JPH0361644A - Correction of fuel injection quantity in warming - Google Patents

Abstract

PURPOSE:To surely improve the drivability after start by increased quantity-correcting the fuel injection quantity by the increased quantity correction coefficient corresponding to the cooling water temperature and then revolution speed when the engine revolution speed at each engine cooling water temperature reduces below an aimed revolution speed, exceeding a prescribed quantity. CONSTITUTION:Each of the air-fuel ratio A/F and the engine revolution speed is not markedly different in case of the use of a standard fuel and the use of the lower grade fuel having the higher evaporation temperature, since the fundamental injection quantity is increase-corrected drastically by one after-start increased quantity correction coefficient FSEA immediately after the engine start. As the after-start increased quantity correction coefficient FSEA speedily reduces to zero, the air-fuel ratio speedily changes to lean side, when the fuel injection quantity is speedily reduced, if the fuel having the high evaporation temperature is used, and the engine revolution speed starts reduction. When the difference between the revolution speed at that time and the aimed revolution speed is relatively large, and exceeds a prescribed limit value, the fundamental injection quantity is corrected by the increased quantity correction coefficient FSE and other after-start increased quantity correction coefficient FSEB, and the injection quantity is increase-corrected.

Description

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

[Prior Art] Generally, in this type of engine, as shown in FIG.
Post-start increase correction coefficient F determined according to engine coolant temperature
SEA, FSEB, etc. are used to increase the fuel injection amount during warm-up to supply a rich mixture to the combustion chamber to deal with combustion instability immediately after startup.1. As the warm-up progresses, the increased amount of correction is gradually attenuated to shift to economical operation after the warm-up is completed.

However, since such control is set to correspond to a specific standard fuel, if another fuel with different volatility etc. is used, the fuel injection amount will not be adjusted appropriately depending on the engine situation. . For example, inferior fuels with higher evaporation points than standard specific fuels have poor vaporization properties, so when such fuels are used, the air-fuel ratio A/F becomes over-lean, as shown in Figure 5. Become. Therefore, increasing the amount after starting does not result in sufficient combustion, which causes the engine speed to drop, leading to engine stall or rough idling. Even with such fuel, when the temperature around the combustion chamber and valves rises sufficiently, the vaporization of the fuel improves, and the engine rotation becomes stable.

In order to deal with this problem, as a prior art of the present invention, for example, as shown in Japanese Patent Laid-Open No. 147036/1982, the specific gravity of the fuel used is determined based on the fuel injection amount when the air-fuel ratio is feedback-controlled. Some systems detect this and correct the fuel injection amount when fuel with different properties is used.

[Problem to be Solved by the Invention] However, the device having such a configuration calculates the fuel injection amount when the air-fuel ratio is feedback-controlled, calculates the specific gravity of the fuel used based on the calculation result, and then calculates the specific gravity of the fuel used. Since the fuel correction coefficient is determined in accordance with the specific gravity, it is necessary to go through a complicated control procedure.

The present invention aims to solve the above-mentioned problems without causing such problems.

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

In other words, the fuel injection amount correction method during warm-up according to the present invention is based on the target engine speed corresponding to each engine cooling water temperature when using a specific fuel, and the actual engine speed at each engine cooling water temperature. If the actual engine speed at each engine coolant temperature exceeds a predetermined amount and falls below the target speed, fuel injection is performed using an increase correction coefficient corresponding to each engine coolant temperature and engine speed. The feature is that the amount is corrected by increasing the amount.

[Operation] When a standard specific fuel is used, the engine speed at each engine cooling water temperature is approximately fixed. Therefore, by comparing the target rotational speed and the actual engine rotational speed at each engine cooling water temperature, the nature of the fuel used can be easily determined. If the actual engine speed exceeds a predetermined amount and is lower than the target speed, the fuel injection amount at that time is increased by the increase correction coefficient, so the air-fuel ratio is adjusted to the rich side, and the engine The rotational speed will rise to around the target rotational speed.

[Example] Hereinafter, an example of the present invention will be described with reference to FIGS. 1 to 4.

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. The electronically controlled fuel injection device 1 includes a fuel injection valve 3 attached to an intake pipe 2 and an electronic control device 4 that controls the operation of the fuel injection valve 3. The amount of fuel supplied to the engine 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 port. It looks like this.

The electronic control device 4 includes a central processing unit 6 and a memory 7.
and a microcomputer unit equipped with an input interface 8, an output interface 9, etc., and the input interface 8 has at least the following:
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. are input. The output interface 9 outputs a fuel injection signal a toward the fuel injection valve 3.

The crank angle sensor 10 is configured to output an electrical signal according to the engine speed, and is built into the distributor 13. The pressure sensor 11 is configured to output an electrical signal according to the intake pressure, and is provided in the surge tank 14 . The water temperature sensor 12 is
It consists of a built-in thermistor, etc., and outputs an electrical signal depending on the engine coolant temperature.

Further, the electronic control device 4 is configured to calculate the intake air amount from the engine rotation signal S, the intake pressure signal C, etc., and determine the basic injection amount for each fuel injection timing according to the calculated intake air amount. It is.

After the engine is started, the basic injection amount is increased by a post-start increase correction coefficient FSEASPSEB determined by the engine cooling water temperature. On the other hand, the initial value of the post-start increase correction coefficient PSEA is determined by the engine cooling water temperature at the time of starting, and after the initial value shifts after starting, it is rapidly attenuated to 0 every time the fuel injection amount is calculated. There is. The other post-start increase correction coefficient FSEB is a transient correction coefficient whose value is smaller than the post-start increase correction coefficient PSEA, and its initial value is determined by the engine cooling water temperature at the time of start, and the initial value shifts after the start. It is gradually attenuated from 0 to 0 at predetermined time intervals.

