JPH0544548B2 - - Google Patents

Description

[Detailed description of the invention]

Object of the Invention [Field of Industrial Application] The present invention relates to an electronic fuel injection control device, and more specifically, an electronic fuel injection control device that realizes suitable fuel injection control even when the power supply voltage drops during starting of an internal combustion engine. Regarding. [Prior Art] In recent years, electronic control of internal combustion engines has progressed, and the amount of fuel supplied to the internal combustion engine is calculated by a microcomputer based on the operating conditions of the internal combustion engine, and the opening time of the fuel injection valve is controlled. Electronic fuel injection controls (EFI) have become widespread. In such an electronic fuel injection control device, the microcomputer that calculates the fuel injection time, etc. must naturally operate normally, but since it is an electronic device, it is inevitably affected by power supply voltage fluctuations. Particularly during startup, the power supply voltage can drop considerably as the starter drives a large load, and it is not possible to guarantee the operation of the microcomputer when the battery, which is the power supply, is weakening or at low temperatures. In some cases, the voltage dropped to levels that could not be used. Therefore, in internal combustion engines equipped with conventional electronic fuel injection control devices, a separate system of fuel injection valves (start injectors, STJs) that operate stably even at low voltage is used separately from this electronic fuel injection control device.
is installed in the intake pipe and combined with a bimetallic time switch (TZS) to ensure that fuel is injected for a certain period of time at startup, as well as backup means that stores the fuel injection time at startup in advance. When the power supply voltage falls below a predetermined voltage, the output of the backup means is used instead of the calculation result of the microprocessor to perform fuel injection (see ``Fuel Injection for Internal Combustion Engines'' in Japanese Unexamined Patent Publication No. 58-217737). A variety of devices have been proposed, including a control device. [Problems to be Solved by the Invention] Against the background of the prior art, the problems to be solved by the present invention are as follows. (1) When a start injector (STJ) is used to control fuel injection during startup, electrical and fuel systems must be prepared that are separate from the system that performs normal fuel injection, resulting in a complicated device configuration. This resulted in problems such as a decrease in reliability as a whole, an increase in the number of manufacturing steps, and a rise in costs. Further, the amount of fuel injection is determined primarily by the start timer, and it is difficult to precisely control the starting conditions of the internal combustion engine, such as the cooling water temperature and the number of fuel injections. (2) If backup means is provided and the correctness of the calculation output of the microprocessor cannot be guaranteed, even if fuel injection is performed using the output of the backup means, backup means must be provided, and the same as in (1) must be provided. This is causing problems. Also,
If the contents of the backup means are fixed, precise control cannot be performed as described above, and on the other hand,
If the contents of the backup means can be corrected based on the operating conditions of the internal combustion engine when the microprocessor is normal, if the microprocessor goes out of control due to a voltage drop, etc., incorrect values can be corrected. There was also a problem that the code could be rewritten, which could cause malfunctions. (3) Since the maximum load on the starter occurs when any one cylinder of the internal combustion engine is in the late stage of the compression stroke, the battery voltage pulsates accordingly when the internal combustion engine is started. Therefore, for a microprocessor, instead of always being in a state where the voltage can operate normally or not, it changes the voltage range in which it can operate normally and the voltage in which it cannot, depending on the pulsation. The range may be repeated. As a result, once the voltage reaches a voltage that does not guarantee normal operation and the entire microcomputer is reset, the microcomputer will start up from its initial state even if the power supply voltage returns to normal. Therefore, after initial processing, various operating conditions such as the rotation speed of the internal combustion engine and the temperature of the cooling water are read, and the
The fuel injection amount is calculated and the fuel injection is finally performed, but the power supply voltage drops again and before or during the fuel injection,
The reset may take a long time, resulting in the problem that the necessary fuel injection amount cannot be secured at the time of starting. (4) Even if the fuel injection control described in (3) above is completed in time, in this case, each time a reset is applied, the microprocessor starts from calculating the fuel injection amount, so it has already been It is not possible to remember the amount of fuel injection that has been performed, and fuel injections are performed one after another. As a result, if the ignition system malfunctions, the spark plug will become stuck, and even if the ignition system recovers,
