Note: Descriptions are shown in the official language in which they were submitted.
1~4~44~
A Vhi.V HAVIi``G A R11~5-~.,A~`_D, :;O~ABLi VAIVE BOD~
The presen-t invention relates to a valve for connection to
a pipe line, in which -the occurence of underpressure shall
be substantially fully prevented by causing ambient air -to
enter said pipe line through said valve, said valve being
provided with a ring-shaped,movable valve plate made of a
resilient material and on one side of which valve the
pressure prevailing in a circular-cylindrical valve chamber
communicating with the pipe line through the opening in the
centre part of said valve plate acts, and on the other side
of which the atmosphere pressure is arranged to act against
the action of a force which biases the valve plate towards
the valve seating, said other side of said valve plate being
arranged, when abutting a valve seating, to enclose an
annular inlet opening for ambient air. The valve is pri-
marily intended to be opened automatically and to permit air
to enter a drainage system or a water-pipe system, to eliminate
the occurance of unterpressure therein, and to be fully closed
sealed in the absence of any underpressure.
~ecause drainage water flows through non-filled pipes and
entrains air therewith, it is necessary to provide drainage
systems with air inlets in order that said systems function
satisfactorily. Without the provision of an air inlet,
the underpressure created will be so great as to
cause the water-lock or seal to be sucked out,
~ .
~14~4 ~1
enabling the gases given off by the waste to freely enter the
surroundings. In conventional systems, the inlet is arranged
in an aerating line which is terminated above the roof of
the building being serviced. In winter-time, such a system
is encumbered with the disadvantage that water-vapour flowing
out through the air-pipe condenses and forms ice or frost
at the discharge orifice of the pipe, preventing, at times,
air from entering therethrough. This can be prevented by
terminating the air pipe with an automatic valve located
within the building, although it must be ensured that the
valve will function reliably. By terminating the pipe within
the building being serviced, great savings in cost are made,
besides simplifying the installation of the pipe line and the
work required therewith, while, at the same time, eliminating
the risk of leakage through the roof.
The air valve shall normally be closed, and b~ arranged to open
only when the underpressure reaches to above 5 mm vp. The
valve must have a high capacity even at low underpressure,
in order to be suited for drainage systems in which water
locks or seals having a closing depth of 50 mm shall be
protected. The amount of air which is transported when
flushing the drainage system can reach to 30 times the amount
of liquid used to flush said system, and when bearing in
mind that the pressure difference must not exceed 50 mm vp
it will readily be understood that the air valve must not
restrict the through-flow area.
-- 2 --
i~464~
A similar problem is encountered in a water-pipe system, in
which a decreased pressure in the main pipe can cause conta-
minated water, for example water from a toilet or a washing-up
machine, to be sucked back into the main pipe. In order to
prevent such back-suction of contaminated water, so-called
vacuum valves are normally arranged to co-operate with the
toilet or washing-up machine.
One known air valve of the kind described in the introduction
is described in the Swedish Patent Specification No. 325,237.
In this known valve, the movable valve member comprises a
flexible, ring-shaped diaphragm having an outer edge which
is sealingly attached to a cover-plate of the valve and the
inner edge of which normally abuts the upper edge of a
ventilation mouth piece, said upper edge preferably having
the form of a knife-edge, said diaphragm normally being
caused to abut said ventilation mouth piece under the action
of a weight. It is important for the correct functioning of the
valve that the diaphragm is well centered and adjusted, which
is difficult to achieve, inter alia of course the diaphragm
cannot be reached for inspection subsequent to mounting the
valve. A further disadvantage is that the opening area between
the diaphragm and the ventilation mouth piece is very restricted,
despite the fact that the valve has large radial dimensions.
Other known air valves are provided with a spring-loaded valve
plate or flap, which is pivotally journalled and is normally
held pressed against the valve seating. In order to provide a
-- 3 --
~1464~
sealing abutment, the valve plate is provided with an elastic
seal. It is quite possible, that with the passage of time
the valve plate will become distorted or obliquely positioned, so
that the seal is not able to seal against the valve seating
under the action of the necessarily weak spring force.
In order to avoid the aforementioned disadvantages with known
valves, a further valve has been proposed, in which the only
movable part of said valve is a ring-shaped valve plate
arranged in a substantionally circular-cylindrical valve
housing having an annular inlet opening. The clearance or
play in the radial direction of the valve plate must be ex-
tremely small when said plate occupies its sealing position.
If not, the valve plate is unable to cover the inlet opening
if the valve plate should take a position in which any location
of its circumference abuts the inner wall of the valve housing.
Further, the diameter of the said inner wall must decrease
in an upwards direction from the valve seating so that if the
valve plate takes an inclined position it cannot remain in
said inclined position leaning against the inner wall of the
valve housing. This means that when the valve plate takes an
inclined position, the lowest outer edge of said plate can become
clamped against the inwardly inclined inner wall, thereby
causing the valve plate to occupy a permanently open position.
If a relatively high lifting height is to be obtained, the
diameter of the inner wall at the roof of the valve housing
is approximately equal to the outer diameter of the valve plate,
thereby presenting a further risk of the valve plate becoming
jammed in an open position, especially as the ring-shaped
-- 4 --
1~464~1
valve plate can readily obtain the non-roundness required for
the valve plate to easily become jammed and fastening. This
is particularly the case when the air valve is stored lying
on one side over a period of time before being used, in which
case the resilient sealing ring may become permanently deformed,
i.e. non-round or distorted.
The prime object of the present invention is to provide a
valve of the kind described in the introduction which is of
simpler construction than known valves but which, nevertheless,
is more reliable in function than said valves and which will
not cease to function in the intended manner if the movable
valve member or the valve seating should become slightly distorted
or twisted.
This object has been realized by means of the invention, by
providing the valve with a ring-shaped pressure plate of rigid
material, which is arranged on top of the valve plate with a small
clearance to the inner wall of the valve chamber and which is
provided around the outer circumference thereof with an axially
extending guide which prevents oblique setting of the pressure
a plate and which has a smaller measurement in the axial direction
than the inner height of the valve chamber.
As a result of the axially extending guide, the pressure plate
is prevented from fastening against the inner wall of the
valve housing, which may readily occur, since a pressure plate
3L~L464 11
of normal construction not provided with the guide means in
accordance with the invention becomes slightly obliquely posi-
tioned during movement towards the valve seat. If the valve is
stored lying on its side, the resilient valve plate is held
flat, if it is designed to adhere to the under side of the
pressure plate. Even if it is designed to be freely movable
relative to the pressure plate, the valve plate is maintained
substantially flat by the pressure plate, which is constantly
held by the axial guide means in a position with the pressure
plate parallel with the plane of the valve seating.
A particular advantage afforded by a loose valve plate of the
described construction is that it can be made very light. In
the occurence of a period of underpressure of short duration
followed by a period of overpressure, both the pressure plate and
the valve plate are first forced upwards, although when the over-
pressure takes effect, the latter will be returned to the closed
position much quicker than the pressure plate, which has a greater
mass. Even though the light weight valve plate does not fully
seal at the first moment there is obtained, in all events, a
powerful restriction until the pressure plate falls down onto the
valve plate causing the valve plate to seal fully against the
valve seating.
In the known embodiment having solely one ring-shaped valve
plate, an obliquely positioned valve plate will initially
perform a rolling movement when closing the valve, which
greatly delays the closing movement. Such a disa~vantage is
~4644~
not found with the valve according to the invention, since the
pressure plate prevents the valve plate from being obliquely
positioned. In this case, limited possibility of movement of
the valve plate need not cause the through-flow area to be re-
stricted, since said movement can, without difficulty, be practi-
cally of any magnitude. If anything, it is the area between
the concentric rings forming the valve seating which determines
the through-flow area, which, as will readily be understood,
can be given any required size without the dimensions of the
air valve being of unreasonable magnitude. Further, since the
valve plate made of elastic material, is arranged to be loaded by
the guided pressure plate, any minor distortion or twisting of
the valve plate will not affect its function to any great
extent.
The inventionwill now be described in more detail with reference
to the accompanying drawing, which illustrates a preferred
embodiment of an air valve according to the invention, the
left half of the drawing being a vertical view with the valve
housing shown in section, while the right half of the drawing
illustrates the valve and pressure plates in section.
The illustrated air valve comprises a lower pipe connector 1
whose upper end is formed as an inner valve seat 2. An
outer ring 3 concentrical with the pipe connector 1 and
having an outer valve seat 4 is connected with the pipe
connector 1 through radial stays 5. The opening between
the connector 1 and the valve seat 4 forms an annular air inlet 6
for ambient air.
-- 7
1~4~441
The outer ring 3 of the air valve is provided at the top thereof
with a cover 7, which, in certain applications, closes the
thus formed valve chamber 8, but which in the illustrated
embodiment is provided with an opening 9 and an upper pipe
connector 10. The air valve can be coupled to a water-conducting
system (not shown) by means of the pipe connectors 1 and 10.
In the illustrated embodiment the movable valve body of the
air valve comprises two separate, annular parts, namely a light-
weight valve plate 11 of resilient material and a pressure plate10
12 having an axial wall 13 of rigid material around the circum-
ferance thereof. When liquid is to pass through the valve or the
valve is to contain liqu d, the pressure plate 12 is glued along
the surface with which it abuts the valve plate 11, or is joined
to said surface in any other suitable manner, to prevent liquid
from penetrating the upper surface of the valve plate and subject-
ing the plate to excessive deformation pressure. The wall 13 may
be imperforate or, as illustrated, may be provided with openings
14 so as to save material and to reduce weight. Optionally, the
imperforate upper edge of the wall 13 can be omitted, therewith
only axial stays 15 remain of the wall 13.
The valve is normally closed, as shown in the drawing. When
an underpressure occurs in the pipe connectors 1, 10 and there-
with also in the valve housing 8, and said underpressure reaches
to about 5 mm vp, the atmospheric pressure acting on the other
1~464 ~1
side of the valve plate 11 will lift the valve plate and the
pressure plate 12, so that air can flow in through the air
inlet 6, to eliminate the underpressure. The valve plate 11
is held in a horizontal position by the pressure plate 12, the
wall 13 of which prevents the pressure plate 12 from being
obliquely positioned. When the underpressure ceases, or is
followed by an overpressure, the valve plate 11 and the
pressure p]ate 12 return to their respective illustrated positions,
wherewith the valve plate 11 may close, or at least cause a
powerful constriction of the opening 6, before the pressure plate
12 has reached the illustrated position.
Although not shown at least the valve plate or the pressure
plate is provided with at least one central opening for communi-
cation with the chamber 8. As beforementioned, the valve may
be formed as a through-flow valve for gas, or preferably liquid,
although it may also be formed as a valve having a closed opening
9.
