Egr apparatus of engine

Patent metadata

Field	Value
Publication number	US-2019107064-A1
Application number	US-201816150396-A
Country	US
Kind code	A1
Filing date	Oct 3, 2018
Priority date	Oct 5, 2017
Publication date	Apr 11, 2019
Grant date	—

Abstract

An EGR apparatus includes an EGR passage to allow part of exhaust gas discharged from an engine to an exhaust passage to flow as EGR gas into an intake passage; an EGR valve to regulate an EGR flow rate in the EGR passage; various sensors for detecting an engine running state; and an ECU to control the EGR valve based on the detected running state to diagnose abnormality in the EGR valve. The ECU calculates a reference intake pressure according the detected engine rotation speed and load by reference to a reference intake pressure map showing a relationship of the reference intake pressure to engine rotation speed, and engine load, and determine whether or not the EGR valve has abnormality in opening/closing by comparing the reference intake pressure with the detected intake pressure.

First claim

What is claimed is:

1 . An EGR apparatus of an engine, the EGR apparatus comprising:
an EGR passage configured to allow part of exhaust gas discharged from the engine to an exhaust passage to flow as EGR gas from the exhaust passage to an intake passage in order to recirculate the EGR gas into the engine; an EGR valve configured to regulate a flow rate of the EGR gas in the EGR passage, the EGR valve including a valve seat, a valve element provided to be seatable on the valve seat, and an actuator to move the valve element; a running-state detecting unit configured to detect a running state of the engine; an EGR valve control unit configured to control the EGR valve based on the detected running state; and an EGR valve abnormality diagnosing unit configured to diagnose abnormality in opening/closing between the valve seat and the valve element of the EGR valve based on the detected running state, wherein the running-state detecting unit includes:
an intake pressure detecting unit configured to detect intake pressure in the intake passage downstream of a position where the EGR gas flows from the EGR passage into the intake passage;
a rotation speed detecting unit configured to detect a rotation speed of the engine; and
a load detecting unit configured to detect a load of the engine, and
the EGR valve abnormality diagnosing unit is configured to determine whether or not the EGR valve has the abnormality by comparing a reference intake pressure calculated based on the detected rotation speed and the detected load with the detected intake pressure or by comparing a reference opening degree of the EGR valve calculated based on the detected rotation speed, the detected load, and the detected intake pressure with a control opening degree of the EGR valve under control by the EGR valve control unit.

2 . The EGR apparatus of an engine according to claim 1 , wherein
the EGR valve abnormality diagnosing unit is provided with a reference function map or a reference function expression previously set to show a relationship of the reference intake pressure to the rotation speed and the load, and the EGR valve abnormality diagnosing unit is configured to calculate the reference intake pressure according to the detected rotation speed and the detected load by reference to the reference function map or the reference function expression, and determine whether or not the EGR valve has the abnormality by comparing the calculated reference intake pressure with the detected intake pressure.

3 . The EGR apparatus of an engine according to claim 1 , wherein
the EGR valve abnormality diagnosing unit is provided with a reference function map or a reference function expression previously set to show a relationship of the reference opening degree of the EGR valve to the rotation speed, the load, and the intake pressure, and the EGR valve abnormality diagnosing unit is configured to calculate the reference opening degree according to the detected rotation speed, the detected load, and the detected intake pressure by reference to the reference function map or the reference function expression, and determine whether or not the EGR valve has the abnormality by comparing the calculated reference opening degree with the control opening degree.

4 . The EGR apparatus of an engine according to claim 1 , wherein the EGR valve abnormality diagnosing unit is configured to start diagnosing the abnormality when the the EGR valve abnormality diagnosing unit determines that a predetermined delay time has elapsed from start of deceleration of the engine based on the detected running state.

5 . The EGR apparatus of an engine according to claim 2 , wherein the EGR valve abnormality diagnosing unit is configured to start diagnosing the abnormality when the the EGR valve abnormality diagnosing unit determines that a predetermined delay time has elapsed from start of deceleration of the engine based on the detected running state.