There was a problem in that ignition could no longer be performed and the internal combustion engine could no longer be started. Furthermore, the proportion of fuel injected into the intake pipe during startup that is vaporized and sucked into the cylinders is largely influenced by the temperature of the internal combustion engine. When the internal combustion engine is completely cold, most of the injected fuel adheres to the inner wall of the intake pipe, intake valves, etc., and the proportion of fuel that is sucked into each cylinder decreases. Therefore, in such a case, the total amount of fuel injection at the time of startup must be increased, but in a situation where the microprocessor is reset every time, it is impossible to control the total amount of fuel injection. I couldn't do it. (5) In order to deal with these problems, a method could be considered in which the total amount of fuel injection at startup determined by the cooling water temperature of the internal combustion engine, the cumulative value of the fuel injection time, etc. are stored in the backed up memory. ,
If the microprocessor goes out of control due to voltage drop, noise, etc., the data may be rewritten, which may even lead to malfunctions, so this has not been a complete solution. SUMMARY OF THE INVENTION Therefore, it is an object of the present invention to provide an electronic fuel injection control device that solves the problems (1) to (5) above and can perform suitable fuel injection control at startup with a simple configuration. Structure of the Invention [Means for Solving the Problems] The means taken to solve the above problems in order to achieve the above object are summarized as follows, as shown in Figure 1. . That is, an operating condition detection means M2 that detects operating conditions including the cooling water temperature of the internal combustion engine M1, a fuel injection means M3 that injects fuel into the internal combustion engine M1, and a temporary memory that stores information regarding at least fuel injection at startup. Means M4 and microprocessor M
5, the microprocessor M5 calculates the fuel injection amount based on the information stored in the temporary storage means M4 and the detected operating condition of the internal combustion engine M1, and In an electronic fuel injection control device, the electronic fuel injection control device includes: a fuel injection control means M6 that controls main fuel injection in synchronization with the rotation of the internal combustion engine M1; and a power supply voltage monitoring means M that monitors the state of the power supply voltage.
7, and a rewriting inhibiting means for prohibiting rewriting of the contents of the temporary storage means M4 when the power supply voltage monitoring means M7 detects that the voltage has fallen below a predetermined voltage that guarantees the operation of the microprocessor M5. M
8, and the fuel injection control means M6 is configured to control the internal combustion engine M.
1, when the monitored power supply voltage returns from below the predetermined voltage to above the predetermined voltage, the starting fuel injection is started, and when the starting voltage becomes below the predetermined voltage, the starting fuel injection is stopped. The microprocessor M5 performs control to cumulatively store the fuel injection amount during that time in the temporary storage means M4, and the cumulative fuel injection amount is determined based on the cooling water temperature of the internal combustion engine. This is the configuration of an electronic fuel injection control device characterized in that the fuel injection at startup is controlled until the fuel injection reaches a predetermined value. Here, the operating condition detection means M2 detects the internal combustion engine M1.
It detects various operating conditions including the cooling water temperature Thw, such as the rotational speed Ne of the internal combustion engine M1, the intake air amount Q, and its temperature Ta, etc., and is necessary due to the control requirements of the internal combustion engine used. Just use what you have. The fuel injection control means M6, which includes a microprocessor M5 and a temporary storage means M4, is realized by a well-known microcomputer consisting of one chip or several elements.
5. In addition to the temporary storage means M4, a configuration including analog or digital input/output ports, a timer, a counter, etc. may be considered as required for control. The microprocessor M5 is responsible for calculations, data exchange, etc., and is a central processing unit (CPU).
Although it is also called, normally, the amount of fuel injection to be performed, etc. is determined from the operating conditions of the internal combustion engine M1 detected by the above-mentioned operating condition detection means M2 and the information regarding the fuel injection stored in the temporary storage means M4. Then, the fuel injection means M3, for example, an electromagnetic fuel injection valve, is opened and closed to control fuel injection. The temporary storage means M4 temporarily stores data and is used for writing and reading data by the microprocessor M5. The total amount of fuel injection at startup determined by the cooling water temperature of the microprocessor M
The information necessary for controlling the fuel injection at startup, such as the cumulative value of the fuel injection amount at startup written in step 5, is stored. For example, CMOS type static RAM can be used, and there are some that can hold contents over a wide voltage range from several volts to several tens of volts. The power supply voltage monitoring means M7 is the fuel injection control means M
This monitors the power supply voltage supplied to the microprocessor M5, and monitors the power supply voltage supplied to the microprocessor M5 at various preset voltages, such as a predetermined voltage that guarantees the operation of the microprocessor M5 up to this point, or a predetermined voltage that guarantees the operation of the microprocessor M5 up to this point. It is configured to detect a predetermined voltage, which is guaranteed if it is a voltage, and output it to a rewriting inhibiting means M8, a fuel injection controlling means M6, etc., which will be described later. As mentioned above, the rewriting inhibiting means M8 inhibits rewriting of the contents of the temporary storage means M4 when the power supply voltage falls below a predetermined voltage that guarantees the operation of the microprocessor M5 up to this point.
