Control system for compression-ignition engine
First Claim
1. A control system for a compression-ignition engine, comprising:
- an engine having a combustion chamber formed by a cylinder, a piston and a cylinder head;
an injector attached to the engine and configured to supply fuel into the combustion chamber;
a spark plug disposed to be oriented into the combustion chamber;
an exhaust gas recirculation (EGR) device including an EGR passage through which exhaust gas discharged to an exhaust passage from the combustion chamber recirculates into the combustion chamber, and an EGR valve provided to the EGR passage and configured to adjust an external EGR ratio that is a ratio of the exhaust gas recirculated into the combustion chamber through the EGR passage to total gas in the combustion chamber;
an EGR controller configured to adjust an internal EGR ratio that is a ratio of residual burned gas to the total gas in the combustion chamber, the EGR controller adjusting the internal EGR ratio so that a compression start temperature of the combustion chamber rises as an engine load is reduced; and
a controller connected to the injector and the spark plug, and configured to output a control instruction to the injector and the spark plug, respectively, the controller including a processor configured to execute a combustion controlling module to output an ignition instruction to the spark plug so as to ignite at a given ignition timing after the internal EGR ratio adjustment, so that partial compression-ignition combustion in which a mixture gas combusts by flame propagation and then combusts by compression ignition is performed,wherein the combustion controlling module controls the EGR valve to increase the external EGR ratio as the engine load increases, within a first engine operating range where the partial compression-ignition combustion forms an air-fuel (A/F) lean environment in which an air-fuel ratio that is a ratio of air to fuel inside the combustion chamber is larger than a stoichiometric air-fuel ratio,wherein within a second engine load range where the engine load is higher than the first engine operating range, the combustion controlling module performs the partial compression-ignition combustion while forming a gas-fuel (G/F) lean environment in which a gas-fuel ratio that is a ratio of the total gas to fuel inside the combustion chamber is larger than the stoichiometric air-fuel ratio and the air-fuel ratio substantially matches the stoichiometric air-fuel ratio, andwherein the external EGR ratio in the second engine load range is larger than the external EGR ratio in the first engine load range.
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Accused Products
Abstract
A control system for a compression-ignition engine is provided, which includes an engine having a combustion chamber formed by a cylinder, a piston and a cylinder head, an injector, a spark plug, an exhaust gas recirculation (EGR) device configured to introduce into the combustion chamber a portion of burned gas generated inside the combustion chamber as EGR gas, an EGR controller configured to change an EGR ratio, the EGR controller changing the EGR ratio so that a compression start temperature of the combustion chamber rises as an engine load is reduced, and a controller connected to the injector and the spark plug to control them. The controller includes a processor configured to execute a combustion controlling module to output an instruction to the spark plug so as to ignite at an ignition timing after the EGR ratio adjustment so that partial compression-ignition combustion is performed.
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Citations
10 Claims
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1. A control system for a compression-ignition engine, comprising:
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an engine having a combustion chamber formed by a cylinder, a piston and a cylinder head; an injector attached to the engine and configured to supply fuel into the combustion chamber; a spark plug disposed to be oriented into the combustion chamber; an exhaust gas recirculation (EGR) device including an EGR passage through which exhaust gas discharged to an exhaust passage from the combustion chamber recirculates into the combustion chamber, and an EGR valve provided to the EGR passage and configured to adjust an external EGR ratio that is a ratio of the exhaust gas recirculated into the combustion chamber through the EGR passage to total gas in the combustion chamber; an EGR controller configured to adjust an internal EGR ratio that is a ratio of residual burned gas to the total gas in the combustion chamber, the EGR controller adjusting the internal EGR ratio so that a compression start temperature of the combustion chamber rises as an engine load is reduced; and a controller connected to the injector and the spark plug, and configured to output a control instruction to the injector and the spark plug, respectively, the controller including a processor configured to execute a combustion controlling module to output an ignition instruction to the spark plug so as to ignite at a given ignition timing after the internal EGR ratio adjustment, so that partial compression-ignition combustion in which a mixture gas combusts by flame propagation and then combusts by compression ignition is performed, wherein the combustion controlling module controls the EGR valve to increase the external EGR ratio as the engine load increases, within a first engine operating range where the partial compression-ignition combustion forms an air-fuel (A/F) lean environment in which an air-fuel ratio that is a ratio of air to fuel inside the combustion chamber is larger than a stoichiometric air-fuel ratio, wherein within a second engine load range where the engine load is higher than the first engine operating range, the combustion controlling module performs the partial compression-ignition combustion while forming a gas-fuel (G/F) lean environment in which a gas-fuel ratio that is a ratio of the total gas to fuel inside the combustion chamber is larger than the stoichiometric air-fuel ratio and the air-fuel ratio substantially matches the stoichiometric air-fuel ratio, and wherein the external EGR ratio in the second engine load range is larger than the external EGR ratio in the first engine load range. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A control system for a compression-ignition engine including an injector configured to supply fuel into a combustion chamber;
- a spark plug configured to ignite a mixture gas containing fuel supplied from the injector and air; and
an exhaust gas recirculation device including an EGR passage through which exhaust gas discharged to an exhaust passage from the combustion chamber recirculates into the combustion chamber, and an EGR valve provided to the EGR passage and configured to adjust an external EGR ratio that is a ratio of the exhaust gas recirculated into the combustion chamber through the EGR passage to total gas in the combustion chamber, the engine performing partial compression-ignition combustion including SI combustion performed by combusting a portion of the mixture gas through spark-ignition by the spark plug, followed by compression ignition (CI) combustion performed by causing the remaining mixture gas to self-ignite, the control system comprising;an EGR controller to adjust an internal EGR ratio that is a ratio of residual burned gas to the total gas in the combustion chamber; and a processor configured to execute a combustion controlling module to, during the partial compression-ignition combustion, adjust the internal EGR ratio by using the EGR controller so that a compression start temperature of the combustion chamber rises as an engine load is reduced, and cause the spark plug to perform spark-ignition at a given ignition timing so that the SI combustion of the mixture gas is performed followed by the CI combustion, wherein the combustion controlling module controls the EGR valve to increase the external EGR ratio as the engine load increases, within a first engine operating range where the partial compression-ignition combustion forms an air-fuel (A/F) lean environment in which an air-fuel ratio that is a ratio of air to fuel inside the combustion chamber is larger than a stoichiometric air-fuel ratio, wherein within a second engine load range where the engine load is higher than the first engine operating range, the combustion controlling module performs the partial compression-ignition combustion while forming a gas-fuel (G/F) lean environment in which a gas-fuel ratio that is a ratio of the total gas to fuel inside the combustion chamber is larger than the stoichiometric air-fuel ratio and the air-fuel ratio substantially matches the stoichiometric air-fuel ratio, and wherein the external EGR ratio in the second engine load range is larger than the external EGR ratio in the first engine load range.
- a spark plug configured to ignite a mixture gas containing fuel supplied from the injector and air; and
Specification