Control system for compression-ignition engine

Patent metadata

Field	Value
Publication number	US-10895208-B2
Application number	US-201816055908-A
Country	US
Kind code	B2
Filing date	Aug 6, 2018
Priority date	Aug 24, 2017
Publication date	Jan 19, 2021
Grant date	Jan 19, 2021

Abstract

A control system for a compression-ignition engine is provided, which includes an engine configured to combust a mixture gas inside a combustion chamber by compression ignition, a fuel injector attached to the engine, a state function adjusting part attached to the engine and configured to adjust at least introduction of fresh air into the combustion chamber, a three-way catalyst provided in an exhaust passage of the engine, a wall temperature acquiring part configured to acquire a parameter related to a temperature of a wall of the combustion chamber, and a controller. A swirl flow is generated inside the combustion chamber to circle along the wall. When the wall temperature of the combustion chamber is below a given wall temperature, the controller sets an air-fuel ratio of the mixture gas substantially to a stoichiometric air-fuel ratio so as to remain within a purification window of the three-way catalyst.

First claim

What is claimed is:

1. A control system comprising:
a compression-ignition engine having a combustion chamber formed by a cylinder, a piston, and a cylinder head and configured to perform SPCCI (SPark Controlled Compression Ignition) combustion, in which spark ignition (SI) combustion and compression ignition combustion are combined;
a fuel injection valve attached to the engine;
a spark plug disposed to be oriented into the combustion chamber and configured to perform ignition;
an air-fuel ratio controller configured to adjust an air-fuel ratio of mixture gas inside the combustion chamber;
a three-way catalyst provided in an exhaust passage of the engine;
a temperature sensor configured to detect a parameter related to a temperature of the combustion chamber; and
a controller connected to the fuel injection valve, the air-fuel ratio controller, the spark plug, and the temperature sensor and configured to output a control signal to the air-fuel ratio controller upon reception of a detection signal from the temperature sensor,
wherein the controller includes:
a processor configured to execute:
a temperature determining module configured to determine whether the temperature of the combustion chamber is at or above a given temperature based on an output value of the temperature sensor;
an air-fuel ratio controlling module configured, when the temperature of the combustion chamber is determined to be below the given temperature at an engine load, to output the control signal to the air-fuel ratio controller to set the air-fuel ratio of the mixture gas to a stoichiometric air-fuel ratio and, when the temperature of the combustion chamber is determined to be above the given temperature at the engine load, to output the control signal to the air-fuel ratio controller to set the air-fuel ratio of the mixture gas leaner than the stoichiometric air-fuel ratio; and
a spark plug controlling module configured to output a control signal to the spark plug to perform the ignition at a given ignition timing so that the mixture gas starts combustion by flame propagation and then unburned mixture gas self-ignites, the given ignition timing being stored in an ignition timing memory,

wherein the controller controls the spark plug to perform SPCCI combustion so as to ignite the mixture gas at a first given timing so that the ignited mixture gas starts propagating flame along a wall of the combustion chamber by a swirl flow, and then unburned mixture gas is compressed to ignite at a second given timing,
wherein the controller comprises the air-fuel ratio controller,
wherein the parameter related to the temperature of the combustion chamber is an intake-air-temperature related value,
wherein the controller has a first operating range map defining a flame propagation combustion in which self-ignition does not occur from a lowest load to a highest load of the engine, a second operating range map defining self-ignition combustion in which the air-fuel ratio is at the stoichiometric air-fuel ratio from the lowest load to the highest load of the engine, and a third operating range map defining self-ignition combustion in which the air-fuel ratio is leaner than the stoichiometric air-fuel ratio from the lowest load to a given high load of the engine, and self-ignition combustion in which the air-fuel ratio is at the stoichiometric air-fuel ratio from the given high load to the highest load of the engine, and
wherein the controller further includes an operating range map selecting module configured to select the first operating range map when the intake-air-temperature related value is below a first low intake air temperature, the second operating range map when the intake-air-temperature related value is at or above the first low intake air temperature and below a second intake air temperature higher than the first low intake air temperature, and the third operating range map when the intake-air-temperature related value is at or above the second intake air temperature.

