JPS62159756A - Exhaust gas recirculating device for engine - Google Patents

Abstract

PURPOSE:To make it possible to simply and surely confirm the function of an EGR device without any new device being added, by detecting changes in the amount of EGR in the form of variations in the concentration of exhaust gas in order to discriminate where the function of the EGR device is good or not. CONSTITUTION:An engine 1 has an exhaust passage 14a, 14b for recirculating a part of exhaust gas into an intake manifold 2, in an exhaust manifold, and an EGR valve 5 is disposed in the intermediate section of the exhaust passage 14a, 14b. Further, a control computer 4 controls the EGR valve 5 and a fuel injection valve 6 in accordance with signals from a rotating angle sensor 12, an intake-air volume sensor 8, an oxygen sensor 3, an opening degree detector 15 and a detector 11 for detecting the operating condition of the engine including the temperature of the latter. Further, the EGR valve 5 is operated in, for example, a stepwise manner in a predetermined condition of the engine 1. Further, when the the amount of EGR is large, it is monitored that a signal from the oxygen sensor 10 turns into the lean side to discriminate whether the function of the EGR valve is good or not.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an engine exhaust gas recirculation (hereinafter referred to as EGR) device, and particularly to an engine EGR device suitable for checking the functional operation of EGR.

[Conventional technology]

In recent years, as this type of device, Japanese Patent Application Laid-Open No. 52-125979
As described in the publication, the EGR amount is calculated and controlled based on engine information such as intake air amount and engine speed, thereby achieving a more accurate exhaust gas purification function. It has long been known from various documents that EGR devices have a great effect on reducing NOx.

However, this type of system is also based on the normal functioning of the EGR device, and for example, when the EGR valve malfunctions or when a malfunction occurs in the EGR valve control means, exhaust gas purification is required. This results in decreased performance, which in turn has a negative impact on air pollution.

The above-mentioned conventional technology does not take into account the confirmation of the operating functions of such device systems or the monitoring of the mounted state, and there are problems such as the fact that in Japan, it can only be detected during the process of vehicle inspection system etc. .

An object of the present invention is to provide an engine EGR device suitable for monitoring the EG'R function without requiring a new device and effectively utilizing existing functions.

[Means for solving problems]

The above object can be achieved by making the EGR amount have a causal relationship with the exhaust gas concentration (for example, the signal from the 02 sensor) in a predetermined state of the engine.

[Effect]

That is, in a predetermined state of the engine, the EGR amount is activated in steps, for example. Thereby, by monitoring that the signal of the 02 sensor changes to the lean side when the EGR amount is large, it can be confirmed whether the EGR device is operating normally.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 2 is a block diagram of an engine control device to which an embodiment of the present invention, which will be described later, is applied. In the figure, 8 is an intake air amount sensor that detects the amount of intake air, and 7 is an intake air amount sensor that supplies ignition energy to each cylinder of the engine. It is a distributor that has a built-in rotation angle sensor 12 that detects the rotation angle of the engine. 10
detects exhaust gas concentration. The two sensors are arranged in the passage of the exhaust manifold 3. 1 is the engine;
An intake manifold 2 equipped with a throttle valve 9 having an intake air amount sensor and an opening detector 15 is disposed on the upstream side thereof, and an exhaust manifold and a muffler 13 are disposed on the downstream side of the engine. The intake manifold is equipped with a fuel injection valve 6 for supplying fuel. Further, the exhaust manifold 3 is provided with exhaust passages 14a and 14b for recirculating part of the exhaust gas to the intake manifold 2.
An EGR valve is provided to control the R amount. 4 is an engine control computer.

Signals from the rotation angle sensor 12, intake air amount sensor 8, 02 sensor 3, opening detector 15, and other operating state detectors 11 such as engine temperature are input, and based on these signals, the fuel is determined. Fuel amount by injection valve 6 and E G, R
It is configured to calculate and control the amount of exhaust gas recirculation by the valve 5 and further the ignition timing. Note that 16 is an indicator that indicates, for example, a failure of the engine control device.

FIG. 1 shows an embodiment of the present invention, in which the engine control device shown in FIG. 2 shows the EG when the engine speed is fixed.
This figure shows the relationship between the R valve operation, the EGR amount, and the 02 sensor signal.

In this operating state, the EGR valve is operated for a predetermined period of time TE.
By operating to increase the EGR amount from small to large by energizing the ON side, the A/Fa degree supplied to the engine is made lean only during the TE time period. As a result, after the delay time TR through the process from intake to combustion, the OX sensor signal is reflected in the exhaust gas concentration and shifts to the lean side for a period of T^ (=Tε). Become.

