JPS6321816B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention detects the starting time of an internal combustion engine, corrects the increase or decrease so that the amount of fuel supplied at the time of starting becomes an optimal value, rewrites and stores the correction amount, and performs optimal control of the amount of fuel supplied at the time of starting. Regarding an injection device. As is well known, the amount of fuel injected when starting an internal combustion engine is determined by the amount of fuel injected from a main injector and a cold start injector.
However, due to variations in the fuel injection system, engine, etc., there are problems with poor startability due to insufficient fuel supply and plug fogging due to oversupply. The present invention has been made in consideration of the above problems, and detects the starting time, performs an increase/decrease correction calculation so that the amount of fuel supplied at the time of starting becomes an optimal value according to the starting time, and stores the correction amount. It is an object of the present invention to provide an electronically controlled fuel injection device that can further improve startability from the next time onwards by rewriting and storing the information in the section. For this purpose, in the present invention, as shown in FIG. 7, the calculation means calculates the fuel amount according to the operating state detected by the operating state detection means, and The starting correction value in the memory is updated, the correction means corrects the amount of fuel using the updated starting correction value, and the injection means injects the fuel. As a method for this purpose, according to experiments conducted by the inventors, the following relationship exists between the time t ₁ and t ₂ from initial explosion to complete explosion at startup and the air-fuel ratio at startup, as shown in Figure 1. I found out something. That is, the fuel injected when starting the engine adheres to the previously dry inner wall of the intake pipe, intake valve, etc., then vaporizes, is sucked into the engine, and is burned. Therefore, if there is insufficient fuel at startup and the air-fuel ratio is low, this fuel will be left to wet the walls of the intake pipe, delaying the formation of an air-fuel mixture, resulting in a delay in the initial explosion of the air-fuel mixture (time to initial explosion). After _the first explosion, the fuel is sucked into the engine, so the rotation increases smoothly and leads to a complete explosion (the time t ₁ to t ₂ from the first explosion to the complete explosion is short). on the other hand,
If there is too much fuel and the air-fuel ratio is rich at the time of startup, sufficient fuel will be sucked into the engine even if there is fuel adhesion, resulting in a faster initial explosion, but the engine will produce less torque due to the rich mixture. The engine speed rises slowly, and the engine reaches full combustion (approximately 600 rpm) at which it can continue to rotate without the starter being activated. The table below shows the above relationship.

[Table] By utilizing this phenomenon and comparing the starting times at different air-fuel ratios under approximately equivalent starting conditions (for example, conditions determined by the temperature of buckwheat water, etc.), it is possible to set the air-fuel ratio to obtain even better starting performance. For this purpose, the time t ₁ , t ₂ from initial explosion to complete explosion at startup, the water temperature, and the fuel correction amount at startup are measured, and the times t ₁ , t ₂ and starting time corresponding to the previous startup corresponding to this water temperature are measured. Compare with the time fuel correction amount data,
If the above conditions apply, the starting fuel correction amount may be automatically corrected. This can prevent deterioration during startup due to aging or deterioration of the engine or sensors (intake air amount sensor, water temperature sensor, etc.). Furthermore, deterioration in startability due to variations in engines and sensors during mass production can be prevented. The present invention will be explained below by way of an example. Figure 2 is an overall configuration diagram, and 1 is a known 4-cycle spark ignition engine that is installed in a car.
It is inhaled through the throttle valve 4. Further, fuel is supplied from a fuel system (not shown) via electromagnetic fuel injection valves 5 provided correspondingly to each cylinder. The exhaust gas after combustion is released into the atmosphere through an exhaust manifold 6 and an exhaust pipe 7. A potentiometer-type intake air amount sensor 8 is installed in the intake pipe 3 to detect the amount of intake air taken into the engine 1 and output an analog voltage according to the amount of intake air. Furthermore, a thermistor-type water temperature sensor 9 is installed in the engine 1 to detect the coolant temperature and output an analog voltage (analog detection signal) according to the coolant temperature. Further, the intake air temperature sensor 11 is installed downstream of the air cleaner 2.
