PROCESS FOR USE WITH DUAL-FUEL SYSTEMS

• US 20070125321A1
• Filed: 02/06/2007
• Published: 06/07/2007
• Est. Priority Date: 03/10/2004
• Status: Active Grant

• Current Assignee: TGI, Inc. (Platina Energy Group, Inc.)
• Original Assignee: TGI, Inc. (Platina Energy Group, Inc.)
• Inventors: Ritter, Gregory
• Granted Patent: US 7,387,091 B2
• Time in Patent Office: Days
• US Class Current: 123/27.GE
• CPC Class Codes: F02B 23/0621 Squish flow
• CPC Class Codes: F02B 29/0418 the intake air cooler having a bypass or multiple flow paths within the heat exchanger to vary the effective heat transfer surface
• CPC Class Codes: F02D 15/04 by alteration of volume of compression space without changing piston stroke
• CPC Class Codes: F02D 19/023 to adjust the fuel mass or volume flow
• CPC Class Codes: F02D 19/0631 by estimation, i.e. without using direct measurements of a corresponding sensor
• CPC Class Codes: F02D 19/066 Retrofit of secondary fuel supply systems; Conversion of engines to operate on multiple fuels
• CPC Class Codes: F02D 19/105 operating in a special mode, e.g. in a liquid fuel only mode for starting
• CPC Class Codes: F02M 21/0239 Pressure or flow regulators therefor
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies
• CPC Class Codes: Y02T 10/30 Use of alternative fuels, e.g. biofuels

Abstract

A system and method is provided to reduce the occurrence of engine knock for engines that utilize a dual-fuel fumigation system. Typically, dual fuel systems inject a gaseous-fuel flow into the air intake stream of a diesel engine. This results in more complete combustion within the engine as well as reduced diesel fuel usage. Such dual fuel systems are susceptible to engine knocking due to premature detonation of the gaseous fuel air intake mixture that is often caused by sudden changes to the operating conditions of the engine. The present system utilizes a knock sensor to identify early stages of such engine knocking. To eliminate such engine knocking conditions, the system temporarily interrupts the gaseous fuel flow to resume operation in full diesel mode. The gaseous fuel flow is then reestablished based on the present operating conditions of the engine.

Claims

1. A gaseous-fuel fumigation system for use with a diesel engine, comprising:

a first valve disposable in a flow path between a gaseous-fuel supply and an air intake stream of a diesel engine, the first valve being operative to regulate a flow volume of a gaseous-fuel through the flow path;

a knock sensor operative to monitor a motion level of said diesel engine and generate an output signal indicative of said motion level; and

a controller operative to;

receive the output signal from the knock sensor;

compare said output signal to at least a first threshold value; and

upon said output signal exceeding said first threshold value, generate control signals operative to move said first valve between an current open position defining a first gaseous-fuel flow volume, a substantially closed position defining a second gaseous-fuel flow volume, and a reopened position defining a third gaseous-fuel flow volume.

2. The system of claim 1, wherein resulting movement of said valve from said current open position to said substantially closed position and to said reopened position is substantially continuous.

3. The system of claim 1, wherein said second flow volume is a zero gaseous-fuel flow volume.

4. The system of claim 1, wherein said first gaseous-fuel flow volume and said third gaseous-fuel flow volume are different.

5. The system of claim 1, further comprising:

an oxygen sensor operative to generate a oxygen content signal indicative of an oxygen content of an exhaust stream of the diesel engine.

6. The system of claim 5, wherein said controller is further operative to:

receive said oxygen content signal from said oxygen sensor; and

generate a control signal operative to move said first valve between said substantially closed position and said reopened position, wherein said third gaseous-fuel flow volume associated with said reopened position is based at least in part on said oxygen content signal.

7. The system of claim 1, wherein said knock sensor comprises a piezoelectric device.

8. The system of claim 1, further comprising:

a second valve disposed in the flow path between the gaseous-fuel supply and the air intake stream of the diesel engine, the second valve being operative to regulate the flow volume of a gaseous-fuel through the flow path based on a load level associated with the engine.

9. The system of claim 8, wherein said first and second valves are disposed in series.

10. The system of claim 8, wherein said second valve regulates the flow volume of gaseous-fuel in relation to a boost pressure associated with a turbocharger attached to the engine.

11. The system of claim 10, wherein the second valve is operated by the boost pressure associated with the turbocharger.

12. The system of claim 1, further comprising:

a memory structure associated with said controller, wherein said memory structure is operative to store at least one predetermined threshold value.

13. A method for use with gaseous-fuel fumigation system attached to a diesel engine, comprising:

establishing a gaseous-fuel flow through a first valve disposed between a gaseous-fuel supply and an air intake stream of a diesel engine, wherein said first valve is operative for regulating a volume said gaseous-fuel flow;

monitoring a motion level of said engine;

upon said motion level exceeding at least one threshold value, substantially closing and reopening said first valve, wherein said gaseous fuel flow to said air intake is temporarily interrupted.

14. The method of claim 13, wherein said first valve is substantially closed and reopened in a substantially continuous movement.

15. The method of claim 13, wherein monitoring further comprises:

generating an output signal from a motion sensor attached to said diesel engine, wherein said output signal is indicative of said motion level.

16. The method of claim 15, further comprising:

comparing said output signal to said at least one threshold value.

17. The method of claim 13, wherein substantially closing and reopening said first valve further comprises:

generating a first valve control signal operative to move said valve from an initial valve position defining a first gaseous-fuel flow volume to a substantially closed position defining a second gaseous-fuel flow volume; and

generating a second valve control signal operative to move said valve from said substantially closed position to a reopened position defining a third gaseous-fuel flow volume.

18. The method of claim 17, wherein said first gaseous-fuel flow volume and said third gaseous-fuel flow volume are different.

19. The method of claim 17, further comprising:

obtaining an exhaust oxygen value, wherein said third gaseous-fuel flow volume associated with said reopened position is based at least in part on said oxygen content value.

20. The method of claim 19, wherein said exhaust oxygen value is obtained after said first valve is substantially closed.

21. The method of claim 13, further comprising passing said gaseous-fuel flow through a second valve disposed between said gaseous-fuel supply and said air intake stream of said diesel engine, wherein said second valve is operative for regulating said volume said gaseous-fuel flow based on an engine load level.

22. The method of claim 21, further comprising:

operating said second valve based on a boost pressure of a turbocharger associated with said diesel engine.

23. The method of claim 13, further comprising:

generating said at least one threshold value during operation of said engine.

24. The method of claim 13, further comprising:

obtaining said threshold value from a memory structure containing a set of predetermined threshold values.

25. A gaseous-fuel fumigation system for use with a diesel engine, comprising:

a first valve disposable in a flow path between a gaseous-fuel supply and an air intake stream of a diesel engine, the first valve being operative to regulate a flow volume of a gaseous-fuel through the flow path;

a knock sensor operative to monitor a motion level of said diesel engine and generate an output signal indicative of said motion level;

an oxygen sensor disposed in an exhaust stream of said diesel engine and being operative to generate an oxygen content signal; and

a controller operative to;

receive the output signal from the knock sensor and the oxygen content signal from the oxygen sensor; and

compare said output signal to at least a first threshold value; and

upon said output signal exceeding said first threshold value, generate a first control signal operative to close said first valve and generate a second control signal operative reopen said first valve, wherein said second control signal is based at least in part on said oxygen content signal.