U.S. patent application number 12/405323 was filed with the patent office on 2009-09-24 for non-return valve for an exhaust duct of flue gasses.
This patent application is currently assigned to MIND AG. Invention is credited to Marco Rossetti.
Application Number | 20090235916 12/405323 |
Document ID | / |
Family ID | 39718286 |
Filed Date | 2009-09-24 |
United States Patent
Application |
20090235916 |
Kind Code |
A1 |
Rossetti; Marco |
September 24, 2009 |
NON-RETURN VALVE FOR AN EXHAUST DUCT OF FLUE GASSES
Abstract
The invention regards a non-return valve for a exhaust duct of
flue gases of a boiler, comprising a valve body in which a passage
opening of flue gases is defined, to said valve body a obturator
being associated which, in a determined operating condition, closes
said opening, said obturator comprising a first swing element,
hinged on said valve body at said passage opening of flue gases.
Advantageously, said obturator comprises a second swing element,
hinged on said valve body at said passage opening of flue gases,
said first and second swing elements being hinged at or in
proximity to a middle plane of said opening.
Inventors: |
Rossetti; Marco; (Milano,
IT) |
Correspondence
Address: |
HUSCH BLACKWELL SANDERS LLP
190 CARONDELET PLAZA, SUITE 600
ST. LOUIS
MO
63105-3441
US
|
Assignee: |
MIND AG
Vaduz
LI
|
Family ID: |
39718286 |
Appl. No.: |
12/405323 |
Filed: |
March 17, 2009 |
Current U.S.
Class: |
126/292 ;
126/319; 454/6 |
Current CPC
Class: |
F23J 2213/204 20130101;
F23L 13/02 20130101; F16K 15/038 20130101; F23L 11/005 20130101;
F23J 2900/13004 20130101; F23J 2213/302 20130101 |
Class at
Publication: |
126/292 ; 454/6;
126/319 |
International
Class: |
F23J 13/08 20060101
F23J013/08; F23L 11/00 20060101 F23L011/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 19, 2008 |
EP |
08005139.4 |
Claims
1. A non-return valve for a exhaust duct of flue gases of a boiler,
comprising: a valve body in which a passage opening of flue gases
is defined; a obturator being associated with said valve body
which, in a determined operating condition, closes said passage
opening; said obturator comprising a first swing element, hinged on
said valve body at said passage opening of flue gases, and a second
swing element, hinged on said valve body at said passage opening of
flue gases; said first and second swing elements being hinged at or
in proximity to a middle plane of said opening.
2. A valve according to claim 1, wherein said passage opening of
flue gases comprises two structurally distinct passage zones of
flue gases, each swing element being active on a respective zone of
said passage zones of flue gases.
3. A valve according to claim 2, wherein said two passage zones are
substantially coplanar.
4. A valve according to claim 2, wherein said two passage zones are
of the same shape and size and they are symmetric with respect to
said middle plane.
5. A valve according to claim 4, wherein said two swing elements
are of the same shape and size.
6. A valve according to claim 3, wherein said plane to which said
two passage zones substantially belong is inclined with respect to
a longitudinal axis of said valve body.
7. A valve according to claim 1, wherein said passage opening of
flue gases is substantially defined in a plane which is inclined
with respect to a longitudinal axis of said valve body.
8. A valve according to claim 7, wherein said plane is inclined,
with respect to said axis, of an angle comprised between 30.degree.
and 60.degree..
9. A valve according to claim 8, wherein said plane is inclined of
about 45.degree. with respect to said axis.
10. A valve according to claim 1, wherein said two swing elements
are hinged to said valve body with clearance.
11. A valve according to claim 10, further comprising said two
passage zones being substantially coplanar, wherein said clearance
is in a parallel plane with respect to, or coincident with, the one
of said two zones.
12. A valve according to claim 1, wherein said opening comprises at
least one raised abutment edge for said two swing elements, said
two swing elements being disposed to rest against said raised
abutment when in said determined operating closing condition of
said valve.
