Internal combustion engine EGR flow rate estimation apparatus and internal combustion engine control apparatus

Patent metadata

Field	Value
Publication number	US-10125703-B2
Application number	US-201414565465-A
Country	US
Kind code	B2
Filing date	Dec 10, 2014
Priority date	Sep 10, 2014
Publication date	Nov 13, 2018
Grant date	Nov 13, 2018

Abstract

Based on an internal EGR ratio and desired external and internal EGR ratios, an EGR valve opening degree is feedback-controlled based on a desired EGR ratio, calculated in such a way as to perform correction so that a total EGR ratio becomes constant, and an EGR effective opening area obtained through learning of the relationship between an EGR valve opening degree and an effective opening area; thus, a correct characteristic of EGR valve opening degree vs. effective opening area can be maintained and hence it is made possible to absorb variations, changes with time, and even environmental conditions, while making an EGR valve and an intake/exhaust VVT collaborate with each other; therefore, an EGR flow rate can accurately be estimated.

First claim

What is claimed is:

1. An internal combustion engine EGR flow rate estimation apparatus that estimates an EGR flow rate in an EGR flow path connecting an air-intake path at the downstream side of a throttle valve of an internal combustion engine and an exhaust path of the internal combustion engine, the internal combustion engine EGR flow rate estimation apparatus comprising:
the air-intake path for supplying air to the internal combustion engine;
the internal combustion engine;
the exhaust path of the internal combustion engine;
the EGR flow path;
an EGR valve configured to open or close the EGR flow path based on a calculated EGR valve opening degree so as to control an external EGR flow rate as an EGR flow rate in the EGR flow path; and
a processor storing instructions to implement:
an intake air flow rate calculator that calculates a flow rate of air taken into a cylinder of the internal combustion engine through the throttle valve of the internal combustion engine;
a volume efficiency correction coefficient calculator that calculates a volume efficiency correction coefficient, as a volume efficiency corresponding value which is an index for indicating an amount of air that flows into a cylinder of the internal combustion engine, based on valve timing control of at least one of an intake valve and an exhaust valve of the internal combustion engine;
a cylinder flow rate calculator that calculates a cylinder flow rate of air that flows from the air-intake path at the downstream side of the throttle valve into the cylinder, based on a pressure in the air-intake path and the calculated volume efficiency correction coefficient;
an internal EGR ratio estimator that estimates, based on the valve timing control, an internal EGR ratio which is the ratio of an internal EGR flow rate, as a flow rate of exhaust gas, of the internal combustion engine, that remains in the cylinder, to the intake air flow rate calculated by the intake air flow rate calculator;
a desired intake air flow rate calculator that calculates a desired intake air flow rate of the internal combustion engine, based on desired torque of the internal combustion engine;
a desired external/internal EGR ratio calculator that calculates a desired external EGR ratio and a desired internal EGR ratio, based on the desired intake air flow rate calculated by the desired intake air flow rate calculator and a rotation speed of the internal combustion engine;
a desired EGR ratio estimator that calculates a desired EGR ratio, based on the desired external EGR ratio and the desired internal EGR ratio estimated by the desired external/internal EGR ratio estimator and the internal EGR ratio estimated by the internal EGR ratio estimator;
an EGR flow rate calculator that calculates an EGR flow rate, based on the cylinder flow rate calculated by the cylinder flow rate calculator and the intake air flow rate calculated by the intake air flow rate calculator;
an EGR effective opening area calculator that calculates an effective opening area of the EGR valve corresponding to an EGR effective opening degree of the EGR valve, based on the EGR flow rate calculated by the EGR flow rate calculator;
an EGR effective opening area learning calculator that determines a relationship between a detected opening degree of the EGR valve based on an output of an EGR valve opening degree sensor that detects the opening degree of the EGR valve and the EGR effective opening area calculated by the EGR effective opening area calculator; and
an EGR valve opening degree calculator that calculates the calculated opening degree of the EGR valve and opens the EGR valve using the calculated EGR valve opening degree,

wherein the EGR valve opening degree calculator calculates the EGR valve calculated opening degree utilized in control of the internal combustion engine, based on the desired EGR ratio estimated by the desired EGR ratio estimator, the EGR effective opening area calculated by the EGR effective opening area calculator, and a learning value learned by the EGR effective opening area learning calculator.

