JPH0569977B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel supply control method for a multi-cylinder internal combustion engine, and more particularly to a fuel supply control method during startup.

A fuel supply control method in which an electronic fuel injection control device electrically calculates the amount of fuel to be supplied to an internal combustion engine based on a parameter signal representing the operating state of the engine includes a central processing unit built in the electronic fuel injection control device. The injection order is determined by a cylinder discrimination signal generated once per cycle of the engine at a predetermined position on the crankshaft of the engine, and a timing signal indicating the predetermined position of the crankshaft corresponding to the injection timing of each cylinder is generated. There is a fuel supply control method that sequentially injects and supplies fuel to each cylinder. There is also a fuel supply control method that simultaneously injects fuel into all cylinders using the first timing signal during startup.

By the way, when starting the engine, especially when starting cold, when the starter is driven, the battery voltage decreases.
As a result, the voltage may drop below the operating voltage of the central processing unit that controls the amount of fuel to each cylinder, and at this time, the terminal voltage of the starter, that is, the battery voltage fluctuates pulsatingly, and as a result, the central processing unit The device injects fuel into all cylinders at every injection timing signal after the battery voltage has returned to the operating voltage of the central processing unit, and the next fuel is injected while the previously injected fuel has not yet been inhaled. It will be injected. Therefore, if such an operation is repeated two or three times, there is a risk of excess fuel, that is, overload, and there are problems such as a decrease in engine startability.

In addition, if the battery voltage drops due to some abnormality during engine operation and the supply voltage to the central processing unit falls below the operating voltage, normal fuel injection will not be performed and the engine will jerk and become unstable. There is a problem with the engine not being able to run.

The present invention has been made in view of the above-mentioned points, and prevents an excessive amount of fuel injection at the time of starting (hereinafter referred to as "overbalance"), obtains good starting performance against battery voltage drop, and also provides a system that prevents excessive fuel injection during starting. The purpose of this invention is to enable stable engine operation to continue even when the battery voltage drops.

In order to achieve this purpose, in the present invention,
A cylinder discrimination signal generated once per cycle of the engine at a predetermined position of the crankshaft of the engine and a timing signal indicating the predetermined position of the crankshaft are input to the central processing unit of the electronic control unit, and the central processing unit When the operating voltage is higher than a predetermined voltage, all fuel injection valves are simultaneously opened every time the timing signal is input until the cylinder discrimination signal is input for the first time after starting. In the fuel supply control method for a multi-cylinder internal combustion engine, in which the fuel injection valves corresponding to the respective timing signals are sequentially opened after a cylinder discrimination signal is input, when the operating voltage does not reach the predetermined voltage. , a multi-cylinder internal combustion engine in which all fuel injection valves are simultaneously opened for each timing signal in accordance with the timing signal by operating a low voltage operation circuit independent from the central processing unit instead of the central processing unit. The fuel supply control method and the low voltage operating circuit provide a fuel supply control method for a multi-cylinder engine that sets the opening time of a fuel injection valve in accordance with at least one engine operating parameter.

An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows an overall configuration diagram of a fuel supply control device to which the present invention is applied, in which an engine 1 is a multi-cylinder engine, for example a four-cylinder engine, equipped with an auxiliary combustion chamber, and an intake pipe 2
consists of a main intake pipe 2a communicating with each main combustion chamber and a sub-intake pipe 2b communicating with each sub-combustion chamber, and a throttle body 3 is provided in the middle of the intake pipe 2.
Inside, there are a main throttle valve 3a and a sub-throttle valve 3 disposed in the main intake pipe 2a and the sub-intake pipe 2b, respectively.
b are provided in conjunction with each other. Main throttle valve 3
A throttle valve opening sensor 4 is connected to the main throttle valve 3a, which converts the valve opening of the main throttle valve 3a into an electrical signal and sends it to an electronic control unit (hereinafter referred to as ECU).
Supply to 5.

A main fuel injection valve 6 and an auxiliary fuel injection valve 7 are provided in the main intake pipe 2a and the auxiliary intake pipe 2b, respectively, and the main fuel injection valve 6 is located slightly upstream of an intake valve (not shown) in the main intake pipe 2a for each cylinder. Only one auxiliary fuel injection valve 7 is provided in the auxiliary intake pipe 2b, slightly downstream of the auxiliary throttle valve 3b, in common to each cylinder. The main fuel injection valve 6 and the auxiliary fuel injection valve 7 are each connected to a fuel pump (not shown) and are electrically connected to the ECU 5, and the opening time of fuel injection is controlled by a control signal from the ECU 5. . An absolute pressure sensor 9 is provided immediately downstream of the throttle valve 3a via a pipe 8, and is connected to the ECU 5.

