JPH02238145A - Fuel injection control device - Google Patents

Abstract

PURPOSE:To prevent a deterioration of the combustion property by stopping the increase of fuel for a specific period after the starting, in a control device in which the air intake pipe pressure and a specific value are compared to detect the high loading condition of the engine, and the fuel is increased responding to the detecting result. CONSTITUTION:While an engine 1 is being operated, first it is decided whether the opening of the throttle valve detected by a throttle sensor 4 is more than a specific value or not in an ECU 5, and when it is YES, an increasing correction in a high load condition is performed. On the other hand, when the decision is NO, it is decided whether a specific time or more passes after the starting or not, and when such a time passes, it is decided whether the air intake pipe pressure detected by an air intake pressure sensor 8 is more than a specific value or not. And when it is more than the specific value, it is decided to be a high load and an increasing correction is performed. In such a way, by prohibiting the high load increasing by the air intake pressure for a specific period after the starting when the throttle valve opening is less than a high load deciding value, an excessive fuel increasing by an error detection is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an electronic fuel injection control device for automobiles, etc., and particularly relates to an improvement in its fuel increase function. <Prior art> In internal combustion engines (hereinafter referred to as engines) such as those used in automobiles, a rich air-fuel mixture is required during high-load operation.
It is necessary to increase the amount of fuel supplied to the engine. For this reason, the electronic fuel injection control system is equipped with means for detecting the high-load operating state of the engine by detecting the intake pipe pressure and comparing it with a predetermined value. When a high load condition is detected, fuel increase correction is performed during the fuel injection control process. As a prior art, for example, there is Japanese Patent Publication No. 62-29622. However, in such an electronic fuel injection control device, especially when it is cold, for a certain period of time from immediately after starting until it warms up, it is possible to operate under high load even though the throttle valve is fully closed (idling state). This was detected and the fuel increase function was activated in some cases. To explain this with Figure 4, the engine speed Ne exceeds the start judgment level at timing A1, and the start mode switches to the post-start operation mode. Immediately after a slow start, engine friction is large due to increased viscosity of lubricating oil, etc., so the solid line Ne does not immediately rise to the specified idling speed, but rises after a certain time delay. There is also a time delay until the pipe pressure (absolute pressure, the same applies hereinafter) PM reaches the predetermined suction negative pressure, and it moves as shown by the solid line PM.If this is after warm-up, it will occur at the start judgment point, that is, timing Al'. Immediately, the dashed line Ne' reaches its peak and the dashed line PM' reaches its peak.However, in cold conditions, timing A1 is passed and timing A is reached.
2, the intake pipe pressure PM continues to be at or above the high load judgment level. Therefore, in the conventional fuel injection control device, the fuel increase function operates during the TO period even though the vehicle is in an idling state.

As a result, the engine becomes overrich immediately after starting, causing problems such as unstable rotation, smoldering plugs, poor fuel efficiency, and poor exhaust gas. (Problems to be Solved by the Invention) In order to solve the above-mentioned problems, the present invention provides a fuel injection control device that can prevent the fuel increase function from activating as a result of erroneously detecting a high load condition immediately after starting the engine. (Means for solving the problem) The above purpose is to detect a high load state of the engine and increase the amount of fuel by comparing the intake pipe pressure with a predetermined value. This is achieved by a fuel injection control device characterized in that the fuel injection control device is provided with a means for stopping the increase in fuel amount for a predetermined period after startup. (Function) The fuel injection control device of the present invention According to the above, since a means for stopping the fuel increase for a predetermined period after startup is provided, a high-load fuel increase will not be performed during idling operation. Fig. 2 is an overall configuration diagram of a fuel injection control device to which the present invention is applied.A throttle valve 3 is provided in the middle of an intake pipe 2 connected to an engine 1. A throttle sensor 4 is connected to the valve 3.
The opening degree of the throttle valve 3 is detected and a throttle valve opening degree signal is sent to the electronic control unit (hereinafter referred to as ECU) 5. The fuel injection valve 6 is provided for each cylinder, and is connected to a fuel pump (not shown) and electrically connected to the ECU 5.
Fuel injection is controlled by a drive signal from the ECU 5.
Immediately downstream of the throttle valve 3, an intake pressure sensor 8 is provided via a pipe 7. The intake pressure sensor 8 detects the absolute pressure inside the intake pipe 2 and sends an intake pressure signal to the ECU 5. A water temperature sensor 9 is provided in the main body of the engine 1. That is, the water temperature sensor 9 is installed in the circumferential wall of the engine cylinder filled with cooling water, detects the cooling water temperature, and sends a temperature signal to the EC.
Send to U5. A crank angle sensor 10 is provided around the crankshaft of the engine 1, and outputs one pulse signal at a specific predetermined crank angle position and sends it to the ECU 5, whereby the engine speed is calculated. FIG. 3 is a block diagram showing the internal configuration of the ECU 5 shown in FIG. 2. Each signal from the intake pressure sensor 8, throttle sensor 4, and water temperature sensor 9 enters the level correction circuit 51 and is sent to the AD
The signal is input to the CPU 53 via the converter 52. The signals from the crank angle sensor 10 are input to the CPtJ 53 via the waveform shaping circuit 54.The CPU 53 to which the ROM 55 and RAM 56 are connected performs arithmetic processing on each input signal, and passes through the drive circuit 57 to the fuel injection valve 6. Send a drive signal to. FIG. 1 shows a flowchart of the fuel increase control process during high load in the first embodiment. Throttle valve opening T in step 1
Determine whether A is greater than or equal to the judgment value. When it is equal to or greater than the judgment value (at high load and 0 load), the process goes to step 4, performs the increase correction at high load, and returns from this processing routine. If TA is less than or equal to the judgment value in step 1, it is determined in step 2 whether a certain period of time has elapsed after startup, and if so, the process proceeds to step 3 and it is determined whether or not the intake pipe pressure PM is greater than or equal to the judgment value. , the load is determined to be high when it is equal to or greater than the judgment value, the load is increased in step 4, and the process returns from this processing routine. If PM is less than the determination value in step 3, the process returns from this processing routine without executing step 4. Further, if it is determined in step 2 that a certain period of time has not elapsed since startup, step 34 is not executed and the process returns from this processing routine. As a result, when the throttle valve opening is less than the high load judgment value and within a certain period of time after starting, PM is prohibited from increasing the amount of fuel under high load, thereby preventing excessive fuel increase due to erroneous detection. To explain this with reference to FIG. 4, in this invention, the high load detection function based on the intake pipe pressure PM is stopped during a certain period T1 after the start determination, so the fuel increase function is erroneously activated between timings A1 and A2. It can be prevented from operating. FIG. 5 shows a flowchart of the fuel increase control process at high load in the second embodiment. This means that Step 6 is inserted between Step 1 and Step 2 in the flowchart in Figure 1, and Step 2 in Figure 1 has been rewritten as Step 2°. In this embodiment, before determining in step 2' whether a certain period of time has elapsed after startup, in step 6, the period T1 used for determination is determined based on the engine temperature at that time.
Calculate. This makes it possible to provide a judgment value T1 that corresponds to the TO period, which varies depending on the temperature, in accordance with the engine characteristics, making it possible to perform accurate control. FIG. 6 shows a flowchart of the fuel increase control process during high load in the third embodiment. That is, in step 5, the engine temperature used for determination is compared with a determination value, and when the engine temperature is less than the determination value, the process proceeds to step 2, in which it is determined whether a certain period of time has elapsed after startup. Also, if the engine temperature is above a certain value in step 5, go to step 3,
High load is determined based on intake pipe pressure. The following flowchart is the same as that of the first embodiment.

