JPS63140858A - Exhaust gas reflux controller for internal combustion engine - Google Patents

Abstract

PURPOSE:To improve the extent of accuracy, by compensating the output of an oxygen sensor by dint of the oxygen sensor outer circumferential pressure calculated out of suction air quantity and engine speed at the time of performing feedback control over a desired EGR rate on the basis of a tection value of the oxygen sensor installed at the downstream of an EGR passage opening in a suction system. CONSTITUTION:Each detection value out of an engine speed detector 8, a suction quantity sensor 10, the oxygen sensor 18 installed at the downstream of an opening of an EGR passage 11 in a suction pipe 2 and an opening detector 13 of an EGR control valve 12 is inputted into an EGR control circuit 14. This circuit 14 calculates a desired EGR rate and outer circumferential pressure of the oxygen sensor 8 on the basis of suction air quantity and engine speed, and controls the EGR control valve 12 for feedback so as to secure the oxygen content conformed to the desired EGR rate on the basis of calculation of the oxygen sensor 18 compensated by this desired EGR rate and the outer circumferential pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an engine exhaust gas recirculation control device that controls the amount of exhaust gas recirculation in an internal combustion engine.

[Conventional technology]

It is well known that exhaust gas recirculation, in which a portion of the exhaust gas is introduced into the intake side of the engine, is carried out in order to reduce nitrogen oxides, which are harmful components in the exhaust gas of an internal combustion engine.

In addition to reducing nitrogen oxides, the flow rate of the recirculated exhaust gas affects engine performance and fuel efficiency, so it is desirable that the flow rate of the recirculated exhaust gas be precisely controlled according to the operating conditions of the engine. .

FIG. 6 is a schematic diagram of a conventional optical exhaust gas recirculation control transfer system disclosed in, for example, Japanese Patent Laid-Open No. 55-93950. In the figure, (1) is the engine body, (2) is the intake manifold, 13) is the Vi exhaust manifold, (4) is the 9 fuel supply system installed in the intake manifold (2), +
51 Vi throttle valve, (8) is intake tact, (
1) is the air cleaner, (8) is the engine speed detector,
(9) is the negative pressure introduction passage, the line is the intake air flow rate sensor that detects the amount of air taken in by the engine, and the line is the exhaust gas recirculation (hereinafter referred to as "exhaust gas recirculation") that connects the exhaust manifold (3) and intake manifold (2). 1gGR) passageway, α'4
is operated by the pressure diaphragm (EGR control valve, a is the EGR control valve)
The opening degree detector for the control valve 0, (I4 is the KGRtfdJ control circuit, (l fathom is the atmospheric pressure introduction passage, and 0 is the output signal sent from the KGB @control circuit α) determines the closing degree of the EGR control valve α. Control the negative pressure by intake negative pressure and atmospheric pressure!
This is a controlled negative pressure generator that regulates the pressure.

In the nine EGR control device configured in this way, the following steps are performed:
/The engine rotation speed Nll1 indicating the engine operating state and the large intake flow rate are detected by the engine rotation speed detector (8) and the air flow rate sensor (lot), and the EGR control circuit 04
is input.

EGR control circuit (+41 is an EGR control circuit that is determined depending on the engine operating state, that is, the engine speed and intake flow rate.
A target opening degree of the control valve (+2) is set, and a control negative pressure generator is used to make the comparison deviation between this target opening degree and the actual opening degree inputted via the opening degree detector 1 to zero. (16>). That is, based on the output signal sent by the EGR control circuit (141), the output negative pressure at the control negative pressure generator end is regulated by the intake negative pressure and atmospheric pressure, and the EGR control valve (The opening degree of the KGB control valve 02 is determined by controlling the opening degree of the exhaust gas and determining the amount of exhaust gas recirculation (hereinafter referred to as the EGR amount) that makes the comparison deviation in #1 zero. By performing feedback control using the output of the opening degree detector 01, an EGR amount corresponding to the operating state of the engine is obtained.

[Problem that the invention seeks to solve]

However, according to such a conventional EGR control device, when the EGR control valve 02) is used for a long time, a large amount of carbon, etc. contained in the exhaust gas adheres to this valve.
Initial EGRi corresponding to the opening/closing degree of EGR control valve 021
There is a problem in that l changes and accurate control is no longer possible.

The present invention has been made in view of these points, and its purpose is to provide an exhaust gas recirculation control device for an internal combustion engine that enables highly accurate recirculation control that does not change over time. be.

