JPH04128545A - Exhaust gas circulation control device of internal combustion engine - Google Patents

Abstract

PURPOSE:To smoothly carry out abnormality judgement of a circulation device without deteriorating drivability by controlling a controlled variable of an internal combustion engine so as not to cause output change of the internal combustion engine when a circulation pipe opening-closing means moves from closing to opening and by diagnosing an abnormal motion of the circulation device by a drive condition. CONSTITUTION:During the time of driving an engine, a control correction signal not to change a driving state (for example, the number of rotation of the engine) is output simultaneously when an opening-closing signal is output to an opening-closing means 13 provided on a circulation pipe 12 connecting an exhaust pipe and an air suction pipe to each other in a control means 14. Additionally, respective driving states at the time of EGR valve closing motion and opening motion are detected by an engine condition detection means 15, memorized in a memory means 16, judged by a judgement means 17 whether a rate of change of the driving state is more than a specific amount or not and in the case when it is more than the specific amount, an abnormal state is memorized simultaneously when an alarm lamp is put on by an alarm means 18. Consequently, it is possible to certainly diagnose abnormality of EGR flow rate without accompanying variation of an engine output and uncomfortable lowering of drivability.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is directed to so-called exhaust gas recirculation of internal combustion engines, which controls exhaust gas recirculation (EGR) in which exhaust gas from internal combustion engines such as automobiles is recirculated to the intake side. (EGR) control equipment, especially for internal combustion engines equipped with self-diagnosis functions.
G R) Regarding the control device.

[Conventional technology]

Exhaust gas recirculation (E GR) is widely practiced.

By the way, 2 In recent years, the demand for exhaust gas purification has been increasing, and for this purpose it is necessary to diagnose the EGR device. It has been proposed to determine whether or not this EGR device is abnormal based on changes in the operating conditions 111 (for example, intake pipe pressure, air-fuel ratio, etc.) of the internal combustion engine during opening and closing operations.

[Problem to be solved by the invention]

However, the EGR of the internal combustion engine which is the above-mentioned prior art
The device opens and closes the EGR valve for diagnostic purposes, but no consideration is given to the effect on the internal combustion engine during this valve opening/closing operation and the associated negative impact on the drivability of the vehicle. However, there was a problem in that drivability was affected by the shock caused by the vehicle.

Therefore, in view of the above-mentioned problems in the prior art, the present invention provides an internal combustion engine equipped with an EGR amount self-diagnosis ability that does not inhibit the operation of the internal combustion engine or deteriorate the drivability of the vehicle even during EGR abnormality diagnosis operation. The purpose is to provide an exhaust gas recirculation control device.

[Means for Solving the Problems] According to the present invention, the above-mentioned object is achieved by: 31 provided between the exhaust pipe and the intake pipe of an internal combustion engine for recirculating at least a portion of exhaust gas to intake air; ! a flow pipe, a reflux pipe opening/closing means for opening and closing the reflux pipe, an operating state detecting means for detecting the operating state of the internal combustion engine, and a reflux pipe opening/closing means for detecting the operating state of the internal combustion engine based on a detection signal from the operating state detecting means. comprising a control means for controlling the opening/closing operation, and further an alarm means,
The control means further includes a storage means for storing the values of the detection signals outputted from the operating state detection means when the reflux pipe opening and closing means is operating to open and close, respectively. When the return pipe opening/closing means shifts from its closing operation to its opening operation, the control amount is corrected so as not to change the operating state of the internal combustion engine, and the opening/closing of the return pipe opening/closing means stored in the storage means is performed. The internal combustion apparatus is characterized in that it is determined whether or not the recirculation device is abnormal by comparing detection signal values during operation, and when the recirculation device is determined to be abnormal as a result of the above judgment, the above alarm means is activated to issue an alarm. This will be achieved by the engine's gas reflux control system.

[Effect]

According to the above exhaust gas recirculation control device for an internal combustion engine according to the present invention, when the recirculation pipe opening/closing means shifts from the closed state to the open state, the output of the internal combustion engine generally decreases; In order to prevent such changes in output, the system suppresses fluctuations in engine output by controlling so-called control variables of the internal combustion engine, such as the intake air amount or ignition timing, and at the same time, controls the operating state of the internal combustion engine stored in the storage means. Since the abnormal operation of the recirculation device is diagnosed based on the signal displayed, it is possible to smoothly determine the abnormality of the recirculation device without deteriorating drivability due to fluctuations in engine output.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. Throttle opening THV detected by throttle sensor 2, water temperature sensor 19 rotation sensor 7, and air flow sensor 8 provided in engine 10.

