U.S. patent application number 13/579677 was filed with the patent office on 2012-12-13 for dosing pump.
This patent application is currently assigned to GRUNDFOS MANAGEMENT A/S. Invention is credited to Sergei Gerz, Jan Knedler, Andreas Kraus.
Application Number | 20120312399 13/579677 |
Document ID | / |
Family ID | 42173598 |
Filed Date | 2012-12-13 |
United States Patent
Application |
20120312399 |
Kind Code |
A1 |
Gerz; Sergei ; et
al. |
December 13, 2012 |
DOSING PUMP
Abstract
A dosing pump includes a dosing chamber (14), a suction channel
(32) communicating with the dosing chamber (14) and a pressure
channel (20) communicating with the dosing chamber (14). Features
for popping gas bubbles are arranged in the suction channel
Inventors: |
Gerz; Sergei; (Pfinztal,
DE) ; Knedler; Jan; (Rastatt, DE) ; Kraus;
Andreas; (Karlsruhe, DE) |
Assignee: |
GRUNDFOS MANAGEMENT A/S
Bjerringbro
DK
|
Family ID: |
42173598 |
Appl. No.: |
13/579677 |
Filed: |
February 16, 2011 |
PCT Filed: |
February 16, 2011 |
PCT NO: |
PCT/EP2011/000724 |
371 Date: |
August 17, 2012 |
Current U.S.
Class: |
137/565.01 ;
417/211.5 |
Current CPC
Class: |
F04B 43/067 20130101;
Y10T 137/85978 20150401; F04B 53/06 20130101 |
Class at
Publication: |
137/565.01 ;
417/211.5 |
International
Class: |
E03C 1/00 20060101
E03C001/00; F04B 49/00 20060101 F04B049/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 18, 2010 |
EP |
10 001 641.9 |
Claims
1. A metering pump comprising: a dosing chamber; an intake channel
connected with the dosing chamber; a pressure chamber connected
with the dosing; and a means for breaking up gas bubbles, said
means breaking up gas bubbles being arranged in the intake
channel.
2. The metering pump according to claim 1, wherein the means for
breaking up gas bubbles comprises a sudden cross sectional
expansion in the intake channel.
3. The metering pump according to claim 2, wherein the cross
section of the intake channel expands from a first, smaller cross
section to a second, larger cross section, wherein the surface of
the first cross section corresponds to 0.3 to 0.8 times the surface
of the second cross section.
4. The metering pump according to claim 2, further comprising a
valve in the intake channel, wherein the cross section of the
intake channel expands from a first, smaller cross section to a
second, larger cross section, wherein the smaller cross section is
defined by an outlet of the valve in the intake channel.
5. The metering pump according to claim 4, wherein the valve has a
valve body held in a cage, and the smaller cross section is defined
by a free spaces lying between ribs of the cage and the valve
body.
6. The metering pump according to claim 1, wherein the pressure
channel, in a first section adjoining the dosing chamber, extends
upwardly away from the dosing chamber, inclined relative to a
vertical direction.
7. The metering pump according to claim 6, further comprising a
valve, wherein a second section, that extends in the vertical
direction and incorporates the valve adjoins the first section of
the pressure channel downstream.
8. The metering pump according to claim 1, wherein the intake
channel in a first section adjoining the dosing chamber extends
downwardly away from the dosing chamber, inclined relative to a
vertical direction.
9. The metering pump according to claim 8, further comprising a
valve, wherein a second section that extends in the vertical
direction and incorporates the valve adjoins the first section of
the intake channel upstream.
10. The metering pump according to claim 6, further comprising a
positive-displacement body, wherein the first section of the
pressure channel is inclined in a direction relative to the
vertical direction that faces away from a positive-displacement
body of the metering pump.
11. The metering pump according to claim 1, wherein the pressure
channel and/or the intake channel are connected with the dosing
chamber in the area of its outer periphery.
12. The metering pump according to claim 1, wherein a first section
of the pressure channel and/or a first section of the intake
channel have a diameter greater than 4 mm.
