chart showing signal waveforms of various parts at the time of low speed in FIG. 9;

FIG. 11 is a waveform diagram showing signal waveforms of various parts at the time of high speed in FIG. 9;

12 is a diagram showing an example of an injection time versus rotation speed characteristic obtained when the emergency injection command signal generator of FIG. 9 is used.

FIG. 13 is a circuit diagram showing still another configuration example of the emergency injection command signal generation unit used in the present invention.

FIG. 14 is a waveform diagram showing voltage and current waveforms of respective parts in FIG.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 signal generator 2 control signal generator 3 injection time signal generation circuit 3A first integration circuit 3B second integration circuit 4 emergency injection command signal generation circuit 4A first injection command signal generation circuit 4B second injection Command signal generation circuit 4C Injection command signal output circuit (OR circuit) 10 Injection command signal generator for regular operation 11 Injection command signal generator for emergency 12 Injector drive circuit 13 Injector CP1 Comparator C1 Capacitor C2 First integration capacitor C4 Second integrating capacitor M Monostable multivibrator TR1 to TR5 Transistor C11 First integrating capacitor C12 Second integrating capacitor C13 Capacitor R1 to R9 Resistance R11 to R15 Resistance D1 to D4 Diode D12 to D15 Diode

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F02D 41/22 325 F02D 41/20 330 F02D 41/20 380

Claims (5)

(57) [Claims] A steady-state injection command signal having a time width corresponding to a fuel injection time calculated by a microcomputer is supplied to an injector drive circuit in a steady state, and the injector is operated while the steady-state injection command signal is being generated. In the event of an emergency in which the microcomputer is not operating properly, the hardware circuit generates an emergency injection command signal in which the time width increases as the rotational speed increases in a predetermined speed range. And supplying the emergency injection command signal to the injector drive circuit to inject fuel. 2. A steady-state injection command signal for generating a steady-state injection command signal having a time width corresponding to the calculated fuel injection time by calculating a fuel injection time according to various control conditions by a microcomputer. An emergency injection command signal generating section for generating an emergency injection command signal having a time width corresponding to the fuel injection time by a hardware circuit, and the steady-state injection when the microcomputer is operating normally. An injector drive circuit that supplies a drive current to the injector while the command signal is being generated, and supplies a drive current to the injector while the emergency injection command signal is being generated in an emergency when the microcomputer is not operating properly. An injector control device for an internal combustion engine comprising: an emergency injection command signal generating unit, A signal generator for generating a timing signal for controlling the injection time at the turning angle position, a control signal generator for generating a control signal having a fixed time width triggered by the timing signal, and an integration interval according to the control signal. An injection time signal generating circuit that performs an integral operation that is determined and generates an injection time signal whose time width increases with an increase in the rotation speed of the engine, and both the control signal and the injection time signal are generated. An emergency injection command signal generating circuit for generating the emergency injection command signal for a period of time. 3. A steady-state injection command signal that generates a steady-state injection command signal having a time width corresponding to the calculated fuel injection time by calculating a fuel injection time according to various control conditions by a microcomputer. An emergency injection command signal generating section for generating an emergency injection command signal having a time width corresponding to the fuel injection time by a hardware circuit, and the steady-state injection when the microcomputer is operating normally. An injector drive circuit that supplies a drive current to the injector while the command signal is being generated, and supplies a drive current to the injector while the emergency injection command signal is being generated in an emergency when the microcomputer is not operating properly. An injector control device for an internal combustion engine comprising: an emergency injection command signal generating unit, A signal generator for generating a timing signal for controlling the injection time at the turning angle position, a control signal generator for generating a control signal having a fixed time width triggered by the timing signal, and an integration interval according to the control signal. An injection time signal generating circuit that performs an integral operation that is determined and generates an injection time signal whose time width increases with an increase in the rotation speed of the engine, and both the control signal and the injection time signal are generated. A first injection command signal generating circuit for generating a first injection command signal for a period of time, and a second injection for generating a second injection command signal having a shorter time width than the control signal at the same time as the control signal is generated. A command signal generation circuit, and an emergency injection command signal output for outputting the emergency injection command signal during a period when an OR condition of the first injection command signal and the second injection command signal is satisfied. An internal combustion engine injector control apparatus characterized in that it comprises a circuit. 4. The injection time signal generation circuit charges a first integration capacitor with a predetermined time constant during a period in which the control signal is not generated, and supplies the first integration capacitor during a period in which the control signal is generated. Holds the voltage across the capacitor,
A first integration circuit that performs an integration operation to discharge the first integration capacitor almost instantaneously when the control signal disappears, and charges a second integration capacitor almost instantaneously when the control signal disappears. In the integration operation, the voltage across the second integration capacitor is held during a period in which the control signal is not generated, and the second integration capacitor is discharged with a predetermined time constant during a period in which the control signal is generated. A second integration circuit for performing the operation, and a comparator for comparing a first integration voltage obtained across the first integration capacitor with a second integration voltage obtained across both ends of the second integration capacitor, 4. The injector control device for an internal combustion engine according to claim 2, wherein the injection time signal is obtained from the comparator during a period in which the second integrated voltage exceeds the first integrated voltage. 5. The injection time signal generation circuit charges a first integration capacitor with a predetermined time constant during a period in which the control signal is generated, and charges the first integration capacitor during a period in which the control signal is generated. A first integration circuit that performs an integration operation for gradually discharging a capacitor with a predetermined time constant; and a second integration circuit that has a time constant smaller than a charging time constant of the first integration capacitor while the control signal is being generated. A second integration circuit for performing an integration operation for charging the integration capacitor and discharging the second integration capacitor almost instantaneously when the control signal disappears; a first integration obtained at both ends of the first integration capacitor; A comparator for comparing a voltage with a second integrated voltage obtained between both ends of a second integrating capacitor, wherein the injection time from the comparator during a period in which the first integrated voltage exceeds the second integrated voltage Getting a signal An internal combustion engine injector control apparatus according to claim 2 or 3, characterized.