[0001] The present invention relates to a burner for professional or domestic gas cookers,
particularly of the type of vertical-flame burners adapted for cooking with woks and
the like.
[0002] Nowadays, in the sector of makers of burners for professional or domestic gas cookers,
vertical-flame burners are known which are particularly adapted to perform types of
cooking that require the use of pans with bottoms that are rounded, not flat, such
as pans known by the Chinese name of woks.
[0003] In order to be used correctly, these pans need their lower central point, where the
food to be cooked collects, to be directly lapped by the flame.
[0004] Radial flame burners are not suitable for this purpose, because they involve the
formation of one or more crowns of rays of flame extending from substantially horizontal
orifices and the absence of nozzles adapted to form a central flame, in accordance
with the widespread need to use flat-bottomed pans in European and Western cuisine
in general.
[0005] Moreover, cooking methods using woks generally require thermal flows that are much
higher than those generated by the radial flame burners which are adapted to the needs
of European cooking.
[0006] So, for the formation of centrally-concentrated flames, nowadays burners are known
that are fitted with burner caps that have a series of central orifices, which extend
substantially vertically and are adapted to form a plurality of rays of flame that
are gathered centrally in the burner.
[0007] These types of burner however have a high combustion inefficiency, which is due to
the difficulty of the combustible gas mixing with an adequate quantity of secondary
oxidizing air.
[0008] Indeed, these burners have a chamber, below the burner cap, which is fed by a Venturi-type
tube into which the gas is injected and into which oxidizing air, known as primary
air, is sucked by the Venturi effect.
[0009] In order to obtain an efficient mixing of the primary air with the gas, and an exit
speed of their mixture from the orifices which is sufficiently low to prevent the
phenomenon of flame detachment, nowadays these burners have long Venturi-type expansion
tubes and large chambers, to the detriment of containing their encumbrance.
[0010] Moreover, for correct combustion, the gas mixed with the primary air needs to be
further mixed with oxidizing air, known as secondary air.
[0011] This mixing occurs at the ejection from the orifices of the burner cap, but, owing
to the density of the rays of flame and the high outflow of gas necessary to generate
the thermal power required, the mixing with secondary air is inefficient and leads
to a scant efficiency of combustion, and it also induces the noisy phenomenon of flame
detachment, i.e. of the formation of the flame in a detached position above the orifice
supplying the mixture of gas and primary air.
[0012] Thus, in order to overcome these limitations, nowadays burners are known which have
an annular body in which a tubular chamber is defined that has a series of slits facing
towards the central axis of the body.
[0013] In use, the gas, mixed with the primary air, is injected by means of a Venturi-type
tube tangentially into the tubular chamber, from which it exits through the suitably
positioned slits inclined towards the center of the burner body where, mixing vortically
with the secondary air sucked in through the central opening delimited by the annular
body of the burner, it burns effectively, forming a flame that rises centrally from
the burner.
[0014] This type of burner however has the drawback of producing a flame that is highly
concentrated in its center, and thus it is adapted to perform types of cooking that
involve the use of pans of greater thickness, which are capable of diffusing the heat
with a good level of uniformity throughout the portion of the bottom thereof which
is in contact with the dish to be cooked.
[0015] On the other hand, for wok pans which are made with a relatively thin layer, the
strong central concentration of the flame in the central region alone of the burner
induces a strong temperature gradient, which rapidly decreases towards the periphery
of the pan, to the detriment of an efficient cooking session.
[0016] Nowadays, in the wake of the spread of the use of woks in Western cuisine as well,
the need is increasingly felt to provide central flame burners that make it possible
to effectively heat these pans, by providing adequate thermal flows and concentrated
flames that are adapted to effectively heat all of the central portion thereof, while
enabling an efficient burning of the combustible gas.
[0017] The aim of the present invention is to provide a burner that makes it possible to
meet this need, by enabling the formation of a central flame which is obtained by
means of an efficient burning of the combustible gas.
