JPH0427727A - Fuel injection control method in starting engine - Google Patents

Abstract

PURPOSE:To shorten a time from the beginning of cracking in starting an engine at high temperature for re-starting, etc., to the substantial start of the engine by providing such constitution as to prohibit the atmospheric pressure compensation of a fundamental injection amount in starting the engine, when engine cooling water temperature exceeds a set value. CONSTITUTION:When an engine cooling water temperature detected by a water temperature sensor 12 is below a set value, the atmospheric pressure is detected. further and the amount of fundamental injection in starting the engine is compensated by the atmospheric pressure based on the result of the detection. This means that the amount of final injection to be supplied to a combustion chamber 4 becomes practically determined. When the preset combustion injection time comes, a fuel injection valve 2 is opened to carry out fuel injection only for a time corresponding to the amount of the final injection. In this case, the time corresponding to several times of an ignition signal is required from the beginning of cracking to the start of actual feel injection. On the other hand, when the engine cooling water temperature exceeds the set value, the final injection amount is determined according to the amount of the fundamental injection in starting the engine and the unavailable amount of injection.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for controlling fuel injection during engine starting, which is mainly applicable to automobiles.

[Prior Art 1] Generally, in an engine of an automobile or the like equipped with an electronically controlled fuel injection device, the basic injection amount at startup is determined in accordance with the engine cooling water temperature.

Specifically, when the engine cooling water temperature at engine startup is low, the basic injection amount at startup is increased, and when the engine cooling water temperature is high, the basic injection amount at startup is decreased.

In addition, in order to prevent the air-fuel ratio from becoming over-rich due to a decrease in intake air density in areas of high altitude, etc., as a prior art of the present invention, for example, as shown in Japanese Patent Application Laid-Open No. 62-51733, Second, atmospheric pressure is detected when the engine is started, and the basic injection amount at startup is corrected to the atmospheric pressure based on the detection result. That is, when the detected atmospheric pressure is low, the fuel injection amount is decreased accordingly, and when the detected atmospheric pressure is high, the fuel injection amount is corrected to increase.

[Problems to be Solved by the Invention] However, with such a configuration, atmospheric pressure is detected after the ignition switch is operated to the start position, and the basic injection amount at startup is corrected to the atmospheric pressure based on the detection result. Then, the final fuel injection amount is determined. Therefore, a certain waiting time is required between the start of cranking and the actual start of fuel injection, which lengthens the time it takes for the engine to start. Moreover, the above-mentioned atmospheric pressure correction is performed regardless of whether the engine cooling water temperature is high or low, so the difference between the start of cranking and the actual fuel injection is the same when the engine is cold and when restarting at a high temperature. This takes a long time, which is one of the causes of worsening restartability at high temperatures.

However, when the engine cooling water temperature is high, the absolute amount of fuel injection is small, so atmospheric pressure correction at the time of engine startup is not necessarily required.

The present invention focuses on such points and aims to solve the above-mentioned problems.

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

That is, in the fuel injection control method at the time of engine starting according to the present invention, if the engine cooling water temperature at the time of engine starting is lower than the set value, the atmospheric pressure is detected when the ignition switch is operated to the start position, and ,
Based on the detected value, the basic injection amount at startup is corrected to atmospheric pressure when the engine is started, and if the engine cooling water temperature exceeds the set value, atmospheric pressure correction of the basic injection amount at startup is prohibited. It is characterized by the following.

"Operation" According to this configuration, if the engine cooling water temperature is below the set value, the basic injection amount at startup is corrected to the atmospheric pressure, so fuel injection does not actually start from the start of cranking. Although it takes some time for the engine to cool down, it is possible to supply the engine with a mixture suitable for the cold engine conditions.

On the other hand, if the engine cooling water temperature exceeds the set value, the atmospheric pressure correction of the basic injection amount at startup is not performed, and fuel injection is performed immediately upon the start of cranking.

[Example code] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

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 includes a fuel injection valve 2 and an electronic control device 3, and controls the amount of fuel supplied from the fuel injection valve 2 to the combustion chamber 4 based on information from various sensors, etc. This is adjusted by the electronic control device 3.

The fuel injection valve 2 is attached to the intake pipe 5, and has a built-in electromagnetic coil and the like. When a fuel injection signal a is applied to the electromagnetic coil from the electronic control unit 3, an amount of fuel corresponding to the application time is injected into the vicinity of the intake boat.

After the engine is started, the electronic control unit 3 calculates the intake air amount based on the engine speed and intake pressure, and determines the basic injection amount according to the intake air amount. It plays the role of determining the basic injection amount at startup in accordance with the water temperature, and is composed of a microcomputer unit equipped with a central processing unit 6, a memory 7, a human power interface 8, and an output interface 9. There is. The input interface 8 receives at least an engine rotation signal from a crank angle sensor 10, an intake pressure signal C and an atmospheric pressure signal d from a pressure sensor 11, and
A water temperature signal e from a water temperature sensor 12 and a start signal f from an ignition switch 13 are respectively input. Further, from the output interface 9, a fuel injection signal a to the fuel injection valve 3 and a switching valve 1 are sent.
Control signals g to 4 are outputted respectively.

