High accuracy dispensing pump for chromatography - has plungers held in contact with swashplate with curved track to reduce inaccuracy

摘要

The liquid dispersing pump requiring a high degree of accuracy, such as for chromatography has a rotating base with a spindle (6) projecting from its centre which can be raised and lowered to vary the angle of a swashplate (4). A number of plungers (2) are forced down against the surface of the swashplate by springs (3), to control the delivery of fluid to a corresponding number of supply points. The angle of tilt of the swashplate determines the quantity delivered. In order to eliminate inaccuracies introduced when a flat swashplate is used, the rounded tips (26) of the plungers are held in contact with the convex surface of a circular track (7a) around the flat surface (4a) of the swashplate, giving point contact. The swashplate can be tilted about its horizontal hinge axis (5) by the movement of a tongue (40) projecting from its periphery, in contact with a cam surface (9) which can rise and fall below.