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US 7,063,785 B2Granted
Pump for liquid chromatography
AssigneeHitachi High-Technologies Corporation
InventorsKenji Hiraku, Kunihiko Takao, Hironori Kaji, Masahito Ito
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AssigneeHitachi High-Technologies Corporation
InventorsKenji Hiraku, Kunihiko Takao, Hironori Kaji, Masahito Ito
Estimating the term…
The invention provides a pump for liquid chromatography excellent in feeding liquid stably at an extremely low flow rate with high accuracy and in discharging bubbles at startup. At startup, a first plunger feeds solvent at a large flow rate to discharge bubbles in a pump and to fill the solvent into the pump in a short time and in a normal operation, the first plunger is stopped and the second plunger is pushed into a second pressure chamber at a low speed to feed the solvent at a low flow rate. When the second plunger reaches full stroke, the second plunger is pulled back at a high speed and at the same time the first plunger is pushed into a first pressure chamber in synchronization with the pullback of the second plunger to control the flow rate passing a discharge passage to a constant value at all times by a controller. Further, while the second plunger feeds the solvent, the first plunger is slightly pushed into the first pressure chamber to keep pressure in the first pressure chamber at pressure equal to or less than pressure in the second pressure chamber.
A pump for liquid chromatography comprising a pressure chamber communicating with an suction passage, a pressure chamber communicating with a discharge passage, and a first plunger and a second plunger that respectively reciprocate in the pressure chambers, wherein the first plunger is provided on an upstream side near to the suction passage and wherein the second plunger is provided on a downstream side near to the discharge passage,
A pump for liquid chromatography comprising a first pressure chamber communicating with an suction passage and a middle passage, a first plunger reciprocating in the first pressure chamber, a suction valve provided in the suction passage, a discharge valve provided in the middle passage, a second pressure chamber formed on a downstream side of the discharge valve and communicating with the middle passage and a discharge passage, and a second plunger reciprocating in the second pressure chamber,
Dependencies are inferred from the claim text.