| 摘要 |
<p>A liquid fuel injection pumping apparatus comprises a reciprocable pump plunger operable by a tappet assembly and a rotary cam. The tappet assembly includes a cylindrical body slidable within a bore, the body carrying a cross pin which supports a roller engageable with the cam. The cross pin has reclined ends so that if it moves axially while exposed beyond the end of the bore it will engage the bore and move axially to its correct position. With cams designed to give maximum plunger movement the pin is exposed for an appreciable time and heavy wear of the pin and bore can occur. The cam is therefore designed to allow outward movement of the plunger but then to hold the plunger until just before inward movement of the plunger is required to take place. Whilst the plunger is held the filling port of the pump is at least partly uncovered. The cam has a trailing flank which comprises a first part during which the plunger can move outwardly, a second part during which the plunger is held against outward movement and a third part which allows the full outward movement.</p> |
