JP2000320394A - Control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To electrically connect an ECU to the solenoid of a solenoid valve with a single wire. SOLUTION: An ECU 5 for controlling drive current to a solenoid of solenoid valve is so constructed that the terminal that is connected to one end of a main switch 7 is directed outside the ECU 5 as the only solenoid-connection terminal 5a. The ends of a solenoid 4 are connected to the free output terminal of a DC power source 10 and the solenoid-connection terminal 5a of the ECU 5 respectively. The other end of the main switch 7 is connected via a current detecting circuit 8 to the grounded circuit. A flyback current carrying circuit is interposed between the solenoid-connection terminal 5a and the output terminal of the DC power source 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an internal combustion engine for controlling the solenoid of an electromagnetic valve for an internal combustion engine such as a solenoid valve for fuel injection or an idle speed control using an electronic control unit. It is.

[0002]

2. Description of the Related Art Electromagnetic valves (injectors) for fuel injection
Also, electromagnetic valves for internal combustion engines, such as idle speed control valves (ISC valves), open and close valves using electromagnetic force generated when a current flows through a coil of a solenoid (electromagnet).

An electronic control unit (E) that centralizes control functions such as control of the ignition timing of an internal combustion engine and control of the fuel injection amount.
When the CU is provided, the control device for the electromagnetic valve is usually built in the ECU.

[0004] The injector includes an injector body having a fuel injection port at a tip thereof, a needle valve for opening and closing the injection port, and a solenoid for driving the needle valve. 1 for
And are attached to the intake pipe of the engine. Fuel is supplied from an electromagnetic pump to the inlet of the injector body.
50 KHP). The injector is
The valve is opened to inject fuel while a drive current of a certain value or more is given to the solenoid. Fuel injected from an injector into an intake pipe or the like is mixed with air to form an air-fuel mixture and is sucked into a corresponding cylinder of the engine.

[0005] In order to control the output of the engine and the exhaust gas component well, it is necessary to control the amount of fuel injected from the injector with high accuracy. Electronic control unit (EC
In U), the injection time is obtained by converting the preset optimal amount of fuel into the injection time based on information such as the engine speed, the intake air amount, the air temperature, the cooling water temperature (engine temperature), and the like. Power to the injector's solenoid for the necessary time.

[0006] The ISC valve is provided in the middle of a bypass air passage provided to bypass a main air passage provided with a throttle valve. When the ISC valve opens, the amount of air flowing in increases regardless of the opening degree of the throttle valve, and the engine speed increases.

As the ISC valve, a valve using a step motor as a drive source and a valve using a so-called on-off solenoid driven by a drive current having a pulse waveform of a constant frequency as a drive source for valve operation are used. But,
In the present invention, the latter uses an on / off solenoid as a valve operating drive source. In an ISC valve using an on / off solenoid, the opening degree changes according to the change in the on-duty ratio of the drive current.

The ECU maximizes the opening of the ISC valve when the engine is started, thereby maximizing the air flow rate in the bypass air passage to improve the startability of the engine.
The on-duty ratio of the drive current of the ISC valve is controlled so as to maintain the air flow rate in the bypass air passage at an optimum value determined by the engine coolant temperature, thereby stabilizing the idle speed immediately after the start.

During the warm-up operation, the ISC is controlled so that the idle speed of the engine is maintained at a target speed determined by the temperature of the cooling water.
By controlling the on-duty ratio of the drive current of the valve, the average flow rate of the air flowing through the ISC valve is adjusted so that the idle speed is maintained at the target value. After the warm-up operation, the ISC valve is controlled according to the load state of the internal combustion engine to prevent engine stall. Therefore, when the throttle valve is in the fully closed state, the idling speed is always kept constant with respect to load fluctuations without requiring any operation by the driver.

Normally, the ECU controls the opening of the ISC valve not only at the time of idling operation but also at the time of sudden deceleration to provide a dashpot function to prevent engine stall.

In the above-described electromagnetic valve for an internal combustion engine, when a closed valve is opened, a relatively large valve opening current Io needs to flow as a drive current to the solenoid.
After the valve is once opened, the valve can be kept open only by passing a holding current Ih smaller than the valve opening drive current to the solenoid.

In controlling an electromagnetic valve for an internal combustion engine such as an injector or an ISC valve, when the valve is opened, a drive current is continuously supplied to the solenoid for a certain period of time in order to open the valve as quickly as possible. If the drive current continues to flow, the drive current increases and a current larger than necessary flows compared to the holding current Ih. Therefore, heat generated from the solenoid and a semiconductor switch such as a transistor that causes the drive current to flow through the solenoid are generated. Heat generated in the element increases, and wasteful power is consumed.

Further, since heat generated from a semiconductor switch element such as a transistor increases, a heat sink attached to the switch element increases in size, which is an obstacle to downsizing the ECU.

In order to solve these problems, when controlling an electromagnetic valve for an internal combustion engine, the valve is opened by passing a valve-opening current and then the solenoid driving switch element is turned on / off to control the solenoid. The upper limit value Ih1 (>) in which the current has a necessary margin with respect to the holding current Ih.
Ih) and the lower limit Ih2 (<Ih).

FIG. 8 shows a configuration example of a conventional control device for an internal combustion engine for controlling an electromagnetic valve such as an injector or an ISC valve. In FIG. 8, 1 is an AC generator such as a magnet generator or an alternator driven by an internal combustion engine, 2 is a rectifier for rectifying the output of the generator 1, and a constant value of the DC voltage output from the rectifier. A rectifier having a voltage regulator having a voltage regulator limited to the following: 3 is a battery charged by the output of the rectifier 2 having a voltage regulator; 4 is a solenoid of an electromagnetic valve for an internal combustion engine such as an injector or an ISC valve; ′ Is an electronic control unit (ECU) that controls the electromagnetic valve 4.

