KR100219453B1 - Egr monitoring method - Google Patents

Abstract

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Description

How to monitor EGR

The present invention relates to an EGR monitoring method for allowing a vehicle to determine whether an exhaust system is broken according to a temperature of exhaust gas partially introduced into an intake system in an exhaust gas recirculation system.

In general, in order to reduce the amount of harmful nitrogen oxides (NOx) in the exhaust gas discharged from the vehicle, it is called an exhaust gas recirculation apparatus (hereinafter abbreviated as EGR) to recycle a part of the exhaust gas to the intake machine.

By recirculating the exhaust gas, the filling rate of the new mixer is lowered. In particular, since the exhaust gas is no longer able to combust, the combustion temperature during the power stroke is lowered, thereby producing NOx. Significantly reduced.

However, while the exhaust gas recirculation is effective for reducing NOx, it does not reduce the amount of hydrocarbons (HC) or carbon monoxide (CO) in the exhaust gas, so the ignition of the mixer becomes worse and the output of the engine is greatly reduced. As a result, only an operating region having a large amount of nitrogen oxides (NOx) is selected so that an appropriate amount of exhaust gas is recycled only in this region.

Nitrogen oxides (NOx) are usually produced when the temperature and pressure of the combustion chamber are high and at the same time excessive air supply, and are known to increase in proportion to the traveling speed. In the case of a full-load operation, the exhaust gas is usually recycled only during the part load without recirculating the exhaust gas.

On the other hand, the exhaust gas is recycled as shown in FIG. 4, so that the exhaust gas introduced into the intake machine from the exhaust manifold 11 through the recycle passage 20 is usually introduced through the intake machine side EGR valve 21. The EGR valve 21 is operated by an EGR solenoid valve 23 controlled by an electronic control unit (hereinafter, referred to as ECU) that checks the rotation speed and the load of the engine 10. To be controlled.

However, in such a configuration, the exhaust gas is introduced into the intake machine at the time of idle when the EGR valve 21 is opened and is not sticked and the exhaust gas is recycled, thereby greatly reducing the combustion temperature of the engine. They may even shut down the engine or generate a large amount of exhaust gas.

In addition, while the recirculation passage 20 which induces the exhaust gas from the exhaust manifold 11 to the intake machine is blocked or leaking, the exhaust gas is not properly introduced at the same time as the part load. As a result, the combustion temperature of the engine is rapidly increased, thereby causing excessive generation of nitrogen oxides.

Accordingly, the present invention is to compensate for the correction in view of the above problems, the intake machine is equipped with an intake air temperature sensor, and the exhaust pipe guided by the intake machine is equipped with an EGR temperature sensor after warming up (WARMING UP) An object of the present invention is to provide a method for checking an engine speed in an ECU to determine whether a failure of an EGR system depends on a temperature of exhaust gas induced to an intake system according to an engine driving state.

In addition, the present invention has another object to maintain a more stable engine drive by allowing the vehicle to immediately determine the failure of the EGR valve to alert the driver immediately.

The present invention to achieve the above object

During the warm-up after idling, the EGR temperature recycled by the exhaust temperature sensor installed in the recirculation path between the EGR valve and the intake machine is checked to compare with the EGR control duty cycle which indicates the maximum change in the EGR temperature according to the preset intake temperature. The EGR system is configured to determine whether or not the EGR system is faulty by comparing the number of checks with a preset number of checks in the section of the EGR control duty cycle equal to or greater than a preset maximum temperature value. .

In addition, the engine checks the EGR temperature recycled by the exhaust temperature sensor installed in the recirculation path between the EGR valve and the intake machine when the part is loaded, and compares it with the EGR control duty cycle indicating the minimum change in the EGR temperature according to the preset engine speed. However, it is possible to determine whether the failure of the EGR system is determined by comparing the number of checks and the predetermined count that the checked EGR temperature is equal to or less than the predetermined minimum temperature value within the section of the EGR control duty cycle. This is a feature.

1 is a structural diagram of an embodiment according to the present invention

2 is a flow diagram of an embodiment of operation according to the present invention.

3 is a flowchart of another embodiment operation according to the present invention.

