Carburetor fuel supply system

摘要

A purge and prime assembly for a carburetor includes a purge and prime pump that alternately takes in and discharges fluid, and a plurality of passages through which fluid is routed. The passages may include a purge passage through which fluid is drawn by the purge and prime pump, a return passage through which fluid is discharged from the purge and prime pump and discharged from the carburetor, and a priming passage through which a portion of the fluid discharged from the purge and prime pump is routed to a main bore of the carburetor. The assembly may also include a purge valve that prevents fluid from being discharged from the purge prime pump through the purge passage, and a return valve that prevents fluid in the return passage from being drawn into the purge and prime pump.

主权项

1. A purge and prime assembly for a carburetor, comprising:
a purge and prime pump that alternately takes in and discharges fluid; a purge passage through which fluid is drawn by the purge and prime pump; a return passage through which fluid is discharged from the purge and prime pump and discharged from the carburetor; a purge valve that prevents fluid from being discharged from the purge and prime pump through the purge passage; a return valve that prevents fluid in the return passage from being drawn into the purge and prime pump; a priming passage communicating with the purge and prime pump and having an outlet directly communicating with a main bore of the carburetor and through the outlet a portion of the fluid discharged from the purge and prime pump is routed to the main bore of the carburetor; a flow restrictor in the priming passage comprising a sheet of material with a thickness in the direction of fluid flow of not more than 0.35 mm and having a single hole through which all of the priming fuel flows with a diameter in the range of 0.05 mm to 0.3 mm and the flow restrictor defines the maximum restriction to flow in the priming passage; and the ratio of flow area of the flow restrictor to the minimum effective flow area of the purge passage is between 0.025:1 to 0.2:1.