A compression ignition internal combustion engine which operates using a methane based fuel and an ignition initiator. The fuel and method of operating the engine can be employed in a range of applications such as, for example, road or marine vehicles or in static applications such as electrical generators.
1. A compression ignition engine arranged to operate using a mixture of a fuel gas and an ignition initiator, the engine comprising: a fuel delivery system that receives the fuel gas from a first tank in a liquefied or pressurised state and receives the ignition initiator from a second tank separate from the first tank, and in which the gas and ignition initiator are received separately and then mixed to produce a liquefied or pressurised mixture; the engine further comprising an injector for receiving the mixture and injecting it into a combustion chamber of the engine.
2. A compression ignition engine as claimed in claim 1 , wherein the fuel gas comprises a methane based gas.
3. A compression ignition engine as claimed in claim 2 , wherein the methane based gas comprises natural gas.
4. A compression ignition engine as claimed in claim 1 , wherein the engine is a diesel-cycle engine.
5. A compression ignition engine as claimed in claim 1 wherein the ignition initiator comprises diesel fuel.
6. A compression ignition engine as claimed in claim 1 , wherein the fuel gas comprises propane or LPG.
7. A fuel delivery system as claimed in claim 1 , wherein the fuel gas is a pressurised fuel gas, the mixture is a pressurised mixture, and the pressurised mixture has a pressure of at least 500 bar.
8. A method of operating a compression ignition engine using a gas based fuel wherein a liquefied or pressurised fuel gas from a first tank is mixed with an ignition initiator from a second tank separate from the first tank in a fuel delivery system of the engine in order to produce a liquefied or pressurised mixture, the mixture is then supplied to an injector, and the injector injects the mixture into the combustion chamber of a compression ignition engine.
9. A method as claimed in claim 8 , wherein the fuel gas comprises a methane based gas.
10. A method of operating a compression ignition engine as claimed in claim 9 , wherein the methane based gas is natural gas.
11. A method as claimed in claim 8 , wherein the ignition initiator comprises diesel fuel.
12. A method as claimed in claim 8 , wherein the gas and ignition initiator are mixed in a common rail fuel delivery system.
13. A method as claimed in claim 8 , wherein the fuel gas comprises propane or LPG.
14. A fuel delivery system as claimed in claim 8 , wherein the fuel gas is a pressurised fuel gas, the mixture is a pressurised mixture, and the pressurised mixture has a pressure of at least 500 bar.
15. A fuel injector assembly comprising a fuel injector and a separate fuel mixing unit, wherein the mixing unit receives a first fuel component from a first tank in the form of a liquefied or pressurised gas and a second fuel component from a second tank separate from the first tank in the form of an ignition initiator and wherein the mixing unit mixes the first and second fuel components to produce a liquefied or pressurized mixture and then supplies the mixed fuel to the injector.
16. A fuel injector assembly as claimed in claim 15 , wherein the injector is a hydraulically activated injector.
17. A fuel injector assembly as claimed in claim 15 used in combination with a compression ignition engine.
18. A fuel injector assembly as claimed in claim 15 , wherein the first fuel component comprises a methane based gas.
19. A fuel injector assembly as claimed in claim 18 , wherein the methane based gas comprises natural gas.
20. A fuel injector assembly as claimed in claim 15 , wherein the first fuel component comprises propane or LPG.
21. A fuel delivery system as claimed in claim 15 , wherein the fuel gas is a pressurised fuel gas, the mixture is a pressurised mixture, and the pressurised mixture has a pressure of at least 500 bar.
22. A fuel delivery system for a compression ignition engine wherein a mixture of a liquefied or pressurised fuel gas from a first tank and an ignition initiator from a second tank separate from the first tank is supplied to the engine using a common fuel rail and wherein the liquefied or pressurized fuel gas is mixed with the ignition initiator in the common fuel rail to produce a liquefied or pressurised mixture.
23. A fuel delivery system as claimed in claim 22 , wherein the fuel gas comprises a methane based gas.
24. A fuel delivery system as claimed in claim 22 , wherein the first fuel component comprises propane or LPG.
25. A fuel delivery system as claimed in claim 22 , wherein the fuel gas is a pressurised fuel gas, the mixture is a pressurised mixture, and the pressurised mixture has a pressure of at least 500 bar.