The ECU 5 'is provided with a CPU 6 for generating a drive signal for instructing the solenoid 4 to be driven in accordance with a predetermined control condition. A main switch 7 for supplying a drive current to the solenoid, a current detection circuit 8 'for detecting a drive current of the solenoid 4 flowing through the main switch 7, and a drive current for maintaining the current detected by the current detection circuit 8' in a set range. Current control circuit 9 ', a diode D1 for supplying a flyback current to the solenoid 4, and a voltage (3 V or 5 V) suitable for driving the drive current control circuit 9' with the output voltage of the rectifier 2 as an input. ) Is provided. In this example, a flyback current supply circuit is constituted by a circuit consisting of a solenoid 4, a main switch 7, a current detection circuit 8 ', a diode D1, and a solenoid 4.

The CPU reads various kinds of information such as crankshaft angle information, intake pipe pressure information, and engine temperature information necessary for controlling the engine from the sensor, and executes a program written in a ROM (not shown). Detection of crankshaft rotation angle, ignition timing control, fuel injection control, I
To perform various calculations for controlling the SC valve, etc., and to control the ignition signal, the ignition signal for operating the ignition device, the injection command signal for injecting fuel from the injector, or the ISC valve. And the like.

The main switch 7 is a main switch for turning on and off the drive current of the solenoid 4, and the main switch shown in the figure is an N switch having a collector connected to one end of the solenoid 4.
The transistor 6 comprises a PN transistor TR1 and a resistor R1 having one end connected to the base of the transistor.
d is given.

The current detection circuit 8 'includes a transistor T
A current detecting resistor r connected between the emitter of R1 and ground.
1, a current detection signal (voltage signal) proportional to the drive current of the solenoid flowing between the collector and the emitter of the transistor TR1 is generated at both ends of the resistor r1.

The drive current control circuit 9 'includes a PNP transistor TR2 which constitutes a sub-switch for controlling the drive current. The emitter of the transistor TR2 is connected to the positive output terminal of the rectifier 2, and the collector is connected to the solenoid coil 4. Each is connected to the end. An NPN transistor T having an emitter grounded is provided at the base of the transistor TR2.
The collector of R3 is connected through a resistor R2, and the base of the transistor TR3 is connected through a resistor R3 to the output terminal of the comparator CP. The output terminal of the comparator CP is also connected to the non-ground side output terminal of the power supply circuit 11 through a resistor R4, and a feedback resistor R5 is connected between the non-inverting input terminal and the output terminal of the comparator CP.

A voltage dividing circuit composed of a series circuit of resistors R6 and R7 is connected between the output terminals of the power supply circuit 11,
The reference voltage obtained between the connection point of R6 and R7 and the ground is input to the non-inverting input terminal of the comparator CP. Comparator CP
The current detection signal obtained from the current detection circuit 8 'is input to the inverting input terminal.

The collector of a PNP transistor TR4 whose emitter is connected to the output terminal of the power supply circuit 11 is connected to the non-inverting input terminal of the comparator CP.
Is connected to the output terminal of the timer unit TM to which the drive signal Vd is input from the CPU 6. The timer unit TM is provided to prevent the operation of limiting the drive current of the solenoid from starting to drive the solenoid until a predetermined time Tp has elapsed. In the timer unit TM, when the CPU does not generate the drive signal Vd, a base current flows through the transistor TR4 to make the transistor TR4 conductive.
When the CPU generates a drive signal, the timer unit TM starts a timed operation. The timer unit TM terminates the timed operation when a predetermined time Tp has elapsed after the generation of the drive signal, cuts off the base current of the transistor TR4, and turns off the transistor.

The transistor TR4 constitutes a voltage-dividing resistor short-circuit switch for short-circuiting the resistor R6 on the upper side of the resistor voltage dividing circuit to increase the reference voltage while the timer unit TM performs the timed operation.

The timer unit TM includes the transistor TR4
While the base current is flowing through the transistor TR4, the transistor TR4 conducts and shorts the resistor R6. Therefore, the reference voltage Vr input to the non-inverting input terminal of the comparator CP has a high initial value that is substantially equal to the output voltage of the power supply circuit 11 until the fixed time Tp elapses after the generation of the drive signal Vd. Value Vro
Is shown. The initial value of the reference voltage Vr is set sufficiently higher than the maximum value of the current detection signal Vi.
When a certain time Tp elapses after the generation of the drive signal Vd,
The reference voltage input to the non-inverting input terminal of the comparator CP decreases to a value (first value) Vr1 obtained by dividing the output voltage of the power supply circuit 11 by the resistors R6 and R7. When the current detection signal Vi generated by the current detection circuit 8 'exceeds the reference voltage Vr, the potential of the output terminal of the comparator CP1 drops to substantially the ground potential. At this time, the decrease in the potential of the output terminal of the comparator is caused by the resistance R5.
Is fed back to the non-inverting input terminal of the comparator CP, the reference voltage Vr becomes the second value Vr lower than the first value Vr1.
It drops to r2. The first value Vr1 of the reference voltage Vr corresponds to the upper limit value Ih1 of the change range of the holding current Ih of the solenoid,
The second value Vr2 of the reference voltage corresponds to the lower limit value Ih2 of the change range of the holding current Ih of the solenoid.