The engine cooling water temperature TW, engine speed N, and intake air amount Qa are input to the control unit 9, and the engine 1
Fuel injection pulse intensity Ti (fuel supply amount) required for 0,
Ignition pulse θi, ISCSC bypass amount control signal Di, and EGR valve opening/closing signal are transmitted to injector 6, ignition coil 19°ISC valve 3. They are output to the EGR solenoid valves 5, respectively. FIG. 2 is a block diagram showing the configuration of the present invention. The control means 14 is an opening/closing means 13 (E
G R solenoid valve5. At the same time as outputting an opening/closing signal to the EGR valve 4), a correction signal for control for not changing the operating condition M (for example, engine speed) is outputted. As this correction signal, the ISC bypass air amount import 9
Either one or a combination of advancing the ignition timing and increasing the fuel injection pulse width can be adopted. The respective operating states when the EGR valve is closed and opened are detected by the engine state detection means in block 15 and stored in storage means 16 . The judgment means 17 judges whether the change in the operating state is more than a predetermined value, and if it is more than the predetermined value, the alarm means 8 turns on the warning lamp and at the same time stores the abnormal state. FIG. 3 is an explanatory diagram of the operation of the present invention. The EGR valve is changed from closed operation to open operation and at the same time the ISC bypass air amount is increased by 80. ΔQ is a correction for the decrease in engine output due to exhaust gas flowing into the intake pipe, so if an appropriate EGR flow rate is flowing in, there will be no decrease in output as a whole, and the output will not decrease as shown in b and e. No increase or decrease in engine speed N occurs. In the case of an increase as shown in b, the EGR flow rate is too small, so the engine output does not decrease due to the EGR flow rate, and the increase occurs by 60 minutes. In the case of descending as shown in C, the EGR flow rate is excessive and the engine output decreases significantly due to the EGR flow rate, so the EGR flow rate descends to 2 even though it has been corrected by 60 minutes. Figure 4 shows that when the EGR valve is shifted from closed operation to open operation, the ignition timing is advanced by Δθi instead of the increase in ISC bypass air amount ΔQ.
This is to compensate for the decrease in engine output due to EGR flow rate. In addition to the above, the injection pulse width T1 may be increased by ΔTi in order to compensate for a decrease in engine output or engine speed due to the EGR flow rate. FIG. 5 shows a flowchart of the control program of the present invention. Step 20
The throttle opening degree THV is set to a predetermined value THV.

Check if it is more closed, if YES, step 21
Check whether the engine speed N is lower than the predetermined value NO. These determinations are made to perform EGR diagnosis within a region where a change in the engine condition due to the EGR flow rate, that is, a decrease in engine output occurs. In steps 22 and 23, it is checked whether the engine rotational speed change ΔN and throttle opening change ΔTHV within a predetermined time Δ are smaller than predetermined values α and β, and if they are, it is determined that the operation is steady, and step 24
Proceed to. In step 24, measure the engine speed No'e when the EGR valve is fully closed, and in step 25, open the EGR valve.
Also, the engine rotation speed N1 when the ISC and the bypass air amount ΔQ increase is measured.

Instead of increasing the ISCSC bypass amount ΔQ, the ignition timing may be advanced by Δθi, or the injection pulse width may be increased by ΔT.
i may be increased. E in step 26 and step 27
Engine speed change sound when the GR valve is fully closed and opened (NI
NO), (No N1) is the predetermined value ΔNp and Δ
Check whether it is within NM, and if it does not exceed NM, it is determined that the EGR flow rate is normal, and in step 28, the alarm lamp is turned off and the EGR
R: Store 10K in RAM. N 1- No
> If ΔNp, the warning lamp lights up + - EGR is too low.
Store in AM. If No-N5>ΔNM, a warning lamp is turned on and the excessive amount of EGR is stored in the RAM.

〔Effect of the invention〕

As is clear from the above detailed explanation, the exhaust gas recirculation control device for an internal combustion engine according to the present invention can reliably detect abnormalities in EGR flow rate without fluctuations in engine output or unpleasant deterioration in drivability. This results in the excellent effect of making it possible to diagnose.

[Brief explanation of drawings]

FIG. 1 is a system diagram of the present invention, FIG. 2 is a block diagram of the present invention, FIGS. 3 and 4 are operation explanatory diagrams of the present invention, and FIG. 5 is a flowchart of the control program of the present invention. . 3. ISC valve, 4...EGR valve, 5...E
GR solenoid valve, 6...injector, 7...
・Rotation sensor ・9" control unit, 19...

Claims (1)

[Claims] 1. A recirculation pipe provided between an exhaust pipe and an intake pipe of an internal combustion engine for recirculating at least a portion of exhaust gas to intake air; a recirculation pipe opening/closing means for opening and closing the recirculation pipe; Operating state detection means for detecting the operating state;
A control means for controlling the opening/closing operation of the reflux pipe opening/closing means based on a detection signal from the operating state detecting means, and further includes an alarm means, the control means further comprising an opening/closing operation of the reflux pipe opening/closing means. and storage means for storing the values of the detection signals output from the operation state detection means when the operation state detection means is in the closing operation, so that when the return pipe opening/closing means transitions from its closing operation to its opening operation, The control amount is corrected so as not to change the operating state of the engine, and the detection signal value during the opening/closing operation of the reflux pipe opening/closing means stored in the storage means is compared to determine whether or not the reflux device is abnormal. An exhaust gas recirculation control device for an internal combustion engine, characterized in that the exhaust gas recirculation control device for an internal combustion engine is characterized in that the above-mentioned alarm means is activated to issue an alarm when it is determined that there is an abnormality as a result of the above-mentioned judgment.