JPH03271539A - Starting control device of engine - Google Patents

Abstract

PURPOSE:To improve restartability after an engine stop by stopping supply of fuel to scavenge residual fuel till a predetermined condition is established, when the engine is forcedly rotated for restarting it after generation of a rotation stop condition of the engine is detected. CONSTITUTION:In an ECU100 during operation of an engine 10, output signals of a water temperature sensor 14, crank angle sensor 12 and a pressure sensor 8 are input to a CPU150. At the time of NO-judging with an engine stop generated by first judging whether or not an engine speed NE is 10rpm or more, supply of fuel thereafter is stopped by setting the valve open time TAU of an injector to zero. When the engine 10 is restarted after the engine stop, the supply of fuel is stopped during the time before the engine 10 is rotated up to 720 deg. by a starter motor 16 during restarting, and the engine 10 is placed in a condition equal to that it is normally stopped by scavenging residual fuel in a cylinder.

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a device for controlling the amount of fuel supplied to an engine during engine startup, and particularly to a control device that improves starting performance when restarting the engine after it stalls. [Prior Art] As a technique for controlling the amount of fuel supplied during engine startup, a technique described in Japanese Patent Application Laid-Open No. 126239/1983 is known. This technology makes it possible to obtain good starting performance by reducing the amount of fuel during starting as the cranking speed increases. [Problems to be Solved by the Invention] However, this technology does not take into account the case where the engine is restarted after it has stalled. Here, engine stalling means that the engine ignition switch is on and the electrical equipment that controls the engine, such as the l'EcU (engine control unit), injector (electromagnetic fuel injection valve), etc., is operating normally. This refers to a situation where the engine stops rotating while the engine is running, for example due to a clutch operation error. When the engine rotation is stopped by turning off the engine ignition switch, that is, when the engine rotation is normally stopped, after the ECU or injector stops operating, the engine rotates with inertia for a while, and then completely stops. Stop at. Therefore, the engine continues to rotate for a while after the fuel supply is stopped, and during this time the air-fuel mixture in the cylinder is scavenged. Therefore, when the engine stops normally, no fuel remains in the cylinder. A conventional starting control device plans to start the engine in this state. The technique disclosed in Japanese Unexamined Patent Publication No. 62-126239 also plans to start the engine in this state. On the other hand, if the engine rotation stops due to engine stalling, even if the fuel is supplied in synchronization with the engine rotation, the fuel will continue to be supplied until the engine completely stops. No scavenging phenomenon occurs. Therefore, when the engine is stopped due to engine stalling, fuel remains in the cylinder. Conventional twin engine start control devices restart the engine using the same control as when the engine is stopped normally, even when the engine is restarted after the engine has stalled. Therefore, when restarting the engine after stalling, the air-fuel ratio of the air-fuel mixture becomes overrich by the amount of fuel remaining in the cylinder, making it difficult to start the engine. Therefore, the present invention aims to develop a starting control device that can improve restartability after an engine stall. [Means for Solving the Problems] The above-mentioned problems include a means for monitoring the occurrence of a stopped state of rotation of the engine while the ignition switch of the engine is in an on state, and a means for monitoring the occurrence of a state of stopped rotation of the engine by the monitoring means. When the engine is forcibly rotated for restarting after the detection, the fuel supply control means stops the fuel supply for scavenging until a predetermined condition is satisfied, and then starts the fuel supply. This