US1785160A - Fuel-feed control - Google Patents

Description

Dec. 16, 1930. B. VALJEAN FUEL FEED CONTROL Filed Sept. 16, 1929 l //ll///lI17/////I///I/lll// A Patented Dec. 16,1930 y UNITED TATES ATENT FFlcE :BENV VALJ'EAN, OF LANSING, MICHIGAN, .ASSIGNOR TO MOTOR WHEEL CORPORATION,

F LANSING, MICHIGAN, A CORPORATION 0F MICHIGAN FUEL-FEED CONTROL Application filed September 19, 1929. Serial No. 393,627.

There has developed a demand for factory produced and adjusted, fully automatic oil burning devices that will continuously function correctly without attention. There is also a demand that oil burning devices function at a higher point of efficiency. The main thing that `prevents obtaining the high eiliciencies vthat can be obtained in laboratory tests in combustion app-aratus is the inability to make a factory adjustment that will properly balance the air and fuel supply when the apparatus is installed in the field. If the fuel supply is too greatv there is not only waste but the deadly carbon monoxide gas is formed. 1f the fuel supply is deficient, there is low efficiency due to excess air. 1n these automatic devices there is also the chance for sev rions diiculty in case the pilot or igniting fire fails to -function. l

To overcome the above difficulties, to control the How of the fuel to a standard amount balanced with the standard air flow, and to secure a pilot flame which can be maintained at alow or economical point without danger ot expiring, constitute primary objects of the present invention.

ln order that the invention may be readily understood, a preferred embodiment of the 4invention is hereinafter described and illustrated in the accompanying drawings by way of example.

1n the drawings:

Fig.l 1 is a fragmentary view of` a heater and control mechanism, partly in elevation concave bottom 19 for the pool of fuel oil and a slight depression forming a pan 20 for holding the oil to maintain a pilot at that point. Both the pilot'tlame and the burner.

llame proper are supplied with oil through the pipe 21 leading from the main supply -pipe 22 by way of a float chamber interposed in the path of the fuel. A

The ioat mechanism comprises a casing 23 enclosing the chamber 24 the entry to which. from the pipe 22, is by way of an inlet port controlled by the point of a needle valve. The stem 25 of the needle valve has adjustably mounted thereon a collar 26 with which engages one end of a lever 27, the opposite end of the lever carrying a float member 28 which is buoyed up by the oil within the chamber so as to maintain a constant'leven therein. The outlet from the float chamber to the pipe 21 is governed by two valves having perpendicular stems 29 and 30. The valve 29 supplies oil for the burner flameproper while the Valve 30 supplies oil, in reduced amount, for the pilot flame. Both valves are normally held in open position by compression springs 31 and 32 respectively, while the valve 29 is provided with manually operable means 33 for closing the valve against the tension of the spring where no burner flame is required.

Disposed within the burner 17 directly above the location of the pilot at 20 is shown, by way of example only, a thermostat tube 34 containing a bimetallic bar 35, the elements of which have unequal coefcients of expansion. Under the heat of the pilot flame the bar 35 tends to bend upwardly and upon cooling to bend downwardly. A lever fulcrumed at 36 has a spring arm 37 the end of which adjacent the burner carries a set screw 38 which bearsr at its lower end upon the thermostatic bar 35 while the other arm 39 of the lever engages a collar 40 adjustably mounted upon the valve stern 30. A second lever fulcrumed at 41'carries at that end adjacent the burner a set screw 42, the lower end of which is in the path of the thermostatic bar 35. The other end of the lever engages loosely withinv a collar 43 adjustably carried by the valve stem 29.

The burner, in this illustrative embodiment,

is of the pre-mixing carburetor type and its. lunctioninan isthat set forth in my Patents Nos. 1,128,596, 1,512,869 and 1,639,202. Gren-y erally speaking, that portion of the burner below the neck is a pre-mixing chamber wherein insuflicient to maintain complete combustion.

During the initial stages before the burner becomes fully heated there is some flame within the pre-mixing chamber but complete combustion takes place under normal operation in and abovethe neck 16 above the gap 44 through which anadditional supply of air enters suflicient to effect complete combustion. As the burner becomes more heated, substantially all of the flame leaves the pre-mixing chamber 17 and combustion is confined to a location above the gap 44.

Assuming a pilot flame to be burning at 20, the thermostatic bar 35 acted upon by the flame will control the pilot valve 30 to maintain a temperature in the pilot flame for which the set screw 38 is adjusted. If, by reason of decrease in heat or impurity in the oil or obstruction of the port controlled by the valve 30, the pilot flame loses its intensity, the action of the thermostatic bar 35 will open the valve 30 to a larger extent whereas, if the pilot flame becomes too intense, the valve will be partially closed by the reverse bending of the thermostatic vbar'35.