[A precautionary measure to resolve the problem]

An exhaust gas recirculation control device for an internal combustion engine according to the present invention includes nine exhaust gas recirculation control valves provided in an exhaust gas recirculation passage that communicates an exhaust system and an intake system of an internal combustion engine, and an exhaust gas recirculation passage opening in the intake system. an oxygen sensor provided further downstream to detect the oxygen concentration in intake air; an intake air amount sensor provided in the intake system of the engine to detect the amount of air taken in by the engine;
A rotation speed detector detects the rotation speed of the engine, and a target oxygen concentration corresponding to the target exhaust gas recirculation rate is provided to achieve a predetermined target exhaust gas recirculation rate corresponding to the operating state of the engine. and corrects the output signal of the oxygen sensor with the calculation amount corresponding to the external ambient pressure calculated from the output signals of the intake air amount sensor and rotation speed detector, and corresponds to the oxygen concentration after this correction. The above exhaust g is calculated according to the deviation between the calculated amount x and the calculated amount corresponding to the above target oxygen concentration.
, and exhaust gas recirculation control means for adjusting the opening and closing of the J5 gas recirculation control valve.

[Effect]

In this invention, the output signal of the oxygen sensor is calculated from the output signals of the intake AT sensor and the rotation speed detector, and the output signal of the oxygen sensor is corrected by the calculation amount corresponding to the unexpected ambient pressure, and the output signal of the oxygen sensor is calculated from the calculation amount corresponding to the corrected oxygen concentration. The opening and closing of the exhaust gas recirculation control valve is adjusted while grasping the actual oxygen concentration according to the deviation from the calculation amount corresponding to the target oxygen concentration predetermined according to the engine operating condition, so that changes over time can be avoided. This enables highly accurate reflux control that eliminates reflux.

〔Example〕

Embodiments of an exhaust gas recirculation control device for an internal combustion engine according to the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing the configuration of one embodiment. This first
In the figure, parts that are the same as those in FIG. 6 are given the same reference numerals, and parts that are different from those in FIG. 6 will be mainly described.

As is clear from comparing Figure 1 with Figure 6,
In the figure, the parts indicated by the symbols +1) to slope are the same as those in Fig. 6, and the parts indicated by the symbols 0η and onwards are newly provided parts from this Fig. 1, and are the features of this invention. It is.

In other words, the intake pipe (2) of the EGR passage (II)
opening to (1 barrel has an intake pipe downstream of this opening Q) (
2) is an oxygen sensor installed in This oxygen sensor 0
Reference numeral 1 detects the oxygen concentration in the intake air flowing through the intake pipe (2). This type of oxygen sensor generates a sensor output proportional to the oxygen concentration.

The output of this t-sparse sensor t1@ is the IGR control circuit (14
). The other configurations are the same as in FIG. 6.

Next, the operation of the above embodiment will be specifically explained with reference to FIGS. 2 to 4. Figure 2 a shows oxygen concentration C0
Fig. 2 is an explanatory diagram showing the relationship between oxygen sensor a and the output of the oxygen sensor.
An explanatory diagram showing how the level of output I is slightly changed. Figure 3 is an explanatory diagram showing the relationship between EGR''4AK and the oxygen concentration cam in the intake air. Figure 4 is an explanatory diagram showing the relationship between EGR''4AK and the oxygen concentration cam in the gGR control circuit.
Nine target IGR rates K are determined corresponding to the internally stored operating conditions of the engine.

FIG.

When the engine body (11) is started, the engine body (11) is started.
) The engine rotation speed N indicates the operating state of the engine. The large intake flow rate of the engine is detected by the engine rotation speed detector (8) and the air flow rate sensor (seaweed) and is input to the IGR control circuit 114.

In this EGR control circuit 04, as shown in FIG. 4, a target EGR rate K corresponding to the rotational speed NIC and the intake air flow rate A is stored.

is stored, and a target EGR rate Kol, for example, is selected according to the values of the rotational speed and intake flow rate A.

Target oxygen concentration Co2 corresponding to this target EGR rate KOi
1 is calculated according to FIG.

On the other hand, the oxygen concentration of the air mixed with EGR gas in the intake pipe (2) is calculated from the output l of the oxygen sensor (l barrel), but the pressure during intake 'IF t21 is calculated from the throttle valve (l). 6) The opening/closing degree and the engine rotation speed are 1.
1. Under normal operating conditions, the pressure constantly fluctuates within a range from atmospheric pressure to about 1,700 Hg.

The relationship between the output I at the oxygen sensor end and the oxygen concentration is as shown in Fig. 2. When the pressure around the sensor is constant, an output level proportional to the oxygen concentration can be obtained. When the total pressure around the outside changes, the output level changes slightly as shown in Figure 2, even though the oxygen concentration is constant.

On the other hand, when the air flow rate is A and the engine speed is NM with respect to the external ambient pressure P of the oxygen sensor, A/N.

When the EGR rate is 4, a 1:1 proportional relationship is obtained as shown in Figure 5a when the EGR rate is 4. , and the ratio of A/Nl to P* obtained by changing the EGR rate is as shown in FIG. 5. The correspondence relationship between these two is stored in the IGR control circuit (14), and in this circuit α, the output Ip of the oxygen sensor (c) and the air flow rate sensor (101 and rotation speed detector (8)) are stored. The above signals A and NIc are input, and the oxygen concentration is calculated taking into account the diagram in FIG.

pressure P as shown by the solid and broken lines in Figure 2a.
The oxygen concentration Co2 is calculated by correcting the equation.

