EP-4735752-A1 - APPARATUS AND METHOD FOR SUPPLYING GASEOUS FUEL TO AND OPERATING AN INTERNAL COMBUSTION ENGINE

Abstract

An apparatus for supplying a gaseous fuel and operating an internal combustion engine includes a supply storing the gaseous fuel as a compressed gas; a compressor selectively pressurizing the gaseous fuel received from the supply; a pressure regulator receiving the gaseous fuel selectively from the supply or from the compressor; a gaseous-fuel rail fluidly receiving the gaseous fuel from the pressure regulator; an in-cylinder injector receiving the gaseous fuel from the gaseous-fuel rail and directly introducing the gaseous fuel into a combustion chamber; the in-cylinder injector commanded in a first operating mode when the gaseous-fuel rail pressure is equal to or greater than a desired injection pressure; and the in-cylinder injector commanded in a second operating mode when the gaseous-fuel rail pressure is less than the desired injection pressure.

Inventors

• HUANG, JIAN
• POST, ADRIAN

Assignees

• Cespira Canada Limited Partnership

Dates

Publication Date

20260506

Application Date

20240626

Claims (20)

1. 1. An apparatus for supplying a gaseous fuel to and operating an internal combustion engine comprising: a first supply of the gaseous fuel storing the gaseous fuel as a compressed gas at a first supply pressure; a compressor selectively pressurizing the gaseous fuel fluidly received from the first supply to a pressurized pressure; a pressure regulator fluidly receiving the gaseous fuel selectively from the first supply at the first supply pressure or from the compressor at the pressurized pressure and fluidly providing the gaseous fuel at a delivery pressure; a gaseous-fuel rail fluidly receiving the gaseous fuel from the pressure regulator; an in-cylinder injector fluidly receiving the gaseous fuel from the gaseous-fuel rail and configured to directly introduce the gaseous fuel into a combustion chamber of the internal combustion engine, the in-cylinder injector injecting the gaseous fuel at a gaseous-fuel rail pressure (PGFR); a controller operatively connected with the in-cylinder injector and programmed to command the in-cylinder injector in a first operating mode when the gaseous-fuel rail pressure (PGFR) is equal to or greater than a desired injection pressure; and command the in-cylinder injector in a second operating mode when the gaseous- fuel rail pressure (PGFR) is less than the desired injection pressure; wherein in the first operating mode the pressure regulator fluidly receives the gaseous fuel from the first supply when the first supply pressure is greater than or equal to the desired injection pressure, and from the compressor when the first supply pressure is less than the desired injection pressure, in the first operating mode both the first supply and the compressor can deliver a demanded mass flow rate of the gaseous fuel by the internal combustion engine whereby the gaseous-fuel rail pressure (PGFR) is equal to the desired injection pressure, and in the second operating mode the first supply pressure is less than the desired injection pressure such that the pressure regulator fluidly receives the gaseous fuel from the compressor, in the second operating mode the demanded mass flow rate of the gaseous fuel is greater than a mass flow rate of the gaseous fuel delivered by the compressor whereby the gaseous-fuel rail pressure (PGFR) is less than the desired injection pressure.
2. 2. The apparatus as claimed in claim 1, wherein the gaseous fuel bums in a diffusion combustion mode in the first and second operating modes.
3. 3. The apparatus as claimed in claim 1, wherein a start of injection timing is earlier in a compression stroke and an injection duration is greater in the second operating mode compared to the first operating mode for a commanded injection mass.
4. 4. The apparatus as claimed in claim 1, wherein the internal combustion engine can operate at a maximum rated power in the first and second operating modes.
5. 5. The apparatus as claimed in claim 1, wherein in the first operating mode the gaseous-fuel rail pressure (PGFR) equals the desired injection pressure for both a low-power demand and a high- power demand of the internal combustion engine.
6. 6. The apparatus as claimed in claim 1, wherein the pressure regulator fluidly receives the gaseous fuel from the first supply in the second operating mode when the first supply pressure is less than the desired injection pressure and greater than or equal to a parasitic threshold pressure (PPT).
7. 7. The apparatus as claimed in claim 6, wherein the parasitic threshold pressure (PPT) is in a range of 150 to 300 bar.
8. 8. The apparatus as claimed in claim 1, wherein in the second operating mode the pressure regulator fluidly provides the gaseous fuel to the gaseous-fuel rail at an unregulated pressure since the mass flow rate of the gaseous fuel from the compressor is less than the demanded mass flow rate of the gaseous fuel by the internal combustion engine.
9. 9. The apparatus as claimed in claim 8, wherein in the second operating mode the gaseous-fuel rail pressure (PGFR) continues to decrease further below the desired injection pressure after each injection by the in-cylinder injector.
