US2020735A - Thermal electric control - Google Patents

Description

Nov. 12, 1935. H, w PARTLQW 2,020,735

THERMAL ELECTRIC CONTROL 'Filed April 5, 1935 2 Sheets-Sheet 1 Zinnenfor M 7% 0mm; 82 74 MW.

attorney.

Nov. 12, 1935.

H. W. PARTLOW THERMAL ELECTRIC CONTROL Filed April 3, 1935 2 Sheets-Sheet 2 ISnnentor Patented Nev. 12, 1935 UNETED STATES PATENT OFFICE Application April 3, 1935, Serial No. 14,493

2 Claims.

This invention relates to automatic control for gas burners employed in connection with industrial ovens, and the like, and has especial reference to a novel pilot burner mechanism whereby the supply of gas to the oven burners,

as well as to the pilot burner, is controlled thermally and electrically.

The object of the invention is to provide .a main valve to supply gas to the burners of an oven,

or the like, and a solenoid or other electric means to control said valve. A further object is to provide an auxiliary valve that independently supplies gas to the pilot burner, and a thermostat including an expansive fluid adapted when heated by the pilot burner to inaugurate the automatic control of said main valve. A further object is to provide simple means for manually opening the auxiliary valve and at .the same time juxtaposing terminals of an electric circuit which effects the initial opening of the main valve to feed the gas to the oven burners when the thermostat attains its maximum stage and completes said circuit; the auxiliary and main valves being closed automatically by the separation of said terminals following the extinguishment of the pilot burner and the consequent contraction of said fluid. And a further object is to generally improve and simplify as well as to r nder more automatic and positive the construction and operation of thermally controlled industrial ovens, or other gas burning heaters, and to substitute electricity for certain manually and mechanically operated devices, which heretofore have not been found entirely efficient, positive and safe.

I attain these objects by the means set forth in the detailed description which follows, and as illustrated by the accompanying drawings, in which- Figure 1 is a top plan view of the pilot burner mechanism showing the said burner in relation to a pair of oven burners; also showing the main gas valve and a solenoid for controlling said valve. Fig. 2 is a front side elevation of the same. Fig. 3 is a vertical longitudinal section taken substantially on line 33 of Fig. 1, showing the manually operable parts, also showing the mechanical parts that are operated by the variations of the thermostat; also showing means for making the electric circuit that initially opens the main gas valve. Fig. i is a broken View similar to Fig. 3, showing the electric contact arms engaged for completing the circuit that actuates the solenoid for opening the main valve. Figs. 5 and 6 are respectively a top and a side view of the manual- 1y controlled contact lever. Figs. '7 and 8 are respectively a side and a front elevation of the contact arm operated by the thermostat. And Fig. 9 is a central vertical section of the solenoid and main valve, taken on line 99 of Fig. 1.

Referring to Figs. 1 and 2 of the drawings, 2 5 represents a plurality of gas-burners adapted to heat an oven or other gas-burning plant, in which the burners are generally arranged in pairs and receive the gas from a main conduit, as A. The fuel-gas is preferably dispensed by a self-closing 10 valve, as 3, which is disposed in the main A, and which may be opened by a solenoid, or other source of power, as 4, which is preferably operated by electric current derived from mains, as x and m. 15

The supply of gas for the burners 2 and the lighting thereof are controlled by a novel mechanism that includes a pilot burner P, and a selfclosing auxiliary valve P, which is supplied with gas independently of the valve 3, by a pipe P" 20 that taps the main A. The valve P is Supported by a casing 5 having an opening 5' for the insertion of a hub 50!. of the valve body, the hub being bored to receive the valve stem 5b, whose free end projects into the casing 5. Stem 5b 25 is normally held in the extended position of Fig. 3, by a spring 50 that serves to automatically close valve P, in case the pilot light is extinguished. Within the casing 5 is disposed a rockable lever or arm 6, which is rigid to a shaftfi that pro- 30 jects through the rear wall of the casing and is fitted with a hand-lever fia, by which the arm .6 may be rocked manually in a vertical plane, as shown in Figs. 2 and 3. The arm 6 is inconstant engagement with the free end of stem 5b, so that 35 when said arm is swung downwardly by the manipulation of handle 6a, the valve P opens, as shown in Fig. 3. The gas then flows via a pipe lid to a distributing member 5e, and thence via a pipe 5 to the pilot burner P, whose primary 40 ofiice is to heat a thermostat T which controls the valve 3, and light the oven burners, as may be understood by consulting Figs. 1, 2, 3 and 4. Thepipe 5, is fitted with a cock 5.1:, by which the gas to the burner P may be turned on and oh 45 manually, to start or terminate a heating interval. The arm 6 is formed adjacent its free end with a lateral tooth, as 6b, shown in Figs. 3, 4, 5 and 8, which, when said arm is depressed, as in Fig. 3, engages a hook I carried by an L-shaped member I, which is pivoted at 1a to an upright oscillatable lever,8, the latter being pivoted at Sea to the rear wallof the casing, and being normally held inoperative by a spring 831:, shown in Figs. 3 and 4.