Due to problems such as runaway of microprocessor M5 and bit loss during data exchange, temporary storage means M
This protects the contents of Section 4. Although the specific configuration depends on the mode of the temporary storage means M4, a circuit configuration or the like is adopted in which the write control signal line of the temporary storage means M4 is not activated. [Function] The electronic fuel injection control device of the present invention having the above-mentioned configuration includes a power supply voltage monitoring means to check whether a predetermined power supply voltage at which the microprocessor M5 of the fuel injection control means M6 can operate normally is secured. Detected by M7, and below that voltage, rewriting prohibition means M8
It is prohibited to rewrite the contents of the temporary storage means M4. Moreover, when the power supply voltage once drops below a predetermined voltage and then returns to above this voltage, starting fuel injection is started, and when the voltage drops below this voltage, starting fuel injection is stopped, and further starting operations, such as starting a starter, are performed. Control is performed to accumulate and store the fuel injection amount from the time when the engine is turned on in the temporary storage means M4, and the cumulative value of the stored fuel injection is controlled to be the cooling water temperature of the internal combustion engine M1. The process continues until a predetermined value determined based on the above is reached. Therefore, due to the load of the starter etc. at the time of starting,
Even if the power supply voltage pulsates across the predetermined normal operating voltage of the microprocessor M5, as soon as the power supply voltage returns to a voltage that guarantees the normal operation of the microprocessor M5, the microprocessor M5
performs fuel injection at startup, and controls the total amount of fuel injection in accordance with the cooling water temperature of internal combustion engine M1. [Example] Hereinafter, an example of the present invention will be described in detail based on the drawings. FIG. 2 is a schematic configuration diagram showing a schematic configuration of an internal combustion engine and its peripheral devices as an embodiment of the present invention;
The figure is a block diagram showing the configuration of an electronic control circuit as fuel injection control means. In the figure, 1 is a 4-stroke, 4-cylinder internal combustion engine, 2 is an electronic control circuit as fuel injection control means, and 3 is a battery as a power source. An air cleaner 5 is connected to the intake pipe 4 of the internal combustion engine 1 from upstream.
An air flow meter 7, an intake temperature sensor 9, a throttle valve 11, an idle switch 12, etc. are provided, and the intake air is injected together with fuel injected from an electromagnetic fuel injection valve 17 as a fuel injection means provided in a branch pipe 15. The mixture becomes a mixture and is sucked into a cylinder (not shown). On the other hand, an O2 sensor 2 is installed in the exhaust pipe 19 of the internal combustion engine 1 to detect the oxygen concentration in the exhaust gas composition.
1 is provided. Furthermore, 23 is an igniter, 25 is an igniter 2
The distributor 25 distributes the high voltage generated in the internal combustion engine 1 to the spark plugs (not shown) of each cylinder in synchronization with the rotation of the crankshaft 27 of the internal combustion engine 1. The distributor 25 receives the cylinder discrimination signal G1 of the internal combustion engine 1. and a rotational speed signal Ne.
Further, 29 is an ignition switch that connects the battery 3 to the electronic control circuit 2, and 31 is an ignition switch that partially operates in conjunction with the ignition switch 29 to connect the starter motor 3.
2 is a starter switch that turns on and off; 33 is a water temperature sensor that detects the temperature of the cooling water of the internal combustion engine 1;
It is. The electronic control circuit 2 includes a microcomputer 50
The core includes an analog input circuit 52, an A/D conversion circuit 53, a digital input circuit 54, a backup circuit 56, a signal switching circuit 58, a power supply circuit 60,
It is composed of output signal buffers 62 and 63. The analog input circuit 52 of the electronic control circuit 2 is
Intake air amount as signal from air flow meter 7
Us, the cooling water temperature Thw of the internal combustion engine 1 as a signal from the water temperature sensor 33, and the intake temperature Ta as a signal from the intake temperature sensor 9 are input, and these signals are input by the A/D conversion circuit 53 at the next stage. The voltage +B of the battery 3 is sequentially A/D converted and taken into the microcomputer 50. On the other hand, the digital input circuit 54 receives the cylinder discrimination signal G1 and rotational speed signal Ne generated by the distributor 25, the lean/rich signal Ox as a signal from the O2 sensor 21, and the information that the throttle valve 11 is fully closed. The signal Idle from the idle switch 12 indicating the state and the signal STA indicating the state of the starter switch 31 are input to the microcomputer 5.
