JPH0727008A - Injector driver for internal combustion engine - Google Patents

Abstract

PURPOSE:To get proper air-fuel ratio by controlling the injection time of fuel even at emergency when a microcomputer can not operate properly. CONSTITUTION:This driver is provided with an injection command signal generator 11 for hard control, which generates an injection command signal Vj at emergency, and fuel is injected by driving an injector while the injection command signals Vj are generated. Each time the signal generating means 11A generates a timing signal, a rectangular wave signal generating circuit 11B generates a rectangular injection command signal Vj. The signal width deciding circuit 6 of the rectangular signal generating circuit 11B is provided with a thermosensitive resistance element Rt2, and the injection time of the fuel is changed according to the temperature of intake by narrowing the signal width of the injection command signal Vj, accompanying the rise of intake temperature, thus the fuel is prevented from becoming thin or thick by the change in intake temperature.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art In order to operate an internal combustion engine in an optimum state, it is important to control the air-fuel ratio appropriately according to the temperature of each part of the engine, the rotation speed and the like. When fuel is supplied to the engine by the injector, the fuel injection amount is determined by the time (fuel injection time) for injecting the fuel from the injector and the pressure (fuel pressure) of the fuel applied to the injector. Also, since the air-fuel ratio is affected by temperature and atmospheric pressure, in order to accurately control the air-fuel ratio, it is necessary to accurately control the fuel injection time according to the control conditions such as atmospheric pressure and the temperature of each part. Is.

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 inputs the information such as the atmospheric pressure and the temperature given from the sensor and the output of the signal generator to calculate the fuel injection position (the rotation angle position at which the fuel injection is started) and the fuel injection time, An injection command signal including information on the calculated fuel injection time is given to the injector drive circuit at the calculated fuel injection position. This injection command signal consists of, for example, a rectangular wave signal that rises at the fuel injection position and has a signal width equal to the fuel injection time, and the injector drive circuit gives 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 being applied.

In this type of fuel injection device, fuel is not injected when the voltage of the power source of the microcomputer is lowered and the microcomputer is not operating. Therefore, for example, when the engine is started, the power source voltage of the microcomputer is reduced. If it is low, the engine cannot be started.

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

Further, even when the power supply of the microcomputer is secured, if the CPU malfunctions or the cylinders of the multi-cylinder internal combustion engine cannot be discriminated, the control by the microcomputer should be properly performed. Can not be.

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

This proposed control apparatus calculates a fuel injection time according to various control conditions by a microcomputer and outputs a signal of a time width corresponding to the calculated fuel injection time as a soft control injection command signal. An injection command signal generator for soft control to be generated, and an injection command signal generator for hardware control to generate a signal having a time width corresponding to a predetermined fuel injection time as a hardware control injection command signal using a hardware circuit. , When the microcomputer is operating normally, the drive current is supplied to the injector while the soft control injection command signal is generated, and in the emergency when the microcomputer is not operating normally, the hard control injection command signal is An injector drive circuit is provided which supplies a drive current to the injector during generation.

FIG. 12 shows the structure of a hard control injection command signal generator used in a conventional injector drive system. In FIG. 12, reference numeral 1 denotes a signal generator mounted on an internal combustion engine. The signal generator 1 includes a rotor 101 having a reluctor 101a on the outer periphery thereof, and a signal generator 10.
It is a well-known one composed of 2 and. The signal generator 102
The rotor 10 includes a signal coil 102a wound around an iron core having magnetic pole portions facing the outer peripheral portion of the rotor 101, and a permanent magnet (not shown) magnetically coupled to the iron core.
1 reluctor induces positive and negative polarity pulse signals Vs1 and Vs2 in the signal coil 102a due to changes in magnetic flux generated when the reluctor 1 starts to face the magnetic pole portion of the iron core of the signal emitting electron 102 and when the facing ends. To do. A positive polarity pulse signal Vs1 generated at the end of these pulse signals is input as a timing signal Vt for injector control through a diode 4 to a trigger terminal (TRG) of a monostable multivibrator 5 composed of an IC.

A capacitor C is connected between the external capacitor / resistor connection terminal Tn and the ground terminal GND of the monostable multivibrator 5, and a resistor Ro, a resistor R1 and a resistor R1 are provided between the terminal Tn and the power supply terminal E. A parallel circuit of the temperature sensitive resistance element Rt1 is connected in series, and a switch S is connected to both ends of the resistor R1. Capacitor C and resistors Ro and R
1 and the temperature sensitive resistance element Rt1 constitute a signal width determination circuit 6 ', and the signal width (time width) of the rectangular wave signal Vj output by the monostable multivibrator 5 is determined by the time constant of this signal width determination circuit. Has been decided. The resistor Ro of the signal width determination circuit 6'is a fixed resistor that gives the basic injection time to, and this fixed resistor Ro is for determining the injection time at room temperature (20 ° C.), for example. The parallel circuit of the resistor R1 and the temperature-sensitive resistance element Rt1 is a starting injection time correction resistance circuit that gives a starting increase correction time Ta that is added to the basic injection time To in order to increase the fuel when the engine is started. . As the temperature sensitive resistance element Rt1,
A temperature sensitive resistance element R having a negative temperature coefficient is used.
The resistance value of the resistor R1 connected in parallel at both ends of t1 is appropriately set, and the parallel combined value of the resistors R1 and Rt1 and the change amount thereof due to the temperature change are adjusted.

