Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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PREg8~U3 ~T-"t~R FOR D13VICE~ TO ~.;O~.~A;)I~
DEL.IV13RY AND MIXING OF HOT AND COLD WATER
* * *
The present invention concerns a pressure
balancer for mixer valves and/or other devices
to deliver hot and cold water to be mixed.
On the one hand, the application of
pressure balancers is already known in, or
upstream of, valves destined to receive and mix
two liquids of different properties, usually
hot water and cold water, and to control the
flow rate and temperature of the mixed liquid
delivered. The basic task of a pressure
balancer is to compare the pressures of both
fluids, hot water and cold water, from the
supply lines, to adjust the flow rates of the
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two fluids delivered to the valve according to
the pressure changes in the supply lines and to
keep the properties of the mixed fluid
delivered by the valve constant, in spite of
these changes in pressure.
On the other hand, various embodiments of
pressure balancers are known for such an
application, which are more or less complex and
show disadvantages of various nature of both
constructional and functional order, well known
to the technicians operating in this sector.
It is an object of the present invention
to provide a pressure balancer which can easily
and simply be applied to hot and cold water
mixer valves and which, on account of a new
structure and an original operating method,
enables effective and reliable comparison
between the pressures of the two types of water
delivered, to correctly equalize the pressures
of the two types of outflowing water to be
mixed and also to fully close the inlet of one
water when the other is not present, so as to
prevent any dangerous delivery of very hot
water.
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Such an object is achieved by a pressure
balancer as claimed in claim 1. Further details
of the invention will become apparent from the
continuation of the description made with
reference to the accompanying drawings, in
which:
Fig. 1 is a sectional view of the balancer
body showing the piston inside;
Fig. 2 shows a cross sectional view of the
balancer; and
Figs. 3 and 4 respectively show a
perspective view of the balancer body viewed
from the side of the water inlet holes and from
the side of the water outlet passages.
The pressure balancer according to the
invention essentially comprises a body 11, a
floating piston 12, a ~uiding bush 13 and a
piston seal 14.
The body 11 comprises two shell elements,
a lower element 15 and an upper element 16,
coupled with a seal 11' interposed so as to
define a chamber 17 housing the piston 12. Said
body is provided with connections 18 at the
base of a hot and cold water mixer valve -
which is known and not illustrated in the
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figures - and with feet 19 for positioning
thereof in the tap designed to receive it along
with the mixer valve. The body 11 moreover
comprises a top packing 20 for seal at the base
of the mixer valve and a bottom packing 21 for
seal in the tap body.
The chamber 17 defined by the body 11
comprises three coaxial cavities: a central
cavity 22, a first side cavity 23 and a second
side cavity 24, the side cavities being on
opposite sides of the central cavity. The side
cavities 23, 24 communicate with the central
cavity 22 through communicating passages 23',
24' respectively, which are tapered with
respect to the diameter of the central cavity
22 and each of which define a valve seat 23~,
24" respectively.
The guiding bush 13 is located and fixed
in the central cavity 22 with a packing 25
placed in between.
It is a guide for the movements of the
floating piston 12. This piston has an
intermediate cylindrical portion 26 and two
terminal flanges 27, 28 which are connected to
the intermediate portion by means of two
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tapered necks 29, 29'. The intermediate portion
26 of the piston 12 is provided with the seal
14 and is conducted in the guiding bush 13. The
necks 28, 29 of the piston freely extend into
the communicating passages 23', 24' and the
terminal flanges 27, 28 are respectively in the
first side cavity 23 and in the second side
cavity 24 and are designed to interact with the
valve seats 23~, 24" around the above mentioned
passages 23~, 24'.
The intermediate portion 26 of the piston
12 divides the central cavity 22 into two parts
A and B: the first of which (to the left in
Fig. 2) communicating with the first side
cavity 23, the second of which (to the right in
Fig. 2) communicating with the second side
cavity 24.
In the lower shell element, the balancer
body 11 has two water inlet holes 30, 31,
communicating respectively with parts A and s
of the central cavity 22 and, in the upper
shell element, two water outlet holes 32, 33
starting out from the side cavities 23, 24.
The inlet holes 30, 31 are respectively
connected with the separate hot and cold water
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supply pipes according to arrows C and F in
Fig. 2; whereas the outlet holes 32, 33 convey
water from the side cavities 23, 24 to the
mixer valve associated with the pressure
balancer. In the balancer body 11 an opening 34
is also provided to receive the water flowing
out of the mixer valve and to channel it
towards the points of use. The upper packing 20
and lower packing 21 on the body 11 are
configured for hydraulic seal around said holes
and opening. Finally, it should be noticed that
the necks 29, 29' of the piston 12 may be
shaped to form a shutter in order to change the
size of the inlet holes 30, 31 according to the
movements of the piston.
Hot water and cold water therefore arrive
separately, through the inlet holes 30, 31, at
parts A and B of the central cavity 22, from
opposite sides of the intermediate portion 26
of the piston 12. This piston moves
automatically to balance and equalize the
pressures of the two types of water directed to
the mixer valve through the outlet holes 32,
33.
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The piston is operated by the difference
in pressure of the water in the cavities at the
opposite sides of the intermediate portion 26
of the piston. With one pressure predominating
over the other, the piston moves and throttles
the flow of water with a greater pressure, thus
partially closing the passage of this water
from the central cavity to the side cavity and
the inlet hole of the same water, if and when
the necks of the piston are shaped to perform
this shutter function.
If one of the waters is not present, the
piston moves and rests its terminal flange on
the side of the water still flowing to the
corresponding valve seat to completely stop
this water flowing in. Since the diameter of
the seal 14 on the intermediate portion 26 of
the piston in the guiding bush 13 is slightly
higher than the diameter of the valve seats
23 n, 24" at the level of the passages between
the central cavity and the side cavities and,
therefore, it is greater than the diameter of
the seal of the closing terminal flange on the
valve seat, the closure is maintained by the
pressure of the present and intercepted water.
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The difference in the diameters of the
intermediate portion of the piston and of the
valve seats is in any case small so that a
small pressure of the water which was missing
is enough to reopen the passage that was
previously closed.
