JPH0385345A - Transitional fuel compensation - Google Patents

Abstract

PURPOSE:To improve transitional driving property in a condition where reference injection time is compensated by a coefficient of transitional air fuel ratio compensation, by determining the coefficient based on the variation of intake air quantity at the time of transitional phase of an engine. CONSTITUTION:An electronic controller 4 by which a fuel injection valve 3 installed on an intake tube 2 is controlled based on the information from each sensor and so on, calculates the amount of reference injection based on an engine rotation signal (b) by a crank angle sensor 10 and on an intake pressure signal (c) by a pressure sensor 11. At the transitional state such as the engine acceleration, the amount of intake air at the time of fuel injection by one rotation prior to the last is subtracted from the last intake air amount so as to determine the variation of the amount of intake air, which is multiplied by a predetermined coefficient determined according to the warming condition, so as to determine a coefficient of transitional air fuel ratio compensation. The amount of reference injection is compensated by the coefficient of transitional air fuel ratio compensation and so on, so as to determine the amount of fuel injection.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a transient fuel correction method that can be suitably employed in engines such as automobiles equipped with an electronically controlled fuel injection device.

[Prior Art] This type of engine includes, as prior art to the present invention, for example, as shown in Japanese Patent Application Laid-Open No. 62-38840,
Many engines detect the transient state of the engine based on the amount of change in intake pressure, and increase the amount of fuel for acceleration or decrease the amount of fuel for deceleration based on the detection result. With this type of configuration, the amount of fuel injection can be increased or decreased by determining a transient air-fuel ratio correction coefficient based on the detected amount of change in intake pressure, and correcting the basic injection time using the transient air-fuel ratio correction coefficient. I try to let them do it.

[Problems to be Solved by the Invention] However, the intake pressure may not change accurately depending on the transient state of the engine. For example, as shown in Fig. 4, when acceleration is performed from steady operation, the throttle opening T
As A increases, engine speed NE and intake pressure P
Although M increases, the engine rotation NE continues to increase due to the response delay even after the throttle opening degree TA reaches a constant level (point A), and then shifts to a steady state. Therefore, during transient operation from the time when the throttle opening reaches a certain level (point A) to the time when the engine rotation NE shifts to steady operation (point B), as shown in FIGS. 4 and 5, Even though the intake air ff1Q is substantially constant, the intake pressure PM decreases as the torque and the like decrease. Therefore, based on the amount of change in the intake pressure PM, the transient air-fuel ratio correction coefficient FAE
According to the configuration configured to determine W, during the above-mentioned transient operation, the transient air-fuel ratio correction coefficient FAEW is changed to the negative side as the intake pressure PM decreases, so that the intake air amount remains approximately constant. Despite this, the fuel is decelerated and reduced (shaded area). As a result, the air-fuel ratio becomes lean near the end of acceleration, causing breathing and other problems, which deteriorates drivability.

The present invention aims to eliminate such problems.

[Means for Solving the Problems] In order to achieve the above object, the present invention employs the following configuration.

That is, the transient fuel correction method according to the present invention is configured to determine a transient air-fuel ratio correction coefficient in response to transient changes during acceleration and deceleration of the engine, and correct the basic injection time using the transient air-fuel ratio correction coefficient. In the transient fuel correction method, the transient air-fuel ratio correction coefficient is determined based on an amount of change in intake air amount during a transient period of the engine.

[Function] According to such a configuration, the transient air-fuel ratio correction coefficient increases in response to an increase in the intake air amount during a transient period of the engine, and decreases in response to a decrease in the intake air amount during a transient period of the engine. It turns out. As a result, the fuel correction amount during engine transients is not affected by changes in intake pressure, but is directly adjusted according to changes in intake air amount, so it can be adjusted accurately according to transient conditions. It becomes possible to perform air-fuel ratio control during transient periods.

[Example] Hereinafter, an example of the present invention will be described with reference to FIGS. 1 to 3.

The engine schematically shown in FIG. 1 is installed in an automobile and is equipped with an electronically controlled fuel injection device 1. As shown in FIG. This electronically controlled fuel injection device 1 is configured to detect the amount of intake air based on intake pressure, engine rotation, etc., and is configured to detect a fuel injection valve 3 attached to an intake pipe 2 and a fuel injection time of the fuel injection valve 3. It is equipped with an electronic control device 4 for controlling. The amount of fuel supplied from the fuel injection valve 3 to the combustion chamber 5 is adjusted by the electronic control device 4 based on information from various sensors and the like.

The fuel injection valve 3 has a built-in electromagnetic coil, and when a fuel injection signal a is applied to the electromagnetic coil from the electronic control device 4, it injects fuel in an amount corresponding to the application time into the vicinity of the intake boat. It looks like this.