The signal obtained from the signal generator 1 is also given to the rotation speed detection circuit 7. The rotation speed detection circuit 7 detects the rotation speed of the engine from the output frequency of the signal generator 1,
When the detected number of rotations reaches the set value, a trigger signal is given to the switch S to make the switch S conductive.

In the circuit shown in FIG. 12, the monostable multivibrator 5 outputs a rectangular-wave-shaped hard control injection command signal Vj having a predetermined time width from its output terminal Q every time the timing signal Vt is applied. The signal width of the injection command signal Vj is determined by the time constant of the signal width determination circuit 6 '.

In an emergency when the microcomputer does not operate normally, for example, when the engine is not started and the power supply for the microcomputer is not started, the injector drive circuit operates while the hard control injection command signal Vj is generated. Apply drive current to the injector. The injector opens its valve while the drive current is being applied and injects fuel into the intake pipe of the engine. That is, the time width of the hard control injection command signal Vj becomes the fuel injection time in an emergency.

When the engine is started, the switch S is opened and the time constant of the signal width determining circuit 6'is large, so that the signal width of the hard control injection command signal Vj is wide and the fuel injection time is long. Then, the increase control at the time of starting is performed. Since the resistance value of the temperature sensitive resistance element Rt increases as the air temperature decreases, the signal width of the injection command signal Vj becomes wider and the fuel injection time becomes longer as the air temperature becomes lower. Therefore, the fuel injection time at the start of the engine changes as shown in FIG. 13 with respect to the air temperature.

When the engine speed reaches a set value after the engine is started, the switch S is closed, so that the injection command signal V
The signal width of j is determined by the product of the resistance value of the resistor Ro and the electrostatic capacitance of the capacitor C. Therefore, when the microcomputer does not operate normally, the signal width of the injection command signal Vj during the steady operation of the engine becomes constant regardless of the air temperature.

[0016]

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

That is, since the mass of air decreases as the air temperature rises, the fuel injection time (interval between required injections) required to obtain a certain air-fuel ratio when the volume of intake air is constant. ) Becomes shorter as the air temperature rises, as indicated by the straight line a in FIG. Therefore, in order to keep the air-fuel ratio within the proper range, it is necessary to shorten the fuel injection time as the intake air temperature rises.

However, the conventional hardware control injection command signal generator does not control the time width of the injection command signal during the steady operation of the engine with respect to the intake air temperature, and in an emergency when the microcomputer does not operate normally, When the engine was operated by setting the time for giving the drive current to the injector by the hard control injection command signal, it was not possible to obtain an appropriate air-fuel ratio, so various troubles might occur.

For example, as indicated by the straight line b in FIG. 14, the resistance value of the resistor Ro is set so that the signal width of the injection command signal during steady operation is equal to the magnitude corresponding to the required injection time at 20 ° C. In the region where the air temperature is lower than 20 ° C, the fuel becomes lean (lean), and abnormal heat generation of the engine, abnormal increase in rotation speed, backfire, etc. are likely to occur, and in the worst case, There was a risk of engine stall or damage. Also, the air temperature is 20
If the temperature is higher than 0 ° C, the fuel becomes too rich (becomes rich) and the spark plug is fogged, so that HC in the exhaust gas may increase or engine stall may occur.

An object of the present invention is to control the fuel injection time according to the air temperature in a state where the injector is driven by the injection command signal obtained from the hard control injection command signal generating section to drive the engine. It is an object of the present invention to provide an injector drive device for an internal combustion engine, which can prevent troubles such as abnormal heat generation of the engine, abnormal increase of rotation speed, increase of HC in exhaust gas, engine stall and the like.

[0021]

The present invention calculates a fuel injection time by a microcomputer 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 generator, a hardware control injection command signal generator that generates a hardware control injection command signal with a time width corresponding to the fuel injection time, and the microcomputer operate normally. Drive current is supplied to the injector while the soft control injection command signal is generated, and the injector is driven while the hard control injection command signal is generated when the microcomputer does not operate normally. The present invention relates to an injector drive device for an internal combustion engine, which includes an injector drive circuit that supplies current.

