JPS6251747A - Exhaust gas recirculation control device - Google Patents

Abstract

PURPOSE:To aim at simplifying the structure of a self-diagnosing device, by comparing a detected value of an intake-air volume, upon turning on of an EGR with a detected value of the same upon turning off of an EGR so that an EGR is self-diagnosed with no flow-meter sensor etc. being disposed in an exhaust gas recirculation pipe. CONSTITUTION:During operation of an internal combustion engine A, a control means E judges whether a shut-off means D in an exhaust recirculation pipe C is in the opening operation range or not with the use of a map in accordance with parameters such as, for example, an engine rotational speed, an intake-air volume, etc. in order to check whether the EGR is in its actuating range or not, and also judges whether the internal combustion engine A is in its steady state operating condition or not. When it is judged that the shut-off means is in the opening operation range and the engine is in the steady state operating condition, detections values from an intake-air volume detecting means F as the shut-off means D is opened or closed, are stored in a memory means G. Further, the thus stored detection values are compared with each other by means of judging means H. If it is judged that the difference between both values is below a predetermined value, an alarm means I is actuated to inform the drivers concerning the abnormal condition in the EGR.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an exhaust gas recirculation control device for recirculating part of the exhaust gas of an internal combustion engine to the intake pipe of the internal combustion engine. The present invention relates to a self-diagnosis device for a control device.

[Prior Art] Conventionally, this type of exhaust gas recirculation control device (hereinafter referred to as EGR) has been widely used in internal combustion engines as a means to reduce nitrogen oxides (NOX) in exhaust gas (Japanese Patent Application Laid-Open No. Publication No. 59-192831 By the way, when a failure occurs in the EGR due to malfunction of the EGR valve or blockage of the EGR piping, NOx tends to increase significantly.However,
EGR failure has little effect on driving performance itself, so
A large amount of NOx may be emitted without the driver noticing that something is wrong, polluting the atmosphere.

As a means to solve this problem, for example, JP-A-56-6
As described in 0912@publication, the detection value from the sensor is corrected by learning control etc. according to a predetermined setting pattern, and an abnormality is reported when the correction value exceeds a predetermined value. It is being

[Problems to be Solved by the Invention] However, in order to apply the above-mentioned conventional technology to EGR, it is necessary to install a flow sensor, for example, in the EGR pipe, to detect the operating state of EGR, which makes the configuration complicated. Identify problems.

[Means for Solving the Problems] The present invention, which has been made to achieve the above problems, includes a recirculation pipe C that recirculates exhaust gas from an internal combustion engine A to an intake pipe B, as shown in FIG.
, an opening/closing means for opening and closing this recirculation pipe C, a control means E for controlling the opening and closing of this opening/closing means, an intake air amount detection means F for detecting the amount of intake air into the intake pipe B, and the above-mentioned control means E. When the opening/closing means is performing an opening operation and a closing operation, a storage means G separately stores the detected values from the detection means F, and based on the values of both sides output from this storage means G, both sides are detected. It comprises a determining means H for determining whether the difference between the output values is within a predetermined range, and an alarm means I for issuing an alarm when the determining means determines that the difference is within the predetermined range. That's what happens.

Here, the storage means G includes not only a digital memory but also an analog type storage means using a capacitor or the like.

The above-mentioned warning means (2) is a means for notifying the driver of an EGR abnormality, and includes a text display, an audible warning, etc. in addition to a lamp display.

[Operation] First, the control means E determines whether or not the opening/closing means is in the opening operation range based on the EGR operation range, that is, a map predetermined based on parameters such as the engine speed and intake air amount of the internal combustion engine A. A judgment is made. Roughly speaking, it is determined whether or not the internal combustion engine A is in a steady operating state, and when the above-mentioned operating range and steady operating state conditions are satisfied, the following processing is performed. In other words, with the opening operation of the opening/closing means,
That is, the detected value from the intake air amount detection means F is stored in the storage means G in the EGR operating state. On the other hand, the opening/closing means is operated to close, and the detection value from the detection means F at that time is stored in the storage means G. Then, the determination means H compares both side output values stored in the storage means G, and when it is determined that the difference is less than a predetermined value, the alarm means I is activated to notify the driver of the EGR abnormality.

In other words, when EGR is normal, EGR is ON and OFF.
In this case, the amount of intake air fluctuates by more than a predetermined value. Therefore, if there is no fluctuation greater than the expected predetermined value, E
It is determined that there is an abnormality in the GR and a warning is given to the driver.

[Embodiment] FIG. 2 shows a schematic configuration diagram of an internal combustion engine and its control system to which an embodiment of the present invention is applied.

1 is a cylinder of a six-cylinder internal combustion engine, and 2 is an air flow sensor that detects the amount of intake air in an intake pipe 3a.