FIG. 9 is a timing chart showing the operation of the control device for an internal combustion engine shown in FIG. When the condition for opening the electromagnetic valve is satisfied, the CPU 6 generates the drive signal Vd as shown in FIG. When the drive signal Vd is generated, as shown in FIG.
Is turned on. On the other hand, the transistor TR4 is on before the drive signal Vd is generated, and the drive signal Vd
Until a predetermined time Tp elapses after the occurrence of d, the transistor TR4 is kept on, and the value of the reference voltage Vr input to the non-inverting input terminal of the comparator CP is set to the high initial value Vro. . At this time, since the potential of the output terminal of the comparator CP is at a high level, the transistor TR3
Is in the ON state, and the transistor TR2 is in the ON state. Therefore, when the drive signal Vd is generated, a drive current IL flows from the power supply constituted by the AC generator 1, the rectifier 2 and the battery 3 to the solenoid 4 through the transistors TR2 and TR1. When the reference voltage indicates a high initial value Vro, the potential of the output terminal of the comparator CP is kept at a high level because the current detection signal Vi cannot exceed the reference voltage. Therefore, as shown in FIG. 9 (F), the drive current IL increases according to a time constant determined by the inductance of the solenoid coil. FIG.
As shown in (D), the current detection signal Vi has a waveform similar to the waveform of the current (FIG. 9F) flowing through the solenoid 4.

When the drive current IL flowing through the solenoid 4 reaches a predetermined level Io, the valve starts displacing toward the open position, as shown in FIG. Become open.

After the generation of the drive signal Vd, a predetermined time T
When p elapses, the transistor TR4 is turned off. The drive current flowing immediately before the transistor TR4 is turned off becomes the peak value Ip of the valve opening current.

When the transistor TR4 is turned off,
Since the reference voltage Vr decreases to the second value Vr2, the potential of the output terminal of the comparator CP becomes almost the ground potential, and the transistor TR3 is turned off. As a result, the transistor TR2 is turned off, and the solenoid is disconnected from the power supply, so that the current IL flowing through the solenoid 4 rapidly decreases from the peak value Ip. At this time, a flyback voltage having a polarity that causes the current that has been flowing to continue to flow is induced in the solenoid coil, and the flyback voltage causes the solenoid 4-transistor TR1−resistance r1−
The flyback current IF (FIG. 9G) flows through the flyback current supply circuit of the diode D1-solenoid 4.

When the flyback current flowing through the solenoid 4 attenuates and reaches the lower limit value Ih2 of the change range of the holding current and the current detection signal Vi reaches the second value Vr2 of the reference voltage, the output terminal of the comparator CP Since the potential becomes high, the transistors TR3 and TR2 are turned on, and a drive current is supplied from the power supply to the solenoid 4. When the potential of the output terminal of the comparator CP becomes high, the reference voltage rises to the first value Vr1.

When the current detection signal Vi is equal to the first value V of the reference voltage,
A drive current is supplied from the power supply to the solenoid 4 until the current reaches r1. When the current flowing through the solenoid 4 reaches the upper limit value Ih1 of the change range of the holding current and the current detection signal Vi becomes equal to or more than the first value Vr1 of the reference voltage, the output terminal of the comparator CP becomes the ground potential. TR3 and TR
2 turns off.

By repeating these operations, the transistor TR2 turns on and off as shown in FIG.
The holding current flowing through the solenoid 4 changes between the upper limit value Ih1 and the lower limit value Ih2 as shown in FIG.

When the CPU stops generating the drive signal Vd, the transistor TR1 is turned off and the solenoid 4 is turned off in order to cut off both the current supply circuit for the drive current IL and the current supply circuit for the flyback current IF supplied from the power supply. The flowing current is instantaneously cut off, becomes smaller than the lower limit value Ih2 of the holding current, and the valve is immediately closed.

[0033]

As shown in FIG. 8,
In a conventional control device for an internal combustion engine that controls an electromagnetic valve using an ECU, since the solenoid is grounded via the ECU, it is necessary to connect the ECU and the solenoid with two wires. Therefore, the number of lead wires of the main wire harness on the internal combustion engine side and the number of lead wires of the wire harness on the ECU side or the number of terminals of the coupler increase, and this has a problem that the miniaturization of the device is hindered. .

An object of the present invention is to make it possible to connect between the ECU and the solenoid by one wiring, thereby reducing the number of lead wires of the wire harness or the number of terminals of the coupler.
An object of the present invention is to provide a control device for an internal combustion engine, which can reduce the size of the device.

[0035]

According to the present invention, there is provided an ECU which controls a solenoid of an electromagnetic valve for an internal combustion engine, and has one output terminal grounded and the other output terminal connected to a non-grounded power supply terminal of the ECU. The present invention relates to a control device for an internal combustion engine including a connected DC power supply.

The ECU includes a CPU for generating a drive signal for instructing the solenoid to be driven in accordance with a predetermined control condition, and is turned on when a drive signal is supplied from the CPU to switch from the DC power supply to the solenoid. And a drive current control circuit that controls the drive current so as to keep the current detected by the current detection circuit within a set range. A flyback current supply circuit for supplying a flyback current to the solenoid with a flyback voltage induced in the solenoid when the main switch is turned off.

In the present invention, the terminal connected to one end of the main switch of the ECU is led out from the ECU as the sole solenoid connection terminal of the ECU. One end of the solenoid is connected to the other output terminal of the DC power supply, the other end is connected to a solenoid connection terminal, and the other end of the main switch is connected to a ground circuit through a current detection circuit. The flyback current supply circuit is provided between the solenoid connection terminal and the other output terminal of the DC power supply.

With the above configuration, the ECU and the solenoid can be connected by one wire, so that the number of lead wires of the wire harness or the number of terminals of the coupler can be reduced, and the size of the device can be reduced. Can be planned.

The current detection circuit includes a current detection resistor connected between the other end of the main switch and the ground circuit, and an integration capacitor charged through the current limit resistor with a voltage across the current detection resistor. And a circuit that outputs the voltage across the integrating capacitor as a current detection signal.

