Self-contained electric-motor fuel pump with outlet pressure regulation

Claim 1

A fuel delivery system for an internal combustion engine that includes a fuel supply, an electric-motor pump for feeding fuel under pressure from said supply to the engine, and means for applying electrical power to said pump comprising: pressure sensitive switch means operatively coupled to said pump and responsive to outlet fuel pressure from said pump for switching between conductive and non-conductive switch conditions at a preselected threshold outlet fuel pressure, and pulse width modulation means coupled to said switch means for applying pulsed d.c. energy to said pump at a predetermined first frequency and duty cycle when said switch means is at one said condition indicating that said Dump outlet pressure is below said threshold, and at a predetermined second non-zero frequency and duty cycle, of which either the frequency, the duty cycle or both is less than said first frequency and duty cycle, when said switch means is at the other said condition indicating that said pump outlet pressure is above said threshold, such that electrical power applied to said electric-motor pump is reduced when Dump outlet pressure exceeds said threshold, said electric-motor pump comprising an integral assembly that includes a case and an end cap with said outlet extending from said end cap, said switch means being mounted on said end cap and responsive to fuel pressure within said case, said switch means comprising a pressure valve that includes a valve seat, a valve element and spring means urging said valve element toward said seat against fuel pressure within said housing and blocking flow of fuel through said valve when said valve element is against said seat.