FR2800845A1 - GAS BURNER FOR DOMESTIC HOB - Google Patents

Abstract

The invention relates to a gas burner (1) for a domestic hob, and more specifically to a star burner with secondary air. The burner according to the invention comprises a burner head (3) with several branches (4) provided with 'orifices (10) for the primary mixture, and extending from a central body (5), the head being slightly raised in relation to a hearth plate (2). It further comprises a passage for the primary mixture in communication with said head, and a secondary air passage independent of the passage for the primary mixture. The secondary air passage takes place through an opening (8) in the hearth plate, positioned substantially under the central body of the head. The burner according to the invention further comprises means (9) for deflecting the secondary air making it possible, between two branches, to fold at least part of the secondary air flow along the branches, substantially above the orifices. .

Description

The invention relates to a gas burner for a hob.

  domestic, and more specifically a secondary air star burner.

  In so-called secondary air burners, a partial premixing of combustible gas and air is carried out upstream of the flames and the additional air necessary for combustion is taken from the ambient air located in the vicinity of the flames. The secondary air is therefore the air taken in the vicinity of the flames as opposed to the so-called primary air premixed with gas upstream.

flames.

  The gas burners of a domestic cooktop 1o include a burner head located above a hearth plate. The air and gas premix (primary mixture) escapes through orifices located at the periphery of the burner head. This type of burner generally requires that a free space be provided in the vicinity of the flames so as not to disturb the arrival of secondary air. If the secondary air in fact does not arrive in the vicinity of the flames in sufficient quantity, the combustion is incomplete and produces toxic gases, in particular carbon monoxide (CO). This free space imposes a minimum height between the hearth plate and the flames and between the flames and the bottom of the container. Sufficient free space also imposes simple shapes for the burner head which

is generally circular.

  However, a better distribution of the temperature is obtained on the bottom of the container in the so-called star gas burners. The term 'star' is taken here broadly. It is any burner comprising a burner head with several branches which extend from a central body, these branches being able to take any shape. In this type of burner, the branches are provided with outlets for the primary mixture which are the outlets for the flames. On the other hand, we seek to decrease the height between the hearth plate and the level of the flames, in order to present more aesthetic burners, and to reduce the height between the level of the flames and the container, in order to gain in efficiency. heating. Self-supporting burners can thus be obtained, that is to say burners on the head of which the container can be placed directly, and which therefore no longer require a grate to place the container. In all these cases, the problem of

  supply of secondary air to the flames.

  The invention solves these difficulties and proposes a gas star burner, the height between the hearth plate and the flame level as well as between the flame level and the container can be reduced to a minimum, while ensuring a optimal supply of flames with secondary air. For this, the invention relates to a burner for a cooktop comprising a burner head with several branches provided with orifices for the primary mixture, and extending from a central body, the head being slightly raised relative to a plate. hearth, a passage for the primary mixture Io in communication with said head, and a secondary air passage independent of the passage for the primary mixture, characterized in that said passage is effected by an opening in the hearth plate , positioned substantially under the central body of the head, and in that it further comprises means for deflecting the secondary air allowing, between two branches, to fold down at least part of the flow of secondary air

  along the branches, substantially above the orifices.

  Thus, in the burner according to the invention, even if it is a self-supporting burner, the supply of secondary air can be carried out both from below the flames, thanks to the secondary air which s flows under the branches, and over the flames, thanks to the air

  secondary which is deflected along the branches.

  Other advantages and characteristics of the invention will appear

  on reading the description which follows, illustrated by the figures which

  represent: - Figure 1, a view of an example of a burner according to the invention - Figure 2, a partial view of another example of a burner according to the invention; - Figure 3, a top view of an embodiment of the

burner according to the invention.

  In these figures, the homologous elements are indexed by the

same benchmarks.

