JPH01130051A - Exhaust gas recirculation system for internal combustion engine - Google Patents

Abstract

PURPOSE:To improve the accuracy of control with a simple circuit by decreasing a learning value if EGR valve opening is more than the specified value, but increasing the learning value if it is less than the specified value, when learning conductions are materialized. CONSTITUTION:Each detected value of an air flow meter 13, a cooling water temperature sensor 28, a valve opening detecting switch 45 being turned to ON when an EGR valve 3 is lifted to the specified value, a turning angle sensor 54, a car speed sensor 79, etc., is inputted into a control circuit 52, and thereby lift of the EGR valve 36 is controlled via a vacuum switching valve 40. When the control circuit 52 judges a steady driving state that any of car speed, intake air quantity and engine speed is within the specified range, it discriminates whether the valve opening switch 45 is on or off. When it is on, a learning value to the vacuum switching valve 40 is decreased, and when it is off, the learning value is increased the other way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control device for an internal combustion engine, and more particularly to an EGR device for an internal combustion engine equipped with a wandering gas recirculation device (EGR device).

[Conventional technology]

Conventionally, the engine has been controlled by determining control variables such as fuel injection amount and ignition timing based on the engine load (intake air amount or intake pipe pressure) and engine speed, and at the same time reducing NOx emissions. 17 tons of gas recirculation equipment for the purpose of
An internal combustion engine equipped with an EGR device (EGR device) is known. EGR
The device is equipped with a diaphragm type valve body,
The diaphragm chamber and the downstream side of the throttle valve are communicated through a negative pressure passage. In the middle part of the negative pressure passage, there is a
-- A system switching valve (VSV) is interposed, and the opening degree of the VSV is changed to adjust the opening degree of the valve body of the EGR device, thereby controlling the amount of recirculation of exhaust gas.

In this internal combustion engine, the required amount of the engine is different when the EGR device is in operation and when it is not in operation, so the map of the control amount (control amount for operation) when the EGR device is in operation and the map of the control amount when the EGR device is in operation are shown below. The engine is controlled by using and controlling a map with a control amount of 4ffll (non-operating limit: 31 N), and by switching the map.

Tokorochi, EGR device NiT! E G R1tdl i
'nff1 oven control type and EGR valve ref1 amount that changes the EGR control amount of the EGR device,
There is a feedback control type that feeds back the EGR control JB t based on this riff) I.

In the feedback control type, it is possible to prevent fluctuations in the EGR1II control amount due to the influence of atmospheric pressure, etc. in the oven control type, and it is possible to improve drivability and exhaust gas transmission.

The technology related to the above is disclosed in Japanese Patent Application Laid-open No. 58-47.
1.48, JP-A-58-47149, JP-A-61-
There are techniques described in JP-A No. 106961, JP-A-61-106962, and JP-A-61-108857.

[Problem that the invention seeks to solve]

However, the feedback control described above requires a lift sensor to detect the lift amount of the EGR valve. This lift sensor is a so-called analog output type sensor, which is expensive, and also requires an analog/digital (A/D) converter in order to control the output signal of this lift sensor with a microcomputer or the like.

For this reason, the circuits that make up the device become complicated, and there is a problem in that the cost of the system increases significantly compared to the oven control type.

The present invention takes the above facts into consideration and uses a simple circuit to
The objective is to obtain an EGR system for an internal combustion engine that can be well controlled.

[Means for solving problems]

The EGRvi system for an internal combustion engine according to the present invention controls the opening of the EGR valve based on a basic controller for the opening of the EGR valve, which is calculated according to the operating state, and a learning value that is learned when a learning condition is established. An EGR device for an internal combustion engine that controls and recirculates exhaust gas to an intake system, the EGR device includes a valve opening detection switch that detects whether the EGR valve opening is greater than or equal to a predetermined value, and a valve opening detection switch that detects whether the EGR valve opening is greater than or equal to a predetermined value. If the detection switch determines that the EGR valve opening is greater than or equal to a predetermined value, the learning value is decreased, the learning condition is satisfied, and the valve opening detection switch determines that the EGR valve opening is at the end of the predetermined value. and a learned value correction means for increasing the learned value in the case of the present invention.