13. A valve according to claim 1, wherein said valve body has a
stop disposed to abut said swing elements, when said two swing
elements are in an operating condition of maximum opening of said
valve.
14. A valve according to claim 13, further comprising said two
passage zones being substantially coplanar and further comprising
two hinges, one for each swing element, and wherein said two hinges
are positioned side by side and said stop comprises a single
element arranged astride said two hinges.
15. A valve according to claim 1, wherein said valve body has
substantially tubular shape.
16. A valve according to claim 15, further comprising at least one
circumferential gasket externally associated to said valve body and
intended to provide seal with an internal wall of said duct.
17. A valve according to claim 15, wherein said valve body
externally has a plurality of centering elements, radially
projecting from said valve body.
18. A valve according to claim 1, wherein said valve body and said
two swing elements are made of plastic material.
19. A valve according to claim 1, wherein said valve body comprises
at least one condensate drainage opening.
20. A valve according to claim 19, further comprising said passage
opening being inclined, wherein said at least one condensate
drainage opening is arranged substantially below said passage
opening of flue gases when the valve is mounted in such a manner
that said longitudinal axis is arranged vertically.
21. The valve assembly of claim 19 further comprising at least one
siphon connected to said at least one condensate drainage
opening.
22. The valve assembly of claim 21, wherein said at least one
siphon has a smaller external size than said valve body.
23. The valve assembly of claim 21, wherein said at least one
siphon is at least partially housed in said valve body.
24. The valve assembly of claim 21, wherein said at least one
siphon is made of plastic material.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority to European Patent
Application Serial No. EP08005139.4 filed on Mar. 19, 2008.
BACKGROUND
[0002] The present invention regards a non-return valve for an
exhaust duct of flue gases of a boiler, preferably but not
exclusively a condensing boiler.
[0003] Non-return valves according to the invention are preferably
used in respective exhaust ducts of flue gases of a plurality of
condensing boilers arranged in cascade, the respective exhaust
ducts being connected to a single main exhaust manifold of flue
gases, in turn connected to a chimney.
[0004] Furthermore, the present invention regards a assembly of
non-return valve for a gas exhaust duct of flue gases of a boiler,
comprising the abovementioned valve.
[0005] With the aim of introducing the prior art non-return valves
for boiler, reference is made to the exemplifying case of a heat
generation plant comprising a plurality of boilers arranged in
cascade.
[0006] With this configuration of the plant, being the overall
thermal power of the plant subdivided over the plurality of
boilers, it is possible to operate only the number of boilers
required to generate the thermal power needed from time to time,
obtaining high efficiency at all conditions of thermal power
supplied, implying a substantial reduction of the plant operating
costs.
[0007] The in-a-row boilers are for example arranged side by side
and the respective exhaust ducts of flue gases are vertically
arranged. Such exhaust ducts are connected to a main exhaust
manifold of flue gases, transversely arranged over the boilers.
Alternatively, the in-a-row boilers can be arranged one over the
other at different floors of a building, and they have horizontal
exhaust ducts, which are connected to a common vertical
chimney.
[0008] Precisely due to the fact that, generally, all the boilers
are not operated simultaneously, it is necessary to prevent that
the flue gases exhausted into the main manifold from the operating
boilers can flow back, from the respective exhaust ducts, into the
non-operating boilers, and therefrom into the environment where the
boilers are installed.
[0009] For this reason, each exhaust duct is exactly provided with
a non-return valve, comprising a valve body in which a passage
opening of flue gases is defined, associated to the valve body
being a obturator which, when the respective boiler is not
operating, closes the opening.
[0010] Document DE 19906736 shows such a non-return valve, in which
the obturator comprises a plate, which can move along the
longitudinal axis of the valve for opening and closing the passage
opening of flue gases. The plate is orthogonally arranged with
respect to the abovementioned axis.
