U.S. patent application number 13/990754 was filed with the patent office on 2013-10-03 for chromatography pump.
This patent application is currently assigned to GE HEALTHCARE BIO-SCIENCES AB. The applicant listed for this patent is Jan Kranse, Mats Lundkvist, Bjorn Olovsson, Owe Salven. Invention is credited to Jan Kranse, Mats Lundkvist, Bjorn Olovsson, Owe Salven.
Application Number | 20130259723 13/990754 |
Document ID | / |
Family ID | 45092341 |
Filed Date | 2013-10-03 |
United States Patent
Application |
20130259723 |
Kind Code |
A1 |
Salven; Owe ; et
al. |
October 3, 2013 |
CHROMATOGRAPHY PUMP
Abstract
The invention relates to a chromatography pump, comprising a
cylinder (202, 402) in which a piston (204, 404) is arranged for a
reciprocating movement; a front element (208) provided with a
cylinder head area (210) which together with the cylinder (202,
402) and the piston (204, 404) defines a cylinder space (212); an
inlet valve (214) and an outlet valve (216) arranged in the front
element (208); an inlet channel (218) arranged in the front element
(208) between the inlet valve (214) and the cylinder head area
(210); an outlet channel (220) arranged in the front element (208)
between the cylinder head area (210) and the outlet valve (216).
The inlet channel (218) and outlet channel (220) extend in a
substantially straight direction, so that air bubbles (234) are
prevented from being trapped within the inlet and outlet channels
(218, 220).
Inventors: |
Salven; Owe; (Uppsala,
SE) ; Olovsson; Bjorn; (Uppsala, SE) ;
Lundkvist; Mats; (Uppsala, SE) ; Kranse; Jan;
(Ostervala, SE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Salven; Owe
Olovsson; Bjorn
Lundkvist; Mats
Kranse; Jan |
Uppsala
Uppsala
Uppsala
Ostervala |
|
SE
SE
SE
SE |
|
|
Assignee: |
GE HEALTHCARE BIO-SCIENCES
AB
Uppsala
SE
|
Family ID: |
45092341 |
Appl. No.: |
13/990754 |
Filed: |
November 24, 2011 |
PCT Filed: |
November 24, 2011 |
PCT NO: |
PCT/EP2011/070953 |
371 Date: |
May 30, 2013 |
Current U.S.
Class: |
417/559 ;
417/437 |
Current CPC
Class: |
F04B 53/06 20130101;
F04B 11/0033 20130101; F04B 53/16 20130101 |
Class at
Publication: |
417/559 ;
417/437 |
International
Class: |
F04B 53/16 20060101
F04B053/16 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 30, 2010 |
SE |
1051261-4 |
Claims
1. A chromatography pump, comprising a cylinder (202, 402) in which
a piston (204, 404) is arranged for a reciprocating movement along
an axis (248); a front element (208) provided with a cylinder head
area (210) which together with the cylinder (202, 402) and the
piston (204, 404) defines a cylinder space (212); an inlet valve
(214) and an outlet valve (216) arranged in the front element
(208); an inlet channel (218) arranged in the front element (208)
between the inlet valve (214) and the cylinder head area (210); an
outlet channel (220) arranged in the front element (208) between
the cylinder head area (210) and the outlet valve (216), wherein
the inlet channel (218) and outlet channel (220) extend in a
substantially straight direction, and in that the inlet channel
(218) and outlet channel (220) each extend obliquely to the axis
(248).
2. The pump of claim 1, wherein a cavity (242) is arranged adjacent
the cylinder space (212)and in that an inlet (244) of the outlet
channel (220) is arranged in the cavity (242).
3. The pump of claim 2, wherein an outlet (240) of the inlet
channel (218) is arranged in the cavity (242).
4. The pump of claim 2, wherein the cavity (242) has a form
substantially corresponding to an arch, so that air bubbles (234)
are prevented from being trapped within the cavity (242).
5. The pump of claim 1, wherein the front element (208) is made of
PEEK material, titanium or hastelloy.
6. The pump of claim 1, wherein the surface roughness (Ra) of the
walls (236) of the inlet and outlet channels (218, 220) is between
0.2-2.0, preferably between 1.0-2.0.
7. The pump of claim 1, wherein the surface roughness (Ra) of the
wall (238) of the cylinder head area (210) is between 0.2-2.0,
preferably between 1.0-2.0.
8. The pump of claim 1, wherein the inlet and outlet valves (214,
216) are check valves provided with seated balls (226) in which a
weight (303) arranged on the ball (226) urges the ball (226)
against the seat (228).
