| 摘要 |
A fuel vapour extraction system is described for an internal combustion engine (10) that is supplied with a volatile liquid fuel from a fuel storage tank (20). The engine (10) has an air intake system (12, 14, 16) and a liquid fuel injection system for dispensing fuel to mix with air to be burnt in the engine. The fuel vapour extraction system includes a volatizing chamber (30) connected to the fuel storage tank (20) by a valve (26) serving to maintain a constant liquid level of fuel in the chamber (30). A pipe (42) connected to one or more vacuum sources leads into the vapour space above the liquid level in the chamber (30) and maintains a reduced pressure in the volatizing chamber. The fuel injection system includes a fuel circulation pump (32) for drawing liquid fuel from the volatizing chamber (30) and supplying the fuel under pressure to a fuel rail (34), fuel injectors (18) for dispensing metered quantities of fuel from the fuel rail (34) to the engine cylinders, and a relief valve (36) for maintaining a constant fuel pressure in the fuel rail (34) and returning unused fuel from the fuel rail (34) to the reduced pressure vapour space in the volatizing chamber (30) by way of a fuel return pipe (38). An evaporator (40) is provided in the vapour space of the volatizing chamber (30) to act as a means for increasing the surface area to volume ratio of the return fuel. The return fuel comes into intimate thermal contact with the evaporator (40) and spreads over a large area of the evaporator (40) exposed to the reduced pressure in the volatizing chamber (30).
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