Abstract:
There is provided a burner assembly for burning fuel in which the housing contains a nozzle orifice and a cleaning needle moveable into and out of the orifice. The needle is provided with permanent magnetic characteristics and is between a pair of movable magnets, which can be rotated to change poles so as to move the needle into and out of the orifice.

Description:
FIELD OF THE INVENTION 
     This invention concerns a burner assembly to be used in lightweight portable or stationary stoves for different liquid and gaseous fuels. 
     DESCRIPTION OF THE RELATED ART 
     This type of stoves using liquid or gaseous fuels have clogging problems caused by building up of the fuel itself in the nozzle orifice, such as coke formation, or of extraneous material. Then there is a need for cleaning this orifice. 
     This type of burners usually have a cleaning needle inside the orifice, which needle could be brought to penetrate the orifice to clean the orifice and then retracted to clear the orifice. One known method to move the needle in and out of the orifice is by means of a pinion, engaging a rack provided on a burner body carrying the needle. The pinion is handled from the outside of the burner. Another known method is to use a weighted needle which upon shaking enters the orifice with an in and out motion. The drawback of the first method is that there is a need for very exact fit between rack and pinion and the assemblage is troublesome. The second method deals with a device, that is more simple to produce and assemble. However it is difficult to handle especially when burning and could not at all be used in connection with heavier or stationary stoves. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a burner assembly for burning of liquid or gaseous fuel of different types. The burner assembly has a cleaning needle which is possible to move in and out of the nozzle orifice by means of magnetic force. The invention could be used in connection with lightweight stoves, more heavy stoves or stationary stoves. 
     When moving a magnet provided outside a burner assembly housing the magnetic needle inside the housing will move correspondingly, which imply that by means of the outside, movable magnet it is possible to move the needle up and down in the housing and thereby in and out of the nozzle orifice. 
     The needle is suitably provided on a needle body which per se could be a magnet or which could be provided with a built in, separate magnet. The magnet outside the housing could be a permanent magnet or a magnet of electromagnetic type. In this case it would be possible to have this electromagnetic type magnet capable of producing opposite magnet fields by shifting the magnetic polarization. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1 and 2 show schematically an isometric sectionally view of part of the invention in two positions respectively of the cleaning needle, 
     FIGS. 3-7 show schematically sequences of the operation of one preferable arrangement of the invention, 
     FIGS. 8-9 show schematically an operation sequence in a further arrangement of the invention and 
     FIGS. 10 and 11 show schematically isometric sectionally views of the invention in other embodiments. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 shows schematically in cross section a burner without the outside provided magnet or magnets, together forming the burner assembly according to the invention. 
     The burner consists of a housing  1  and a nozzle section  2 , attached to the housing  1  by means of threads. The housing  1  and the nozzle section  2  are enclosing a chamber  3  of cylindrical form, the upper end of which has a conical shape at the point forming a nozzle orifice  4 .  5  depicts a part of a fuel line to be connected to the fuel delivery system, not shown. The chamber  3  is occupied by a cylindrical needle body  6  provided with a cleaning needle  7 . The body  6  with the needle  7  is movable up and down in the chamber  3 , FIG. 1 shows the needle retracted in the chamber, leaving the orifice  4  open. 
     According to the invention the needle body  6  is of magnetic material forming a permanent magnet. It is also possible to have the body made in a non-magnetic material, in which a permanent magnet  6 ′ is incorporated, see FIG. 2, as an alternative. The poles of the body  6  as well as the magnet  6 ′ are designated S and N respectively. The rest of the burner assembly is made of a non-magnetic material, not influencing the body  6 , which have magnetical property. 
     In the example schematically shown in FIGS. 3-7 the burner according to FIG. 1 is forming a burner assembly including permanent magnets  8  and  9  provided upon a horizontally slidable device  10 , as shown in the figures. The slidable device  10  could be mounted in the stove or in a separate tool. The poles of the magnets  8 ,  9  are designated N and S respectively. 
     FIG. 3 shows the needle  7  retracted in the chamber  3 , leaving the orifice  4  open. The body  6  with the needle  7  is not influenced by the magnets  8 ,  9  and the body  6  is kept in this position by the gravitation. 
