JPH0441235Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a control device for an internal combustion engine, and more specifically, to a control device for reliably starting an internal combustion engine whose operation is controlled by an electronic circuit, a microcomputer, etc. Regarding equipment.

In recent years, various internal combustion engine devices whose operation is controlled by electronic devices such as microcomputers have been proposed, but these types of devices are more susceptible to fluctuations in battery voltage than conventional devices. However, there are problems such as the inability to perform normal control operations due to a drop in battery voltage.

For example, in the case of an electronic internal combustion engine device in which the adjustment operations of each part of the internal combustion engine device are controlled by a microcomputer, if a large current flows through the battery due to the operation of the starting motor or glow plug, the terminals of the battery may There is a risk that the voltage will drop and the program will run out of control within the microcomputer. Particularly in the winter, the performance of the battery is degraded, and a larger starting current flows due to the increased viscosity of the oil in the engine, so the drop in battery terminal voltage becomes even more significant. Furthermore, in the case of a diesel engine, the resistance value of the glow plug is further reduced due to the low temperature, and this also causes a tendency for the terminal voltage of the battery to decrease significantly. The battery terminal voltage decreases due to the various reasons mentioned above. In some cases, for example, when the specified voltage is 12V, the battery terminal voltage may drop to about 3V. If this causes a program to run out of control, the required voltage may drop. Not only will the engine become uncontrollable, but there is a risk that the engine will fall into a dangerous operating state. Therefore, a control device has been adopted that is configured to reset the control circuit, cut off the fuel supply, and stop the engine when the terminal voltage of the battery drops below a predetermined value (Japanese Patent Laid-Open No. 57-62405).
Publication No.).

However, in the conventional control device configured as described above, the battery voltage often decreases during startup, especially when the battery performance is degraded.
Each time, the fuel cut valve operates and the actuator that drives the fuel adjustment member is turned off.
Since the supply of fuel is stopped, the engine becomes difficult to start due to an unexpected increase in starting fuel, and there are problems such as the engine becoming impossible to start.

In addition, JP-A-58-44233 discloses that when the starting voltage drops, the adjustment device that drives the member that controls the fuel supply amount is separated from the signal processing circuit and connected directly to the power supply voltage supply line. A fuel supply amount control device that obtains a starting amount is disclosed. However, the decrease in battery voltage at the time of start is affected by the rotation of the internal combustion engine, and its level varies as the engine rotates. For this reason, smooth control of the fuel supply amount at the time of start cannot be expected with the control based on the output of the comparison switch shown in the above-mentioned conventional device.

Therefore, an object of the present invention is to provide a control device for an internal combustion engine that can eliminate difficulty in starting the engine due to a drop in battery voltage when starting the engine, and can significantly improve starting performance. There is a particular thing.

Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments.

FIG. 1 shows an embodiment of an internal combustion engine-like control device according to the present invention. This internal combustion engine control device 1 is a device for controlling the starting operation of a diesel engine equipped with an electronically controlled fuel injection pump, and includes a control unit 2 for controlling a fuel injection pump (not shown). and the control unit 2
The fuel cut solenoid valve 3 and the governor actuator 4 are provided between the fuel cut solenoid valve 3 and the governor actuator 4.

The control unit 2 includes a microcomputer (not shown), and determines the optimal fuel injection amount at any given time in response to input data D ₁ , D ₂ , ...D _o indicating the operating state of a diesel engine (not shown). The calculation results are output as target injection amount data Da and input to the servo circuit 5.
The servo circuit 5 also includes a position signal S ₁ indicating the actual position of the fuel adjustment member (not shown) of the injection pump.
is input, and a position control signal _S2 is used to position the fuel adjustment member at a position where the injection amount indicated by the target injection amount data Da is obtained.
is output in response to both input signals. The position control signal _S2 is a pulse signal whose duty ratio is determined according to the position to be controlled, and is a pulse signal whose duty ratio is determined according to the position to be controlled.
The output is applied to a driver 8 connected to the governor actuator 4 via the OR gate 7 and the OR gate 7 .

The governor actuator 4 is an electromagnetic actuator connected to a fuel adjustment member (for example, a control sleeve), and is driven on/off according to level changes of the position control signal _S2 , and adjusts the fuel to a position according to its duty ratio. A member is positioned. The control result is fed back to the servo circuit 5 as a position signal _S1 , so that the optimal fuel injection amount calculated by the control unit 2 is always supplied to the diesel engine.