This disposes the hook 1 directly in the path 55 of the tooth 5b, and the latter rocks the member i on its pivot la away from the lever 8 sufiiciently to mlow tooth ill) to snap beneath said hook, as shown in Fig. 3. This locks the arm 6 temporarily in its primary operated position, beyond further control of the omrator, and not liable to be released from hook 1 until the next regular step in the preliminary cycle of operation is completed through the subsequent heating of the thermostat.

The thermostat T comprises a hollow body T closed at one end by an axially bored cap or head 15, and in which is disposed a reciprocable plunger 9, one end of which is normally held in engagement with a diaphragm 9' by a spring 9a., the opposite end of the plunger extending into member 5e, where it engages a similar axially aligning bolt 8b, whose free end 90 is preferably in constant engagement with the lever 8 (see Figs. 3 and 4). The bore of the head t communicates at one end with a chamber 15, its opposite end connecting with a tube 903, which is formed with a bulb tie, that extends into the oven and is preferably charged with mercury or other expansible element; the bulb 9e being disposed directly over the pilot flame, which heats and expands the mercury for controlling the oscillation of lever B, as may be understood by consulting Figs. 3 and 4. During the initial heating of the mercury, lever 6 is held by the hook I in the full line position of Fig. 3.

The levers B and 8 are fitted respectively with electric terminals (Sc-82 that are insulated, as at a, from said levers, and being held in place by fasteners ,f. The corresponding ends of these terminals comprise contact teeth 6d8c which the burners 2 for heating the oven.

To safeguard against the opening of the main valve 3 before the pilot'mechanism is ready to effect the perfect control of a heating plant, the

lever 6 is primarily detained by the hook I during an interval ranging from three to six minutes-the time ordinarily required to, properly heat the thermostat. To this end the tooth 6b is preferably made slightly broader than the normalgap between the hook I and terminal 80,

which enables the lever 8 to be moved by the expanding mercury until the tooth 8c slightly overlaps the tip 6d of terminal 50. This precautionary arrangement is rendered possible of achievement by the fact that the tip 641' of terminal 6c is normally disposed in a slightly lower plane than tip 80 of terminal 8b, which allows the necessary freedom and time for lever 8 to lever 3, although the hook portion 1 of said member I may rock on its pivot 1a away from lever B for the purpose of effecting the temporary interlocking of tooth 6b and hook I, as explained.

The temporary latching of the lever B to the hook 1 takes the control of the pilot mechanism out of the hands of the operator and preferably delays the opening of the main valve 3 until the thermostat T becomes heated to the extent that it shifts the lever 6 from the hook I and efiects its interlocking with the safety latch 81), and completes the electric circuit to open the main valve 3. This initiates the electric and automatic control of the heating plant which continues as 10 long as the pilot burner remains lighted.

When the pilot burner becomes extinguished from any cause, the mercury of the thermostat cools. and relaxes the pressure that holds the lever 8 in the operative position of Fig. 4, and allows the spring 8x to separate the terminals tic-81) by restoring the levers 6 and 8 to their inoperative positions of Fig. 3. The book loannot reengage the tooth 6b so the lever B is pushed up by the stem 5b and spring 50 and assumes the position shown by the dotted lines in Fig. 3, which allows the valves 3P to close automatically.

Having thus described my invention, What I claim,.isl. A thermal-electric control for self-closing gas valves including a main burner having a valve for controlling the gas supply thereto, electric means for opening said valve, a pilot burner disposed in igniting relation to the main burner, a self-closing valve for controlling the gas supply to the pilot burner, a thermostat responsive to the heat from the pilot burner, a manually operable lever in constant engagement with the pilot burner valve to open same, an oscillatory $5 lever having a yieldable hook member engageable with said first lever to temporarily hold the latter and thereby the pilot burner valve in open position, said levers having normally separated electric contacts in circuit with the means for opening the valve of the main burner, means operable by the thermostat to move the oscillatory lever to disengage said hook from the first lever and to then move same to effect engagement of said contacts to complete the circuit and open 4 the main valve, and spring means for operating the oscillatory lever to separate the terminals and open the circuit upon extinguishing of the pilot burner.

2. A thermal-electric control for self-closing gas valves including a main burner having a valve for controlling the gas supply thereto, electric means for opening said valve, a pilot burner disposed in igniting relation to the main burner,

a self-closing valve for controlling the gas supply to the pilot burner, a thermostat responsive to the heat from the pilot burner, a pair of independent rockable levers having electric contacts for engagement with each other and being in circuit with the means for opening the valve of $6 the main burner, means to operate one of the levers to effect opening of the pilot burner valve, means operable by the other lever to temporarily hold said first lever stationary while the thermostat is being heated, means operable by the 6 thermostat to actuate said other lever to first release and then look the first lever in a position where said contacts engage and thereby open the main valve, and means operable upon extinguishment of the pilot burner to effect separa- 6 tion of the contacts whereby to close the main and pilot burner valves.

HOWARD W. PARTLOW.

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