  FIG. 1 represents a view of an example of a burner according to the invention. The burner 1 is mounted on a hearth plate 2. It comprises a burner head 3 with several branches 4 extending from a central body 5, and thus forming a star burner. The shape of the central body, as well as that of the branches and the number of these branches is arbitrary. For example, as in the example of FIG. 1, the central body has a substantially circular shape and the branches, of elongated shape, five in number, are distributed regularly along the circumference of the central body 5. The branches are provided with ports for the primary mixture. The shape of these orifices defines the shape of the flames. In the example of Figure 1, the orifices are positioned in the same plane, defining a flame level 6. The head can be formed in one piece, or a first piece forming a gas train and covered by a hat of shape o substantially identical to that of the ramp and covering it. The head 3 is slightly raised relative to the hearth plate 2, for example by means of feet 7 placed at the ends of the branches. The burner also conventionally comprises a passage for the primary mixture in communication with the head for supplying the primary mixture with the orifices. It can also include an ignition or flame detection device, not shown here, or other conventional means of

  operation of a gas burner.

  According to the invention, the burner further comprises a secondary air passage independent of the passage for the primary mixture and which takes place through an opening 8 in the hearth plate. This opening is positioned substantially under the central body of the head in order to provide secondary air to the flames of all the branches. As the head is raised relative to the hearth plate, the secondary air coming from the opening can flow under the branches, thus allowing the flames to be supplied with secondary air from below. This flow is materialized

  in Figure 1 by arrows in thin line.

  According to the invention, the burner 1 further comprises deflection means which allow, between two branches, to fold at least part of the secondary air flow along the branches, substantially above the orifices. These deflection means make it possible to at least partially deflect the secondary air flow coming from the opening 8, thus creating a supply of flames with secondary air from above. They can be placed on the burner head, or directly integrated into it. For example, they are formed, as illustrated by FIG. 1, substantially horizontal fins 9, situated in a plane above that of the orifices and which extend between the branches, starting from the central body 5 of the burner. Advantageously, the opening 8 for the passage of secondary air extends beyond the central body 5 of the burner, which makes it possible to leave between the branches secondary air inlet passages not covered by said central body. Thus, the secondary air, for example injected by an injection system located under the hearth plate, can be distributed in the hollow of each branch of the burner, parallel to its axis. Between the branches, along the central body of the burner, a large part of the secondary air flow follows a substantially vertical flow, then is deflected by the deflection means, to form a secondary air flow along the branches, at the - above level 6 of the flames. this flow is materialized on the

  Figure 1 by arrows in thick line.

  Thus in the burner according to the invention, the secondary air supply to the flames is carried out both from below and from above. This effect is particularly advantageous for example in the case of wide and flat flames, since in this case the secondary air has very little

  access to the sides of the flame.

  Alternatively, the passage for the primary mixture is effected by a manifold (not shown) in communication with the central body, and centered substantially in the opening. The secondary air passage therefore takes place through the space around the manifold. Advantageously, the collector being of substantially circular section, centered on the opening, the space is homogeneous around the collector, and the secondary air can be

  uniformly distributed in the hollow of each branch.

  Figure 2 shows a partial view of a burner according to the invention. There is a burner head 3 with several branches. 4 extending from a central body 5, and thus forming a star burner. In Figure 2, only two branches are shown. The branches are provided

  orifices 10 for the primary mixture, defining a level of flames 6.

  In the example of Figure 2, these holes are rectangular, giving flames 1 1 flat and wide. There are also fins

  9 forming the deflection means described above.

  In this example, the burner 1 further comprises means for channeling the secondary air allowing, between two branches, a substantially vertical flow of the air flow along the central body. The applicant has in fact shown that the channeling of the secondary air flow along the central body, that is to say in the hollow which separates two branches, makes it possible to improve the supply of flames with secondary air from above. As in the previous figure, the secondary air flow from above is materialized by arrows in thick line, while the secondary air flow from below is materialized by arrows

in thin lines.

  The channeling means are formed for example of a ring io positioned on the hearth plate, substantially centered with respect to the central body of the burner, and having a set of high slots 12, each high slot being positioned between two branches and having a substantially vertical wall, allowing between two branches the substantially vertical flow of the secondary air flow. In the example of FIG. 2, the opening for the passage of secondary air is substantially circular, of

  so that the ring can fit around the periphery of the opening.