FIG. 3 shows a schematic flowchart of the engine control device shown in FIG. 2 which realizes the functions shown in FIG. 1, and the functions of one embodiment will be explained using this flowchart. When the engine is started, the engine control computer repeatedly performs arithmetic processing at a predetermined cycle according to a predetermined control program to control each device (not shown). During this calculation operation, when the EGR check mode is reached, for example, the idle state, the process moves to the interrupt processing routine of step 100. If the 02 sensor is not in the active region, the process moves to step 116 and waits for the next interrupt request. On the other hand, 02
When the sensor is in the active region, the process moves from step 100 to step 101, where the EGR check counter is incremented, and the process moves to step 102, where the 02F/B control is stopped and the process moves to step 103. In step 103, the air-fuel ratio (
A/F) is fixed at a position that is slightly richer than the ternary point (stoichiometric air-fuel ratio 14.7). Next, in step 104, the EGR valve is operated for a predetermined time TE to move it to the side where the EGR amount increases, and the process moves to step 105. In step 105, it is determined whether the counter in step 101 has reached the desired value N times.

If it is less than N times, the process moves to step 108. Next step 1
08, wait for the delay time TR and proceed to step 109 o2.
The sensor signal is monitored from time TE to 2TE, and the lean side (
Measure the time that A/F exists at the point (larger than the 3-dimensional point). After this, the OzF/B is restarted in step 110, and the process moves to step 111, where it is determined whether the time measured in step 109 is greater than or equal to the desired time TE, and when it is less than TE, the EGRNG counter is incremented in step 112. do. On the other hand, if it is equal to or greater than TE, the process moves to step 116 and waits for the next interrupt request. Next, the process moves from step 112 to step 113, and it is determined whether or not the value of the EGRNG counter has reached NF times. When it has reached NF times, the process moves to step 114.

On the other hand, if the number is less than NF, the process moves to step 116 and waits for the next interrupt request.In step 114, the EGRFAIL flag is set, and in step 115, a warning indicating EGR function NG is displayed, and then the first interrupt is issued. I will wait for the request. Note that the EGR check counter and the EGRNG counter are activated in steps 106 and 107 when the EGR check counter reaches N times in step 105.
Clear with .

Here, the display at step 115 is typically the display 16 of the engine control device to which the embodiment of FIG. It may also be something that emits a signal.

As explained in the above example, if the exhaust gas concentration changes to the lean side when the EGR amount is increased, the EGR function is determined to be operating normally.On the other hand, even if the EGR amount is increased, the exhaust gas concentration does not change. If there is no EGR function, it is determined that the EGR function has been lost, and the essence is that the change in the EGR amount is detected as a change in the exhaust gas concentration to determine and confirm whether the EGR function is good or bad.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to check the EGR function without adding a new device, prevent cost increases due to functional improvements, and also make it possible to check the EGR function without adding a new device. It has the effect of allowing you to self-check the functions while driving.

Furthermore, since it is possible to check the EGR function of the entire engine control system, air pollution such as an increase in NOx due to EGR malfunction can be prevented, which is advantageous in terms of exhaust gas countermeasures.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the operational relationship between EGR amount and exhaust gas concentration according to an embodiment of the present invention, FIG. 2 is a configuration diagram of an engine control device to which the embodiment shown in FIG. 1 is applied, and FIG. 3 is a flowchart of one embodiment shown in the figure. 4...Engine control computer, 5...EGR
Valve, 10...Q2 sensor, 14a, 14b...
Exhaust 1 Figure 2

Claims (2)

[Claims] 1. An exhaust comprising an exhaust passage for recirculating exhaust gases to an intake manifold of the engine, a valve disposed in the exhaust passage for controlling exhaust gases passing through said passage, and means for energizing operation of said valve. In the recirculation device, the valve is opened for a desired time during desired operation of the engine, and the oxygen concentration in the exhaust gas shifts to the lean side.
An exhaust gas recirculation device for an engine, characterized in that it is provided with a monitoring means for monitoring the operation of an exhaust gas purification function. 2. The exhaust gas recirculation system for an engine according to claim 1 is characterized in that an alarm means is provided for displaying an alarm when the oxygen concentration in the exhaust gas does not shift to the lean side due to the opening of the valve. Engine exhaust recirculation device.