The electronic control unit 4 also compares the target rotation speed at each engine cooling water temperature when using a standard specific fuel with the actual engine rotation speed at each engine cooling water temperature, and determines the actual engine rotation speed. If the engine rotation speed exceeds a predetermined amount and is lower than the target rotation speed, a program as schematically shown in FIG. 2 is set to be executed.

First, in step 51, one post-start increase correction coefficient P
It is determined whether SEA is 0 or not, and if it is determined that it is not 0, the process proceeds to step 55, and if it is determined that it is 0, the process proceeds to step 52. In step 52, it is determined whether or not the other post-start increase correction coefficient PSEB is 0. If it is determined to be 0, the process proceeds to step 55, and if it is determined not to be 0, the process proceeds to step 53. In step 53, it is determined whether or not the engine cooling water temperature exceeds 50oC. If it is determined that it is, the process proceeds to step 55; if it is determined that it is not, the process proceeds to step 54.

In step 54, an increase correction coefficient PSE is calculated from each engine cooling water temperature and engine rotation speed, and step 56
Proceed to. As shown in Fig. 4, this increase correction coefficient PSE gradually decreases as the engine coolant temperature increases when the engine speed is constant; The value is set so that it becomes smaller as the value increases. In step 55, the increase correction coefficient PSE is set to O, and the process proceeds to step 56.

In step 56, the other post-start increase correction coefficient PSEB
The increase correction coefficient PSE is added to , and these values are reflected in the fuel injection ff1T. Specifically, the above correction coefficient FS
EASPSEB, PSE, and various correction coefficients determined depending on the engine condition are set to 1, and the basic injection mTP is corrected using the invalid injection time N to determine the fuel injection ff1T.
TPX (FSEA +FSEB+PSE) XK
10 N), the fuel injection valve 3 is opened for a time corresponding to the fuel injection amount T, and fuel is supplied to the combustion chamber 5. Note that the fuel injection flT is throttled down when the atmospheric pressure becomes low, and is increased when the atmospheric pressure becomes high.

According to such a configuration, as shown in FIG. 3, immediately after starting the engine, one of the post-start increase correction coefficients PSEA
Since the basic injection amount TP is significantly increased by
The air-fuel ratio A/
F and engine speed are unlikely to differ significantly. Therefore, when the fuel injection amount T is rapidly reduced as the post-start increase correction coefficient FSEA is rapidly attenuated to O, if fuel with a high evaporation point is used, the air-fuel ratio A/P As the engine speed rapidly changes to one side, the engine speed begins to decrease. If the difference between the engine speed and the target speed at that time is relatively large and exceeds a predetermined limit, the basic injection ff1TP is corrected by the increase correction coefficient PSE and the other post-start increase correction coefficient ['SEB. , the fuel injection amount T is corrected to increase. For this reason, the air-fuel ratio of the air-fuel mixture approaches the appropriate value and the engine speed increases, so the increase correction coefficient PSE becomes smaller and the fuel injection amount T gradually decreases as warm-up progresses. It will be narrowed down. When the temperature of the engine coolant exceeds the set value and sufficient warm-up is performed, the vaporization of the fuel improves even if the fuel has a high vaporization point, so there is no need to make any special correction to increase the fuel injection ff1T.

Furthermore, when standard fuel is used, the engine rotation is suitable for each engine cooling water temperature, so no increase correction of the fuel injection ftT is performed using the increase correction coefficient PSE.

Therefore, according to such a configuration, the evaporation point is high;
If another fuel is used that is inferior to standard fuel in terms of vaporization, etc., the fuel injection amount will be significantly increased, so the air-fuel ratio and engine speed during warm-up will need to be adjusted to suit the warm-up condition. The value can be effectively corrected and sufficient warm-up can be performed.

As a result, it is possible to prevent the air-fuel ratio from becoming over-lean during warm-up, resulting in a drop in engine speed and leading to an engine stall, or from causing the engine to idle roughly after warm-up, which reliably improves drivability after starting. can be done.

Note that the increase correction coefficient for correcting the fuel injection amount when a different type of fuel is used can be further subdivided for each engine rotation, and its changing state is not limited to the example shown in the drawings. Of course.

[Effects of the Invention] According to the present invention configured as described above, even if fuels with different properties are used, the engine can be warmed up sufficiently and smoothly according to each fuel used.
It is possible to provide a fuel injection amount correction method during warm-up, which can improve drivability after starting the engine and can effectively prevent the occurrence of engine stalls and the like.

[Brief explanation of drawings]

1 to 4 show one 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. 4 are diagrams showing the characteristics of the increase correction coefficient. FIG. 5 is a diagram corresponding to FIG. 3 showing a conventional example. 1... Electronically controlled fuel injection device 3... Fuel injection valve 4... Electronic control device 10... Crank angle sensor 12... Water temperature sensor

Claims (1)

[Claims] Compare the target rotation speed corresponding to each engine cooling water temperature when using a specific fuel with the actual engine rotation speed at each engine cooling water temperature, and determine the actual engine rotation speed at each engine cooling water temperature. When the engine speed exceeds the fixed value and falls below the target engine speed, the fuel injection amount is increased by an increase correction coefficient corresponding to each engine cooling water temperature and engine speed. Fuel injection amount correction method.