A gas burner

Abstract

 A gas burner comprises a hollow body (11, 13, 14) having an inlet (15) and a perforated outlet region (21). A baffle sheet (44) is provided behind the outlet region at a substantially constant spacing from it of about 2.5mm. The baffle sheet (44) includes apertures (27) to permit gas flow therethrough and extends over the whole of the outlet region (21).

Description

[0001] The invention relates to a gas burner.

[0002] A known gas burner is disclosed in European patent application no. 0172945. This discloses a gas burner having a tubular burner housing and a gas air mixing tube mounted co-axially within the housing. In the top surface of the burner housing, a pre-determined pattern of burner apertures is provided, the pattern consisting of an array of slots and holes. This is one example of a burner of this type. In this type of burner there may be a problem caused by turbulence in the gas flow leading to an uneven flow of gas through the burner apertures. This can cause the burner flame to "jump" thus resulting in noise which may be undesirable.

[0003] According to the invention there is provided a gas burner comprising a hollow body having an inlet and a perforated outlet region and a baffle provided in the body, the baffle lying closely adjacent the outlet region so as to extend over at least a substantial part of the outlet region, the baffle including apertures to permit fluid passage therethrough.

[0004] It has been found that use of a closely spaced baffle results in a very quiet and evenly burning burner.

[0005] Preferably the baffle and outlet region are spaced apart by a mean spacing of between 2mm and 3mm.

[0006] The baffle may be provided at a mean spacing of between about 2.4mm and 2.6mm from the outlet region and preferably is provided at a mean distance of about 2.5mm from the outlet region. This spacing has been found to give optimum results.

[0007] The baffle is preferably such that the gas passing into the inlet must pass through the baffle to reach the outlet region.

[0008] Although the baffle may be, for example, of a corrugated form, the baffle is preferably provided at a substantially constant spacing from the outlet region.

[0009] The baffle may take any suitable form but preferably comprises a sheet having apertures defined therein. The sheet apertures may be of any cross-section in relation to the perforations in the outlet region, but preferably are of larger cross-section than the perforations in the outlet region. This arrangement provides a good even flow of gas and also means that the baffle sheet may be a less complex item to manufacture than the outlet. The apertures may be arranged in longitudinal rows and the perforations may also be arranged in longitudinal rows.

[0010] Preferably, there are twice as many rows of perforations in the outlet region as of apertures in the baffle sheet.

[0011] The perforations of the outlet region may be arranged as a regular array of holes and slots. Preferably the holes and slots are provided alternately as a slot and then a row of holes and then a slot and so on.

[0012] In one preferred embodiment, the outlet region is cylindrical. In another preferred embodiment the outlet region may be part cylindrical and in that case the burner may be generally flat. In the case where the outlet region is part cylindrical and the baffle is provided as an apertured sheet, the sheet apertures preferably decrease in size in the circumferential direction from the centre of the baffle. This arrangement provides a lower rate of flow at the edges of the burner which is desirable in reducing noise from the burner.

[0013] The outlet region may be an integral part of the body or may be provided in a separate component attached to the remainder of the body in any suitable way.

[0014] A spreader plate may be provided between the baffle plate and the inlet.

[0015] The gas burner is preferably a pre-mixed gas burner.

[0016] Two embodiment of the invention will be described by way of example and with reference to the accompanying drawings in which:

Fig. 1 is a top plan view of the first embodiment;

Fig. 2 is an end view in cross-section of the first embodiment;

Fig. 3 is a side view in cross-section of the first embodiment;

Fig. 4 is an underneath plan view of the first embodiment partially cut away in two levels; and

Fig. 5 is a perspective view partially cut away to the second embodiment.

[0017] The embodiment 10 comprises a formed lower tray 11 having a broad flange 6 extending outwardly from its walls 5. A flat spreader plate 12 is provided on top of the tray 11 and a top skin 13 is provided on top of the spreader plate 12. The spreader plate 12 and the top skin 13 overlap the flange 6. The side edges 4 of the flange 6 are crimped over to secure the perforated foil 13 and spreader plate 12. Additionally fasteners such as rivets 3 are provided in apertures 9 formed in the crimped region. Thus, a lower chamber is formed between the tray 11 and the spreader plate 12 and an upper chamber 7 is formed between the top skin 13 and the spreader plate 12. The upper chamber 7 is sealed at each end by end caps 14. The end caps 14 are generally in cup form and are inserted between the top skin 13 and spreader plate 13 so as to be outwardly facing. The lower edges 1 of the end caps protrude from the top skin 13 and the side edges of the flange 6 are crimped therearound to hold the end caps 14.

[0018] An inlet aperture 15 is provided in the lower surface of the tray 11. Also in the lower chamber is provided a transverse baffle 16. The baffle 16 is V-shaped in cross-section and is mounted along its lower edge to the floor of tray 11.

[0019] Secured to the underside of the tray 11 is a fan locating plate 17 to which is attached a fan locating bracket 18. A fan (not shown) in use is mounted on the bracket to drive the mixed gases into the inlet 15.

[0020] The top skin 13 comprises upstanding walls 19 connected by an upper part 21. A pattern of perforations 20 is provided in the upper part 21. Fig. 1 shows only some of the perforations which extend in a rectangular array in the pattern shown over almost the entire upper part 21 of the top skin 13. The perforations 20 are provided in transverse rows 22 each row comprising a transverse slot 29 followed by a line of three round holes 30 and that pattern being repeated across row 22. The line of holes 30 is of the same length as the transverse slot 29. Adjacent rows 22 are offset by half a pattern repeat so that a transverse slot 29 in one row 22 is alongside a line of holes 30 in the adjacent row.