Engine water temperature sensor 10 is installed in the main body of engine 1.
The sensor 10 is made of a thermistor, etc., and is installed in the circumferential wall of the engine cylinder filled with cooling water, and supplies a detected water temperature signal to the ECU 5. Also, engine speed sensor (hereinafter referred to as TDC sensor)
11 and a cylinder discrimination sensor (hereinafter referred to as CYL sensor) 12 are respectively installed around a camshaft (not shown) or a distributor shaft of the engine 1, and the TDC sensor 11 is installed at a predetermined position on the crankshaft corresponding to the injection timing of each cylinder. The CYL sensor 12 generates a cylinder discrimination signal once per cycle of the engine at a predetermined position of the crankshaft. These timing signals and cylinder discrimination signals are supplied to the ECU 5.

The ECU 5 is connected to a battery 17 via an ignition switch 16a of the key switch 16, and is supplied with operating voltage from the battery 17 when the switch is turned on. Starter 18 is key switch 16
battery 17 via starter switch 16b
connected to. Further, the connection point between the starter 18 and the key switch 16b is connected to the ECU, so that the ECU 5 detects the terminal voltage of the starter 18 at the time of starting, that is, the battery voltage at the time of starting.

FIG. 2 is a flowchart showing the procedure of the control method of the present invention, which will be explained with reference to the timing chart of FIG. 4. At the time of startup, it is determined whether the power supply voltage supplied to the ECU 5 is higher than the operating voltage of the central processing unit in the ECU (step
20), if the answer is negative (No), backup simultaneous injection (Fig. 4 d, e) is performed based on other electronic circuits without control by the central processing unit (step 22). If the answer is affirmative (Yes), it is determined whether the cylinder discrimination signal CYL has been input even once after starting (step 23), and if the answer is negative (No), the control is applied to all cylinders simultaneously every time the TDC signal is input. Injection (Fig. 4 a, b, d, e) is performed (step 24), and the value i is set to a predetermined value 4 (step 25). This value 4 may be a value corresponding to the number of cylinders, or may be set to any integer larger than the number of cylinders.

If the answer to step 23 is affirmative (Yes), it is determined whether the CYL signal has been input more than once after startup (step 26), and if the answer is negative (No), simultaneous injection is performed and the number of cylinders is reduced. (Step 27),
If the answer is yes, the injections are made sequentially (step 28).

The control to reduce the number of cylinders for simultaneous injection in step 27 is performed according to the flowchart shown in FIG. That is, it is determined whether the predetermined value i is 4 or not (step 30), and if the answer is affirmative (Yes), the cylinder determination signal CYL ₁ is first output after starting (Fig. 4a).
The timing signal that is input immediately after is input.
Simultaneous injection (Fig. 4 b, e) is performed in all cylinders indicated by cylinder numbers #1, 3, 4, and 2 by TDC (step 31), and the value 1 is subtracted from the predetermined value i (=4) (step 31). 32). If the answer to step 30 is negative (No), it is determined whether the value i is 3 or not (step 33), and if the answer is affirmative (Yes), it is determined that this is the second simultaneous injection and the injection is started. Simultaneous injection to other cylinders #3, 4, and 2 except cylinder #1 (Figure 4 e)
and proceed to step 32.

If the answer in step 33 is negative (No), it is determined whether the predetermined value i is 2 (step 33).
35), if the answer is affirmative (Yes), it is determined that it is the third simultaneous injection, and the simultaneous injection is performed in the other cylinders #4 and 2, excluding the first and second cylinders #1 and 3. Perform step e) in Figure 4 (step 36) and proceed to step 32. If the answer to step 35 is negative (No), the remaining cylinders #2 (4th
Inject fuel as shown in Figure e) and proceed to step 32.

The first input after startup as described above
Simultaneous injection is performed in all cylinders by the TDC signal immediately after the CYL ₁ signal, and simultaneous injection is performed every time the TDC signal is input until the second CYL ₂ (Fig. 4 a) signal is input. Gradually reduce the number of cylinders. When the second CYL signal is input after starting, injections are sequentially performed in a predetermined order (Fig. 4e) every time the timing signal TDC is input thereafter. Note that the sub-injection valve is driven every time the timing signal TDC is input, regardless of the cylinder discrimination signal CYL.

