Control device for compression ignition engine

Patent metadata

Field	Value
Publication number	US-10907568-B2
Application number	US-201916713418-A
Country	US
Kind code	B2
Filing date	Dec 13, 2019
Priority date	Dec 25, 2018
Publication date	Feb 2, 2021
Grant date	Feb 2, 2021

Abstract

A control device for a compression ignition engine is provided, which causes an injector to perform a pre-injection and a main injection, sets fuel injection timings of these injections so that an interval between a first peak of a heat release rate resulting from the combustion of fuel injected by the pre-injection and a second peak of the heat release rate resulting from the combustion of fuel injected by the main injection becomes an interval to make pressure waves caused by these combustions cancel each other out, and when an increase of an oxygen concentration of intake air supplied to a combustion chamber is detected, controls the injector to reduce the injection amount and retard the injection timing of the pre-injection compared with a case where the concentration increase is not detected under a condition that engine load and speed are the same.

First claim

What is claimed is:

1. A control device for a compression ignition engine causing fuel injected into a combustion chamber from an injector to combust by compression ignition, comprising:
an intake O 2 sensor configured to acquire an oxygen concentration of intake air supplied to the combustion chamber; and
a processor configured to execute a fuel injection controlling module to control an injection amount and an injection timing of the fuel by the injector,
wherein the fuel injection controlling module causes the injector to perform a pre-injection in which fuel is injected at an advancing side of a compression top dead center, and a main injection in which fuel is injected during combustion of the fuel injected by the pre-injection,
wherein the fuel injection controlling module sets the fuel injection timings of the pre-injection and the main injection so that an interval between a first peak of a heat release rate resulting from the combustion of the fuel injected by the pre-injection and a second peak of the heat release rate resulting from the combustion of the fuel injected by the main injection becomes an interval to make pressure waves caused by the combustions of the fuel of the pre-injection and the main injection cancel each other out, and
wherein when an increase of the oxygen concentration is detected by the intake O 2 sensor, the fuel injection controlling module controls the injector to reduce the injection amount of the pre-injection and retard the injection timing of the pre-injection compared with a case where the increase of the oxygen concentration is not detected, under a condition that an engine load and an engine speed are the same.

2. The control device of claim 1 , wherein when the increase of the oxygen concentration is detected, the fuel injection controlling module estimates an advanced deviation that is an amount by which the occurring timing of the first peak is shifted to the advancing side from a target timing due to the increase of the oxygen concentration, and sets a decreasing amount of the injection amount of the pre-injection so that the occurring timing of the first peak is retarded more than the estimated advanced deviation.

3. The control device of claim 2 , wherein when the increase of the oxygen concentration is detected, the fuel injection controlling module estimates a cutback deviation that is an amount by which a height of the first peak is reduced from a target height due to the injection amount of the pre-injection being decreased by the set decreasing amount, and sets a retarding amount of the injection timing of the pre-injection so that the height of the first peak increases by an amount corresponding to the estimated cutback deviation.

4. The control device of claim 1 ,
wherein the fuel injection timing of the pre-injection is set at a timing advanced from the compression top dead center by a given amount so that the fuel injected by the pre-injection carries out premixed compression ignition combustion,
wherein an estimation to estimate a heat-release characteristic is performed based on setting values of the injection timing of the pre-injection and the injection amount of the pre-injection, and
wherein the main injection is started during a combustion period of the fuel injected by the pre-injection and at the retarding side of a crank angle at which the first peak estimated by the estimation occurs so that the fuel injected by the main injection carries out diffuse combustion.

5. A control device for a compression ignition engine causing fuel injected into a combustion chamber from an injector to combust by compression ignition, comprising:
an intake O 2 sensor configured to acquire an oxygen concentration of intake air supplied to the combustion chamber; and
a processor configured to execute a fuel injection controlling module to control an injection amount and an injection timing of the fuel by the injector,
wherein the fuel injection controlling module causes the injector to perform a pre-injection in which fuel is injected at an advancing side of a compression top dead center, and a main injection in which fuel is injected during combustion of the fuel injected by the pre-injection,
wherein the fuel injection controlling module sets fuel injection timings of the pre-injection and the main injection so that an interval between a first peak of heat release rate resulting from the combustion of the fuel injected by the pre-injection and a second peak of the heat release rate resulting from the combustion of fuel injected by the main injection becomes an interval to make pressure waves caused by the combustion of the fuel of the pre-injection and the main injection cancel each other out, and
wherein when a decrease of the oxygen concentration is detected by the intake O 2 sensor, the fuel injection controlling module controls the injector to increase the injection amount of the pre-injection and advance the injection timing of the pre-injection compared with a case where the decrease of the oxygen concentration is not detected, under a condition that an engine load and an engine speed are the same.

6. The control device of claim 5 , wherein when the decrease of the oxygen concentration is detected, the fuel injection controlling module estimates a retarded deviation that is an amount by which the occurring timing of the first peak is shifted to a retarding side from a target timing due to the decrease of the oxygen concentration, and sets an increasing amount of the injection amount of the pre-injection so that the occurring timing of the first peak is advanced more than the estimated retarded deviation.

7. The control device of claim 6 , wherein when the decrease of the oxygen concentration is detected, the fuel injection controlling module estimates an extended deviation that is an amount by which a height of the first peak is increased from a target height due to the injection amount of the pre-injection being increased by the set increasing amount, and sets an advancing amount of the injection timing of the pre-injection so that the height of the first peak decreases by an amount corresponding to the estimated extended deviation.

8. The control device of claim 7 , wherein the fuel injection controlling module performs a plurality of divided injections of the pre-injection when the advancing amount of the injection timing of the pre-injection is calculated as a large value so that the pre-injection is started at the advancing side of a given crank angle.

Assignees

• Mazda Motor

Inventors

• MATSUO Takeru
• Kakuda Yoshie
• Kim Sangkyu
• Shimo Daisuke

Classifications

• F02D41/144

  Sensor in intake manifold · CPC title

• F02B1/14

  Methods of operating · CPC title

• F02D2200/04

  Engine intake system parameters · CPC title

• F02D41/403

  with pilot injections · CPC title

• F02D41/1454

  the characteristics being an oxygen content or concentration or the air-fuel ratio · CPC title