JPH0223242A - Fuel control device - Google Patents

Abstract

PURPOSE:To take a feedback constant as an air density correction value and to make favorable air-fuel ratio control by continuing air-fuel ratio feedback control when an engine is in the idling state and a vehicle is running. CONSTITUTION:The respective detections signals from a throttle sensor 16 for detecting the opening of a throttle valve 14 disposed in an intake passage 12, an oxygen concentration sensor 22 disposed in an exhaust manifold 20, a top dead center sensor 26 disposed in a distributor 24, a crank angle sensor 28, a car velocity sensor 32 disposed in a transmission 80 and a neutral sensor 34 are input to a digital control circuit 40. On the other hand, a designated control signal is output to an injector 18 from a digital control circuit 40 to control the fuel injection quantity. In this case, when an engine is in the idling state and a vehicle is running, the air-fuel ratio feedback control is continued.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a fuel control device for an automobile, and in particular to a fuel control device that can appropriately supply fuel in response to changes in air pressure when exiting a vehicle in an idling state. Regarding.

[Conventional technology]

Generally, in order to correct the amount of fuel supplied in response to changes in atmospheric pressure, air density measurement is performed, but this requires an expensive sensor, making it difficult to construct a low-cost system.

[Problem to be solved by the invention]

The above conventional technology is a system in which the air-fuel ratio feedback control method in an idling state and a gear in a neutral state performs a feedback operation until a certain number of times or a certain time elapses, and then stops. No consideration is given to changes in atmospheric pressure when the passenger leaves the plane, and after the air-fuel ratio feedback control is stopped, the air-fuel ratio changes due to changes in atmospheric pressure.

Furthermore, when the vehicle runs next time, there is a problem in that drivability deteriorates because the change in air density has not been fully corrected.

The present invention has been made to solve the above-mentioned drawbacks of the conventional technology, and it is possible to learn the air-fuel ratio correction coefficient when the vehicle is idling and the gear position is neutral. It is an object of the present invention to provide a fuel control device for an internal combustion engine that can correct the entire operating range by using a correction value and can perform precise air-fuel ratio control.

[Means to solve the problem]

The above purpose is to detect the speed of the vehicle when it is idling and the gear position is in neutral, and when the speed is above a certain level, to constantly perform air-fuel ratio feedback control.
This is achieved by using the feedback constant as an air density correction value.

[Effect]

When the detected speed of the vehicle is greater than a certain value in the idling state and the gear position is in the neutral state, the following operation is performed on the premise that the air density may change.

The fuel injection amount is feedback-controlled by an air-fuel ratio sensor to maintain it near the stoichiometric air-fuel ratio. Thereby, even if the air density changes, the stoichiometric air-fuel ratio can be maintained at all times. Further, the correction value of the fuel injection amount required to maintain the air-fuel ratio at the stoichiometric air-fuel ratio is reflected in the entire operating range. As a result, when the operating range changes to red, the fuel injection correction amount due to changes in air density can be determined in advance, so that the air-fuel ratio can always be maintained accurately.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

An example of the fuel control device according to the present invention is as shown in FIG.
A throttle valve 14 for controlling the flow rate of intake air, which is disposed in the intake passage 12 and is opened and closed in conjunction with an accelerator pedal (not shown) disposed at the driver's seat; a throttle sensor 16 including a potentiometer that generates a voltage output proportional to the opening degree of the intake passage 12;
an injector 18 disposed therein for injecting fuel;
, an oxygen concentration sensor 22 disposed in the exhaust manifold 20 for detecting the air-fuel ratio from the residual oxygen concentration in the exhaust gas, and a distributor having a distributor shaft that rotates in conjunction with the rotation of the crankshaft of the engine 10. 24, a top dead center sensor 26 and a crank angle sensor 28, which are built in the distributor 24 and output a top dead center signal and a crank angle signal according to the rotation of the distributor shaft, and an output shaft of the transmission 30. A vehicle speed sensor 32 for detecting the running speed of the vehicle from the rotation speed, a neutral sensor 34 for detecting whether the gear disposed in the transmission 30 is in neutral, and a clutch disposed at the driver's seat. In a fuel control device consisting of a clutch contact for detecting whether a pedal (not shown) is depressed, and a digital control circuit 40 for inputting/outputting the above items, the amount of intake air is determined by a throttle sensor. It is calculated from the engine rotation speed determined from the output of the crank angle sensor 16 and the output of the crank angle sensor 28. It is also a fuel control device that supplies fuel commensurate with the amount of intake air to the engine from the injector 38.

Further, the configuration of the digital circuit 40 is as shown in FIG. 2, as shown in FIG.
01, the output 202 of the oxygen concentration sensor 22, and the output 203 of the sensor that detects the engine cooling water temperature.
A circuit 204 for digital conversion, a pulse output 205 of a crank angle sensor 28 built into a distributor 24 attached to the engine 10, and a transmission 30.
A part 208 that counts and processes the pulse output 206 of the vehicle speed sensor 32 attached to the vehicle speed sensor 32 and a circuit 209 that generates pulses to drive the injector 18 for supplying fuel to the engine 10 are used to connect input and output to the outside. It consists of a controlling part. Further, the input/output is controlled by the CPU 211. The qpu211 is a non-volatile memory (
Operations/calculations are performed using programs and data written in the ROM (ROM) 210.