FIG. 5 shows the circuit configuration within the ECU shown in FIG.

When the ignition switch 16a that constitutes the key switch 16 is turned on, the battery 17
The power supply voltage is supplied to a constant voltage circuit 501, and the constant voltage circuit 501 outputs a constant voltage Vcc. This constant voltage Vcc is supplied to the main calculation control circuit 503 and the voltage drop detection circuit 502. TDC sensor 12
The trigger signal (FIG. 6a) output from the long shot circuit 504 is supplied to the one shot circuit 504, and the output pulse signal (FIG. 6 b) of the long shot circuit 504 is supplied to the delay circuit 505a of the low voltage operation circuit 505, the one shot circuit 505b, 505c, integral circuit 505
d, 505e and the main operation control circuit 503. The output signal of the water temperature sensor 10 is transmitted to the comparator 5 of the main calculation control circuit 503 and the low voltage operating circuit 505.
It is supplied to the non-inverting input terminal of 05h.

The main calculation control circuit 503 performs a one-shot circuit 504 based on engine parameter signals output from various sensors such as the water temperature sensor 10 shown in FIG.
Each time a pulse signal synchronized with _{the TDC} signal _input from Calculate _S and output the corresponding valve opening control signal.

T _{OUT M} = Ti _M ×K ₁ + TK ₂ ... (1) T _{OUT S} = Ti _S × K' ₁ + TK' ₂ ... (2) Furthermore, the main operation control circuit 503 performs simultaneous injection at the time of starting. The valve opening time T _{OUT M} ' is calculated and the corresponding valve opening control signal is output. The valve-opening time during this simultaneous injection is set to a predetermined times the valve-opening time during normal times, for example, one times the number of cylinders, ie, one-fourth times in the case of four cylinders.

T _{OUT M} ′=(Ti _M ×K ₁ )/4+TK ₂ ...(3) Here, Ti _M and Ti _S indicate the basic injection times of the main fuel injection valve 6 and the auxiliary fuel injection valve 7, respectively, and these Each basic fuel injection time is calculated according to, for example, the intake pipe absolute pressure P _BA and the engine rotation speed Ne.
The coefficients K ₁ , K' ₁ and the correction values TK ₂ , TK' ₂ are correction coefficients and correction values that are calculated according to the engine parameter signals from each sensor mentioned above, and in particular, the correction values
TK ₂ and TK′ ₂ are voltage correction values, which are calculated based on a predetermined calculation formula to optimize various characteristics such as starting characteristics, exhaust gas characteristics, fuel consumption characteristics, and engine acceleration characteristics depending on the engine operating condition. is calculated.

The valve opening control signal for the main fuel injection valve 6 is output separately for the main fuel injection valves 6a to 6d of each cylinder, and as described later, AND circuits 521 to 524 and OR circuit 526 are sequentially opened each time a TDC signal is generated. ~
The signal is sequentially supplied to each drive circuit 531 to 534 via 529. Each of the drive circuits 531 to 534 outputs a drive signal while the valve opening signal is input to open the corresponding main fuel injection valve 6a to 6d.

On the other hand, the valve opening control signal of the auxiliary fuel injection valve 7 is TDC
An AND circuit 520 and an OR circuit 5 are output each time a signal is input and are in an open state as described later.
25 to the drive circuit 530. This drive circuit 530 outputs a drive signal to control the opening of the auxiliary fuel injection valve 7 while the valve opening signal is being input.

The voltage drop detection circuit 502 determines whether the output voltage Vcc of the constant voltage circuit 501 is equal to or higher than a predetermined voltage (operating voltage) at which the central processing circuit (hereinafter referred to as CPU) (not shown) in the main arithmetic control circuit 503 can operate normally. When the voltage is above a predetermined voltage, a low level signal is output, and when the voltage is below a predetermined voltage, a high level signal is output. This voltage drop detection circuit 5
The output signal of 02 is supplied to one input terminal of AND circuits 520 to 524 via main operation control circuit 503, one input terminal of AND circuits 511 to 515, and inverter 508.