4 is an electromagnetically actuated fuel injection valve provided near each cylinder intake port of the intake manifold 3, and 6 is a distributor. The rotor of this Dist 1 Novuator 6 is driven to rotate at 1/2 of the engine rotation speed, and a rotation sensor 7 that outputs a signal indicating the engine rotation speed, fuel injection timing, and a cylinder discrimination signal is disposed inside. . 9 is a throttle valve, 10 is a throttle position sensor that detects the opening degree of throttle valve 9, 11 is a thermistor-type water temperature sensor that detects the engine cooling water temperature, and 12 is an intake air temperature sensor that detects the intake air temperature. . 13 is a vacuum servo type exhaust gas recirculation control valve (hereinafter abbreviated as EGR valve) installed in the exhaust gas circulation path 17 connected between the intake manifold 3 and the exhaust manifold 16, and controls the EGR valve 13. The control line 18 connects the diaphragm chamber of the EGR valve 13 and the surge tank 19.
A modulator 14 that determines the opening degree of the EGR valve 13 and a solenoid valve 15 that switches whether or not to perform exhaust gas recirculation are connected to the control pipe 18.
will be installed in The solenoid valve 15 is an output port of the electronic control circuit 8.
1-107 (Fig. 3), and operates so that atmospheric pressure is passed to the modulator 14 when it is cold, idling, or under high load. On the other hand, when exhaust gas recirculation is performed, the throttle of the surge tank 19 is operated. An actuation signal is received to apply negative pressure near the valve 9 to the modulator 14 . 3
0 is a warning lamp that warns of EGR abnormality.

FIG. 3 shows a block diagram of an electronic control circuit 8 that controls the fuel injection amount of the internal combustion engine to control the air-fuel ratio, various sensors, etc. The electronic control circuit 8 is mainly composed of a microcomputer.

The control circuit 8 includes an air flow sensor 2, a rotation sensor 7, a throttle position sensor 10. Each detection signal from the water temperature sensor 11 and the intake temperature sensor 12 is taken in, the fuel injection interval is calculated based on these detection data, and the opening time of the fuel injection valve 4 is controlled to perform air-fuel ratio control. 100 is an MPU (microprocessor unit) that executes arithmetic processing according to a predetermined program, 101 is an interrupt control unit that outputs an interrupt signal to the MPU 100, and 102 is a unit that counts the rotation angle signal from the rotation sensor 7 and calculates the engine rotation speed. A counter section 104 is an A/D converter that selectively inputs detection signals (analog signals) from the intake pipe pressure sensor 2, water temperature sensor 11, and intake temperature sensor 12 and converts them into digital signals. 105 is a ROM which is a read-only memory in which map data used for programs and calculations is stored in advance, and 106 is a RAM which is a readable and writable non-volatile memory and retains its stored contents even after the key switch is turned off. 107 is an output boat connected to the electromagnetic valve 15; 108 is an output counter section including a register for outputting a fuel injection amount (time) control signal;
Input the fuel injection amount data sent from MPU 100,
Based on this data, the duty ratio of the control pulse signal that controls the opening time of the fuel injection valve 4 is determined, and an injection amount control signal is output. Note that the control signal output from the output counter section 108 is applied to the fuel injection valve 4 of each cylinder via the power amplifier 110. In addition, the control circuit 8
Inside, MPU 100, interrupt control section 101, input counter section 102, A/D converter 104, ROM 10
5, RAM l06 and output counter unit 108 are each connected to common bus 111, and transfer of necessary data is performed by MP
This is done by a command from U100.

Next, the operation will be explained.

When the internal combustion engine starts, the EGR operation map stored in the ROM 105 in the control circuit 8, that is, the map whose parameters are the intake air amount and the engine speed (not shown).
Based on this, the MPU 100 determines whether or not it is in the EGR operation range based on the detected values of the current intake air and engine speed. When it is determined that it is in the operating region, the solenoid valve 15 is energized to apply negative pressure near the throttle valve 9 of the surge tank 19 to the modulator 14, and the EGR valve 13 is activated.
By opening the valve, exhaust gas is recirculated to the intake manifold 3.

The self-diagnosis of EG'R, which performs this kind of operation, is
This is executed as an interrupt process in the flowchart shown in the figure. The interrupt condition is set, for example, only once after 30 minutes have passed since the engine was started. This is to reduce the number of EGR operation interruptions due to frequent self-diagnosis.