In the present invention, the hard control injection command signal generating section has a timing signal generating means for generating a timing signal at a fuel injection position of the internal combustion engine, and a signal width determining circuit to provide the timing signal. And a rectangular wave signal generation circuit for generating a rectangular wave signal having a signal width determined by the signal width determination circuit for each as a hard control injection command signal. Here, the signal width determination circuit is a starting injection time adjustment element having a characteristic that impedance changes according to temperature, a steady operation injection time adjustment element having a characteristic that impedance changes with temperature, and an internal combustion engine The circuit configuration of the signal width determination circuit so that the starting injection time adjusting element works effectively when the rotation speed is less than the set value, and the steady operation injection time adjusting element works effectively when the rotation speed reaches the set value. And a switching means for switching the start-up injection time adjusting element and steady-state operation so that the signal width of the rectangular-wave signal generated by the rectangular-wave signal generating circuit at the time of startup and steady operation is shortened as the temperature rises. The temperature characteristic of the hour injection time adjusting element is set.

The phrase "the injection time adjusting element works effectively" means that the adjusting element serves as one of the elements for determining the signal width of the rectangular wave signal.

Each of the injection time adjusting element for starting and the injection time adjusting element for steady operation can be constituted by a resistance circuit including a temperature sensitive resistance element whose resistance value changes with temperature.

The starting injection time adjusting element and the steady operation injection time adjusting element can be provided in a state of being connected in series with each other. In this case, the switch means is connected in parallel to both ends of the starting injection time adjusting element so that when the rotational speed of the internal combustion engine reaches a set value, the switch means conducts to short-circuit the starting injection time adjusting element. Leave.

[0026]

As described above, the adjusting element of the signal width determining circuit that determines the signal width is given a temperature characteristic to generate a rectangular wave signal whose signal width narrows as the temperature rises. When the injection command signal for hardware control is used, even when the engine is operated in a state where the microcomputer does not operate normally, the air-fuel ratio can be maintained in an appropriate state with respect to changes in intake air temperature, and the engine can be operated without hindrance. be able to.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the overall construction of an embodiment of the present invention. In FIG. 1, 10 is a soft control injection command signal generation unit, 11 is a hard control injection command signal generation unit, 12 is an injector drive circuit for supplying a drive current to an injector 13, and 14 is a magnet generator installed in an internal combustion engine. This is a power supply circuit that outputs a constant DC voltage using the provided power generation coil 15 as a power supply.

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

The injection command signal generator 11 for hardware control is
A signal generator 11A, which is driven by the internal combustion engine, is provided with a signal generator 11A for generating a timing signal Vt for controlling the injection time at a predetermined rotational angle position of the internal combustion engine, and a signal width determining circuit. It is composed of a rectangular wave signal generating circuit 11B which 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 hard control injection command signal generation unit will be described later.

The output of the signal generator 1 is also given to the microcomputer 11A through a waveform shaping circuit (not shown). The microcomputer 11A is a signal generator 1
The engine rotation angle information and the engine speed information are obtained from the output of 1 to calculate the fuel injection position and the fuel injection time at each rotation speed.

The injector drive circuit 12 supplies a drive current to the injector 13 while the soft control injection command signal Vj 'is generated when the microcomputer is in a state where it can operate normally, and the microcomputer operates normally. When not in the state, the switching circuit 12A and the switch 12B are circuits that give a drive current to the injector 13 while the hard control injection command signal Vj is generated.
It can be configured by The program for operating the microcomputer 10A includes a check program for checking whether or not the microcomputer is operating normally by a known method. In a state where the microcomputer is operating normally, , The microcomputer generates the high level switching signal Ve,
This switching signal Ve is given to the control terminal of the switching circuit 12A. The switching circuit 12A supplies a trigger signal to the control terminal of the switch circuit 12B from the microcomputer 10A side while the injection command signal Vj 'is being generated when the switching signal Ve is supplied, to make the switch circuit 12B conductive. . The switching circuit 12A is also switched during the period when the injection command signal Vj given from the rectangular wave signal generating circuit 11B side is generated when the supply of the switching signal Ve is stopped due to the abnormal operation of the microcomputer. A trigger signal is applied to the control terminal of the circuit 12B. The switch circuit 12B is turned on while the trigger signal is being supplied from the switch circuit 12A, so that a drive current is supplied from the power supply circuit 14 to the drive coil 13a of the injector 13. The injector 13 opens its 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).

In the apparatus of FIG. 1, when the microcomputer 10A is operating normally, a drive current is given to the injector 13 while the microcomputer is generating the soft control injection command signal Vj '.
The injection time of fuel is controlled by the microcomputer 10A. When the microcomputer 10A does not operate normally because the power is not established when the engine is started, or when the microcomputer 10A does not operate normally due to some cause while the engine is operating, the microcomputer 10A outputs the switching signal Ve. In order to stop the output of the above, the switching circuit 12A gives the trigger signal to the switch circuit 12B during the period when the hardware control injection command signal generator 11 is generating the injection command signal Vj. Therefore, in an emergency when the microcomputer does not operate normally, the injection time of fuel is controlled by the hard control injection command signal generator 11. Since the time width of the injection command signal for hardware control becomes narrower as the temperature rises, the fuel becomes rich when the air temperature is high, and the fuel becomes lean when the air temperature is low. Can be prevented.

