GB2219389A

GB2219389A - Pressure jet burner

Info

Publication number: GB2219389A
Application number: GB8908473A
Authority: GB
Inventors: William Henry Deryk Morris; Michael Peter Walshe
Original assignee: Individual
Current assignee: Individual
Priority date: 1988-06-03
Filing date: 1989-04-14
Publication date: 1989-12-06
Anticipated expiration: 2009-04-14
Also published as: GB2219389B; GB8908473D0

Abstract

A pressure jet burner 10, suitable for a domestic cooker, comprises a housing 11 supporting a blast tube 19 above a fan 13. The blast tube 19 is disposed towards a front end 22 of the housing and projects rearwards. A motor 16 and pump 17 are provided to supply fuel oil to the blast tube via line 20. The blast tube 19 is inclined upwardly and receives air from the fan 13 via a generally horizontal air duct 14 and an expansion chamber 15, the air entering the fan from inlets 21. <IMAGE>

Description

The present invention relates to improvements in pressure jet burners of the type which use oil/gas as fuel.

Various systems for burning oil fuel to release useful heat have been in use for very many years. Some of these systems rely on vapourising oil from a heated surface or from a wick. These systems also use manual ignition and cannot be said to be fully automatic but they do have the virtue of silence. All other forms of automatically controlled oil burners rely on the use of a fan to force the required quantity of air into a combustion chamber together with a pump to force the oil fuel, usually at a substantial pressure into the same area. Any such automatically-controlled oil burner will also require a means of ignition, contain safety devices, and a suitzble control system.

Known limitations of this type of oil burner, (which are generally classified as "pressure-jet" burners) include a relatively high noise level, a tendency for the working parts of the burner including the oil pump and the fan to work at too hot a temperature, difficulty in achieving precise control of the airflow from the fan because the final expulsion of the air from the fan occurs at a distance that is much less than the diameter of the fan, an unduly turbulent and fluctuating air supply, and an air supply with. no means of receiving significant degree of preheating although it is well known that combustion conditions are improved when the incoming air is properly preheated.

It is an object of the present invention to mitigate the above problems.

According to the invention there is provided a pressure jet burner comprising a housing supporting a blast tube above an air supply means, the blast tube being disposed towards a front end of the housing and projecting rearwardly, and means for supplying a fluid type fuel to the blast tube.

An embodiment of the invention will now be described by way of example, with reference to the accompanying drawings in which: Figure 1 is a perspective view of a pressure jet burner according to the invention; Figure 2 is a diagrammatic sectional view of the burner of Figure 1 in a domestic cooker/boiler; and Figure 3 is a diagrammatic cross-sectional view of the pressure jet burner of Figure 1.

Referring now to the drawings wherein similar numerals have been used to indicate like parts, there is shown therein, a pressure jet burner generally indicated at 10 according to the invention. The burner 10 comprises a generally hollow housing 11 having a rear part 12 which contains a fan 13, a generally horizontal air duct 14 and an expansion chamber 15. The fan 13 is driven by a motor 16 mounted on the rear part 12, and the motor 16 also drives a fuel pump 17. Fuel is supplied to the fuel pump 17 via a conduit 18 and the fuel is delivered from the pump 17 to a nozzel (not shown) in a blast tube or combustion chamber 19 via a feed line 20. As shown, the blast tube 19 is generally cylindrical and is mounted adjacent the front end 22 of the housing on the expansion chamber 15 and is inclined angularly upwards and in the direction of the rear part 12 of the housing 11.The blast tube 19 projects upwardly at an angle of between 100 to 800 relative to the horizontal and more preferably at an angle of between 250 to 600. The rear part 12 of the housing 11 has a number of small apertures 21 to enable air to be drawn into the housing 11.

The blast tube 19 also includes conventional ignition electrodes (not shown) to ignite the fuel/air mixture. The apparatus will also include a conventional control system which is not shown in the drawing and which may include an on/off switch, thermostat control, power supply for the motor and ignition electrodes and a timer.