13. The metering pump according to claim 1, further comprising a
valve in the pressure channel and a valve in the intake channel,
wherein a vertical distance between the valve in the pressure
channel and the valve in the intake channel is equal to or less
than 2.5 times, a maximum diameter of the dosing chamber.
14. The metering pump according to claim 1, further comprising a
positive-displacement body comprising a membrane, a valve in the
pressure channel and a valve in the intake channel, wherein a
vertical distance between the valve (26) in the pressure channel
and the valve in the intake channel is equal to or less than an
outer diameter of the membrane forming the positive-displacement
body.
15. The metering pump according to claim 9, further comprising a
positive-displacement body, wherein the first section of the intake
channel is inclined in a direction relative to the vertical
direction that faces away from a positive-displacement body of the
metering pump.
16. A metering pump comprising: structure defining a dosing
chamber; structure defining an intake channel connected with the
dosing chamber; structure defining a pressure chamber connected
with the dosing; and structure breaking up gas bubbles in the
intake channel.
17. The metering pump according to claim 16, wherein the structure
breaking up gas bubbles in the intake channel comprises a sudden
cross sectional expansion in the intake channel.
18. The metering pump according to claim 17, further comprising a
valve in the intake channel, wherein the cross section of the
intake channel expands from a first, smaller cross section to a
second, larger cross section, wherein the smaller cross section is
defined by an outlet dimension of the valve in the intake
channel.
19. The metering pump according to claim 16, further comprising a
positive-displacement body, wherein a first section of the pressure
channel extends upwardly away from the dosing chamber, inclined
relative to a vertical direction that faces away from a
positive-displacement body of the metering pump.
20. The metering pump according to claim 16, further comprising a
positive-displacement body, wherein a first section of the intake
channel is inclined in a direction relative to the vertical
direction that faces away from a positive-displacement body of the
metering pump.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a United States National Phase
application of International Application PCT/EP2011/000724 and
claims the benefit of priority under 35 U.S.C. .sctn.119 of
European Patent Application EP 10 001 641.9 filed Feb. 18, 2010,
the entire contents of which are incorporated herein by
reference.
FIELD OF THE INVENTION
[0002] The invention relates to a metering pump with a dosing
chamber, an intake channel connected with the dosing chamber, and a
pressure chamber (20) connected with the dosing chamber.
BACKGROUND OF THE INVENTION
[0003] Metering pumps are usually designed as positive-displacement
pumps, and as a positive-displacement body have a piston or
membrane that is moved by a drive motor. The positive-displacement
body displaces the volume inside the dosing chamber by a
predetermined amount, so that this volume is conveyed out of the
dosing chamber. The dosing chamber normally has two ports, a
pressure channel and an intake channel, wherein the pressure
channel usually extends perpendicularly upward, and the intake
channel proceeds from the dosing chamber, extending perpendicularly
downward.
[0004] Problems during the metering process are caused by degassing
substances, such as hydrogen peroxide. Gas can in this case form in
the dosing chamber not just in the metering process, but also
during intervals when the pump is not metering. However, gas
bubbles in the dosing chamber result in the volume of liquid
prescribed by the dosing chamber not being metered. For this
reason, it is desirable to divert gas bubbles entering through the
intake channel and present in the dosing chamber away from the
dosing chamber as quickly as possible.
SUMMARY OF THE INVENTION
[0005] In view of this difficulty, an object of the invention is to
optimize a metering pump in such a way as to quickly and reliably
divert from the dosing chamber gas bubbles that might be present or
enter through the intake channel
[0006] The metering pump according to the invention has a known
dosing chamber, which is connected with an intake channel, through
which the medium to be conveyed, in particular the liquid to be
convened, enters the dosing chamber. The dosing chamber is further
connected with a pressure channel, through which the medium
conveyed by the metering pump exits the dosing chamber. The
conveying or pumping action is achieved in a conventional manner by
means of a positive-displacement body, which is arranged on or in
the dosing chamber. The positive-displacement body can consist of a
membrane or piston, for example.
