U.S. patent application number 10/383954 was filed with the patent office on 2003-10-16 for diaphragm pump.
This patent application is currently assigned to Bayer Aktiengesellschaft. Invention is credited to Jahn, Peter, Krumbach, Bernhard.
Application Number | 20030194332 10/383954 |
Document ID | / |
Family ID | 28051271 |
Filed Date | 2003-10-16 |
United States Patent
Application |
20030194332 |
Kind Code |
A1 |
Jahn, Peter ; et
al. |
October 16, 2003 |
Diaphragm pump
Abstract
A diaphragm pump with a multi-part pump body is described. The
pump consists at least of three rigid plates (201, 203, 205) and at
least two elastic diaphragms (204, 202) arranged between these
plates (201, 203, 205), the plates (201, 203, 205) forming, in
particular, a pumping chamber (211) and at least two shut-off
chambers (210, 212), in each case with an inlet (240) and an outlet
(241) orifice for the conveyable material, and the pumping chambers
(211) and shut-off chambers (210, 212) forming, together with an
inlet duct (207), the connecting ducts (208) and (209) and an
outlet duct (206), a passage duct, the pumping chamber (211) and
the shut-off chambers (210, 212) being separated by the diaphragms
(204, 202) in each case into a product space (230, 231, 232) and a
control space (220, 221, 222), and the control spaces (220, 221,
222) having control lines (119, 120, 121) which are connected to a
control unit (100, 115).
Inventors: |
Jahn, Peter; (Leverkusen,
DE) ; Krumbach, Bernhard; (Leverkusen, DE) |
Correspondence
Address: |
WILLIAM GERSTENZANG
NORRIS, MCLAUGHLIN & MARCUS, P.A.
220 EAST 42ND STREET, 30TH FLOOR
NEW YORK
NY
10017
US
|
Assignee: |
Bayer Aktiengesellschaft
Leverkusen
DE
|
Family ID: |
28051271 |
Appl. No.: |
10/383954 |
Filed: |
March 7, 2003 |
Current U.S.
Class: |
417/395 ;
417/507 |
Current CPC
Class: |
F04B 43/0733
20130101 |
Class at
Publication: |
417/395 ;
417/507 |
International
Class: |
F04B 043/06 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 12, 2002 |
DE |
10216146.1 |
Claims
We claim:
1. A diaphragm pump comprised of at least three plates, one of
which is a middle plate (203) and two of which are outer plates
(201, 205), the middle plate being disposed between the two outer
plates, said at least three plates forming at least one pumping
chamber (211), at least two shut-off chambers, said at least two
shut-off chambers being a first shut-off chamber (210) and a second
shut-off chamber 212), each of said pumping and shut-off chambers
being in the form of a spherical segment, a spherical zone, a
cylinder or a truncated cone; said middle plate being separated
from each of said outer plates by two diaphragms (202, 204) which
diaphragms also divide said pumping and shut-off chambers into
control spaces (220, 221, 222) and product spaces (230, 231, 232),
the product space (231) of the pumping chamber being connected to
the product space (230) of said first shut-off chamber (210) by a
first connecting duct (208) having an orifice (241) opening into
said pumping chamber, and to the product space (232) of said second
shut-off chamber (212) by a second connecting duct (209) having an
orifice (243) opening into said second shut-off chamber, with an
outlet duct (206) connected to the product space (232) of second
shut-off chamber (212) through an outlet orifice (244), an inlet
duct (207) connected to the product space of first shut-off chamber
(210) through an inlet orifice (240); said pumping chamber (211)
and shut-off chambers (210, 212), together with outlet duct (206)
and inlet duct (207), first connecting duct (208) and second
connecting duct (209) forming a passage duct through said pump,
said control spaces (220, 221, 222) being connected to a control
unit (100, 115) by control lines (119, 120, 121).
2. Diaphragm pump according to claim 1, wherein the pump has in
product space (231) a groove (213) which runs form the vertex of
said product space to the outlet orifice.
3. Diaphragm pump according to claim 1 wherein pumping chamber
(211) the shut-off chambers (210, 212) are sealed off at their
edges by the diaphragms (204, 202).
4. Diaphragm pump according to claim 1, wherein the diaphragms
(204, 202) consist of an elastic material selected from the group
consisting of elastomers, silicones, Viton.RTM. fluroroelastomer,
Teflon.RTM. polytetrafluoro-ethylene or an EPDM rubber.
5. Diaphragm pump according claim 1, wherein shut-off chambers
(210, 212) share a common diaphragm (202).
6. Diaphragm pump according claim 1, wherein the pump consists of
three plates and the pumping chamber (211) and shut-off chambers
(210, 212) are formed by depressions (210', 211', 212') in the
three plates (201, 203, 205).
7. Diaphragm pump according to claim 6, wherein the pump consists
of three plates and the pumping chamber (211) and shut-off chambers
(210, 212) are formed by depressions (210', 211', 212') in a middle
plate (203').
8. Diaphragm pump according to claim 6, wherein the pump consists
of three plates (201, 203, 205) and the pumping chamber (211) and
shut-off chambers (210, 212) are formed by depressions (210", 211",
212") in the outer plates (201", 205").
9. Diaphragm pump according to claim 1, wherein the
center-to-center distance between the respectively adjacent inlet
and outlet of the pumping chamber (211) or of the shut-off chambers
(210, 212) is at least twice to ten times the largest hydraulic
diameter of said inlet or outlet.
10. Diaphragm pump according to claim 1 the control spaces are
adapted to be operated by air or hydraulic fluid.
11. Diaphragm pump according to claim 1, further comprising a
connecting line which connects the inlet duct (207) and the outlet
duct (206) and is provided with an overflow valve.
12. Diaphragm pump according to claim 1, wherein the plates (201,
203, 205) are releasably held in their positions with respect to
one another.