9. The pump of claim 1, wherein the cylinder head area (210) has a
normal (246) which substantially coincides with the axis (248) of
the piston (204).
10. The pump of claim 1, wherein the chromatography pump (201, 301,
401) is designed for pumping liquid (222).
11. The pump of claim 1, wherein a circumferential seal (405) is
arranged on the piston (404), and a circumferential leaf spring
(407) is arranged to apply an outwardly directed radial load on the
seal (405).
12. The pump of claim 11, wherein a tap (409) is arranged on an end
part (411) of the piston (404), which tap (409) is attached to the
piston (404) and fixates the seal (405) on the end part (411) of
the piston (404).
13. The pump of claim 1, wherein the outlet channel (220) and the
inlet and outlet valves (214, 216) extend in a substantially
coincident direction, so that the pump may be mounted with outlet
channel (220) in a substantially vertical direction in relation to
a horizontal plane (308).
Description
TECHNICAL FIELD
[0001] The present invention relates to a chromatography pump
according to the preamble of claim 1.
[0002] Chromatography is a chemical process for identifying and
quantifying compositions held in a sample and also for purification
and extraction of compositions. In the process, compositions in a
solution are separated from each other as the solution moves
through a stationary material held in a column.
[0003] The solution is pumped under high pressure through the
stationary material in the column by one or several chromatography
pumps.
BACKGROUND ART
[0004] In chromatography and especially in liquid chromatography
often only very small samples of the material to be analyzed or
purified are available. The process during mixing gradients of two
different liquids is also sensitive for rapid changes in the flow
and pressure of solution as it moves through the stationary
material in the column. For this reason the chromatography pump
system has to be very accurate in order to achieve a minimum of
fluctuation in flow output and pressure from the chromatography
pump.
[0005] In the preparation for the chromatography process air held
in the chromatography pump has to be removed. Also, air held in the
sample has to be removed. Therefore, chromatography pump systems
often are provided with a purging arrangement which removes the air
held in the chromatography pump in the beginning of the process.
The purging arrangement generates a vacuum at the outlet valve of
the pump, so that air held within the pump is sucked out from the
pump and the solution or sample simultaneously is sucked into the
pump.
[0006] However, to some extent air bubbles tend to be trapped
within the chromatography pump cylinder even if the purging
arrangement has removed the major volume of air held in the
chromatography pump. The air bubbles trapped within the
chromatography pump reduces the performance of the chromatography
pump, so that the pressure and flow of the solution will fluctuate.
This will influence on the overall chromatography mixing process,
so that less accurate results will be achieved.
[0007] In a chromatography pump available in the prior art, which
will be described in more detail below together with FIG. 1, air
bubbles tend to be trapped in the inlet and outlet channels of the
pump, and also in the cylinder. The air bubbles are trapped at
stagnant zones i.e. at edges and corners formed in the known
pump.
SUMMARY OF THE INVENTION
[0008] The object of the invention is to achieve a chromatography
pump with automatic purging, which eliminates manual means for the
purging operation.
[0009] Another object of the invention is to achieve a
chromatography pump which facilitates air bubbles to be transported
through the pump.
[0010] A further object of the invention is to achieve a
chromatography pump in which air bubbles are prevented to be
trapped.
[0011] A further object of the invention is to achieve a minimum of
fluctuation in flow output and pressure of a chromatography
pump.
[0012] These objects are achieved by a chromatography pump
according to claim 1.
[0013] Since the inlet channel and outlet channel extend in a
substantially straight direction there are no edges and corners
where air bubbles can be trapped within the channels. Instead the
air bubbles will pass through the cannels without influencing the
performance of the chromatography pump. Thus, a chromatography pump
with high performance is achieved.
[0014] According to an aspect of the invention an outlet of the
inlet channel arranged in the cylinder head area has a
substantially elliptic configuration. This configuration
facilitates air bubbles to be transported out of the inlet channel
and further to the outlet channel.
[0015] According to a further aspect of the invention a cavity is
arranged in the cylinder head area and an inlet of the outlet
channel is arranged in the cavity. Thereby, air bubbles coming from
the inlet channel and air bubbles in the cylinder will easily be
transported out to the outlet channel.
[0016] According to a further aspect of the invention the cavity
has a form substantially corresponding to an arch. This
configuration facilitates the transport of air bubbles out to the
outlet channel.
[0017] According to a further aspect of the invention the front
element is made of PEEK material, titanium or hastelloy. Thereby, a
high strength of the front element is achieved. Also, the surface
properties of these materials can be adapted to prevent air bubbles
to be trapped and tied on the surfaces in the channels and in the
cylinder.