The electronic control device 4 includes a central processing unit 6 and a memory 7.
It consists of a microcomputer unit equipped with a human power interface 8, an output interface 9, etc. The input interface 8 receives at least an engine rotation signal from a crank angle sensor 10, an intake pressure signal C from a pressure sensor 11, a water temperature signal d from a water temperature sensor 12 that detects the temperature of engine cooling water, etc. It is becoming human-powered. The output interface 9 is configured to output a fuel injection signal a to the fuel injection valve 3.

The crank angle sensor 10 is configured to output a signal according to engine rotation, and is built into the distributor 13. The pressure sensor 11 is configured to output a signal according to the intake pressure, and is provided in the surge tank 14. The water temperature sensor 12 includes a built-in thermistor and the like, and outputs a signal corresponding to the engine cooling water temperature.

Further, the electronic control device 4 has a built-in program as schematically shown in FIG. 2, and is set to be executed at each fuel injection timing. First, in step 51, the intake air amount Q is calculated based on the basic injection time TP and the engine rotation NE, and the process proceeds to step 52. The basic injection time TP is determined according to the intake air amount calculated based on the engine rotation signal S, the intake pressure signal C, and the like. Since this basic injection time TP is determined by the engine rotation NE per unit time and the intake air amount Q, as shown in the following equation, the intake air amount Q is calculated by back calculation of this relational expression. be able to.

TP=Q, (g/s)/NE (rpm) Step 52
Now, subtract the intake air amount Q 5l-1 at the time of fuel injection one revolution before from the latest intake air ff1Q, , calculate the amount of change ΔQ in the intake air amount Q during the rainy period, and proceed to stitch 53. . In step 53, a predetermined coefficient a determined depending on the warm-up state, etc. is applied to the amount of change ΔQ in the intake air amount Q.
, the transient air-fuel ratio correction coefficient FAEW is determined, and the process proceeds to steps 5 and 4. In step 54, as shown in the following equation, the basic injection time TP is corrected by adding 1 to the transient air-fuel ratio correction coefficient FAEW and various correction coefficients determined depending on the engine condition, and the invalid injection time N to determine the fuel injection time T. The fuel injection valve 3 is opened for a time corresponding to the determined fuel injection time T, and fuel injection is performed.

T product TPx (1 + FAEW) increases, but after the throttle opening TA reaches a certain level, the engine rotation NE (
Point A) also continues to rise due to the response delay, and then shifts to a steady state. In this case, during transient operation from the time when throttle opening TA reaches a certain level (point A) to the time when engine rotation NE shifts to steady operation (point B), even if the detected intake pressure PM decreases, , the intake air amount Q, are approximately constant, and during this period, the amount of change ΔQ in the intake air amount Q,
becomes 0. As a result, the fuel is not throttled by the transient air-fuel ratio correction coefficient FAEW near the end of acceleration, and the fuel supply amount is adjusted to an amount that matches the intake air amount in this region.

Therefore, with such a configuration, even if the intake pressure decreases near the end of acceleration, the amount of change in the intake air amount is not affected by transient changes in the intake pressure. Since the acceleration increase amount of fuel can be determined appropriately in accordance with the above, it is possible to reliably improve the accuracy of fuel control during transient times. As a result, it is possible to effectively prevent the air-fuel ratio from changing to lean in the region immediately before acceleration ends, which causes breathing problems, and reliably improves drivability from the start of acceleration to immediately after the end of acceleration. can be done.

Note that the present invention is applicable not only to the case where engine rotation is detected using a crank angle sensor but also to the case where engine rotation is detected using an ignition signal.

[Effects of the Invention] According to the present invention configured as described above, when the engine shifts to a transient state, it is possible to appropriately adjust the fuel supply amount according to the amount of change in the intake air amount at that time. I can do it,
Since it is possible to effectively suppress the air-fuel ratio from changing to lean in the region where the engine transitions from a transient state to steady operation, the air-fuel ratio control accuracy can reliably improve drivability during engine transients. It is possible to provide an excellent transient fuel correction method.

[Brief explanation of drawings]

1 to 3 show an embodiment of the present invention, FIG. 1 is a schematic overall configuration diagram, FIG. 2 is a flowchart diagram schematically showing a control procedure, and FIG. 3 is a control mode. It is a timing chart figure. Fig. 4 is a timing chart equivalent to Fig. 3 showing a problem in the conventional example, and Fig. 5 is the same.
It is a figure which shows the malfunction in a conventional example. 1... Electronically controlled fuel injection device 3... Fuel injection valve 4... Electronic control device 10... Crank angle sensor 11... Pressure sensor

Claims (1)

[Claims] In a transient fuel correction method configured to determine a transient air-fuel ratio correction coefficient in response to transient changes during engine acceleration/deceleration, and correct the basic injection time using the transient air-fuel ratio correction coefficient, the transient air-fuel ratio correction A fuel correction method during a transient period, characterized in that a coefficient is determined based on an amount of change in intake air amount during an engine transient period.