0 to the backup circuit 56. The power supply circuit 60 inputs the battery voltage +B through the ignition switch 29 and the backup voltage Batt without going through the ignition switch 29, and outputs the voltage to the microcomputer 5.
0 and another constant voltage Vc to be supplied to other circuits.
In addition, the power supply circuit 60 monitors the voltage of the constant voltage Vsub and generates the signal wi, and clears a watchdog that notifies the microcomputer 50 by software that the microcomputer 50 is operating normally. Based on signal wdc,
It also operates as a power supply sequence for generating an initial signal for the microcomputer 50, which will be described later. As shown in FIG. 4, the microcomputer 50 has a well-known microprocessor (MPU) 70, ROM 71, RAM 73, input port 74, output port 76, clock generation circuit 78, common bus 79, etc. integrated into one chip. It is a one-chip microcomputer, and in particular, in this embodiment, it has an address decoder 81 and an R-S flip-flop 8.
2. Inverter 83, gated bus driver 84
It also has a built-in wi signal detection circuit 86 consisting of the following.
Note that the clock generation circuit 78 is an external crystal oscillator 8.
8 to generate the basic operating clock for the MPU 70. The microflosser 70 reads the operating conditions of the internal combustion engine 1 through the input port 74, and
The ignition timing, fuel injection amount, and injection timing are calculated. Then, through the output port 76, the A/D
In addition to the control signal of the conversion circuit 53, the ignition timing control signal ig is sent to the backup circuit 56, and the signal switching circuit 5
Fuel injection control signals τ1, τ2 are supplied to power supply circuit 6.
A watchdog clear signal wdc is output at 0, respectively. Here, the fuel injection control signal τ1 is the internal combustion engine 1.
The fuel injection control signal τ2 is a signal that controls the normal main fuel injection that is output in synchronization with the rotation of the engine, and the fuel injection control signal τ2 is a signal that controls the starting fuel injection performed in the present invention. The handling of the fuel injection control signal τ2 will be explained in detail later based on a flowchart. The backup circuit 56 is a circuit for supplementing control when the microcomputer 50 stops operating normally, and operates as follows. The microcomputer 50 is controlled by the microprocessor 70, and when the internal combustion engine 1 is in operation, the ignition timing control signal ig is determined based on the rotational speed Ne of the internal combustion engine 1, regardless of whether it is starting or not. It is output at predetermined intervals. Therefore, when the ignition timing control signal ig is no longer output for a predetermined period of time, the microcomputer 50 determines that there is an abnormality, and outputs the ignition signal at a predetermined timing based on the cylinder discrimination signal G1 and the rotational speed signal Ne. IGt is output to the igniter 23 via the buffer 62. At the same time, the microcomputer 50 outputs a predetermined fuel injection amount control signal τ3 as a signal indicating that there is an abnormality.
It is output to the signal switching circuit 58 along with fail. The signal switching circuit 58 normally receives the fuel injection control signals τ1 and τ2 output from the microcomputer 50 and outputs the fuel injection signal τp for opening and closing the electromagnetic fuel injection valve 17 via the buffer 63. When the backup circuit 56 detects an abnormality in the microcomputer 50 and outputs a signal, the electromagnetic fuel injection valve is 17. FIG. 5 shows an example in which the signal switching circuit 58 is constructed of known logic gates. An example of the control of the internal combustion engine 1 performed in the above configuration is shown in the time chart of FIG. Next, the configuration and function of the power supply circuit 60 will be explained based on the circuit diagram of FIG. 7, and the function of the wi signal detection circuit 86 in the microcomputer 50 will also be described. Mention an example. As shown in FIG. 7, the power supply circuit 60 includes a constant voltage output section 93 that generates a constant voltage Vsub supplied to the microcomputer 50 and a constant voltage Vc supplied to circuits other than the microcomputer 50;
It consists of a wi signal output section 95 that monitors the voltage of Vsub, and an initial signal generation circuit 97 that generates an initial signal in cooperation with the watchdog clear signal wbc of the microcomputer 50. The constant voltage output section 93 includes a regulator 101 that generates a constant voltage Vc using battery voltage +B as a power source.
and a regulator 102 that generates a constant voltage Vsub using the battery voltage Batt as a voltage source that does not go through the ignition switch 29. The wi signal output section 95 is a circuit that monitors the voltage of the constant voltage Vsub using the reference voltage Vd1 formed internally by the operational amplifier OP1, and is formed by dividing the voltage by resistors R11, R12, and R13. By using the hysteresis, the output signal becomes low active when the constant voltage Vsub becomes lower than the judgment voltage V2, and the judgment voltage higher than the voltage V2 is set to low active.
