Piston for Diesel engine fuel injection pump - has tapered helical groove and longitudinal recess in side to give smoother flow

摘要

The piston reciprocates linearly in a cylinder and can be rotated about its axis to vary the volume discharge for a constant stroke. The piston has a lower section with an upper section above. The upper section has an annular groove round it. The bottom edge of this groove is perpendicular to the axis of the piston while the upper edge spirals along the piston to form a groove with a width which tapers round the circumference of the piston. A recess runs longitudinally along the side of the piston parallel to the axis. It starts from the top face of the piston and runs through the annular groove the whole width of the groove at its widest part.