The control unit 2 also determines whether or not to close the fuel cut solenoid valve 3 using input data D ₁ , D ₂ ,
. . . It is configured to output a control signal S ₃ for controlling the opening and closing of the fuel cut electromagnetic valve 3 from the state of _Do. The control signal _S3 is applied to the driver 11 whose output is connected to the fuel cut electromagnetic valve 3 via the AND gate 9 and the OR gate 10, and the level of the control signal _S3 becomes "L" level. In response to this, Driver 1
When the output level of the pump 1 reaches the "H" level, the fuel cut electromagnetic valve 3 is deenergized and the supply of fuel to the fuel injection pump is cut off.

The internal combustion engine control device 1 eliminates the difficulty of starting due to a drop in battery voltage at the time of starting and provides good starting characteristics in the electronically controlled fuel injection system configured as described above. It is provided for this purpose and includes a voltage drop detection circuit 12. The voltage drop detection circuit 12 includes a battery 1.
An output voltage Vcc from a constant voltage circuit 14 that stabilizes the terminal voltage E of No. 3 and outputs a DC output voltage at a predetermined constant level is applied, and the DC output voltage Vcc
When the level of the output voltage V1 falls below a predetermined level Va, the level of the output voltage _V1 becomes the "V" level, and when the level of the DC output voltage Vcc is equal to or higher than Va, the level of the output voltage _V1 becomes the "H" level. becomes.

The output voltage V ₁ from the voltage drop detection circuit 12 is
The input is input to a retrigger type monostable multivibrator 15, and in response to the level of the output voltage _V1 changing from "H" level to "L" level, monostable multivibrator 15 is triggered, and its output The level of voltage _V2 changes from "L" level to "H"
level, and the "H" level state is maintained for a certain period of time. The output voltage V ₁ is also connected to a reset circuit 16 for resetting the control unit 2.
The reset circuit 16 outputs a reset signal _S4 in response to the output voltage _V1 being at the "L" level, thereby placing the control unit 2 in a reset state. Furthermore, a circuit for detecting a program runaway in the microcomputer is built into the control unit 2, and a detection pulse signal _S5 output in response to the detection of a program runaway is incorporated into the control unit 2. The reset circuit 16 is also activated so that the control unit 2 can be reset.

The output voltage V ₂ is applied to the first input of the three-input AND gate 17, and the start signal S ₆ and the overrun detection signal S ₇ are applied to the second and third inputs thereof.
are applied respectively. The start signal _S6 is a signal that becomes "H" level when a key switch (not shown) is positioned at the start position (see FIG. 2f). On the other hand, overrun detection signal S ₇
is a signal output from a rotation speed detection circuit (not shown) in response to the rotation speed of the diesel engine becoming equal to or higher than a predetermined upper limit, and when the engine speed is lower than the predetermined upper limit, ” level, but when the engine speed exceeds a predetermined upper limit value, it becomes the “L” level. The output terminal of the AND gate 17 is connected to the input terminal of each OR gate 7,10. An overrun detection signal _{S7 and} a failure detection signal _S8 indicating that a failure has occurred in the microcomputer in the control unit 2 are applied to the other input terminal of the AND gate 9 to which the control signal S3 is input. ing. The fault detection signal _S8 is output from the control unit 2, and is at the "H" level when the microcomputer is operating normally, but becomes the "L" level when some fault occurs in the microcomputer. The output terminal of the AND gate 9 is connected to the input terminals of the OR gate 10 and the AND gate 6. Therefore, the level of the output of the AND gate 6 changes as shown in FIG. 2g.

Next, the operation of the internal combustion engine control device shown in FIG. 1 will be explained with reference to the signal waveform diagrams shown in FIGS. 2a to 2h.

