Liquid feed pump and liquid chromatography device

Patent metadata

Field	Value
Publication number	US-11859600-B2
Application number	US-201917427754-A
Country	US
Kind code	B2
Filing date	Dec 3, 2019
Priority date	Mar 1, 2019
Publication date	Jan 2, 2024
Grant date	Jan 2, 2024

Abstract

A liquid feed pump which increases the liquid flow velocity in a stagnation area in the pressure chamber of a plunger pump, thereby improving the liquid replacement speed in the plunger pump. When the liquid in the liquid feed pump is replaced, a first plunger slides back and forth in the space between a lower limit point and an upper limit point, and the second plunger stops at least temporarily at a position near to the upper limit point or slides back and forth for a shorter distance than when the liquid feed pump usually feeds the liquid.

First claim

What is claimed is:

1. A liquid feed pump which sucks or discharges a liquid, comprising:
a first plunger pump which sucks or discharges the liquid by sliding of a first plunger;
a second plunger pump which sucks or discharges the liquid by sliding of a second plunger; and
a liquid replacement mechanism which replaces the liquid to be introduced into the liquid feed pump, wherein
the first plunger pump and the second plunger pump are connected in series in a channel in which the liquid moves,
the first plunger is structured to be able to move between a first lower limit point and a first upper limit point in the first plunger pump,
the second plunger is structured to be able to move between a second lower limit point and a second upper limit point in the second plunger pump,
in the second plunger pump, a second plunger seal for sealing between a main body of the second plunger pump and the second plunger is located at a position nearer to the second lower limit point than to the second upper limit point,
when the liquid in the liquid feed pump is replaced, the first plunger slides back and forth in a space between the first lower limit point and the first upper limit point, and
when the liquid in the liquid feed pump is replaced, the second plunger stops at least temporarily at a position nearer to the second upper limit point than to the second lower limit point or slides back and forth for a shorter distance than when the liquid feed pump sucks and discharges the liquid.

2. The liquid feed pump according to claim 1 , wherein
when the liquid in the liquid feed pump is replaced, the first plunger slides back and forth once in the space between the first lower limit point and the first upper limit point and then stops temporarily,
when the liquid in the liquid feed pump is replaced, while the first plunger slides back and forth in the space between the first lower limit point and the first upper limit point, the second plunger stops temporarily and while the first plunger stops temporarily, the second plunger slides back and forth between a space between the second lower limit point and the second upper limit point.

3. The liquid feed pump according to claim 1 , wherein when the liquid in the liquid feed pump is replaced, in a period in which the first plunger makes a sucking motion, the second plunger makes a discharging motion and in a period in which the first plunger makes the discharging motion, the second plunger makes the sucking motion.

4. The liquid feed pump according to claim 1 , wherein when the liquid in the liquid feed pump is replaced, in a period in which the first plunger makes a sucking motion, the second plunger makes the sucking motion and in a period in which the first plunger makes a discharging motion, the second plunger makes the discharging motion.

5. The liquid feed pump according to claim 1 , further comprising:
a suction path which introduces the liquid into the second plunger pump; and
a discharge path which discharges the liquid from the second plunger pump, wherein
a distance between the discharge path and the second lower limit point is larger than a distance between the suction path and the second lower limit point.

6. The liquid feed pump according to claim 1 , further comprising:
a suction path which introduces the liquid into the second plunger pump; and
a discharge path which discharges the liquid from the second plunger pump, wherein
a distance between the discharge path and the second lower limit point is equal to a distance between the suction path and the second lower limit point.

7. The liquid feed pump according to claim 6 , wherein the suction path and the discharge path are located at a position nearer to the second lower limit point than to the second upper limit point.

8. The liquid feed pump according to claim 1 , further comprising:
a suction path which introduces the liquid into the second plunger pump; and
a discharge path which discharges the liquid from the second plunger pump, wherein
a distance between the discharge path and the second lower limit point is smaller than a distance between the suction path and the second lower limit point.

9. The liquid feed pump according to claim 1 , wherein
when the liquid feed pump sucks and discharges the liquid, the first plunger pump slides back and forth between the first lower limit point and a position nearer to the first upper limit point than to the first lower limit point, and
when the liquid feed pump sucks and discharges the liquid, the second plunger pump slides back and forth between the second lower limit point and a position nearer to the second upper limit point than to the second lower limit point.

10. The liquid feed pump according to claim 1 , wherein
when the liquid feed pump sucks and discharges the liquid, the first plunger pump slides back and forth between the first upper limit point and a position nearer to the first lower limit point than to the first upper limit point, and
when the liquid feed pump sucks and discharges the liquid, the second plunger pump slides back and forth between the second upper limit point and a position nearer to the second lower limit point than to the second upper limit point.

11. The liquid feed pump according to claim 1 , wherein
the first plunger pump is connected to the liquid replacement mechanism, and
the second plunger pump discharges the liquid out of the liquid feed pump.

12. A liquid chromatography device comprising a liquid feed pump according to claim 1 .

Assignees

• Hitachi High Tech Corp

Inventors

• Tsukada Nobuhiro
• Akieda Daisuke
• Ito Shinya
• Nishiki Kenichiro

Classifications

• F04B1/34 Primary

  Control not provided for in groups F04B1/02, F04B1/03, F04B1/06 or F04B1/26 · CPC title

• F04B1/02

  having two cylinders (in V-arrangement F04B1/04) · CPC title

• F04B23/06

  the pumps being all of reciprocating positive-displacement type · CPC title

• F04B49/02

  Stopping, starting, unloading or idling control · CPC title

• F04B49/12

  by varying the length of stroke of the working members · CPC title