This calculated nine oxygen concentration Cog and the target oxygen concentration Co
gi, and based on the comparison deviation, the output negative pressure of the gGR control circuit I, the output negative pressure of the control negative pressure generator 0, and the pressure of the intake negative pressure introduction passage (9) and the atmospheric pressure introduction passage O5l are determined. The opening and closing degree of the EGR control valve (I) is driven and controlled, and the EGR gas amount is controlled to al* so that there is no comparative deviation.

In the above embodiment, the gGR control valve a is configured to be driven by negative pressure via the pressure converter 7 ram, but it may be configured to be driven by electric power.

Further, the opening degree detector TJ1 may not be provided.

The EGR control circuit (14) is composed of an electronic circuit including an electrical memory circuit, and although the internal configuration is analog, it can also be composed of an analog-to-digital converter, a microcontroller, and a controller. It may also be a zygittal type.

Please note that in the above embodiment, the target KGR rate is calculated from the engine speed NE and the intake air flow rate A, but the target KGR rate is not limited to this. A similar effect can be obtained when searching.

〔Effect of the invention〕

As described above, according to the present invention, the exhaust gas recirculation control valve provided in the next exhaust gas recirculation passage that connects the exhaust system and the intake system of an internal combustion engine, and the An oxygen sensor is installed in the engine to detect the concentration of one element in the intake air, and an intake air sensor is installed in the intake system of the engine to detect the amount of air taken into the engine. Calculate the amount of calculation corresponding to the target oxygen concentration according to the target exhaust gas recirculation rate so that the detector and the target exhaust gas recirculation rate will reach the standard exhaust gas recirculation rate predetermined according to the operating state of the engine, and the above-mentioned The output signal of the oxygen sensor is corrected by the calculation amount corresponding to the external ambient pressure calculated from the output No. 1 of the intake air amount sensor and the rotation speed detector, and the calculation amount corresponding to the corrected oxygen concentration and the target oxygen concentration are calculated. and an exhaust gas recirculation control means that adjusts the opening and closing of the exhaust gas recirculation control valve according to the deviation from the calculated amount X corresponding to the exhaust gas recirculation control valve.
This has the effect of enabling highly accurate exhaust gas recirculation control that does not change over time.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the exhaust gas recirculation control device for an internal combustion engine according to the present invention, and FIG.
Figure 2 is a characteristic diagram showing the relationship between the oxygen sensor output Ip and Figure 2.A characteristic diagram showing the relationship between the oxygen sensor and the external ambient pressure Pa for explaining the exhaust gas recirculation control system for the same internal combustion engine as above; Figure 3 is a characteristic diagram showing the relationship between the oxygen concentration in the intake air and the KGR rate in the exhaust gas recirculation control device of the internal combustion engine,
Fig. 4 is a characteristic diagram showing the relationship between @g EGR rate Ko and engine speed NE in the exhaust gas recirculation control system of the same internal combustion engine, and Fig. 5 a shows the calculation amounts A/N and B when the KGR rate is zero. FIG. 5 is a characteristic diagram showing the relationship between the calculation amount A/NIC and the outside ambient pressure f's for KGR4, and FIG. FIG. 1 is a configuration diagram showing an exhaust gas recirculation control device for an internal combustion engine. Il)...Engine body, (2)...Intake pipe, (3
)...Exhaust pipe, (5)...Throttle valve, (8)...
...Engine speed detector, (field...air flow rate sensor, (Il)...EGR passage, 0 odor...KGB control valve, H...KGB control circuit, state...oxygen sensor. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] An exhaust gas recirculation control valve provided in an exhaust gas recirculation passage that communicates an exhaust system and an intake system of an internal combustion engine; an oxygen sensor that detects the oxygen concentration of the engine; an intake air amount sensor that is installed in the intake system of the engine and detects the amount of air taken into the engine; a rotation speed detector that detects the rotation speed of the engine; Calculates the amount of calculation corresponding to the target oxygen concentration according to the target exhaust gas recirculation rate so that the target exhaust gas recirculation rate is predetermined according to the state, and calculates the calculation amount corresponding to the target oxygen concentration according to the target exhaust gas recirculation rate, and The output signal of the oxygen sensor is corrected with the calculation amount corresponding to the external ambient pressure calculated from the output signal, and the output signal of the oxygen sensor is corrected according to the deviation between the calculation amount corresponding to the corrected oxygen concentration and the calculation amount corresponding to the target oxygen concentration. an exhaust gas recirculation control device for an internal combustion engine, comprising: exhaust gas recirculation control means for adjusting opening and closing of the exhaust gas recirculation control valve. (2) The calculation amount corresponding to the external ambient pressure is, when A is the intake flow rate obtained from the output signal of the intake air amount sensor, and N_E is the rotation speed obtained from the output signal of the rotation speed detector.
The exhaust gas recirculation control device for an internal combustion engine according to claim 1, wherein the exhaust gas recirculation control device for an internal combustion engine is calculated as A/N_E.