Patent Application
20190024941
The present invention relates to a totally aerated combustion burner (also called “all primary air burner”) which is provided with: a burner body which is supplied therein with air-fuel mixture; and a combustion plate part which covers an open surface of the burner body.
Conventionally, in this kind of totally aerated combustion burner, there is known an art in which a combustion plate part is constituted by: a burner frame in a shape of a picture frame; a metal-fiber knit (i.e., a metal knit formed of a heat resistant metal fiber) which is disposed to cover, from a burner-body side, an opening enclosed by the burner frame; and a distribution plate which has formed therein a multiplicity of distribution holes and which sandwiches the metal-fiber knit between the burner frame and the distribution plate. The air-fuel mixture supplied to the inside of the burner body is arranged to be ejected through the distribution holes and the metal-fiber knit (see, for example, JP-A-2014-9839). In this arrangement, on the opening peripheral part of the burner frame which is positioned on the same surface level as the opening, the metal-fiber knit and the distribution plate are spot-welded together.
If the metal-fiber knit and the distribution plate are spot-welded together, heat is likely to be transmitted from the metal-fiber knit to the distribution plate through the welded positions. In addition, since the metal-fiber knit will rise to a considerably elevated temperature during combustion, the distribution plate will also rise to an elevated temperature due to heat transmission through the welded positions, thereby causing high possibility of backfire.
In view of the above-mentioned points, this invention has a problem of providing a totally aerated combustion burner which is arranged to be able to restrain the heat transmission from the metal-fiber knit to the distribution plate.
In order to solve the above problem, this invention is a totally aerated combustion burner comprising: a burner body which is supplied therein with air-fuel mixture; and a combustion plate part which covers an open surface of the burner body. The combustion plate part is constituted by: a burner frame in a shape of a picture frame; a metal-fiber knit which is disposed to cover, from a burner-body side, an opening enclosed by the burner frame; and a distribution plate which has formed therein a multiplicity of distribution holes and which sandwiches the metal-fiber knit between the burner frame and the distribution plate. Only the metal-fiber knit is spot-welded to that opening peripheral part of the burner frame which is positioned on a same surface level as the opening, and the distribution plate is spot-welded to that portion of the burner frame which is offset from the opening peripheral part toward the burner-body side.
According to this invention, the distribution plate is spot-welded to that portion of the burner frame which is away from the opening peripheral part toward the burner-body side, heat transmission from the metal-fiber knit to the distribution plate will be restrained. As a consequence, the distribution plate will not be raised to such an elevated temperature, and backfire can effectively be prevented.
By the way, that portion of the burner frame to which the distribution plate is spot-welded may be a side-plate part which is bent from the opening peripheral part toward the burner-body side, or may be an outward-bent stepped part which is provided in a middle of a side-plate part which is bent from the opening peripheral part toward the burner-body side.
A combustion apparatus illustrated in
The heat exchanger 3 is constituted by a fin-tube type of heat exchanger having: a multiplicity of fins 31; and a plurality of heat absorbing tubes 32 which penetrate through these fins 31. On outside surfaces of laterally one-side and the opposite-side side plates 23, 24 of the combustion box 2, there are mounted a plurality of connection covers 33 which define, together with each of the side plates 23, 24, connection passages for the adjoining two heat absorbing tubes 32, 32. All of the heat absorbing tubes 32 are thus connected in series with each other. In addition, a water inlet port 34 is disposed in the connection covers 33 which define, between the laterally opposite-side side plate 24, a connection passage to be connected to an upstream-end heat-absorbing tube 32.