[0018] According to a further aspect of the invention the surface
roughness (Ra) of the walls of the inlet and outlet channels and of
the wall of the cylinder head area are between 0.2-2.0, preferably
between 1.0-2.0. This will prevent air bubbles to be tied to the
surface of the inlet and outlet channels and of the wall of the
cylinder head area.
[0019] According to a further aspect of the invention the inlet and
outlet valves are check valves provided with seated balls in which
a weight arranged on the ball urges the ball against the seat.
Thereby, air bubbles are prevented from being trapped between the
ball and the seat due to the force from the ball on the seat. Also,
between the ball and the inner wall of the valve capillary forces
caused by air bubbles make the ball get stuck to the inner wall.
This is prevented by the weight arranged on the ball.
[0020] According to a further aspect of the invention the cylinder
head area has a normal which substantially coincides with the axis
of the piston. Thus, a compact design of the cylinder space is
achieved. Because the inlet and outlet channels are connected to
the cylinder head area and that the normal of the cylinder head
area substantially coincides with the axis of the piston air
bubbles in the cylinder will easily be transported out to the
outlet channel.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Further aspects, advantages and features of the invention
can be derived from the following detailed description of exemplary
embodiments of the invention, with reference to the drawings.
[0022] FIG. 1 shows a diagrammatic cross section view of a prior
art chromatography pump,
[0023] FIG. 2 shows a cross section view of a preferred embodiment
of a chromatography pump according to the invention,
[0024] FIG. 3 shows a front view of the preferred embodiment of the
chromatography pump according to the invention,
[0025] FIG. 4 shows a cross section view of a second embodiment of
a chromatography pump according to the invention,
[0026] FIG. 5 shows a cross section view of a third embodiment of a
chromatography pump according to the invention, and
[0027] FIG. 6 shows an enlarged cross section view of a forth
embodiment of a piston for a chromatography pump according to the
invention.
DETAILED DESCRIPTION
[0028] FIG. 1 shows a diagrammatic cross section view of a prior
art chromatography pump 101, which comprises a cylinder 102 in
which a piston 104 is arranged for a reciprocating movement. The
reciprocating movement of the piston 104 is generated by a driving
means 106, such as an electric motor. A front element 108 is
provided with a cylinder head area 110 which together with the
cylinder 102 and the piston 104 defines a cylinder space 112. An
inlet valve 114 and an outlet valve 116 in form of check valves are
arranged in the front element 108. An inlet channel 118 is arranged
in the front element 108 between the inlet valve 114 and the
cylinder head area 110, and an outlet channel 120 is arranged in
the front element 108 between the cylinder head area 110 and the
outlet valve 116. When the piston 104 moves in the left direction
in FIG. 1 a liquid 122 held in a schematically disclosed container
124 is sucked into the cylinder space 112 through the inlet valve
114 and the inlet channel 118 due to vacuum generated in the
cylinder space 112 by the piston 104. When the vacuum generated
sucks the liquid 122 through the inlet valve 114 a ball 126 within
the valve 114 lifts from a seat 128 by the flow of the liquid and
open a passage for the liquid 122 between the ball 126 and the seat
128. At the same time liquid 122 is prevented from entering the
outlet valve 116 because the ball 126 seals against the seat
128.
[0029] When the piston 104 thereafter changes direction and moves
in the right direction in FIG. 1 the liquid 122 is pressed out of
the cylinder space 112 through the outlet channel 120 and out of
the outlet valve 116 due to the pressure generated in the cylinder
space 112 by the piston 104. From the outlet valve 116 the liquid
flows to a schematically disclosed column 130 in which a stationary
material 132 is held. From the column 130 the liquid which has
passed the column 130 is led to a waste container 131 or a fraction
collector. When the pressure press the liquid 122 through the
outlet valve 116 the ball 126 within the valve 116 lifts from the
seat 128 by the flow of the liquid 122 and open a passage for the
liquid 122 between the ball 126 and the seat 128. At the same time
liquid 122 is prevented from escaping the inlet valve 114 because
the ball 126 seals against the seat 128.