13. Diaphragm pump according to claim 1, wherein the wall of at
least one of the control spaces (220, 221, 222) which is located
opposite the diaphragm (202, 204) has a compensating volume in the
form of a depression.
14. Diaphragm pump according to claim 13, wherein said at least one
control space is the control space (221) of the pumping chamber
(211) and said compensating volume is at most 100% of the
associated volume of the product space (231) of said pumping
chamber 211.
15. Diaphragm pump according to claim 1, wherein the projections of
the outer contours of the shut-off chambers overlap the outer
contours of pumping chambers.
16. Diaphragm pump according to claim 1, wherein the connecting
ducts between the pumping chamber (211') and the shut-off chambers
(210', 212') have a ratio of duct length to hydraulic diameter of
at most 20.
17. A pump set, consisting of two or more diaphragm pumps of claim
1, wherein the diaphragm pumps have a common control unit (100,
115).
18. Pump set according to claim 17, wherein said at least two
diaphragm pumps have common continuous plates (201, 203, 205).
19. Diaphragm pump according to claims 14, wherein said
compensating volume is at most 20% of the volume of said product
space.
20. Diaphragm pump according to claim 19, wherein said compensating
volume is at most 10% of said volume of said product space.
21. Diaphragm pump according to claim 16, wherein said ratio is at
most 10.
22. Diaphragm pump of claim 22, wherein said ratio is at most 5.
Description
BACKGROUND OF THE INVENTION
[0001] In chemical research laboratories, chemical reactions are
carried out in 100-ml glass vessels. For reactions of this kind,
the additional outlay in terms of apparatus and therefore the costs
of the apparatus for a test set-up must be kept as low as possible.
For a continuously, or even discontinuously, operating test
installation, metering and conveying pumps are required, which are
capable of metering small substance quantities within the range of
less than 1 ml per minute in a very compact and reproducible manner
and so as to be insensitive to blockage. In the laboratories,
different reactions are carried out at short time intervals, and
consequently the test conditions and also the chemicals used
change, so that a large number of substances with different
properties must, if possible, be metered accurately by means of one
type of pump. The metering accuracy of the pumps is defined
essentially by the short-term accuracy. In this case, the
substances to be metered must be metered reproducibly at short time
intervals (seconds or minutes) with a low degree of error.
[0002] In particular, known piston or diaphragm pumps are used for
tasks of this kind. These pump types are oscillating
positive-displacement pumps. These pumps operate on the
positive-displacement principle and are equipped with non-return
valves (i.e., "check valves") on the pump suction and delivery
sides. A change in metering quantity is carried out by a variation
in the piston or diaphragm stroke, so that a changed clearance
volume occurs in the pump head, depending on the set stroke. The
non-return valves exert a critical influence on the pumping
function and the metering accuracy of the pumps.
[0003] This leads to a reproducible metering of the smallest
possible liquid quantities being dependent directly on the
operating capacity of the pump valves which are in contact with the
product. The opening and closing functions of the valves are
dependent on the density and viscosity of the substance to be
conveyed, and therefore a reproducible and substance-independent
closing and opening are not ensured, and metering deviations occur,
particularly within small time segments (short-term accuracy).
Furthermore, the travel of the closing body in the non-return
valves is non-linear, and where, for example, a spherical closing
body is used, the spherical closing body executes a wobbling
movement until it becomes seated in the sealing seat and shuts off
the passage of substance. It is known that preferably ball-type
non-return valves are used in piston and diaphragm pump heads. The
change in the pumping capacity is carried out by a variation in the
stroke, so that the pistons or diaphragms no longer cover the
maximum stroke travel and the suction behaviour is thereby also
impaired.
[0004] In particular, in the metering of liquid substances having
different viscosities and/or densities, the closing time of the
non-return valves is affected by the viscosity and density, thus
leading to an increase in the metering error.
[0005] The known piston and diaphragm pumps are driven via gear
units by means of a camshaft or eccentric shaft. The direct
coupling of these pumps to drive units leads to large appliance
dimensions, the form of construction of which is too large for many
miniaturized test installations. The mechanical drives must be
manufactured with high precision, which also increases the
investment costs. Pulsating positive-displacement pumps are also
equipped with magnetic drives. As a result, the structural
dimensions of these pump types are slightly smaller and the pumps
have a constant clearance volume in the pump head.
[0006] Microsystem pumps, by means of which very small liquid
quantities can be conveyed, are known. Micropumps are what may be
referred to as precision pumps, the functioning of which is no
longer ensured when there is the least possible product-side
contamination. The flow ducts and positive-displacement spaces
within the micropump heads possess dimensions on the order of a few
micrometers. Contaminated products quickly block flow ducts or jam
the dynamically moved pump parts, so that a metering operation can
be quickly interrupted. Small product ducts are not suitable for
conveyance and metering of viscous substances, because the pressure
loss is too great.
[0007] Various diaphragm-type micropumps are known, which have very
small structural dimensions on account of piezoelectric or
thermopneumatic drives and can thereby meter small substance
quantities. The patent specification DE 4 402 119 C2 (corresponding
to U.S. Pat. No. 5,725,363) describes a diaphragm-type micropump
which is likewise driven thermally. These drive systems always
function on the principle of a thermally initiated volume expansion
on one diaphragm side, so that the conveying diaphragm of the pump
generates a pumping action as a result of the deflection.
Relatively high differential pressures cannot be overcome by means
of these drive systems, for example in order to meter a liquid
substance into a container which is under higher pressure.
Moreover, these pumps are susceptible to blockage, so that
operational use in chemical laboratories is not satisfactory and
pumps of this kind are not used in preparatory chemical
laboratories.