FIG. 2 shows a concrete example of the configuration of the hard control injection command signal generator 11 used in the embodiment of the present invention. In FIG. 2, 1 is a rotor 101 and a signal generator 102.
It is a signal generator consisting of and. The rotor 101 has a reluctor 101a provided on the outer circumference of an iron rotating body, and is attached to the rotating shaft of the engine. A flywheel of a flywheel magnet rotor attached to the engine can be used as the rotating body that constitutes this rotor.

The signal emitting electron 102 is a known one having 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 reluctor 101a emits a signal 1
No. 02 iron core, the signal coil 10 is caused by a change in the magnetic flux that occurs when the magnetic core portion starts facing the magnetic pole portion and when the facing ends.
Pulsed signals Vs1 and Vs2 are generated at 2a.

The reluctor provided on the rotor 101 may be any one as long as it causes a magnetic flux change in the signal-generating electrons at one end and the other end in the circumferential direction, and may be a recess provided on the outer peripheral portion of the rotating body.

Further, the signal generator 1 does not necessarily need to use the above-mentioned signal emitting electrons, and a semiconductor magnetic detection element such as a Hall IC may be used to detect the magnetic flux change caused by the reluctor. You can also use it.

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

The above timing signal Vs1 is input to the trigger terminal TRG of the monostable multivibrator 5 through the diode 4. Monostable multivibrator 5
External capacitor / resistor connection terminal Tn and ground terminal GN
The signal width determination circuit 6 is connected between the signal generator D and the D, and the monostable multivibrator 5 and the signal width determination circuit 6 constitute a rectangular wave signal generation circuit 11B. This rectangular wave signal generation circuit generates a rectangular wave signal having a signal width tj determined by the time constant of the signal width determination circuit 6 as the hard control injection command signal Vj every time the timing signal Vt is applied. The signal width tj becomes the fuel injection time.

The signal width determination circuit 6 has a basic injection time setting element 6A for giving a basic injection time corresponding to the minimum value of the required injection time of the engine with respect to the air temperature, and a characteristic at the time of starting having a characteristic that impedance changes according to temperature. The injection time adjustment element 6B, the steady operation injection time adjustment element 6C having a characteristic that impedance changes with temperature, and the startup injection time adjustment element 6B are invalidated when the rotation speed of the internal combustion engine reaches a set value. It comprises a switch means S for switching and a capacitor C, and the capacitor C is connected between the terminals Tn and GND.

The basic injection time setting element 6A is a fixed resistor R
When the signal width of the rectangular wave signal output from the monostable multivibrator 5 is set only by the fixed resistor Ro and the capacitor C, the signal width is the minimum value of the required injection time of the engine with respect to the air temperature ( (Injection time required to obtain the specified air-fuel ratio when the air temperature is sufficiently high)
The resistance value of the fixed resistor Ro is set so as to be equal to the basic injection time to (see FIG. 3) corresponding to

The illustrated starting injection time adjusting element 6B is a temperature sensitive resistance element Rt1 such as a thermistor having a negative temperature coefficient.
And a fixed resistor R connected in parallel with this temperature-sensitive resistance element
This adjusting element 6 is composed of a resistance circuit composed of 1 and
Switches S are connected to both ends of B. Adjustment element 6
Since B includes the temperature-sensitive resistance element Rt1, it has a characteristic (temperature characteristic) that its resistance value changes with a change in temperature. The temperature characteristics (the resistance value and the rate of change with respect to the temperature thereof) of the adjusting element 6B can be appropriately adjusted by changing the resistance value and temperature coefficient of the temperature sensitive resistance element Rt1 and the resistance value of the fixed resistor R1.

The switch S is provided for disabling the starting injection time adjusting element 6B after the start of the engine is completed, and is composed of a semiconductor switch element such as a transistor. The switch S holds the conduction state while the trigger signal is given, and becomes the cutoff state when the trigger signal is removed.

In this example, the fixed resistor R1 is connected in parallel to the temperature sensitive resistance element Rt1, but the adjustment element 6B is formed by a series circuit of the temperature sensitive resistance element and the fixed resistor, and The adjustment element 6 is composed of a fixed resistor connected in parallel at both ends of a series circuit of the temperature resistance element and the fixed resistor.
It is also possible to configure B. Further, when the resistance value and temperature characteristic of the temperature sensitive resistance element itself match the resistance value and temperature characteristic required for the adjusting element 6B, the adjusting element 6B may be configured by a single temperature sensitive resistance element. . Further, by connecting a plurality of temperature-sensitive resistance elements having different temperature characteristics in series or in parallel, or by combining a plurality of temperature-sensitive resistance elements and fixed resistors in series or in parallel, the adjusting element 6B having a desired temperature characteristic. May be configured. In summary, the adjustment element 6B has at least one
A resistance circuit including one temperature sensitive resistance element and having a predetermined temperature characteristic may be used.

