JPS59115436A - Air-fuel ratio controller - Google Patents

Abstract

PURPOSE:To control the air-fuel ratio to the value thinner than the theoretical air-fuel ratio with high accuracy by installing an oxygen concentration detector at the part in a combustion chamber where the thick combustion gas can be detected and feedback-controlling the air-fuel ratio on the basis of the detection signal. CONSTITUTION:An injector 15 into which the fuel sent under pressure from a fuel pump 14 part is supplied is installed into a subcombustion chamber 13. In said subcombustion chamber 13, an oxygen concentration detector 16 is installed so that the detection part is exposed to the combustion chamber 13. The detection signal supplied from said detector 16 is supplied as the air-fuel ratio detection signal into an engine controller 17. By installing the oxygen concentration detector 16 at the position where the concentration of the mixed gas is thick such as in the subcombustion chamber 13, the ratio of volumes of the subcombustion chamber and a main combustion chamber is set, for example, at 1:1, and then the air fuel ratio in the main combustion chamber is shown by lambda 2.0. Thus, the air-fuel ratio can be correctly controlled into lean state.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air-fuel ratio control device that enables feedback control of the air-fuel ratio of an internal combustion engine in a region thinner than the stoichiometric air-fuel ratio.

When performing feedback control of the air-fuel ratio in internal combustion engines such as automobile engines, it is necessary to detect the oxygen concentration in the combustion gas. Oxygen concentration detectors are being installed at The oxygen concentration detector used here has a characteristic that its output changes suddenly at the stoichiometric air-fuel ratio.Using this characteristic, feedback control of the air-fuel ratio can be effectively performed in the region near the stoichiometric air-fuel ratio. I try to do it.

However, in actual automobile engines, the relationship between the stoichiometric air-fuel ratio and the running fuel consumption is as shown in FIG.

Therefore, in a state where feedback control of the air-fuel ratio is effectively performed only in the region near the stoichiometric air-fuel ratio as described above, an air-fuel ratio thinner than the stoichiometric air-fuel ratio that improves driving fuel efficiency (for example, as shown in Figure 1) It was extremely difficult to control the air-fuel ratio (shown as A).

This invention was made in view of the above points, and it is possible to control the air-fuel ratio to be higher than the stoichiometric air-fuel ratio (lean) so that exhaust gas and fuel efficiency measures can be effectively implemented. The present invention aims to provide an air-fuel ratio control device that enables more effective internal combustion engine control.

That is, in the air-fuel ratio control device according to the present invention, an oxygen concentration detector is installed in a part where dense combustion gas corresponding to a combustion chamber such as an auxiliary combustion chamber can be detected, and a detection signal from this detector is used as a feedback signal. By using it as
This enables accurate feedback control of the air-fuel mixture in the combustion chamber to an air-fuel ratio that is even thinner than the stoichiometric air-fuel ratio.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 shows a portion corresponding to one cylinder of an automobile engine, for example. A sub-combustion chamber 13 is provided in communication with the cylinder 12 of the engine 1, and this sub-combustion chamber 13KU An injector 15 is provided to which fuel is supplied under pressure from a fuel pump 14.

In addition, a detection section is provided in this sub-combustion chamber 13.
An oxygen concentration detector 16 is installed so as to be exposed inside the engine, and a detection signal from this detector 16 is supplied to an engine control device 17 as an air-fuel ratio detection signal. This engine control device 17 further includes an engine rotation speed determination signal from a distributor 18, an air flow meter 1
The intake air amount signal etc. from the injector 9 are supplied, and a command is given to the injector 15 to control the amount of fuel injected, thereby controlling the engine 11 in accordance with its operating condition. Although not particularly shown in the figure, the auxiliary combustion chamber 13 is provided with an ignition plug, which ignites the air-fuel mixture within the auxiliary combustion chamber 13 in accordance with the engine rotation angle.

That is, the engine control device 17 receives the rotation speed determination signal,
Based on the intake air amount signal, etc., the injector 15 is controlled to inject fuel commensurate with the intake air amount. In this case, a deviation from the set air-fuel ratio is detected based on the detection signal from the oxygen concentration detector 16, and the engine control device 17 corrects the fuel injection drive signal to the injector 15 in accordance with this deviation, so that the air-fuel ratio is adjusted to the set air-fuel ratio. Feedback control is performed.

Here, as described above, the oxygen concentration detector 16 has a characteristic that its output changes suddenly at the stoichiometric air-fuel ratio, and the engine is controlled at the stoichiometric air-fuel ratio.

As in the past, when an oxygen concentration detector is installed in the exhaust manifold to detect exhaust combustion gas and detect the stoichiometric air-fuel ratio (excess air ratio λ-1), the exhaust gas that increases the air-fuel ratio , it is difficult to control fuel efficiency measures.