[0008] Microsystem pumps, which may be referred to as toothed-ring
pumps, operate at high rotational speeds and generate a pressure in
an annular gap. During the pressure build-up in the discharge
region of the pump, a backflow into the suction region takes place,
in particular because of the mechanical tolerances of the rotor and
stator of the pump, so that the pump efficiency is greatly reduced.
As a rule, the reproducible metering of low-viscosity substances
against a high pressure is not ensured due to the low drive power
of microsystem pumps.
[0009] The object on which the invention is based is, therefore, to
develop a pump which is highly miniaturized, conveys small volume
quantities, for example of 5 .mu.l to 1000 .mu.l/stroke and per
unit time, and possesses high short-term metering accuracy. The
pump is to have a good suction behavior and to convey counter to
pressure, so that, even in the non-flooded state of the pump head,
conveyance counter to pressure is possible. The metering of
substances of different density is not to have any appreciable
influence on the conveying accuracy and the metering behavior. The
fault susceptibility to blockage by product impurities is to be
substantially reduced, so that additional fine filters on the
suction side of the pump are not needed. Necessary suction and
delivery valves of the pump head are to open and close
reproducibly, independently of density and/or viscosity, and, in
particular, be leak-tight to gas pressure when closed; so that,
during pumping, no backflow takes place, high efficiency is
achieved and accurate pumping counter to pressure thereby becomes
possible. The metering capacity of the volume flows to be conveyed
must be adjustable or variable in a simple way and is to amount
from 5 to 100.000 .mu.l/stroke preferred from 10 to 10.000
.mu.l/stroke and especially preferred from 10 to 10 00
.mu.l/stroke. The pump is to be capable of being produced
cost-effectively from various resistant materials, particularly
because of different corrosion requirements in the chemical
industry. In view of the occasionally rough operating conditions
that the pump may be exposed to, the pump should be capable of
simple and cost-effective repair and maintenance.
[0010] Furthermore, investment benefits, as compared with the prior
art, are to become clearly apparent. The design of the control or
drive technology is not to exert any influence on the pump-head
size and on the possibility of integration into a miniaturized test
installation set-up. The pump is to be constructed in a modular
manner, so that the metering pump can be modified in a simple way
by corresponding additions or the exchange of module parts. Is
should be possible to change the metering capacity without the
positive-displacement travel of the diaphragm or piston in the pump
head increasing the clearance volume, so that the sucked-in liquid
volume is displaced out of the pump head completely at any
time.
SUMMARY OF THE INVENTION
[0011] The object is achieved, according to the invention, by means
of a pneumatically driven pump head which is constructed in a
modular lamella manner and which consists of at least three rigid
lamellae (plates), and, in the region of the individual parting
plane of the middle plate and of the respectively contiguous
adjacent plates, there is at least one concave depression, and each
depression is covered completely by an elastic diaphragm and the
diaphragm is on one side part of the product space of the pump and
at the other side part of the control space. The depressions on one
side or on both sides of the diaphragm establish the maximum travel
by which the elastic diaphragm can be deflected.
DETAILED DESCRIPTION
[0012] The subject of the invention is a diaphragm pump with a
multi-part pump body, comprising at least three rigid plates and in
each case an elastic diaphragm arranged between these plates, the
plates forming at least one pumping chamber and at least two
shut-off chambers, in particular in a three-dimensional form of a
truncated spherical segment of a spherical zone (cap), cylinder or
cone, in each case with an inlet and an outlet orifice for the
conveyable material, and the pumping and shut-off chambers being
connected to one another via connecting ducts, and, together with
an inlet duct, the connecting ducts and an outlet duct, forming a
passage duct, characterized in that the pumping and shut-off
chambers are divided by the diaphragms in each case into a product
space and a control space, and the control spaces have control
lines which are connected to a control unit.
[0013] In the case of pneumatic activation, the control space is
connected, in particular, via a duct which passes through the
respective outer plate, to, for example, an electropneumatic
control unit which has, for example, a vacuum generator in a
secondary line, in order to enable alternating pressure or vacuum
loading of the control space. It is also possible to use a
hydraulic fluid for the pressure and draught loading of the control
space. According to a control program which has at least four
control steps proceeding in succession, each with an associated
timer, for example, the diaphragms are deformed into the pumping
and shut-off chambers, so that the volume of the control space or
the product space is alternately increased and reduced. The
diaphragm simultaneously opens or closes the inlet and outlet
orifices of the chambers, said inlet and outlet orifices lying in
the diaphragm region, so that, during the closing operation, at
least the feed ducts which are in contact with the product are
sealingly closed and, in the case of a predetermined control, at
least one of the diaphragms lying in the direction of flow
generates a reproducible volume displacement. The control unit is
arranged decentrally, particularly, to facilitate the degree of
miniaturization, and, in the case of a pneumatic control, is
connected to the pump head, for example, by means of flexible
hoses.
[0014] By a "control unit" is meant here a combination of
electronic control and actuators, for example electropneumatic
switching valves, which are mounted on a compressed-air/vacuum
distributor which has a pneumatic vacuum generator located in a
secondary line. The electronic control and the actuators may be
mounted, for example, together in a housing. The electropneumatic
valves are operated by means of a control program, in order to
carry out an exact sequence of work steps for the pumping
operation.
[0015] In particular, the shut-off and pumping chambers are sealed
off at the edge by means of the inserted and compressed
diaphragms.
[0016] In a preferred version, each shut-off and pumping chamber
has an individually assigned diaphragm and the diaphragms are
inserted between the plates. By, for example, the plates being
screwed together, the diaphragms are clamped in, in order to close
the pressure-loaded control and product spaces sealingly relative
to the outside in the parting planes of the plates.
[0017] The clamping-in of the diaphragms between the plates has
advantages for the user in the event of repairs, so that, if the
pump head has a possible defect, only the small part-diaphragm has
to be exchanged and considerable material costs are saved.
