JP2659367B2 - Failure diagnosis device for exhaust gas recirculation device - Google Patents

Description

The present invention relates to a failure diagnosis of an EGR device for monitoring and diagnosing an operation function of an exhaust gas recirculation device (hereinafter referred to as an EGR device) of an internal combustion engine. Related to the device.

[Conventional technology]

As a method of diagnosing the operating state of the EGR device in a conventional vehicle state, and measuring the NO _x concentration in the exhaust gas at a service factory Deira like. However, this method requires an exhaust gas analyzer and is not a method that can easily diagnose the function of the EGR device. Further, as another method, for example, as disclosed in Japanese Patent Application Laid-Open No. 57-212343, there is provided a means for detecting a movement of a valve body of an EGR valve of an EGR device. However, this method can detect a failure of a rod connected to a valve body of an EGR valve body, but cannot detect a systematic abnormality in an operation function of the EGR device.

[Problems to be solved by the invention]

The above prior art is a simple diagnostic method that can detect a failure of a rod portion connected to a valve body of an EGR valve body, but for example, includes an EGR valve including a blockage of a piping system or a loose valve body.
No consideration was given to detecting the operation function of the device, and there was a problem that systematic abnormality detection of the EGR function could not be performed.

The object of the present invention is to solve the above-mentioned problems of the prior art,
An object of the present invention is to provide a failure diagnosis device for an EGR device capable of accurately diagnosing a failure of a system function of the EGR device in a vehicle-mounted state.

[Means for solving the problem]

The above object is to monitor the causal relationship between the opening degree of the air flow restrictor disposed in the intake passage determined by the engine state of the engine speed and the engine load and the fluctuation of the engine air-fuel ratio, thereby making the EGR device abnormal. This is achieved by a failure diagnosis device of the EGR device which is configured to determine

[Action]

The throttle valve opening for controlling the amount of intake air for the engine has a predetermined correspondence from a desired air-fuel ratio determined by the rotational speed of the engine and the state of the load. It is based on the EGR rate (the intake air amount is the ratio of the exhaust gas recirculation amount) set for gas NO _x restriction. When an abnormality occurs in the EGR grassland, the throttle valve opening degree Based on the facts clarified by the experiments of the present inventors, the failure diagnosis of the EGR device is performed based on the difference between the predetermined correspondence between the throttle valve opening and the engine state and the actual correspondence. I can do it.

〔Example〕

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

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

FIG. 2 is an explanatory diagram of the throttle valve opening map of the search means 11A of FIG. This map is a three-dimensional map representing the throttle valve opening θ _THO based on the engine speed N and the engine load L, and holds the above three engine elements in advance in a normal state of the EGR function as matrix data related in a matrix form. . If the allocation of the engine speed N and the engine load L is limited to the EGR region of the engine, the capacity of the memory and the like becomes advantageous, and each division point and the number of grids can be arbitrarily set by the EGR region. I just need.

FIG. 1 shows that the speed signal N of the engine speed sensor 4 and the load signal L of the engine load sensor 5 are stored in the search means 11 of the control device 11, respectively.
Entered into A. The retrieval means 11A retrieves a predetermined throttle valve opening map from the input speed N and load L according to the request for engine performance shown in FIG. 2, and outputs throttle valve opening data θ _THO to the determination means 11B. The actual throttle valve opening signal θ _TH of one throttle valve opening sensor 7 is also input to the determination means 11B.

The next determination means 11B compares the data θ _THO obtained from the _map with the actual data θ _TH, and when the difference between these two data is equal to or more than a predetermined value, determines that the function of the EGR device is abnormal and outputs By outputting the signal AL to the alarm means 13,
Displays the failure content of the R device. The output signal AL from the discriminating means 11B is limited by the temperature signal from the temperature sensor 12 of the engine is added, for example, deviation of the data theta _THO actual data theta _TH for generate less of the NO _x when the predetermined temperature below the predetermined Even if the value is equal to or more than the value, the alarm unit 13 is not activated.

FIG. 3 is an explanatory diagram of an abnormality determining operation of the determining means 11B of FIG. This explanatory diagram shows the relationship between the engine load L at the engine speed Nα partially extracted from the throttle valve opening map in FIG.
Throttle valve opening θ when EGR function is operating normally
_The comparison between _THO and the actual throttle valve opening θ _TH when the EGR function is abnormal is shown. First, when the EGR function is normal, there is a fixed causal relationship between the engine load L and the throttle valve opening θ _{THO as} shown by a solid line. However, here, there is an allowable range a (hatched portion) due to the difference between the engine and the EGR device or the like, but the allowable range a is managed to such an extent that it does not become a deteriorating factor in terms of exhaust gas regulations.