However, as shown in the embodiment, the oxygen concentration detector 16 is installed at a position where the air-fuel mixture is rich, such as in the sub-combustion chamber 13, to detect the combustion gas in the combustion chamber. Then, as shown in (4) in FIG. 3, the output signal from the oxygen concentration detector 16 that changes between the upper limit level V and the lower limit level VL is compared with the set level of the seven people. The stoichiometric air-fuel ratio (
λ=1). In this case, if the volume ratio of the sub-combustion chamber to the main combustion chamber is, for example, 1:1, the air-fuel ratio of the main combustion chamber will be approximately 2.0 in λ.

Therefore, the auxiliary combustion chamber 13 is detected by the oxygen concentration detector 16.
By detecting the air-fuel ratio within the engine and feeding back the fuel injection amount to the stoichiometric air-fuel ratio, the air-fuel ratio of the entire engine can be accurately controlled to a lean state.

If the air-fuel ratio can be controlled up to A shown in Figure 1, fuel efficiency will be improved, and as is clear from Figure 4, the exhaust concentration of Co, Hc, and Nox can be sufficiently reduced. Become.

As shown in the embodiment, when the oxygen concentration detector 16 is installed correspondingly inside the combustion chamber, the injected fuel may adhere to the detection part of the detector 16, resulting in a situation in which measurement cannot be performed. .

However, in such a case, the oxygen concentration detector 16 may be installed at a position that is retracted from the wall surface of the combustion chamber so that the injected fuel does not directly hit the detection section.

6- In addition, even if measures are taken to set the position of the detector, if the injected fuel adheres to the oxygen concentration detector 16, the detector 16 should be removed as shown in the figure in Fig. 5. A protective cover 20 made of platinum, stainless steel or ceramic may be formed around the outer periphery of the detection portion 76h.

Alternatively, as shown in FIG.
A heating wire 2 such as a nichrome wire may be installed on the outer circumferential surface of the fuel cell 2, and heated under the control of the engine control device 17 or the like to quickly burn the adhering fuel.

Furthermore, in order to effectively protect the oxygen concentration detector 16 when the combustion chamber temperature rises abnormally, a cooling water passage 22 is formed inside the cover 20 as shown in FIG. 6(C). It will be effective if you do this. That is, when the combustion chamber temperature rises above a set temperature, a signal from a combustion chamber temperature sensor (not shown) is given to the engine control device 17,
A solenoid valve 23 that controls cooling water by this control device 17
This is to open it. Of course 7- Detector, 17...Engine control device〇, solenoid valve 23
Alternatively, the cooling water pump, etc. may be controlled.

As described above, according to the present invention, an oxygen concentration detector is installed to detect rich combustion gas corresponding to the combustion chamber, and the detection signal is also feedback-controlled to set the stoichiometric air-fuel ratio. This makes it possible to effectively control the air-fuel ratio to a state that is leaner than the stoichiometric air-fuel ratio, and it is extremely effective not only for fuel efficiency measures but also for exhaust gas measures. .

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship of the air-fuel ratio to fuel efficiency, FIG. 2 is a diagram explaining the configuration of the engine section of an air-fuel ratio control device according to an embodiment of the present invention, and FIG. 4 is a diagram showing the air-fuel ratio in the above embodiment. Figure 5 (4) is a diagram explaining the state of exhaust gas for
) to (C) are diagrams each illustrating an aspect of the oxygen concentration detector used in the above embodiment. 1. Engine, 12. Cylinder, 13.
Sub-combustion chamber, 15... Injector, 16... Cumulative acid concentration 8- Applicant's agent Patent attorney Takehiko Suzue 9- Mr. Kazuo Wakasugi, Commissioner of F. Soutato Patent Office 1. Indication of the case Japanese Patent Application No. 57-225319 2, Name of the invention Air-fuel ratio control device 3, Person making the amendment Relationship to the case Patent applicant (426) Nippondenso Co., Ltd. 4, Agent March 29, 1988 6. Target of correction 4. Brief description of the drawings FIG. 1 is a diagram showing the relationship between the air-fuel ratio and the fuel efficiency, and FIG. 2 is a diagram explaining the configuration of the engine section of the air-fuel ratio control device according to an embodiment of the present invention. (N and D) in FIG. 3 are waveform diagrams showing the output signal from the oxygen concentration detector and the control signal for this output signal, respectively, and FIG. (A) to (Q in FIG. 5 are diagrams explaining the state, respectively, are diagrams explaining aspects of the oxygen concentration detector used in the above embodiment. 1) Engine, 12 Cylinder , 13...
Sub-combustion chamber, 15... Injector, 16... Oxygen concentration detector, 17... Engine control device.

Claims (1)

[Claims] In an internal combustion engine control device that controls optimal fuel injection by detecting an engine rotation determination signal, an intake air amount signal, an oxygen concentration detection signal, etc., the oxygen concentration detector that detects the oxygen concentration is installed in the combustion chamber of the engine. An air-fuel ratio control device, characterized in that it is installed in a corresponding part and is capable of setting combustion in a combustion chamber to a stoichiometric air-fuel ratio.