[0018] Within this aim, an object of the invention is to provide a burner that makes it
possible to prevent the phenomenon of flame detachment.
[0019] Another object of the invention is to provide a burner that makes it possible to
present an ample heating region in order to enable the effective heating of a greater
portion of the pan compared to that which can be effectively heated by the burners
known today.
[0020] Another object of the invention is to provide a burner that, thanks to the stability
of its flame, makes it possible to modulate the thermal power dispensed commensurately
to the level useful to obtaining the correct cooking of the foodstuffs to be cooked.
[0021] A further object of the invention is to provide a burner that is structurally simple
and easy to use, and which can be produced at relatively low cost.
[0022] This aim, as well as these and other objects which will become better apparent hereinafter,
are achieved by a burner for professional or domestic gas cookers, particularly of
the type of vertical-flame burners adapted for cooking with woks and the like, characterized
in that it comprises
- a burner body which is substantially annular and encloses a tubular chamber that lies
in a substantially helical arrangement around a central axis and is provided with
an access hole,
- a Venturi-type supply tube, which is connected to said body and opens onto said hole
to introduce the combustion gas into said chamber, said body being provided with
- upper outflow ports for said gas, which open onto the face of said body that is the
upper one during use and are adapted to form a flame that is oriented substantially
along said central axis,
- central outflow ports for said gas, which open onto said body substantially toward
said central axis.
[0023] Further characteristics and advantages of the invention will become better apparent
from the description of a preferred, but not exclusive, embodiment of the burner according
to the invention, illustrated by way of non-limiting example in the accompanying drawings
wherein:
Figure 1 is an exploded perspective view of a burner, according to the invention;
Figure 2 is a view of a burner, according to the invention, in a configuration of
use;
Figure 3 is a plan view of a component of a burner, according to the invention;
Figure 4 is a cross-sectional view of a burner, according to the invention, taken
along the line IV-IV in Figure 3;
Figure 5 is an enlarged-scale view of a detail of a burner, according to the invention,
partially cross-sectional along a meridian plane and partially cross-sectional along
the line V-V in Figure 3.
[0024] It should be noted that everything found to be already known during the patenting
process is understood not to be claimed and to be the subject of a disclaimer.
[0025] With reference to the figures, the reference numeral 10 generally indicates a burner
for professional or domestic gas cookers, particularly of the type of vertical-flame
burners adapted for cooking with woks and the like, which has a distinctive characteristic
in that it comprises
- a body 11 of the burner 10 which is substantially annular and encloses a tubular chamber
12 that lies in a substantially helical arrangement around a central axis A and is
provided with an access hole 13,
- a Venturi-type supply tube 14, which is connected to the body 11 and opens onto the
hole 13 so as to introduce the combustion gas into the chamber 12,
the body 11 being provided with
- upper outflow ports 15 for the gas, which open onto the face 16 of the body 11 that
is the upper one during use and are adapted to form a flame that is oriented substantially
along the central axis A,
- central outflow ports 17 for the gas, which open onto the body 11 substantially toward
the central axis A.
[0026] Advantageously, the Venturi-type tube 14 defines, for the gas, an inflow direction
B, in the chamber 12, which is substantially tangential to the central axis A.
[0027] In this way, the gas introduced through the Venturi-type tube 14, and mixed therein
with primary air, is conveyed through the chamber 12 according to a helicoid flow
which in Figure 1 is shown for the purposes of non-limiting example with the dotted
curve indicated by the reference letter C.
[0028] The upper outflow ports 15 comprise orifices 18a and 18b which are arranged substantially
circumferentially to the central axis A and peripherally to the body 11.
[0029] The orifices 18a and 18b comprise first orifices 18a and second orifices 18b provided
at different radial distances from the central axis A, the first orifices 18a, with
respect to the second orifices 18b, being offset circumferentially around the central
axis A.