Assignment of the part-diaphragm to the respective chamber allows
standardized diaphragm manufacture and reduces the manufacturing
costs.
[0018] A preferred embodiment of the pump has, at least in the
product space of the pumping chamber, a groove which connects the
vertex of the pumping chamber to the outlet orifice of the pumping
chamber.
[0019] The connecting groove from the vertex to the outlet orifice
of the pumping chamber increases the accuracy and reproducibility
of the conveying operation, in that a complete outflow of the
metering volume is ensured. The groove forms a discharging
collecting duct for the meterable material and compensates for
differences in deformation of the elastic diaphragm. Between the
inlet of the chamber and the groove there must be a surface
present, so that the diaphragm can seal off the inlet orifice of
the chamber in relation to the groove. The groove may, in the
simplest version, be an elongate duct, but the groove may also have
a branched contour in the depression.
[0020] In a further preferred embodiment of the pump, the control
pressure on the diaphragm can be set in all the control spaces at
least 0.1 bar higher than the prevailing pressure at the outlet
duct, preferably the control pressure is at least 0.5 bar higher
and, particularly preferably, the control pressure is 1 bar higher
than the pressure at the outlet duct.
[0021] The higher differential pressure between the outlet duct and
the control-side pressure ensures the leak-tight closing of the
respective inlet orifices in the chambers by the diaphragm.
[0022] The diaphragms consist preferably of elastic material, in
particular an elastomer, silicone, Viton.RTM. fluoroelastomer,
Teflon.RTM. polytetraethylene or an EPDM rubber.
[0023] A preferred version of the pump in which a plurality of
shut-off chambers have a common diaphragm is particularly
advantageous.
[0024] A preferred version of the diaphragm pump is characterized
in that the pump consists of at least three plates and the pumping
and shut-off chambers are formed by depressions in the plates.
[0025] In a particularly preferred form of construction, the pump
consists of at least three plates and the pumping and shut-off
chambers are formed by depressions in a middle plate.
[0026] Another particularly preferred form of the diaphragm pump is
characterized in that the pump consists of at least three plates
and the pumping and shut-off chambers are formed by depressions in
the outer plates.
[0027] In a preferred embodiment, that wall of the control space
which is located opposite the diaphragm has, at least in the
pumping chamber, a compensating volume, in particular a large-area
depression, into which the diaphragm fits when there is a vacuum in
the control space.
[0028] In a particularly preferred embodiment of the diaphragm
pump, the compensating volume is at most 100% of the respective
associated product-space volume, preferably the compensating volume
is at most 20% and, particularly preferably, the compensating
volume is at most 10% of the product-space volume.
[0029] Typically, the product spaces of the shut-off chambers are
made smaller than the product space of the pumping chamber.
[0030] The center-to-center distance between the respectively
adjacent inlet and outlet of each pumping or shut-off chamber is
twice to ten times the largest hydraulic diameter of the respective
inlet or outlet orifice, preferably the center to center distance
is twice to five times and, particularly preferably, twice to three
times.
[0031] The defined center-to-center distance is an important
functional dimension of the chambers. It ensures a leak-tight
closing of the feeding and discharging ducts or orifices and
increases the reproducible conveyance of gaseous or liquid
substances and has an influence on the degree of
miniaturization.
[0032] In a preferred version, the connecting ducts between the
pumping chamber and the shut-off chambers are made straight and
have a ratio of duct length to the respective hydraulic diameter of
the ducts of at most 20, preferably at most 10, particularly
preferably at most 5.
[0033] The small clearance volume between the pumping and shut-off
chambers improves the suction capacity of the pneumatic pump.
[0034] The plates of the diaphragm pump are connected preferably
releasably to one another for cleaning and repair purposes.
[0035] A decentral electropneumatic control unit preferably also
allows a synchronous activation of a plurality of pump heads, so
that, when a plurality of pumps are operating in parallel, only one
control unit is necessary.
[0036] By means of the diaphragm pump according to the invention,
with a decentral electropneumatic control unit, efficient use, at
the same time with low investment costs, is possible in the
research sector. This becomes clear particularly when changing set
tasks require conveying flows of different size which cannot be
covered by one type of pump head. In the case of conveying flows of
different size, only the pump head has to be exchanged, whereas the
control part remains unchanged. The exchange of the pump head is
carried out simply by the pneumatic control lines being
unclamped.
[0037] The control for conveyance by means of the diaphragm pump is
preferably to be carried out in such a way that a conveying stroke
consists of at least four individual successive control steps, and
each individual control step is separated from the subsequent
control step by means of an intermediate constant or variable
timer, and the conveying or metering capacity of the pump can be
varied by the variation of at least one timer.
[0038] The timers introduced between the control steps ensure that
the pneumatically triggered part-steps of the pumping stroke are
carried out exactly and completely and the individual steps proceed
reproducibly. The synchronous variation of all the timers for
regulating the conveying capacity ensures a simple
operator-friendly handling of the pump.
[0039] The timers belonging to the control are T from 0.1 seconds
to 100 seconds, preferably the range is T from 0.3 seconds to 30
seconds and, particularly preferably, the timer is T from 0.5
seconds to 10 seconds.
[0040] Those timers ensure that the rapid electronic control
signals (signal transit time) are not discontinued prematurely
before the slower pneumatic operations for deflecting the
diaphragms and the even more slower hydraulic positive-displacement
operations on that side of the diaphragm which is in contact with
the product are not completed. In particular, when viscous
substances are conveyed, the fluid-dynamic operations require more
time than the electronically triggered signals of the control.
[0041] The metering cycle consists preferably of at least four
control steps and has at least two different timers, of which only
one timer is variable and is used for regulating the pump
cycle.