Injecting time adjusting element 6C during steady operation shown in the figure
Is composed of a resistance circuit including a temperature-sensitive resistance element Rt2 and a fixed resistor R2 connected in parallel with the temperature-sensitive resistance element. The adjusting element 6C may be a resistance circuit having a desired temperature characteristic, and the same modification as the adjusting element 6B can be considered.

In this embodiment, the basic injection time setting element 6A is used.
And the adjusting elements 6B and 6C, the product of the combined resistance value and the capacitance of the capacitor C (time constant of the signal width determining circuit) determines the signal width of the injection command signal Vj at each temperature (mixed with fuel). Adjusting element 6B so that the signal width Vj in the temperature of the air) is approximately equal to the injection time at the start of the engine.
The resistance value and temperature coefficient of the setting element 6A, adjusting element 6C
It is set to an appropriate value in consideration of the resistance value and the temperature coefficient.

Further, in the state where the signal width of the injection command signal Vj is determined by the time constant determined by the product of the combined resistance value of the setting element 6A and the adjustment element 6C and the electrostatic capacitance of the capacitor C,
The resistance value and the temperature coefficient of the adjusting element 6C are set to appropriate values in consideration of the resistance value of the resistor Ro so that the signal width at each temperature is almost equal to the injection time during steady operation at each temperature. Keep it.

The output of the signal generator 1 is given to the rotation speed detection circuit 7, which gives a trigger signal to the switch S when it is detected that the rotation speed of the engine has reached a set value. . As a result, the switch S is turned on to short-circuit the starting negative injection time adjusting element 6B and disable the adjusting element. When the engine speed is above the set value,
Since the rotation speed detection circuit 7 continues to generate the trigger signal, the switch S keeps the conduction state and continues to disable the adjusting element 6B. The set value of the rotation speed at which the rotation speed detection circuit 7 gives the trigger signal to the switch S is set equal to the rotation speed at the time when the start of the engine is completed.

In the above embodiment, since the switch S is opened when the engine is started, the signal width of the injection command signal Vj output by the monostable multivibrator 5 is determined by the combined resistance value of the adjusting elements 6A to 6C and the capacitor C. It depends on the electrostatic capacity of. At this time, the signal width of the injection command signal Vj becomes wider than that in the steady operation, so that the injection time becomes longer and the startup amount increase control is performed.

When the engine start is completed and the engine speed reaches the set value, the switch S is closed to invalidate the starting injection time adjusting element 6B, so that the monostable multivibrator 5 is used.
The signal width of the injection command signal Vj that is output by is determined by the combined resistance value of the steady operation injection time adjustment element 6C and the basic injection time setting element 6A and the capacitance of the capacitor C. Therefore, the signal width of the injection command signal Vj at the time of steady operation becomes narrower than that at the time of start, and an injection time suitable for steady operation can be obtained. Since the temperature coefficient of the temperature characteristic of the injection time adjusting element 6C during steady operation is negative, the signal width of the injection command signal during steady operation becomes shorter as the intake air temperature of the signal width determination circuit rises. Therefore, as shown by the solid line in FIG. 3, the injection time during steady operation becomes shorter as the temperature rises.

In the above embodiment, the signal width determining circuit 6
The temperature sensor of the temperature of the air (intake) mixed with fuel,
Alternatively, it is arranged at a position where the temperature of a specific portion (for example, the temperature near the engine) having a certain correlation with the temperature of the air mixed with the fuel can be detected.

FIG. 4 collectively shows the relationship between the injection time tj and the temperature when the injector is driven by using the hard control injection command signal generator 11 of the above embodiment.
The characteristic shown by the solid line in the figure shows the characteristic at the time of starting,
The characteristic indicated by the chain line shows the characteristic during steady operation.

FIG. 5 shows the time course of the injection time tj when the injector is driven by using the hard control injection command signal generator 11 of the above embodiment to start the engine. to indicates the start operation start time, and t1
Indicates the start completion time. In FIG. 5, the characteristic indicated by the solid line shows the characteristic when the temperature of the air mixed with the fuel is low, and the characteristic indicated by the chain line shows the characteristic when the temperature of the air mixed with the fuel is high.

In the above example, the characteristic that the injection time during steady operation shortens almost linearly as the temperature rises is obtained, but when the temperature characteristic of the injection time adjusting element 6C during steady operation is non-linear. In the case where the steady-state injection time adjusting element 6C is composed of a single thermistor in the above embodiment (for example), the characteristics of the injection time with respect to temperature are non-linear as shown in FIG.

