JPH076422B2 - Fuel control device - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electronically controlled fuel control device.

[Conventional technology]

In the conventional fuel control device, during acceleration, the output b of the intake sensor becomes larger than the actual engine intake air amount a shown in FIG. 3 (b), and the air-fuel ratio is determined according to the output of the intake air amount sensor. Since the output b of the intake air amount sensor becomes less than the actual intake air amount a during deceleration, the air-fuel ratio became over lean. As a result, drivability deteriorated and emission deteriorated.

In order to solve such a problem, a conventional device shown in FIG. 1 (described in Japanese Patent Application Laid-Open No. 58-25531) has been proposed. In the figure, reference numeral 1 is a four-cycle spark ignition type engine mounted on an automobile, in which combustion air is an air cleaner 2 and an intake pipe 3.
And is inhaled through the throttle valve 4. Further, the output of the control circuit 20 drives the electromagnetic fuel injection valves 51 to 56 to open and supply fuel to each cylinder. The exhaust gas after fuel is discharged to the atmosphere through the exhaust manifold 6, the exhaust pipe 7, and the like. The intake pipe 3 is provided with a potentiometer-type intake air amount sensor 8 that detects an intake air amount taken into the engine 1 and outputs an analog voltage according to the intake air amount. Further, a thermistor type intake air temperature sensor 9 that detects the intake air temperature and outputs an analog voltage according to the intake air temperature is provided. Further, the engine 1 is provided with a thermistor type water temperature sensor 10 that detects the cooling water temperature and outputs an analog voltage according to the cooling water temperature. The rotation speed sensor 11 detects the rotation speed of the crankshaft of the engine 1. , Outputs a pulse signal having a frequency corresponding to the rotation speed. As the rotation speed sensor 11, for example, an ignition coil of an ignition device may be used, and an ignition pulse signal from the primary side terminal of the ignition coil may be used as the rotation speed signal. Further, the throttle valve 4 is provided with an idle switch 12 for detecting that the throttle opening is equal to or less than a set value. The control circuit 20 is a circuit that calculates the fuel injection amount based on the outputs of the sensors 8 to 12, and the fuel injection valve
The fuel injection amount is adjusted by controlling the valve opening time of 51-56.

FIG. 2 shows the details of the control circuit 20, and 200 is a microprocessor (CPU) for calculating the fuel injection amount. Reference numeral 201 denotes a rotation speed counter, which counts the engine rotation speed from a signal from the rotation speed sensor 11. The rotation speed counter 201 gives an interrupt command to the interrupt control unit 202 in synchronization with engine rotation. Upon receiving this instruction, the interrupt control unit 202 outputs an interrupt signal to the CPU 200 via the common bus 212. The digital input port 203 transmits a digital signal such as a starter signal from the starter switch 13 for turning on / off the operation of a starter (not shown) to the CPU 200. The analog input port 204 includes an analog multiplexer and an A / D converter, and includes an intake air amount sensor 8, an intake air temperature sensor 9 and a water temperature sensor.
It has a function to A / D convert each signal from 10 and read it into CPU200 one after another. The output of each unit 201-204 is common bus 21
2 is transmitted to the CPU 200. 205 is a power circuit,
It is connected to the battery 14 through the key switch 15.
206 is RAM, 207 is R for storing programs and various constants
OM, 208 is a fuel injection time control counter including a register, which is a down counter, and is a digital signal indicating the valve opening time of the fuel injection valves 51 to 56 calculated by the CPU 200, that is, the actual valve opening time. Is converted into a pulse signal having a pulse time width. Reference numeral 209 is a power amplifier that amplifies the output of the counter 208 and supplies the amplified power to the fuel injection valves 51 to 56. 210 is a timer, which measures the elapsed time and transmits it to the CPU 200. The rotation speed counter 201 measures the engine rotation speed once per revolution of the engine based on the output of the rotation speed counter 11, and supplies an interrupt command signal to the interrupt control unit 202 at the end of the measurement. The interrupt control unit 202 generates an interrupt signal in response to the signal, and causes the CPU 200 to execute an interrupt processing routine for calculating the fuel injection amount.

Next, the operation of the above device will be described. When the key switch 15 and the starter switch 13 are turned on and the engine 1 is started, the arithmetic processing of the main routine is started, and after initialization,
The cooling water temperature and the intake air temperature are measured, the correction amount K of the fuel injection amount is calculated based on the measured values, and the result is stored in the RAM 206. Then, the same operation is repeated many times. Also, the CPU 200 starts an interrupt process in response to an interrupt signal from the interrupt control unit 202. First, the engine speed N is read, and then the engine intake air amount Q is read. Next, the basic fuel injection amount To calculate. F is a constant. Next, a weighted average process is performed on W, a limit is applied accordingly, W is further corrected by the correction amount K, and fuel injection is performed so that this fuel injection amount is achieved.