6 . The EGR apparatus of an engine according to claim 3 , wherein the EGR valve abnormality diagnosing unit is configured to start diagnosing the abnormality when the the EGR valve abnormality diagnosing unit determines that a predetermined delay time has elapsed from start of deceleration of the engine based on the detected running state.

7 . The EGR apparatus of an engine according to claim 4 , wherein the EGR valve abnormality diagnosing unit is configured to set the delay time longer as the detected rotation speed is lower.

8 . The EGR apparatus of an engine according to claim 5 , wherein the EGR valve abnormality diagnosing unit is configured to set the delay time longer as the detected rotation speed is lower.

9 . The EGR apparatus of an engine according to claim 6 , wherein the EGR valve abnormality diagnosing unit is configured to set the delay time longer as the detected rotation speed is lower.

10 . The EGR apparatus of an engine according to claim 2 , wherein
when the engine is in deceleration and the EGR valve control unit controls the EGR valve to close to a valve-closed state, the EGR valve abnormality diagnosing unit is configured to determine whether or not the EGR valve has the abnormality by comparing the calculated reference intake pressure with the detected intake pressure.

11 . The EGR apparatus of an engine according to claim 2 , wherein
when the engine is in deceleration and the EGR valve control unit the EGR valve to close to a valve-closed state, the EGR valve abnormality diagnosing unit is configured to determine whether or not the abnormality by comparing a decrease rate of the detected intake pressure with a predetermined decrease rate.

12 . The EGR apparatus of an engine according to claim 2 further including a foreign-matter removal control unit,
wherein when it is determined that the EGR valve has the abnormality, the foreign-matter removal control unit is configured to:
obtain an opening degree corresponding to a diameter of a foreign matter lodged between the valve seat and the valve element based on the detected intake pressure and the calculated reference intake pressure; and
execute a foreign-matter removal control that controls the actuator to open the valve element at a larger opening degree than the obtained opening degree corresponding to the diameter of the foreign matter to remove the foreign matter from between the valve seat and the valve element.

13 . The EGR apparatus of an engine according to claim 3 further including a foreign-matter removal control unit,
wherein when it is determined that the EGR valve has the abnormality, the foreign-matter removal control unit is configured to:
obtain an opening degree corresponding to a diameter of a foreign matter lodged between the valve seat and the valve element based on the calculated reference opening degree and the control opening degree, and
execute a foreign-matter removal control that controls the actuator to open the valve element at a larger opening degree than the obtained opening degree corresponding to the diameter of the foreign matter to remove the foreign matter from between the valve seat and the valve element.

14 . The EGR apparatus of an engine according to claim 12 , wherein
the foreign-matter removal control unit is configured such that when the engine is in deceleration and fuel supply to the engine is cut off, the, foreign-matter removal control unit immediately executes the foreign-matter removal control, and when the engine is in deceleration and the fuel supply is not cut off, the foreign-matter removal control unit executes the foreign-matter removal control when an opening degree of

Assignees

• Aisan Ind

Inventors

• Yoshioka Mamoru

Classifications

• F02D41/22

  Safety or indicating devices for abnormal conditions {(in air/fuel ratio feedback systems F02D41/1495, in electric control linkage F02D11/107, in purge control systems F02M25/0809)} · CPC title

• F02D41/0077 Primary

  Control of the EGR valve or actuator, e.g. duty cycle, closed loop control of position (EGR valve position sensor F02M26/48) · CPC title

• F02M26/49 Primary

  Detecting, diagnosing or indicating an abnormal function of the EGR system · CPC title

• F02D41/0052

  Feedback control of engine parameters, e.g. for control of air/fuel ratio or intake air amount · CPC title

• F02D2200/0408

  Estimation of intake manifold pressure · CPC title