EXHAUST GAS RECIRCULATION APPARATUS FOR ENGINE

• US 20140290239A1
• Filed: 03/31/2014
• Published: 10/02/2014
• Est. Priority Date: 04/02/2013
• Status: Active Grant

• Current Assignee: Aisan Kogyo Kabushiki Kaisha
• Original Assignee: Aisan Kogyo Kabushiki Kaisha
• Inventors: AKITA, Minoru, YOSHIOKA, Mamoru
• Granted Patent: US 9,677,485 B2
• Time in Patent Office: Days
• US Class Current: 60/602
• CPC Class Codes: F02D 2011/104 using electric step motors
• CPC Class Codes: F02D 2041/2024 the control switching a load after time-on and time-off pulses
• CPC Class Codes: F02D 41/0077 Control of the EGR valve or actuator, e.g. duty cycle, closed loop control of position EGR valve position sensor F02M26/48
• CPC Class Codes: F02M 26/05 High pressure loops, i.e. wherein recirculated exhaust gas is taken out from the exhaust system upstream of the turbine and reintroduced into the intake system downstream of the compressor
• CPC Class Codes: F02M 26/54 Rotary actuators, e.g. step motors
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

An EGR apparatus includes an EGR passage to allow part of exhaust gas discharged from a combustion chamber to flow in an intake passage and recirculate back to the combustion chamber and an EGR valve to regulate EGR gas in the EGR passage. The EGR valve includes a valve seat, a valve element, and a step motor. An ECU calculates a target correction value corresponding to an operating condition of an engine, cuts off energization to the step motor in order to hold the EGR valve at a predetermined opening degree during operation thereof, and then restarts energization to the step motor, calculates an energization cutoff correction value corresponding to an elapsed time from energization cutoff, and corrects the target correction value by the calculated energization cutoff correction value in order to control the EGR valve to the target opening degree.

Claims

1. An exhaust gas recirculation apparatus for an engine, the apparatus including:

an exhaust gas recirculation passage to allow part of exhaust gas discharged from a combustion chamber of an engine to an exhaust passage to flow as exhaust recirculation gas into an intake passage and recirculate back to the combustion chamber;

a motor-driven exhaust gas recirculation valve provided in the exhaust gas recirculation passage to regulate a flow rate of the exhaust recirculation gas in the exhaust gas recirculation passage,

the exhaust gas recirculation valve including a valve seat, a valve element provided to be seatable on the valve seat, and a motor to drive the valve element; and

a control unit configured to control the exhaust gas recirculation valve according to an operating condition of the engine,

wherein the control unit is configured to;

calculate a target correction value corresponding to the operating condition of the engine;

cut off energization to the motor when the exhaust gas recirculation valve is to be held at a predetermined opening degree during operation of the exhaust gas recirculation valve; and

then

restart energization to the motor, calculate an energization cutoff correction value corresponding to an elapsed time since energization to the motor is cut off, and correct the target correction value by the calculated energization cutoff correction value when the exhaust gas recirculation valve is to be controlled to the target opening degree.

2. The exhaust gas recirculation apparatus for an engine according to claim 1, wherein

the control unit is configured to further calculate an energization start correction value corresponding to an elapsed time since energization to the motor is restarted and further correct the target correction value by the calculated energization start correction value.

3. The exhaust gas recirculation apparatus for an engine according to claim 1, wherein

the control unit is configured to limit calculation of the energization cutoff correction value in a range of a predetermined upper limit to a predetermined lower limit.

4. The exhaust gas recirculation apparatus for an engine according to claim 2, wherein the control unit is configured to limit calculation of the energization cutoff correction value in a range of a predetermined upper limit to a predetermined lower limit.

5. The exhaust gas recirculation apparatus for an engine according to claim 2, wherein

the control unit is configured to limit calculation of the energization start correction value in a range of a predetermined upper limit to a predetermined lower limit.

6. The exhaust gas recirculation apparatus for an engine according to claim 4, wherein the control unit is configured to limit calculation of the energization start correction value in a range of a predetermined upper limit to a predetermined lower limit.