In Figure 2 the pressure jet burner is shown located in the ash pit 30 of a conventional domestic solid fuel cooker. As shown, the burner 10 is located in the ash pit region 30 with the rear part 12 innermost so that the blast tube 19 is directed rearwards into the zone 31 to be heated. The burner 10 is shielded from the heating zone 31 by means of a ceramic heat shield 32 which is supported on the horizontal air duct part 14.

In addition, the ceramic heat shield 32 may be supported on a sheet of steel (not shown).

A slidable damper plate 40 is provided to control the flow of air from the fan 13 to the expansion chamber 15. The damper 40 is provided to adjust the size of a variable aperture 41 between the rear part 12 and horizontal part 14 of the housing 11. The damper 40 comprises a flat rectangular metal damper plate having an upstanding boss 43 which has a threaded aperture 44 in which a threaded rod 45 is engaged. The threaded rod 45 is rotatably secured to the front and rear end walls 46, 47 respectively of the housing 11.

The rear end 48 of the rod 45 passes through an aperture 49 in the rear end wall 47 of the housing 11 and has an enlarged end collar 50 to retain it in place. Similarly, the front end 51 of the rod 45 passes through an aperture 52 in the front wall 46 of the housing 11 and has an enlarged end collar 53 to retain it in place. The front end 51 of the rod 45 also has an operating knob 54 fixed thereto to enable a user to readily rotate the rod 45. Thus, rotation of the rod 45 by rotating the knob 54, causes the rod 45 to drive the damper plate 42 forwards or rearwards to adjust the size of the aperture 41 and thus control the airflow from the fan 13. A suitable stop member 60 is provided to limit the forward movemet of the damper plate 42.

In use, with the motor 16 energised, the pump 17 supplies fuel to the nozzle (not shown) in the blast tube from where it is emitted in the form of a fine spray, and is ignited by the electrodes (not shown).

With the fan 13 in operation, air is drawn into the housing 11 via the apertures 21 and as the air must enter the ash pit area 30 via the ash it door 40, the air travels in the direction of the arrow A thus acting to cool the motor 16. The air is also preheated in this way.

The air entering the apertures 21 is directed upwardly through the variable aperture 41, into the rear of the horizontal air duct 14 and into the expansion chamber 15. The effect of the expansion chamber 15 is to reduce the velocity of the air flow while maintaining the static pressure. It has been found that this velocity reduction reduces the noise level from the combustion head or blast tube 19.

Because of its low noise level and efficient use of fuel the invention may be used in cookers designed for oil firing or as a combustion unit designed to permit the use of oil fuel where solid fuel had previously been used. The invention can also be used to advantage for any application where a particularly quiet and effective oil burner is needed.

Claims

CLAIMS:

1. A pressure jet burner comprising a housing supporting a blast tube above an air supply means, the blast tube being disposed towards a front end of the housing and projecting rearwardly, and means for supplying a fluid type fuel to the blast tube.

2. A burner as claimed in claim 1, wherein the air supply means comprises a fan disposed rearwards of said blast tube.

3. A burner as claimed in claim 1 or 2, whereinthe blast tube is inclinded angularly upwardly.

4. A burner as claimed in claim 2 or 3, wherein the blast tube communicates with the fan via a generally horizontal air duct.

5. A burner as claimed in claim 4 wherein the blast tube communicates with the generally horizontal air duct via an expansion chamber, disposed adjacent a front end of the horizontal air duct.

6. A burner as claimed in claim 4 or 5, wherein the fan is arranged to direct air upwardly through a variable aperture into the rear end of the generally horizontal air duct.

7. A burner as claimed in claim 6, wherein the variable aperture is adjustable in size by means of a slidable damper plate.

8. A burner as claimed in claim 7, wherein the damper plate is engaged with a rotatable threaded rod passing through the housing such that rotation of the rod causes linear movement of the damper plate.

9. A burner as claimed in claim 8 wherein the rod has an operating knob at the front end of the housing.

10. A pressure jet burner substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.