JPS6354889B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electronically controlled fuel injection method for an automobile engine that may use gasoline fuel containing alcohol.

[Prior art] In recent years, engines that are compatible with gasoline-only fuel,
Gasoline mixed with alcohol may be used.

[Problems to be solved by the invention] However, in such engines, gasoline
The basic injection amount of fuel is determined based on the operating parameters of the engine (for example, rotational speed, load, etc. as operating conditions) on the assumption that 100% of the fuel will be used. When used as fuel, the following problems may occur. In other words, alcohol and gasoline have different stoichiometric air-fuel ratios (for example, methanol is 6.5, ethanol is
9.0, gasoline is 14.7. ), when alcohol-containing gasoline fuel is used as the fuel, the basic injection amount based on the operating condition is particularly important during open-loop control when the air-fuel ratio feedback signal is turned off, such as during warm-up or when the throttle valve is fully opened. As a result, the air-fuel ratio deviates significantly from the required value, which causes deterioration in drivability and an increase in the amount of harmful components released.

An object of the present invention is to provide an electronically controlled fuel injection method that can effectively prevent deterioration of drivability and increase in the amount of harmful components released during open loop control, regardless of the alcohol concentration in the fuel. .

[Means for solving the problem] In order to achieve this object, according to the present invention, the average value for a certain period of the basic injection amount of fuel calculated based on the operating parameters of the engine, and the basic injection amount During closed-loop control, the difference or ratio between the average value of the actual injection amount over a certain period determined by correcting it based on the air-fuel ratio feedback signal is stored, and during open-loop control, the increase value based on this difference is used as the basic value. The actual injection amount is determined by adding it to the injection amount or multiplying the basic injection amount by an increase rate based on the above ratio.

[Operation] In the electronically controlled fuel injection method of the present invention, when the same fuel is used during closed-loop and open-loop control, the average value of the basic injection amount over a certain period and the injection amount actually required for the engine Taking advantage of the fact that the difference or ratio between the average value and the average value over a certain period of time is almost the same during closed-loop control and open-loop control, regardless of the alcohol concentration in the fuel, the increase value or ratio based on the difference during closed-loop control is determined. The actual injection amount during open loop control is determined by adding or multiplying the increase rate based on the basic injection amount to the basic injection amount. This results in
The air-fuel ratio during open-loop control is maintained at an appropriate value related to the alcohol concentration, resulting in improved drivability, reduced emissions of harmful components, and improved fuel efficiency.

[Example] Embodiments of the present invention will be described with reference to the drawings.

To roughly explain the entire electronically controlled fuel injection system to which the present invention is applied in FIG. 4 controls the flow rate, and is then supplied to the combustion chamber 9 of the engine body 8 via the surge tuck 5, intake branch pipe 6, and intake valve 7. Combustion chamber 9
The air-fuel mixture combusted in the exhaust valve 1 is used as exhaust gas.
0, and is discharged via the exhaust branch pipe 11.
An electromagnetic fuel injection valve 14 is provided in the intake branch pipe 6 corresponding to each combustion chamber 9. The electronic control unit 15 includes a throttle switch 16 that detects the fully closed state of the throttle valve 4, a water temperature sensor 18 that is attached to the water jacket 17 of the engine body 8, and a water temperature sensor 18 that is installed between the air cleaner 1 and the throttle valve 4 to detect the intake air. An air flow meter 19 detects the air flow rate, an intake air temperature sensor 20 detects the intake air temperature, and the crankshaft is connected to the piston 21 via a connecting rod 22 to detect the rotation angle of the crankshaft, which is decelerated to 1/2. Input signals are received from a rotation angle sensor 23 that detects the rotation angle of the distributor shaft connected thereto, an air-fuel ratio sensor 24 provided in the exhaust branch pipe 11 that detects the oxygen concentration in the exhaust gas, and the like. The rotation angle sensor 23 includes a portion 26 that generates one pulse for every two revolutions of the crankshaft, and a portion 27 that generates a pulse every predetermined crank angle, for example, every 30 degrees. Fuel is force-fed from a fuel tank 30 to the fuel injection valve 14 via a fuel passage 29 by a fuel pump 31. The electronic control unit 15 calculates the fuel injection amount and fuel injection timing based on various input signals, sends a fuel injection pulse to the fuel injection valve 14, calculates the ignition timing, and sends a signal to the ignition coil 32. The secondary current of the ignition coil 32 is sent to a distributor 33. Note that the injection valve 14 is maintained in the open state only while receiving pulses from the electronic control section.