[0042] To optimize the pumping cycle of a pump according to the
invention, the pneumatic opening and closing operations of the
diaphragms in the shut-off chambers may be provided with a
non-adjustable smaller timer and a variable timer may be used for
the OPEN/SHUT switching of the middle larger pumping chamber.
[0043] Two different timers are advantageous particularly when the
volume of the shut-off chambers is smaller than the volume of the
pumping chamber.
[0044] In a particularly preferred mode of operation, the time of
each timer is greater than the required switching time of the
assigned electropneumatic multi-way valves.
[0045] Preferably at least two diaphragm pumps are connected in
parallel to the electronic and the electropneumatic control
unit.
[0046] One electropneumatic control unit can activate a plurality
of diaphragm pumps in parallel, so that the pumps, if appropriate
having pump chambers of different size, can synchronously meter
various substances in different quantities simultaneously.
[0047] The thickness of the elastic diaphragm is preferably greater
than 0.1 mm and less than 5 mm and the height of the pumping and
shut-off chamber in the region of the vertex of the chamber
(greatest extent above the diaphragm) is, in particular, greater
than twice the diaphragm thickness and less than 10 times the
diaphragm thickness.
[0048] The concave depressions in the plates may have different
geometric shapes, such as, for example, that of a cylinder, of a
spherical segment or of a cone frustum. The diaphragm pump
preferably has smaller depressions for the suction-side and
delivery-side shut-off chamber than for the pumping chamber, and
all the depressions are arranged completely on the product side of
the diaphragm side in the middle plates.
[0049] A variant of the diaphragm pump consists preferably of a
pneumatically controlled pumping chamber, combined with two
magnetically operated valves as shut-off chambers.
[0050] The diaphragms inserted in the pump are designed preferably
with a diameter at least 20% larger than the formed diameter of the
chambers in the parting plane of the plates.
[0051] In a further alternatively preferred embodiment, metallic
diaphragms are used as the pump diaphragm and are inserted or are
connected unreleasably by welding to one of the part-plates, in
particular an outer plate.
[0052] In a further preferred embodiment, a pulsation damper is
mounted downstream of the delivery-side shut-off chamber in the
direction of flow, in particular in the region of the outlet duct
of the diaphragm pump.
[0053] In a further particular embodiment, the diaphragm pump is
equipped with an integrated spring-loaded overflow valve, in order
to generate an internal product circulation in the diaphragm pump.
If the connected control pressure is higher than the desired pump
pressure, an integrated expansion possibility from the pump
delivery side to the pump suction side is provided.
[0054] In a further particularly preferred version, at least two
pump units, consisting of two pumping chambers with four associated
shut-off chambers, to form a double diaphragm-pump head, are
arranged in the three rigid plates.
[0055] The subject of the invention is also a pump set consisting
of two or more diaphragm pumps, the diaphragm pumps according to
the invention having a common control unit.
[0056] A pump set in which the diaphragm pumps have common
continuous plates is preferred.
[0057] By reason of the diaphragm pump according to the invention,
with an activatable section and delivery valve or with a
suction-side and delivery-side shut-off chamber, depending on the
design size, very small volume flows of <5 .mu.l/stroke into the
ml range per minute can be conveyed reproducibly. The separate
set-up between the actual pumping unit or pump head and the
decentral electric or electropneumatic control unit is particularly
advantageous, and the space required for a continuously operating
conveying appliance in a highly miniaturized test installation for
screening work is therefore very small. This pump principle
operates without a mechanical gear unit, and the required
components of the pump head have no dynamic function, with the
exception of the deflection of the diaphragm in the region of the
shut-off and pumping chamber, so that precision manufacture is not
necessary even for a miniaturized version of the pump components.
There are no mechanical fault influences because of the absence of
mechanical parts and the manufacturing costs for this reproducibly
operating diaphragm pump head are minimized considerably. The pump
requires only a supply of power and compressed air in order to be
capable of operating; these supplies are present in any
laboratory.
[0058] It is particularly advantageous to use the diaphragm pump
for the metering of very small liquid substance quantities, of
which the volume per pumping stroke is substantially below the
specific drop size. By the pneumatic conveying energy being applied
rapidly to the control side of the positive-displacement diaphragm
of the pumping chamber, the sucked-in product volume in the pumping
chamber is thrown out of the product space of the chamber and the
outlet duct and there are no drops formed at the discharge point of
the pump. As a result, a metering of small liquid quantities into a
reaction mixture is not delayed in time and synthesizing is started
in synchronism with the metering.
[0059] The metering of small substance quantities counter to
pressure can be carried out very effectively, since the diaphragms
of the shut-off chambers and pumping chamber are elastic and close
the feeding and discharging product ducts in a gas-tight manner in
the SHUT position of the chambers, so that no substance is forced
back onto the inlet side of the pump via the outlet side of the
pump head by way of the gas phase of a connected pressure vessel
and suction under normal pressure is not interrupted.
[0060] A further advantage, as compared with the prior art, can be
seen in that, by virtue of the small clearance volume and the
leak-tight shut-off and pumping chamber, a sensitive product to be
metered is supplied to the intended location without a long dwell
time and remixing.
[0061] Particularly as compared with microstructure technology,
there are advantages owing to the large duct dimensions in relation
to the metering volume, and the pump is only slightly sensitive to
contamination. A fault which is caused by product contamination and
which is manifested by an increasing metering error or may lead to
the failure of the metering of the pump is greatly reduced on
account of the large product ducts. Product contamination can be
flushed out, during metering, due to the relatively large product
ducts.
[0062] The extremely low hold-up of the pump head and the small
clearance volume ensure a good suction behavior and rapid
reproducible metering, particularly in applications relating to new
pharmaceutical substances which are available only in small
quantities in the early development stage.