[0007] According to the invention, the intake channel incorporates
a means for breaking up gas bubbles, or the intake channel is
designed in such a way that the gas bubbles entering it through the
intake channel can be broken down into smaller gas bubbles. When
large gas bubbles enter through the intake channel, the danger is
that these large gas bubbles will adhere to the walls of the intake
channel, and hence remain in the intake channel or dosing chamber.
The advantage to breaking the gas bubbles up into smaller gas
bubbles is that it reduces the risk of adhesion to the walls of the
intake channel, allowing these smaller gas bubbles to rise up
through the intake channel and further through the dosing chamber
into the pressure channel more quickly. It is preferred that gas
bubbles situated downstream from a valve in the intake channel in
the dosing chamber rise quickly enough to reach the outlet end of
the dosing chamber after 80% of the overall stroke time (period
between the intake stroke and ensuing pressure stroke), i.e., the
pressure channel and in particular an outlet valve lying in the
pressure channel, so that they can then be expelled from the dosing
chamber toward the end of the pressure stroke. The means for
breaking up the gas bubbles can be arranged as additional elements,
for example projections, ribs or the like, in the intake channel,
preferably downstream from a valve or inlet valve in the intake
channel As an alternative, gas bubbles can be broken up or torn
away by making changes to the cross section of the intake channel,
thereby causing larger gas bubbles to split up into smaller gas
bubbles.
[0008] To this end, it is further preferred that the means for
breaking up the gas bubbles in the intake channel are designed like
an expanded cross section, wherein this expansion in cross section
additionally preferably is sudden, i.e., taking the form of a step
or shoulder. The larger, i.e., expanded cross section of the intake
channel in this case preferably abuts the dosing chamber. The cross
section of this expanded intake channel is preferably greater than
the cross section of the intake channels of conventional metering
pumps. This means that the cross section selected for the intake
channel is intentionally larger than would be required for the
normal operation of the metering pump, so as to improve the removal
of gas bubbles. As a result of the cross sectional expansion,
rising gas bubbles are torn away. Larger gas bubbles will initially
adhere to the wall(s) of the intake channel viewed in the direction
of flow, before the expanded cross section. This means that the gas
bubbles initially stick to the walls in this narrower portion of
the intake channel However, the flow during the intake stroke and
buoyant force tear parts of the gas bubbles away at the expanded
cross section, and the latter then quickly rise in the dosing
chamber as smaller gas bubbles, and exit through the latter to the
pressure channel.
[0009] It is especially preferred that the cross section of the
intake channel expand from a first, smaller cross section to a
second, larger cross section, wherein the surface area of the first
cross section is between 0.3 and 0.8 times the surface area of the
second cross section. It is in this case preferable that the first
narrower cross section is selected such that it essentially
correspond to the cross section, in particular the smallest cross
section, of an intake channel of a conventional metering pump. This
means that the expanded section adjoining downstream is expanded
relative to the cross sectional size of the intake channel of a
known metering pump.
[0010] It is further preferred that the smaller cross section is
defined by the outlet of a valve, i.e., the inlet valve in the
intake channel This outlet represents the narrowest point in the
intake channel In this regard, gas bubbles first get caught in this
constriction, and are then torn away at the outlet end of the
constriction, i.e., at the expanded cross section, and thereby
broken up into smaller gas bubbles.
[0011] It is further preferred that the valve exhibit a valve body
held in a cage, in particular a valve ball, and that the smaller
cross section is defined by the free spaces lying between the ribs
or webs of the cage and the valve body. The cage or ball cage
exhibits webs or ribs extending in the direction of flow, between
which the valve body runs. At the downstream end, these webs or
ribs project radially inward, thereby forming an axial stop there
for the valve body. The liquid to be conveyed flows through the
free spaces between the webs and ribs. The shared cross section of
these free spaces defines the smaller cross section in front of the
expanded cross section. Three or four such ribs or webs forming the
cage are preferably provided.
