초록 ▼

The disclosure describes an engine system having liquid and gaseous fuel systems, each of which injects fuel directly into an engine cylinder. A controller monitors and controls engine operation in a normal mode, during which the engine produces rated power, and in a limp-home mode, which is used wh

The disclosure describes an engine system having liquid and gaseous fuel systems, each of which injects fuel directly into an engine cylinder. A controller monitors and controls engine operation in a normal mode, during which the engine produces rated power, and in a limp-home mode, which is used when an abnormal operating condition of the gaseous fuel system is present. During limp-home mode operation, the engine uses more liquid fuel and less or no gaseous fuel relative to the normal mode, and produces power that is less than rated power.

대표청구항 ▼

1. A direct injection gas engine system, comprising: an engine having at least one cylinder that forms a variable volume between a reciprocating piston, a bore, and a flame deck;a liquid fuel system that includes a liquid fuel rail in fluid communication with a liquid fuel injector, the liquid fuel

1. A direct injection gas engine system, comprising: an engine having at least one cylinder that forms a variable volume between a reciprocating piston, a bore, and a flame deck;a liquid fuel system that includes a liquid fuel rail in fluid communication with a liquid fuel injector, the liquid fuel injector configured to inject liquid fuel directly into the variable volume as an ignition source;a gaseous fuel system that includes a gaseous fuel injector, the gaseous fuel injector configured to inject gaseous fuel directly into the variable volume as a power source;a controller disposed to monitor and control operation of the engine in a normal mode or in a limp-home mode, the normal mode being present when abnormal operating conditions are absent, and the limp-home mode being present when the controller determines that abnormal operating conditions are present, such that: when operating in the normal mode, a normal amount of liquid fuel and a normal amount of gaseous fuel are injected into the cylinder to produce a rated engine power, andwhen operating in the limp-home mode, an amount of liquid fuel that is larger than the normal amount of liquid fuel and an amount of gaseous fuel that is less than the normal amount of gaseous fuel are injected into the cylinder to produce a limp-home engine power that is less than the rated power;wherein the liquid fuel system includes a liquid fuel pump configured to draw liquid fuel from a liquid fuel reservoir and provide pressurized liquid fuel to a liquid fuel rail that is fluidly connected to the liquid fuel injector, the pressurized liquid fuel being pressurized to a rail pressure;wherein the gaseous fuel system includes a cryogenic tank configured to store the gaseous fuel in a liquid state, and a gaseous fuel supply line in fluid communication with the gaseous fuel injector;wherein the gaseous fuel system further comprises a gaseous fuel pump configured to draw liquefied gaseous fuel from the cryogenic tank and provide compressed liquefied gaseous fuel to a heater, the heater configured to increase a temperature of the liquefied gaseous fuel; anda pressure control module disposed between the heater and the gaseous fuel supply line, the pressure control module configured to control a pressure of the gaseous fuel. 2. The engine system of claim 1, wherein the liquid fuel and gaseous fuel are sequentially injected into the cylinder. 3. The engine system of claim 1, wherein the pressure of the gaseous fuel and the rail pressure of the compressed liquid fuel are about equal when the engine system is operating in the normal mode. 4. The engine system of claim 1, further comprising at least one of: a gas state sensor disposed between the gaseous fuel supply line and the pressure control module, the gas state sensor configured to provide a rail state signal indicative of a state of the compressed liquid fuel to the controller;a fuel filter state sensor disposed between the fuel filter and the pressure control module, the fuel filter state sensor configured to provide a filter state signal indicative of a filtered gaseous fuel state to the controller;a heater state sensor disposed between the fuel filter and the heater, the heater state sensor configured to provide a heater state signal indicative of a gaseous fuel state to the controller;a liquid state sensor disposed at an outlet of the gaseous fuel pump and configured to provide a liquid state signal indicative of a compressed gaseous fuel state to the controller; anda level sensor associated with the cryogenic tank and configured to provide a level signal indicative of a level of the gaseous fuel in the liquid state within the cryogenic tank to the controller. 5. The engine system of claim 4, wherein the controller is configured to monitor one or more of the rail state, filter state, heater state, liquid state and level signals to determine the presence of abnormal operating conditions, and to shift engine operation from the normal mode to the limp-home mode when one or more abnormal operating conditions are present. 6. A failure mitigation system for a direct injection gas engine that uses a diesel pilot to ignite a directly injected gaseous fuel such as liquefied petroleum or natural gas that is stored in a cryogenic tank and is heated in a heater for use in an engine, the failure mitigation system operating in a controller associated with the DIG engine, comprising: at least one engine cylinder that forms a variable volume between a piston disposed within a bore, a portion of the bore, and a flame deck;a diesel fuel system that includes a diesel fuel rail in fluid communication with a diesel fuel injector, the diesel fuel injector configured to inject diesel fuel directly into the variable volume as an ignition source;a gaseous fuel system that includes a gaseous fuel injector, the gaseous fuel injector configured to inject gaseous fuel directly into the variable volume as a power source;wherein the controller is disposed to monitor and control operation of the engine in a normal mode or in a limp-home mode, the normal mode being present when abnormal operating conditions are absent, and the limp-home mode being present when the controller determines that abnormal