In the above embodiment, all the signal width adjusting elements are connected in series with the capacitor C, but at least a part of the signal width adjusting elements may be connected in parallel with the capacitor C. . For example, as shown in FIG.
Temperature-sensitive resistance element R that constitutes the constant injection time adjustment element 6A
You may make it connect t2 to the capacitor C in parallel.
In this case, it is necessary to use the temperature sensitive resistance element Rt2 having a positive temperature coefficient.

In the example of FIG. 7 as well, in order to adjust the temperature characteristic of the steady-state injection time adjusting element 6C, the temperature-sensitive resistance element Rt2
A fixed resistor can be connected in series or in parallel with.

FIG. 8 shows still another embodiment of the present invention. In this embodiment, a resistor R3 is further connected to both ends of a parallel circuit of a fixed resistor R1 and a temperature sensitive resistance element Rt1 via a switch S. Are connected. In this example, the temperature sensitive resistance element Rt1 having a negative temperature coefficient and the fixed resistor R1 constitute a starting injection time adjusting element, and the temperature sensitive resistance element Rt1 and the fixed resistors R1 and R3 make an injection during steady operation. A time adjustment element is configured.

Since the switch S is opened at the time of starting the engine, the injection time at the time of starting is determined by the parallel circuit of the temperature sensitive resistance element Rt1 and the fixed resistor R1. During normal operation of the engine, the switch S is closed, and the resistance R3 is further connected in parallel to the parallel circuit of the temperature-sensitive resistance element Rt1 and the fixed resistor R1, so that the injection time is a value suitable for steady operation (starting increase control). Value shorter than time).

In each of the above-described embodiments, the monostable multivibrator is used as the rectangular wave signal generating circuit, but a rectangular wave signal generating circuit having another configuration can be used. FIG. 9 shows an embodiment in which a rectangular wave signal generation circuit is configured without using a monostable multivibrator. In this embodiment,
One end of the capacitor C is grounded, and between the non-grounded side terminal of the capacitor C and the power supply terminal E, the basic injection time setting element 6A, the starting injection time adjusting element 6B, and the steady state which are configured similarly to the example of FIG. The in-operation injection time adjusting element 6C is connected in series. A transistor T is placed on both ends of the capacitor C.
The collector-emitter circuit of r1 is connected in parallel, and the diode D1 is connected to the base of the transistor Tr1 through the resistor R4.
Is connected to the cathode. The signal coil 102a of the signal generator is connected between the anode of the diode D1 and the ground. Further, a voltage dividing circuit 6D composed of a series circuit of resistors R5 and R6 is connected between the power supply terminal E and the ground, and the resistor R6
A reference voltage Vr can be obtained across both ends of the. The reference voltage Vr is input to the non-inverting input terminal of the comparator CP, and the voltage Vc across the capacitor C is input to the inverting input terminal of the comparator CP. Although not shown, the output of the signal coil 102a is input to the rotation speed detection circuit as in the example shown in FIG. 2, and the switch S is controlled by the rotation speed detection circuit. The temperature sensitive resistance elements Rt1 and Rt2 are thermistors having a negative temperature coefficient.

The basic injection time setting element 6A, the starting injection time adjusting element 6B, the steady operation injection time adjusting element 6C, the capacitor C, and the voltage dividing circuit 6D constitute a signal width determining circuit 6.

In the embodiment shown in FIG. 9, the signal coil 102a has the signal voltages Vs1 and Vs2 as shown in FIG.
To occur. Positive signal voltage (timing signal) Vs1
Is a transistor T through a diode D1 and a resistor R4.
The transistor Tr1 is supplied to the base of r1 and conducts while the signal voltage Vs1 is generated to discharge the electric charge of the capacitor C. Immediately after the transistor Tr1 is cut off, the capacitor C is charged to the polarity shown through the basic injection time setting element 6A, the starting injection time adjusting element 6B, and the steady operation injection time adjusting element 6C. The voltage Vc across the capacitor C rises with a predetermined slope as shown in FIG.
It returns to zero when the signal voltage Vs1 is generated and the transistor Tr1 becomes conductive. As shown in FIG. 10 (C) or (D), the comparator CP outputs a high-level rectangular wave signal as the injection command signal Vj while the reference voltage exceeds the voltage Vc across the capacitor C. When the engine is started, the capacitor C is charged through the series circuit of the setting means 6A and the adjusting means 6B and 6C, so that the gradient of the voltage across the capacitor C becomes small as shown in FIG. 10 (B). Therefore, as shown in FIG. 10D, the injection command signal Vj
Signal width becomes wider, and the increase control at the time of starting is performed. The signal width of the injection command signal Vj at the time of starting becomes wide when the temperature is low and becomes narrow when the temperature is high.