The rotational speed (number) sensor 10 detects the rotational speed of the crankshaft of the engine 1 and outputs a pulse signal with a frequency corresponding to the rotational speed. This rotation speed (number)
For example, an ignition coil of an ignition device may be used as the sensor 10, and an ignition pulse signal from a primary terminal of the ignition coil may be used as a rotational speed signal. The control circuit 20 is a circuit that calculates the fuel injection amount based on the detection signals of the sensors 8 to 11, and adjusts the fuel injection amount by controlling the opening time of the electromagnetic valve 5. Next, the control circuit 20 will be explained with reference to FIG. 100 is a microprocessor (CPU) that calculates the fuel injection amount. Reference numeral 101 denotes a rotation number counter that counts the engine rotation number based on a signal from the rotation speed (number) sensor 10. Further, this rotation number counter 101 sends an interrupt command signal to the interrupt control section 102 in synchronization with the engine rotation. When interrupt control section 102 receives this signal, it outputs an interrupt signal to microprocessor 100 via common bus 150. 1
03 is a digital input boat, and a starter switch 11 turns on and off the operation of a starter (not shown).
A digital signal such as a starter signal from the microprocessor 100 is transmitted to the microprocessor 100. 103 is a digital input port for inputting engine information, and 104 is an analog input port consisting of an analog multiplexer and an AD converter, which converts each signal from the intake air amount sensor 8, cooling water temperature sensor 9, etc. from AD to AD. It has a function of sequentially reading data into the microprocessor 100. Each of these units 101, 102, 103,
The output information of 104 is transmitted to microprocessor 100 through common bus 150. A power supply circuit 105 supplies power to a RAM 107, which will be described later. 12 is a battery and 13 is a key switch, but the power supply circuit 105 is directly connected to the battery 12 without passing through the key switch 13. Therefore, power is always applied to the RAM 107, which will be described later, regardless of the key switch 13. Power supply circuit 106
is connected to the battery through a key switch 13. The power supply circuit 106 is a RAM 10 which will be described later.
Supply power to parts other than 7. 107 is temporarily used during program operation. It is a temporary memory unit (RAM), but as mentioned above, the key switch 13
Power is always applied regardless of the key switch 13.
The memory contents are not lost even if the engine is turned off and engine operation is stopped, making it a non-volatile memory. The correction amount _K2 , which will be described later, is based on this RAM 107.
is stored in A read-only memory (ROM) 108 stores programs, various constants, and the like. 109 is a fuel injection time control counter including a register, which is composed of a down counter, and converts the digital signal representing the opening time of the electromagnetic fuel injection valve 5 calculated by the microprocessor (CPU) 100, that is, the fuel injection amount into the actual value. It is converted into a pulse signal with a pulse time width that gives the opening time of the electromagnetic fuel injection valve 5.
110 is a power amplifying section that drives the electromagnetic fuel injection valve 5 according to the previous pulse signal. A timer 111 measures the elapsed time and transmits it to the CPU 100.
The rotational speed counter 101 measures the engine rotational speed once per engine rotation based on the output of the rotational speed sensor 10, and when the measurement is finished, the interrupt control unit 102
provides an interrupt command signal to the The interrupt control unit 102 generates an interrupt signal from the signal, and causes the microprocessor 100 to execute an interrupt processing routine for calculating the fuel injection amount. Next, FIG. 4 shows a schematic flowchart of the microprocessor 100, and based on this flowchart, the functions of the microprocessor 100 and the operation of the entire structure will be explained. Key switch 13 and star switch 11 are ON
When the engine is started, the first step is step 1.
At the start of 000, the arithmetic processing of the main routine is started, initialization processing is executed at step 1001, and digital values corresponding to the cooling water temperature, etc. from the analog input port 104 are read at step 1002. In step 1003, a correction amount _K1 , which will be described later, is calculated from the result, and the result is stored in RAM1.