[0063] The setting of small metering flows is particularly simple,
because, with the positive-displacement volume being constant, the
metering quantity is set by means of an intermediate timer in the
control. Volume flows can consequently be varied in a very simple
way without cross-checking.
[0064] The lamella construction of the diaphragm pump with
integrated controllable valves, which generates a pulsating
metering flow by virtue of the pumping principle, makes it possible
to equalize the metering flow by a multiplication of the
positive-displacement unit and of the valves, the structural
dimensions of the pump in the test installation not being
appreciably increased.
[0065] Further operational advantages are afforded for the user in
that the wearing parts which are in contact with the product can be
replaced simply and cost-effectively.
[0066] The invention is explained in more detail below, by way of
example, with reference to the figures.
BRIEF DISCUSSION OF THE DRAWINGS
[0067] FIG. 1 shows diagrammatically the set-up of a pneumatic
diaphragm pump constructed in a lamella manner, with an associated
electropneumatic control unit and a programmable electronic control
and also the connecting lines.
[0068] FIG. 2 shows, by way of example, a diaphragm pump, in which
depressions are worked in the middle plate and form the pumping and
shutting-off chambers.
[0069] FIG. 3 shows a pump head with separately inserted elastic
diaphragms for each chamber.
[0070] FIG. 4 shows an application in which a plurality of pumps
are interconnected with a control unit.
[0071] FIGS. 5, 5a show a double diaphragm pump with common
plates.
[0072] FIG. 6 shows a detail of a pumping chamber with a
compensating volume in the control chamber.
[0073] FIGS. 7, 7a show the arrangement and configuration of the
groove or collecting duct in, for example, a pumping chamber.
[0074] FIG. 8 shows a pump with chambers in the outer plates.
[0075] FIGS. 9, 9a show versions of the diaphragm pump with
chambers in the inner plate.
[0076] Referring now to the drawings, the diaphragm pump of the
present invention is comprised of at least three plates, one of
which is a middle plate (203) and two of which are outer plates
(201, 205), the middle plate being disposed between the two outer
plates, said at least three plates forming at least one pumping
chamber (211), at least two shut-off chambers, said at least two
shut-off chambers being a first shut-off chamber (210) and a second
shut-off chamber 212), each of said pumping and shut-off chambers
being in the form of a spherical segment, a spherical zone, a
cylinder or a truncated cone; said middle plate being separated
from each of said outer plates by two diaphragms (202, 204) which
diaphragms also divide said pumping and shut-off chambers into
control spaces (220, 221, 222) and product spaces (230, 231, 232),
the product space (231) of the pumping chamber being connected to
the product space (230) of said first shut-off chamber (210) by a
first connecting duct (208) having an orifice (241) opening into
said pumping chamber, and to the product space (232) of said second
shut-off chamber (212) by a second connecting duct (209) having an
orifice (243) opening into said second shut-off chamber, with an
outlet duct (206) connected to the product space (232) of second
shut-off chamber (212) through an outlet orifice (244), an inlet
duct (207) connected to the product space of first shut-off chamber
(210) through an inlet orifice (240); said pumping chamber (211)
and shut-off chambers (210, 212), together with outlet duct (206)
and inlet duct (207), first connecting duct (208) and second
connecting duct (209) forming a passage duct through said pump,
said control spaces (220, 221, 222) being connected to a control
unit (100, 115) by control lines (119, 120, 121).
EXAMPLES
Example 1
[0077] FIG. 1 illustrates a diaphragm pump 200 in cross section,
with an associated control 100 and a control housing and also a
pneumatic distributor 115. Electronic components and a freely
programmable electric control are installed in the housing. A power
feedline, not illustrated, serves for supplying voltage to the
electronic components. The housing has a display 101, an on/off
switch 102 and a plurality of function keys 103 to 109, by means of
which required parameters for the pumping sequence or for the
pumping operation can be entered, followed visually and stored. The
electronic control 100 allows various operating variants, so that
the pump can be switched to continuous operation by means of the
key 103 and to discontinuous operation by means of the key 104. In
particular, the discontinuous operation of the pump can be set by
means of a preselectable number of pumping strokes and be stored in
the control by means of the key 105. A reduction in the set
parameters is provided by means of the key 106, and the key 107 is
provided for increasing the variable parameters which can then
likewise be stored in the control as newly selected operating
parameters of the diaphragm pump by means of the key 105. In a
continuous operating mode, the time constants can be varied by
means of the keys 106, 107. The key 108 makes it possible to select
between internal and external control of, for example, an external
process management system. The pump 200 begins to operate when the
key 109 is actuated, and when the key 109 is pressed repeatedly,
the operation is stopped again. The electronics with the
programmable control, at the start of metering, transmit via
electric connecting cables 110 digital signals to the
electropneumatic manifold valves 111, 112, 113, 114 which then
switch into their defined open or shut position (Table 1). The
electropneumatic manifold valves 111 to 114 are mounted on a
pneumatic distributor block 115. Manifold valves as used in the
present invention are manufactured for example at SMC Pneumatics
Inc. The distributor block has two supply ducts 116, 117. The
supply duct 116 is connected directly to the compressed-air supply,
and the distributor duct 117 is connected to the vacuum supply by
means of a vacuum line. The vacuum is generated by means of the
vacuum generator 118, an injector, which is installed in the bypass
and which is constantly supplied with compressed air by the valve
114 when the electric control is switched on. In a compact form of
construction, the distributor block 115, together with the
electropneumatic manifold valves and the vacuum generator 118, is
located directly in the housing of the control 100, so that the
compressed-air supply of the supply duct 116 is connected via a
hose coupling 116' and the pump head is connected via the hose
couplings 119', 120', 121'. The freely programmable electronic
components, diodes for the visual function indicator, an electric
power pack and an electric circuit board are not illustrated in
FIG. 1.