FIG. 2 is a flowchart of control performed in the electronic control section 15 during closed loop control.
In step 35, operating parameters of the engine such as engine rotational speed and intake air flow rate detected by each sensor are read, and in step 36, a basic injection amount is calculated based on these operating parameters.
In step 37, the basic injection quantity is increased or decreased in relation to the feedback signal of the air-fuel ratio sensor 24. That is, when the air-fuel ratio sensor 24 is generating a lean signal, the basic injection amount is corrected so that the actual injection amount increases, and on the other hand, when the air-fuel ratio sensor 24 is generating a rich signal, The basic injection amount is corrected so that the actual injection amount is reduced. Thus, in step 38, the average value of the actual injection amount over a certain period of time is determined. In step 39, the injection valve 14 is driven based on the determined actual injection amount. In step 40, the ratio of the average value of the actual injection amount over a certain period determined in step 38 to the average value over a certain period of the basic injection amount calculated in step 36, that is, the increase coefficient K (=actual injection amount/ basic injection amount)
is calculated, and K is stored in step 41. The RAM (random access memory) that stores K is connected to a backup power source and retains K even when the engine ignition switch is turned off. At step 45, basic ignition timing is calculated based on the engine operating parameters from step 35. step
The basic ignition timing calculated using 45 is the MBT (minimum advance for
best torque: minimum advance angle to obtain the optimum torque). In step 46, the basic ignition timing is corrected based on the increase coefficient K obtained in step 40. The larger the increase factor, that is, the higher the alcohol concentration, the higher the octane number and the lower the amount of nitrogen oxides produced, so the actual ignition timing is advanced in order to increase engine output and improve fuel efficiency. . In order to determine the actual ignition timing from the basic ignition timing and the increase coefficient K, the ROM (Read Only Memory)
In this method, multiple maps related to the amount of corrected advance angle are stored in advance using K as a parameter and the rotational speed and intake air amount as coordinates, and the amount of corrected advance angle determined from this map is added or subtracted from the basic ignition timing to calculate the actual value. It is preferable to determine the ignition timing of the Further, in consideration of reducing the amount of memory, only a representative value of K as a parameter can be selected, but this inconvenience can be avoided by well-known interpolation calculations. step 47
Then, an ignition signal is sent to the ignition coil 32 based on the actual ignition timing determined in step 46. In addition, in the conventional electronically controlled fuel injection method, the basic ignition timing is not corrected by the alcohol concentration in the fuel and is taken as the actual ignition timing, but in this example, the basic ignition timing is is corrected in relation to the alcohol concentration in the fuel, so
This correction can improve engine output and fuel efficiency during closed loop control, and reduce the amount of harmful components released.

FIG. 3 is a flowchart of control during open loop control in which the air-fuel ratio feedback signal is turned off, such as during warm-up and when the throttle valve is fully opened. Steps corresponding to the steps in FIG. 2 are indicated by the same numbers as in FIG. 2 with a subscript b added thereto, and the explanation will be omitted, and only the different parts will be explained. The increase coefficient K stored in step 41 of FIG. Determine ignition timing.

In the conventional electronically controlled fuel injection method, during open loop control, the basic injection amount and basic ignition timing are set at 100% of gasoline, regardless of the alcohol concentration in the gasoline.
Although the actual injection amount and ignition timing are directly based on the stoichiometric air-fuel ratio of %, in the present invention, the basic injection amount and the basic ignition timing are corrected based on the increase coefficient K. The difference or ratio between the injection amount and ignition timing actually required of the engine during open-loop control and the basic injection amount and basic ignition timing are determined in steps 38b and 46b, since they are almost the same as during closed-loop control. The actual injection amount and ignition timing are approximately equal to the injection amount and ignition timing actually required by the engine. In this way, during open-loop control when alcohol-containing fuel is used, improvements in drivability and fuel efficiency, and reduction in the amount of harmful components released are achieved. In addition, in a control example in which the difference between the actual injection amount and the basic injection amount is determined during closed-loop control, instead of the increase coefficient K as the ratio between the actual injection amount and the basic injection amount, a value corresponding to this difference during open-loop control, or a positive or negative A predetermined value is added to the basic injection amount.

[Effects of the Invention] The electronically controlled fuel injection method of the present invention has an average value for a certain period of the basic injection amount during closed loop control and an average value for a certain period of the actual injection amount corrected based on the air-fuel ratio feedback signal. The actual injection amount is determined by adding or multiplying the increase value based on the difference or the increase rate based on the ratio to the basic injection amount during open loop control. As a result, during closed-loop control, a difference or ratio that reflects the stoichiometric air-fuel ratio of alcohol-containing gasoline fuel is determined, and during open-loop control, the basic injection amount is corrected by an increase value based on this difference or an increase rate based on the ratio. The actual injection amount reflects the stoichiometric air-fuel ratio of alcohol-containing gasoline fuel. As a result, the actual injection amount during open-loop control is controlled to reflect the stoichiometric air-fuel ratio of alcohol-containing gasoline fuel, which maintains the air-fuel ratio almost exactly at the required value, improving drivability and purifying harmful components. It has an extremely excellent effect of improving both sexes. Furthermore, since the difference or ratio of injection amounts is determined from the average value over a certain period of time, fluctuations in engine operating parameters depending on operating conditions are absorbed, and air-fuel ratio control during open-loop control is improved. It has an excellent effect of being accurate.

[Brief explanation of drawings]

FIG. 1 is a diagram schematically showing an electronically controlled fuel injection system to which the present invention is applied, FIG. 2 is a flowchart during closed-loop control, and FIG. 3 is a flowchart during open-loop control. 8... Engine body, 14... Electromagnetic fuel injection valve,
15... Electronic control unit, 16... Throttle switch, 18... Water temperature sensor, 19... Air flow meter, 20... Intake temperature sensor, 23... Crank angle sensor, 24... Air-fuel ratio sensor.

Claims (1)

[Claims] 1. In an electronically controlled fuel injection method that supplies gasoline fuel containing alcohol to the intake system of an engine via an electromagnetic injection valve, the average of the basic injection amount of fuel over a certain period of time calculated based on the operating parameters of the engine. During closed-loop control, the difference or ratio between this basic injection amount and the average value for a certain period of the actual injection amount determined by correcting this basic injection amount based on the air-fuel ratio feedback signal is stored, and during open-loop control, this difference is stored. An electronically controlled fuel injection method, characterized in that the actual injection amount is determined by adding an increase value based on the above ratio to the basic injection amount, or by multiplying the basic injection amount by an increase rate based on the ratio.