[0012] The pressure channel preferably extends in a first section,
which borders the dosing chamber, upwardly at an inclination
relative to the vertical, away from the dosing chamber. As a result
of the inclined configuration of this pressure channel, i.e.,
outlet channel, which is situated at the vertical upper end of the
dosing chamber, there are essentially no horizontally extending
upper boundary surfaces in the area of the pressure channel on
which gas bubbles might agglomerate. The inclined progression
yields upper boundary surfaces extending at an inclination relative
to the vertical, along which gas bubbles rise. The inclined upward
progression causes the gas bubbles to continue rising upward along
these surfaces, and hence automatically enter the pressure channel
and rise therein. This ensures that gas bubbles in the dosing
chamber that accumulate at the upper end of the dosing chamber due
to buoyancy reliably enter the pressure channel, and are conveyed
through the latter out of the dosing chamber as quickly as
possible.
[0013] It is further preferred that a second section extending in
the vertical direction adjoin the first section of the pressure
channel downstream. As a result, gas bubbles can also rise
unimpeded and cannot agglomerate in this section either. This
produces a pressure channel having no horizontally running sections
or walls on which gas bubbles might accumulate and adhere.
[0014] It is preferred that a valve is situated in the second
section of the pressure channel This valve can be a check valve,
which is usually arranged at the outlet side of the dosing chamber
in such metering pumps. During the intake stroke of the
positive-displacement body in the dosing chamber, this valve
prevents a reflux of the medium to be conveyed through the pressure
channel into the dosing chamber. This valve is situated in the
vertical section of the pressure channel, so that there are
preferably essentially no horizontal surfaces either, on which
larger gas bubbles might agglomerate. In addition, this arrangement
is advantageous, since such valves normally close under the force
of gravity.
[0015] It is further preferred that the intake channel emptying
into the dosing chamber also is configured in a corresponding way,
so that the intake channel in a first section bordering the dosing
chamber extends downward at an inclination to the vertical, away
from the dosing chamber. As a result, this section of the intake
channel incorporates essentially no horizontally running upper
surfaces on which gas bubbles might agglomerate. Rather, the
inclined progression of the gas bubbles in the intake channel
allows them to rise along the inclined upper wall of the intake
channel, and enter the dosing chamber. They can there continue to
rise and then enter the pressure channel, as described above.
[0016] It is further preferred that a second section extending in a
vertical direction adjoins the first section of the intake channel
upstream. As a result, this section also has no horizontal surfaces
on which gas bubbles might agglomerate.
[0017] However, the inclined first sections of the pressure channel
and possibly the intake channel in this case also make it possible,
as in the hitherto known channels, extending horizontally away from
the dosing chamber, to arrange the ports and possibly the valves of
the intake and pressure channels horizontally offset relative to
the middle of the dosing chamber or to the side of the dosing
chamber. This is most often desirable for constructional reasons,
in order to provide enough installation space for the ports and
valves, since a positive-displacement body, such as a membrane,
along with its drive, is usually arranged directly on the dosing
chamber with one side, limiting the space available for
incorporating ports and valves. In addition, these ports and valves
usually have a diameter greater than the width of the dosing
chamber, in particular viewed in the stroke direction of the
positive-displacement body. In this regard, it is necessary that
these components extend laterally over the boundaries of the dosing
chamber.
[0018] It is further preferred that a valve is situated in the
second section of the intake channel, i.e., in the vertically
extending section of the intake channel This valve can be a check
valve of the kind known for conventional metering pumps. This check
valve closes during a pressure stroke, thereby preventing the
medium to be conveyed from flowing back into the intake channel
instead of into the pressure channel Such a valve is usually
designed to close under gravitational force, making it especially
favorable to be accommodated in a vertical channel section.
[0019] With respect to the arrangement of a valve in the pressure
channel and possibly the intake channel, it must be understood that
several valves can also be arranged there in series.
[0020] It is further preferred that the first section of the
pressure channel and/or the first section of the intake channel is
inclined in a direction relative to the vertical that faces away
from the positive-displacement body of the metering pump. As a
result, the ports for the intake and pressure channel that connect
the metering pump with external line systems, and particularly the
inlet and outlet valves or check valves, can be laterally offset
relative to the dosing chamber. These components can in this case
be offset toward a side facing away from the positive-displacement
body and its drive, where there is sufficient space available for
installing these components, in particular for the valves.
