GB474731A - Regulating apparatus for fuel injection pumps of internal combustion engines - Google Patents

Abstract

474,731. Fluid-pressure servomotors. SCINTILLA, Ltd. April 21, 1937, No. 11385. Convention date, April 21, 1936. [Class 135] In a regulating device for a fuel-injection pump for an internal-combustion engine, a control fluid passes through a pressure regulator and a restricted passage, the fluid pressure ahead of the regulator acting on a servomotor for controlling the fuel delivery, and the pressure ahead of the restricted passage acting on a servomotor for controlling the timing of the injection. In the form shown, the shaft 2 of the fuel-pump (not shown) drives a gear pump 3, 5, which feeds control fluid from the inlet 21 into a chamber 22, where pressure is maintained substantially constant for all speeds of the shaft 2 by a spring-pressed plunger 23 controlling the outlet 28. The fluid then passes to a chamber 29, the pressure in which rises with speed of the shaft 2 (i.e. with engine speed) owing to the restricted outlet 24, which, where the control fluid is liquid fuel, leads to the suction side of the fuel-pump. The constant pressure from the chamber 22 passes through a conduit 37 to the space 36 behind a servomotor piston 34, which through a link 33 and a rod 31 controls the delivery of the fuel-pump. The space 36 is connected through a restriction 45, longitudinal bore 43, and openings 44 with a space 38 acting on a larger area on the opposite face of the piston. The end of the bore 43 abuts against a stem 9, and fluid leaks continually through the junction in order to maintain a pressure in space 38 which is lower than that in space 36. If the stem 9 moves to the right, the pressure in space 38 falls and the piston 34 follows the stem. The position of the stem 9 is conjointly controlled by a spring 12 and by governor-weights 4. The weights 4 are pivoted on arms 6 on the wheel 5 of the gearpump and are thus revolved according to'engine speed. When the control-rod 18 is moved to the left the spring 12 is urged to the right through fork 17 and abutment 13. The spring 12 is calibrated so that for a given setting of the control-rod 18 the speed of the engine is maintained substantially constant by the weights 4. Movement of the stem 9 to the right to give the highest fuel-pump deliveries, however, is prevented by an abutment 63 until the speed of the engine has reached a certain limit, the abutment 63 being held in the position shown at lower speeds by the pressure in space 67 derived from the constant pressure in chamber 22 and being moved to the right only when the pressure from chamber 29 acting in the annular chamber 65 becomes high enough. The pressure from the chamber 29 is supplied through a conduit 62 also to a piston 59 having a stem, which controls a follow-up servomotor piston 47 as described for piston 34, pressure from the chamber 22 being supplied to the space 50 through conduit 37. The rod 46 of piston 47 is connected to the timing apparatus for the fuel-pump.