Diesel Distributor Fuel-Injection Pumps VE - Gnarlodious

– Maximum-speed governing: With theaccelerator pedal fully depressed, themaximum full-load speed must notincrease to more than high idle speed(maximum speed) when the load isremoved. Here, the governor respondsby shifting the control collar back towardsthe “Stop” position, and the supply of fuelto the engine is reduced.– Intermediate-speed governing: Variable-speedgovernors incorporate intermediate-speedgoverning. Withincertain limits, these governors can alsomaintain the engine speeds betweenidle and maximum constant. Thismeans that depending upon load, theengine speed n varies inside the engine’spower range only between n VT(a given speed on the full-load curve)and n LT (with no load on the engine).Other control functions are performedby the governor in addition to its governingresponsibilities:– Releasing or blocking of the extra fuelrequired for starting,– Changing the full-load delivery as aFig. 2Governor characteristicsa Minimum-maximum-speed governor,b Variable-speed governor.1 Start quantity, 2 Full-load delivery,3 Torque control (positive),4 Full-load speed regulation, 5 Idle.abmmControl-collar travelmmControl-collar travel5512 3 412 3 40 Engine speed min –1UMK0344Efunction of engine speed (torque control).In some cases, add-on modules arenecessary for these extra assignments.Speed-control (governing) accuracyThe parameter used as the measure forthe governor’s accuracy in controllingengine speed when load is removed isthe so-called speed droop (P-degree).This is the engine-speed increase,expressed as a percentage, that occurswhen the diesel engine’s load is removedwith the control-lever (accelerator)position unchanged. Within thespeed-control range, the increase inengine speed is not to exceed a givenfigure. This is stipulated as the high idlespeed. This is the engine speed whichresults when the diesel engine, startingat its maximum speed under full load, isrelieved of all load. The speed increase isproportional to the change in load,and increases along with it.δ = n lo – n von voor expressed in %:δ = n lo – n vo . 100%n vowhereδ = Speed droopn lo = High idle (maximum) speed= Maximum full-load speedn voThe required speed droop depends onengine application. For instance, on anengine used to power an electrical generatorset, a small speed droop is requiredso that load changes result inonly minor speed changes and thereforeminimal frequency changes. On theother hand, for automotive applicationslarge speed droops are preferablebecause these result in more stablecontrol in case of only slight loadchanges (acceleration or deceleration)and lead to better driveability. A low-valuespeed droop would lead to rough, jerkingoperation when the load changes.Mechanicalgoverning23