[0011] Document EP 1178262 shows a non-return valve of the
abovementioned type, but in which case the obturator comprises a
double plate, constituted of a first circular-shaped central plate
and a second annular-shaped plate, both plates being capable of
displacing along the longitudinal axis of the valve. When
operating, at a determined pressure difference between upstream and
downstream of the valve, the first plate rises from its seat,
providing a partial opening of the valve, while when such pressure
difference reaches a determined higher value, also the second plate
rises from its seat, hence providing the complete opening of the
valve. The first and the second plate are orthogonally arranged
with respect to the abovementioned axis.
[0012] Document EP 1826487 shows a non-return-valve comprising a
valve body in which is a passage opening of flue gases is defined,
a swing element being associated to the valve body, said element,
when the respective boiler is not operating, closing the opening.
The swing element is hinged on the valve body at the passage
opening of flue gases, which is orthogonally arranged with respect
to the longitudinal axis of the valve body.
[0013] No matter how advantageous from various points of view, the
Applicant found that non-return valves structured according to the
prior art schematically described above reveal several
drawbacks.
[0014] First of all, they can operate only if mounted
vertically.
[0015] In addition, they have the drawback of having a considerable
difference between the passage opening area of flue gases of the
valve and the section of the duct in which the valve is mounted,
thus causing non-negligible pressure drops.
[0016] Furthermore, the obturators of the valves according to the
prior art do not completely free the passage zone of flue gases,
interfering with the flow and causing high pressure drops.
Particularly in the plate valves according to DE 19906736 and EP
1178262, the pressure drops are very considerable, since the
largest section of the obturator is exposed to the flow.
[0017] Additionally, the valves according to the prior art are
cumbersome and, in order to limit the pressure drops, they can be
connected solely to exhaust ducts with a relatively large diameter,
for example greater than or equal to 110 mm.
[0018] Furthermore, the Applicant found that the valves according
to the prior art described above, have a relatively high "opening
pressure" (which is the minimum pressure difference between
upstream and downstream of the obturator required to open the
obturator itself), which can cause malfunctions upon the starting
and at the low power operation of the boiler.
[0019] The technical problem at the basis of the present invention
is to provide a non-return valve for a exhaust duct of flue gases
of a boiler capable of overcoming the above-mentioned drawbacks
referring to the prior art in a simple and inexpensive manner. In
particular, the invention aims at providing a non-return valve with
low pressure drops (that is an area of the passage opening of flue
gases closest possible to the section of duct in which the valve is
mounted, and a negligible hindrance of the obturators to the flow),
a minimal cumbersome and which is capable of being mounted directly
onto ducts having small diameter, for example 80 mm.
[0020] Therefore, the present invention regards, in a first aspect
thereof, a non-return valve for a exhaust duct of flue gases of a
boiler, comprising a valve body in which a passage opening of flue
gases is defined, to said valve body a obturator being associated
which, in a determined operating condition, closes said opening,
said obturator comprising a first swing element, hinged on said
valve body at said passage opening of flue gases, characterised in
that said obturator comprises a second swing element, also hinged
on said valve body at said passage opening of flue gases, said
first and second swing elements being hinged at or in proximity to
a middle plane of said opening.
[0021] Advantageously, the abovementioned non-return valve has a
quicker and more reactive operation with respect to that of the
non-return valves made according to the prior art described above.
Basically, this is due to the fact that each swing element to be
displaced for the opening of the valve has a reduced ratio between
the weight and the passage area of flue gases with respect to that
of the single swing element of EP 1826487.
[0022] Furthermore, the subdivision of the obturator into two swing
elements, which are hinged on the valve body at or in proximity to
a middle plane of the opening, allows the total opening of the
passage area of flue gases, given that the two swing elements can
rotate till 90.degree. without interfering with the internal
surface of the exhaust duct. Additionally, the two swing elements,
when completely open, expose their least section possible to the
flow, unusually limiting the pressure drops.