It is configured to be set to high level when it reaches V1 or higher. Here, the judgment voltage V2 is set as a voltage at which the MPU 70 in the microcomputer 50 can judge that its own operation is normal up to this voltage, and on the other hand, the judgment voltage V1 is set as a voltage at which the MPU 70 in the microcomputer 50 can judge that its own operation is normal. It is set as a voltage that the MPU 70 can judge by itself to normally restart control of fuel injection, etc., and by providing a listeresis voltage (ΔV) to both, it is possible to prevent chattering during operation near the boundary. Preventing occurrence. In addition, the constant voltage Vsub
The fluctuation occurs when the voltage Batt of the battery 3 decreases beyond the capacity of the regulator 102. As mentioned in the explanation of the input/output signals of the microcomputer 50, the initial signal generation circuit 97 is activated when the MPU 70 goes out of control due to a drop in power supply voltage, noise, etc.
When Vsub drops to a voltage where the operation of the MPU 70 can no longer be guaranteed, an initial signal is output to stop the microcomputer 50, and this initial signal also serves as the initial signal when the electronic control circuit 2 is powered on. There is. The output signal of the above-mentioned wi signal output section 95 is sent to the wi signal detection circuit 86 in the microcomputer 50.
It is connected to the S terminal of the R-S flip-flop 82. Since the output of the inverter 83 is normally at a high level, once the signal becomes low active, the R-S flip-flop 82 is set and its output Q is at a low level (corresponding to signal O).
is set to . The MPU 70 outputs the address set to the wi signal detection circuit 86, opens the gated bus driver 84 via the address decoder 81, and can read the state of the output Q of the R-S flip-flop 82. Alternatively, data can also be written to the R terminal of the R-S flip-flop 82 via the address decoder 81. The truth table of the R-S flip-flop 82 is as follows.

[Table] Here, Qn-1 indicates that the output Q maintains the state at the time immediately before the state of the R and S terminals changed. Therefore, once the signal becomes low level, even if the MPU 70 writes level 1 to the wi signal detection circuit 86, the state of the output Q remains low level. However, constant voltage
When Vsub becomes equal to or higher than the determination voltage V1 and the signal becomes a high level, the state of the output Q is inverted by the write operation from the MPU 70 and becomes a high level. Note that the address of the wi signal detection circuit 86 that is read and written by the MPU 70 is hereinafter referred to as a WI port. The output Q of the R-S flip-flop 82 is RAM
When this signal Q becomes low level, the write signal line in the RAM 73 is inactivated, and no data can be written to the RAM 73. This is RAM7
Since the data write control signal line in 3 is low active (writing is possible when it is low level), when the signal Q becomes low level, the write terminal R/ of RAM 73 is This can be easily realized by a configuration in which the voltage is set equal to the power supply voltage Vc. Regarding the processing performed by the MPU 70 of the microcomputer 50 in the electronic fuel injection control device 2 of this embodiment having the above hardware configuration,
The explanation will be based on the flowchart shown in FIG.
The MPU 70 repeatedly executes an interrupt routine (started every 4 msec) shown in the flowchart of FIG. 9 as control of starting fuel injection. First, the processing at each step will be explained. Step 180: Determine whether the starter 32 is being driven or not based on the state of the signal STA. Step 190: A process of reading the cooling water temperature Thw of the internal combustion engine 1 from the water temperature sensor 33 is performed. Step 200: Cooling water temperature read in step 190
According to Thw, a process is performed to obtain values t1 and t2 from a map, an example of which is shown in FIG. 10, for example. Here, the value t2 is a value corresponding to the upper limit value of the total amount of fuel injected in one starting operation (cumulative injection amount upper limit value), and even if the internal combustion engine 1 does not reach the combustion cycle, the spark plug This is the upper limit value set for fuel injection at startup to prevent fogging, etc., and to avoid unnecessary fuel injection. On the other hand, the value t1 is determined to be two times larger than the value t2, and the value t1 is determined based on the necessity of processing using the variable CTIME in the program flow described later. Note that the values t1 and t2 are stored in certain areas within the memory 73. Steps 210 and 220: Write a value 1 to the WI port, that is, the wi signal detection circuit 86. Steps 230 and 240: Determine whether the value of the WI port is 1 or not. Step 250: Determine whether the value of the variable CTIME is greater than or equal to t1. Step 260: Determine whether the value of the variable CTIME is less than t2. Furthermore, at step 250, the value t1
is set as a value that is two or more larger than the value t2. Step 270: Processing is performed to set the variable CTIME to the value t1. Step 280: Variable used as counter
Performs processing to set CTIME to 0. Step 290: Increment the variable CTIME by 1, ie, CTIME←CTIME+1. Step 300: A process is performed to change or maintain the output fuel injection control signal τ2 in the on state. Step 310: Processing is performed to change or maintain the output fuel injection control signal τ2 in the OFF state. The control by this interrupt routine that performs the above processing and judgment is executed in the following order. (1) First, start from step 180, or turn on the ignition switch 29 to drain the battery.