operating conditions are present, such that: when operating in the normal mode, a normal amount of diesel fuel and a normal amount of gaseous fuel are injected into the cylinder to produce a rated engine power, andwhen operating in the limp-home mode, an amount of diesel fuel that is larger than the normal amount of diesel fuel and an amount of gaseous fuel that is less than the normal amount of gaseous fuel are injected into the cylinder to produce a limp-home engine power that is less than the rated power;wherein the gaseous fuel system further comprises a gaseous fuel pump configured to draw liquefied gaseous fuel from the cryogenic tank and provide compressed liquefied gaseous fuel to a heater, the heater configured to increase a temperature of the liquefied gaseous fuel such that the liquefied gaseous fuel approaches a supercritical gas state, and a fuel filter disposed to filter the gaseous fuel in the supercritical gas state; anda gaseous fuel supply line in fluid communication with the gaseous fuel injector, and a pressure control module disposed between the heater and the gaseous fuel supply line, the pressure control module configured to control a pressure of the gaseous fuel provided to the gaseous fuel injector. 7. The failure mitigation system of claim 6, wherein the diesel fuel system includes a diesel fuel pump configured to draw diesel fuel from a reservoir and provide pressurized diesel fuel to the diesel fuel rail that is fluidly connected to the diesel fuel injector, the pressurized diesel fuel being pressurized to a rail pressure. 8. The failure mitigation system of claim 6, wherein the pressure of the gaseous fuel and the rail pressure of the diesel fuel are about equal when the engine system is operating in the normal mode. 9. The engine system of claim 6, further comprising at least one of: a gas state sensor disposed between the gaseous fuel supply line and the pressure control module, the gas state sensor configured to provide a state signal indicative of a fuel state to the controller;a fuel filter state sensor disposed between the fuel filter and the pressure control module, the fuel filter state sensor configured to provide a filter state signal indicative of a state of filtered gaseous fuel to the controller;a heater state sensor disposed between the fuel filter and the heater, the heater state sensor configured to provide a heater state signal indicative of a gaseous fuel state pressure to the controller;a liquid state sensor disposed at an outlet of the gaseous fuel pump and configured to provide a liquid state signal indicative of a compressed gaseous fuel state to the controller; anda level sensor associated with the cryogenic tank and configured to provide a level signal indicative of a level of the gaseous fuel in the liquid state within the cryogenic tank to the controller. 10. The failure mitigation system of claim 9, wherein the controller is configured to monitor one or more of the state at the supply line, filter state, heater state, liquid state and level signals to determine the presence of abnormal operating conditions, and to shift engine operation from the normal mode to the limp-home mode when one or more abnormal operating conditions are present. 11. The failure mitigation system of claim 6, wherein the diesel fuel injector and the gaseous fuel injector are integrated into a single injector having first and second check valves, each of which corresponds to respective first and second actuators that are independently activatable, each of the first and second actuator being associated with a valve that, when activated, causes the first check valve corresponding to the first actuator or the second check valve corresponding to the second actuator to open such that diesel fuel is injected when the first check valve is open and gaseous fuel is injected when the second check valve is open. 12. A method for mitigating gaseous fuel system failures or abnormal operating conditions in a direct injection gas engine, comprising: operating a gaseous fuel supply system that includes a storage tank adapted to store a gaseous fuel in a cryogenically liquefied state, a gas pump adapted to draw gaseous fuel from the storage tank and compress it to produce compressed gaseous fuel, a heater adapted to increase an enthalpy of the compressed gaseous fuel, and a gaseous fuel supply line adapted to provide the compressed gaseous fuel;monitoring, in a controller, sensor signals indicative of operating conditions of the gaseous fuel supply, the sensor signals including at least one of a state signal, which is indicative of a state of the compressed gaseous fuel in the gaseous fuel supply line, a heater state signal, which is indicative of a gaseous fuel state at an outlet of the heater, a liquid state signal, which is indicative of a gaseous fuel state at an inlet of the heater, and a level signal, which is indicative of a level of the gaseous fuel in the cryogenically liquefied state within the storage tank;determining in the controller that an abnormal operating condition is present based on the monitoring of at least one of the rail state signal, the heater state signal, the liquid state signal and the level signal; andshifting engine operation by use of the controller from a normal mode to a limp-home mode when the abnormal operating condition is present;wherein, when operating in the normal mode, a normal amount of a liquid fuel and a normal amount of the gaseous fuel are injected into an engine cylinder to produce a rated engine power, andwhen operating in the limp-home mode, an amount of liquid fuel that is larger than the normal amount of liquid fuel and an amount of gaseous fuel that is less than the normal amount of gaseous fuel are injected into the engine cylinder to produce a limp-home engine power that is less than the rated power. 13. The method of claim 12, further comprising controlling the pressure of the compressed gaseous fuel at the outlet of the heater such that a controlled pressure of gaseous fuel is provided at the gaseous fuel supply line. 14. The method of claim 12, wherein shifting engine operation from the normal mode to the limp-home mode includes increasing a pressure of the liquid fuel and increasing an injection duration of a liquid fuel injector to compensate for the reduction in the amount of gaseous fuel injecting into the engine cylinder.