[0023] In particular, the non-return valve according to the
invention has lower pressure drops with respect to the ones of EP
1826487, especially in conditions of partial opening of the two
swing elements. Basically, this is due to the fact that in the
valve of the invention the flow of the flue gases exiting the valve
body is substantially "subdivided" into two flows, one per each
swing element, each swing element imparting to the respective flow
of flue gases a deviation of lower value, and generally a better
flow progress, with respect to the deviation imparted by the single
swing element of EP 1826487. Experimental tests performed by the
Applicant have confirmed what is mentioned above.
[0024] Experimental tests performed by the Applicant have further
confirmed the fact that the use of a pair of hinged swing elements
in the non-return valve of the invention leads to, considering
exhaust ducts of the same diameter, lower pressure drops and
opening pressures also with respect to the valves described in DE
19906736 and EP 1178262.
[0025] Preferably, the passage opening of flue gases comprises two
structurally distinct passage zones of flue gases, each swing
element being active on a respective passage zone of flue
gases.
[0026] In this manner, advantageously, the closing of the passage
opening of flue gases is ensured in a constructively simple manner,
by making sure that the two swing elements rest on the edges of the
respective passage zones of flue gases.
[0027] In order to simplify the construction of the valve according
to the invention, the two passage zones of flue gases are
substantially coplanar. However, other embodiments are provided,
having good operation characteristics, in which the two passage
zones of flue gases are defined on two incident planes, whose angle
of incidence measured downstream of the valve can be smaller or
greater than 180.degree..
[0028] Preferably, the two passage zones of flue gases are of the
same shape and size and they are symmetric with respect to the
abovementioned middle plane. In this manner, the flow of the flue
gases is subdivided in a substantially balanced manner, limiting
the turbulences and the noise. Additionally, rationalisation of the
valve manufacturing steps is obtained.
[0029] Preferably, in the latter case, also the two swing elements
are of the same shape and size. In this manner the manufacturing
costs are very low and a rationalisation of the valve assembly
steps according to the invention and of the maintenance thereof is
obtained.
[0030] Preferably, in the case where the two passage zones of flue
gases are substantially coplanar, the plane to which the two zones
substantially belong is inclined with respect to a longitudinal
axis of the valve body.
[0031] Additionally, also in the case where the passage opening of
flue gases does not define two structurally distinct passage zones
of flue gases, the passage opening itself is preferably defined
substantially in a plane, which is inclined with respect to a
longitudinal axis of the valve body.
[0032] Through the abovementioned inclination of the plane of the
two passage zones of flue gases, or respectively of the passage
opening of flue gases, it is advantageously possible to use the
same non-return valve, both in the case where it is arranged with
the longitudinal axis in vertical (for example in the case of a
plurality of boilers in cascade arranged side by side and with
vertical exhaust duct), and in the case where it is arranged with
the longitudinal axis in horizontal. The latter case occurs when
the boilers are arranged in cascade one over the other, for example
in the flats of the various floors of a civil building, where the
respective exhaust ducts, which pass through the walls of the
respective flats to be connected to a main vertical manifold, are
arranged horizontally.
[0033] In addition, the condensate which is formed downstream of
the valve of the invention, sliding over the inclined plane, does
not stagnate over the swing elements, as it occurs, on the
contrary, with the obturators of the valves made according to the
prior art described above.
[0034] Furthermore, through the abovementioned arrangement of the
two passage zones of flue gases according to a plane substantially
inclined with respect to the longitudinal axis of the valve body,
the surface dimension of the passage zones of the flue gases is
greater with respect to the surface dimension of zones positioned
on an orthogonal plane with respect to the longitudinal axis of the
valve, thus the opening pressure of the swing elements is lower,
substantially in an inversely proportional manner.