Immediately after supplying the voltage +B to the electronic control circuit 2, the starter switch 31 is not yet closed, so the starter 32 is not turned on, and the determination at step 180 is "NO".
The process then proceeds to step 190. In step 190, the cooling water temperature Thw of the internal combustion engine 1 is read, and in the following step 200, a value t2 is determined as the cumulative injection amount upper limit value based on the cooling water temperature Thw, and a value t1 larger than the value t is determined based on processing requirements. It is done. After writing 1 to the WI port in the following step 210, the value t1 is written to the variable CTIME in step 270, and in step 310, the fuel injection control signal τ2 is turned off,
Exit to RTN and end the first execution of this interrupt routine. (2) Eventually, when the starter switch 31 is closed, the starter 32 receives power from the battery 3 and begins to rotate, driving the internal combustion engine. When this interrupt routine is started, step 180 is executed.
The judgment is “YES” and the process goes to step
Proceed to 230, WI port = 1? A judgment will be made. Since the value 1 was written to the WI port in the previous processing prior to starting the current interrupt routine, the constant voltage Vsub, which is the power source for the microcomputer 50, decreases due to the addition of the load of the starter 32. If not, the value of the WI port remains 1, and if the constant voltage Vsub is below the judgment voltage V2, the value of the WI port is 0.
It is becoming. If the battery 3 has a sufficient capacity and the constant voltage Vsub does not drop, the determination at step 230 is ``YES'' and the process proceeds to step 260, where it is determined that CTIME<t2. The value of the variable CTIME is set at step 270 in the first interrupt routine processing.
Since it is set to t1, the judgment at step 260 is "NO", and the process moves to step 310, where the fuel injection control signal τ2 is kept in the OFF state and exits to RTN, ending this interrupt routine. do. Therefore, in this case, starting fuel injection, which will be described later, is not performed, and fuel is supplied by normal main fuel injection. (3) On the other hand, when the load of the starter 32 is applied due to the battery 29 being weak, etc., the voltage +B of the battery 29 decreases significantly, and the constant voltage Vsub to the microcomputer 50 also falls below the judgment voltage V2. If , step 230
Judgment is "NO" (WI port = 1 does not hold)
The process then proceeds to step 220. step
At 220, the value 1 is written to the WI port, and at the following step 240, it is again determined whether the WI port is 1 or not. If the signal is at a low level, the value of the WI port will not be updated to 1 even if the MPU 70 writes the value 1. Therefore, the value of the WI port will not be updated to 1 even if the MPU 70 writes the value 1. Therefore, the value of the WI port is not updated in step 240 until the constant voltage Vsub falls below the judgment voltage V2 and then becomes equal to or higher than the judgment voltage V1. The determination is "NO" and the process proceeds to step 310-RTN as described.
After the load of the starter 32 pulsates and the constant voltage Vsub exceeds the judgment voltage V1, step 230 is performed.
- In the processing and judgment at step 220, the value of the WI port becomes 1, and the judgment at step 240 becomes "YES". This situation is shown in FIG. In other words, when the signal becomes low active, the state of the WI port becomes low level, and the signal
First MPU70 after wi becomes high level
It returns to high level by writing data 1. (4) If the judgment in step 240 is “YES”, that is, WI
When port=1, the process proceeds to step 250,
It is determined whether the value of the variable CTIME is greater than or equal to t1. The value of the variable CTIME is initially
Since the value set as the value t1 remains unchanged at step 270, the determination at step 250 is "YES" and the process proceeds to step 280. In step 280, the variable
The following steps set the value of CTIME to 0:
At 300, the fuel injection control signal τ2 is turned on.