In this case, the drive current control circuit controls the drive signal supplied from the CPU to the main switch so as to keep the current detected by the voltage (current detection signal) across the integrating capacitor of the current detection circuit within a predetermined range. It is constituted by a circuit that is turned on and off at a duty ratio of.

According to a preferred embodiment of the present invention, the drive current control circuit comprises a series circuit of an upper resistor and a lower resistor connected between the output terminals of the constant voltage power supply circuit. A resistor voltage dividing circuit for generating a reference voltage,
The reference voltage is input to the non-inverting input terminal, the current detection signal is input to the inverting input terminal, and the output terminal is connected to the drive signal input terminal of the main switch. A comparator for preventing supply of a drive signal to the main switch when the voltage becomes equal to or higher than a voltage input to the terminal, a feedback resistor connected between an output terminal of the comparator and a non-inverting input terminal, and a CPU comprising: A timer unit that starts timed operation when a drive signal is generated, and a reference voltage is input to the inverting input terminal of the comparator by short-circuiting the resistor on the upper side of the resistance voltage dividing circuit at least while the timer unit is performing timed operation And a voltage dividing resistor short-circuit switch for raising the current detection signal to a value higher than the maximum value of the current detection signal. In this case, the charging and discharging of the integrating capacitor is performed so that the voltage across the integrating capacitor becomes substantially equal to the value corresponding to the lower limit of the setting range of the driving current when the driving current of the solenoid reaches the lower limit of the setting range. Set a constant.

In the present invention, an output short-circuit switch of the current detection circuit for short-circuiting between the output terminals of the current detection circuit at least while the timer unit is performing the timed operation is provided, or at least the timer unit is operated for the timed operation. A current detection circuit input short-circuit switch that short-circuits between input terminals of the current detection circuit during the operation.

According to the present invention, a flyback current is supplied between one end of the main switch and the other output terminal of the DC power supply and is turned on when a flyback voltage is induced to flow a flyback current. It is preferable that the switch constitutes the flyback current flow circuit. Also, the flyback current supply switch is allowed to be turned on when the CPU generates a drive signal, and C
It is preferable to provide a switch control circuit for controlling the flyback current supply switch such that the flyback current supply switch is forcibly turned off when the PU stops generating the drive signal.

[0044]

FIG. 1 shows an example of the configuration of a control device for an internal combustion engine according to the present invention. In FIG. 1, the same parts as those of the conventional example shown in FIG. Is attached.

In FIG. 1, 1 is an AC generator such as a magnet generator or an alternator driven by an internal combustion engine, and 2 is a voltage for rectifying the output of the generator 1 and outputting a DC voltage limited to a set value or less. A rectifier 3 with an adjusting function, 3 is a battery charged by the output of the rectifier 2 with a voltage adjusting function, 4 is a solenoid of an electromagnetic valve, 5 is an ECU (Electronic Control Unit), and an AC generator 1 and a rectifier 2 with a voltage adjusting function The DC power supply 10 is constituted by the battery 3 and the battery 3.
One output terminal (the negative output terminal of the rectifier 2) of the DC power supply 10 is grounded, and the other output terminal (the positive output terminal of the rectifier 2) is connected to the non-grounded power terminal of the ECU.

Although the battery 3 is provided in the DC power supply 10 in the illustrated example, the battery 3 may not be mounted in some cases.

The ECU 5 includes a CPU 6 for generating a drive signal for instructing the solenoid 4 to be driven in accordance with predetermined control conditions. A main switch 7 for supplying a drive current to the solenoid 4;
A current detection circuit 8 for detecting a drive current of the solenoid 4 flowing through the solenoid 4; a drive current control circuit 9 for controlling the drive current of the solenoid 4 so as to keep the current detected by the current detection circuit 8 within a set range; A flyback current supply circuit 12 for supplying a flyback current;
The power supply circuit 11 that outputs a voltage (3 V or 5 V) suitable for driving the drive current control circuit 9 or the like with the output voltage of the power supply as an input, and the flyback current conduction switch 12 is turned on when the CPU 6 generates a drive signal A switch control circuit 14 that allows the flyback current flow switch 12 to be turned off when the CPU 6 stops generating the drive signal Vd. It has.

The CPU 6 reads various information such as crankshaft angle information, intake pipe pressure information, and engine temperature information necessary for controlling the engine from sensors, detects the crankshaft rotation angle, and controls the ignition timing. , Performs calculations for performing various controls such as fuel injection control and ISC valve control,
It generates an ignition signal for operating the ignition device, an injection command signal for instructing the injector to inject fuel, a control signal for controlling the ISC valve, and the like.

The main switch 7 is a main switch for turning on and off the drive current of the solenoid 4. The illustrated main switch 7 is an NPN transistor having a collector connected to one end of the solenoid 4, as in the example shown in FIG. TR1
And a resistor R having one end connected to the base of the transistor.
The drive signal Vd is supplied from the CPU 6 to the base of the transistor TR1 through the resistors R10 and R1.

The current detection circuit 8 includes a current detection resistor r1 connected between the emitter of the transistor TR1 and the ground,
The voltage at both ends of the current detecting resistor r1 is used as the current limiting resistor r.
And a current detection signal (voltage signal) proportional to the driving current of the solenoid flowing between the collector and the emitter of the transistor TR1 is generated at both ends of the integration capacitor Ci.