[Effect]

Therefore 1. When the learning conditions are met, it is possible to correct the error between the learned valve opening request value and the actual valve opening detection value. It is possible to perform highly accurate control by matching the detected value. In addition, when the learning conditions are not met, the EGR valve opening is controlled based on the EGR valve opening basic control amount and the corrected learned value, making it possible to perform stable exhaust gas recirculation control. .

Further, a simple on/off switch can be applied to detect the opening degree of the EGR valve, and the device itself can be made compact.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An internal combustion engine equipped with a control device according to an embodiment of the present invention will be described in detail below with reference to the drawings. Figure 1 shows an outline of this internal combustion engine.
An intake temperature sensor I4 for detecting the intake temperature is installed near 0, and further downstream thereof is a throttle valve 12 whose opening degree is controlled by an accelerator pedal. Also, the throttle valve! A throttle opening sensor 16 for detecting the opening of the throttle valve 12 is attached to the throttle valve 2 .

An air flow meter 13 is arranged between the air cleaner IO and the throttle valve 12.

This air flow meter 13 is connected to the damping chamber 1.
3A, and a measuring plate 13C fixed to the compensation plate 13B, and a potentiometer 13D detects the opening degree of the measuring plate 13C. It has become. The amount of intake air is calculated based on the detected value of the potentiometer 13D.

A surge tank is disposed downstream of the throttle valve 12, and the surge tank communicates with a combustion chamber formed in the engine body via an intake manifold 20. A fuel injection valve 22 is attached to the intake manifold 20 for each cylinder so as to protrude into the intake manifold 20.

A combustion chamber formed in the engine body is communicated via an exhaust manifold 24 to a catalyst device 25 filled with a three-way catalyst. A 0□ sensor 26 is attached to the exhaust manifold 24 for detecting the residual oxygen concentration in the exhaust gas and outputting a signal that is inverted around the stoichiometric air-fuel ratio. Further, a water temperature sensor 28 is attached to the engine block of the engine body so as to penetrate the engine block and protrude into the water jacket to detect the engine cooling water temperature.

An exhaust gas circulation path 30 is arranged to communicate between the exhaust manifold 24 and the upstream side of the surge tank 18.
An EGR pulp 36 including a diaphragm 32 and a valve body 34 is attached. The diaphragm chamber 38 of the EGrl valve 36 is connected to a vacuum switching valve (V
It communicates with an EGR port 44 bored downstream of the throttle valve 12 through a negative month passage 42 in which a 5V) 40 is disposed. In this embodiment, when the intake pipe pressure is sufficient to apply to the EGR valve body 34, the VSV40
The pressure in the diaphragm chamber 38 is changed by controlling the duty ratio of the electric power supplied to
can be adjusted. The valve body 34 has a predetermined lift i or more and a predetermined lift i! An on/off type valve opening detection switch 45 whose output is reversed when + is installed is installed. This predetermined lift leaf corresponds to the valve opening of 34, which is the optimum valve body in the steady operating state obtained from the engine speed, intake air amount, intake temperature, vehicle speed, etc., and the valve opening is detected at this point. The switch 45 is turned on.

A spark plug 46 is attached to each cylinder so as to protrude into the combustion chamber through the cylinder nut of engine zero 4, and this spark plug 46 is connected to a control circuit 52 via a distributor 48 and an igniter 50. .

A rotation angle sensor 54 is installed within the distributor 48 and is comprised of a signal rotor fixed to the distributor shaft and a pickup fixed to the distributor housing. The rotation angle sensor 54 outputs to the control circuit 52 an engine rotation speed signal consisting of a pulse train generated every 30@CA, for example.