[Problems to be Solved by the Invention]

In the above-mentioned conventional device, so-called anneal processing is performed to eliminate over lean or over rich. However, when the engine intake air amount is in transition, there is a large difference between the intake air amount at the time of injection calculation (FIG. 3 (b)) and the intake air amount at the time of closing the intake valve (FIG. 3 (b)). As shown in a), the air-fuel ratio became over lean during acceleration and over rich during deceleration. Therefore, there is a problem that drivability is deteriorated and emission is deteriorated. 3 (c) shows the intake pipe 3
Indicates the internal pressure of.

The present invention has been made to solve the above problems, and an object of the present invention is to obtain a fuel control device capable of performing good operation without disturbance of the air-fuel ratio during acceleration / deceleration. To do.

[Means for Solving the Problems]

A fuel control device according to the present invention comprises means for calculating a basic fuel injection amount, processing means for performing a smoothing process for the basic fuel injection amount, means for calculating a changing speed of the smoothing process value, and fuel injection Since the means for predicting and calculating the smoothed value when the intake valve is closed from the time from the time until the intake valve is closed, the smoothed value and the changing speed thereof, and the means for performing fuel injection by the predicted smoothed value are provided. is there.

[Work]

In the present invention, the smoothing process of the basic fuel injection amount is performed, and the value of the smoothed process value when the intake valve is closed is predicted and calculated. Changes with time are expected.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. The structure of the fuel control device according to this embodiment is as shown in FIGS. 1 and 2.

Next, the operation will be described. When the key switch 15 and the starter switch 13 are turned on and the engine 1 is started,
The calculation process of the main routine is started in step 30 of FIG. 4, initialization is performed in step 31, and in step 32 digital values corresponding to the cooling water temperature and the intake air temperature from the analog input port 204 are read. In step 33, the fuel correction amount K ₁ is calculated from this result, and the result is stored in the RAM 206. When step 33 ends, the process returns to step 32.

When the interrupt signal is input from the interrupt control unit 202, the CPU 200 immediately interrupts the main routine even during the processing of the main routine, and shifts to the interrupt processing routine of FIG. In step 101, a signal representing the engine speed N from the engine speed counter 201 is fetched, and in step 102 a signal representing the intake air amount Q is fetched. In step 103, from the engine speed N, the intake air amount Q and the constant F, The basic fuel injection amount W is calculated by In step 104, the basic injection amount W is corrected, that is, the smoothing process based on the weighted average is performed. The formula is , J is a constant, T is a weighted average processed value, and n is 0, 1, 2, ...
n. In step 105, the interrupt signal interval t ₀ from the rotation speed sensor 11 shown in FIG. 6 and the changing speed of the smoothing process value from the current and previous smoothing process values Tn and Tn ₋₁ calculated in step 104. Is calculated. In Step 106, the injection time and the time t ₁ until the intake valve is closed when the intake amount is finally determined, and the anneal processing value calculated in Step 105 and the rate of change thereof are used to predict the anneal processing value when the intake valve is closed. The value Tout is calculated by the following equation.

In step 107, the predicted value is clipped with the maximum value and the minimum value determined by the capacity of the engine, the number of revolutions, and the high rate so that the predicted value does not become too large or too small. Step 10
In step 8, the second correction amount K ₂ is calculated using the predicted value. This is a correction coefficient which is mapped by, for example, the rotation speed and the smoothing processing value as shown in FIG. 7, and makes the air-fuel ratio thicker to increase the output when operating at high engine speed and high load. . In step 109, the predicted value Tou
t is corrected by the correction amounts K ₁ and K ₂ , and in step 110, the corrected predicted value is set as the injection amount in the counter 208, and the interrupt process ends. Then, the process returns to the processing step before the interruption of the main routine.

〔The invention's effect〕

As described above, according to the present invention, the smoothing process of the basic fuel amount is performed, and the smoothing process value is calculated by predicting the change of the smoothing process value from the time of fuel injection to the time of closing the intake valve, Fuel injection is performed with this value, the air-fuel ratio does not become over lean or over rich during acceleration / deceleration, the drivability becomes good, and the deterioration of emission can be prevented.

[Brief description of drawings]

1 and 2 are an overall configuration diagram of the device of the present invention and a configuration diagram of a control circuit, and FIG. 3 is an explanatory diagram of a problem of the conventional device,
5 and 5 are flowcharts showing the operation of the invention device, FIG. 6 is a time chart showing the operation of the invention device, and FIG. 7 is a data map for calculating the correction amount in the invention device. 1 ... Engine, 8 ... Intake amount sensor, 11 ... Rotation speed sensor, 20 ... Control circuit, 51-56 ... Fuel injection valve. The same reference numerals in the drawings indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A rotational speed detecting means for detecting an engine rotational speed, an intake air amount detecting means for detecting an engine intake air amount, a means for calculating a basic fuel injection amount from the engine rotational speed and the intake air amount, and this basic fuel injection. A smoothing means for performing a smoothing process for the quantity, a means for calculating a changing speed of the smoothing value, an intake air from the time from the time of fuel injection to the closing of the intake valve and the smoothing value and the changing speed thereof. A fuel control device comprising: means for predicting and calculating a smoothed value when the valve is closed; and means for injecting fuel according to the predictively calculated smoothed value.