Control arrangement for controlling a piston pump unit for liquid chromatography

Patent metadata

Field	Value
Publication number	US-9624923-B2
Application number	US-201313917963-A
Country	US
Kind code	B2
Filing date	Jun 14, 2013
Priority date	Jun 19, 2012
Publication date	Apr 18, 2017
Grant date	Apr 18, 2017

Abstract

A control arrangement for controlling a piston pump unit for liquid chromatography, in particular high-performance liquid chromatography, is described. The piston pump unit has at least two piston-cylinder units which operate cyclically in a phase-offset manner and generate, at an outlet port, a predetermined flow of a liquid medium to be delivered. A system pressure is established at the outlet port, irrespective of an associated fluid load resistance. The control arrangement is configured to record the pressure in the cylinder volume of at least a first of the at least two piston-cylinder units. During a measurement phase of the compression phase of the first piston-cylinder unit or during a measurement phase of the decompression phase of the first piston-cylinder unit, the control arrangement stops the drive device for the first piston-cylinder unit for a predetermined time period and in the process records measurement data which characterize the time profile of the pressure.

First claim

What is claimed is:

1. A piston pump unit for liquid chromatography comprising:
(a) at least two piston-cylinder units configured to generate, at an outlet port, a predetermined flow of a liquid medium at a system pressure, in which each piston-cylinder unit has an independent drive device,
(b) a control device configured to
(i) control the independent drive devices for the at least two piston-cylinder units,
(ii) compress the liquid medium in a first cylinder of the at least two piston-cylinder units in a compression phase from a starting pressure to the system pressure,
(iii) decompress the first cylinder of the at least two piston-cylinder units in a decompression phase,
(iv) record pressure values as a function of time in a cylinder volume of at least a first of the at least two piston-cylinder units during a measurement phase,
(v) stop the independent drive device for the first piston-cylinder unit for a predetermined time period during the measurement phase, the measurement phase being either a measurement phase of the compression phase of the first piston-cylinder unit or a measurement phase of the decompression phase of the first piston-cylinder unit;
(vi) determine a correction dependence to correct a piston movement of at least one of the at least two piston-cylinder units during a compensation phase based on the recorded pressure values as a function of time, and
(vii) control the at least one of the at least two piston-cylinder units using the correction dependence during the compensation phase.

2. The piston pump unit of claim 1 , in which the at least two piston-cylinder units are further configured to operate cyclically in a phase-offset manner.

3. The piston pump unit of claim 1 . further comprising: a pressure sensor configured to measure the pressure values in the cylinder volume of at least a first of the at least two piston-cylinder units.

4. The piston pump unit of claim 1 , in which the correction dependence is further based on a compression coefficient, a pressure value and a time value when the compressing or decompressing of the first cylinder is stopped, and another time value at a start of the compensation phase.

5. The piston pump unit of claim 4 , in which the compression coefficient is a ratio of a change in pressure values to an associated travel distance of a piston in the first cylinder of the at least two piston-cylinder units.

6. The piston pump unit of claim 5 , in which the control device is further configured to
(vii) calculate the compression coefficient using a compression coefficient equation, the compression coefficient equation comprising:
Q c =Δs/ΔP,
where Q c is the compression coefficient, and ΔP is the change in the pressure values for the associated travel distance Δs of the piston in the first cylinder of the at least two piston-cylinder units.

7. The piston pump unit of claim 6 , in which the control device is further configured to
(viii) calculate the correction dependence using a correction dependence equation for piston movement, the correction dependence equation for piston movement comprising:

s
corr

⁡

(
t
)

=

-

Q
C

·

(

P
M

-

P
e

)

·

(

ⅇ

-

t
-

t
3

τ

-

ⅇ

-

t
5

-

t
3

τ

)

,

where s corr (t) is the correction dependence, t is a time value, Q c is the compression coefficient, P M is a pressure at a time t 3 in which the measurement phase starts, t 5 is a time in which the compensation phase starts, and P e and τ are both parameters.

8. The piston pump unit of claim 1 , in which the control device is further configured to calculate parameters P eD and τD of the correction dependence, where the measurement phase occurs during the decompression phase, using a pressure measurement equation and the recorded pressure values as a function of time, the pressure measurement equation comprising:

P
tmess

⁡

(
t
)

=

P
MD

+

(

P
eD

-

P
MD

)

·

(

1
-

ⅇ

-

t
-

t
21

τ
D

)

where P tmess ,(t) is the recorded pressure values as

Assignees

• Ruegenberg Gervin
• Schloderer Richard
• Tuchan Werner
• Dionex Softron Gmbh

Inventors

• Ruegenberg Gervin
• Schloderer Richard
• Tuchan Werner

Classifications

• F04B23/06

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

• F04B49/22 Primary

  by means of valves (F04B49/03 takes precedence) · CPC title

• G01N2030/326

  pumps · CPC title

• G01N30/22

  in high pressure liquid systems · CPC title

• G01N30/32

  of pressure or speed (G01N30/36 takes precedence) · CPC title