Exit to RTN and end this interrupt routine.
When the output of the fuel injection control signal τ2 is turned on, the output signal τp of the electronic control circuit 2 becomes active, and the electromagnetic fuel injection valve 17 is opened. (5) Under the above conditions, when this interrupt routine is started next time, the value of the WI port will be 1 until the constant voltage Vsub decreases again and falls below the judgment voltage V2, so the step 230 will be executed. The determination is ``YES'', and in step 260 it is determined whether the variable CTIME is less than the value t2. The value of the variable CTIME is set to 0 in step 280, and is incremented by 1 each time step 290 is executed, so the judgment up to step 260 is ``YES'' until this value reaches t2.
Then, steps 290 and 300 are subsequently performed to continue fuel injection based on the fuel injection control signal τ2. (6) When the constant voltage Vsub falls below the judgment voltage V2 again,
The same control as in (3) above is performed, fuel injection is stopped, and then the constant voltage Vsub is changed to the judgment voltage V1 again.
In the above case, the same control as in (5) above is performed. (7) When the value of the variable CTIME reaches the value t2 as a result of repeated incrementing, step 260 is executed.
The judgment is "NO", and in step 310, the fuel injection control signal τ2 is turned off and the RTN
This interrupt routine ends. Therefore, when the cumulative value of the fuel injection at startup reaches the amount determined by the value t2, which is a 4 msec interrupt routine here, the fuel injection amount corresponds to the fuel injection time of 4 x t2 msec, then further fuel injection is performed. is not carried out regardless of the state of constant voltage Vsub. In the overall control described above, the RAM 73 in the microcomputer 50 is configured to protect the contents by prohibiting writing when the constant voltage Vsub becomes lower than the determination voltage V2, as described above. The battery voltage +
Even if B pulsates, the value of the variable CTIME is saved. An example of fuel injection control performed by repeatedly executing this interrupt routine at the time of starting the internal combustion engine 1 is shown in the timing chart of FIG. That is, fuel injection at startup is performed while using the value of the variable CTIME as a counter from when the constant voltage Vsub becomes equal to or higher than the determination voltage V1 until it becomes less than the determination voltage V2 (section in FIG. 12). variable
It is stopped when the value of CTIME becomes t2 or more (section). Normal main fuel injection is performed separately from this, and once the constant voltage Vsub is established, it is performed by normal fuel injection control (section). In this embodiment configured as above,
Constant voltage that is the power supply voltage of the microprocessor 70
The state of Vsub is monitored by the wi signal output section 95, and when the voltage falls below the voltage that guarantees the operation of the microprocessor 70 (determination voltage V2 in this case), the contents of the RAM 73 are saved and the operation of the microprocessor 70 is resumed. When the voltage reaches a level that does not cause any problem in restarting the engine (determination voltage V1 in this case), fuel injection specific to starting is executed. Therefore, even if the constant voltage Vsub fluctuates, including a voltage range in which the operation of the microprocessor 70 cannot be guaranteed during startup, fuel injection at startup starts immediately when the determination voltage V1 or higher is reached. Therefore, reliable fuel injection at startup can be expected, and the intake of combustible mixture into the cylinders is ensured. Moreover, the starting fuel injection is performed up to the upper limit of the total amount of starting fuel injection determined based on the cooling water temperature Thw of the internal combustion engine 1, and the cumulative value of the starting fuel injection is stored in the RAM 73 as a variable CTIME. Therefore, the total amount of fuel injection at startup can be controlled according to the state of the internal combustion engine 1. As a result, even when the internal combustion engine 1 is completely cold, a sufficient amount of fuel can be injected.
Problems such as those caused by the engine not being ignited do not occur, and the startability of the internal combustion engine 1 is sufficiently ensured. Furthermore, even if the constant voltage Vsub falls further below the judgment voltage V2, causing the signal in the power supply circuit 60 to be output and the microcomputer 50 is reset, the constant voltage Vsub will recover and the judgment voltage will be reduced.
If it is equal to or higher than V1, fuel injection at startup is executed using the fuel injection control signal τ2 without waiting for the main fuel injection, which is performed by calculating the fuel injection time from the rotational speed Ne of the internal combustion engine 1 and other parameters.