Next, if the EGR function fails on the open side due to, for example, the catch of an EGR valve, the engine air-fuel ratio is normal in the EGR region between the low-speed limit load and the high-speed limit load of the engine load L in the figure. The throttle valve opening degree θ _TH shifts in the opening direction as shown by the dashed line so as to obtain the required output because it is leaner. Conversely, if the EGR function fails on the closed side due to, for example, adhesion of an EGR valve or clogging of a pipe passage, the engine air-fuel ratio in the EGR region becomes higher than normal, and the output of many vehicles improves. Therefore, the throttle valve opening degree θ _TH shifts in the closing direction as shown by the broken line. By monitoring the degree of opening of the air flow control throttle valve in the EGR region of such an engine, it is possible to determine whether or not the EGR function is defective or to have a failure and to display the content.

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, 8 is EGR
A valve, 9 is an ignition device, 10 is a fuel supply device, 11 is a computing device (control device), 12 is an engine temperature sensor, 13 is alarm means, and 14 is a passage.

In the electronic internal combustion engine control device provided with the failure diagnosis device for the EGR device, the passage 14 is opened and closed in the middle of the passage 14 for recirculating a part of the exhaust gas of the exhaust pipe 3 of the internal combustion engine 1 to the intake pipe 2. An EGR valve 8 is provided for controlling the exhaust gas ring flow rate by driving the EGR valve 8 by a computing device (control device) 11. Further, an internal combustion engine 1 is provided between an intake flow rate sensor (engine load sensor) 5 and the intake pipe 2.
A throttle valve 6 for controlling the amount of air supplied to the throttle valve 6 is provided. An opening sensor 7 is connected to the throttle valve 6 to generate an opening signal θ _TH synchronized with the throttle valve 6.

The arithmetic unit 11 includes various signals 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 θ _TH, and a signal of the temperature sensor 12 of the internal combustion engine 1. Sensor signals are input. The arithmetic unit 11 operates the internal combustion engine 1 by controlling various actuators such as the fuel supply device 10 and the EGR valve 8 in addition to the ignition device 9 of the internal combustion engine 1 based on control data calculated based on the information of these input signals. A comparison determination is made between the throttle valve opening θ _THO and the actual throttle valve opening θ _{TH in} the normal state of the EGR function similar to FIG.
In the event of a failure or abnormality, the contents of the failure are displayed by the alarm means 13 such as a lamp.

In this embodiment, an intake air amount sensor is used as the engine load sensor 5. However, for example, a method of detecting the engine load based on the intake pipe pressure may be used, and any method capable of detecting or calculating a period load is similarly applicable. It is.

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

According to this embodiment, as described above, to monitor the function of the EGR device for reducing NO _x in the exhaust gas, a causal relationship between the throttle valve opening EGR function and engine normal state By storing in a memory, and taking the engine fluctuation reflected when an abnormality occurs in the EGR device based on the throttle valve opening at the time of normality of this EGR function as a difference in the throttle valve opening,
Diagnosis of system failure of the EGR device can be displayed as an alarm.

〔The invention's effect〕

According to the present invention, all the failure modes of the EGR system can be accurately and accurately determined by monitoring whether or not the EGR function of the EGR device is normal without requiring a new device. A cost-effective and highly reliable EGR device failure diagnosis device is provided without any price increase.
The self-checking of the GR function can display an alarm before it is completely damaged, so the exhaust gas is effective in preventing air pollution.

[Brief description of the drawings]

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 map of a retrieval means of FIG. 1, and FIG. 3 is a diagram of FIG. 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. 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 ... passage.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yasuji Hasegawa 2520 Takada, Katsuta City Inside Sawa Plant, Hitachi, Ltd. (56) References JP-A-61-182450 (JP, A) JP-A-58- 47149 (JP, A) JP-A-55-123345 (JP, A) JP-A-61-81567 (JP, A)

Claims (3)

(57) [Claims] An exhaust gas for an internal combustion engine comprising a passage for recirculating a part of the exhaust gas of the internal combustion engine to an intake passage, a valve for opening and closing the passage, and a means for energizing the operation of the valve. A throttle valve opening sensor for detecting an opening of a throttle valve for controlling an amount of air supplied to the internal combustion engine; an operating state detecting means for detecting an operating state of the internal combustion engine; 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 recirculation device is normal; the operating state of the internal combustion engine detected by the operating state detecting means; The function of the exhaust gas recirculation device is abnormal when the throttle valve opening obtained from the correspondence stored in the throttle valve opening and the actual throttle valve opening detected by the throttle valve opening sensor differ by a predetermined amount or more. Judgment and failure display Trouble diagnosis device for an exhaust gas recirculation device comprising a that means. 2. A malfunction of the exhaust gas recirculation system according to claim 1, wherein said operating state detecting means for detecting an operating state of the internal combustion engine detects a rotational speed and a load state of the internal combustion engine. Diagnostic device. 3. The exhaust gas recirculation means according to claim 1, wherein said predetermined correspondence relation is stored in advance. The correspondence relation between the throttle valve opening, the rotation speed of the internal combustion engine, and the load state when the function of the exhaust gas recirculation device is normal. 2. The failure diagnosis device for an exhaust gas recirculation device according to claim 1, wherein the failure diagnosis device is set within a predetermined region including an operation region and its absolute value is allocated in a grid pattern.