[0078] The freely programmable control of the pneumatically
operated diaphragm pump 200 switches the electropneumatic manifold
valves 111 to 114 and conducts the pneumatic pressure, prevailing
in the distributor block 115, in the duct 116 (pressure duct) or
the vacuum in the distributor duct 117 (vacuum duct) through the
control lines (capillaries or hoses) 119, 120, 121 to the pneumatic
control spaces (pneumatic spaces) 220, 221, 222 in the pump
200.
[0079] The valve 111 (V1) is connected by means of the control line
119 to the suction valve (lower shut-off chamber 210) of the
diaphragm pump 200. According to the same layout, the other valve
112 (V2) (upper shut-off chamber 212) and the valve 113 (V3) are
connected to the pumping chamber 211 of the pump 200. The valve 114
(V4) constantly supplies the vacuum generator with compressed air
and is switched immediately as soon as the electronics are supplied
with electrical voltage.
[0080] The diaphragm-pump head 200 consists of the three
part-plates 201, 203, 205 and has inserted elastic diaphragms 202,
204 which are pneumatically deformable in the region of the pumping
chamber 211 and shut-off chambers 210, 212. The diaphragms 202, 204
have the same area as the plates 201, 203, 205, in order to ensure
good sealing-off in relation to the atmosphere. Introduced in the
plates 201, 203, 205 are depressions which form the pumping and
shut-off chambers 210, 211, 212. The shut-off chambers 210, 212 are
worked here, for example, into the plate 201, and the pumping
chamber 211 is worked with a small compensating-volume fraction in
the plate 205 and with the larger volume fraction into the middle
plate 203.
[0081] The shut-off chamber 210 designates, for example, the
controllable suction valve of the pump head. Accordingly, the
pumping chamber 211, the conveying chamber and the shut-off chamber
212 constitute the controllable delivery valve of the pump
head.
[0082] The diaphragms 202, 204 divide the pumping chamber 211 and
shut-off chambers 210 and 212 into control spaces 220, 221, 222 and
into product spaces 230, 231, 232.
[0083] The pumping chamber 211 and shut-off chambers 210 and 212
are in the form of truncated cones. The middle plate 203 has a
suction duct 207 and an outlet duct 206. The two ducts 206, 207 are
in each case extended by a welded-in capillary. The ducts 209, 208
connect the product spaces 230, 231, 232 of the chambers 210, 211,
212 to one another.
[0084] The pumping chamber 211 has a groove 213 as a connecting
element from the lowest geometric point of the depression in the
plate to the outlet orifice or to the connecting duct 209. It also
becomes clear that, between the inlet duct 208 and the start of the
outlet duct 209 with the connecting groove 213, there is still a
sufficient distance to make it possible for the orifices in the
product space of the pumping chamber to be closed sealingly by the
diaphragm 204.
[0085] The diaphragm pump 200 is shown here in the control step 4
(see Table 1). In the region of the shut-off chamber 210
(controllable suction valve), the diaphragm 202 is loaded with
pressure on the control-space side 220, so that the diaphragm 202
shuts off the suction duct 207 at the inlet 240 (FIG. 2) and the
connecting duct 208 at the outlet 241 (FIG. 2). In the region of
the pumping chamber 211 (conveying chamber or positive-displacement
unit), the associated control space 221 is loaded with a vacuum, so
that the diaphragm region lifts off and opens the supplying and
discharging connecting duct 208, 209. The shut-off chamber 212 is
likewise loaded with a vacuum on the control side, so that the
connecting duct 209 and the outlet duct 206 are opened, in order,
in the following control step 5 (see Table 1), to displace the
pump-stroke volume out of the pumping chamber. Necessary screws for
pulling together the plates and at the same time pressing together
the inserted diaphragms are not illustrated in FIG. 1.
[0086] The sequence of programmable control steps and the position
of the valves 111 to 114 are illustrated below in Table 1. The
digital signal "1" means that compressed air is prevailing (result:
the diaphragm is pressed onto the plate 203 and closes), and the
signal "0" means that a vacuum is prevailing (the diaphragm is
raised in the control space and opens). As soon as the electronic
control is supplied with electrical voltage and is switched on by
means of the key 102, the programmed control switches the valves
111 to 114 into a defined starting or basic position. The control
of a complete pump stroke consists here, for example, of five
individual steps. When the pumping operation is interrupted or
terminated, the control jumps into the starting or basic
position.
1TABLE 1 V3 (113) V1 (111) Positive- V2 (112) Suction displacement
Delivery V4 (114) Step valve unit valve Vacuum Basic position 1 1 1
1 1st step 0 1 1 1 2nd step 0 0 1 1 3rd step 1 0 1 1 4th step 1 0 0
1 5th step 1 1 0 1 Back to step 1
[0087] In a control sequence, a variable timer is programmed (not
illustrated in Table 1) after each control step 1-5, so that the
individual control steps proceeding in succession do not influence
one another and are executed completely. The switching times of the
electropneumatic valves are longer and therefore substantially
slower than the time required for transmitting the digital signals.
By means of the intermediate timers, the pumping function is
carried out reproducibly and completely according to the control
cycle 1-5 (Table 1).
Example 2
[0088] FIG. 2 shows a diaphragm pump similar to the pump described
in FIG. 1, but the chambers or depressions 210', 211', 212' are
located in the middle plate 203'. The chambers 210' to 212' here
have the shape of a spherical segment. It can be seen that the
height of the vertex of the depression of the pumping chamber is
greater than the thickness of the diaphragm. In this version, the
center-to-center distance of the supplying and discharging ducts
207, 208 on the suction side of the pump (chamber 210') from each
other is greater than the center-to-center distance of the
supplying and discharging ducts 209, 206 of the delivery valve
(chamber 212') from each other. As a result of the greater
center-to-center distance at the suction valve, the sealing area of
the diaphragm and the leak-tightness of the suction valve is
increased and a backflow of the product during the pumping
operation is prevented.