The drive current control circuit 9 includes an upper resistor R6 and a lower resistor R7 connected between the output terminals of the power supply circuit 11.
, A resistor voltage dividing circuit 13 for generating a reference voltage Vr across the lower resistor R7, and a comparator CP.
A feedback resistor R5 connected between the output terminal and the non-inverting input terminal of the comparator CP, and a timer unit TM for starting a timed operation when the CPU 6 generates the drive signal Vd.
At least while the timer unit TM is performing the timed operation, the resistor R6 on the upper side of the resistor voltage dividing circuit 13 is short-circuited to reduce the reference voltage Vr to a value higher than the maximum value of the voltage input to the inverting input terminal of the comparator CP. And a switch (transistor TR4) 15 for increasing the voltage dividing resistance.

The reference voltage Vr is input to the non-inverting input terminal of the comparator CP, and the current detecting signal Vi obtained at both ends of the integrating capacitor Ci of the current detecting circuit 8 is input to the inverting input terminal.
Is entered. An output terminal of the comparator CP is connected to a drive signal input terminal of the main switch 7 (in the illustrated example, a connection point between the resistors R10 and R1). The comparator CP allows the drive signal to be supplied to the main switch 7 when the voltage input to the inverting input terminal is lower than the voltage input to the non-inverting input terminal. Prevents the drive signal from being supplied to the main switch 7 when the voltage becomes higher than the voltage input to the non-inverting input terminal.

The flyback current supply switch 12 is
An emitter is connected to the output terminal on the positive polarity side of the DC power supply 10, a collector is connected to a connection point between the solenoid 4 and the main switch 7, and an NPN transistor TR5 and a resistor R11 connected between the base and collector of the transistor TR5.
It consists of

When the switch control circuit 14 is turned on, the switch 14a is provided so that the base current of the transistor TR5 is bypassed from the transistor TR5.
And a control unit 14b that controls the switch 14a to be turned on and off by using the drive signal Vd generated by the CPU 6 as an input. The control unit 14b holds the switch 14a in the off state when the drive signal Vd is given to permit the conduction of the transistor TR5, and holds the switch 14a in the on state when the drive signal Vd disappears. Blocks the conduction of TR5.

In the control device for an internal combustion engine shown in FIG. 1, when the drive current of the solenoid 4 reaches the lower limit value Ih2 of the set range, the voltage Vi across the integrating capacitor Ci becomes the lower limit value of the set range of the drive current. The time constant of charging and discharging of the integrating capacitor Ci is set so as to be substantially equal to the value corresponding to Ih2.

FIG. 2 is a timing chart showing the operation of the control device for an internal combustion engine shown in FIG. The CPU 6 generates a drive signal Vd as shown in FIG. 2A when a condition for opening the electromagnetic valve is satisfied. When the drive signal Vd is generated, the switch 14a of the switch control circuit 14 is turned off, so that the transistor TR5 is turned on as shown in FIG. Further, as shown in FIG. 2B, the transistor TR4 constituting the voltage-dividing resistor short-circuiting switch 15 is on before the drive signal Vd is generated, and for a certain time Tp after the drive signal Vd is generated.
, And the value of the reference voltage Vr input to the non-inverting input terminal of the comparator CP is set to the high initial value Vro. In this state, since the potential of the output terminal of the comparator CP is at a high level, the supply of the drive signal to the transistor TR1 is permitted. Therefore, when the drive signal Vd is generated, the transistor TR1 forming the main switch 7 is turned on as shown in FIG. 2E, and the drive current IL is supplied from the DC power supply 10 to the solenoid 4. When the reference voltage Vr indicates a high initial value Vro, the potential of the output terminal of the comparator CP is at a high level because the current detection signal Vi obtained across the integration capacitor Ci cannot exceed the reference voltage Vr. It is kept in. Therefore, the drive current IL increases according to the time constant determined by the inductance of the solenoid coil as shown in FIG. The current detection signal Vi (FIG. 2D) has a waveform similar to the waveform of the current (FIG. 2F) flowing through the solenoid 4.

When the drive current IL flowing through the solenoid 4 reaches a predetermined level Io, the valve starts displacing toward the open position as shown in FIG. Become open.

After the generation of the drive signal Vd, a predetermined time T
When p elapses, the timer unit TM ends the timed operation, and as shown in FIG.
Is turned off. The drive current flowing immediately before the transistor TR4 turns off becomes the peak value Ip of the valve opening current.
Becomes

When the transistor TR4 is turned off,
Since the reference voltage Vr decreases to the second value Vr2, the potential of the output terminal of the comparator CP becomes almost the ground potential, and the supply of the drive signal to the transistor TR1 is blocked. As a result, the transistor TR1 is turned off, and the drive current supplied from the DC power supply 10 to the solenoid 4 is cut off. Therefore, the current IL flowing through the solenoid 4 rapidly decreases from the peak value Ip. At this time, a flyback voltage having a polarity that causes the current that has been flowing to continue to flow is induced in the solenoid coil, and the flyback voltage causes the solenoid 4-transistor TR5—the positive output terminal of the rectifier 2—the solenoid 4 The flyback current IF (FIG. 2G) flows through the flyback current supply circuit of FIG.

When the flyback current flowing through the solenoid 4 attenuates and reaches the lower limit value Ih2 of the change range of the holding current,
Since the voltage obtained at both ends of the integrating capacitor Ci becomes equal to the second value Vr2 of the reference voltage set to the magnitude corresponding to the lower limit value of the holding current, the potential of the output terminal of the comparator CP becomes high. , The supply of the drive signal to the transistor TR1 is permitted. As a result, the transistor TR1 is turned on, and a drive current is supplied from the DC power supply 10 to the solenoid 4. When the potential of the output terminal of the comparator CP becomes high, the reference voltage rises to the first value Vr1.

