US 8,297,936 B2 · Compensating temperature-induced errors during piston movement

Abstract

A method for controlling movement of a piston in a metering device is described. The method comprises supplying a fluid by actuating the metering device's piston, wherein compression or expansion of the fluid causes corresponding temperature variations. The method further comprises superposing a corrective movement onto the piston movement, with the corrective movement at least partly compensating for at least one of thermal expansion and contraction of the fluid induced by the temperature variations. In one embodiment, the corrective movement imposed onto the piston movement comprises two components: a reduction (74) of the compression jump (73), and a subsequent increase (75) of the piston's forward displacement rate (71) during a period (76) of time (72).

Claims12

Dependent claims

A method for controlling movement of a piston in a metering device, the method comprising

supplying a fluid by actuating the piston, wherein compression or expansion of the fluid, which is caused by piston movement, causes corresponding temperature variations,
superposing a corrective movement onto the piston movement, with the corrective movement at least partly compensating for at least one of thermal expansion and contraction of the fluid induced by the temperature variations, wherein the corrective movement comprises a backward displacement to at least partly compensate for the thermal expansion related to a temperature increase, and
wherein at least one of a magnitude and a time behavior of the corrective movement is dependent on the type of solvent contained in the pump chamber.

A system comprising a control unit for controlling movement of a piston in a metering device,

wherein compression or expansion of a fluid, which is caused by piston movement in a pump chamber of the metering device, causes corresponding temperature variations,
wherein the control unit is adapted for superposing a corrective movement onto the piston movement, with the corrective movement at least partly compensating for at least one of thermal expansion and contraction of the fluid induced by the temperature variations, wherein the corrective movement comprises a backward displacement to at least partly compensate for the thermal expansion related to a temperature increase, and
wherein at least one of the magnitude and the time behavior of the corrective movement is dependent on the type of solvent contained in the pump chamber.

Dependencies are inferred from the claim text.

Compensating temperature-induced errors during piston movement

Life of this patent

Compensating temperature-induced errors during piston movement

Life of this patent

Abstract

Claims12