When the key switch (not shown) is turned on,
The switch 18 is closed and the output voltage Vcc output from the constant voltage circuit 14 is supplied to each part. In this case, since the terminal voltage E is a specified value, the value of the output voltage Vcc is a specified value (FIGS. 2a and 2h). When the key switch is switched to the start position at time t= _t1 , the start signal _S5
Since the starting motor becomes "H" (Fig. 2 f) and the starting motor is connected as a load to the battery 13, a large current flows through the battery 13, the level of the terminal voltage E decreases greatly, and the constant voltage circuit 14 The voltage level V L is lower than the voltage level V _L required to maintain the level of the output voltage Vcc at a predetermined specified value. Terminal voltage E
This level drop occurs not only immediately after starting, but also every time the engine enters the compression process. Therefore, the level change of the terminal voltage E occurs periodically in synchronization with the starting motor, as shown in Figure 2a. It will fluctuate.

The level of the output voltage Vcc is maintained at a predetermined specified value when the terminal voltage E is greater than V _L ;
When the terminal voltage E becomes lower than V _L , the constant voltage circuit 14 no longer performs constant voltage operation, and the output voltage Vcc
The level of is reduced as shown in FIG. 2b. The voltage drop detection circuit 12 detects the above-mentioned drop in the output voltage Vcc, and outputs an output voltage _V1 that becomes "L" level when the output voltage Vcc becomes smaller than the voltage Va.

The reset circuit 16 operates in response to the output voltage _V1 changing from the "H" level to the "L" level, and outputs a reset signal _S4 . The reset signal _S4 changes the output voltage _V1 from "H" level to "L" level.
After the output voltage V ₁ returns from the "L" level to the "H" level, it returns to the "H" level with a slight time delay (Fig. 2 d). ). The control unit 2 is
It is reset when the reset signal _S4 goes to the "L" level, and the reset state is released when the reset signal S4 goes to the "H" level again.

The output voltage V ₁ is also input as a trigger signal to the monostable multivibrator 15, and the monostable multivibrator 15 is triggered at falling points t ₁ , t ₂ , t ₃ , ... of the output voltage V _{1 .} , the level of its output voltage _V2 is changed from "L" level to "H" level.
Change the level. The pulse width T ₀ of the pulse output when the monostable multivibrator 15 is triggered is determined by the time T ₁ , T ₂ , ... required for the engine to move from one compression stroke to the next compression stroke during cranking. It is set to be large. Therefore, under cranking conditions in which the terminal voltage of the battery decreases with each compression stroke and the level of the output voltage _V1 goes to the "L" level each time, the monostable multivibrator 15 lowers its output voltage V1. Since the level of the output voltage _V2 continues to be triggered before returning to the "L" level, the level of the output voltage _V2 continues to be held at the "H" level state. That is, during the period when the level state of the voltage Vcc is unstable, the level of the output voltage _V2 of the monostable multivibrator 15 continues to be held at the "H" level. After time _t4 , when the engine completes explosion and the output voltage Vcc level becomes stable, monostable multivibrator 1
5 is no longer triggered after t ₄ , the level of output voltage V ₂ becomes “L” level after time T ₀ has elapsed from time t ₄ .

Thus, the output voltage V ₂ is the regulated output voltage
This is a signal indicating whether Vcc is normal or abnormal.

Therefore, the output level of the AND gate 17 is
Provided that the engine is not in an overrun state, when the start signal S ₆ is at the "H" level and the output voltage V ₂ is at the "H" level,
The output level becomes "H" level, and the output level of each driver 8, 11 is set to "L" level regardless of the level of each output of AND gates 6, 9. As a result, the key switch is in the starting position and the regulated output voltage is
When the Vcc level is unstable, the output of the AND gate 17 forces the fuel cut solenoid valve 3 into an open state, while the governor actuator 4
continues to be energized by the battery 13. By the way, during cranking, the battery voltage decreases as described above, so even if the output level of the inverter 8 is maintained at the "L" level, the fuel adjustment member cannot be continuously maintained fully in the fuel increasing direction. The position P of the fuel adjustment member is shown in Fig. 2h.
As shown in FIG. 2, the displacement occurs between the maximum fuel supply amount position Pmax and the minimum fuel supply amount position Pmin in accordance with the change in the terminal voltage E of the battery.