[0030] Moreover, the upper outflow ports 15 conveniently also comprise an annular opening
19 that is peripheral to the body 11.
[0031] The central outflow ports 17 are preferably slot-shaped and distributed substantially
uniformly on a wall 20 of the body 11 that is substantially frustum-shaped and diverges
upward, during use, and is substantially coaxial to the central axis A, which it faces.
[0032] The central outflow ports 17 furthermore advantageously extend substantially along
planes D which are tangent to a cylindrical surface E which has a selected radius
and is coaxial to the central axis A, as illustrated for the purposes of non-limiting
example in Figure 3.
[0033] In this way the gas, mixed in the Venturi-type tube 14 with the primary air, and
swirling according to the helicoid flow C, exits through the central outflow ports
17 while maintaining a rotational component that creates a vortical motion of the
flame which is shown for the purposes of non-limiting example in Figure 3 with the
arrows indicated with the reference letters F.
[0034] This vortical motion F generates a fluid-dynamic vacuum effect at the central space
21 delimited by the body 11.
[0035] Thus, to the draft of secondary air through the central space 21, owing to the burning,
the draft generated by the vacuum is added, to the advantage of an efficient supply
of secondary air to the curtains of flame in use which are formed by burning the combustible
mixture flowing from the central outflow ports 17.
[0036] More specifically, the body 11 comprises
- a base 22, which comprises a bottom 23 shaped like a helical ramp, and a perimetric
collar 24,
- a cover 25, which comprises an annular portion 26 and the wall 20 and is adapted to
mate complementarily with the base 22.
[0037] The orifices 18a and 18b conveniently open onto the annular portion 26, which has
a peripheral circular flap 27 that is adjacent to the orifices 18a and 18b, for resting
in a contoured seat 28 provided at the edge 29 of the collar 24.
[0038] The flap 27 and the edge 29 conveniently define the annular opening 19, below the
flap 27 slits 30 being also provided for communication between the chamber 12 and
the annular opening 19 to feed the gas thereto so as to form, in use, a curtain of
pilot flame for igniting the gas that flows out of the orifices 18a and 18b.
[0039] In this way, in use the curtain of pilot flame develops in the direction of the central
axis A, i.e. vertically, and ensures the effective burning of the gas mixed with the
primary air that exits through the orifices 18a and 18b, thus enabling a prompt ignition
thereof at the opening of the orifices, so as to prevent the phenomenon of flame detachment.
[0040] In practice it has been found that the invention fully achieves the intended aim
and objects by providing a burner that makes it possible to form a central flame that
is obtained by means of an efficient burning of the combustible gas, thanks to the
combined effect of the draft due to burning and the draft due to the fluid-dynamic
vacuum effect induced by the vortical nature of the curtains of flame formed, in use,
by the central outflow ports.
[0041] A burner according to the invention makes it possible to prevent the phenomenon of
flame detachment, particularly of the vertical flames which burn the gas flowing out
from the orifices, partly thanks to the burn-assist effect generated, at the orifices,
by the presence of the curtain of pilot flame, which in use is lit adjacent thereto.
[0042] What is more, a burner according to the invention makes it possible to present an
ample heating region in order to enable the effective heating of a larger portion
of the pan compared to that which can be effectively heated by the burners known today,
this heating region being obtained from the combination of the curtains of flame emanating
from the central outflow ports, with the rays of flame emanating from the orifices
that are perimetric to the burner body.
[0043] A burner according to the invention is also structurally simple, easy to use, and
can be made at relatively low cost.
[0044] Thus, in particular, a burner according to the invention makes it possible to obtain
a high level of thermal power thanks to the combination of the two types of flame
obtained, namely
- the central flames, which come from the central outflow ports with vortical motion
and aspiration of the air from the central space, and
- the vertical flames, perimetric to the burner, which are powerful and efficient thanks
to the curtain of pilot flame which enables their ignition right from the openings
of the orifices, thus hindering flame detachment.
