JPS63201355A - Trouble diagnosing device for exhaust gas recirculating device - Google Patents

Abstract

PURPOSE:To enable accurate diagnosis of a trouble by a method wherein a cause-effect relation between an engine state and the opening of a throttle valve during normal working of EGR function is stored, and by monitoring the actual opening of the throttle valve based on the opening of the throttle valve during normal working of EGR function, the system trouble of an EGR device is diagnosed. CONSTITUTION:This device includes an engine speed sensor 4 and an engine load sensor 5, detecting the rotation speed and the load, respectively, of an internal combustion engine, and a throttle valve opening sensor 7, signals therefrom being inputted to a control device 11. In the control device 11, from the rotation speed and the load of the internal combustion engine, a throttle valve opening map predetermined according to a demand for engine performance is retrieved by a retrieving means 11A to determine the opening date of the throttle valve. The opening data of the throttle valve is outputted to a discriminating means 11B, and is compared with actual opening data from an opening sensor 7. When a deviation therebetween exceeds a given value, function of the EGR device is discriminated to be abnormal to drive an alarming means 13, on which a trouble is displayed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is a failure diagnosis method for an EGR device for monitoring and diagnosing the quality of the operating function of an exhaust gas recirculation device (hereinafter referred to as an EGR device) for an internal combustion engine. Regarding equipment.

[Conventional technology]

As a conventional method for diagnosing the operating state of an EGR device mounted on a vehicle, there is a method of measuring the NOx concentration in exhaust gas at a service station at a dealer or the like. However, this method requires an exhaust gas analysis device, and is not a method that can easily diagnose the function of the EGR device. As another method, for example, EG
Some devices are equipped with means for detecting movement of the valve body of the EGR valve of the R device. However, although this method can detect a failure in the rond part connected to the valve body of the EGR valve body,
It is not possible to detect a systematic abnormality in the operating function of the EGR device.

[Problem that the invention seeks to solve]

The above conventional technology is a simple diagnostic method that can detect failures in the rod section connected to the valve body of the EGR valve body, but it is possible to detect failures in the rod section connected to the valve body of the EGR valve body.
There was a problem in that no consideration was given to detecting the operating function of the R device, and it was not possible to perform systematic abnormality detection of the EGR function.

□The purpose of the present invention is to solve the problems of the prior art described above,
An object of the present invention is to provide a failure diagnosis device for an EGR device that can accurately diagnose a failure in a system function of an EGR device while mounted on a vehicle.

(Means for Solving the Problem) The above objective is to determine the cause and effect between the opening of the air flow throttle valve installed in the intake passage and the engine air-fuel ratio fluctuation, which is determined by the engine state of the engine speed and engine load. This is achieved by a failure diagnosis device for an EGR device that determines an abnormality in the EGR device by monitoring the relationship.

[Effect]

The opening degree of the throttle valve that controls the intake air amount for the engine has a predetermined correspondence relationship based on the desired air-fuel ratio determined by the rotational speed and load condition of the engine, and this predetermined correspondence relationship is This is based on the EGR rate (the intake air amount is the ratio of the exhaust gas recirculation amount) that is set to limit gas NOx, and if an abnormality occurs in the EGR device, the throttle valve opening will be changed. Based on the fact that the inventors' experiments have revealed that differences appear as differences, failures in the EGR system can be diagnosed based on the difference between the predetermined correspondence between the throttle valve opening and the engine state and the actual correspondence. .

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

FIG. 1 is a block diagram showing one embodiment of a failure diagnosis device for an EGR device according to the present invention. In Fig. 1, 4 is an engine speed sensor that detects the rotational speed of the engine, 5 is an engine load sensor that detects the engine load, and 7 is a throttle valve opening sensor that detects the opening of a throttle valve for controlling air flow rate. It is. 11 is a control device, 11A is a throttle valve opening degree search means for searching the throttle valve opening degree under normal conditions, 11B is a failure determination means, 12 is an engine temperature sensor, and 13 is an alarm means.