4 is a conventional EGR structure diagram

* Explanation of symbols for main parts of the drawings

10: engine 20: recirculation passage

21: EGR valve 22: exhaust temperature sensor

30: surge tank 31: intake air temperature sensor

40: Electronic control unit (ECU)

This will be described in more detail with reference to the accompanying drawings.

1 shows an embodiment according to the invention, where 11 is an exhaust manifold and 30 is a surge tank.

The exhaust manifold 11 is connected to the recirculation passage 20 between the surge tank 30 and the recirculation passage 20 is controlled by an EGR control solenoid valve 23 whose operation is controlled by electronic control. An EGR valve 21 is interposed to open and close the operation.

In the present invention, the exhaust temperature sensor 22 is mounted in the recirculation passage 20 between the EGR valve 21 and the surge tank 30 of the intake machine, and the intake air temperature sensor 31 is provided in the surge tank 30. And the exhaust temperature sensor 22 and the intake temperature sensor 31 are connected to the ECU 40, and together with the signals from each of the sensors 22 and 31, This configuration allows the EGR system to be judged as a result of comparison with the set EGR control duty cycle.

To this end, the ECU 40 has an exhaust temperature change cycle according to the change in intake air temperature or engine speed according to the engine operating state after the engine 10 is warmed up, and that is, a constant section, that is, the minimum change value and the maximum change value as modeling values. In order to be mapped, in particular, the cycle is divided into a predetermined check interval and the interval as a plurality of count points.

That is, when the vehicle enters the idle state after warming up, as shown in FIG. 2, the ECU 40 checks the intake air temperature from the intake air temperature sensor 31 so that the intake air temperature of the preset EGR control duty cycle is changed according to the intake air temperature change. It is determined whether it is within the check section, and if it is within the check section, the EGR temperature corresponding to the count point of the intake air temperature in the check section is checked and compared with the preset temperature value.

At this time, if the EGR temperature is smaller than the preset maximum temperature value, it is determined to be normal, but if it is checked to be large, enter count 1, and if the count is smaller than the preset count number, compare the EGR temperature and the set temperature again. If it returns and it is checked again that the exhaust temperature is less than the preset exhaust temperature, the count is increased by one.

In this way, the above steps are repeated until the number of counts reaches the preset number of counts. When the number of counts is finally reached, a failure of the EGR system is determined.

In addition, unlike the above, it is determined whether the exhaust temperature is checked within a predetermined section of the EGR control duty cycle indicating the minimum change amount of the EGR temperature according to the engine speed, as shown in FIG. At this time, if the exhaust temperature is checked above the preset minimum temperature value, it is judged as normal, but if it is checked below, input count 1, and if the count number is smaller than the preset count number, compare the EGR temperature and the set temperature again. If it is checked that the exhaust temperature is smaller than the preset minimum temperature value again, the count is increased by one.

In this way, the above steps are repeated until the number of counts reaches the preset number of counts. When the number of counts is finally reached, a failure of the EGR system is determined.

Therefore, in the present invention, the intake air temperature sensor 31 is mounted to the intake air, and the exhaust temperature sensor 22 is mounted to the recirculation passage 20 between the EGR valve 21 and the intake air. ) And the temperature value from the exhaust temperature sensor 22 are checked by the ECU 40 to determine whether the EGR system has failed as a change in the exhaust temperature according to the intake air temperature or the engine speed.

Meanwhile, in the structure as described above, the warning means 60 such as a lamp or a buzzer is separately connected to the ECU 40 so that the driver can be notified immediately by operating it when determining a failure from the ECU 21.

Reference numeral 50 in the drawings is a throttle valve.

Such monitoring is intended for the vehicle to self-diagnose the operability of the EGR system by checking the exhaust temperature at which the engine is re-supplied to the engine at idle or part load.

That is, the ECU 40 has already set the modeling value of the exhaust temperature according to the intake temperature and the modeling value of the exhaust temperature according to the engine speed as a predetermined section, as described above, and sets the idle or part load. To check whether the exhaust temperature from the exhaust temperature sensor 22 mounted in the recirculation passage 20 between the EGR valve 21 and the intake air is out of the predetermined exhaust temperature check section, and determine whether the EGR system is broken. will be.