10. 10. The apparatus as claimed in claim 1, wherein the controller is further programmed to command the in-cylinder injector to switch from the second operating mode to a third operating mode when the gaseous-fuel rail pressure (PGFR) is less than a mid-cycle direct injection threshold pressure (PMCDI-T), wherein in the third operating mode the pressure regulator fluidly receives the gaseous fuel from the compressor and the demanded mass flow rate of the gaseous fuel by the internal combustion engine is greater than the mass flow rate of the gaseous fuel delivered by the compressor, the gaseous fuel bums in a partially premixed combustion mode in the third operating mode, a start of injection timing is earlier in a compression stroke and an injection duration is greater in the third operating mode compared to the second operating mode for a commanded injection mass, and the internal combustion engine can operate at a maximum rated power in the third operating mode.
11. 11. The apparatus as claimed in claim 10, wherein the first operating mode is commanded when the first supply pressure is greater than or equal to the desired injection pressure or when the first supply pressure is less than a parasitic threshold pressure (PPT) and greater than or equal to a compressor threshold pressure (PCT); the second operating mode is commanded when the first supply pressure is less than the desired injection pressure and greater than or equal to the parasitic threshold pressure (PPT), or when the first supply pressure is less than the compressor threshold pressure (PCT) and when the gaseous-fuel rail pressure (PGFR) is greater than or equal to the mid-cycle direct injection threshold pressure (PMCDI-T), and wherein the pressure regulator fluidly receives the gaseous fuel from the first supply bypassing the compressor in the second operating mode when the first supply pressure is less than the desired injection pressure and greater than or equal to the parasitic threshold pressure (PPT); and the third operating mode is commanded when the gaseous-fuel rail pressure (PGFR) is less than the mid-cycle direct injection threshold pressure (PMCDI-T).
12. 12. The apparatus as claimed in claim 11, wherein the compressor threshold pressure (PCT) is less than or equal to 350 bar and greater than or equal to 100 bar.
13. 13. The apparatus as claimed in claim 11, wherein the mid-cycle direct injection threshold pressure (PMCDI-T) is 35 bar to 45 bar above a peak cylinder pressure.
14. 14. The apparatus as claimed in claim 1, further comprising a bypass valve configured to fluidly communicate the gaseous fuel around the pressure regulator when the bypass valve is in an open position, the controller is further programmed to, when the first supply pressure is greater than the desired injection pressure, command the bypass valve to the open position such that the in-cylinder injector receives the gaseous fuel from the first supply at the first supply pressure; and command the in-cylinder injector in a fourth operating mode; wherein the gaseous fuel bums in a diffusion combustion mode in the fourth operating mode, a start of injection timing is later in a compression stroke and an injection duration is smaller in the fourth operating mode compared to the first operating mode for a commanded injection mass, and the internal combustion engine can operate at a maximum rated power in the fourth operating mode.
15. 15. The apparatus as claimed in claim 1, wherein the desired injection pressure is in a range of 200 to 400 bar.
16. 16. The apparatus as claimed in claim 1, further comprising a second supply of the gaseous fuel storing the gaseous fuel as a compressed gas at a second supply pressure; wherein the pressure regulator and the compressor fluidly receive the gaseous fuel selectively from the first supply or the second fuel supply.
17. 17. The apparatus as claimed in claim 16, wherein when the first supply is fluidly supplying the gaseous fuel to the in-cylinder injector, the first supply pressure is less than the desired injection pressure and the second supply pressure is greater than the desired injection pressure, and the gaseous-fuel rail pressure (PGFR) drops below the desired injection pressure in the first operating mode, then the controller is programmed to command the pressure regulator to fluidly receive the gaseous fuel from the second supply.
18. 18. The apparatus as claimed in claim 1, wherein the internal combustion engine operates at a first power demand and at a second power demand greater than the first power demand, the desired injection pressure at a first value in the first power demand and at a second value in the second power demand, the second value greater than the first value, when the internal combustion engine switches from operating with the first power demand to the second power demand, the gaseous-fuel rail pressure (PGFR) increases from the first value to the second value, when the gaseous-fuel rail pressure (PGFR) decreases below the second value of the desired injection pressure while operating at the second power demand, the internal combustion engine switches from the first operating mode to the second operating mode.
19. 19. The apparatus as claimed in claim 1, wherein the internal combustion engine operates at a first power demand and at a second power demand greater than the first power demand, the desired injection pressure at a first value in the first power demand and at a second value in the second power demand, the second value greater than the first value, when the internal combustion engine switches from operating at the second power demand in the second operating mode to the first power demand, the gaseous-fuel rail pressure (PGFR) decreases to the first value and the internal combustion engine switches to the first operating mode.
20. 20. The apparatus as claimed in any one of claims 1-19, wherein a start of injection timing and an injection duration are stored in one or more arrays indexed by the gaseous-fuel rail pressure (PGFR) and the commanded injection mass.

