JPS5990739A - Control-by-learning of air-fuel ratio of internal-combustion engine - Google Patents

Abstract

PURPOSE:To improve the idling stability at re-starting under high temperature by a method wherein the correction of air-fuel ratio, which has been performed, is controlled to temporarily be stopped at re-starting under high temperature in a system, in which the deviation between the target air-fuel ratio and the base air-fuel ratio is learned and the correction of air-fuel ratio is performed based upon the result of said learning. CONSTITUTION:During the running of an engine 10, the respective output signals from an air flow meter 12, an oxygen sensor 26, an turning angle sensor 32, a water temperature sensor 34 and the like are inputted to an electronic control unit (ECU) 38 in order to calculate basic fuel injection amounts in response to the suction air amounts and the rotational frequencies of the engine 10. In addition, said base fuel injection amounts are corrected by the result of learning, the cooling water temperature and the like, and when air-fuel ratio feedback condition is estabeished, the air-fuel ratio of gas mixture is feedback-controlled in proportion to the deviation between the exhaust air-fuel ratio obtained by the output from the oxygen sensor 26 and the target air-fuel ratio. Furthermore, when learning condition is established, the deviation between the target air-fuel ratio and the basic air-fuel ratio is learned, while at the re-starting under high temperature, the correction of air-fuel ratio, which has been performed based upon the result of learning, is controlled to be temporarily stopped until the feedback control is started.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air-fuel ratio learning control method for an internal combustion engine, and in particular to an exhaust air-fuel ratio learning control method suitable for use in an automatic military engine in which exhaust gas purification measures are taken using a three-way catalyst. Air-fuel ratio learning for an internal combustion engine that performs air-fuel ratio feedback control according to the deviation between the fuel ratio and the target desired fuel-fuel ratio, learns the deviation between the target air-fuel ratio and the base air-fuel ratio, and performs air-fuel ratio correction based on the learning amount. Concerning improvements in control methods.

In internal combustion engines, especially automatic military engines that use three-way exhaust gas purification measures, it is necessary to maintain the air-fuel ratio of the exhaust gas strictly close to the stoichiometric air-fuel ratio. The deviation between the exhaust air-fuel ratio and the target air-fuel ratio is determined using an r# elementary concentration sensor that detects the air-fuel ratio of gas (hereinafter referred to as exhaust air-fuel ratio) and an air-fuel ratio control means that controls the air-fuel ratio of the air-fuel mixture. In addition to performing air-fuel ratio feedback control according to the
Does it depend on the amount of learning? An air-fuel ratio learning control method for an internal combustion engine that performs F-ratio correction has been proposed.

According to such an air-fuel ratio learning control method, the air-fuel ratio is learned and corrected in accordance with environmental conditions, individual differences in various sensors for detecting the engine operating state, and yearly changes. Therefore, it is possible to perform good air-fuel ratio control.
It has Lf characteristics.

However, at high water, the υ base air-fuel ratio becomes rich due to fuel vapor from the fuel tank, so the learning amount is learned to correct the air-fuel ratio to the lean side. On the other hand, if the engine is left running when it is running high, the temperature inside the engine room will become high, causing the fuel in the fuel passage to become bubbles. Totoru.

Therefore, when restarting at a high temperature, even though the υ base air-fuel ratio temporarily becomes lean due to fuel bubbles in the fuel passage, the learning amount further corrects the air-fuel ratio to the lean side, so that the engine This had the problem of poor idle stability.

The present invention has been made to solve the above-mentioned conventional drawbacks, and an object of the present invention is to provide an air-fuel ratio learning control method for an internal combustion engine that can improve idle stability during high-temperature restart.

The present invention performs air-fuel ratio feedback control according to the deviation between the exhaust air-fuel ratio and the target air-fuel ratio, learns the deviation between the own running air-fuel ratio and the pace air-fuel ratio, and performs air-fuel ratio correction based on the learning amount. In the air-fuel ratio learning control method for an internal combustion engine, as shown in FIG.
The above objective has been achieved.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an electronically controlled fuel injection system that senses an intake air amount for an automobile engine will be described in detail below with reference to the drawings, in which an air-fuel ratio learning control method for an internal combustion engine according to the present invention is adopted.