The drive current is supplied from the power supply to the solenoid 4 until the current detection signal Vi reaches the first value Vr1 of the reference voltage corresponding to the upper limit value of the holding current. Solenoid 4
When the current flowing through reaches the upper limit value Ih1 of the change range of the holding current and the current detection signal Vi becomes equal to or more than the first value Vr1 of the reference voltage, the output terminal of the comparator CP becomes the ground potential.
The transistors TR3 and TR2 are turned off.

By repeating these operations, the transistor TR1 turns on and off as shown in FIG.
The holding current flowing through the solenoid 4 changes between the upper limit value Ih1 and the lower limit value Ih2 as shown in FIG.

When the CPU stops generating the drive signal Vd, the transistor TR1 is turned off, and the supply of the drive current from the DC power supply 10 to the solenoid 4 is stopped. When the drive signal Vd disappears, the control section 14b of the switch control circuit 14 turns on the switch 14a, so that the transistor TR5 is turned off and the circuit for supplying the flyback current IF is cut off. Accordingly, when the drive signal Vd disappears, the current flowing through the solenoid 4 is instantaneously cut off, becomes smaller than the lower limit value Ih2 of the holding current, and the valve is immediately closed.

FIG. 3 shows another example of the configuration of the control apparatus for an internal combustion engine according to the present invention. FIG. 4 is a timing chart showing the operation of the apparatus shown in FIG. In the example shown in FIG.
Is omitted, and the cathode is directed to the rectifier 2 side between the connection point between the solenoid 4 and the main switch 7 and the positive (non-grounded) output terminal of the rectifier 2 instead. The diode Df is connected, and the diode Df forms a flyback current supply circuit. Other configurations are the same as those in the example shown in FIG.

In the case of the configuration shown in FIG.
U6 stops generating the drive signal Vd and the transistor TR
Since the flyback current IF flows through the solenoid 4 even after the switch 1 is turned off, the closing operation of the valve is delayed as shown in FIG.

FIG. 5 shows a main part of still another configuration example of the control device for an internal combustion engine according to the present invention.
The switch 15 for dividing the voltage dividing resistor provided in the apparatus of FIGS. 1 and 3 is omitted, and the emitter is grounded at both ends (between the output terminals of the current detection circuit) of the integration capacitor Ci of the current detection circuit 8 instead. The collector-emitter circuit of the NPN transistor TR6 is connected, and the base of the transistor TR6 is connected to the output terminal of the timer unit TM. Other points are the same as those of the control device shown in FIG. In this example, the transistor TR6 constitutes a switch 16 for short-circuiting the output terminals of the current detection circuit.

In the example shown in FIG. 5, the CPU 6 of the ECU 5
After the drive signal Vd is generated, the transistor TR6 keeps the ON state and short-circuits the integration capacitor Ci until the timer unit TM completes the timed operation. Therefore, the voltage input to the inverting input terminal of the comparator CP is kept substantially zero until the fixed time Tp elapses after the generation of the drive signal Vd. In this state, since the potential of the output terminal of the comparator CP is kept at a high level, a drive signal is supplied to the transistor TR1 constituting the main switch 7, and the transistor TR1 is turned on. When the timed operation of the timer unit TM is completed, the transistor TR6 is turned off, so that the voltage across the integrating capacitor Ci has a magnitude corresponding to the magnitude of the drive current of the solenoid 4. Thereafter, the same operation as that of the control device shown in FIG. 1 or 3 is performed. A timing chart showing the operation of the control device shown in FIG. 5 is as shown in FIG. In the timing chart of FIG. 5, it is assumed that the flyback current flow circuit is configured similarly to the example shown in FIG. Therefore, even after the drive signal Vd disappears, the flyback current flows through the solenoid, and the valve closing operation is performed with a certain delay time.

When the flyback current supply circuit is formed as shown in FIG. 1, a transistor TR6 forming a short-circuit switch is connected between both ends of the integrating capacitor Ci as shown in FIG. Of course you can.

In the example shown in FIG. 5, the integration capacitor Ci is short-circuited by the transistor TR6 until the fixed time Tp elapses after the generation of the drive signal Vd, but as shown in FIG. The transistor TR7 is connected so that both ends of the resistor r1 (between the input terminals of the current detection circuit 8) are short-circuited, and the drive current of the solenoid 4 is supplied for a predetermined time Tp after the drive signal Vd is generated. May be blocked. In the example of FIG. 6, the transistor TR7 constitutes the switch 17 for short-circuiting the input of the current detection circuit.

In the above example, a bipolar transistor is used as a switch element provided in the main switch 7 or the like. Instead of the bipolar transistor, another switch element capable of on / off control such as an FET may be used.

In the above example, when the CPU does not generate the drive signal Vd, the voltage dividing resistor short-circuit switch 15 (transistor TR4) and the current detection circuit output short-circuit switch 16
The (transistor TR6) or the current detection circuit input short-circuit switch 17 (transistor TR7) is kept on. However, these short-circuit switches are turned on at least during the timed operation of the timer unit. The switch 15 for short-circuiting the voltage dividing resistor, the switch 16 for short-circuiting the output of the current detection circuit, or the switch 17 for short-circuiting the input of the current detection circuit may be kept ON only during the period when the drive signal Vd is generated. Good.

[0072]

As described above, according to the present invention, the ECU
And the solenoid can be connected by a single line, so that there is an advantage that the wiring between the ECU and the solenoid can be simplified, and the device can be reduced in size and cost. .

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration example of a control device for an internal combustion engine according to the present invention.

FIG. 2 is a timing chart showing the operation of the control device of FIG.

FIG. 3 is a circuit diagram showing another configuration example of the control device for an internal combustion engine according to the present invention.

FIG. 4 is a timing chart showing an operation of the control device of FIG. 3;

FIG. 5 is a circuit diagram showing a main part of still another configuration example of the control device for an internal combustion engine according to the present invention.