Thus, the AND circuits 520 to 524 are open when the output of the voltage drop detection circuit 502 is low level, that is, when the output voltage Vcc of the constant voltage circuit 501 is higher than the operating voltage of the CPU, and when it is high level, that is, when the output voltage Vcc of the constant voltage circuit 501 is higher than the operating voltage of the CPU, When the voltage Vcc is lower than the operating voltage of the CPU, it is in a closed state. On the contrary, AND circuit 511
~515 is the output voltage of the constant voltage circuit 501 when the output of the voltage drop detection circuit 502 is at a high level.
It is in a closed state when Vcc is below the operating voltage of the CPU, and is in an open state when it is at a low level.

The low voltage control circuit 505 is configured to operate at a voltage lower than the operating voltage of the CPU, and the delay circuit 505a is configured to operate at a voltage lower than the operating voltage of the CPU.
The timing signal inputted from 4, that is, the TDC signal, is delayed by a predetermined time and is output to the one-shot circuit 505.
b and 505c. One shot circuit 5
05b is for setting the opening time of the auxiliary fuel injection valve after starting when the low voltage control circuit 505 is activated, and when a pulse signal is input from the delay circuit 505a, as shown in c in FIG. A pulse signal having a time width corresponding to the opening time of the auxiliary fuel injection valve after startup is output and supplied to one input terminal of the AND circuit 505k.

The one-shot circuit 505c is for setting the opening time of the main and auxiliary fuel injection valves for starting when the low voltage control circuit 505 is activated, and the opening time of the main fuel injection valve after starting. As shown, the integrating circuit 505d outputs a pulse signal of a predetermined time width,
505e. One shot circuit 505
b, 505c are reset by the output pulse of the one-shot circuit 504 in order to restart with the TDC signal when the output time becomes longer than the interval of the TDC signal.

The integral circuit 505d is for setting the opening time of the main and auxiliary fuel injection valves for starting, and the opening time is determined by the main calculation control circuit 503 as the opening time of the main fuel injection valve during sequential injection control. The integral time constant is set to be small, for example, 1/4 of the number of cylinders (Fig. 6e). The integral circuit 505e is for setting the main fuel injection time after startup, and its integral constant is set to be sufficiently large compared to the time constant of the integral circuit 505d, for example, twice the number of cylinders (FIG. 6 f). ).

The output voltages of the integrating circuits 505d and 505e are applied to the comparator 50 via field effect transistors (hereinafter simply referred to as transistors) 505f and 505g, respectively.
It is supplied to the inverting input terminal of 5h. This comparator 5
As described above, the output voltage of the engine coolant temperature sensor 10 is supplied to the non-inverting input terminal 05h. The conduction (on) or non-conduction (off) of each of these transistors 505f and 505g is determined depending on whether the engine is being started or after it has been started.

That is, when the starter switch 16b is turned on by operating the key switch 16 and the starter 18 is activated to start the engine 1, the output of the level correction circuit 506 becomes high level, and the inverter 5
07 to turn off the transistor 505g, which is inverted to a low level, and the inverter 5
It is inverted at 05i and becomes high level, turning on the transistor 505f. Therefore, during engine starting, the output voltage of the integrating circuit 505d is supplied to the comparator 505h via the transistor 505f.
When the key switch 16b is opened (off) after starting the engine, the output of the level correction circuit 506 becomes low level, and contrary to the above, the transistor 5
05f is turned off and transistor 505g is turned on. Therefore, after starting, the output voltage of the integrating circuit 505e is applied to the comparator 505 via the transistor 505g.
h.

The output of the comparator 505h remains at a high level while the output voltage of the temperature sensor 10 is higher than the output voltage of the integrating circuit 505d or 505e. The lower the engine water temperature, the higher the output voltage of the water temperature sensor 10, and correspondingly, the higher level output time of the comparator 505h becomes longer. The output signal of the comparator 505h is supplied to the AND circuits 512 to 515 through the AND circuit 505m, which is closed while the output of the one shot circuit 505c is at a high level, and the AND circuits 512 to 515 are kept in the open state. At the same time, an AND circuit 505n and an OR circuit 505 are opened while the transistor 505f is on.
It is supplied to the AND circuit 511 via p.

Further, the output of the one-shot circuit 505b is supplied to the AND circuit 511 through the AND circuit 505k and the OR circuit 505p, which are opened when the output of the level correction circuit 506 is at a low level and the transistor 505g is on, that is, after startup. .