The control circuit 52 includes a microcomputer. That is, the control circuit 52, as shown in FIG.
8, MPU60, input/output capotro 2, input portro 4,
It is configured to include output ports 6, 68, and 70 and buses 72 such as data buses and control buses that connect them. An analog-digital (A/D) converter 74 and a multiplexer 76 are connected to the input/output capotro 2. The multiplexer 76 is connected to a potentiometer 13D1 via a buffer 75, a vehicle speed sensor 79 via a buffer 77, a water temperature sensor 28 via a buffer 78, and a throttle opening sensor 1 via a buffer 80, respectively.
The intake air temperature sensor 14 is connected to the intake air temperature sensor 14 via the air filter 6 and the buffer 82 .

The MPU 60 controls the A/D converter 74 and the multiplexer 76 via the input/output capotro 2, and controls the water temperature sensor 28.
The output, the intake air temperature sensor 14 output, and the throttle opening sensor 16 output are sequentially A/D converted and stored in the RAM 56.

The input port 4 has a comparator 84 and a buffer 86.
The 02 sensor 26 is connected through the buffer 87, and the valve opening detection switch 45 is connected through the buffer 87. Also,
A rotation angle sensor 54 is connected to the input port 4 via a waveform shaping circuit 8.

Further, the output port 6 is connected to the vacuum switching pulp 40 via the drive circuit 90, and the output port 8 is connected to the vacuum switching pulp 40 via the drive circuit 90.
is connected to the igniter 50 via a drive circuit 92, and the output port door 0 is connected to the fuel injection valve 22 via a drive circuit 94 including a down counter. Note that 96 is a clock and 98 is a timer. The ROM 58 stores in advance a control routine program to be described below, a basic ignition timing map and a basic fuel injection time map (basic fuel jn amount map) depending on whether the EGR device is activated or deactivated.

The basic fuel injection amount is calculated based on the output values of the potentiometer 130, the rotation angle sensor 54 (engine speed), and the intake air temperature sensor 14.0. The correction is made sequentially based on the output values of the sensor 26 and the water temperature sensor 28.

Further, the basic ignition timing is calculated based on the output value of the potentiometer 13D1 rotation angle sensor 54, similarly to the calculation of the basic injection amount, and its correction is sequentially performed based on the output value of the water temperature sensor 28.

Furthermore, the EGR valve basic control amount, that is, the duty ratio of the electric power supplied to the VSV 40 is determined based on the potentiometer 13D and the rotation angle sensor 54, and in this embodiment, the value is corrected by the valve opening detection switch 45. It looks like this.

The operation of this embodiment will be explained below with reference to the flowchart of FIG. Note that the basic ignition timing calculation routine, basic fuel injection time (γ routine), and these execution routines are the same as the control of a conventional electronically controlled single-type internal combustion engine, so they will be omitted, and the EGR control amount correction routine, which is a feature of the present invention, will be omitted. I will only explain about.

First, in step 100, it is determined whether the conditions for operating the EGR device are satisfied based on the engine cooling water temperature, etc., and if the conditions are not satisfied, the process moves to step 102 and the EGR basic control amount DEGR is set to 0. , this routine ends. If the conditions are met in step 100, the process moves to step 104 and engine conditions are read. That is, the engine speed is calculated from the signal from the rotation angle sensor 54, the intake air amount is calculated from the button yometer +3D, and the intake air temperature sensor 14 and the vehicle speed sensor 7
9 to detect the intake temperature and vehicle speed, respectively.

In the next step 106, the EGR base zero control amount DTEGR is read from a map stored in the ROM 58 in advance based on the parameters obtained in step 104, and the process moves to step 10B.

This routine from step 10 to step 112 is a routine for detecting the steady driving state of the vehicle, and the setting of the learned value of the EGR control amount is limited to certain conditions.