FIG. 2 is an explanatory diagram of the throttle valve opening degree map of the search means 11A of FIG. 1. This map is a three-dimensional map representing the throttle valve opening degree θTll0 based on the engine speed N and engine load, and is stored in advance as base data in which the above three engine elements are related in a matrix when the EGR function is normal. Note that if the engine speed N and engine load are assigned only to the EGR region of the engine, the capacity of memory etc. will be advantageous, and each division point and number of grids will be
It can be set arbitrarily depending on the area.

FIG. 1 shows the speed signal N of the engine speed sensor 4 and the load signal N of the engine load sensor 5, respectively, by the search means 1 of the control device 11.
It is input to 1A. The search means 11A uses the input speed N
The throttle valve opening data θT is obtained by searching the throttle valve opening map predetermined according to the engine performance requirements shown in Figure 2 based on the load and load.
It outputs ll0 to the determining means 11B. The actual throttle valve opening signal θTl (of one throttle valve opening sensor 7) is also input to the determining means 11B.

The next determination means 11B is the data θTHO obtained from the map.
and actual data 0TI4, and when the deviation between these two data is greater than a predetermined value, it is determined that the function of the EGR device is abnormal, and the output signal AL is output to the alarm means 13 to prevent the EGR device from operating. Displays the details of the failure. Further, the output signal AL from the determination means 1.1B is limited by the temperature signal of the temperature sensor 12 of the engine, and for example, when the temperature is below a predetermined temperature, the occurrence of N Q The alarm means 13 is prevented from being activated even when the value is greater than a predetermined value.

FIG. 3 is an explanatory diagram of the abnormality determining operation of the determining means 11B of FIG. 1. This explanatory diagram is partially extracted from the throttle valve opening map in Figure 2, and shows the throttle valve opening θT when the EGR function is operating normally with respect to the engine load at engine speed N2.
HO and the actual throttle valve opening θTl (when the EGR function is abnormal) are compared. First, when the EGR function is normal, the engine load and the throttle valve opening OTHO are shown by the solid line. However, there is a tolerance range a (shaded area) due to differences in the engine and EGR device, but this tolerance range a is considered to be a deteriorating factor from the perspective of exhaust gas regulations. managed to the extent that it does not occur.

Next, if the EGR function fails to the open side due to the EGR valve getting stuck, etc., compare the engine air-fuel ratio when the engine air-fuel ratio is normal in the EGR region between the low rotation limit load and the high rotation limit load of the engine load in the diagram. Therefore, in order to obtain the required output, the throttle valve opening degree θTH shifts to the open direction as shown by the dashed line. Conversely, if the EGR function fails to the closed side due to, for example, sticking of the EGR valve or clogging of the piping passage, the engine air-fuel ratio in the EGR region will become richer than when it is normal, and in many vehicles, the output will increase. Therefore, the throttle valve opening degree θTH shifts in the closing direction as shown by the broken line. By monitoring the opening degree of the air flow rate control throttle valve in the EGR region of such an engine, E
Be able to determine whether the GR function is good or not, or whether it is malfunctioning and display the details.

FIG. 4 is a block diagram of an electronic internal combustion engine control device showing an embodiment of a failure diagnosis device for an EGR device according to the present invention. In Fig. 4, 1 is an internal combustion engine, 2 is an intake pipe, 3 is an exhaust pipe, 4 is a speed sensor, 5 is an intake air amount sensor (engine load sensor), 6 is a throttle valve, 7 is an opening sensor, and 8 is a EGR
9 is an ignition device, 10 is a fuel supply device, 11 is a calculation device (control device), 12 is an engine temperature sensor, 13
ゝ is an alarm means, and 14 is a passage. In Pekko's electronic internal combustion engine control device equipped with a failure diagnosis device for the EGR device, a passage 14 is provided between the passages 14 for recirculating part of the exhaust gas from the exhaust pipe 3 of the internal combustion engine 1 to the intake pipe 2.
An EGR valve 8 is provided for opening and closing the EGR valve 8.
The R valve 8 is driven by a calculation device (control device 11) to constitute an EGR device that controls the amount of exhaust gas recirculated. A throttle valve 6 is provided for controlling the amount of air to be supplied, and an opening sensor 7 is connected to the throttle valve 6 to generate an opening signal θTH in synchronization with the throttle valve 6.