[0030] However, air bubbles 134 tend to be trapped within the known
chromatography pump 101 disclosed in FIG. 1, especially in the
inlet and outlet channels 118, 120 of the pump 101, and also in the
cylinder space 112. One reason why the air bubbles 134 are trapped
in the inlet and outlet channels 118, 120 is that the channels 118,
120 are provided with stagnant zones, such as edges and corners
136. Another reason is that the surface roughness of the wall
surface of the channels are too smooth, which facilitates air
bubbles 134 to be tied to the surfaces. Similar drawbacks can be
found in the cylinder space 112 at the cylinder head area 110. Air
bubbles 134 can also be trapped between the ball 126 and the seat
128 in the inlet and outlet valves 114, 116. The trapped air
bubbles 134 can also prevent the ball 126 from returning back to
the seat 128 due to capillary forces.
[0031] As mentioned above the air bubbles 134 trapped within the
chromatography pump 101 reduces the performance of the pump 101, so
that the pressure and flow of the liquid 122 will fluctuate. This
will influence on the overall chromatography process, so that less
accurate results will be achieved.
[0032] FIG. 2 shows a cross section view of a preferred embodiment
of a chromatography pump 201 according to the invention. The
chromatography pump 201 comprises a cylinder 202 in which a piston
204 is arranged for a reciprocating movement along an axis 248. A
seal means 205 is arranged on the piston 204, so that leakage
between the piston 204 and the cylinder 202 is minimized. The
reciprocating movement of the piston 204 is generated by a driving
means 206, such as an electric motor. A front element 208 is
provided with a cylinder head area 210 which together with the
cylinder 202 and the piston 204 defines a cylinder space 212. An
inlet valve 214 and an outlet valve 216 in form of check valves are
arranged in the front element 208. An inlet channel 218 is arranged
in the front element 208 between the inlet valve 214 and the
cylinder head area 210, and an outlet channel 220 is arranged in
the front element 208 between the cylinder head area 210 and the
outlet valve 216. When the piston 204 moves in the left direction
in FIG. 2 a liquid 222 held in a schematically disclosed container
224 is sucked into the cylinder space 212 through the inlet valve
214 and the inlet channel 218 due to vacuum generated in the
cylinder space 212 by the piston 204. When the vacuum generated
sucks the liquid 222 through the inlet valve 214 a ball 226 within
the valve 214 lifts from a seat 228 by the flow of the liquid 222
and open a passage for the liquid 222 between the ball 226 and the
seat 228. At the same time liquid 222 is prevented from entering
the outlet valve 216 because the ball 226 seals against the seat
228. At the beginning of the pumping process the cylinder 202,
channels 218, 220 and valves 214, 216 are filled with air.
Therefore, during a certain period of time the air will be pumped
out of the cylinder 202, channels 218, 220 and valves 214, 216 by
the reciprocating movement of the piston 204. Thus, the
chromatography pump 201 according to the invention is self
purging.
[0033] When the piston 204 thereafter changes direction and moves
in the right direction in FIG. 2 the liquid 222 is pressed out of
the cylinder space 212 through the outlet channel 220 and out of
the outlet valve 216 due to the pressure generated in the cylinder
space 212 by the piston 204. From the outlet valve 216 the liquid
222 flows to schematically disclosed column 230 in which a
stationary material 232 is held. From the column 230 the liquid
which has passed the column 230 is led to a waste container 231 or
a fraction collector. When the pressure press the liquid 222
through the outlet valve 216 the ball 226 within the valve 216
lifts from the seat 228 by the flow of the liquid 222 and open a
passage for the liquid 222 between the ball 226 and the seat 228.
At the same time liquid 222 is prevented from escaping the inlet
valve 214 because the ball 226 seals against the seat 228. An
example of pressure and piston displacement of the chromatography
pump 201 according to the invention is 200 bar and 125 .mu.l. The
flow generated by the pump is in the range 0-60 ml/minute.
[0034] The inlet and outlet channels 218, 220 in FIG. 2 extend in a
substantially straight direction without or with as few sharp edges
or corners as possible, so that air bubbles 234 are prevented from
being trapped within the channels 218, 220. The channels 218, 220
are not provided with stagnant zones, such as edges and corners,
and therefore air bubbles 234 will not be trapped within the
channels. Instead the air bubbles 234 will pass through the cannels
218, 220 without influencing the performance of the chromatography
pump 201. In addition, the outlet channels extend obliquely to axis
248, as can be seen in the Figures. In other words, the outlet
channels 218 and 220, provide a substantially straight line
connection between the cylinder head area 210 and their respective
valves 214 and 216, and the straight lines are slanted relative to
the axis 248 of the piston 204, and have divergent paths. Thus,
with this arrangement of a chromatography pump 201, high
performance is achieved. The configuration of the channels 218 and
220 provides improved flow, and also facilitates the cleaning of
the pump 201. This is especially important when different liquids
are used in the pump 201. When changing liquids to be pumped it was
common in the prior art that air bubbles were trapped within the
pump. In the pump 201 according to the invention air bubbles 234
are unlikely to be trapped and the pump 201 will be purged
automatically.