2. The internal combustion engine EGR flow rate estimation apparatus according to claim 1 ,
wherein the desired external/internal EGR ratio estimator is configured in such a way that an intake air flow rate, a rotation speed of the internal combustion engine, an external EGR ratio, and an internal EGR ratio are preliminarily set in such a way that the preliminarily set external EGR ratio and internal EGR ratio are based on a rotation speed of the internal combustion engine and an intake air flow rate at a time when the internal combustion engine is operated,
wherein the desired EGR ratio estimator is configured in such a way that the desired EGR ratio is calculated by correcting the desired external EGR ratio, based on the difference between the desired internal EGR ratio and the real value of an internal EGR ratio, in such a way that the total EGR ratio, which is the total of an internal EGR ratio and an external EGR ratio, becomes constant, and
wherein the desired EGR ratio estimator calculates the desired EGR ratio in such a way that the total EGR ratio is calculated based on the desired external EGR ratio and the desired internal EGR ratio estimated by the desired external/internal EGR ratio estimator and then the desired external EGR ratio is corrected by use of the internal EGR ratio so that the total EGR ratio becomes constant.

3. The internal combustion engine EGR flow rate estimation apparatus according to claim 1 , comprising:
an inner-intake-path pressure sensor that is situated at the downstream side of the throttle valve and detects a pressure in the air-intake path connected with the EGR path;
an inner-exhaust-path temperature sensor that detects an temperature in the exhaust path connected with the EGR path;
an inner-exhaust-path pressure sensor that detects a pressure in the exhaust path connected with the EGR path;
an inner-exhaust-path sonic velocity calculator that calculates a sonic velocity in the exhaust path, based on a temperature in the exhaust path detected by the inner-exhaust-path temperature sensor;
an inner-exhaust-path density calculator that calculates a density in the exhaust path, based on a pressure in the exhaust path detected by the inner-exhaust-path pressure sensor and a temperature in the exhaust path detected by the inner-exhaust-path temperature sensor;
an EGR base effective opening area calculator that calculates an EGR base effective opening area from a preliminarily set EGR valve opening degree vs. EGR base effective opening area map; and
an effective opening area correction unit that corrects an EGR valve effective opening area utilized in controlling the internal combustion engine,
wherein the EGR effective opening area calculator is configured in such a way that an EGR effective opening area is calculated from the detected opening degree of the EGR valve, a pressure in the air-intake path, a pressure in the exhaust path, a sonic velocity in the exhaust path, an inner-exhaust-path density, and the EGR flow rate,
wherein the EGR effective opening area learning calculator is configured in such a way that the EGR effective opening area learning value is calculated based on an EGR effective opening area calculated by the EGR effective opening area calculator and an EGR base effective opening area calculated by the EGR base effective opening area calculator,
wherein the effective opening area correction unit is configured in such a way that an EGR valve effective opening area utilized in controlling the internal combustion engine is corrected based on an EGR effective opening area learning value calculated by the EGR effective opening area learning calculator, and
wherein the EGR valve opening degree calculator learns a relationship between an EGR effective opening ar

Assignees

• Mitsubishi Electric Corp

Inventors

• Watanuki Takuo
• Hagari Hideki
• Makino Tomokazu

Classifications

• F02M26/48

  EGR valve position sensors (details of the sensor installation in the valve housing F02M26/72) · CPC title

• F02D2200/0406

  Intake manifold pressure · CPC title

• F02D2200/0414

  Air temperature · CPC title

• F02D41/18

  by measuring intake air flow · CPC title

• F02D41/006

  using internal EGR (control of valve overlap for internal EGR F02D13/0261; arrangements for internal EGR F02M26/01) · CPC title