GB535301A - Improvement in pumps - Google Patents

Abstract

535,301. Fuel-injection pumps. BENDIX AVIATION CORPORATION. Oct. 3, 1939, No. 27119. Convention date, Oct. 6, 1938. [Class 102(i)] In a pump having axially spaced intake and byepass ports, in the casing, turbulence is reduced by providing the casing with circumferential grooves which communicate with the ports and fuel-inlet at circumferentially spaced points. Alternatively, only one of the grooves communicates with the fuel-inlet. To reduce erosion, the grooves may be formed in a liner of stainless steel or other hard metal. In the pump shown in the Figure a plunger 13 reciprocates in a cylinder 7 which is secured in a casing 5 and is surmounted by a delivery-valve 31. The cylinder is formed with intake and byepass ports 11, 12 and the plunger is formed with axial and radial bores 14, 15 communicating with helical, cut-off and pressure-balancing grooves 16, 17. A liner 39 in the casing is formed with a rib 45 to provide grooves 46, 47 which communicate with the fuel-inlet 43. The rib embraces the cylinder over half the circumference and then tapers off. A hardened-steel screw 49 having a tip 50 may be arranged opposite the port 12. When the plunger rises, the port 11 is cut-off and fuel is delivered through the valve 31 until the groove 16 overlaps the port 12. Thereupon fuel is byepassed through the port 12 and strikes the liner 39 and screw-tip 50, the rib 45 preventing turbulence from being transmitted to the fuel in the supply-groove 46. In an alternative arrangement, the rib 45 surrounds the cylinder and cuts off the groove 47 from the fuel-inlet, and the fuel is byepassed through a fitting which replaces the screw 49. To regulate delivery, the plunger is angularly adjusted by means of a rack 20 and a co-operating sleeve 18 which engages a spline 23 on the plunger. The valve 31 is mounted in an adapter 30 secured by a nut 32.