[0021] It is further preferred that the pressure channel and/or
intake channel is connected with the dosing chamber in the area of
its outer periphery. The dosing chamber preferably has a circular
cross section around the horizontal axis, preferably the stroke
axis of the positive-displacement body. The intake channel and
pressure channel in this case preferably extend away from the outer
periphery of the dosing chamber at the lowest and highest point of
the dosing chamber, so that no upper horizontal surfaces on which
gas bubbles might accumulate form there. As a result of the
circular outer periphery of the dosing chamber, the surfaces
adjoining the inlet opening of the pressure channel are also
curved, ascending to the highest point, so that gas bubbles that
accumulate there can continue rising all the way up to the inlet
opening of the pressure channel, where they can then continue
rising in the adjoining first inclined section and the possibly
adjoining second vertical section, and exit the dosing chamber.
[0022] The first inclined section of the pressure channel and
possibly the intake channel preferably extend at an angle of
between 20 and 70 degrees, more preferably at an angle of between
10 and 60 degrees, and particularly at an angle of between 10 and
60 degrees, relative to the vertical.
[0023] In order to improve the passage for gas bubbles, the first
section of the pressure channel and/or the first section of the
intake channel preferably have a diameter greater than 4 mm, more
preferably greater than 5 mm, and particularly greater than 6 mm,
e.g., 6.5 mm. A large channel diameter of this kind ensures that
larger gas bubbles can also quickly traverse the channel, and will
not become lodged in the channel
[0024] It is further preferred that the pressure channel has a
larger diameter or cross section upstream from a valve body
situated in the pressure channel than downstream from the valve
body. As a result of this configuration, gas bubbles can be routed
through the valve in the pressure channel as quickly as possible,
thereby keeping the dosing chamber as devoid of gas bubbles as
possible. The line cross section can then be reduced to the usual
size again downstream from the valve.
[0025] It is further preferred that the vertical distance between
the valve in the pressure channel and a valve in the intake
channel, i.e., the conventional check valve, is as small as
possible. This means that the valves are situated as close as
possible to the dosing chamber, in order to minimize the size of
the channels bordering the dosing chambers and the total volume and
path of the medium to be conveyed between the two valves. Reducing
the distance between the valves in the pressure channel and in the
intake channel shortens the rise time for gas bubbles from the
valve in the intake channel to the valve in the pressure channel,
thereby preferably making it possible to achieve a rise time of
less than 80% of the overall stroke time of the intake and pressure
stroke.
[0026] It is preferred that the vertical distance between a valve
in the pressure channel and a valve in the intake channel is equal
to or less than 2.5 times, and preferably equal to or less than two
times, the maximum diameter of the dosing chamber transverse to the
horizontal axis. This configuration yields a similarly small
distance between the valves.
[0027] In another preferred embodiment, the vertical distance
between a valve in the pressure channel and a valve in the intake
channel, i.e., in particular between the check valves bordering the
dosing chamber, is equal to or less than the outer diameter of a
membrane comprising the positive-displacement body. The membrane
usually extends a certain distance beyond the outer diameter of the
dosing chamber, since it is sealed and fixated in this area.
Because the distance between the valves is equal to or less than
the outer diameter of this membrane, this yields an overall very
compact construction of the metering head of the metering pump, and
in particular keeps the volume lying between the valves as low as
possible, accompanied by the positive effects described above.
[0028] The invention will be described below based on the attached
figures by way of example. The various features of novelty which
characterize the invention are pointed out with particularity in
the claims annexed to and forming a part of this disclosure. For a
better understanding of the invention, its operating advantages and
specific objects attained by its uses, reference is made to the
accompanying drawings and descriptive matter in which preferred
embodiments of the invention are illustrated.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] In the drawings:
[0030] FIG. 1 is a sectional view of a metering pump unit according
to the invention; and
[0031] FIG. 2 is an enlarged sectional view of the pump head of the
metering pump unit according to FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0032] Referring to the drawings in particular, the metering pump
unit has a known motor housing 2 with a pump head 4 placed
thereupon. The motor housing 2 incorporates a drive motor 6, which
drives a connecting rod 10, so that it moves the middle area of a
membrane 12 linearly forward and backward.