Description

APPARATUS AND METHOD FOR SUPPLYING GASEOUS FUEL TO AND OPERATING AN INTERNAL COMBUSTION ENGINE Technical Field [0001] The present application relates to an apparatus and method for supplying gaseous fuel to and operating an internal combustion engine, and in particular to applications employing a gaseous fuel stored as a compressed gas. Background [0002] Internal combustion engines that are fueled with gaseous fuels stored in the gas or supercritical state in pressurized storage tanks, such as compressed hydrogen (CH2) and compressed natural gas (CNG), can employ in-cylinder injectors to directly introduce the gaseous fuel into combustion chambers of the engine after intake valves close to increase engine power. Engine efficiency also increases when the gaseous fuel is injected late in a compression cycle of the engine such that the gaseous fuel bums in a diffusion combustion mode in what is known as a Diesel-cycle, where the compression ratio can be increased without the risk of premature ignition (knock) compared to when the gaseous fuel is injected early during the compression stroke where the gaseous fuel bums in a premixed combustion mode. In the Diesel-cycle there is a desired value of an injection pressure of the gaseous fuel that is characterized by an optimal or near to optimal efficiency that is capable for the engine. That is, as the rail pressure increases above the desired injection pressure the engine efficiency only marginally increases, whereas as the rail pressure decreases below the desired injection pressure the engine efficiency substantially decreases. The desired injection pressure can be a function of the engine load and engine speed. [0003] When the storage tanks are refilled, they are typically pressurized to a pressure of 350 bar or 700 bar, although other pressures are contemplated. In an exemplary embodiment the desired injection pressure is around 300 bar. As the gaseous fuel is consumed by the engine the pressure in the storage tanks decreases, and as the storage tank pressure drops below the desired injection pressure, a compressor can be employed to pressurize the gaseous fuel to the desired injection pressure. Even though the compressor is a parasitic load on the engine, it can increase the overall engine efficiency by pressurizing the gaseous fuel to the desired injection pressure. As the storage tank pressure continues to decrease, the parasitic load of the compressor continues to increase since more work is required to compress the gaseous fuel to the desired injection pressure. Eventually the energetic cost of the parasitic load of the compressor is greater than the improvements in engine efficiency by injecting at the desired injection pressure. Additionally, or alternatively, eventually the storage tank pressure drops to a value where the compressor is either incapable of pressurizing the gaseous fuel to the desired injection pressure (to a pressure ratio of the compressor) or is incapable of providing a demanded mass flow rate of the gaseous fuel to the engine. [0004] The size of the compressor also influences the operation of the engine. A larger compressor can provide a mass flow rate of the gaseous fuel at the desired injection pressure required by the engine to operate at maximum rated power at lower values of storage tank pressure compared to a smaller compressor. However, the larger compressor is typically a larger parasitic load on the engine compared to the smaller compressor for storage tank pressures within a range below and up to the desired injection pressure. [0005] Two or more injection pressures can be used for distinct parts of the engine map to reduce the losses from the parasitic load of the compressor, since the optimal injection pressure is also a function of engine load. For example, at lower engine loads a first pressure regulator can be employed to provide a lower injection pressure and a second pressure regulator can be used to provide a higher injection pressure at higher engine loads, whereby during the lower engine loads the storage tank pressure is increased to the lower injection pressure and the work required from the compressor to pressurize to the lower injection pressure is reduced compared to pressurizing to the higher injection pressure. Instead of different pressure regulators, a variable pressure regulator can also be employed to provide two or more regulated pressures. These solutions increase the cost of the engine system through increased component count and fuel system complexity. [0006] The state of the art is lacking in techniques for supplying gaseous fuel to and operating an internal combustion engine. The present apparatus and method provide a technique for improving the supply of gaseous fuel to and operating an internal combustion engine. Summary [0007] An improved apparatus for supplying a gaseous fuel to and operating an internal combustion engine includes a first supply of the gaseous fuel storing the gaseous fuel