In practice, a postion can be located generally near the base of a flame where the temperature variation is unaffected by the amount of heat being absorbed from the flame, as for instance. the water in a boiler. The absorption of heat results in a lowering of the temperature at the tip of the flame and beyond, but does not materially aflect the temperature at the inception point of the flame or its base. The temperature at the base of the flame varies with the amount of fuel consumed. Since, in a burner of the type herein set forth, the base of the flame rises as the intensity of the fire increases, and as the thermostatic tube 34 with its bar 35 is located below the base of the flame when under full operation, it will be affected by a decrease in temperature instead of`a rise as the flow of oil increases. If it be desired to maintain the feed of fuel at a stage to maintain'the base of the flame under normal operation at or above the gap 44, it is possible to utilizethis change from a rising to decreasing temperature at such critical stage as a medium for reducing the oil flow and thus preventing a further lifting of the base of the flame by a supply of oil 1n excess.

At the intermediate stage, after the lighting of the oil in the pool of the burner from the pilot, combustion will take place within the burner below the gap. The heat of this flame will first cause the thermostatic bar 35 to move upwardly sufficient to close off the pilot and, as the bar moves further upward under the increase of temperature, it will enage directly the set screw 42, thereby opening the valve 29 beyond the point for the normal feed of fuel. However, as combustion progresses and the base of the flame rises to and above the gap 44 there will be a resulting lowering of the temperature within the premixing chamber about the thermostatic tube 34, and the bar 35 will again move downward away from the set screw 42, thus permitting the valve 29 to `resume its normal flow of oil to maintain the flame in its elevated position in the neck of the burner. If, by reason of sediment at the port controlled by the valve through the valve 29 is cut olf entirely by the hand wheel 33 the ame Within the burner will drop and gradually disappear as the pool of oil at 19 is consumed, leaving only a pilot flame at 20. To provide for this there is also a certain degree of resiliency in the lever which is fulcrumed at 41 an'd carries the set screw 42.

I claim:

1. The combination with a fluid fuel burner of the carburetor type and a fuel supply passage, of means for automatically controlling the supply of fuel to the pilot and to the burner, said control meansfcomprising a thermostatic device disposed within the carbureting chamber of the burner above the pilot and below the normal flame area, independently acting valves in the fuel supply passage, a connection between each of the valves and the thermostat whereby to o en and close the pilot valve to a greater or ess extent to Vmaintain a. uniform degree of heat at the pilot in the absence of flame within the burner proper, to increase the flow of fuel to the burner in the intermediate stage when there is flame in the burner proper and again to decrease the flow of fuel to the burner when the base of the flame rises above the burner proper as in normal operation.

2. The combination with a fluid fuel burner of the carburetor type and a fuel supply passage, of unitary means for automatically controlling the supply of fuel to the pilot and to the burner, said control means comprising a thermostatic device including a bimetallic bar disposed within the carburetin chamber of the 'burner above the pilot andelow the normal flame area, independently acting needle valves arranged in tandem in the fuel supply passage, a lever connection between each of the valves and the thermostat where by to open and close the -ilot valve to a greater or less extend to'mamtain a uniform degree of heat at the pilot in the absence of flame within the burner proper, to increase the ow of fuel to the burner in the intermediate stage when there is flame in the burner proper and again to decrease the ow of fuel to the burner when the base of the flame rises above the burner proper as in normal operation.

n 3. The combination with a fluid fuel burner of the carburetor type and a fuel supply passage, of unitary means for automatically controlling the supply of fuel to the pilot and to the burner, said control means comprising extent as combustion in' the burner reachesl 'scribed my name.

a thermostatic device including a bimetallic bar dis osed within the carburetin chamber of the urner above the pilot andelow the normal flame area, independently acting needie valves arranged intandem in the fuel supply passage, one controlling the flow of oil to the pilot and the other controlling the flow of oil to the burner proper, a lever suitably fulcrumed and engaging at one point with the pilot valve and at-another point disposed in the path of the thermostatic bar, a second lever suitably fulcrumed and engaging at one point the burner valve. and at another point disposed in the path of the thermostatic bar, whereby the pilot valve will be l opened`to a reater or less extent under the iniiuence of c an e of heat ofthe pilot flame to maintain uni ormity andthe burner valve will be opened to a greater extent during the incipient stages' of combustionand to a less normal. y In testimony whereof I have hereunto sub- .,BEN VALJEA'N.

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