When the engine start is completed and the rotation speed reaches the set value, and the switch S is closed, the starting injection time adjusting means 6
Since B is short-circuited and the capacitor C is charged through the basic injection time setting element 6A and the steady operation injection time adjusting element 6C, as shown by the solid line in FIG. The slope of the voltage becomes steep. Therefore, as shown in FIG. 10C, the injection command signal Vj
The signal width of is shortened, and the injection time is switched to a length suitable for steady operation. During steady operation, the signal width of the injection command signal Vj becomes wide when the temperature is low, and the signal width of the injection command signal Vj becomes narrow when the temperature is high.

In the example shown in FIG. 9, the starting injection time adjusting element 6B and the steady operation injection time adjusting element 6C are provided on the charging circuit side of the capacitor C, but one or both of them are provided on the voltage dividing circuit 6D side. It may be provided in the. For example, as shown in FIG. 11, the temperature sensitive resistance element Rt1 is connected to the switch S '.
The resistor R5 and the temperature-sensitive resistance element Rt1 may be connected in parallel to both ends of the resistor R5 via the resistor R5 to form the starting injection time adjusting element 6B. In this case, it is necessary to use the temperature sensitive resistance element Rt1 having a positive temperature coefficient. Further, the switch S ′ is controlled so as to be closed when the engine is started and opened when the start is completed and the rotation speed reaches a set value.

In the example shown in FIG. 11, since the temperature sensitive resistance element Rt1 is connected in parallel with the resistance R5 when the engine is started, the value of the reference voltage Vr becomes large. Therefore, the signal width of the injection command signal Vj becomes wider, and the increase control at the start is performed. At this time, the level of the reference voltage Vr becomes higher as the temperature rises, so that the signal width of the injection command signal Vj at the time of starting becomes shorter as the intake air temperature rises.

Since the switch S'is turned off during the steady operation, the reference voltage Vr becomes higher than the starting level and the injection command signal Vj becomes shorter. Similar to the example of FIG.
The signal width of the injection command signal Vj during steady operation becomes shorter as the temperature rises.

In the example shown in FIG. 11, instead of connecting the temperature sensitive resistance element Rt1 having a positive temperature coefficient across the resistor R5, a temperature sensitive resistance element having a negative temperature coefficient in series with the resistance R6. And a switch S that is closed when the number of rotations reaches a set value, is connected to both ends of the temperature sensitive resistance element to obtain a voltage obtained across the series circuit of the temperature sensitive resistance element and the resistor R6. The reference voltage Vr may be input to the comparator CP.

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

In each of the above embodiments, the temperature sensitive resistance element is used as the temperature sensitive element, but the temperature sensitive element may be any element having a characteristic that the impedance changes according to the ambient temperature, for example, the capacitance. It is also possible to use, as the temperature sensitive element, a capacitor having a characteristic that changes according to the ambient temperature.

[0068]

As described above, according to the present invention, the rectangular wave signal in which the signal width is narrowed as the intake air temperature is increased by giving the temperature characteristic to the adjusting element of the signal width determining circuit that determines the signal width. Since this rectangular wave signal is used as the injection command signal for hardware control, the air-fuel ratio can be adjusted to a proper state with respect to the change in intake air temperature even when the engine is operated with the microcomputer not operating normally. There is an advantage that the operation of the engine can be carried out without any trouble.

[Brief description of drawings]

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

FIG. 2 is a circuit diagram showing a specific configuration example of a hard control injection command signal generation section used in the apparatus of FIG.

FIG. 3 is a diagram showing the relationship between injection time and temperature when the injector is driven by a signal generated by the signal generator of FIG. 2 during steady operation of the engine.

4 is a diagram showing the relationship between the injection time and the temperature at the time of starting and steady operation when the injector is driven by the output of the signal generator of FIG.

5 is a diagram showing a temporal change of an injection time when the injector is driven by the output of the signal generator of FIG. 2 to start the engine.

FIG. 6 is a diagram showing an injection time vs. temperature characteristic obtained when the injection time adjusting element at the time of steady operation in the signal generating unit of FIG. 2 is composed of only a thermistor.

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

FIG. 8 is a circuit diagram showing another modification of the hard control injection command signal generator used in the present invention.

FIG. 9 is a circuit diagram showing still another configuration example of the injection command signal generator for hardware control used in the present invention.

FIG. 10 is a waveform diagram showing signal waveforms of respective parts of FIG.

FIG. 11 is a circuit diagram showing still another configuration example of the injection command signal generator for hardware control used in the present invention.

FIG. 12 is a circuit diagram showing a configuration example of a hard control injection command signal generating section used in an already proposed injector driving device.

13 is a diagram showing the relationship between the injection time and the temperature at the time of starting when the injector is driven by the output of the hardware control injection command signal generating unit of FIG.