As shown in FIG. 2, this embodiment includes an air flow meter 12 for detecting the flow rate of intake air taken in by an air cleaner (not shown), and a slot/tor body 14.
A throttle valve 16 for controlling the flow rate of intake air, which is opened and closed in conjunction with an accelerator pedal (not shown) disposed at the driver's seat, and a throttle valve 16 for preventing intake air interference. A surge tank 18, an injector 22 arranged for each cylinder of the intake manifold 20 for injecting fuel toward each intake boat of the engine 10, and ignition of the air-fuel mixture introduced into the engine combustion chamber 10a. and an oxygen sensor (hereinafter referred to as "oxygen sensor") disposed in the exhaust manifold 24 for detecting the rich-lean state of the air-fuel ratio based on the residual oxygen concentration in the exhaust gas.
26 (referred to as a zero sensor) 26, a destroyer 28 having a destroyer shaft that rotates in conjunction with the rotation of the crankshaft of the engine 10, and a cylinder discrimination signal and A cylinder discrimination sensor 30 and a rotation angle sensor 32 that output a rotation angle signal, a water wetness sensor 34 installed in the cylinder block 10b of the engine 10 to detect the engine cooling water temperature, and an intake sensor for the output of the air flow meter 12. The basic injection amount for one stroke of the engine reflex is calculated according to the engine rotational speed determined from the air flow rate and the rotational angle signal output from the rotational angle sensor 32, and this is used as the learning amount described later and the water wetness sensor 34. It is corrected according to the output engine cooling water temperature, etc., and when the air-fuel ratio feedback condition is satisfied, the above-mentioned 0! The air-fuel ratio of the air-fuel mixture is feedback-controlled according to the deviation between the exhaust air-fuel ratio and the target desired fuel-fuel ratio detected using the sensor 26, and a valve opening time signal corresponding to the determined fuel injection amount is sent to the injector 22. At the same time, when the learning condition is met, the deviation between the target air-fuel ratio and the base air-fuel ratio is learned, and when restarting at a high temperature, the air-fuel ratio correction based on the learning amount is temporarily stopped until feedback control is started. It is comprised of an electronic control unit (hereinafter referred to as ECU) 38.

As shown in detail in FIG. 3, the ECU 38 includes a central processing unit (hereinafter referred to as MPU) 40, which is made up of, for example, a microprocessor and which performs various arithmetic operations, and the air flow meter, which is inputted via a buffer 42. 1
2 outputs, a multiplexer 46 for sequentially inputting several outputs of the water temperature sensor 34, etc. input via a buffer 44;
, an analog-to-digital converter (hereinafter referred to as an A/D converter) 48 for converting the analog signal output from the multiplexer 46 into a digital signal, and the A/D converter'a
the first input/output port 50 for inputting the output of 48 to the MPU 40; 30 and rotation angle sensor 32 into the MPU 40, and a read-only memory (hereinafter referred to as PO) for storing control programs, various data, etc.
A random access memory (referred to as O12) 60 and a random access memory (referred to as O12) for temporarily storing calculation data etc. in the MPU 40
(hereinafter referred to as RAM) 62, a clock 64, an output port 8 for outputting a valve opening time signal to the injector 22 via a drive circuit 66 according to the calculation result in the MPU 40, and each of the above components. It consists of a common bus 70 that connects devices.

The action will be explained below.

FIG. 4 shows the flow of the main routine in this embodiment. In this main routine, step 101
In step 102, the input/output boat is initialized, and then in step 102, the RAM 62 is cleared and initial data is set. Next, the process proceeds to step 103, where it is determined, for example, based on the output of the water temperature sensor 34, whether or not the engine 10 is in a high operating state, for example, at a temperature of 100° C. or higher. If the determination result is positive, the process proceeds to step 104, where it is determined whether or not air-fuel ratio feedback control is already being executed. If the determination result in step 103 is negative, or if the determination result in step 104 is positive, the process proceeds to step 105, where air-fuel ratio correction is performed using the learning amount.