[0033] The membrane 12 comprises the positive-displacement body on
a dosing chamber 14 in the pump head 4. The dosing chamber 14 forms
a defined volume, which can be decreased and increased by the
motion of the membrane 12, as a result of which the pump conveys a
defined volume via the dosing chamber 14 during each stroke of the
membrane 12.
[0034] The pump head 4 is arranged in such a way that its upper end
accommodates a pressure port 16, and its lower end accommodates an
intake port 18. The medium to be conveyed or the liquid to be
conveyed is sucked via the intake port 18. The conveyed or metered
liquid is released via the pressure port 18. The pressure port 16
and intake port 18 are provided to be joined with connection
lines.
[0035] The pressure port 16 is connected with the dosing chamber 14
via a pressure channel 20. The pressure channel 20 here has a first
section 22, and a second section 24 that adjoins it downstream. The
first section 22 of the pressure channel 20 extends with its
longitudinal axis A inclined relative to the vertical X, upward
from the dosing chamber 14. This first section 22 of the pressure
channel 20 here ends at the upper end of the dosing chamber 14,
which is circular in cross section relative to the horizontal axis
Y. At the same time, the first section of the pressure channel 22
extends in a curved manner in a direction away from the dosing
chamber 14, which faces away from the positive-displacement chamber
in the form of the membrane 12 or the motor housing 2. In the
example shown, the longitudinal axis A of the first section 22 of
the pressure channel 20 extends at an angle of 45 degrees relative
to the vertical X and the horizontal Y. However, it is to be
understood that another angle can be selected, preferably an angle
of between 15 and 70 degrees. The advantage to the inclined
arrangement of the first section of the pressure channel 22 on the
one hand is that the vertical second section 24 of the pressure
channel 20 can be offset laterally, i.e., toward he horizontal axis
Y, from the dosing chamber 14 in the direction facing away from the
membrane 12. This provides enough space to accommodate the pressure
port 16 and the two valves 26 and 28 lying in the pressure channel
in the pump head 4, without having to place them in proximity to
the motor housing 2. At the same time, the advantage to the
inclined progression of the first section 22 of the pressure
channel toward to a horizontal progression lies in the fact that
any existing gas bubbles in the dosing chamber 14 can rise in the
inclined first section of the pressure channel 22. As a result,
there are no larger horizontal surfaces on the upper side of the
dosing chamber on which gas bubbles can accumulate. Because of its
circular configuration, the remaining peripheral wall of the dosing
chamber 14 is shaped in such a way that it allows gas bubbles to
rise unimpeded up toward the inlet or branch of the pressure
channel 20.
[0036] In addition, the cross section of the first section 22 of
the pressure channel 20 is provided with large enough dimensions,
i.e., the cross section in this example has a diameter greater than
5 mm, allowing even larger gas bubbles to pass unobstructed. The
first section 22 is adjoined downstream by a vertical section 24
that accommodates the two check valves 26, 28, which are connected
in series. The perpendicular progression of the second section 24
also allows gas bubbles in the latter to rise unimpeded. In
addition, the valves 26 and 28 can also be closed by gravitational
force.
[0037] The pressure channel 20 branches away from the dosing
chamber 14 at its highest point. The intake channel 32 empties into
the dosing chamber 14 vertically opposite, i.e., at the lower end.
