Variable drive coupling for a fuel injection pump

摘要

The drive shaft of a fuel injection pump is coupled to a power imparting shaft via a centrifugal coupling in which pivoting flyweights determine the relative angular position of the driven and driving shafts. A return spring opposes the outward motion of the flyweights and it is supported on a movable support which can be displaced by hydraulic pressure. The magnitude of the hydraulic pressure determines the relative angular position of the two shafts at any time. A sleeve engages the driving shaft by means of a tongue and groove coupling which is helical so that the imparted torque causes an axial displacement of the sleeve, resulting in a change in the overflow cross section for the hydraulic fluid, thereby altering the effective pressure on the spring support. This changes the relative angle of the two shafts which, in turn, alters the onset of fuel injection.