Internal combustion engine inner-cylinder pressure estimation apparatus

Patent metadata

Field	Value
Publication number	US-9494489-B2
Application number	US-201414177836-A
Country	US
Kind code	B2
Filing date	Feb 11, 2014
Priority date	Nov 15, 2013
Publication date	Nov 15, 2016
Grant date	Nov 15, 2016

Abstract

An internal combustion engine inner-cylinder pressure estimation apparatus includes a detection unit that detects an operation condition of an internal combustion engine, a calculation unit that calculates an ignition delay that is an interval from an ignition timing to a starting timing of heat generation by combustion, based on an operation condition detected by the detection unit, and a combustion velocity calculation unit that calculates a combustion velocity, based on the operation condition. There is simulated a phenomenon that after an ignition delay period following an ignition timing has elapsed, a flame generated at the gap portion of an ignition plug expands up to the inner-cylinder wall surface at the combustion velocity and in the shape of an ellipsoid whose center is the gap portion of the ignition plug.

First claim

What is claimed is:

1. An internal combustion engine inner-cylinder pressure estimation apparatus comprising:
an electronic control unit (ECU) configured to
detect an operation condition of an internal combustion engine;
calculate an ignition delay that is an interval from an ignition timing to a starting timing of heat generation by combustion, based on the detected operation condition;
calculate a combustion velocity, based on the operation condition; and
estimate an inner-cylinder pressure by:
simulating a flame surface area of a flame generated at a gap portion of an ignition plug after an ignition delay period following an ignition timing has elapsed, as a revolving ellipsoid having a center at the gap portion of the ignition plug and expanding to an inner-cylinder wall surface at the combustion velocity,
calculating the flame surface area based on a simulation result,
calculating respective inner-cylinder pressures of a combusted portion and a non-combusted portion based on the calculated flame surface area, the combusted portion and the non-combusted portion corresponding to an inside area and an outside area of the simulated flame surface area, respectively, and
estimating the inner-cylinder pressure based on the inner-cylinder pressures of the combusted portion and the non-combusted portion.

2. The internal combustion engine inner-cylinder pressure estimation apparatus according to claim 1 , wherein a heat generation rate is calculated based on a changing amount of the volume of the flame.

3. The internal combustion engine inner-cylinder pressure estimation apparatus according to claim 1 ,
wherein a heat generation rate is calculated based on a changing amount of the volume of the flame,
wherein an inner-cylinder temperature of the combusted portion is calculated based on a heat quantity calculated from the heat generation rate,
wherein an inner-cylinder pressure of the combusted portion is calculated based on the inner-cylinder temperature of the combusted portion, and
wherein the inner-cylinder pressure is estimated based on the inner-cylinder pressure of the non-combusted portion, the inner-cylinder pressure of the combusted portion, and a combustion rate.

4. The internal combustion engine inner-cylinder pressure estimation apparatus according to claim 2 , wherein the combustion velocity gradually decreases after the heat generation rate has reached the peak thereof.

5. The internal combustion engine inner-cylinder pressure estimation apparatus according to claim 3 , wherein the combustion rate is calculated based on the volume of the flame and an inner-cylinder volume.

6. The internal combustion engine inner-cylinder pressure estimation apparatus according to claim 1 , wherein the ECU is further configured to fit the combustion velocity with the ignition delay by:
calculating a tentative combustion rate by simulating a phenomenon, by use of an arbitrarily changeable tentative combustion velocity, that a flame expands in an ellipsoidal manner;
changing a tentative combustion velocity until a real combustion rate calculated from a preliminarily measured inner-cylinder pressure and the tentative combustion rate approximately coincide with each other and that derives, as a real combustion velocity, the tentative combustion velocity at a time when the real combustion rate and the tentative combustion rate approximately coincide with each other;
calculating, as a real ignition delay, a period that is after ignition and in which the real combustion velocity is zero; and
approximating the real combustion velocity and the real ignition delay, respectively.

7. The internal combustion engine inner-cylinder pressure estimation apparatus according to claim 1 , wherein the ECU is further configured to fit the combustion velocity with the ignition delay by:
calculating a tentative combustion rate by simulating a phenomenon, by use of an arbitrarily changeable tentative combustion velocity, that a flame expands in an ellipsoidal manner;
changing a tentative combustion velocity until a real combustion rate calculated from a preliminarily measured inner-cylinder pressure and the tentative combustion rate approximately coincide with each other and that derives, as a real combustion velocity, the tentative combustion velocity at a time when the real combustion rate and the tentative combustion rate approximately coincide with each other;
calculating, as a real ignition delay, a period that is after ignition and in which the real combustion velocity is zero; and
approximating the real combustion velocity and the real ignition delay, respectively, wherein with regard to an initial surge portion, of the real combustion velocity, that is caused by the fitting method, the ignition delay is corrected in such a way that when the combustion velocity is constant, the combustion amount remains the same.

Assignees

• Mitsubishi Electric Corp

Inventors

• Hagari Hideki

Classifications

• G01M15/08 Primary

  by monitoring pressure in cylinders · CPC title

• F02D35/028

  by determining the combustion timing or phasing · CPC title

• F02D35/024 Primary

  using an estimation · CPC title

• F02D35/026

  using an estimation · CPC title