GB423030A - Improvements in liquid fuel injection pumps - Google Patents

Abstract

423,030. Fuel - injection pumps. OLDHAM, R., Holmwood, Cleethorpes, Lincolnshire. June 19, 1933, No. 17367. [Class 102 (i)] In a fuel-injection pump in which a recess 6, Fig. 3, in the plunger makes communication between a recess 3 in the barrel and a relief port 5, both ends of the recess 6 are closed during a part of the stroke. The plunger is rotatable relatively to the barrel, and the recess 6 is formed with a helical edge 6<x>, which co-operates with the recess 3 and with the port 5. The inclination of the parts of the edge 6<x> which co-operate with the recess 3 and with the port 5 may be different, and the recess 3 may be uncovered before or after the port 5, in order to effect a preliminary partial relief of pressure. A partial relief of pressure may also be effected by a groove 6 in the plunger, co-operating with the recess 3 before the recess 3 communicates with the recess 6. Alternatively, preliminary relief may be effected by a passage 3<x>, Fig. 5, from the recess 3. This Figure also shows a modification in which separate edges 6x, 6<y> of the recess 6 co-operate with the recess 3 and with the suction port 4 to terminate injection. As shown in dotted lines a lower recess may also be provided with edges 6x, 6<y> which co-operate with the passage 3x, and with the port 5. The plunger in its lowest position may extend above the suction port 4, the fuel entering the barrel through a groove in the plunger and through the recess 3. In the modification shown in Fig. 8, the recess 3 is helical, and the recess 6 is formed with an axial extension 6<y>, which co-operates with the recess 3 to effect preliminary relief.