2. The control system of claim 1 , wherein the controller sets G/F as an index relating to a mass ratio between all gas and fuel inside the combustion chamber, to 18 to 50.

3. The control system of claim 1 , further comprising a swirl control valve configured to generate the swirl flow inside the combustion chamber,
wherein the controller controls the swirl control valve to adjust a state inside the combustion chamber at an ignition timing to have a swirl ratio of 2 to 6.

4. The control system of claim 1 , wherein the spark plug is disposed at a position of a ceiling surface of the combustion chamber, away from a center axis of the cylinder of the engine.

5. A control system comprising:
a compression-ignition engine having a combustion chamber formed by a cylinder, a piston, and a cylinder head and configured to perform SPCCI (SPark Controlled Compression Ignition) combustion, in which spark ignition (SI) combustion and compression ignition combustion are combined;
a fuel injection valve attached to the engine;
a spark plug disposed to be oriented into the combustion chamber and configured to perform ignition;
an air-fuel ratio controller configured to adjust an air-fuel ratio of mixture gas inside the combustion chamber;
a three-way catalyst provided in an exhaust passage of the engine;
a temperature sensor configured to detect a parameter related to a temperature of the combustion chamber; and
a controller connected to the fuel injection valve, the air-fuel ratio controller, the spark plug, and the temperature sensor and configured to output a control signal to the air-fuel ratio controller upon reception of a detection signal from the temperature sensor,
wherein the controller includes:
a processor configured to execute:
a temperature determining module configured to determine whether the temperature of the combustion chamber is at or above a given temperature based on an output value of the temperature sensor;
an air-fuel ratio controlling module configured, when the temperature of the combustion chamber is determined to be below the given temperature at an engine load, to output the control signal to the air-fuel ratio controller to set the air-fuel ratio of the mixture gas to a stoichiometric air-fuel ratio and, when the temperature of the combustion chamber is determined to be above the given temperature at the engine load, to output the control signal to the air-fuel ratio controller to set the air-fuel ratio of the mixture gas leaner than the stoichiometric air-fuel ratio; and
a spark plug controlling module configured to output a control signal to the spark plug to perform the ignition at a given ignition timing to perform SPCCI combustion so that the mixture gas starts combustion by flame propagation and then unburned mixture gas self-ignites, the given ignition timing being stored in an ignition timing memory,

wherein the parameter related to the temperature of the combustion chamber is a combustion-chamber-wall-temperature related value,
wherein the controller has a first operating range map defining flame propagation combustion in which self-ignition does not occur from a lowest load to a highest load of the engine, a second operating range map defining self-ignition combustion in which the air-fuel ratio is at the stoichiometric air-fuel ratio from the lowest load to the highest load of the engine, and a third operating range map defining self-ignition combustion in which the air-fuel ratio is leaner than the stoichiometric air-fuel ratio from the lowest load to a given high load of the engine, and self-ignition combustion in which the air-fuel ratio is at the stoichiometric air-fuel ratio from the given high load to the highest load of the engine,
wherein the controller further includes an operating range map selecting module confi

Assignees

• Mazda Motor

Inventors

• Inoue Atsushi
• SUEOKA Masanari
• Matsumoto Kota
• Maruyama Keiji

Classifications

• Y02T10/12

  Improving ICE efficiencies · CPC title

• F02B23/0624

  Swirl flow · CPC title

• F02D35/025

  by determining temperatures inside the cylinder, e.g. combustion temperatures · CPC title

• F02D2041/0015

  for engines with means for controlling swirl or tumble flow, e.g. by using swirl valves · CPC title

• F02D41/3041

  with means for triggering compression ignition, e.g. spark plug · CPC title