Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Description
High-power double burner for gas cookers, with multiple concentric
flame crowns.
The present patent application for industrial invention refers to a
double burner for gas cookers, with multiple concentric flame crowns,
characterised by high power and compact height.
The term "double burner" indicates a burner comprising two different
gas inlet conduits, provided with corresponding taps, which separately supply
two or more concentric flame crowns, which can be selectively turned on or
off, being autonomously supplied by two channels derived from the said
separate pair of inlet conduits.
Although provided with multiple concentric flame crowns, traditional
1o burners are characterised in that they only have one gas inlet conduit,
with
corresponding tap, which supplies all channels used to bring the air-gas
mixture to the burner head.
This means that in traditional burners concentric flame crowns are always on
or off simultaneously, while in the case of a double burner the user can
decide to turn on all or some of the flames crowns.
In view of the above, the purpose of the present invention is to provide a
double burner for gas cookers, with multiple concentric flame crowns, of
known type, which is characterised by unprecedented power.
It must be reminded that models of double burners with multiple concentric
flame crowns of known type are characterised in that they use a Venturi-
effect mixing chamber (technically known as "Venturi") with vertical axis for
the central burner, while the mixing chamber of the external burner with
annular shape is obtained with two Venturi with vertical axis or with one
Venturi with horizontal axis.
Since the central burner has limited power due to its position, the external
burner has the highest power, which is entrusted to the Venturi chambers of
the external burner.
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As it is known, the power supported by the Venturi chamber depends on the
diameter of its contracted section, or groove, which in turns affects the
length
of the Venturi diverging section, meaning that the groove section and the
length of the Venturi diverging section must be increased to increase power.
In view of the above, in traditional models of double burners with multiple
concentric flame crowns it is not possible to obtain high power on the
external
burner, since the limited height of the burner prevents from extending the
length of the Venturi chambers with vertical axis of the external burner.
For the aforementioned reasons, double burners with multiple concentric
io flame crowns of known type are currently operated at the end of their
power.
This condition corresponds to high combustion values (values close to
maximum limit set by CEN 30.1 European Norm and out of the range set by
Chinese regulations).
The burner of the invention has been devised to overcome this typical
functional limit of traditional burners. The burner of the invention is
provided
with a central burner traditionally associated with a Venturi chamber with
vertical axis and with a totally innovative external burner associated with
more
than two, preferably four, Venturi chambers with inclined axis and radial
direction, each of them having a unitary power according to the burner
2o dimensions.
For example, in a burner with two Venturi chambers, in order to obtain 4 kW,
each single Venturi chamber must be loaded at 2 kW; in the case of a burner
with four Venturi chambers, reducing the load of each Venturi chamber to
1.25 kW, minus 62.5%, a maximum power of 5kW is obtained, with
consequent reduction of combustion values generated when the external
burner delivers the maximum power.
The burner of the present invention traditionally comprises a tub-shaped
body, whose bottom wall is traditionally provided with two different, non-
communicating conduits with horizontal axis for gas inlet, each of them being
3o designed to selectively supply the aforementioned channels.
Both gas inlet conduits reach the centre of the body at a slightly different
height, in such a way that, if necessary, they can communicate by means of
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a hole with vertical axis that ends in the lower conduit from the upper one.
A vertical channel branches upwards from the upper inlet conduit, on which
the first gas nozzle designed to introduce gas in the mixing chamber that
supplies central flame crowns is mounted. According to the present invention,
more than two ascending and diverging channels branch from the lower inlet
conduit, on which corresponding nozzles designed to introduce gas in the
mixing chamber that supplies the external flame crowns are mounted.
A shaped chamber with Venturi effect is housed downstream each gas
nozzle, which favour mixing of gas with primary air extracted in the upper
part
io of the cooktop.
This means that the burner of the present invention is provided with minimum
four mixing Venturi chambers, one central chamber with vertical axis above
the first nozzle and minimum three regularly spaced three chambers with
inclined axis, respectively supplied by different nozzles.
These chambers are situated inside the burner head, that is to say in the
circular "dish" contained in all models of burners, which is characterised in
that it is provided with a concentric series of multiple toothed crowns, on
which the burner caps are placed to close the cavities of the toothed crowns,
it being known that a flame originates from each cavity.
More precisely, the head is formed of a lower dish and an upper dish, shaped
in such a way that they can perfectly match in order to form the mixing
chambers with inclined axis, while the mixing chamber with vertical axis is
entirely situated in the centre of the upper dish, which is the dish with the
concentric series of multiple toothed crowns.
The lower dish is provided with a lower series of radial partitions that
determine self-centring and detachment from the nozzle-holder body.
Detachment is indispensable to guarantee sufficient introduction of primary
air extracted from above the cooktop.