[0035] Preferably, the abovementioned plane to which the two
passage zones of flue gases substantially belong, or respectively
the abovementioned plane of the passage opening of flue gases, is
inclined, with respect to the longitudinal axis of the valve body,
of an angle comprised between 30.degree. and 60.degree.. The
Applicant observed that with the abovementioned angles, non-return
valves with a relatively low opening pressure are advantageously
obtained.
[0036] In order to ensure a substantially identical operation of
the valve according to the invention arranged with the longitudinal
axis in vertical and in horizontal, the above-mentioned angle
preferably measures about 45.degree..
[0037] In a preferred embodiment of the valve of the invention, the
two swing elements are hinged to the valve body with clearance.
Preferably, in the case where the passage opening of flue gases
comprises the abovementioned two zones, such clearance is in a
parallel plane with respect to, or a coincident plane with, the one
of the abovementioned two zones.
[0038] In this manner, any accumulation of soot, and dirt in
general, in the hinges between the valve body and the swing
elements is advantageously prevented. As a matter of fact, the
abovementioned clearance allows a relative displacement between
swing elements and valve body at the hinges, in such a manner to
displace the possibly deposited soot.
[0039] Another preferred characteristic of the valve of the
invention, is that the passage opening of flue gases comprises a
raised abutment edge for the two swing elements, where the two
swing elements rest in the operating closing condition of the
valve.
[0040] In this manner, a good seal of the swing elements on the
passage opening of flue gases (that is on the two passage zones of
flue gases) is advantageously ensured, in a simple and inexpensive
manner. Furthermore, in the case where the two passage zones of
flue gases are substantially coplanar and inclined with respect to
the longitudinal axis of the valve body, such raised edge also
serves to prevent the condensate from falling directly back inside
the valve through the passage zones of flue gases. Furthermore, on
the abovementioned raised edges it is possible to perform a
mechanical flattening, in the case where improvement (or
restoration, in a maintenance operation) of the seal of the swing
elements on the passage opening of flue gases is required.
[0041] A further preferred characteristic of the valve of the
invention, is that the valve body comprises stop means for the two
swing elements, where the two swing elements go in abutment in an
operating condition of maximum opening of the valve.
[0042] In this manner, the risk that the swing elements might
remain "stuck" one to the other, leaving the valve open in absence
of the flow of the flue gases, is advantageously prevented.
Furthermore, the swing elements are prevented from hitting against
each other hence leading to noise and/or damage on the same.
[0043] In case the two passage zones of flue gases are coplanar,
the valve of the invention preferably comprises two hinges, one per
each swing element, such two hinges being positioned side by side,
the abovementioned stop means comprising a single element arranged
astride the two hinges.
[0044] In this manner, the manufacturing and the maintenance of the
valve of the invention is advantageously rationalised.
[0045] Still, another preferred characteristic of the valve of the
invention is that the valve body has substantially tubular shape.
Preferably, such valve comprises a circumferential gasket
externally associated to the valve body and intended to provide
seal with an internal wall of the exhaust duct of flue gases.
[0046] In this manner, the valve of the invention is easy to
construct and it is particularly compact (hence being extremely
suitable in the case of boilers arranged in cascade one over the
other in a civil building). It is advantageously mounted directly
inside the exhaust duct of flue gases, and thus does not require
subdividing the exhaust duct of flue gases and connecting it to the
two ends of the non-return valve, as it occurs in the prior art.
The Applicant found that it is particularly advantageous to
dimension the valve of the invention for being able to house it at
the connection between respective male and female ends of two pipes
of the exhaust duct of flue gases, in such a manner that the
circumferential gasket provides a seal against the internal wall of
the abovementioned female end.
[0047] Preferably, in order to facilitate proper centring of the
abovementioned valve inside the exhaust duct of flue gases, the
abovementioned valve body externally has a plurality of elements
radially projecting from the valve body itself.
[0048] In a preferred embodiment of the valve of the invention, the
valve body and the two swing elements are made of plastic
material.
