GB690555A - Improvements relating to fuel-pump regulating means for injection-type internal combustion engines - Google Patents

Abstract

690,555. Fluid-pressure servomotor control systems. DAIMLER-BENZ AKT.-GES. March 8, 1950 [March 8, 1949], No. 5888/50. Class 135 In a hydraulic regulating means for the fuelinjection pump of an internal-combustion engine, fluid at a pressure dependent upon engine speed acts on one side of a regulating piston, against a resisting force, in the direction for increasing the quantity of fuel injected, but, when the said pressure exceeds a value predetermined by the driver, a valve-controlled passage through the piston is automatically opened and regulating fluid passes to the opposite side of the piston to augment the resisting force acting thereon to urge the piston in the direction for reducing the quantity of fuel injected. In an embodiment, the cam shaft 2 driving the fuel-injection pump pistons 3 also carries an eccentric disc actuating the reciprocating pistons of a separate combined fuel and governor pump. The input to the latter pump is drawn from the main pump housing and a low pressure output is fed to the suction space 37 of the main pump. A second output at a higher pressure corresponding to the speed of the engine is fed to a chamber 15 where it can act on a piston 9 connected by links and a lever 7 to the rack controlling the output of the main pump. The liquid in chamber 15 also flows through restrictions 16 into the interior of telescoping tubular sections 11, 13 where it can act on a relief-type valve 20. On starting the engine, the piston 9 is forced to the right to its limiting position to give full output from the main pump. If the spring loading of valve 20 has been set by hand lever 23 to give idling conditions, the pressure in chamber 15, &c. will soon overcome the spring loading of valve 20 and will open the latter so that, besides venting chamber 15, the liquid also flows to the back of piston 9 to assist the loading spring to force the piston to the left and so reduce the output of the main pump. The engine can be set for higher speeds by increasing the spring loading on valve 20 by means of lever 23. Tube 13 is fixed to the casing containing piston 9. Both sides of the piston 9 are continuously vented through restrictions 27, 28, and restriction 16 may constitute a valve which does not open until the piston has moved some distance to the right.