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US 9,284,884 B2Granted
Trapped burned gas fraction control for opposed-piston engines with uniflow scavenging
AssigneeAchates Power, Inc.
InventorsNishit Nagar, Donovan M. Quimby
Life of this patent
Estimating the term…
Abstract
A trapped burned gas fraction is controlled in a two-stroke cycle opposed-piston engine with uniflow scavenging by adjusting an external EGR setpoint in real time. The adjusted setpoint is used to control EGR flow in the engine's air handling system.
Claims15
A uniflow-scavenged opposed-piston engine equipped with an air handling system, comprising:
- at least one cylinder with a bore, longitudinally-spaced exhaust and intake ports, and a pair of pistons disposed in opposition in the bore and operative to open and close the exhaust and intake ports during operation of the engine;
- a charge air channel to provide charge air to at least one intake port;
- an exhaust channel to receive exhaust gas from at least one exhaust port;
- an exhaust gas recirculation (EGR) loop having a loop input coupled to the exhaust channel and a loop output coupled to the charge air channel;
- and,
- a control mechanization operable to:
- determine a value of a trapped air handling parameter based on elements of combustion trapped in the cylinder by the last port of the cylinder to close during a cycle of engine operation and adjust the value of the trapped air handling parameter in response to a rate of EGR flow in the EGR loop;
- and
- adjust the rate of EGR flow in the EGR loop based on the adjusted value of the trapped air handling parameter.
6 more elements
A method of operating an opposed-piston engine, comprising:
- generating exhaust gas in at least one ported cylinder of the engine;
- transporting exhaust gas from an exhaust port of the ported cylinder through an exhaust channel;
- recirculating a portion of the exhaust gas from the exhaust channel;
- pressurizing fresh air;
- mixing recirculated exhaust gas with the pressurized fresh air to form charge air;
- pressurizing the charge air;
- providing the charge air to an intake port of the ported cylinder;
- determining a value of a trapped air handling parameter based on elements of combustion trapped in the cylinder by the last port of the cylinder to close during a cycle of engine operation;
- adjusting the value of the trapped air handling parameter in response to a rate of EGR flow in the EGR loop;
- and
- adjusting the rate of EGR flow in the EGR loop based on the adjusted value of the trapped air handling parameter.
8 more elements
A uniflow-scavenged opposed-piston engine, comprising:
- at least one cylinder with a bore, longitudinally-spaced exhaust and intake ports, and a pair of pistons disposed in opposition in the bore and operative to open and close the exhaust and intake ports during operation of the engine;
- a charge air channel to provide charge air to at least one intake port;
- an exhaust channel to receive exhaust gas from at least one exhaust port;
- an exhaust gas recirculation (EGR) loop having a loop input coupled to the exhaust channel and a loop output coupled to the charge air channel;
- and,
- a control mechanization operable to:
- determine a trapped burned gas fraction value for a current engine operating state based on elements of combustion trapped in the cylinder by the last port of the cylinder to close during a cycle of engine operation;
- determine a desired setpoint for EGR flow in the EGR loop for the trapped burned gas fraction value;
- compare the desired setpoint with an actual rate of EGR flow in the EGR loop;
- and,
- adjust the position of an EGR valve in the EGR loop based on the comparison.
8 more elements
Dependencies are inferred from the claim text.