[0049] This is particularly advantageous especially in the case of
the condensing boilers, where also the exhaust duct of flue gases
is generally made of plastic material, which proved to be ideal for
the low operating temperatures, and the consequent conditions of
operation with dampness, of the condensing boilers.
[0050] It should be observed that the two swing elements are
advantageously shaped in such a manner to allow their construction
by a punching from sheet made of plastic material, instead of the
more expensive injection moulding.
[0051] As a matter of fact, given that the two swing elements are
hinged with clearance on the valve body (they substantially "float"
on the valve body), a high dimensional accuracy is not required,
hence the accuracy obtainable by punching is enough.
[0052] Alternatively, sheets made of composite material, which are
punched, can be used for the swing elements.
[0053] Another preferred characteristic of the valve of the
invention is the fact that the valve body comprises a condensate
drainage opening.
[0054] Preferably, in the case in which the two passage zones of
flue gases are coplanar and inclined with respect to the
longitudinal axis of the valve body, or in the case in which the
passage opening of flue gases is defined on a inclined plane with
respect to the longitudinal axis of the valve body, such condensate
drainage opening is arranged below with respect to the passage
opening of flue gases when the valve is mounted in such a manner
that the longitudinal axis is arranged in vertical.
[0055] In this manner, advantageously, the condensate slides due to
gravity on the inclined top plane of the valve body, until it falls
into the drainage opening. The abovementioned raised edges of the
passage opening of flue gases, which prevent the condensate from
entering directly inside the valve body through the opening itself,
also help the above.
[0056] In its second aspect, the present invention regards a
assembly of non-return valve for a exhaust duct of flue gases of a
boiler, comprising a non-return valve of the abovementioned type
and provided with a condensate drainage opening, and a siphon
connected to the drainage opening itself. In particular, it should
be observed that the siphon is used when the valve is mounted in
such a manner that its longitudinal axis is arranged substantially
in vertical. In the case in which the valve is mounted in such a
manner that its longitudinal axis is arranged substantially in
horizontal (except for a minimum inclination of about 3.degree.,
provided for preventing the condensate stagnation), the valve is
not connected to the abovementioned siphon (and the abovementioned
drainage opening is closed with a plug), and or a drain of the
condensate is provided on the tract of the exhaust duct of flue
gases arranged just downstream of the valve.
[0057] Preferably, such siphon has smaller external size with
respect to the one of the valve body.
[0058] In this manner, the siphon can be advantageously housed
inside the exhaust duct of flue gases, thus the valve assembly is
very compact.
[0059] In order to enhance the compactness, in direction of the
longitudinal axis, of the valve assembly of the invention, the
siphon is at least partially housed in the valve body.
[0060] Furthermore, the siphon is preferably made of plastic
material. This is advantageous especially in the case of the
condensing boilers, where also the exhaust duct of flue gases is
generally made of plastic material.
[0061] Further characteristics and advantages of the present
invention shall be clearer from the following detailed description
of one preferred embodiment thereof, made with reference to the
attached drawings and given for indicative and non-limiting
purposes. In such drawings:
[0062] FIG. 1 schematically represents a perspective view of a
non-return valve, for a exhaust duct of flue gases of a boiler,
according to the present invention, in a operating condition of
closed passage opening of flue gases;
[0063] FIG. 2 schematically represents a perspective view of the
valve of FIG. 1, in a operating condition of open passage opening
of flue gases;
[0064] FIG. 3 schematically represents an exploded perspective view
of the valve of FIG. 2;
[0065] FIG. 4 schematically represents a view of a median and
longitudinal section of the valve of FIG. 1;
[0066] FIG. 5 schematically represents an elevated side view of the
valve of FIG. 2, mounted in a vertical exhaust duct of flue gases,
represented by a dashed line;
[0067] FIG. 6 schematically represents an elevated side view of the
valve of FIG. 2, without the siphon and mounted on a substantially
horizontal exhaust duct of flue gases, represented by a dashed
line;
[0068] FIG. 7 schematically represents an elevated side view of the
valve of FIG. 1, without the siphon;
[0069] FIG. 8 schematically represents a cross sectional view of
the valve of FIG. 7, taken according to the plane having trace
VIII-VIII of FIG. 7;
[0070] FIG. 9 schematically represents an elevated side view of the
valve of FIG. 2, without the siphon;
[0071] FIG. 10 schematically represents a cross sectional view of
the valve of FIG. 9, taken according to the plane having trace X-X
of FIG. 10.