In the flowchart of FIG. 4, first, step 20
At step 205.0, it is determined whether or not the EGR is in the operating range.If it is determined that the EGR is in the operating range, the next step 205.
The process then proceeds to step 210. These steps 205
．． In 2'IO, the deviation ΔNE of the engine speed NE per predetermined time and the deviation ΔTA of the throttle opening TA per predetermined time are determined. Next, in step 215, the engine speed deviation ΔNE and the throttle opening deviation ΔTA are equal to or less than predetermined values α and β (ΔNE≦
A determination is made as to whether α, ΔTA≦β). this is,
This is to prevent if subsequent processing is executed when the engine is not in a steady operating state, that is, during startup, acceleration, or deceleration, it may be mistaken for a detected value in these states. In this step 215, both rYEsJ
In this case, that is, when it is determined that the operating state is steady, the process proceeds to step 220, where the intake air amount is detected by the air flow meter 2 when EGR is ON, and this is stored in the RAM 106.
to be memorized. At this time, in order to prevent erroneous recognition of sudden changes in intake air amount, the average of the detected values QON for about 3 seconds is determined. Next, step 225 is executed to energize the solenoid valve 15, close the EGR valve 13, and stop the recirculation of exhaust gas. Then, in step 230, E
The intake air amount is detected by the air 70 meter 2 when the GR is OFF, and this is stored in the RAM 106.

In this case, as in step 220 above, the average of the detected values Q OFF for about 3 seconds is used.

In the next step 235, the above step 220.2
The intake air amount difference ΔQ between the intake air amounts QON and Q OFF obtained in step 30 is calculated, and in the next step 240, ΔQ≧
Determine T. Here, T is a value selected according to the detected value QON. If ΔQ is equal to or greater than the predetermined value 1, it is determined that the EGR is normal, and the process proceeds to step 245, where the EGR is restarted. On the other hand, if 8Q is less than the predetermined value γ, it is determined that the EGR is abnormal, and the process proceeds to step 250, where the warning lamp 30 is turned on and the abnormality information is stored in the RAM for self-diagnosis. A warning from the above warning lamp 30 alerts the driver to E.
It is possible to notify 1 of an abnormality in the GR and take measures to repair the failure.

In other words, when EGR is ON and OFF, there should be a difference of more than a predetermined value in the amount of intake air by the amount of recirculated gas that is returned to the intake manifold 3. If there is no difference, it is determined that there is an abnormality and the operation is stopped. This will be communicated to the public.

Next, another embodiment will be described according to the flowchart of FIG. In the flowchart in Figure 5,
Regarding the determination of whether the vehicle is in a steady operating state, the intake air f
This is done by detecting f1QON and QOFF a predetermined number of times and using the deviation.

That is, after determining the EGR operating region in step 300, in steps 305 to 315, EGR is turned on and off.
The intake air amounts QON and QOFF during FF are detected, respectively, and these processes are repeated a predetermined number of times based on the determination in step 320. Then, when the process is repeated a predetermined number of times, in step 325, the intake air filQON1...
Calculate the average value and deviation of QONn.

Next, it is determined whether the calculated deviation is within a predetermined value (step 330), and if it is within the predetermined value, the process proceeds to the next step 333. That is, in step 333,
If it is determined that the value is within the predetermined value, the intake air ff1QO
Since this indicates that the variation in N is small, it is determined that the steady operating state is present, and the process proceeds to step 333.

In step 333, when the FGR is OFF,
The average value QOFF of FFI・Q0FFn is calculated, and then in step 335, the average value PO of the intake air amount is calculated.
N, intake air amount fluctuation at POFF〇 (=QON
-QOFF> is calculated. Regarding this intake air amount difference ΔQ, determination of ΔP≧γ (γ: positive number) is executed in step 340, and if rYEsJ, it is determined that EGR is normal (step 345), and EGR is turned on to restore EGR. On the other hand, in the case of "No", the warning lamp 30 is turned on to notify the driver of the EGR abnormality, and the information is stored in the RAM (step 35'O).

[Effects of the Invention] As explained above, according to the present invention, EGR self-diagnosis can be performed by comparing the detected value of the intake air amount when EGR is ON and OFF. Since there is no need to provide a flow rate sensor or the like in the reflux pipe unlike in the conventional technology, the configuration can be simplified.

In addition, clogging of the reflux tube is also indicated by a decrease in the difference in detected values, so abnormalities can be easily detected in this case as well.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is a schematic configuration diagram showing an embodiment of the present invention, FIG. 3 is a block diagram of the embodiment, and FIG. 4 is a flowchart of the embodiment. FIG. 5 is a flowchart of another embodiment. A... Internal combustion engine B... Intake pipe C... Reflux pipe D... Opening/closing means E... Control means
F...Intake air amount detection means G...Storage means
H... Judgment means ■... Alarm means

Claims (1)

[Scope of Claims] A recirculation pipe that recirculates exhaust gas from an internal combustion engine to an intake pipe, an opening/closing means for opening and closing this recirculation pipe, a control means for controlling opening/closing of this opening/closing means, and a control means for controlling the amount of intake air into the intake pipe. an intake air amount detection means for detecting; a storage means for separately storing the detection values from the detection means when the opening/closing means is opened and closed by the control means; determining means for receiving the detected value and determining whether the difference between the two detected values is within a predetermined range; and an alarm means for issuing an alarm when the determining means determines that the difference is within the predetermined range. An exhaust gas recirculation control device comprising: