GB1585991A - Oil burner - Google Patents

Abstract

The shaft (2) of a motor (1) of a burner drives the fan (3) and the oil pump (4), which convey air and oil to the mixer (5). The shaft (2) has a thread (7), which engages with an internal thread of a hub (9). Arranged on the hub (9) is a disk (8). As a result of the influence of the rotating and stopping of the shaft (2), the hub (9) and the disk (8) are moved axially to and fro, closing and opening the air inlet channel (6). The device consequently prevents an undesired cooling of the combustion chamber of the boiler by cool air currents, which flow in through the air inlet channel (6). <IMAGE>

Description

(54) AN OIL BURNER (71) We, NORTTI-TUOTE OY, of Vattuniemenkatu 10 00210, Helsinki 21, Finland, a Finnish Company, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to an oil burner having means for automatically closing and opening the air intake duct of the burner as the burner stops and starts, said burner comprising a motor whence projects a shaft passing through the air intake duct, this shaft driving a fan and an oil pump, which feed air and oil into a mixer.

The problem encountered in oil burners of prior art is that the air duct remains open when the burner stops, whereby considerable air quantities pass through the firebox of the boiler, causing it to cool and resulting in appreciable loss of energy. The longer the non-operating times of the burner in proportion to the running periods, the greater will be the energy losses hereby incurred. If it were possible altogether to inhibit the air flow, this would mean in the heating of one-family houses and of small blocks of flats, in, by way of example, Finnish conditions and in the wintertime, a 12% oil saving and in the summertime a saving of 27%.

Attempts have been made to prevent this cooling air flow e.g. by means of a damper mounted in the chimney and operated by a damper control motor. However, arrangements of this kind involve considerable detriments, one of them the risk that the damper fails to open or that it fails to close tightly, owing to soot and other dirt. In certain cases it has also happened that the pressure caused by heat rose to such high values that the ducts burst open explosively.

The object of the present invention is to eliminate the problem without any dampers mounted in the stack and with minimal cost so that closing and opening of the air duct take place automatically without requiring any extra energy or control.

In accordance with the present invention there is provided an oil burner comprising an air intake duct, a motor from which projects a shaft passing through the air intake duct, a fan and an oil pump drivable by the shaft to feed air and oil respectively to a mixer, and means for automatically closing and opening the air intake duct as the burner stops and starts, said means comprising a plate which is mounted on the shaft for movement in an axial direction between a first position in which it closes the air duct and a second position in which it opens the air duct, at least movement in that axial direction from said first to said second position being effected by rotation of the shaft.

Advantageously, the shaft is provided with a thread, on which an internal thread of a hub of the plate engages to afford free rotation. Thus as the motor and shaft stop, the plate will continue to rotate, whereby the thread will cause the plate to move in an axial direction until it abuts on the walls of the air duct, thereby closing the air duct.

Similarly, when the motor begins to rotate the plate will not immediately rotate in synchronism with the motor due to the inertia of the plate and, therefore, relative rotation will occur between the shaft and the plate resulting in the plate moving into a position in which it opens the duct.

The invention will now be more particularly described with reference to the attached drawing, which is a schematic sectional view of one embodiment of an oil burner according to the invention.

A motor 1 has a shaft 2 which drives a fan 3 and an oil pump 4, which feed air and oil respectively into a mixer 5. The reference numeral 6 indicates an air duct, tapered conically or stepwise and ending at a cavity formed within the blades of the fan 3.

The shaft 2 is provided with a thread 7, and a circular plate 8 is arranged to be freely rotatable about the threaded part 7, on which it is carried by a hub 9 having an inner thread mating with the first-mentioned thread. When the motor 1 stops the plate 8 together with its hub 9 will continue to rotate, owing to the kinetic energy that is stored in it. The plate 8 will then move by effect of the thread 7 from right to left as viewed in the drawing and it will close the air duct 6. When the motor 1 starts to rotate, the plate 8 does not at once reach the same speed, whereby owing to the rotation of the shaft 2 and plate 8 relative to each other the plate 8 moves from left to right as viewed in the drawing, that is into the position shown, thereby opening the air duct 6.It is possible to mount in the thread 7 an appropriate stop pin 10 with such shaping of the thread in the hub 9 that it will catch on this pin, whereby there will be no jamming and, in contrast. the plate 8 remains freely and easily rotatable.

The embodiment above described is not the only way in which the rotation of the shaft 2 mav be utilized to shift the position of the plate 8. A well-usable embodiment is that in which the shaft 2 carries one or several substantially axial slide grooves or ridges which are engaged by a corresponding sliding ridge or groove on the hub 9 of the plate 8 and the plate 8 is provided with vanes which as the plate rotates will push it axially from left to right to open the duct 6.

For returning the plate 8 to the position in which it closes the duct 6. one may provide for instance a comparatively sensitive spring. which is barelv able to return the plate 8 into the position in which it closes the duct 6. In the embodiment shown in the drawing. too. vanes on the plate 8 may be employed to enhance the shifting. although it has been found practical trials that the inertia force is enough to shift the plate 8.

The spring returning the plate 8 is not absolutely necessarv. because the air flow which one desires to inhibit bv closing the air duct is strong enough to return the plate 8. Also centrifugal devices mav be utilized to cause the movement of the plate 8 required to open the intake during rotation of the shaft 2. whereby a spring. acting against the centrifugal device. may be used to close the intake when the rotation stops.

WHAT WE CLAIM IS: 1. An oil burner comprising an air intake duct. a motor from which projects a shaft passing through the air intake duct. a fan and an oil pump drivable by the shaft to feed air and oil respectively to a mixer. and means for automatically closing and opening the air intake duct as the burner stops and starts. said means comprising a plate which is mounted on the shaft for movement in an axial direction between a first position in which it closes the air duct and a second position in which it opens the air duct, at least movement in that axial direction from said first to said second position being effected by rotation of the shaft.

2. An oil burner as claimed in claim 1, wherein the shaft is provided with a thread, on which an internal thread of a hub of the plate engages to afford free rotation.

3. An oil burner as claimed in claim 1, wherein the shaft has one or more substantially axial sliding grooves or ridges, in which a corresponding sliding ridge or groove on a hub of the plate engages, the plate being provided with vanes or a centrifugal device which, in use, as the plate rotates move the plate in an axial direction against the force of spring means.

4. An oil burner as claimed in any one of the preceding claims wherein the plate abuts, in use. in its closed position on the wall of the air duct which is of stepwise or conically tapering form.

5. An oil burner substantially as herein described with reference to and as shown in the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. formed within the blades of the fan 3. The shaft 2 is provided with a thread 7, and a circular plate 8 is arranged to be freely rotatable about the threaded part 7, on which it is carried by a hub 9 having an inner thread mating with the first-mentioned thread. When the motor 1 stops the plate 8 together with its hub 9 will continue to rotate, owing to the kinetic energy that is stored in it. The plate 8 will then move by effect of the thread 7 from right to left as viewed in the drawing and it will close the air duct 6. When the motor 1 starts to rotate, the plate 8 does not at once reach the same speed, whereby owing to the rotation of the shaft 2 and plate 8 relative to each other the plate 8 moves from left to right as viewed in the drawing, that is into the position shown, thereby opening the air duct 6.It is possible to mount in the thread 7 an appropriate stop pin 10 with such shaping of the thread in the hub 9 that it will catch on this pin, whereby there will be no jamming and, in contrast. the plate 8 remains freely and easily rotatable. The embodiment above described is not the only way in which the rotation of the shaft 2 mav be utilized to shift the position of the plate 8. A well-usable embodiment is that in which the shaft 2 carries one or several substantially axial slide grooves or ridges which are engaged by a corresponding sliding ridge or groove on the hub 9 of the plate 8 and the plate 8 is provided with vanes which as the plate rotates will push it axially from left to right to open the duct 6. For returning the plate 8 to the position in which it closes the duct 6. one may provide for instance a comparatively sensitive spring. which is barelv able to return the plate 8 into the position in which it closes the duct 6. In the embodiment shown in the drawing. too. vanes on the plate 8 may be employed to enhance the shifting. although it has been found practical trials that the inertia force is enough to shift the plate 8. The spring returning the plate 8 is not absolutely necessarv. because the air flow which one desires to inhibit bv closing the air duct is strong enough to return the plate 8. Also centrifugal devices mav be utilized to cause the movement of the plate 8 required to open the intake during rotation of the shaft 2. whereby a spring. acting against the centrifugal device. may be used to close the intake when the rotation stops. WHAT WE CLAIM IS:

1. An oil burner comprising an air intake duct. a motor from which projects a shaft passing through the air intake duct. a fan and an oil pump drivable by the shaft to feed air and oil respectively to a mixer. and means for automatically closing and opening the air intake duct as the burner stops and starts. said means comprising a plate which is mounted on the shaft for movement in an axial direction between a first position in which it closes the air duct and a second position in which it opens the air duct, at least movement in that axial direction from said first to said second position being effected by rotation of the shaft.

2. An oil burner as claimed in claim 1, wherein the shaft is provided with a thread, on which an internal thread of a hub of the plate engages to afford free rotation.

3. An oil burner as claimed in claim 1, wherein the shaft has one or more substantially axial sliding grooves or ridges, in which a corresponding sliding ridge or groove on a hub of the plate engages, the plate being provided with vanes or a centrifugal device which, in use, as the plate rotates move the plate in an axial direction against the force of spring means.

4. An oil burner as claimed in any one of the preceding claims wherein the plate abuts, in use. in its closed position on the wall of the air duct which is of stepwise or conically tapering form.

5. An oil burner substantially as herein described with reference to and as shown in the accompanying drawing.