problem is solved by a characteristic engine starting control device. [Operation] According to the starting control device having the above-mentioned means, the monitoring means monitors whether the rotation of the engine has stopped while the ignition switch is on, that is, whether an engine stall has occurred. When the engine is forcibly rotated to restart after the occurrence of an engine stall is detected, fuel is not initially supplied. Therefore, the fuel remaining in the cylinder is scavenged. Then, the fuel supply is resumed when a predetermined condition (here, the predetermined condition is a condition that is satisfied when the scavenging is completed, and can be determined in advance for each engine) is satisfied. Therefore, the air-fuel ratio of the air-fuel mixture does not become overrich during engine starting, and the engine can be started under the same conditions as when starting a normally stopped engine. [Effects of the Invention] As described above, in the case of the present invention, when restarting the engine after it stalls, since air is first scavenged and then fuel is supplied, the warm air mixture becomes overrich during startup, impairing startability. Never. Furthermore, since scavenging is normally carried out in an extremely short period of time, the time it takes for the Yu7jin to fully explode (in a state where it continues to rotate spontaneously) after the restart operation does not actually take a long time. As described above, according to the present invention, restartability after an engine stall is improved. When the engine stalls, it is usually required to restart the engine quickly, and the present invention can be said to be an extremely practical invention that can meet this urgent need. [Example] Next, an example embodying the present invention will be described with reference to the drawings. FIG. 3 shows an outline of an engine system implementing the starting control device of the present invention. In the figure, 10 is the engine body, 4
2 is an intake pipe, 2 is a throttle valve, 8 is a pressure sensor that detects the pressure inside the intake pipe 2, and 2 is a crank angle that outputs a pulse every time the crank of the engine 10 rotates by a predetermined angle through the rotation of the camshaft. 14 is a temperature sensor that detects the temperature of the cooling water of the engine 10; 6 is an injector that supplies fuel to the engine 10; 16 is a starter motor that forcibly rotates the engine 10 for starting; 18 is an ignition switch; 20 is a battery, 22 is a starter switch, 100 is an engine control unit (E
CU). This engine system has a control system roughly shown in FIG. ECUloo has a multiplexer 110, and the pressure sensor 8 and water temperature sensor 14 are connected to the multiplexer 110, and a signal from either one is sent to an A/D converter 112 where it is A/D converted and digitized information. can be input to the CPU (central processing unit) 150. Further, different signals can be input to the CPUI 50 depending on whether the starter motor 16 is being rotated or not. Furthermore, the pulse wave from the crank angle sensor 12 can be input to the CPU 150 after being waveform-shaped by a waveform shaping circuit 114 . Based on the program stored in the ROM 120, the CPU 150 inputs signals from each signal source in a predetermined procedure and timing, processes them based on the program, and sends a drive pulse signal to the injector drive circuit 116 according to the processing result. Output. The injector drive circuit 116 turns on and off the current flowing through the injector 6 based on a pulse signal sent from the CPU 150. Note that 122 is a RAM, and the CPU1
50 processes. This ECUloo is configured to operate by being supplied with drive current from the battery 20 while the ignition switch 18 is turned on. FIG. 1 shows a control procedure when the CPU 150 performs calculations and processes according to the program stored in the ROM 120. This control procedure is performed using the ignition switch I8.
While on, it is executed repeatedly in synchronization with the engine rotation. In other words, the number of pulses from the crank angle sensor 12 is