Such failure determination is not normally recirculating the exhaust gas, in particular because the engine operation during idle operation is operated at the minimum output, while the exhaust temperature detected from the exhaust temperature sensor 22 is larger than the maximum value of the modeling value. Checking means that the EGR valve 21 is stuck in the open state, and thus the ECU 40 determines that the failure is a failure.

On the other hand, at the time of the part load to recycle the exhaust gas, although the exhaust gas is recycled and the high temperature exhaust gas is introduced into the intake machine, even though a temperature higher than a predetermined temperature must be detected from the exhaust temperature sensor 22, the exhaust temperature sensor ( When the temperature checked from 22) does not reach the minimum value of the preset exhaust temperature, it means that blocking or leaking has occurred in the exhaust gas recirculation system, so that the ECU 40 immediately determines that it is a failure.

Therefore, the exhaust gas is not properly circulated in the section where the exhaust gas is to be recycled due to the abnormality of the exhaust gas recirculation system during engine operation, and on the contrary, in the section that should not be recycled, the exhaust gas flows into the intake machine, causing engine relief. It can be prevented in advance.

In particular, if it is determined that the failure of the EGR system by the above method to alert the driver immediately to be able to respond quickly it is possible to prevent the serious failure of another control system in advance.

Therefore, the present invention checks the operation of the EGR system very precisely by checking the exhaust temperature set by the intake temperature or the engine rotational speed according to the intake temperature or the engine rotational speed according to the engine operation state, and the operation of the EGR system very precisely. When it occurs, it is notified to the driver quickly so that they can take immediate action and at the same time have a very useful effect to further improve the engine performance and durability.

Claims (6)

After warming up, check the EGR temperature recycled by the exhaust temperature sensor installed in the recirculation path between the EGR valve and the intake machine, and compare it with the EGR control duty cycle indicating the maximum change in the EGR temperature according to the preset intake temperature. An EGR monitoring method for idling so that a failure of an EGR system can be determined by comparing a count of a temperature checked below a reference value within a predetermined section of the EGR control duty cycle with a preset count. The method of claim 1, Checking the intake air temperature from the intake air temperature sensor 31 when the vehicle enters the idle state after warming up; Determining whether the intake temperature is within a check section of a preset EGR control duty cycle; Checking an EGR temperature corresponding to a count point of intake air temperature in the check section and comparing the temperature with a preset temperature value; If it is checked that the checked EGR temperature is greater than the preset temperature value, enter the count 1, and then return to the step of comparing the EGR temperature with the set temperature.If it is again checked that the exhaust temperature is smaller than the preset exhaust temperature, the count is increased by one. Increasing; Repeating the above steps until the number of counts reaches a preset number of counts and determining a failure of the EGR system when the number of counts reaches the set number of counts; EGR monitoring method of children at the time characterized by the process consisting of. According to claim 2, EGR monitoring method characterized in that when it is determined that a failure occurs in the EGR system during the monitoring the power to the warning means, such as lamps or buzzers to notify the driver immediately. The engine checks the EGR temperature recycled by the exhaust temperature sensor installed in the recirculation path between the EGR valve and the intake system during operation, and compares it with the EGR control duty cycle indicating the minimum change in the EGR temperature according to the preset engine speed. Characterized in that the EGR system can be judged whether or not the EGR system malfunctions by comparing the count number of which the EGR temperature is equal to or less than the reference value within the preset period of the EGR control duty cycle and the preset count number. How to monitor EGR at part load. The method of claim 4, wherein Checking the exhaust temperature when the engine is in a part load state during operation; Determining whether the exhaust temperature is within a check section of a predetermined EGR control duty cycle according to the engine speed; Checking an EGR temperature corresponding to a count point of a preset exhaust temperature in the check section and comparing the temperature with a preset temperature value; If the checked EGR temperature is less than the preset temperature, enter count 1, and if the count is less than the preset count, return to the step of comparing the EGR temperature and the set temperature again. Increasing the count by one if checked to be less than temperature; Repeating the above steps until the number of counts reaches a preset number of counts and determining a failure of the EGR system when the number of counts reaches the set number of counts; EGR monitoring method at the time of part load characterized by the process consisting of. The method of claim 5, EGR monitoring method characterized in that when the monitoring determines that a failure occurs in the EGR system as soon as the power is supplied to the warning means such as lamps or buzzers.