When the starter 32 can rotate, it is possible to ensure that fuel is drawn into each cylinder of the internal combustion engine 1. Furthermore, in this embodiment, only a few electrical circuits are added, and fuel injection is always controlled under a single microprocessor 70, and the start injector, its fuel system, etc. It is possible to perform reliable fuel injection at startup with a simple configuration. In addition, in this example, the constant voltage Vsub is the constant judgment voltage.
When the microprocessor 70 becomes unable to output the ignition timing control signal ig due to V2 or lower,
The backup circuit 56 controls the ignition timing and fuel injection of the internal combustion engine 1, and it can be said that the startability of the internal combustion engine 1 is almost perfect in the voltage range in which the starter 32 is driven. . Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments in any way.
It goes without saying that the invention can be implemented in various ways without departing from the spirit of the invention. Effects of the Invention As detailed above, according to the electronic fuel injection control device of the present invention, reliable fuel injection at the time of starting can be achieved without the need for a start injector or its fuel system. Yes, internal combustion engine 1
This has the excellent effect of ensuring sufficient startability. In addition, since the total amount of fuel injected at startup is controlled according to the temperature of the internal combustion engine's cooling water, not only can sufficient fuel be injected depending on the state of the internal combustion engine, but also if the internal combustion engine In the case where the engine is not ignited, unnecessary fuel injection is not continued, and fogging of the spark plug and waste of fuel can be prevented. Furthermore, since the configuration can be simplified, problems such as reliability of the device and trouble and cost of the manufacturing process are also improved.

[Brief explanation of the drawing]

FIG. 1 is a basic configuration diagram of the present invention, FIG. 2 is a schematic configuration diagram showing the configuration of an internal combustion engine and its peripheral devices as an embodiment of the present invention, and FIG. 3 is a configuration diagram of the electronic control circuit 2. 4 is a block diagram showing the configuration of the microcomputer 50, FIG. 5 is a logic circuit diagram showing an example of the configuration of the signal switching circuit 58,
FIG. 6 is a timing chart showing an example of control of ignition timing and fuel injection by the backup circuit 56, FIG. 7 is a circuit diagram showing the configuration of the power supply circuit 60, and FIG. 8 is an example of a configuration for inhibiting writing to the RAM 73. Circuit diagram, Fig. 9 is a flowchart of a 4 msec interrupt routine showing a control example in the embodiment, Fig. 10 is a map for determining the upper limit value of the cumulative injection amount from the cooling water temperature Thw, and Fig. 11 explains the state of the WI port. Timing Chart FIG. 12 is a timing chart showing an example of fuel injection control in the embodiment. 1... Internal combustion engine, 2... Electronic control circuit, 3...
Battery, 17... Solenoid fuel injection valve, 29...
Ignition switch, 31... Starter switch, 32... Starter, 50... Microcomputer, 60... Power supply circuit, 70... Microprocessor (MPU), 73... RAM, 82...
R-S flip-flop, 86...wi signal detection circuit, 95...wi signal output section.

Claims (1)

[Scope of Claims] 1. Operating condition detection means for detecting operating conditions including cooling water temperature of the internal combustion engine; Fuel injection means for injecting fuel into the internal combustion engine; and a temporary storage device for storing at least information regarding fuel injection at startup. The apparatus includes a storage means and a microprocessor, and the microprocessor calculates the fuel injection amount based on the information stored in the temporary storage means and the detected operating condition of the internal combustion engine, and calculates the fuel injection amount. In an electronic fuel injection control device, the electronic fuel injection control device comprises: a fuel injection control means for controlling the main fuel injection in synchronization with the rotation of the internal combustion engine; a power supply voltage monitoring means for monitoring the state of the power supply voltage; rewriting prohibition means for prohibiting rewriting of the contents of the temporary storage means when the voltage monitoring means detects that the voltage has fallen below a predetermined voltage that guarantees the operation of the microprocessor; When the internal combustion engine is started, the injection control means starts fuel injection at startup when the monitored power supply voltage returns from below the predetermined voltage to above the predetermined voltage, and when it becomes below the predetermined voltage. Control is performed by the microprocessor to stop the fuel injection at the time of starting and accumulate and store the fuel injection amount during that time in the temporary storage means, and the accumulated fuel injection amount is stored in the cooling water of the internal combustion engine. An electronic fuel injection control device, characterized in that the electronic fuel injection control device is configured to control the starting fuel injection until a predetermined value determined based on temperature is reached. 2. The electronic fuel injection control device according to claim 1, wherein the predetermined voltage that guarantees the operation of the microprocessor has a predetermined hysteresis width.