High pressure gaseous fuel supply system for an internal combustion engine and a method of sealing connections between components to prevent leakage of a high pressure gaseous fuel

• US 7,308,889 B2
• Filed: 03/20/2006
• Issued: 12/18/2007
• Est. Priority Date: 09/23/2003
• Status: Expired due to Fees

• Current Assignee: Westport Power Inc. (Westport Fuel Systems, Inc.)
• Original Assignee: Westport Power Inc. (Westport Fuel Systems, Inc.)
• Inventors: Post, Adrian J., Brook, Thomas C.
• Primary Examiner(s): Kamen, Noah P.
• Application Number:
  US11/277,013
• Publication Number:
  US 20060213488A1
• Time in Patent Office: 638 Days
• Field of Search: 123/27.GE, 123/527
• US Class Current: 123/527
• CPC Class Codes: F02M 21/0215 Mixtures of gaseous fuels; Natural gas; Biogas; Mine gas; Landfill gas
• CPC Class Codes: F02M 21/0221 Fuel storage reservoirs, e.g. cryogenic tanks
• CPC Class Codes: F02M 21/0239 Pressure or flow regulators therefor
• CPC Class Codes: F02M 21/0263 Inwardly opening single or multi nozzle valves, e.g. needle valves
• CPC Class Codes: F02M 21/0287 characterised by the transition from liquid to gaseous phase F02M21/06 takes precedence; Injection in liquid phase; Cooling and low temperature storage
• CPC Class Codes: F02M 21/0293 Safety devices; Fail-safe measures
• CPC Class Codes: F02M 21/0296 Manufacturing or assembly; Materials, e.g. coatings
• CPC Class Codes: F02M 55/005 for high pressure conduits, e.g. connected to pump outlet or to injector inlet
• CPC Class Codes: F02M 61/04 having valves , e.g. having a plurality of valves in series
• CPC Class Codes: F02M 63/0225 Fuel-injection apparatus having a common rail feeding several injectors F02M63/0003 takes precedence; Means for varying pressure in common rails; Pumps feeding common rails
• CPC Class Codes: Y02T 10/30 Use of alternative fuels, e.g. biofuels

Abstract

A high-pressure fuel system supplies gaseous fuel to an internal combustion engine. Gaseous fuel pressure within the system is at least 17 MPa during normal operation. The system comprises a number of components and conduits and at least one resilient member for sealing at an interface between two components. The resilient member consists essentially of thermoplastic polyurethane. A corresponding method provides sealing between components containing gaseous fluids at pressures that can be above 17 MPa, in which the gaseous fluids routinely undergo rapid reductions in pressure. The method comprises disposing a resilient member, which consists essentially of thermoplastic polyurethane, at an interface between the components. Gas pressure fluctuations can occur during operation of the components or when the high-pressure gas is vented from the components upon shut down of the high-pressure system. A particularly suitable application for the present method is high-pressure gaseous fuel supply systems for internal combustion engines.

Claims

1. A fuel system for supplying a gaseous fuel to an internal combustion engine, said system comprising a thermoplastic polyurethane material provided at an interface between two components of said system or between parts of one of said components for sealing therebetween, wherein said components comprise:

(a) a pressure increasing module;

(b) a fuel conditioning module;

(c) a fuel injection valve for injecting said fuel directly into a combustion chamber of said internal combustion engine; and

(d) conduits for conveying said gaseous fuel from said pressure increasing module to said fuel conditioning module, and from said fuel conditioning module to said fuel injection valve, wherein said conduits can be separate components or integral to an engine part, including other ones of said fuel system components.

2. The fuel system of claim 1 wherein pressure of said gaseous fuel within said system is at least 17 MPa during normal operation and said pressure routinely undergoes rapid reductions in pressure.

3. The fuel system of claim 1 wherein said thermoplastic polyurethane has a chemical backbone material that is selected from the group consisting of p-phenylenediisocyanate, diphenyldiisocyante, and diphenylmethane diisocyanate.

4. The fuel system of claim 1 wherein a resilient member, which comprises said thermoplastic polyurethane material, is held in compression when installed at said interface.

5. The fuel system of claim 1 wherein said components are shaped to receive and hold a resilient member, which comprises said thermoplastic polyurethane material, at a location at said interface where sealing is desired.

6. The fuel system of claim 1 wherein a resilient member, which comprises said thermoplastic polyurethane material, is in the shape of a closed circular ring.

7. The fuel system of claim 1 wherein a resilient member, which comprises said thermoplastic polyurethane material, has a circular cross-section.

8. The fuel system of claim 1 wherein said gaseous fuel is a combustible hydrocarbon derivative.

9. The fuel system of claim 1 wherein said gaseous fuel is selected from the group consisting of natural gas, methane, propane, ethane, hydrogen, and blends thereof.

10. The fuel system of claim 1 wherein said fuel conditioning module comprises a pressure regulating device to control the pressure of said gaseous fuel within said fuel injection valve.