The crank angle sensor 10 is built into the distributor 15 and is adapted to generate an engine rotation signal in response to the engine rotation speed. The pressure sensor 11 is connected to the surge tank 16 via the switching valve 14, and outputs an intake pressure signal C and an atmospheric pressure signal d in proportion to the intake pressure and atmospheric pressure. Switching valve 1
4 is a vacuum switching type three-way valve configured to be selectively connected to the outside air side and the intake side; the first input port 14a communicates with the inside of the surge tank 16; The port 14b is opened to the outside air through a filter (not shown), and the output port 14c is communicated with the inside of the pressure sensor 11. If the electrical input terminal is not energized, the first terminal on the intake side
The input port 14a and the output port 14c are in communication with each other, and when the electric input terminal is energized, the second input port 14b on the outside air side and the output port 14c are in communication with each other. Note that this switching valve 14 is normally connected to the intake side, and is connected to the outside air side when the engine is started or decelerated. Water temperature sensor 12
, for example, has a built-in thermistor or the like, and outputs a water temperature signal e in accordance with the engine cooling water temperature.

The ignition switch 13 is used to control starting and stopping of the engine, and when it is operated to the start position, it outputs a start signal f indicating that the engine is to be started.

Further, the electronic control device 3 has a built-in program as schematically shown in FIG. First, step 51
Then, it is determined whether the ignition switch [G13 is operated to the start position or not. If it is determined that the ignition switch [G13 is operated to the start position, the process proceeds to step 52. In step 52, the starting basic injection amount TSTA is determined based on the engine cooling water ff1THW, and the process proceeds to step 53. The basic injection amount at startup TST^ is the engine cooling water temperature T at the time of engine startup.
The higher the HW, the smaller the amount is set. In step 53, it is determined whether or not the engine cooling water temperature Tl (W is lower than the set value KSTT11W (for example, 20'C). If it is determined that it is low, step 54 is performed.
If it is determined that the value exceeds the set value KSTTHW, the process advances to step 56. In step 54,
Atmospheric pressure is detected, and an atmospheric pressure correction coefficient PPM2STA is determined based on the detected value, and the process proceeds to step 55. The atmospheric pressure correction coefficient PPM28TA is set so that the detected atmospheric pressure is high (yes, a large value).In step 55, the basic injection at startup 1iTsT^ is multiplied by the atmospheric pressure correction coefficient PPM2ST^, and then The value obtained by adding the invalid injection amount 'rsuv to the value is set to a predetermined address TI, and the process proceeds to step 57.In step 56, the value obtained by adding the invalid injection amount 11TsLIV to the basic injection amount TSTA at startup is set to a predetermined address TI. Then, the process proceeds to step 58.In step 57, the fuel injection valve 2 is opened for a time corresponding to the amount set in the address TI to perform fuel injection.In step 58, the fuel injection valve 2 is opened for a time corresponding to the amount set in the address TI. The fuel injection valve 2 is opened for a time corresponding to the amount of fuel to perform fuel injection.

According to such a configuration, the ignition switch 13
When the engine is moved to the start position to start cranking, the basic injection amount at startup is determined based on the engine cooling water temperature at that time (steps 5l-52). If the engine cooling water temperature is lower than the set value, the atmospheric pressure is further detected, and the basic injection amount at startup is corrected to the atmospheric pressure based on the detection result, and the combustion chamber 4 is actually injected into the combustion chamber 4. The final injection amount to be supplied will be determined (
Steps 53-55). When the predetermined fuel injection timing is reached, the fuel injection valve 2 is opened for a time corresponding to the final injection amount to perform fuel injection (step 57). in this case,
It takes several ignition signals from the start of cranking until the actual start of fuel injection.

On the other hand, if the engine cooling water temperature exceeds the set value, the final injection amount is determined based on the basic injection amount at startup and the invalid injection amount, and when the fuel injection time comes, fuel injection is executed immediately. becomes (steps 51-53-56→
58).

The above-described control is then repeatedly executed when the engine is started.

Therefore, with this configuration, when the engine is cold started, the fuel injection amount is corrected to the atmospheric pressure, so it takes some time from the start of cranking until the fuel injection actually starts. However, an air-fuel mixture suitable for the engine condition when cold can be supplied to the combustion chamber 4, and the engine startability when cold is not deteriorated.

On the other hand, if the engine coolant temperature exceeds the set value,
For example, in the case of a high-temperature restart, fuel injection will be performed immediately as soon as cranking starts, so the time from the start of cranking to engine start can be shortened, and It can effectively improve sex.

Note that the set value of the engine cooling water temperature is, of course, not limited to the value shown in the above embodiment, and can be changed as appropriate.

Further, the present invention can be effectively applied to a device that uses an ignition signal to detect engine rotation, etc., and a device that measures the amount of intake air based on the engine rotation speed and intake pressure.

[Effects of the Invention] Since the present invention has the above-described configuration, the process from the start of cranking to the engine start during a high-temperature start such as during a restart can be achieved without deteriorating the engine startability when the engine is cold. It is possible to provide a fuel injection control method at the time of engine starting that can shorten the time and have excellent engine startability.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is a schematic overall configuration diagram, and FIG. 2 is a flowchart diagram schematically showing a control procedure. 2...Fuel injection valve 3...Electronic control unit 12...Water temperature sensor 13...Ignition switch TSTA...Basic injection amount at starting FPMZSTA...Atmospheric pressure correction coefficient

Claims (1)

[Claims] If the engine coolant temperature at the time of engine startup is lower than the set value, atmospheric pressure is detected when the ignition switch is operated to the start position, and the basic injection amount at startup is determined based on the detected value. A fuel injection control method at the time of engine starting, characterized in that the atmospheric pressure correction of the basic injection amount at the time of starting is prohibited when the engine cooling water temperature exceeds the set value. .