FIG. 7 shows a flowchart of the fuel increase control process at high load in the fourth embodiment. This subroutine is executed once each time injection is performed. In this processing routine,
A flag x1 is used to determine whether the intake pipe pressure is in a high load state. When the engine is started, the flag X1 is initialized to O, and this process is repeated.

When the engine is started, as shown in FIG. 4, since PM>judgment value, the process proceeds from step 3 to step 8. Here, it is determined whether the value of flag X1 is 1 or not. Immediately after starting, the flag X1 is O, so the process skips step 4 and no increase correction is performed. This process is repeated at each injection timing, and when the timing A2 in FIG. 4 comes, the result in step 3 is No, and the flag X1 is set to 1. Then, at the time of the next injection, if a high load condition is detected in step 3, step 8 becomes YES, so that an increase correction is performed. As a result, while a high load state is erroneously detected immediately after startup, the increase correction is prohibited; on the other hand, after a predetermined period of time has passed and a state has been reached where a high load state will not be erroneously detected, The amount will be increased each time a high load is detected. As explained in the fourth embodiment, the predetermined period after startup of the present invention is not necessarily limited to the elapsed time, but may be a period until a certain condition is satisfied as in this embodiment. Also,
In this invention, as in the first to third embodiments,
In addition to the method of not determining whether the load is high for a predetermined period after starting, as explained in the fourth embodiment,
For example, this includes a method in which the amount of fuel is not increased even if a high load is detected as long as the intake pipe pressure has never fallen below the high load judgment value. In both Figures 1.5 and 6.7, it is determined in step 1 whether the opening degree TA of the throttle valve is greater than or equal to a predetermined value, and if it is greater than or equal to the predetermined value, an increase correction is made. ing. This is to deal with the case where the engine is raced immediately after starting, and is not necessarily required in the present invention. (Effects of the Invention) Since the present invention is a fuel injection control device configured as described above, it is possible to prevent malfunction of the fuel increase function due to high load detection of intake pipe pressure in the idling state immediately after startup, and therefore This prevents deterioration of drivability due to over-richness immediately after starting, smoldering of the plug, deterioration of fuel efficiency, deterioration of emissions, etc.

[Brief explanation of drawings]

FIG. 1 is a flowchart of the fuel increase control process according to the first embodiment;
Figure 2 is an overall configuration diagram of the fuel injection control device, and Figure 3 is the overall configuration of the fuel injection control device.
4 is an operational explanatory diagram of the fuel increase control process in the operating state immediately after the engine starts, FIG. 5 is a flowchart of the fuel increase control process according to the second embodiment, and FIG. 6 is a flowchart of the fuel increase control process according to the second embodiment. Flowchart of the fuel increase control process according to the embodiment. FIG. 7 is a flowchart of the fuel increase control process according to the fourth embodiment. 1... Engine 2... Intake pipe 3... Throttle valve 4... Throttle sensor 5... Electronic control unit (ECU) 6... Fuel injection valve 8... Intake pressure sensor 9... ...Water temperature sensor 10...Crank angle sensor

Claims (1)

[Claims] In a fuel injection control device equipped with a means for detecting a high engine load condition and increasing the amount of fuel by comparing intake pipe pressure with a predetermined value, the increase in fuel amount is stopped for a predetermined period after startup. 1. A fuel injection control device characterized by comprising means.