[0072] Referring to the figures, it is shown a non-return valve,
according to the present invention and globally indicated with 10,
for an exhaust duct 11 of flue gases of a boiler (not
represented).
[0073] The valve 10 comprises a valve body 12 in which a passage
opening 14 of flue gases is defined.
[0074] To the valve body 12 a obturator 16 is associated which
closes said opening 14, in a determined operating condition of
valve closing.
[0075] According to the present invention, the obturator 16
comprises a first and a second swing element (18, 20), hinged on
the valve body 12 in proximity to (or at) a middle plane of the
passage opening 14 of flue gases.
[0076] In particular, the valve body 12 has substantially tubular
shape and it is adapted to be placed in the exhaust duct of flue
gases of the boiler. Furthermore, the valve body 12 externally has
a circumferential seat 22a for the housing of a circumferential
gasket 22, intended to provide a seal against an internal wall of
the exhaust duct 11 of flue gases.
[0077] The valve body 12 externally has also a plurality of
radially projecting elements 12a, for example four, preferably
arranged equally spaced from each other in a circumference, for a
proper centring inside the exhaust duct 11. Furthermore, the valve
body 12 comprises a longitudinal external groove 12b, for the
housing of a corresponding internal relief of the duct 11, in order
to ensure a proper orientation of the valve 10 with respect to the
duct 11. Alternatively, the relief can be provided on the valve and
the groove on the duct.
[0078] The opening 14 comprises two structurally distinct passage
zones (14a, 14b) of flue gases, on which the first and the second
swing element, 18 and 20, respectively, is active.
[0079] Furthermore, the two zones 14a and 14b are substantially
coplanar and they are symmetric with respect to the abovementioned
middle plane of the opening 14. In other embodiments of the
invention, the two passage zones of flue gases are defined on two
incident planes, whose angle of incidence, measured downstream of
the valve, may be smaller or greater than 180.degree..
[0080] The plane to which the two zones 14a and 14b substantially
belong is inclined of about 45.degree. with respect to a
longitudinal axis A of the valve body 12. Also embodiments in which
the angle of the abovementioned inclination is comprised between
30.degree. and 60.degree. are advantageous.
[0081] The two zones 14a and 14b of the example illustrated in the
figures have the same shape and size, in particular they have
substantially semi-elliptical shape, comprising a portion of
rectilinear edge, 24a and 24b, and a portion of curvilinear edge,
26a and 26b, which follows a substantially semi-elliptical profile.
The portions of rectilinear edge 24a and 24b are parallel to each
other.
[0082] Also the two swing elements 18 and 20 are preferably of the
same shape and size, in particular they have substantially
semi-elliptical shape corresponding to the one of the two zones 14a
and 14b, comprising a portion of rectilinear edge, 28a and 28b, and
a portion of curvilinear edge, 30a and 30b, which follows a
substantially semi-elliptical profile.