  Under each branch, the ring can also have a low slot whose height is such that it does not prevent the flow of secondary air under the branch. The low slots have above all an overfill function. Indeed, if liquid is spilled from a container in place on the burner, it will not be able to seep into the opening of the hearth plate, thanks to the presence of the high slots between the branches, and to that

  low slots under the branches.

  The Applicant has shown that a good flow of secondary air between the branches was obtained for example with a height of a high slot slightly less than the height of the orifices 10, as illustrated in FIG. 1, thus allowing a level of flames appreciably located midway between the secondary air flows from below and

from above.

  FIG. 3 represents a top view of an example of a burner according to the invention. The burner 1 is here a star burner with five branches (4), distributed around a central body 5 of substantially circular shape. The head, formed of the central body and the branches, is slightly raised relative to the hearth plate by means of the feet 7, positioned at the ends of the branches. The passage for the primary mixture is ensured by a manifold 14, centered on the opening 8 in the hearth plate 2 and leaving, all

  around, a space for the passage of secondary air.

  In this example, the means for deflecting the secondary air are formed by a ring 15, positioned on the head of the burner, and whose external diameter is greater than that of the central body, thus making it possible to reduce the secondary air. along the branches, substantially above the orifices. As in the previous example, the arrows in thin line symbolize the flow of secondary air under the branches, to feed the flames from below, while the arrows in line

  o thick symbolize supply of flames with secondary air from above.

  In this example, means for channeling the secondary air are provided. A ring, of the type described above, is for example positioned on the periphery of the opening. It includes high slots 12 between the branches, and low slots 13 under the branches. The high slots make it possible to strengthen between the branches, the

  secondary air flow that feeds the flames from above.

  Of course, the invention is not limited to the examples described above. In particular, it applies to any form of star air burner with secondary air and allows, in a simple manner, a very good supply of the flames with secondary air, whatever the form of these flames.

Claims (8)

  1- Burner (1) for a hob comprising a burner head (3) with several branches (4) provided with orifices (10) for the primary mixture, and extending from a central body (5), the head being slightly raised relative to a hearth plate (2), a passage for the primary mixture in communication with said head, and a secondary air passage independent of the passage for the primary mixture, characterized in that said passage s '' effect by an opening (8) in the hearth plate, positioned substantially under the central body of the head, and in that it further comprises means for deflecting (9) the secondary air allowing, between two branches, to cast off at least part of the stream   of secondary air along the branches, substantially above the orifices.   2- Burner according to claim 1, characterized in that said opening extends substantially beyond the central body of the burner, leaving between two branches of the secondary air inlet passages not covered by said body.   3- Burner according to one of the preceding claims, characterized   in that said deflection means comprise substantially horizontal fins (9), positioned in a plane situated above the orifices for the primary mixture and which extend between two branches,   from the central body of the burner.   4- Burner according to one of claims 1 or 2, characterized in   that the central body of the burner being of substantially circular shape, said deflection means are formed of a ring (15) positioned on the head of the burner, centered on said central body, of substantially external diameter   higher than that of the central body.   - Burner according to one of the preceding claims, characterized   in that the passage for the primary mixture is effected by a manifold in communication with the central body and centered substantially in said opening, the passage of secondary air taking place in the space around the manifold.   6- Burner according to one of the preceding claims, characterized   in that it further comprises means for channeling the secondary air allowing between two branches, a substantially vertical flow of the flow secondary air.   7- Burner according to claim 6, characterized in that said channeling means are formed of a ring positioned on the hearth plate, substantially centered relative to the central body of the burner, and having a set of high slots (12) , each high slot being positioned between two branches and having a substantially vertical wall, allowing between two branches the substantially vertical flow secondary air flow.   8- Burner according to claim 7, characterized in that the height of the slots between two branches is slightly less than that   holes in the burner head.   9- Burner according to one of claims 6 or 7, characterized in   that the ring also has under each branch a bottom slot (13), said bottom slot having an anti-overflow effect and being high   such that it does not prevent the flow of secondary air under the branch.   - Burner according to one of claims 7 to 9, characterized in that   that the opening being circular, the ring fits on the periphery of the opening.