Pressure control valve for a fuel system

A bypass pressure control unit for a fuel delivery system for an internal combustion engine having a fuel pump with its output connected to a fuel delivery line of the system comprising:

• a housing, a flexible diaphragm valve made from a planar sheet of flexible fuel impervious material of uniform thickness and defining with said housing a first chamber and a second chamber, said housing having at least one port defining a fuel inlet adapted for continuous communication between the fuel delivery line and said first chamber, a fuel bypass outlet port communicating with said second chamber, a rigid valve seat formed in said housing between said chamber, a spring in said housing for biasing said diaphragm to directly bear on said valve seat to sealably isolate said first chamber from the fuel bypass outlet port via said second chamber, and said diaphragm, spring and valve seat being constructed and arranged such that when force of fluid pressure in said first chamber overcomes the force exerted by said spring on said diaphragm, said diaphragm is disengaged from said valve seat to thereby open communication of said first chamber with the fuel bypass outlet port via said second chamber, and vice versa when the spring force overcomes such fluid pressure force;
• to thereby regulate the pressure of fuel in said fuel delivery line, and wherein said valve seat is in the form of an annulus defining with said diaphragm when sealably engaged thereon an annular valve seat barrier between said first and second chambers.

A fuel delivery system for an internal combustion engine that includes a fuel supply with a pump responsive to application of electrical power for delivering fuel under pressure, an engine air intake manifold, fuel delivery means coupled to said fuel supply for controlled delivery of fuel from said supply to said manifold, pressure regulator means having an inlet means responsive to fuel pressure at said fuel delivery means and outlet means connected through a fuel return to said supply, said regulator means being responsive to a predetermined pressure differential across said fuel delivery means for passing excess fuel through said return to said supply, characterized in that said regulator means comprises:

• a flexible diaphragm valve made from a planar sheet of flexible fuel impervious material of uniform thickness, and an associated rigid valve seat defining with said outlet means and said inlet means a first chamber and a second chamber respectively, spring means for biasing said diaphragm to directly bear on said valve seat to sealably isolate said first chamber from said bypass outlet means via said second chamber, and wherein said diaphragm, spring and valve seat are constructed and arranged such that when force of fuel pressure in said first chamber overcomes the force exerted by said spring on said diaphragm, said diaphragm is disengaged from said valve seat to open communication of said first chamber with the fuel bypass outlet means via said second chamber, and vice versa when the spring force overcomes such fuel pressure force, to thereby regulate the pressure of fuel in said fuel delivery means, and wherein said valve seat is in the form of an annulus defining with said diaphragm when sealably engaged thereon an annular valve seat barrier between said first and second chambers.