The intake channel 32 has a first section 34 adjoined downstream by
a second section 36. Just as the first section of the pressure
channel 20, the first section 34 of the intake channel 32 extends
with its longitudinal axis B horizontally downward at an
inclination to the vertical X and horizontal Y. In the example
shown here, the angle of the longitudinal axis B relative to the
horizontal Y and vertical X also measures 45 degrees, but a
different angle could also be selected, preferably in the 15 to 70
degree range. The important factor is that the first section 34 of
the intake channel 32 does not extend horizontally, as the first
section 22 of the pressure channel 20 is also not to extend
horizontally according to the invention. As a result of the
inclined progression of the first section 34 of the intake channel
32, gas bubbles in the intake channel 32 can rise upward unimpeded
in this section. They will glide along the upper wall of the
section 34 and enter the dosing chamber 14, where they will then
rise to the first section 22 of the pressure channel 20 and be
conveyed away through the latter to the pressure port 16.
Therefore, the intake channel 32 also essentially has no
horizontally progressing upper boundary surfaces on which gas
bubbles might agglomerate. As a result of the inclined progression
of the first section 34 of the intake channel 32 in a direction
facing away from the membrane 12 and the motor housing 2, the
intake port 18 with the valves 30 and 38 in the intake channel 32
can be formed in a horizontal direction, laterally offset from the
dosing chamber 14 in the pump head 4, so that these components do
not collide with the membrane arrangement.
[0038] A second section 36 extending in the vertical direction X,
in which two valves 30 and 38 are arranged in series, adjoins the
first section 34 of the intake channel 32 upstream. The valves 30
and 38 also represent two known check valves that close under
gravitational force.
[0039] In addition, the intake channel 32 incorporates a means for
breaking up gas bubbles in the entering liquid stream. In this
case, the means for breaking up gas bubbles is realized in the form
of an expanded cross section. The valve 30 is formed by a valve
ball, which is held in a ball cage 31. The ball cage is comprised
of ribs or webs extending parallel to the vertical X, wherein the
free spaces 33 between these webs define the flow paths through the
valve. The free spaces 33 in the periphery of the ball and between
the webs of the ball cage 31 together define a first smaller cross
section, which is smaller than the cross section in the intake
channel 32 adjoining downstream. In other words, the outlet end of
the free spaces 33 has an expanded cross section. The expanded
cross section is designed in such a way that the overall cross
sectional surface of the free spaces 33 preferably lies between 0.3
and 0.8 times the cross sectional surface of the intake channel 32
adjoining downstream. As a result of this configuration, gas
bubbles that enter through the intake port 18 adhere to the walls
in the free spaces 33 and then are torn off as individual, smaller
bubbles at the expanded cross section toward the intake channel 32
adjoining downstream, so that larger gas bubbles are here broken up
into smaller gas bubbles, and the smaller gas bubbles can then
quickly rise through the intake channel 32, dosing chamber 14 and
pressure chamber 20.
[0040] In addition, the lateral offset of the vertical sections 24
and 36 of the pressure channel 20 or intake channel 32 makes it
possible to arrange the first valve 26 on the pressure side, and
the first valve 30 on the intake side, in close proximity to each
other in a vertical direction X, in order to minimize the overall
volume and distance between these two valves 26 and 30, in
particular the distance between these valves outside the dosing
chamber 14, i.e., essentially the length of the pressure channel 20
upstream from the valve 26 and the length of the intake channel 32
downstream from the valve 30. Another advantage to the above is
that the volume of the medium to be conveyed or the liquid to be
conveyed is as low as possible given a shutdown of the pump, so
that only a smaller quantity of gas can be released in the event of
a degassing medium, keeping the quantity and size of the gas
bubbles accumulating in this area as small as possible. The
distance a between the outlet side of the valve 30 and the inlet
side of the valve 26 is equal to the outer diameter of the membrane
12 in the example shown. Such an arrangement, in which the distance
a is essentially equal to or less than the outer diameter of the
membrane 12, exhibits this kind of expedient small vertical
distance between the valves 62 and 30. In addition, this distance a
has a magnitude equal to or less than 2.5 times, more preferably
less than two times, the maximum diameter d of the dosing chamber
14.
[0041] While specific embodiments of the invention have been shown
and described in detail to illustrate the application of the
principles of the invention, it will be understood that the
invention may be embodied otherwise without departing from such
principles.
* * * * *