It is executed immediately before every time the engine 10 reaches the number of pulses corresponding to the fuel supply timing. In step 400, data regarding the cooling water temperature (THW) is transferred from the signal of the water temperature sensor 14 to the crank angle sensor 12.
Engine rotation speed (NE) from the time interval of pulse waves from
Data regarding the intake pressure (P
M) is input to the CPU 150. In step 401, the engine speed NE at that time is 10 per minute.
Determine whether or not the rotation is greater than or equal to the rotation. If the engine is rotating normally, the engine rotation speed is 10 rpm or more, and is also 400 rpm or more in step 402. At this time, the basic amount of fuel TP is determined from the intake pressure PM and the engine speed NE (step 403). Furthermore, a correction coefficient KTHW corresponding to the temperature is determined from the cooling water temperature (THW) (step 404), the basic injection amount is corrected based on the correction coefficient, and this is set as the injector valve opening time TAU. In this case, since the determination in step 411 is No, the process of FIG. 1 at that injection timing is ended. After this process is completed, a pulse wave is sent to the injector drive circuit 116 for the time (TAU) calculated in step 405 in synchronization with the fuel injection timing, and the injector 6 is opened for the TAU time. As a result, an appropriate amount of fuel is supplied during normal engine rotation. If the engine stalls in this state and the engine speed drops, the result in step 401 in the process shown in FIG. 1 is NO.
The injector valve opening time TAU is set to zero (step 414). After this, the fuel supply is stopped. At this point, steps 407, 408, and 4 are performed as described later until the engine speed is below 400 rpm and reaches 10 rpm.
09 is being executed, and fuel continues to be supplied until the final speed reaches 10 rpm. and the engine speed is 1
The angle at which the engine rotates after it drops below Orpm until it finally stops is small, and it is not expected that air will be scavenged during that time. Immediately before the engine stalls and the engine speed drops to 1Orpm, when the process proceeds from step 409 to step 411, the result is YES in step 411, and the result in step 412 is No, so the counter CENGST is set in step 413.
is set to 4. Then, after the engine has decreased to 10 rpm or less, step 4
13 is not executed, so CENGST remains at 4 and stalls. Next, FIG. 2 shows a process for changing the counter CENGST, which is executed every time a pulse wave is generated from the crank angle sensor 12. Step 500 is a process of reading the output of the crank angle sensor, and step 501
Then, the input pulse number is 18 if the engine crank angle is 18.
It is determined whether the number of pulses corresponds to the number of pulses when rotated by 0°. And step 5 while not rotating 180°
02.503 is skipped and the process ends. 180°
When it rotates, 1 is subtracted from CENGST in step 503 and this is newly set as CENGST. Note that step 5
When CENGST is zero in step 02, step 503 is skipped, so CENGST never becomes negative. As mentioned above, when the engine stalls and the engine speed falls below 15 Orpm, CENGST is set to 4. After the engine speed drops below 10 rpm, the crank angle increases to 180 rpm before it completely stops.
Since the engine does not rotate more than 1°, CENGST is set to 4 when the engine stalls and comes to a complete stop. As is clear from the process shown in Figure 2, when the engine is restarted after stalling, CENGS
T becomes 3, becomes 2 when rotated by 360 degrees, becomes 1 when rotated by 540 degrees, and becomes zero when rotated by 720 degrees. Now, when the engine is restarted after stalling, the engine speed will be less than 400 rpm due to the capacity of the starter motor, and the answer at step 402 in FIG. 1 will be No. As mentioned above, since CENGST is 1 or more until the crank angle reaches 7200 revolutions after restarting, step 410 is executed during that time, and the injector opening time TAtJ
is set to cello. That is, the supply of fuel is stopped until the engine is rotated 720 degrees by the starter motor during restart. During this time, the fuel remaining in the cylinder when the engine stalls is scavenged, and the engine stops normally.

