GB1249162A - Improvements in or relating to fuel injection pumps - Google Patents

Abstract

1,249,162. Fuel injection pumps. ROBERT BOSCH G.m.b.H. Feb.14, 1969 [Feb.16, 1968], No.8025/69. Heading F1A. A fuel injection pump is of the type in which the quantity of fuel delivered is varied according to engine speed by a regulating spool 14 which controls the opening of a spill passage 15b and which is driven in one direction by pressure liquid delivered from an auxiliary pump 18, 19 driven synchronously with the injection pump, the return stroke of the spool 14 being retarded by a variable regulating throttle 30. The auxiliary pump has a by-pass passage 33a which has a throttle comprising a throttle 48, Fig.2, and a closing element 35 which is opened by a spring 37 and closed by speed dependant pressure liquid. The crosssection of the throttle 48 is variable simultaneously with the cross-section of the regulating throttle 30 by rotating the member 28. The cross-section 30 may also be varied by axial movement of the member 28. For starting the cross-section 30 is opened together with the throttle 48 and the closing element 35, and thus all the fuel delivered by the auxiliary pump flows into a suction space 4. On reaching a specific engine speed the element 35 is closed by pressure in the suction space 4 which is speed dependant and thus no more fuel can by-pass the passages 22, 25. As the engine speed continues to increase the cross-section of the regulating throttle 30 is reduced simultaneously blocking the passage 33a so that no fuel flows off by way of this passage.