When the output voltage Vcc of the constant voltage circuit 501 is equal to or higher than the operating voltage of the CPU at the time of starting the engine, as described above, the output of the voltage drop detection circuit 502 becomes a low level, and the AND circuits 520 to 524 become open. Therefore, the valve opening signal for the auxiliary fuel injector 7 output from the main arithmetic and control circuit 503 is supplied to the auxiliary fuel injector drive circuit 530 via the AND circuit 520 and the OR circuit 525, and the opening signal for each main fuel injector is The valve signal is sent to the main fuel injection valve drive circuit 5 via AND circuits 521 to 524 and OR circuits 526 to 529.
31-534.

The main calculation control circuit 503 calculates the valve opening time shown by the above-mentioned equation (3) every time the timing signal TDC is input during startup, and outputs the corresponding valve opening signal.
Sub and main fuel injection valve drive circuits 530 and 531~
534 to cause all fuel injection valves to inject simultaneously (Fig. 4e).

The main calculation control circuit 503 performs the simultaneous injection until the first cylinder discrimination signal CYL is input after starting. The first CYL signal after starting CYL ₁ (4th
_The timing signal TDC (4th
The number of operations of the main fuel injection valves is gradually decreased each time the input signal (b) in FIG. 4 is input (see e in FIG. 4). After inputting the second CYL signal CYL ₂ (FIG. 4a), the fuel injection valves corresponding to the respective timing signals TDC are sequentially opened and injection control is performed sequentially (FIG. 4e).

The valve opening time of the main fuel injection valve after startup until the transition to the sequential injection control is controlled to be the same as the valve opening time at startup, and the valve opening time, that is, the fuel injection amount, is controlled to be the same as the fuel injection amount during sequential injection. 1/4 of the amount, and the total for one cycle corresponds to the amount that should normally be injected. Therefore, the amount of fuel supplied to each cylinder during simultaneous injection does not become excessive.

By the way, when starting the engine, the constant voltage circuit 501
When the output voltage Vcc is lower than the operating voltage of the CPU, the output of the voltage drop detection circuit 502 becomes high level, AND circuits 511 to 515 are opened, and AND circuits 520 to 524 are closed. On the other hand, at the time of starting, the transistor 505f is turned on and the integrated voltage of the integrating circuit 505d is supplied to the comparator 505h, and the output of the comparator 505h is maintained until the integrated voltage is lower than the output voltage of the water temperature sensor 10 (Fig. 6e). It reaches a high level (Fig. 6g). The output of this comparator 505h is the AND circuit 5
While 05m is in the open state, the AND circuit 505
m to AND circuits 512 to 515 and OR circuit 5
26 to 529 to each main fuel injection valve drive circuit 5
31 to 534 (Fig. 6h). At the same time, the output of the AND circuit 505m is
5n, the auxiliary fuel injection valve drive circuit 5 via the OR circuit 505p, the AND circuit 511, and the OR circuit 525.
30 is also supplied.

Therefore, while the output of the comparator 505h is at a high level, the main fuel injection valves 6a to 6d and the auxiliary fuel injection valve 7
are controlled to open at the same time and for the same period of time. That is, all the fuel injection valves inject simultaneously. As described above, the valve opening time at this time is 1/4 of the valve opening time of the main fuel injection valve during normal operation.

Therefore, the constant voltage power supply circuit 50 is synchronously activated during startup.
Even if the output voltage Vcc of 1 is lower than the operating voltage of the CPU, the valve opening time is 1/4, so excess fuel will not occur.

Furthermore, when the output voltage Vcc of the constant voltage circuit 501 drops below the operating voltage of the CPU due to some abnormality during operation after the engine is started, the transistor 505g is turned on and the integrated voltage of the integrating circuit 505e is supplied to the comparator 505h. Comparator 505
The output of h remains at a high level while the integrated voltage is lower than the water temperature sensor output voltage (Fig. 6 f) (Fig. 6 g).
(indicated by a dashed line). The output of this comparator 505h is output from the AND circuit 505m while the AND circuit 505m is in an open state (shown by a broken line in FIG.
Each main fuel injection valve drive circuit 53 via 6 to 529
1 to 534, and each main fuel injection valve 6a to 6
d is injected simultaneously. Main fuel injection valve 6 at this time
The injection times a to 6b are approximately equal to the valve opening time during normal operation.

On the other hand, the output pulse signal of the one shot circuit 505b is the output pulse signal of the AND circuit 5 which is in an open state during normal operation.
05k, is supplied to the auxiliary fuel injection valve drive circuit 530 via the OR circuit 505p, the AND circuit 511, and the OR circuit 525, and is supplied to the one shot circuit 505.
While the output pulse b is at a high level (FIG. 6c), the auxiliary fuel injection valve 7 is controlled to open. The valve opening time at this time, that is, the pulse time of the one-shot circuit 505b, is set to be approximately equal to the valve opening time of the auxiliary fuel injection valve during the normal operation.

