| 摘要 |
To deliver a fluid by a pump chamber (14) and piston (12), the piston length is set to give the pressure within the pump chamber to deliver a precise volume. Also claimed is an appts. with a system to determine the movement length required for a given compression by the piston. To determine the piston stroke length, for the required compression, the Hall effect is used to register the compression development with communication between the pump chamber (14) and a delivery channel (20). The piston speed is controlled during delivery, as a function of the compression stroke length. The piston (12) speed is modified at least once during delivery, as a function of the fluid pressure downstream of the pump chamber. Before the end of the decompression stroke, a value is calculated for the point where the end of the action occurs. A valve is opened, under control. to link the pump chamber (14) with a fluid source, as a function of the pending value. When using two pump chambers (14) in parallel in a fluid circuit, each has a piston with independent control. The pistons (12) are controlled so that a piston builds up a pressure in one chamber while the other piston delivers a fluid vol., and remains static until it makes a further delivery. With simultaneous piston control, the start of delivery is triggered for one piston (12) and the start of a terminal delivery phase by the other piston. The fluid is for chromatographic analysis, and can be a mixture of two fluids.
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