Plug-in Pump Fluid Separation via Segmented Housing

The pump housing cavity is divided into two separate spaces (first space for fuel, second space for engine oil) that are fluidly separated from each other. This segmentation prevents fuel and engine oil from mixing while maintaining separate lubrication and pumping functions, directly addressing the reliability issue without requiring complex sealing mechanisms at fluid interfaces.

A sealing element is introduced as an intermediary component between the first and second spaces to prevent fluid mixing. The sealing element acts as a mediator that maintains fluid separation while allowing the piston to function, resolving the contradiction between simple structure and reliable separation.

The spring mechanism is segmented into two separate springs (first spring in the first space, second spring in the second space), each acting independently on the piston. This segmentation provides redundant return forces and ensures reliable piston operation even if one spring fails, while maintaining relatively simple individual spring structures.

Each spring is positioned in its respective fluid space to provide localized support and return force. The first spring is surrounded by the first fluid (fuel) and the second spring by the second fluid (engine oil), allowing each spring to be optimized for its specific environment while collectively providing reliable piston return force.

The cavity inner diameter is designed to substantially correspond to the piston outer diameter, creating a precise fit that minimizes the gap between the piston and cavity wall. This local precision reduces the amount of fuel required for cooling and lubrication while maintaining smooth piston movement through proper surface finishing and tolerances.

Instead of providing excessive clearance that would require大量 fuel for lubrication and cooling, the design uses precise dimensional matching with substantially corresponding diameters. This partial action approach provides just enough clearance for smooth movement without excessive fuel consumption, optimizing the balance between ease of operation and fuel efficiency.