Bear with me on this, some preparatory notes while I’m fettling the stove in question, from French manufacturer Veuve F. Vulin (‘widow of F. Vulin’ - she took over her late husband’s business). The stove is a Superforézien No.1 of 1928. A single burner kerosene stove, the No.2 was a twin burner stove on similar lines, both featuring in this catalogue. A contemporary patent describes the ‘no stuffing box’ concept. Translation: Adjustment device for heating appliances using pressurised liquid fuel. In most known heating appliances using pressurised liquid fuel, such as kerosene, gasoline, alcohol, etc., flame adjustment is achieved by varying the air pressure in the reservoir. To decrease the flame intensity, the air release screw or fuel filler cap is opened briefly; to increase the intensity, air is introduced by means of a pump, whether independent of the appliance or not. Alternatively, a simpler method of adjustment has been sought by maintaining constant pressure in the reservoir and modifying the effective cross-section of the jet nipple. This is achieved by partially blocking the het nipple with a needle valve operated externally via a system of metal rods. This adjustment device has the disadvantage of requiring a stuffing box between the operating rod, which communicates with the outside, and its housing, which communicates with the pressurised liquid. However, the stuffing box wears out quickly and must be replaced frequently to ensure the appliance continues to function properly. The present invention relates to adjusting the flame of a heating appliance of the type described above by partially blocking the jet nipple using a needle valve operated externally, without the need for any seal. According to the invention, the needle valve's movements are due to the deformation of a thin tube. One end of this tube is completely sealed and immersed in the liquid, guiding the needle valve. The inside of this tube contains a rigid control rod of suitable shape. The movement of this rod determines the tube's deformation and is controlled by a hand-wheel. The accompanying drawing illustrates, by way of example, an embodiment of the invention. Fig. 1 shows the arrangement in cross-section. According to the figure, on the supply tube a, coming from the tank, the end of a metal tube c is brazed in section b, the other end of which is sealed by a plug d with an orifice e. Inside tube c, a second tube f, made of thin metal or plastic, is perfectly sealed at its end g, connected to the needle valve i, and is brazed or welded at j to the plug d. The control rod h within flexible tube f is slightly bent in its length, which when the hand-wheel l is rotated flexes tube f and creates vertical motion alternately up and down to the needle valve i. The fuel that enters tube c from supply tube a therefore has absolutely no contact with the outside air and pressure is maintained in the fuel tank. Here’s the catalogue illustration of the mechanism. Fettling is nearly complete and was one of my tougher projects! The pump tube was in theory removable to gain access to the non-return valve, but the hexagon nut securing it to the threaded boss soldered to the tank was immovable, threads seized solid. Applying anything but moderate torque to the nut was impossible without damaging the brass fuel tank. A lengthy soak in an acetone/atf mixture had no effect and nor did a dunk in boiling water. I’d to de-solder the pump tube yet the tank boss/hexagon nut lump, now slid off the pump tube still wouldn’t part company. I resolved to fabricate a ‘dummy’ hexagon nut to silbraze to the pump tube, then it would be soft-soldered to the tank. This necessitated replacing the existing NRV and pump end cap with a conventional end cap and NRV accessible with a NRV tool via the pump tube. The large, heavy burner and weighty ‘no stuffing box’ mechanism housing had taken its toll on the burner supply pipe-to-tank solder joint and had broken free. I wasn’t content to simply re-solder the original joint and silbrazed a reinforcing collar to the pipe to increase the surface area to be soldered to the tank, a much more robust arrangement. No silent burner inner cap, so I’d to make one. So far so good, some cosmetic work to be done then I’ll post details in the Stove Reference Gallery. Firing up the stove should be fun, knowing that silent burners can be fickle, so an unconventional one like this may well misbehave! We’ll see. John
This is a very interesting design for an eccentric mechanism. The cross-sectional diagram is very helpful in understanding how it all works.