14 is a diagram showing the relationship between the injection time and the temperature during steady operation and the relationship between the required injection time and the temperature of the engine when the injector is driven by the output of the signal generator of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Signal generator 5 Monostable multivibrator 6 Signal width determination circuit 6A Basic injection time setting element 6B Startup injection time adjustment element 6C Steady operation injection time adjustment element 6D Reference signal generation circuit 10 Soft control injection command signal generation section 11 Injection control signal generator for hardware control 11A Signal generation means 11B Rectangular wave signal generation circuit 12 Injector drive circuit 13 Injectors Ro to R6 Fixed resistors Rt1, Rt2 Temperature sensitive resistance element C Capacitor

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[Procedure amendment]

[Submission date] December 10, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction content]

[0008] Control device of the already proposed, as a variety of soft control injection command signal a signal having a time width by calculating the fuel injection time corresponding to the calculated fuel injection time according to the control condition of the microcomputer soft control injection command signal generation section that occur and hard control injection command signal generator for generating a signal having a time width corresponding to the predetermined fuel injection time as a hard control injection command signal using hardware circuitry When the microcomputer is operating normally, the drive current is supplied to the injector while the soft control injection command signal is generated, and in the emergency when the microcomputer is not operating normally, the hard control injection command signal There is provided an injector driving circuit for supplying a drive current to the injector during the occurrence.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0030

[Correction method] Change

[Correction content]

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

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0031

[Correction method] Change

[Correction content]

The injector drive circuit 12 supplies a drive current to the injector 13 while the soft control injection command signal Vj 'is generated when the microcomputer is in a state where it can operate normally, and the microcomputer operates normally. When not in the state, a circuit for supplying a drive current to the injector 13 while the hard control injection command signal Vj is generated is provided by the switching circuit 12A and the switch circuit 1
2B and can be configured. Microcomputer 10A
The program for operating the, a check program for checking whether the microcomputer is operating normally by a known method is incorporated,
When the microcomputer is operating normally,
The microcomputer generates a high level switching signal Ve, and this switching signal Ve is given to the control terminal of the switching circuit 12A. The switching circuit 12A is a switching circuit 12 while the injection command signal Vj 'is generated from the microcomputer 10A side when the switching signal Ve is applied.
A trigger signal is applied to the control terminal of B to switch the switch circuit 12
Conduct B. The switching circuit 12A also receives a switching signal Ve when the microcomputer does not operate normally.
Of the rectangular wave signal generation circuit 11B when the supply of
A trigger signal is given to the control terminal of the switch circuit 12B during the period when the injection command signal Vj given from the side is generated.
The switch circuit 12B is conductive during the period in which the trigger signal is given from the switch circuit 12A, and causes a drive current to flow from the power supply circuit 14 to the drive coil 13a of the injector 13. The injector 13 opens its 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).

Claims (3)

[Claims] 1. A soft control injection command signal generation for generating a soft control injection command signal of a time width corresponding to the calculated fuel injection time by calculating a fuel injection time according to various control conditions by a microcomputer. Section, a hardware 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 the soft control injection when the microcomputer is operating normally. An injector drive that supplies a drive current to the injector while the command signal is generated, and supplies a drive current to the injector while the hard control injection command signal is generated when the microcomputer is not operating normally And an injector drive device for an internal combustion engine, comprising: The unit has a timing signal generating means for generating a timing signal at a fuel injection position of the internal combustion engine, and a signal width determining circuit, and controls the signal width determined by the signal width determining circuit each time the timing signal is given. A rectangular wave signal generating circuit for generating a rectangular wave signal having the injection command signal for hardware control is provided, and the signal width determining circuit has a starting injection time adjusting element having a characteristic that impedance changes according to temperature, The injection time adjustment element during steady operation, which has the characteristic that impedance changes with temperature, and the injection time adjustment element during startup, which works effectively when the engine speed is less than the set value, reaches the set value. And a switch means for switching the circuit configuration of the signal width determination circuit so that the injection time adjusting element during steady operation works effectively. Sometimes the temperature characteristics of the starting injection time adjusting element and the steady operation injection time adjusting element are set so that the signal width of the rectangular wave signal generated by each of the rectangular wave signal generating circuits is shortened as the temperature rises. An injector drive device for an internal combustion engine, comprising: 2. The injector for an internal combustion engine according to claim 1, wherein the starting injection time adjusting element and the steady operation injection time adjusting element are composed of a resistance circuit including a temperature sensitive resistance element whose resistance value changes with temperature. Drive. 3. The startup injection time adjusting element and the steady operation injection time adjusting element are connected in series with each other, and the switch means is connected in parallel to both ends of the startup injection time adjusting element, The injector drive device for an internal combustion engine according to claim 2, wherein when the rotational speed reaches a set value, the switch means is turned on to short-circuit the startup injection time adjusting element.