Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
2049082
FLOW-CONTROL VALVE ESPECIALLY FOR GASIFIED LIQUIDS
BACKGROUND OF THE INVENTION
The present invention relates to a flow-control valve
especially for gasified liquids, for example, for dispensing
portions of carbonated water from a storage container for
mixing with beverage concentrates in a post-mix beverage-
vending machine.
Such a control valve serves to maintain constant, flow
quantities per unit of time, in order to achieve high
accuracy of the volume of liquid to be dispensed in
conjunction with a time limit for dispensing. For example,
in beverage-vending machines by means of which refreshment
drinks are blended from carbonated water and beverage
concentrates, and then presented for consumption, the given
blending ratio of the two components must be maintained as
precisely as possible, or otherwise variations in taste will
occur which affect the quality of the post-mix drink.
A volumetric dosing system is generally employed for the
beverage concentrates to be blended in relatively small
quantities, thereby again attaining high accuracy in the
volumes dispensed.
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In order to obtain the requisite accuracy in dispensed
volume of the carbonated water and thus to attain the desired
blending ratio, the two components determining the volume,
namely, the flow quantity and the inlet flow period, must be
determined as accurately as possible. The period of flow can
be relatively well controlled by means of accurately timed
opening and closing valves, although the closing and opening
processes can present erroneous values for short dispensing
periods.
Control of the flow quantities is considerably more
problematic. Briefly occurring variations in pressure and
temperature must be considered as well as the fact relative
to gasified fluids that the fluid-gas mixture has a tendency
to degas in the event of pressure loss, turbulent flow, or
heating in the area of the flow-control valve.
In beverage-vending machines the carbonated water is
blended in a so-called carbonator from water and C02 gas,
then stored under pressure and cooled preferably to near the
freezing point. Considerable pressure variations arise
during the dispensing of carbonated water. Dispensing is
carried out in regions of less than atmospheric and hence
steady pressure. During long rest periods the flow-control
valve is warmed; through the dispensing of carbonated water
it is cooled to less than O C. High performance standards,
however, are expected from such a control valve. Moreover,
as an object for commercial production, it should also be
inexpensive.
An assembly for mixing liquids using a pressure-
independent flow-control valve is already known from German
Patent ~DE 34 30 953. The flow-control valve includes a
cylindrical chamber containing a moveable piston driven by
the release energy of a spring.
-- 3
The flowing medium streams through a central hole in the
piston to an outlet in the cylinder which is partially covered
by the control edge of the piston. The spring counters the
force of the medium and applied working pressure. A gap is
provided between piston and cylinder with a sealing function.
The gap, therefore, is narrow with tight tolerances.
Accumulations of dirt between piston and cylinder disturb the
control function and lead to erroneous outputs or to breakdown
of the a~sembly. In addition, the relatively complex
construction of the conventional control valve with a number
of other moveable parts involves the risk of breakdown of the
entire assembly if the operational capability of even one
single part is adversely affected.
SU~ARY OF THE INV~;NL10N
In view of these facts it is an object of an aspect of
the present invention to create a compactly constructed flow-
control valve that contains only a small number of individual
moveable parts.
An aspect of the invention is as follows:
In a post-mix beverage dispenser, a flow-control valve
for dispensing portions of carbonated water from a storage
container for mixing with beverage concentrates, said flow-
control valve comprising:
a valve housing, the interior of which broadens from an
inlet opening to a chr 'er of a membrane with an orifice
therein arranged orthogonally to the direction of the
inflowing water, a pin with a conical tip defining a
continuous conical surface aligned with the orifice and
disposed in the chamber on the opposite side of the
membrane to the inlet opening in close proximity to the
orifice such that the water flowing into the chamber
passes through the orifice in the membrane and displaces
the membrane in the direction of the pin to change the
effective size of the orifice.
~ ~4sos ~
- 3a -
By way of added explanation, a flow control valve
embodying the invention is characterized in that the interior
of the valve broadens out from an inlet to a chamber in which
a pierced membrane defining a central orifice is arranged at
righ~ angles to the direction of water flow, a pin being
arranged in the ch~mher on the opposite side of the membrane
to the inlet in the vicinity of the orifice in such a way that
water flowing into the chamber passes through the orifice in
the membrane, pressing it in the direction of the pin.
The invention is characterized by a number of advantages.
The valve contains only one moveable part, namely the
m~mhrane, which in contrast to the conventional
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piston is not freely moveable but stretched across the body
of the valve.
The membrane has practically no wear and thus ensures
long life for the valve. The relatively low mass of the
membrane produces a very short address and start-up time.