Further, on an inside of that portion of the rear-side side plate 25 of the combustion box 2 which is above the heat exchanger 3, there are respectively vertically arranged three pieces of first water passages 51, made of tubes, in a manner to be in contact with the side plate 25. Also on an inside of that portion of the front-side side plate 26 of the combustion box 2 which is above the heat exchanger 3, there are respectively vertically arranged three pieces of third water passages 53, made of tubes, in a manner to be in contact with the side plate 26. Further, on an outside surface of the laterally one-side side plate 23 of the combustion box 2, there are mounted: an inlet-side header cover 51 which defines, together with the side plate 23, a connection passage between the vertically arranged three pieces of first water passages 51 and the downstream-end heat absorbing tube 32 of the heat exchanger 3; and an outlet-side header cover 52 which defines, together with the side plate 23, a connection passage for the vertically arranged three pieces of third water passages 53. The outlet-side header cover 52 is provided with a hot water outlet port 53. The laterally opposite-side side plate 24 of the combustion box 2 is provided, as shown in
The front-side side plate 26 of the combustion box 2 has mounted thereon an electrode component 6 having an ignition electrode 61, a ground electrode 62, and a flame rod 63, all penetrating the side plate portions between No. 1 and No. 2, i.e., totally two, third water passages 53, 53 counted from the top to thereby protrude into the combustion box 2. By the way, the electrode component 6 is additionally provided with an inspection window 64 which enables visual confirmation inside the combustion box 2.
Detailed description will now be made of a totally aerated combustion burner 1. The burner body 11 has opened therein an inlet port 113 to which is connected a fan 4 for supplying the air-fuel mixture. The inlet port 113 has mounted therein a check valve 13 which prevents, at the time of stopping of the fan 4, the air-fuel mixture staying inside the burner body 11 from flowing back toward the fan 4. The check valve 13 is constituted by: a resin valve box 131 to be fitted into the inlet port 113; and a resin valve plate 132 mounted in that opening of the valve box 131 which faces inside the burner body 11 so as to be swingable about an axis between opened and closed postures.
With reference also to
The burner frame 121 has: an opening peripheral part 121a which is positioned on the same surface level as the opening 122; a side plate part 121b which is bent from the opening peripheral part 121a to the burner-body 11 side (i.e., upward); and a frame flange part 121c which protrudes outward from an upper end of the side plate part 121b. Then, the frame flange part 121c is sandwiched between the body flange part 112 and the connection flange part 22. A packing 7 is further interposed between the frame flange part 121c and the body flange part 112, thereby securing the sealing characteristics. Further, a thermal insulation material 8 is attached to the lower surface of the frame flange part 121c.
The metal-fiber knit 123 is spot-welded to the opening peripheral part 121a at predetermined circumferential spacing in a state in which the peripheral part of the metal-fiber knit 123 is overlapped with an upper surface of the opening peripheral part 121a of the burner frame 121. In
By the way, it is conceivable to spot-weld the distribution plate 124 to the opening peripheral part 121a together with the metal-fiber knit 123. This idea, however, gives rise to the following disadvantage. In other words, since the heat is likely to be transmitted from the metal-fiber knit 123, through the welded points, to the distribution plate 124, the distribution plate 124 will rise to a considerably elevated temperature due to heat transmission from the metal-fiber knit 123 during combustion, thereby giving rise to backfire.
As a solution, in this embodiment, what is spot-welded to the opening peripheral part 121a is limited to the metal-fiber knit 123. Further, upward bent part 124b is formed by bending laterally both ends of the distribution plate 124. Then, the bent part 124b is spot-welded to the side plate part 121b, i.e., that portion of the burner frame 121 which is offset from the opening peripheral part 121a to the burner-body 11 side (i.e., to the upper side). In
Description will now be made of another embodiment of the combustion plate 12 with reference to
Descriptions have so far been made of embodiments of this invention with reference to the drawings. However, this invention shall not be limited to the above. For example, the totally aerated combustion burner of the above-mentioned embodiments has disposed the open surface 111 of the burner body 11 to look downward. This invention can also be applicable to a totally aerated combustion burner having disposed therein the open surface 11 to look upward.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2017-138842 | Jul 2017 | JP | national |