[The state will be the same as when it was 7. Note that while the starter motor is running, step 413 is skipped based on the determination in step 412, so CEN
GST is never reinitialized to 4. When the rotation is performed by 720° in this state, the answer in step 406 becomes YES, and steps 407 and subsequent steps are executed. In step 407, the basic fuel amount T during engine starting is
Find PST. Then, in step 408, a correction coefficient KNE is calculated based on the engine speed NE. Then, in step 409, the basic fuel amount TPST is corrected and set as the injector opening time TAU. As a result, a normal amount of starting fuel is supplied from the time the engine rotates over 720 degrees for restart. In this way, when the engine is restarted after stalling, the starter motor rotates the engine for the first 720 degrees without supplying fuel to scavenge air, and then fuel is supplied at the time of startup based on step 409. This prevents the air-fuel ratio from becoming overrich and deteriorating the restartability when restarting the engine after the engine stalls. Note that when the engine is normally stopped, CENGST is zero because the execution of the process shown in FIG. 1 is interrupted when the engine rotational speed NE is 400 rotations or more. Therefore, when restarting after that, the judgment in step 406 is Y.
ES, and will not be rotated 720 degrees for scavenging. FIG. 5 illustrates the result of the above action, (I)
shows the case where the engine is restarted after being stopped normally. (a) of FIG. 1(I) shows fluctuations in engine speed, and at timing 1, the ignition switch is turned off. After that, the rotation speed gradually decreases due to inertia, and it completely stops at timing 2. (b) shows the air-fuel ratio at that time, and it is a proper air-fuel ratio when the engine is rotating normally, but after [timing], the air-fuel ratio becomes lean because fuel is not supplied and scavenging occurs. Timing 3 indicates the on-timing of the ignition and starter switches, and in this case, as described above, the fuel supply starts at the same time as each switch is turned on by the processing of steps 406, 407, 408 and 409 in FIG. (indicates the start timing of fuel supply), the air-fuel ratio becomes richer. When the engine reaches a complete explosion (a state in which it can continue to rotate without the help of the starter motor), the air-fuel ratio returns to the proper range. FIG. 1 (II) shows a case where a restart after an engine stall is executed using a conventional starting control method. In this case, the engine stalls at 1' and fuel is supplied until the engine completely stops at 2° (fuel supply is stopped below 10 rpm, but the engine speed is 1 Orpm). This is just before timing 2', and after that, the air is scavenged and the air-fuel ratio does not become lean.Then, when restarting, the same starting fuel as usual is supplied, so the mixture becomes too rich and the engine runs out. A complete explosion does not occur easily.And even if a complete explosion starts, it takes a considerable amount of time to reach the timing of a complete explosion, and the restartability of the engine is poor.In contrast, Fig. 1 (III) shows the present invention. In this case, when the ignition switch and starter switch are turned on at timing 3, air is scavenged during the first two revolutions, and then fuel starts to be supplied at timing 4, so the mixture will not become overrich. , the engine will come to complete explosion smoothly after scavenging. Even with the control method of the present invention, when the engine is restarted after being stopped normally, the process shown in FIG. 1 (I) will not occur. As explained above. In the above embodiment, the counter CENGST is stored in the RAM 122.
An example of how to store the data is shown below. This is effective when turning on the starter switch without turning off the ignition key after the engine stalls. However, once the ignition switch is turned off, CENGST is also initialized to zero and the desired operation cannot be obtained. Therefore, in order to deal with this problem, in the configuration shown in Figure 4, RAMI
A backup battery may be added for 22. In this way, even if the ignition switch is turned off, the contents of CENGST will not be cleared by cello, and the above problem will not occur. Further, in this embodiment, an example is shown in which the rotation angle of the crank is used as a condition for stopping the fuel supply when restarting the engine after the engine stalls. However, the present invention is not limited to this, and the scavenging completion condition may be determined using, for example, the rotation time of the starter motor or the detected value from the air-fuel ratio detection means. Further, it goes without saying that the amount of fuel to be supplied may be calculated not only by the DJ method but also by the L-J method.

[Brief explanation of drawings]

Fig. 1 shows the processing procedure executed by the device of the present invention, Fig. 2 shows the procedure for changing the counter value to stop the supply of fuel until scavenging is completed, and Fig. 3 shows the embodiment of the present invention. FIG. 4 is a block diagram showing the engine control unit and its peripheral equipment, and FIG. 5 is a diagram showing the operation results. 6・Pine injector 16゛”・Starter motor 18゛Ignition switch 22° Starter switch 100-Engine control unit step 401
Processing--Processing step 413 for monitoring the occurrence of engine stalling
．． 501.503.406 Processing for determining scavenging completion conditions Processing for Step 410 Processing for stopping fuel supply Processing for Step 409 Processing for supplying fuel at startup

Claims (1)

[Scope of Claims] Means for monitoring the occurrence of a stopped rotation state of the engine while an ignition switch of the engine is in an on state, and a means for monitoring the occurrence of a stopped state of rotation of the engine after the occurrence of a stopped state of rotation of the engine is detected by the monitoring means. When the engine is forcibly rotated for restarting, the fuel supply control means stops the supply of fuel to perform scavenging until a predetermined condition is satisfied, and then starts supplying the fuel. Control device.