The calculation is performed using a rewritable RAMI 212 and
It consists of a RAM2 213 that can back up the contents of the memory with a battery.

A functional block diagram for performing arithmetic processing within the CPU 211 is shown in FIG.

A basic fuel injection amount 303 is calculated based on the throttle valve opening degree α 301 and the engine speed N 302, and a deviation input 304 between the exhaust gas air-fuel ratio detected from the oxygen concentration sensor output and the target air-fuel ratio is input by the control function 305. The fuel injection amount 306 is determined by adding feedforward and feedback increase/decrease corrections according to the engine operating state to the basic fuel injection amount 303, and the injector drive unit 3
07 drives the injector 18 to supply fuel to the engine.

The operation of the input control function 305 is determined by the input control function stop/continuation determination function 306.゛This person control function stop/continuation judgment function is based on the idle detection bag [1308, vehicle speed 309, and counter 311
Determine whether to stop or continue.

As shown in the flowchart shown in Fig. 4, the function stop/continuation determination of the true entry control is performed using a counter for counting the same number of learned air-fuel ratio deviations.
Next, it is determined whether the throttle valve opening is at the idle position 402, whether the engine rotation speed Ne is smaller than the idle rotation speed detection level IDKRPM 403, and the gear A determination 404 is made as to whether the position is neutral.

If one or more of the determination items is not true, another process is performed, and if all are true, the following process is performed.

Vehicle speed enters control stop level CLr'VSP
If the result is true, the air-fuel ratio deviation is learned 406 and stored in BLRC1, and the process from the judgment operation 402 is repeated. Also, when it is false, it is determined whether the learning counter Counter is greater than the learning completion detection level IDCNT (407), and when it is false, it is incremented by 1 to the learning counter, a learning operation LRC406 is performed, and the process starts from the aforementioned determination operation 402. is repeated, and if true, the input control function is stopped 409, and the process returns to the process of setting the learning counter to φ, and the above operation is repeated.

The above-described operation will be explained by taking as an example the case where the gear is in the neutral position and the engine speed is in an idling state from a high altitude to a low altitude. FIG. 5 shows the relationship between each operation. When the accelerator pedal is turned off, the idle switch is turned on, and when the gear is placed in the neutral position, the neutral switch is turned on. Also at this time,
The idle condition is established when the engine speed becomes equal to or less than ID and RPM. At this point, if controlling the input control function according to the vehicle speed according to the present invention is not used, the air-fuel ratio learning control will be performed IDCNT times, and the driver will be clamped to a certain value. However, since the vehicle is actually going downhill, the air density changes, so the air-fuel ratio A/
F becomes lean.Furthermore, if the vehicle speed according to the present invention is used to perform on-board control based on the vehicle speed when the idle condition is met, the on-board control will continue until the vehicle speed becomes smaller than the on-line control function stop judgment level CLPUSP. Therefore, the air-fuel ratio A/F i-! The stoichiometric air-fuel ratio can be maintained at 14.7. Furthermore, at this time, the increase/decrease obtained through feedback control by the oxygen concentration sensor 22 is set as the air density correction value BLRCl, and the fuel injection pulse width is calculated by the following formula. It is possible to maintain an appropriate air-fuel ratio.

T i = T p X LANDAX KBLRCI
X KBLRC2 where Ti: Fuel injection pulse width TP: Basic fuel injection pulse width LANDA: Feedback increase/decrease KBLRCI: Air density correction value KBLRC2: Learning map value [Effects of the invention] An example of the effects of the present invention is shown in Fig. 6. As shown, altitude 2
When the air-fuel ratio was 14.7 at 500 m, and the gear was idling in the neutral position and the slope was descended to an altitude of 1500 m, the air-fuel ratio A/F without using the present invention would be 16.3. Become a person. On the other hand, the air-fuel ratio A/F when using the present invention is the stoichiometric air-fuel ratio 14.7
It was possible to maintain

[Brief explanation of the drawing]

FIG. 1 is a system configuration diagram of an embodiment of the present invention. Figure 2 is an internal configuration diagram of the digital circuit 40 in Figure 1;
4 is a flowchart of FIG. 3, FIG. 5 is a timing chart of an embodiment of the invention, and FIG. 6 is a diagram showing the effects of the invention. 16...Throttle sensor, 22...Oxygen concentration sensor, quick diagram

Claims (1)

[Claims] 1. In a fuel control device that cannot detect air density, when the engine is in an idling state and the vehicle is running, air-fuel ratio feedback control is continuously performed. Fuel control device. 2. In the first item, it is equipped with an O_2 sensor, and the feedback constant when performing air-fuel ratio feedback control by the O_2 sensor is reflected in the entire operating range to determine the fuel injection amount in the next operating state. Features fuel control device. 3. A fuel control device according to item 1 or 2, which has a vehicle speed sensor and determines whether to continue or stop the air-fuel ratio feedback control based on a signal from the vehicle speed sensor. 4. The fuel control device according to item 3, wherein the fuel control device determines whether to continue or stop the air-fuel ratio feedback control in synchronization with the acquisition of a vehicle speed sensor signal.