[0083] The portions of rectilinear edge 28a and 28b are parallel to
each other and they are hinged to said valve body 12. In
particular, the portions of rectilinear edge 28a and 28b are hinged
at the opposite ends (29a, 29b and 29c, 29d respectively)
[0084] In the illustrated example the abovementioned ends 29a, 29b,
29c and 29d comprise respective pins projecting from the
abovementioned portions of rectilinear edge 28a and 28b,
substantially in the same direction of the portions of rectilinear
edge, which are housed in respective seats on the valve body 12. In
particular, the abovementioned respective seats are defined between
respective cavities of the valve body 12 and a covering element 32
which is fixed over the valve body 12, at a central portion 34 of
the valve body 12 substantially positioned between the two zones
14a and 14b, i.e. between the portions of rectilinear edge 24a and
24b.
[0085] Preferably, the hinging of the two swing elements 18 and 20
on the valve body 12 is with clearance, hence a great dimensional
accuracy is not required for the abovementioned pins, which can
also have non-circular section (for example they can have
substantially square section, therefore the swing elements 18 and
20 can be made even through simple punching). In particular, the
abovementioned clearance is in a parallel plane with respect to, or
coincident with, the one of the two zones 14a and 14b. For example,
the abovementioned clearance is in the direction of the portions of
rectilinear edge 28a and 28b.
[0086] Preferably, in proximity to the hinges between the valve
body 12 and the swing elements 18 and 20, the valve body 12
comprises projecting protection elements 31, which reduce the
possibility of entry of soot and dirt in general in the hinges
themselves.
[0087] Preferably, the zones 14a and 14b comprise a raised abutment
edge, 36a and 36b, for the two swing elements 18 and 20, which is
developed along the entire respective perimeter of the zones 14a
and 14b.
[0088] Additionally, the valve body 12 comprises stop means 38 of
the two swing elements 18 and 20, where the two swing elements 18
and 20 go in abutment in the operating condition of maximum opening
of the valve 10.
[0089] In the illustrated example, the stop means 38 comprise a
single element 40, arranged astride the two zones 14a and 14b, in
particular between the portions of rectilinear edge 24a and 24b, in
a substantially central position. The abovementioned element 40
has, in a plane orthogonal with respect to the directions of the
portions of rectilinear edge 24a and 24b, a T-shaped section.
[0090] In the illustrated example, in order to facilitate the
assembly of the valve 10, the abovementioned element 40 is integral
to the covering element 32 and it is partially inserted into a slot
34a of the central portion 34.
[0091] Furthermore, the valve body 12 comprises a condensate
drainage opening 42. When the valve 10 is mounted in such a manner
that the longitudinal axis A is arranged in vertical (FIG. 5), such
opening 42 is arranged below with respect to the two zones 14a and
14b.
[0092] The opening 42 is connected to a siphon 44, where the
condensate is collected. The siphon 44 also prevents the flue gases
in the tract of exhaust duct of flue gases positioned downstream of
the valve 10 from flowing back, through the opening 42 itself, into
the tract of exhaust duct of flue gases positioned upstream of the
valve 10.
[0093] Preferably, the siphon 44 has a smaller external size with
respect to the one of the valve body 12. Additionally, even more
preferably, an upper part of the siphon 44 is housed in the valve
body 12.
[0094] The present invention also refers to the assembly of
non-return valve, comprising the valve 10 described above and the
siphon 44.
[0095] In the case (FIG. 6) where the valve 10 is mounted in such a
manner that the longitudinal axis A is arranged substantially in
horizontal (for example in the horizontal exhaust ducts of flue
gases of a plurality of boilers, arranged in cascade one over the
other, in a civil building), the opening 42, which is arranged
superiorly with respect to the two zones 14a and 14b, is closed
with a plug, after having disconnected the siphon 44.
[0096] Preferably, the valve body 12, the swing elements 18 and 20,
and the siphon 44 are made of plastic material. In another
embodiment, the swing elements 18 and 20 can be made of
aluminium.
[0097] Of course, a man skilled in the art can bring numerous
modifications and variants to the non-return valve and the assembly
of non-return valve described above, in order to satisfy specific
and contingent requirements, all of which are however covered by
the scope of protection of the present invention as defined by the
following claims.
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