First, in step 108, the vehicle speed is set to a predetermined value (A±αkm/
It is determined whether or not it is within the range of h), and only in the case of an affirmative determination, the process moves to step IIO, which is determination of the next condition. In step 110, the amount of intake air is set to a predetermined value (B±βm″
), and only in the case of an affirmative determination, the process moves to step 112, which is determination of the next condition. In step 112, the engine speed is set to a predetermined value (C±γr, p
, m), and if the determination is affirmative, the process moves to step 114. Note that the above three predetermined ranges are ranges in which conditions are substantially the same as those in the experimental stage of the internal combustion engine applied to this embodiment. Here, if a negative determination is made in steps 108, 110, or 112, it is determined that the vehicle is not in a steady driving state, and the process moves to step 116, where the EGR control execution value DEGR is set to the EGR control execution value DEGR read in step 106. For [J T
The previous learning value ELEGR is applied to fEGR by 11n (default).

In step 114, it is determined whether or not the valve opening degree detection switch 45 is on, and if it is determined that it is on, it is determined that the lift l of the valve body 34 is greater than or equal to a predetermined amount;
The process moves to step 118, and the previous state of the valve opening detection sensor is determined. In this step 118, if it is determined that the valve opening detection switch 15 is continuously turned on, it is possible to check that the valve body 34 is opened to the required opening or more. l=: It is determined that the G R control amount is too large, and the value obtained by subtracting the constant value DLEGR from the learned value E L I) and G R is set as a new learned value range LEGR.
As a result, the process moves to step 116.

If the determination in step 118 is negative, that is, the contact point of the valve opening detection switch 45 has just been switched,
It can be checked that the valve body 34 is not opened more than the required opening degree,
Since the previous learned value ELEGR is applied as it is as the current learned value ELECR, step 12
2 and proceeds to step 116.

If it is determined in step 114 that the valve opening detection switch 45 is off, it is determined that the EGR system (NU amount) is insufficient, and the process proceeds to step 120.
The value obtained by adding the constant value DLEGR to the learned value ELEGR is set as a new learned value ELEGR, and the process moves to step 116.

In this way, the learned value is changed only by the on/off state of the valve opening detection switch 45, and the EGR control execution value DEGR is corrected, so the number of parts in the device is small, and the device itself can be made compact. Significant cost reductions can be achieved. Also, the previous ON/OFF state of the valve opening detection switch 45 is
Since the correction value of the EGR control amount is determined both in the off state and in the current on/off state, it is possible to obtain accuracy in the case of correction using a lift sensor or the like having a complicated structure, and in road distance, etc.

In this embodiment, an internal combustion engine that calculates the fuel injection time based on the intake air amount and the engine rotational speed has been described. It can also be adapted to Also,
Although an example in which the basic ignition advance angle and the basic fuel injection time are used as the basic control amount has been described above, either the basic ignition advance angle or the basic fuel injection time may be used as the basic control amount.

〔Effect of the invention〕

As explained above, the EGR device for an internal combustion engine according to the present invention has the excellent effect of being able to perform accurate control with a simple circuit.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of the internal combustion engine applied to this embodiment;
The figure is a block diagram showing details of the control device shown in FIG. 1, and FIG. 3 is a control flowchart. 36... EGR valve, 45... Valve opening detection switch, 52... Control circuit.

Claims (1)

[Claims] (1) The opening of the EGR valve is controlled based on the basic control amount of the EGR valve opening calculated according to the operating state and the learning value learned when learning conditions are met, and exhaust gas is returned to the intake system. The EGR device for an internal combustion engine that circulates the EGR includes a valve opening detection switch that detects whether the EGR valve opening is equal to or greater than a predetermined value, and a valve opening detection switch that detects the EGR valve opening when a learning condition is satisfied. is determined to be greater than or equal to a predetermined value, the learned value is decreased, and when the learning condition is satisfied and the EGR valve opening is determined to be at the end of the predetermined value by the valve opening detection switch, the learned value is increased. An EGR device for an internal combustion engine, comprising: a correction means.