Example 3
[0089] In FIG. 3, there is a variant of the pump 200 from FIG. 2
with three separately inserted diaphragms 300, 301, 302. The
depressions 210', 211', 212' are all arranged on the inner plate
203' and here form, with the diaphragms 300, 301, 302, the product
spaces 230, 231, 232. With the product ducts open, the diaphragms
300, 301, 302 come to bear on the respective outer plates 201',
205'. In the operating situation, these diaphragms are loaded via
the control-space side with compressed air or a vacuum according to
the control program via a bore, in order to ensure the pumping
function.
[0090] FIG. 4 reproduces, for example, the parallel operation of
three diaphragm pumps 200a, 200b, 200c of the type shown in FIG. 3,
in the non-activated state. These are connected in parallel to the
lines of the pressure distributor 115 in a similar way to FIG. 1.
The pneumatic manifold valves of the pressure distributor 115 are
actuated by means of the electric control, not shown here, and
bring about the actuation of the diaphragms via the control lines
119 to 121 which here are connected, branched off, to the three
pump heads. When the pump heads operate in parallel with one
control unit, care must be taken to ensure that the connecting
lines and also the compressed-air and vacuum supply are
sufficiently dimensioned.
[0091] FIGS. 5 and 5a show a version of the diaphragm pump 200d in
which two pump units or two pump heads have common part-plates. The
part-plates are braced together by means of the screws 500. The
essential contours, and also the pumping chambers and connecting
ducts within the pump head, are illustrated by broken lines in FIG.
5a. The double pump head can be operated by means of one control
unit, so that double the conveying quantity per stroke can be
metered by means of one control stroke (corresponding to step 1-5;
Table 1, FIG. 1). A further use is afforded when pumping chambers
of identical or different size are introduced into the part-plates,
so that two different substances are pumped synchronously by means
of one control unit, or two control units for generating different
substance flows are connected to the common pump head. The inner
set-up of an individual pumping unit corresponds to the pump
according to FIG. 5. FIG. 5a shows clearly that the projection of
the outer contours of the shut-off chambers (501 and 502, 503) of
the chambers overlap with various planes of the plates, in order to
ensure a small clearance volume and thereby a good initial
behaviour of the pump. Furthermore, a particularly compact
pump-head design becomes possible.
[0092] FIG. 6 shows, in cross section, two portions of the plates
203, 205 in the region of the pumping chamber 211 of a diaphragm
pump similar to that of FIG. 1. The volume of the pumping chamber
is distributed in equal proportion to both plates, so that the
inserted diaphragm 301 is braced via a concentric sealing surface
214 and seals off the product space 231 and the control space 221
relative to the outside.
[0093] FIG. 7, 7a shows a top view of the depression in a diaphragm
pump in the form of a spherical-segment geometry of the pumping
chamber 211. The groove 213 provided can be seen, which runs from
the vertex of the pumping chamber as far as the connecting duct 209
and serves as a collecting duct for a complete emptying of the
product space. FIG. 7a shows a further special version of a
branched groove 213' or of the collecting duct 213.
Example 5
[0094] FIG. 8 shows the diaphragm-pump head 200 according to the
invention, with a pumping chamber 211" and two shut-off chambers
210", 212" and with the elastic diaphragm 202" and 204" inserted
between the plates 201", 203", 205". In this design variant, the
diaphragm pump has depressions in the outer plates 201", 205" and
the collecting duct 213" is located in the plate 203".
[0095] The inlet duct 207", the connecting ducts 208", 209" and the
outlet duct 206" and also the collecting duct 213" can be seen.
This embodiment of the pump according to the invention requires a
lower outlay in manufacturing terms.
[0096] FIG. 9 shows a combined arrangement of the connecting ducts
of the pump head. The middle plate is shown in a sectional
illustration and the outer plates 201', 205' can be reduced due to
the arrangement of the passage duct. The inlet duct 207' and
connecting duct 208' between the pumping chamber and the
suction-side shut-off chamber are introduced at right angles to the
outer plate contour, so that the connecting duct 208' is
rectilinear and short. The clearance volume of the collecting duct
208' is thereby minimized. The connecting duct to the delivery-side
shut-off chamber has a greater length and a larger clearance
volume. This version requires a third reduced plate 205' for the
set-up of the pump.
[0097] FIG. 9a illustrates an optimized pump with a small clearance
volume, the middle plate 203' being shown in a sectional
illustration. The geometric areas of the depressions of the
shut-off chambers overlap partially or completely with the
geometric area of the pumping-chamber depression, so that the
connecting ducts from the pumping chamber to the shut-off chambers
are extremely short and an optimized suction behaviour of the pump
becomes possible.
[0098] In FIG. 9a, the connecting duct 209' from the pumping
chamber 211' to the delivery-side shut-off chamber 212' is
positioned at the vertex of the pumping-chamber depression, so that
the collecting duct (cf. FIG. 7) is dispensed with. The clearance
volume of the pump is formed from the volume of the two connecting
ducts 208', 209'. The chamber volume of the suction-side depression
of the shut-off chamber 210' lies partially and the chamber volume
212' completely in the shadow of the pumping-chamber depression
211', so that, with the thickness of the middle plate 203' being
optimized at the same time, the connecting ducts 208', 209' are of
extremely short configuration. The ratio of duct length 208' to
diameter is 3.5.
[0099] The resulting geometric areas of the depressions of the
shut-off chambers on the respective planes of the plates lie
partially or completely in the shadow of the formed geometric area
of the pumping-chamber depression, so that the connecting ducts of
the chambers and the clearance volume of the pump head are thereby
reduced to an extreme extent.
* * * * *