Fuel pressure booster and regulator

In a fuel injection system for an internal combustion engine having at least one fuel injector connected to a single conduit, a fuel tank, a relatively low pressure pump for delivering fuel from the tank to the conduit, a uni-directional valve in the conduit to prevent reverse flow to the pump, and means connected to the conduit section which extends from the valve to the injectors for increasing the fuel flow pressure in said section above the pump outlet pressure, the improvement comprising:

• an engine driven, fuel pressure booster for elevating the pressure at which the fuel is supplied to said at least one injector to a pressure higher than the vaporization pressure of the fuel in said at least one injector, said pressure booster comprising a movable wall forming a boundary of said section;
• mechanical means including a spring for moving said wall to contract the volume of said section to maintain the pressure at which fuel is supplied to at least said one injector at a pressure higher than the vaporization pressure thereof;
• cam actuated means for periodically moving said wall to expand the volume of said section, the contraction and expansion volumes produced by said mechanical and cam actuated means being small relative to the total volume of said section;
• said system further comprising a body having a cavity provided with a flexible diaphragm forming another boundary of said section;
• said flexible diaphragm supported in the body to seal said cavity, said body connected to the conduit, said diaphragm having two sides, one side of the diaphragm facing the cavity and the other side being exposed to the fuel in the conduit, whereby said diaphragm will assume a position dependent upon the pressure exerted on it by fuel in the conduit, and will act to stabilize the fuel pressure within the conduit.

A method for elevating a pressure at which fuel is supplied to at least one injector of a fuel injection system in an engine to a pressure higher than the vaporization pressure of the fuel in said at least one injector, comprising:

• supplying fuel at a lower pressure than the elevated pressure from a system fuel supply pump to a pressure booster;
• maintaining instantaneous pressure in said pressure booster at a pressure above the fuel vaporization pressure during a cam actuated replenishment stroke in said pressure booster;
• isolating said at least one injector from a variable volume chamber in the pressure booster during said replenishment stroke of the pressure booster, the variation in chamber volume produced by said replenishment stroke being small relative to the volume of said chamber;
• isolating said variable volume chamber of the pressure booster from said fuel supply pump during a pressure boosting stroke in said pressure booster, the variation in chamber volume produced by said pressure boosting stroke being small relative to the volume of said chamber;
• maintaining substantially constant instantaneous pressure at the outlet of said pressure booster during the replenishment stroke;
• expanding said variable volume chamber of the pressure booster periodically upon actuation of said cam as a function of engine operation and
• applying pressure on said fuel in a conduit between said pressure booster and said at least one injector by mechanical means including a spring periodically and as a function of engine operation, said pressure applied to said fuel being greater than the vaporization pressure thereof.

A method for elevating a pressure at which fuel is supplied to at least one injector of a fuel injection system in an internal combustion engine to a pressure higher than the vaporization pressure of the fuel in said at least one injector, comprising:

• supplying fuel at a lower pressure than the elevated pressure from a system fuel supply pump to a pressure booster;
• maintaining instantaneous pressure in said pressure booster at a pressure above the fuel vaporization pressure during a cam actuated replenishment stroke in said pressure booster;
• isolating said at least one injector from a variable volume chamber in the pressure booster during said replenishment stroke of the pressure booster, the variation in chamber volume produced by said replenishment stroke being small relative to the volume of said chamber;
• isolating said variable volume chamber of the pressure booster from said fuel supply pump during a pressure boosting stroke in said pressure booster, the variation in chamber volume produced by said pressure boosting stroke being small relative to the volume of said chamber;
• maintaining substantially constant instantaneous pressure at the outlet of said pressure booster during the replenishment stroke;
• expanding said variable volume chamber of the pressure booster periodically upon actuation of said cam and as a function of engine operation;
• compressing a spring in the pressure booster having predetermined strength characteristics periodically and as a function of engine operation by use of power from the engine simultaneous with said step of expanding said variable volume chamber;
• and
• applying pressure on said fuel in a conduit between said pressure booster and regulator and said at least one injector periodically and as a function of engine operation by application of force from said spring, said pressure applied to said fuel being greater than the vaporization pressure thereof.