     FIGS. 4 and 5 show how the magnets  8 ,  9  are displaced by means of the slidable device  10  beneath the burner  1 . Firstly the magnet  8  is brought beneath the burner and the north pole N and south pole S of the body  6  and magnet  8  respectively attract each other (arrows F) . Further displacements of the device  10  will then bring the magnet  9  in a position beneath the burner  1  and its north pole N is placed beneath the north pole N of the body  6 . This means that a repulse force F (FIG. 5) is created between the magnet  9  and the body  6 , which inturn means that the body  6  is forced upwardly, whereby the needle  7  penetrates the orifice  4 , which now is being cleaned. 
     FIG. 6 shows how the device  10  with the magnets  8 ,  9  is retracted now again bringing the magnet  8  beneath the body  6  of the burner  1 , which means that an attraction force is created, retracting the body downwards and the needle  7  out of the orifice  4 , leaving this open and cleaned. 
     FIG. 7 shows how the device  10  has occupied its initially position with the magnets  8 ,  9  out of influence with the body  6 , as shown in FIG.  3 . 
     The use of the attraction force according to FIG. 6 is advantageous when the needle  7  is stuck in the orifice  4 . 
     The manoeuvering of the slidable device  10  with the magnets  8  and  9  could be done in several ways using no inventive steps and obvious for the man skilled in the art. 
     FIGS. 8 and 9 show the invention using only one magnet  11  on the slidable device  10 . When displacing the device  10  with the magnet  11  its north pole N will be placed beneath the north pole N of the body  6 , creating a repulse force (F). The difference compare to the arrangement according to FIGS. 3-7 is that the body  6  with the needle  7  will return to its lower position with the needle  7  out of the orifice  4  only by aid of gravity. 
     The needle  7  and needle body  6  in the housing  1  are mounted in a burner-head in a usual and known manner. A fuel line from the burner-head is connected to e.g. a fuel container, such as a fuel bottle. The fuel is a liquid or a gaseous fuel and could be white gas, diesel, kerosene etc. and LPG, butane, propane etc. respectively. The burner assembly should be mounted in a stove in a suitable manner, obvious to the man skilled in the art. 
       12  in FIGS. 1 and 2 depict a slot to be engaged by a screwdriver to dismount the nozzle section  2 . 
     Instead of a separate permanent magnet it is also possible to use an electromagnetic magnet e.g. in the form of a solenoid  16 , see FIG.  8 . Mounting this beneath the housing  1  the body  6  with its needle  7  could be forced up and down in the housing  1  just by shifting the magnetic polarization of the solenoid. 
     In the example shown in the FIG. 11 there is a separate permanent magnet  13  mounted beneath the burner assembly in line with the needle body  6 . In the figure the south pole S of the permanent magnet  13  is adjacent the north pole N of the body  6  which means, that the poles attract each other and the body  6  with the needle  7  is retracted in the chamber  3 , leaving the orifice  4  open. The separate permanent magnet  13  is rotable around the axis  14 , schematically indicated, and in this configuration, when the poles are attracted to each other, the permanent magnet  13  will maintain this position. The permanent magnet  13  is rotated 180° by means of e.g. a knob (not indicated) which means, that the south pole S of the magnet  13  now will be turned to the position with its south pole S adjacent the south pole S of the body  6 . This means that a repulse force is created between the magnet  13  and the body  6 , which inturn means that the body  6  is forced upwardly, whereby the needle  7  penetrates the orifice  4 . When the separate permanent magnet  13  is again rotated 180° the north pole N will now attrat the body  6  drawing the needle  7  out of the orifice  4 . This rotation of the magnet  13  back to the former position could be effected due to the repulsion forces between the south poles of the magnet  13  and the body  6  or could be effected by rotating the knob. 
     It could be said that it is often necessary to be able to draw the needle out of the orifice by force because of that the needle often get stuck in the orifice and the weight of the body with the needle will not be sufficient to bring the needle out of the orifice. Suitable permanent magnets are of type neodynium-magnets. The mounting and manoeuvering of the magnets is per se quite obvious and is not an essential part of the invention. 
     It should be understood that instead of using a slidable device  10 , a rotable device could be used provided with the magnets  8 , 9 . Further, of course the chamber  3  and body  6  could have forms differing from the cylindrical form, e.g. square or triangular form.