11. The fuel system of claim 10 wherein said pressure regulating device is operable to control fluid pressure within said fuel injection valve to fluctuate within a range of pressures between about 17 MPa and up to about 70 MPa during normal operation of said components.

12. The fuel system of claim 10 wherein pressure regulating device is operable to control fluid pressure within said fuel injection valve to be between at least 19 MPa and 35 MPa during normal operation of said components.

13. The fuel system of claim 1 wherein fluid pressure within said components is ventable to atmospheric pressure when said engine is shut down.

14. The fuel system of claim 1 wherein said fuel conditioning module further comprises a vent that is openable to reduce the pressure of said gaseous fuel that is remaining within said components when said engine is shut down.

15. The fuel system of claim 1 wherein fuel conditioning module further comprises a gas filter through which said gaseous fuel flows for separating contaminants from said gaseous fuel and said interface is between said gas filter and connections for fuel passages of said fuel conditioning module.

16. The fuel system of claim 1 wherein operation of said fuel conditioning module is controllable by an electronic controller.

17. The fuel system of claim 1 wherein said components are integral with or in contact with engine parts that can be heated during operation of said engine, whereby at said interface said components can have a constant surface temperature of up to 200°

C.

18. The fuel system of claim 17 wherein said thermoplastic polyurethane has a chemical backbone material that comprises p-phenylenediisocyanate.

19. The fuel system of claim 1 wherein said pressure increasing module is a pump for pumping liquefied gases and said fuel system further comprises a vaporizer for converting liquefied gas to a gaseous phase after it has been discharged from said pump.

20. The fuel system of claim 1 wherein said conduits between said fuel conditioning module and said fuel injection valve comprise a bore provided within a cylinder head and a resilient member, which comprises said thermoplastic polyurethane material, provides a static seal at said interface, which is between said fuel injection valve and said cylinder head.

21. The fuel system of claim 20 wherein said conduits between said fuel conditioning module and said fuel injection valve comprise a bore provided within a cylinder head and a resilient member, which comprises said thermoplastic polyurethane material, provides a static seal at said interface, which is between a plug that seals an open end of said bore and said cylinder head.

22. The fuel system of claim 1 wherein said fuel conditioning module comprises a dome-loaded regulator through which said gaseous fuel flows and said resilient member provides a dynamic seal at said interface, which is between a piston of said dome-loaded regulator and a cylinder within which said piston is disposed.

23. A method of sealing at an interface between components or parts of a component of a fuel system for supplying a gaseous fuel to an internal combustion engine at pressures that can be above 17 MPa, wherein said gaseous fuel routinely undergoes rapid reductions in pressure, said method comprising disposing a resilient member that provides a fluid seal at said interface, said resilient member consisting essentially of thermoplastic polyurethane.

24. The method of claim 23 wherein said thermoplastic polyurethane has a chemical backbone material that is selected from the group consisting of p-phenylenediisocyanate, diphenyldiisocyante, and diphenylmethane diisocyanate.

25. The method of claim 23 wherein pressure of said gaseous fuel within said components fluctuates within a range of pressures between about 17 MPa and up to about 70 MPa during normal operation of said components.

26. The method of claim 23 wherein pressure of said gaseous fuel within said components is controllable to be between at least 19 MPa and about 35 MPa during normal operation of said components.

27. The method of claim 23 wherein pressure of said gaseous fuel within said components is ventable to atmospheric pressure when said engine is shut down.

28. The method of claim 23 further comprising compressing said resilient member when installed at said interface.

29. The method of claim 23 further comprising shaping said components to receive and hold said resilient member at a location at said interface where sealing is desired.

30. The method of claim 23 wherein said resilient member is a static seal.

31. The method of claim 23 wherein said resilient member is in the shape of a closed circular ring.

32. The method of claim 23 wherein said resilient member has a circular cross-section.

33. The method of claim 23 wherein the frequency of said rapid reductions in pressure is between 1 hertz and 10 hertz when said engine is running under load.

34. The method of claim 23 wherein during operation of said engine, said resilient member can be exposed to constant temperatures up to 200°

C.

35. The method of claim 34 wherein said resilient member has a chemical backbone comprising p-phenylenediisocyanate.

36. The method of claim 23 wherein said gaseous fuel is a combustible hydrocarbon derivative.

37. The method of claim 23 wherein said gaseous fuel is selected from the group consisting of natural gas, methane, propane, ethane, hydrogen, and blends thereof.

38. The method of claim 23 wherein said components comprise a fuel injection valve and conduits for conveying said gaseous fuel to said fuel injection valve comprise a bore made in an engine cylinder head and said interface is between said fuel injection valve and said cylinder head.

39. The method of claim 23 wherein said component is a conduit defined by a bore made in an engine cylinder head and said interface is between said fuel injection valve and said cylinder head.

40. The method of claim 23 wherein said fuel system comprises a dome-loaded regulator through which said gaseous fuel flows for controlling fuel pressure delivered to a fuel injection valve and said interface is inside said dome-loaded regulator between a reciprocable piston and a cylinder within which said piston is disposed.