[0045] The stability of the flames that can be obtained using a burner according to the
invention allows the modulation thereof, for example by modulation means which are
known per se and which are not shown or described here, the burners used today for
cooking with woks being in contrast substantially incapable of allowing the modulation
of the thermal power produced.
[0046] The invention, thus conceived, is susceptible of numerous modifications and variations,
all of which are within the scope of the appended claims. Moreover, all the details
may be substituted by other, technically equivalent elements.
[0047] In practice the materials employed, provided they are compatible with the specific
use, and the dimensions and the contingent shapes, may be any according to requirements
and to the state of the art.
[0048] The disclosures in Italian Patent Application No.
PD2010A000159 from which this application claims priority are incorporated herein by reference.
[0049] Where technical features mentioned in any claim are followed by reference signs,
such reference signs have been inserted for the sole purpose of increasing the intelligibility
of the claims and accordingly such reference signs do not have any limiting effect
on the interpretation of each element identified by way of example by such reference
signs.
1. A burner for professional or domestic gas cookers, particularly of the type of vertical-flame
burners adapted for cooking with woks and the like,
characterized in that it comprises
- a burner body (11) which is substantially annular and encloses a tubular chamber
(12) that lies in a substantially helical arrangement around a central axis (A) and
is provided with an access hole (13),
- a Venturi-type supply tube (14), which is connected to said body (11) and opens
onto said hole (13) to introduce the combustion gas into said chamber (12),
said body (11) being provided with
- upper outflow ports (15) for said gas, which open onto the face (16) of said body
(11) that is the upper one during use and are adapted to form a flame that is oriented
substantially along said central axis (A),
- central outflow ports (17) for said gas, which open onto said body (11) substantially
toward said central axis (A).
2. The burner according to claim 1, characterized in that said Venturi tube (14) defines, for said gas, an inflow direction (B), in said chamber
(12), which is substantially tangent to said central axis (A).
3. The burner according to one or more of the preceding claims, characterized in that said upper outflow ports (15) comprise orifices (18a, 18b) which are arranged substantially
circumferentially with respect to said central axis (A) and peripherally to said body
(11).
4. The burner according to claim 3, characterized in that said orifices (18a, 18b) comprise first orifices (18a) and second orifices (18b)
provided at different radial distances, said first orifices (18a), with respect to
said second orifices (18b), being offset circumferentially around said central axis
(A).
5. The burner according to one or more of the preceding claims, characterized in that said upper outflow ports (15) comprise an annular opening (19) which is peripheral
with respect to said body (11).
6. The burner according to one or more of the preceding claims, characterized in that said central outflow ports (17) are slot-shaped and are distributed substantially
uniformly on a wall (20) of said body (11) that is substantially frustum-shaped and
diverges upward, during use, and is substantially coaxial to said central axis (A),
which it faces.
7. The burner according to claim 6, characterized in said central outflow ports (17) lie substantially along planes (D) which are tangent
to a cylindrical surface (E) which has a selected radius and is coaxial to said central
axis (A).
8. The burner according to one or more of the preceding claims,
characterized in that said body (11) comprises
- a base (22), which comprises a bottom (23) shaped like a helical ramp, and a perimetric
collar (24),
- a cover (25), which comprises an annular portion (26) and said wall (20) and is
adapted to mate complementarily with said base (22).
9. The burner according to claim 8, characterized in that said orifices (18a, 18b) open onto said annular portion (26), which has a peripheral
circular flap (27) that is adjacent to said orifices (18a, 18b), for resting in a
contoured seat (28) provided at the edge (29) of said collar (24), said flap (27)
and said edge (29) forming said annular opening (19), slits (30) for connection between
said chamber (12) and said annular opening (19) being furthermore provided, below
said flap (27), in order to feed said gas thereto so as to form a curtain of pilot
flame to ignite said gas that exits from said orifices (18a, 18b).