For major clarity the description of the double burner of the invention
continues with reference to the enclosed drawings, which are intended for
purpose of illustration only and not in a limiting sense, which illustrate a
double burner with multiple flame crowns provided with four Venturi
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chambers with inclined axis designed to supply the external flame crowns.
Figure 1 is a cross-section of the burner of the invention with a diametrical
vertical plane passing through the axis of the gas inlet conduit designed to
supply external flame crowns.
Figure 2 is a cross-section of the burner of the invention with a diametrical
vertical plane passing through the axis of the other gas inlet conduit, which
is
positioned at a higher height than the first conduit.
Figure 3 is a plan top view of the body of the burner according to the present
invention.
lo Figure 4 is a plan top view of the head of the burner according to the
present
invention without caps.
With reference to the aforementioned figures, the double burner of the
invention comprises a circular tub-shaped body (1) which houses a raised
central cross-piece (2) with housings for multiple gas nozzles.
The body (1) traditionally houses two different, non-communicating gas inlet
conduits (3 and 4), each of them selectively and respectively supplying the
nozzle associated with the central flame crown and the group of nozzles
associated with the external flame crowns.
Both gas inlet conduits (3 and 4) reach the centre of the body (1) at slightly
2o different heights; more precisely, the upper inlet conduit (3) exactly ends
in
the centre of the body (1), while the lower inlet conduit (4) goes beyond the
centre, as shown in Fig. 1.
A vertical channel (3a) branches upwards from the upper inlet conduit (3), on
which the first gas nozzle (5) designed to introduce gas in the Venturi mixing
chamber that supplies central flame crown (FC) is mounted; while four
ascending and diverging channels (4a) branch from the lower inlet conduit
(4), on which corresponding nozzles (6) designed to introduce gas in the
mixing chambers that supplies the external flame crowns (FE) are mounted.
A Venturi mixing chamber (5a) with vertical axis is situated downstream the
nozzle (5), while four Venturi mixing chambers (6a) with inclined axis,
preferably from 400 to 60 , are situated downstream the four nozzles (6).
Moreover, the burner of the invention comprises a head (T) formed of a lower
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dish (7) and an upper dish (8) shaped in such a way that they perfectly
match.
More precisely, the lower dish (7) has a truncated-conical profile and has a
stepped external border (7a) that supports and centres the upper dish (8) with
5 a stepped perimeter collar (8a).
The upper dish (8) is also supported and centres in the central flange (9) of
the lower dish (7).
The two dishes (7 and 8) respectively have semi-conduits (7b and 8b) that
form the Venturi mixing chambers (6a); downstream the chambers a deflector
io partition (10) shaped as a V, is situated on the lower dish (7), which
favours
bifurcation of the air-gas mixture flow coming from the chambers (6a),
conveying it inside the corridor (11) that supplies the external concentric
flame crowns (FE), as shown in Fig. 4, which clearly shows the three toothed
crowns (12) above the upper dish (8).
The annular corridor (11) is formed of four identical consecutive and
communicating corridor sections, each of them being bordered by a pair of
deflector partitions (10).
The corridor (11) is closed by an annular cap (13), on whose internal and
external border the aforementioned external concentric flame crowns (FE)
2o are formed.
The Venturi mixing chamber (5) is completely housed in the upper dish (8)
and ends in a circular compartment laterally closed by the toothed crown (12)
with lower diameter and superiorly by a circular cap (14), on whose external
border the central concentric flame crown (FC) is formed.
With special reference to figure 1, the lower dish (7) is provided with a
lower
series of radial partitions (15) that determine self-centring and detachment
from the nozzle-holder body (1), thus guaranteeing sufficient introduction of
primary air (A) extracted from above the cooktop (P).
In order to convert the double burner of the invention into a traditional
burner
with three concentric flame crowns, a hole with vertical axis is drilled in
central position on the body (1), starting from the lower gas inlet conduit
(4)
and ending in the coaxial vertical channel (3a) where the nozzle (5) is
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engaged.
In this way, only the lower conduit (4) needs to be connected to the gas
supply network in order to simultaneously supply all nozzles, the central one
(5) and the lateral ones (6), it being evident that in this case the upper gas
inlet conduit (3) needs to be closed to prevent the gas introduced in the
lower
conduit (4) from exiting the burner body and go up the upper conduit (3).
To avoid using another element in addition to the body (1) of the burner, such
as a closing cap for the conduit (3), the length of the conduit (3) needs to
be
suitably reduced.
lo Since the body (1) is obtained with die-casting process, the reduction in
length can be easily and cost-efficiently obtained by simply moving back the
pin used inside the mould as "core" of the upper conduit (3).