Store in 07. In step 1004, the starting time at starting is measured and the fuel correction amount _K2 at starting is corrected based on the measurement result and stored in the RAM 107. Normally, the main routine processes 1002 to 1004 are repeatedly executed according to the control program. When the interrupt signal for calculating the fuel injection amount is input from the interrupt control section 102, the microprocessor 100 immediately interrupts the main routine even if it is processing the main routine and moves to the interrupt processing routine at step 1010. In step 1011, a signal representing the engine speed N from the rotation speed counter 101 is taken in. Next, in step 1012, a signal representing the intake air amount (intake air amount) Q is taken in from the analog input port 104. Next, in step 1013, a signal representing the engine speed N is taken in from the analog input port 104. The number N and the intake air amount Q are stored in the RAM 107 for later use in calculating ignition timing and other purposes. Next, in step 1014, the basic fuel injection amount (that is, the injection time width t of the electromagnetic fuel injection valve 5) determined from the engine speed N and the intake air amount Q is calculated. The calculation formula is t=F×Q/N (F: constant). Next, in step 1015, various correction amounts for fuel injection determined in the main routine are
It reads out from the RAM 107 and performs correction calculation of the injection amount (injection time width) that determines the air-fuel ratio. The calculation formula for the injection time width T is T=t×K ₁ ×K ₂ . Next, in step 1016, the corrected and calculated fuel injection amount data is set in the counter 109. Next, the process advances to step 1017 and returns to the main routine. When returning to the main routine, the process returns to the processing step at which it was interrupted due to interrupt processing. The general functions of the microprocessor 100 are as described above. A flowchart of step 1004 is shown in FIG. In step 201, the times t ₁ and t ₂ (see Fig. 1) from the initial explosion to the complete explosion are measured. Here, the engine rotational speeds N ₁ and N ₂ are N ₁ = 200 rpm, N ₂ =
Approximately 600 rpm is appropriate. Next step 202
Then, the past data t ₁ , t ₂ and the starting fuel correction amount K ₂ and the code I corresponding to this water temperature condition are read out. At that time, each previous data is (t ₁ ) _o-1 , (t ₂ ) _o-1 , (K ₂ )
Let it be _o-1 . Further, I is a numerical value of (+1) or (-1), indicating whether K ₂ of the previous applicable condition was increased or decreased. The time from the starter ON to the first explosion determined last time in step 203 (t ₁ ) _o-1
and the time (t ₁ )n found this time. If this time is longer this time, in step 204, the previous time ( _t2 - _t1 ) _o-1 and the current time ( _t2 - _t1 )n from the first detonation to the complete detonation are compared. If this time is shorter this time, it is further checked in step 205 based on stored data I whether or not the fuel correction amount was decreased last time. If it has been decreased (I is negative), it can be seen that the air-fuel ratio of the supplied air-fuel mixture has become leaner at the time of startup because the correction amount was decreased last time. In this case, in step 206, the correction amount is corrected to increase. Also, steps 203, 207, 208, 20
In step 9, the opposite case to that described above is checked and corrected. In other cases, the sign of I is changed in step 210, and steps 206 and 20 are changed in step 211.
The correction amount is 1/2 of the correction amount in the case of 9. This is to increase or decrease the correction amount K ₂ and to know whether the current correction amount is appropriate. Then step 21
In step 2, (K ₂ )n, (t ₁ )n, (t ₂ )n, and I are stored in the RAM for the corresponding water temperature condition. This allows RAM
Each data within can be rewritten over time and can be changed to a correction amount according to the engine condition. Here, in this example, the RAM is
It has built-in tables for K ₂ , t ₁ , t ₂ , and I. In addition, in the above embodiment, a case has been described in which fuel correction is performed at the time of startup of the main injector in a system equipped with a main injector (fuel injection valve 5) and a cold start injector (not shown). The present invention can be similarly applied to a system having only a main injector and no injector. In addition, in the above embodiment, only the cooling water temperature is shown as an engine parameter regarding fuel correction at startup, but
It may also be constructed using a multi-dimensional map that includes other engine parameters such as the temperature of intake air into the engine, or a plurality of maps. As described above, in the present invention, the electronically controlled fuel injection device is configured to learn the starting state of the engine, calculate the optimal amount of fuel to be supplied at the time of starting, and rewrite and store it in the nonvolatile memory each time. It is possible to prevent deterioration of startability due to aging and deterioration of the engine and sensors, and also to prevent deterioration of startability due to variations in engines and sensors during mass production.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram for explaining the features of the present invention, Fig. 2 is an overall configuration diagram showing one embodiment of the invention, Fig. 3 is a block diagram showing details of the control circuit,
4 and 5 are flowcharts for explaining the operation of the present invention, FIG. 6 is a diagram showing a table map with built-in RAM, and FIG. 7 is a block diagram showing the general configuration of the present invention. DESCRIPTION OF SYMBOLS 1... Engine, 5... Fuel injection valve, 9... Water temperature sensor, 20... Control circuit.

Claims (1)

[Scope of Claims] 1. Operating state detection means for detecting the operating state of the internal combustion engine; Calculating means for calculating the amount of fuel to be supplied to the internal combustion engine according to the detected value of the operating state detected by the detection means; Starting time detection means for detecting the starting time of the internal combustion engine; and updating means for updating a starting correction value stored in advance in a memory in accordance with a detected value of the starting time detected by the starting time detection means. and a correction means for correcting the calculated value of the fuel amount calculated by the calculation means at the time of starting the internal combustion engine using the starting correction value updated and stored in the memory, and the correction means makes correction by the correction means. An electronically controlled fuel injection device comprising an injection means for injecting the amount of fuel at the time of starting an internal combustion engine.