[0035] The surface roughness (Ra) of the walls 236 of the inlet and
outlet channels 218, 220 and of the wall 238 of the cylinder head
area 210 are between 0.2-2.0, preferably between 1.0-2.0.
[0036] This will prevent air bubbles 234 to be tied to the wall 236
of the inlet and outlet channels 218, 220 and of the wall 238 of
the cylinder head area 210. The surface roughness can be achieved
by special machining techniques. The front element 208 is
preferably made of PEEK material, titanium or hastelloy. Other
materials are also possible. PEEK and hastelloy are registered
trademarks. Thereby, a high strength of the front element 208 is
achieved. Also, the surface properties of these materials can be
adapted to the above-mentioned surface roughness values. The liquid
222 must be pumped under high pressure through the stationary
material 232 in the column 230. Therefore, the materials used in
the front element 208 must have high strength properties.
[0037] FIG. 3 shows a front view of the preferred embodiment of the
chromatography pump 201 according to the invention. A cavity 242 is
arranged in the cylinder head area 210 and an outlet 240 of the
inlet channel 218 is arranged in the bottom part of the cavity 242.
Also, an inlet 244 of the outlet channel 220 is arranged in the
cavity 242. Thereby, air bubbles 234 coming from the inlet channel
218 and air bubbles 234 in the cylinder space 212 will easily be
transported out to the outlet channel 220. Preferably, the cavity
242 has a form substantially corresponding to an arch and the inlet
244 of the outlet channel 220 has conical form. This configuration
facilitates the transport of air bubbles 234 out to the outlet
channel 220. However, it is possible to arrange the outlet 240 of
the inlet channel 218 outside the cavity 242.
[0038] The cylinder head area 210 has a normal 246 which
substantially coincides with the axis 248 of the piston 204. Thus,
a compact design of the cylinder space 212 is achieved. Since the
inlet and outlet channels 218, 220 are connected to the cylinder
head area 210 and that the normal 246 of the cylinder head area 210
substantially coincides with the axis 248 of the piston 204 air
bubbles 234 in the cylinder 202 will easily be transported out to
the outlet channel 220.
[0039] FIG. 4 shows a cross section view of a second embodiment of
a chromatography pump 301 according to the invention. Similar
components as disclosed in FIG. 2 will have same reference numbers.
The inlet and outlet valves 214, 216 are provided with seated balls
226 in which weights 303 are arranged on the balls 226 that urges
the balls 226 against the seat 228. Thereby, air bubbles 234 are
prevented from being trapped between the ball 226 and the seat 228
due to the force from the ball 226 on the seat 228. Also, the ball
226 is prevented from being stuck to the inner wall of the valves
214, 216 due to capillary forces. The weights 303 are influenced by
gravity forces and therefore the pump 301 according to this second
embodiment has to be mounted in such a direction that the weights
303 rests on the balls 226 in the valves 214, 216. Instead or in
combination with the weight 303 it is also possible to arrange a
spring (not disclosed) in the valves 214, 216, which urges the ball
226 against the seat 228.
[0040] FIG. 5 shows a cross section view of a third embodiment of a
chromatography pump 301 according to the invention. Similar
components as disclosed in FIG. 3 will have same reference numbers.
According to this embodiment the outlet channel 220 and the inlet
and outlet valves 214, 216 extend in a substantially coincident
direction, so that the pump 301 may be mounted with outlet channel
220 in a substantially vertical direction in relation to a
horizontal plane 308. As a result air bubbles 234 within the pump
301 will easy leave the outlet channel 220, because of the
gravitation influencing on the air bubbles 234 in the liquid.
[0041] FIG. 6 shows an enlarged cross section view of a forth
embodiment of a piston 404 for a chromatography pump 401 according
to the invention. The piston 404 is provided with a circumferential
seal 405 which in a direction radial outwardly is spring loaded by
a circumferential leaf spring 407, so that a tight seal between the
cylinder 402 and the piston 404 is achieved. A tap 409, preferably
made of titanium is arranged on the end part 411 of the piston 402.
The tap 409 is attached to the piston 404 and fixates the seal 405
on the end part 411 of the piston 404.
[0042] The chromatography pump 201, 301, 401 according to the
present invention is primary designed for pumping liquid 222.
However, other fluids may also be pumped by the chromatography pump
201, 301, 401 according to the invention.
* * * * *