FIG. 6 is a circuit diagram showing a main part of still another configuration example of the control device for an internal combustion engine according to the present invention.

FIG. 7 is a timing chart showing the operation of the control device of FIG.

FIG. 8 is a circuit diagram showing a configuration of a conventional control device for an internal combustion engine.

9 is a timing chart showing the operation of the control device of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... AC generator, 2 ... Rectifier with voltage adjustment function, 4 ... Solenoid of electromagnetic valve, 5 ... ECU (electronic control unit), 6 ... CPU, 7 ... Main switch, 8 ... Current detection circuit, 9 ... Drive current control Circuit, 10 ... DC power supply, 11 ...
Power supply circuit, 12: switch for conducting flyback current, 1
Reference numeral 3 represents a resistor voltage dividing circuit, 14 represents a switch control circuit, 15 represents a voltage dividing resistor short circuit switch, 16 represents a current detection circuit output short circuit switch, and 17 represents a current detection circuit input short circuit switch.
M: timer unit, CP: comparator, R5: feedback resistor.

Claims (6)

[Claims] 1. An ECU that controls a solenoid of an electromagnetic valve for an internal combustion engine, and a DC power supply having one output terminal grounded and the other output terminal connected to a power supply terminal on the non-ground side of the ECU. A CPU for generating a drive signal for instructing to drive the solenoid according to a predetermined control condition;
A main switch that is turned on when a drive signal is supplied from the CPU to flow a drive current from the DC power supply to the solenoid, and a current detection circuit that detects a drive current of the solenoid flowing through the main switch A drive current control circuit that controls the drive current so that the current detected by the current detection circuit is kept within a set range; and a flyback voltage induced in the solenoid when the main switch is turned off. A control device for an internal combustion engine, comprising: a flyback current supply circuit for supplying a flyback current to a solenoid; wherein a terminal connected to one end of a main switch of the ECU serves as a sole solenoid connection terminal of the ECU.
One end of the solenoid is connected to the other output terminal of the DC power supply, the other end is connected to the solenoid connection terminal, and the other end of the main switch is connected to a ground circuit through the current detection circuit. The control device for an internal combustion engine, wherein the flyback current supply circuit is provided between the solenoid connection terminal and the other output terminal of the DC power supply. 2. An ECU which controls a solenoid of an electromagnetic valve for an internal combustion engine, and a DC power supply having one output terminal grounded and the other output terminal connected to a power supply terminal on the non-grounded side of the ECU. A CPU for generating a drive signal for instructing to drive the solenoid according to a predetermined control condition;
A main switch that is turned on when a drive signal is supplied from the CPU to flow a drive current from the DC power supply to the solenoid, and a current detection circuit that detects a drive current of the solenoid flowing through the main switch A drive current control circuit that controls the drive current so that the current detected by the current detection circuit is kept within a set range; and a flyback voltage induced in the solenoid when the main switch is turned off. A control device for an internal combustion engine, comprising: a flyback current supply circuit for supplying a flyback current to a solenoid; wherein a terminal connected to one end of a main switch of the ECU serves as a sole solenoid connection terminal of the ECU.
One end of the solenoid is connected to the other output terminal of the DC power supply, and the other end is connected to the solenoid connection terminal. The flyback current energization circuit is connected to the solenoid connection terminal and the DC The current detection circuit is provided between the other output terminal of the power supply, the current detection circuit includes a current detection resistor connected between the other end of the main switch and a ground circuit, and a voltage across the current detection resistor. And a drive current control circuit, wherein the drive current control circuit maintains the current detected by the voltage across the integration capacitor of the current detection circuit within a set range. A control device for an internal combustion engine, comprising a circuit for intermittently driving a drive signal given from the CPU to the main switch at a predetermined duty ratio. . 3. An ECU that controls a solenoid of an electromagnetic valve for an internal combustion engine, and a DC power supply having one output terminal grounded and the other output terminal connected to a power supply terminal on the non-ground side of the ECU. A CPU for generating a drive signal for instructing to drive the solenoid according to a predetermined control condition;
A main switch that is turned on when a drive signal is supplied from the CPU to flow a drive current from the DC power supply to the solenoid, and a current detection circuit that detects a drive current of the solenoid flowing through the main switch A drive current control circuit that controls the drive current so that the current detected by the current detection circuit is kept within a set range; and a flyback voltage induced in the solenoid when the main switch is turned off. A control device for an internal combustion engine, comprising: a flyback current supply circuit for supplying a flyback current to a solenoid; wherein a terminal connected to one end of a main switch of the ECU serves as a sole solenoid connection terminal of the ECU.
One end of the solenoid is connected to the other output terminal of the DC power supply, and the other end is connected to the solenoid connection terminal. The flyback current energization circuit is connected to the solenoid connection terminal and the DC The current detection circuit is provided between the other output terminal of the power supply, the current detection circuit includes a current detection resistor connected between the other end of the main switch and a ground circuit, and a voltage across the current detection resistor. And a circuit for outputting a voltage across the integration capacitor as a current detection signal, the driving current control circuit being connected between output terminals of a constant voltage power supply circuit. A resistor voltage dividing circuit that is formed of a series circuit of an upper resistor and a lower resistor that generates a reference voltage at both ends of the lower resistor; Terminals, the current detection signal is input to the inverting input terminal, and the output terminal is connected to the drive signal input terminal of the main switch, and the voltage input to the inverting input terminal is input to the non-inverting input terminal. A comparator for preventing supply of a drive signal to the main switch when the voltage exceeds the set voltage, a feedback resistor connected between an output terminal and a non-inverting input terminal of the comparator, and A timer unit for starting a timed operation when a signal is generated, and at least a short circuit of a resistor on an upper side of the resistance voltage dividing circuit while the timer unit is performing the timed operation, so that a reference voltage is set higher than the maximum value of the current detection signal. A voltage dividing resistor short-circuit switch that raises the voltage to a high value, and when the drive current of the solenoid reaches the lower limit value of the set range, the voltage at both ends of the integrating capacitor is reduced. A control device for an internal combustion engine, wherein a time constant of charging and discharging of the integration capacitor is set such that a voltage is substantially equal to a value corresponding to a lower limit value of a setting range of the drive current. 4. An ECU that controls a solenoid of an electromagnetic valve for an internal combustion engine, and a DC power supply having one output terminal grounded and the other output terminal connected to a power supply terminal on the non-ground side of the ECU. A CPU for generating a drive signal for instructing to drive the solenoid according to a predetermined control condition;