Due to the complete explosion of the engine, the terminal voltage E of the battery rises, and the level of the output voltage _V2 becomes "H" at t= _t5 .
When the level changes from the level to the "L" level, the output level of the AND gate 17 becomes the "L" level, and from then on, the fuel cut solenoid valve 3 and the governor actuator 4 are controlled by the outputs from the AND gates 9 and 6, respectively. That will happen. That is, the fuel cut electromagnetic valve 3 is turned off due to an overrun, a failure of the control unit 2, or a fuel cut command from the control unit 2, and the fuel supply is stopped.
On the other hand, the governor actuator 4 is connected to the AND gate 9
As long as the output of the servo circuit 5 is at "H" level, the servo circuit 5
Depending on the level change of the position control signal _S2 from
It is controlled ON and OFF (see Fig. 2g), and the fuel adjustment member is positioned in accordance with the duty ratio of the position control signal _S2 .

If the terminal voltage E of the battery does not fall below the level V _L between times t ₁ and t ₄ , the monostable multivibrator 15 will not be triggered, and therefore the governor actuator 4 will not be triggered. Driving is performed according to the duty ratio of the position control signal _S2 output from the servo circuit 5.

According to the above-mentioned configuration, when the decrease in the terminal voltage E of the battery during cranking becomes less than the predetermined value V _L , this is detected and the drive current is made to flow continuously to the governor actuator 4. Therefore, even if the control unit 2 is reset in response to a drop in the battery terminal voltage, the
The engine can be forced to start.

Although the above embodiment has been explained using a diesel engine as an example, the present invention is not limited to this embodiment and can be similarly applied to a gasoline engine. be.

According to the present invention, as described above, even if the control unit of the internal combustion engine is reset due to an abnormal drop in the terminal portion of the battery, the level drop timing at which the level of the DC current generated at the time of starting falls below a predetermined level is detected, By triggering the signal generating means at each timing of this level drop and outputting a pulse signal with a predetermined duration longer than the pulsation period of the DC output voltage level that occurs during cranking, the Continuous supply of the power supply output voltage to the actuator is performed as necessary during the level drop period of the DC power supply. Therefore, even if the output voltage level of the DC power supply periodically decreases as the engine rotates, the power supply output voltage will continue to be supplied to the actuator until the power supply voltage level stably returns to a predetermined level or higher. The operation to ensure the necessary amount of fuel supply is performed stably. Further, while the engine is in a state where the level of the DC power source is lower than at least a predetermined level, the control unit is reset by the reset means which operates in response to the detection means. As a result, the internal combustion engine can be started reliably and stably regardless of a drop in battery voltage.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the apparatus according to the present invention, and FIGS. 2a to 2h are time charts for explaining the operation of the apparatus shown in FIG. 1. DESCRIPTION OF SYMBOLS 1... Control device for internal combustion engine, 2... Control unit, 3... Solenoid valve for fuel cut, 4... Governor actuator, 5... Servo rotation, 6, 9, 17...
...and gate, 7,10...or gate, 8,
11... Driver, 12... Voltage drop detection circuit, 13... Battery, 14... Constant voltage circuit, 1
7... Monostable multivibrator, D ₁ , D ₂ ...
D _o ...Input data, _S2 ...Position control signal, _S3 ...
...Control signal, Vcc...Output voltage, _V1 , _V2 ...Output voltage, _S4 ...Reset signal, _S5 ...Detection pulse signal, _S6 ...Start signal.

Claims (1)

[Scope of utility model registration request] An electronically controlled system comprising: an actuator connected to a fuel supply regulating means of an internal combustion engine; and a control unit that electrically controls the actuator to provide optimal fuel supply according to the operating state of the internal combustion engine. In a control device for an internal combustion engine device, a detection means detects a voltage drop timing at which an output voltage level of a DC power source that supplies power to the electronically controlled internal combustion engine device becomes smaller than a predetermined value at which the control unit becomes inoperable. , a predetermined time width that is triggered at each of the voltage drop timings detected by the detection means in response to the detection means, and is longer than the pulsation period of the level of the DC output voltage that occurs during cranking every time it is triggered. a signal generating means for re-outputting a pulse signal of the internal combustion engine; and a start signal provided between the actuator and the control unit and output in response to an output signal from the signal generating means and a starting operation of the internal combustion engine apparatus. means for continuously supplying the output voltage to the actuator to increase the amount of fuel supplied when the start signal is output during the output period of the output signal in response to the detection signal from the detection means; A control device for an internal combustion engine, comprising a reset means for maintaining the control unit in a reset state at least during the output period of the detection signal.