The calculation device 11 includes various sensors such as a speed signal N of the speed sensor 4 of the internal combustion engine 1, a signal of the intake air amount sensor (engine load sensor) 5, a throttle valve opening signal θTH, and a signal of the temperature sensor 12 of the internal combustion engine 1. A similar signal is input. Arithmetic device 11
operates the internal combustion engine 1 by controlling the ignition device 9 of the internal combustion engine 1, as well as various actuators such as the fuel supply device 10 and the EGR valve 8, using control data calculated based on the information of these input signals. The throttle valve opening OTHO when the EGR function is normal as shown in the figure is compared with the actual throttle valve opening OT++, and in the event of a failure or abnormality, the alarm means 13 displays the details of the failure using a lamp or the like.

In this embodiment, an intake air amount sensor is used as the engine load sensor 5, but a method of detecting the engine load based on intake pipe pressure may also be used, for example.

Any method that can detect or calculate the engine load can be similarly applied.

Note that the above-mentioned engine state is not limited to engine speed and engine load.

As described above, according to this embodiment, NOx in exhaust gas
To monitor the function of the EGR device to reduce
The causal relationship between the engine state and the throttle valve opening when the GR function is normal is stored in memory, and the relationship is reflected when an abnormality occurs in the EGR system based on the throttle valve opening when the EGR function is normal. By interpreting engine fluctuations as differences in throttle valve opening, system failures in the EGR system can be diagnosed and an alarm can be displayed to indicate the details of the failure.

〔Effect of the invention〕

According to the present invention, it is possible to monitor whether the EGR function of the EGR device is normal or not without the need for a new device, and to accurately and accurately determine all failure modes of the EGR system. An economical and highly reliable failure diagnosis device for EGR equipment is provided that eliminates price increases, and can self-check the EGR function while installed in the vehicle and display a warning before complete damage occurs, reducing air pollution caused by exhaust gas. It is effective in preventing.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a failure diagnosis device for an EGR device according to the present invention, FIG. 2 is an explanatory diagram of a throttle valve opening degree map of the search means in FIG. 1, and FIG. FIG. 4, which is an explanatory diagram of the discrimination operation of the discrimination means, is a block diagram of an electronic internal combustion engine control device showing an embodiment of a failure diagnosis device for an EGR device according to the present invention. 1... Internal combustion engine, 2... Intake pipe, 3... Exhaust pipe,
4... Engine speed sensor, 5... Engine load sensor (intake air amount sensor), 6... Throttle valve, 7... Throttle valve opening sensor, 8... EGR valve, 11... Control device (computing device). 12...Temperature sensor, 13...Alarm means, 14...
·aisle.

Claims (3)

[Claims] 1. An exhaust gas recirculation device for an internal combustion engine, which comprises a passage for recirculating part of the exhaust gas of the internal combustion engine to an intake passage, a valve for opening and closing this passage, and means for energizing the operation of the valve, a throttle valve opening sensor that detects the opening of a throttle valve that controls the amount of air supplied to the internal combustion engine;
an operating state detection means for detecting the operating state of the internal combustion engine; a means for storing in advance a predetermined correspondence between the throttle valve opening and the operating state of the internal combustion engine when the function of the exhaust gas recirculation device is normal; means for determining that the function of the exhaust gas recirculation device is abnormal and displaying a failure when the correspondence between the detected throttle valve opening and the operating state of the internal combustion engine differs from a pre-stored predetermined correspondence by more than a predetermined amount; A fault diagnosis device for exhaust gas recirculation equipment consisting of: 2. 2. The failure diagnosis device for an exhaust gas recirculation system according to claim 1, wherein the operating state of the internal combustion engine is the rotational speed and load state of the internal combustion engine. 3. The means for storing the predetermined correspondence relationship in advance is to set the correspondence relationship between the throttle valve opening, the rotational speed of the internal combustion engine, and the load within a predetermined region including the exhaust gas recirculation operation region, and to store the absolute value in a grid pattern. Claim 1 as assigned
A failure diagnosis device for an exhaust gas recirculation device as described in 2.