[0021] Two end strips 23 are provided at each end of the upper part 21 of the foil 13. Each end strip 23 extend over sthe end of the foil 13 and the top wall of the end cap 14 to create a seal between these components.

[0022] A baffle sheet 24 is provided in the upper chamber. The baffle sheet 24 is provided at a substantially constant spacing of about 2.5mm between the upper surface of the baffle sheet 24 and the upper surface of the top skin 13. The thickness of the top skin 13 is about 0.25mm and the thickness of the baffle sheet 24 is about the same. The edges 25 of the sheet 24 lie in contact with the foil sides 19 and are secured thereto. The baffle sheet 24 is held in position in relation to the upper part of the foil 13 by two longitudinal angle sections 26 which are mounted between the end caps 14. Between the angle sections 26, five longitudinal rows 31 of equally spaced apertures 27 are provided. The apertures 27 in each row 31 are circular and are of the same size. The apertures 27 in the central row are larger than in the rows adjacent them which in turn are larger than the apertures in the outer rows.

[0023] Longitudinal slots 28 are provided adjacent the edges of the spreader plate 12 to allow communication between the upper and lower chambers 7,8.

[0024] In use, pre-mixed gas and air are driven through the inlet 15 by a fan and the mixture spreads through the lower chamber 8 and enters the upper chamber 7 through the longitudinal apertures 28. At the upper chamber 7, the mixture passes through the baffle sheet 24 and through the perforations 20 in the upper surface of the top skin 13 to burn.

[0025] Fig. 5 shows a second embodiment in which the burned 40 is generally cylindrical having a cylindrical perforated outer skin 41 bounded by circular end caps 42 in one of which is formed an axially disposed inlet opening 43. The outer skin 41 has the same pattern of holes 30 and slots 29 as the upper part 21 of the top skin 13 in the first embodiment. A cylindrical baffle sheet 44 is provided behind the perforated outer skin 41 and the outer surface of the baffle sheet 44 is spaced from the outer surface of the outer skin 41 by about 2.5mm. The baffle sheet 44 includes a regular rectangular array of round apertures 45 of equal size.

[0026] In use, pre-mixed gas and air is introduced through the inlet 43 and passes through the apertures 45 in the baffle sheet 44 to the holes 30 and slots 29 in the outer skin 41 on exit from which the mixture is burnt.

Claims

1. A gas burner comprising a hollow body (11, 13, 14) having an inlet (15) and a perforated outlet region (21) and a baffle (24) provided in the body, the baffle lying closely adjacent the outlet region so as to extend over at least a substantial part of the outlet region (21), the baffle (24) including apertures (27) to permit fluid passage therethrough.

2. A gas burner as claimed in claim 1, characterised in that the baffle (24) and outlet region (21) are spaced apart by a mean spacing of between 2mm and 3mm.

3. A gas burner as claimed in claim 2, characterised in that the baffle is provided at a mean spacing of between about 2.4mm and 2.6mm from the outlet region (21).

4. A gas burner as claimed in claim 3, characterised in that the baffle is provided at a mean distance of about 2.5mm from the outlet region.

5. A gas burner as claimed in any preceding claim, characterised in that the baffle (24) is arranged such that the gas passing into the inlet (15) must pass through the baffle to reach the outlet region (21).

6. A gas burner as claimed in any preceding claim, characterised in that the baffle (24) is provided at a substantially constant spacing from the outlet region (21).

7. A gas burner as claimed in any preceding claim, characterised in that the baffle (24) comprises a sheet having apertures (27) defined therein.

8. A gas burner as claimed in any preceding claim, characterised in that the apertures (27) in the baffle are of larger cross-section than the perforations (20) in the outlet region (21).

9. A gas burner as claimed in any preceding claim, characterised in that the apertures (27) in the baffle (24) are arranged in longitudinal rows.

10. A gas burner as claimed in any preceding claim, characterised in that the perforations (20) in the outlet region are arranged in longitudinal rows.

11. A gas burner as claimed in claim 10, when dependent on claim 9, characterised in that there are twice as many rows of perforations (20) in the outlet region (21) as of apertures (27) in the baffle (24).

12. A gas burner as claimed in any preceding claim, characterised in that the perforations (20) of the outlet region (21) are arranged as a regular array of holes and slots.

13. A gas burner as claimed in claim 12, characterised in that the holes and slots are provided alternately as a slot and then a row of holes and then a slot and so on.

14. A gas burner as claimed in any preceding claim, characterised in that the outlet region is part cylindrical.

15. A gas burner as claimed in claim 14, characterised in that the outlet region (21) is wholly cylindrical.

16. A gas burner as claimed in claim 14, characterised in that the burner is generally flat.

17. A gas burner as claimed in claim 16, characterised in that the apertures in the baffle decrease in size in the circumferential direction from the centre of the baffle.

18. A gas burner as claimed in any preceding claim, characterised in that the outlet region is provided in a separate component (13) attached to the remainder of the body (12, 14).

19. A gas burner as claimed in any preceding claim, characterised in that a spreader plate (12) is provided between the baffle (24) and the inlet (15).

20. A gas burner as claimed in any preceding claim, characterised in that the gas burner is a pre-mixed gas burner.

Drawing