The valve can be compactly and - on account of the
simple design - inexpensively constructed. The compact
structure is particularly evident when the valve consists of
only two housing components, where a first housing component
with the inlet in its interior forms the chamber adjoining
the inlet as well as the circular space for the membrane, and
where a second housing component with the outlet in its
interior forms a space open to the outlet as well as the
bearing for the pin and the counter-bearing for the membrane.
A further advantageous construction format is specially
characterized in that the chamber has on the side opposite
the inlet a bearing support, against which the membrane
presses at a given pressure of inflowing water. This
enhances the spring stiffness of the membrane. Plastic
deformation of the membrane, which would limit the capability
of the valve, is prevented.
The pin is advantageously mounted orthogonally to the
membrane and adjustably. The adjustable mounting permits the
compensation of production tolerances.
In a further advantageous construction format according
to the invention, the pin has a stop which limits its
adjustable travel in the direction of the membrane. This
prevents the pin from contacting the membrane, even at
maximum pressure of the inflowing water which could reduce
its capability or destroy the membrane.
A further benefit is that the pin has a conical tip in
the vicinity of the orifice in the membrane, particularly
with an angle of 90 . With this form of pin construction the
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influence of possible aeration of the water by C02 and
temperature dependence is so small that a given tolerance in
the quantity dispensed is maintained.
Particularly beneficial in terms of flow mechanics is a
construction format where the chamber inside the valve has a
circular cross-section in the membrane area and the orifice
is located in the center of the membrane. Thereby the
membrane has a circumferential support at a given distance
from its circular outer edge.
A further advantageous construction format of the valve
is specially characterized in that the chamber extends to the
opposite side of the membrane from the inlet and forms a
space opening to an outlet. This space receives the water
flowing through the hole in the membrane and is so
constructed depending on the diameter of the outlet that the
water creates a given back-pressure and emerges from the
valve as a focussed jet. This is also achieved by having the
outlet emerge into an outlet tube whose diameter is larger
than that of the outlet itself.
A further advantageous construction format is specially
characterized in that the outlet is angled against the flow
direction of the water. The angle in particular is 90-.
Diverting the flow direction of the water delays outlet speed
and hence also reduces the generation of noise.
Further scope of applicability of the present invention
will become apparent from the detailed description given
hereinafter. However, it should be understood that the
detailed description and specific examples, while indicating
preferred embodiments of the invention, are given by way of
illustration only, since various changes and modifications
within the spirit and scope of the invention will become
apparent to those skilled in the art from this detailed
description.
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BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will become more fully understood
from the detailed description given hereinbelow and the
accompanying drawings which are given by way of illustration
only, and thus, are not limitative of the present invention
and wherein:
The sole figure of the drawings is a cross-sectional
view through the flow control valve of the present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
The interior of the valve shown in the drawing broadens
., . ' , ' '.f,''',~ ~
from an inlet opening 1 to a chamber 2~ In the construction
format shown in the drawing, the transitional stage between
inlet opening 1 and chamber 2, which is circular at least in
the area of the membrane 3, and the chamber wall have a
curved profile. Such a shape without sudden volume change
prevents any significant outgassing of gasses contained in
the water.
The membrane 3 is arranged orthogonally to the direction
of flow of the incoming water and includes an advantageous
central orifice 31, whose diameter is preferably smaller than
or equal to the diameter of the inlet opening 1.
on its side opposite the inlet opening the chamber forms
a space 21 in which a pin 4 protrudes. The pin 4 is located
in the extension of the path leading from the inlet opening
1 through the orifice 31 in the membrane 3.
The pin 4 has an advantageously conical tip with an
angle of 90- in the area of the hole in the membrane. It can
be mounted adjustably along an axis orthogonal to the
membrane and is constructed as an adjustable screw.
Adjustment travel in the direction of the membrane is limited
by a stop 41. ~
8 ~
-- 7
By means of the pin the working point of the valve is
adjusted. The working point for a given distance between the
(loaded) membrane and its particularly conical surface in the
area of the membrane ori~ice is essentially determined by the
diameter of the membrane orifice, the stiffness of the
membrane and the position of the membrane inside the chamber.
Adjusting the pin 4 permits only a narrowly limited change to
the control range of the valve; the adjustment serves
primarily to compensate any existing production tolerances.
