Electromagnetic fuel delivery and metering pump

Electromagnetic fuel delivery pump, comprising a diaphragm pump that delivers in excess and a metering piston pump, said pumps having working chambers and means enabling interconnection thereof when the diaphragm pump executes a delivery stroke and the metering piston pump executes a suction stroke, said metering piston pump having a piston connected with an armature of an electromagnetic, and a common return spring being provided for executing the delivery stroke of the diaphragm pump and the suction stroke of the piston metering pump, wherein a diaphragm of the diaphragm pump is disposed directly on an extension of the piston of the metering piston pump, wherein the piston and its extension have a penetrating lengthwise bore in which a suction valve is disposed, opening into the working chamber of the diaphragm pump, and wherein an end of the piston extension that penetrates into the working chamber of the diaphragm pump is pressed in the inoperative position of the pump against a seal by the return spring.

Electromagnetic fuel delivery pump, comprising a diaphragm pump that delivers in excess and a metering piston pump, said pumps having working chambers and means enabling interconnection thereof when the diaphragm pump executes a delivery stroke and the metering piston pump executes a suction stroke, said metering piston pump having a piston formed with an extension that is connected with an armature of an electromagnet and with a diaphragm pump, and a common return spring being provided for executing the delivery stroke of the diaphragm pump and the suction stroke of the piston metering pump, said return spring being mounted about said piston with a displaceable end thereof in abutment with said armature, wherein the diaphragm pump, the metering piston pump and coils of the electromagnet are disposed in a common housing, and wherein a suction chamber and a pressure chamber in said housing communicate with the working chamber of the diaphragm pump via respective oppositely acting check valves, whereby a quantity of fluid drawn in by the diaphragm from said suction chamber during its suction stroke in excess of that which is delivered to the metering pump during the delivery stroke of the diaphragm pump is discharged to said pressure chamber.