A main switch that is turned on when a drive signal is supplied from the CPU to flow a drive current from the DC power supply to the solenoid, and a current detection circuit that detects a drive current of the solenoid flowing through the main switch A drive current control circuit that controls the drive current so that the current detected by the current detection circuit is kept within a set range; and a flyback voltage induced in the solenoid when the main switch is turned off. A control device for an internal combustion engine, comprising: a flyback current supply circuit for supplying a flyback current to a solenoid; wherein a terminal connected to one end of a main switch of the ECU serves as a sole solenoid connection terminal of the ECU.
One end of the solenoid is connected to the other output terminal of the DC power supply, and the other end is connected to the solenoid connection terminal. The flyback current energization circuit is connected to the solenoid connection terminal and the DC The current detection circuit is provided between the other output terminal of the power supply, the current detection circuit includes a current detection resistor connected between the other end of the main switch and a ground circuit, and a voltage across the current detection resistor. And a circuit for outputting a voltage across the integration capacitor as a current detection signal, the driving current control circuit being connected between output terminals of a constant voltage power supply circuit. A resistor voltage dividing circuit that is formed of a series circuit of an upper resistor and a lower resistor that generates a reference voltage at both ends of the lower resistor; Terminals, the current detection signal is input to the inverting input terminal, and the output terminal is connected to the drive signal input terminal of the main switch, and the voltage input to the inverting input terminal is input to the non-inverting input terminal. A comparator for preventing supply of a drive signal to the main switch when the voltage exceeds the set voltage, a feedback resistor connected between an output terminal and a non-inverting input terminal of the comparator, and A timer unit that starts timed operation when a signal is generated, and a current detection circuit output short-circuit switch that short-circuits between output terminals of the current detection circuit at least while the timer unit is performing timed operation; When the drive current of the drive current reaches the lower limit of the set range, the voltage across the integrating capacitor becomes substantially equal to the value corresponding to the lower limit of the set range of the drive current. A control device for an internal combustion engine, wherein a time constant of charging and discharging of the integration capacitor is set to be equal. 5. An ECU that controls a solenoid of an electromagnetic valve for an internal combustion engine, and a DC power supply having one output terminal grounded and the other output terminal connected to a power supply terminal on the non-ground side of the ECU. A CPU for generating a drive signal for instructing to drive the solenoid according to a predetermined control condition;
A main switch that is turned on when a drive signal is supplied from the CPU to flow a drive current from the DC power supply to the solenoid, and a current detection circuit that detects a drive current of the solenoid flowing through the main switch A drive current control circuit that controls the drive current so that the current detected by the current detection circuit is kept within a set range; and a flyback voltage induced in the solenoid when the main switch is turned off. A control device for an internal combustion engine, comprising: a flyback current supply circuit for supplying a flyback current to a solenoid; wherein a terminal connected to one end of a main switch of the ECU serves as a sole solenoid connection terminal of the ECU.
One end of the solenoid is connected to the other output terminal of the DC power supply, and the other end is connected to the solenoid connection terminal. The flyback current energization circuit is connected to the solenoid connection terminal and the DC The current detection circuit is provided between the other output terminal of the power supply, the current detection circuit includes a current detection resistor connected between the other end of the main switch and a ground circuit, and a voltage across the current detection resistor. And a circuit for outputting a voltage across the integration capacitor as a current detection signal, the driving current control circuit being connected between output terminals of a constant voltage power supply circuit. A resistor voltage dividing circuit that is formed of a series circuit of an upper resistor and a lower resistor that generates a reference voltage at both ends of the lower resistor; Terminals, the current detection signal is input to the inverting input terminal, and the output terminal is connected to the drive signal input terminal of the main switch, and the voltage input to the inverting input terminal is input to the non-inverting input terminal. A comparator for preventing supply of a drive signal to the main switch when the voltage exceeds the set voltage, a feedback resistor connected between an output terminal and a non-inverting input terminal of the comparator, and A timer unit for starting a timed operation when a signal is generated, and a current detection circuit input short circuit switch for shorting between input terminals of the current detection circuit at least while the timer unit is performing the timed operation; When the drive current of the drive current reaches the lower limit of the set range, the voltage across the integrating capacitor becomes substantially equal to the value corresponding to the lower limit of the set range of the drive current. A control device for an internal combustion engine, wherein a time constant of charging and discharging of the integration capacitor is set to be equal. 6. The flyback current supply circuit is connected between one end of the main switch and the other output terminal of the DC power supply, and is turned on when the flyback voltage is induced, so that the flyback current supply circuit is turned on. A flyback current energizing switch for flowing a current, wherein the flyback current energizing switch is allowed to be turned on when the CPU generates a drive signal, and the CPU stops generating the drive signal when the CPU stops generating the drive signal. The internal combustion engine according to any one of claims 1 to 5, further comprising a switch control circuit that controls the flyback current supply switch so as to forcibly turn off the flyback current supply switch. Control device.