Therefore, even if the output voltage Vcc of the constant voltage circuit 501 drops below the operating voltage of the CPU during operation, the engine can continue to operate.

Note that the non-inverting input terminal of the comparator 505h receives other signals, for example, instead of the output signal of the water temperature sensor 11.
A parameter signal such as a throttle valve opening signal representative of the intake air amount or an intake pipe absolute pressure signal may be used.

Furthermore, when the low voltage operation circuit 505 is activated, the opening time of the auxiliary fuel injection valve after engine startup is made constant regardless of the engine water temperature.
Even after starting, the valve opening time may be set in accordance with the engine water temperature, a parameter value representative of the intake air amount, etc.

As explained above, according to the present invention, the central processing unit of the electronic control unit receives a cylinder discrimination signal that is generated once per cycle of the engine at a predetermined position of the crankshaft of the engine, and a cylinder discrimination signal that is generated at a predetermined position of the crankshaft of the engine. The timing signal shown in FIG. In a fuel supply control method for a multi-cylinder internal combustion engine, all fuel injection valves are opened simultaneously every time a cylinder discrimination signal is input, and thereafter, after a cylinder discrimination signal is input, fuel injection valves corresponding to each timing signal are sequentially opened. When the operating voltage does not reach the predetermined voltage, a low voltage operating circuit independent from the central processing unit is operated in place of the central processing unit to inject all fuel at each timing signal in accordance with the timing signal. It is characterized by opening the valves at the same time, so
In other words, if the central processing unit detects a voltage that does not allow it to operate normally, a circuit that operates independently of the central processing unit even at a low voltage, that is, a complex circuit that requires high voltage to perform sequential injection. Instead, a very simple and compactly designed low-voltage operation circuit that performs simultaneous injection for each timing signal is switched and activated, and all fuel injection valves are opened for each timing signal in response to the timing signal. As a result, it is possible to obtain good startability and to continue stable engine operation even when the battery voltage decreases during operation.

Furthermore, since the low-voltage operating circuit sets the opening time of the fuel injection valve according to at least one engine operating parameter (water temperature, throttle valve opening, absolute pressure in the intake pipe, etc.), the battery voltage This makes it possible to inject fuel according to the operating condition even when the engine temperature is low, allowing for more stable engine operation.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of a fuel supply control device to which the present invention is applied, FIGS. 2 and 3 are flowcharts showing the procedure of the control method of the present invention, and FIGS. A timing chart showing the operation of the fuel supply control method based on the flowchart in FIG.
FIG. 5 is a block diagram showing an example of the internal configuration of the electronic control unit (ECU) shown in FIG. 1, and FIG. 6 is a timing chart of output signals of each part shown in FIG. 1... Internal combustion engine, 5... Electronic control unit, 6, 6a to 6d... Main fuel injection valve, 7
...Auxiliary fuel injection valve, 10...Water temperature sensor, 11...
...Engine speed sensor, 12...Cylinder discrimination sensor, 16...Key switch, 17...Battery,
502... Electricity drop detection circuit, 503... Main calculation control circuit, 505... Low voltage operation circuit.

Claims (1)

[Scope of Claims] 1. A cylinder discrimination signal, which is generated once per engine cycle at a predetermined position of the crankshaft of the engine, and a timing signal indicating the predetermined position of the crankshaft are sent to the central processing unit of the electronic control unit. The operating voltage that is input and supplied to the central processing unit is detected, and when the operating voltage is equal to or higher than a predetermined voltage, the timing signal is detected every time the timing signal is input after starting until the cylinder discrimination signal is input for the first time. In a fuel supply control method for a multi-cylinder internal combustion engine, all fuel injection valves are opened simultaneously, and after a cylinder discrimination signal is input, fuel injection valves corresponding to each timing signal are sequentially opened,
When the operating voltage does not reach the predetermined voltage, a low voltage operating circuit independent from the central processing unit is operated in place of the central processing unit to inject all fuel at each timing signal in accordance with the timing signal. A fuel supply control method for a multi-cylinder internal combustion engine characterized by opening valves simultaneously. 2. The internal combustion supply control method for a multi-cylinder engine according to claim 1, wherein the low voltage operating circuit sets the opening time of the fuel injection valve according to at least one engine operating parameter. .