TL960 SERVICE MANUAL
multiplication of force. The downward movement of the plunger pressurizes the fuel in the plunger cavity, causing the nozzle to open. Thus 3,000 psi oil provides fuel injection pressures of 21,000 psi.
Nozzle Assembly: The nozzle assembly is of conventional design with the exception of the fill check. This check ball seats and seals during the downward stroke of the plunger to prevent leakage of the high pressure fuel. During the return stroke, it unseats allowing the plunger cavity to fill. The nozzle valve is an inwardly opening type which lifts off its seat when pressure overcomes the spring force. Fuel is then atomized at high pressure through the nozzle tip.
Stages of Injection
There are three stages of injection with HEUI:
Fill Cycle: During pre-injection all internal components have returned to their spring loaded (non-actuated) positions. The solenoid is not energized and the poppet valve is