The membrane 3 is supported circumferentially at a given
distance from its circular outer edge. The circular or ring-
shaped bearing for the membrane is formed in part by the
first housing component 81 shown on the right hand side of
the drawing and in part by the second housing component 82
shown on the left hand side in
the drawing. The membrane 3 is stretched by both housing
components, whereby the housing components form a free space
83 for the circular outer edge of the membrane in the area of
the membrane bearing. Should inflowing water press against
the membrane, the latter moves towards the pin 4 in the area
of its central hole and upwards in the area of the free space
83 (in the drawing) formed by the housing components.
Both housing components 81, 82 are so shaped in the area
of the membrane bearing that they support the movement of the
membrane under the effect of pressure changes occurring at
the membrane. For example, the first housing component 81
has the rounded shape shown in the drawing in the area of the
membrane bearing at the foot of its outer wall 81a, which
simultaneously forms one wall of the free space 83. A
correspondingly rounded shape is shown by the second housing
component 82 at the side of a horizontal membrane bearing 82a
facing the center of the valve.
Should the inflowing water exceed a given pressure, the
membrane 3 is supported on a bearing 5 located on the
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opposite side of the membrane 3 to the inlet opening 1. This
increases the spring stiffness of the membrane 3; its plastic
deformation that could limit or destroy its capability is
avoided. At the same time the control range of the valve is
extended. '~ '
The chamber~2iin the flow-control valve extends to the
opposite side of the membrane 3 from the inlet opening and
forms a space 21 that opens to an outlet opening 6. The pin
4 is located in the center of this space 21.
Immediately next to the membrane 3 the space 21 forms a
horizontal disk-shaped area 85~) which is bounded in the
upwards direction by the membrane in its, rest position and in
the downwards direction by the bearing~ ~ The height of the
area ~ corresponds to the membrane bowing at a given target
pressure. The space formed by the area 8~ permits small dirt
particles to be rinsed out of the water through the pump-like
motion of the membrane 3 in response to pressure changes.
The space 21 receives the water flowing out through the
orifice 31 in the membrane 3 and the tip of the pin 4 and
guides it to the outlet opening. The space is so
proportioned that the water develops a given back-pressure
and thus gas bubbles formed by gas separating from the water
are carried out with it.
The outlet opening 6 is located in a peripheral area of
the space 21 and is thus angled against the vertical
direction of water flow. In particular the outlet opening is
angled at 90- with respect to the direction of water flow.
The outlet opening communicates into an outlet tube 7
that preferably has a diameter larger than that of the outlet
opening 6. The narrow passage formed by the outlet opening
6 as well as the diversion of the water flow delays the
emergence of the water and reduces the outflow speed. This
also reduces the noise developed by the outflowing water.
2~4~8~
g
The mentioned ratio of the diameters of the outlet
opening 6 and the outlet tube 7 has the effect that the
emerging, decelerated water is focussed and fills the entire
width of the outlet tube 7, thus preventing the issuing jet
from spraying.
The membrane 3 assumes the function of the conventional
piston and spring. In the flow-control valve according to
the invention, control is exercised by a ring-shaped gap
between the membrane orifice 31 and the conical surface of
lo the pin 4. The pressure of the inflowing water inside the
valve moves the membrane 3 in the direction of the conical
surface of the pin 4, thereby adjusting the ring-shaped gap
independently from the water pressure and the elastic
strength of the membrane 3. This forms the opening surface
for the water.
The control process also depends on the diameter of the
membrane orifice 31.
Control first begins when the opening surface through
the ring-shaped gap is less than the surface of the membrane
orifice.
The compact construction of the flow-control valve is
also evident in that it consists simply of two housing
components, that is a first housing component 81 with the
inlet opening 1 and a second housing component 82 with the
outlet opening 6. The firs,t housing component 81 forms in
its interior the chamber 2 ad~oining the inlet opening 1 as
well as the circular bearing for the membrane 3. The second
housing component 82 forms in its interior the space 21 open
to the outlet opening 6 as well as the bearing for the pin 4
and the counter-bearing for the membrane 3. The outlet tube
7 is advantageously integrated in the second housing
component 82 as shown in the drawing.
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Both housing components 81, 82 are sealed against each
other in the area of the ring-shaped bearing for the firmly
stretched membrane. The two housing components are further
sealed by a seal ring 84.
The flow-control valve can be set for pressure ranges,
for example, of 4 +/-1 bar and 5 +/-1 bar. Other pressure
ranges or flow quantities can be achieved through appropriate
changes to the membrane hole.
The invention being thus described, it will be obvious
that the same may be varied in many ways. Such variations
are not to be regarded as a departure from the spirit and
scope of the invention, and all such modifications as would
be obvious to one skilled in the art are intended to be
included within the scope of the following claims.