On the other hand, if the determination result in step 104 is negative, the process proceeds to step 106, where, for example, the learning amount correction coefficient is set to the base unit value 1, so that air-fuel ratio correction based on the learning amount is not performed.

After completing step 105 or 106, step 10
Proceed to step 7, and determine whether the air-fuel ratio condition is satisfied. If the determination result is positive, J'lj
For example, if the engine cooling water temperature is 40°C or higher and the increase/decrease correction is not performed, ~Step 1
Proceeding to step 08, it is determined whether feedback control is already being executed. If the determination result is negative, the process proceeds to step 109, where it is determined whether the air-fuel ratio sensed by the oxygen sensor 26 is equal to or not. If the determination result is positive, step 1. l Go to O, engine 10
It is determined whether or not the is in the high-yield 1 state. If the determination result in steps 108 and 110 is positive or the determination result in step 109 is negative, step 111 is performed and the air-fuel ratio feedback correction coefficient is adjusted according to the output of the O sensor 26. and executes air-fuel ratio feedback processing.

On the other hand, if the determination result in step 107 or 110 is negative (44), the process proceeds to step 112, where, for example, the air-fuel ratio feedback correction coefficient is set to the reference value 12 (thus, the open process is executed).

After completing step 111 or 112, step 11
Proceed to step 3 and calculate the fuel injection time. Then step 1
l on 14! ” and determine whether the learning condition is established. If the determination result is positive, for example, the engine cooling water temperature is 70°C or higher, no monthly correction has been performed, and the air-fuel ratio is step by step ((If it is not the changed air-fuel ratio and is not decelerating, proceed to step 115, learn the deviation between the target air-fuel ratio and the pace air-fuel ratio at that time, and find the learning amount correction coefficient. After step 115 is completed, or if the determination result in step 114 is negative, the process returns to step 103.

In this embodiment, since the air-fuel ratio correction based on the learning amount at the time of Takafuchi restart is stopped until the air-fuel ratio feedback control is executed, the air-fuel ratio is brought close to the stoichiometric air-fuel ratio by the feedback control. Good idling stability can be reliably obtained since the air-fuel ratio correction based on the learning amount is not stopped at the moment when the amount of learning is reached. Note that the method of restarting the 9 fuel ratio correction using the learning amount at the time of Takabuchi restart is not limited to this, for example, it is also possible to restart the air fuel ratio correction using the learning μ: after a predetermined time has elapsed since the high temperature restart. .

In the above embodiment, the present invention is applied to an automatic military engine equipped with an electronically controlled fuel injection device that senses the amount of intake air. However, the scope of application of the present invention is not limited to this, and It is obvious that the present invention can be similarly applied to an automobile engine equipped with a sensing electronically controlled fuel injection system or an internal combustion engine equipped with a general 9 fuel ratio control system.

As described above, according to the present invention, the idling stability at the time of high temperature restart can be improved, which is an excellent effect.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing the gist of the air-fuel ratio learning control method for an internal combustion engine according to the present invention, and FIG. FIG. 3 is a block diagram illustrating the configuration of an electronic control unit used in the above embodiment; FIG. Similarly, FIG. 4 is a flowchart showing the main part of the main routine. 10...Engine, 12...Air flow meter, 2
2... Injector, 26... Oxygen concentration sensor, 2
8... Distributor, 32... Rotation angle sensor,
34... Limescale sensor, 38... Electronic control unit. Agent Takaya Rontu l Figure

Claims (1)

[Claims] (1) Internal combustion system that performs air-fuel ratio feedback control on the exhaust according to the deviation between the fuel ratio and the target air-fuel ratio, learns the deviation between the target air-fuel ratio and the base air-fuel ratio, and performs air-fuel ratio correction based on the learning amount. In the engine air-fuel ratio learning control method,
Air-fuel ratio learning control method for an internal combustion engine 0, characterized in that when restarting Takafuchi, air-fuel ratio correction based on the learning amount is temporarily stopped.