US2972354A

US2972354A - mccarty

Info

Publication number: US2972354A
Authority: US
Publication date: 1961-02-21
Anticipated expiration: 1978-02-21

Description

Feb. 2l, 1961 Filed NOV. 25, 1956 L. V. MCCARTY SAFE LIGHTING MECHANISM 2 Sheets-Sheet 1 Lounnes V. MnCARTY Feb. 21, 1961 L. v. MccARTY 2,972,354

SAFE LIGHTING MEQHANISM Filed Nov. 25, 195e 2 sheets-sheet 2 Lounoas V. Mc C M11-Y United States Patentl` O trols Company of America, SchllerPark, Ill., a corporation of Delaware Filed Nov. 23, 1956, Ser. No. 623,942

25 Claims. (Cl. 137-66) This invention relates to a safe lightingmechanism for gas burners having a main burner and a pilot burner. The

apparatus provides 100% safe shut olf in the event the pilot burner is extinguished. v

The safe lighting and fail safe mechanisms provided in l.the art have generally contemplated a safety valve interlocked with a valve in the main burner supply line so the safety valve can be reset to the safety position only when tne flow to the main burner is shut off. These interlocking arrangements are subject to various objections and the present invention provides a fresh appro-ach to the problem and eliminates the need for the usual interlocked shut olf i valve in the main burner supply. The present invention contemplates temporarily opening a bypass to the pilot burner in order to ignite the pilot burner kand heat the thermocouple of the sa-fety valve mechanism. When the actual resetting operation is carried out, the bypass iiow to the pilot burner is shut off and the safety valve is moved to its electromagnet in the usual thermocouple arrange' ment and allows full iiow to the main and pilot burners. The mechanism is operative to hold the armature carrying the safety valve against the electromagnet for only a very short period of time and unless the electromagnet is energized by the thermocouple the safety valve will be free to close and thus shut offflow to both the main and pilot burners. It will be seen that'during the actual resetting operation there is flow both to the main burner and to the pilot burner past the safety valve. The amount of gas reaching the main burner in the short period of time is negligible and is of no consequence from the safety stand'- point. Therefore, the present mechanism is totally safe even though it does permit llow to the main burner during the 4actual resetting operation. The bypass to the pilot burner is only operative temporarily and infnormal operation the safety valve controls ow to both the main and pilot burners. Thus, extinction ofthe pilot burner will result in closure of the safety valve to shut olf both burners. by the resetting operation and can not lead to an unsafe condition.

The principal object of this invention is to provide a Fig. 3 is similar to Fig. 1 but shows the actual resetting operation; and

Fig. 4 shows the safety valve reset or held in the safety position and permitting ow to both the mainand pilot burners with the bypass to the pilot burner shut o.

Referring now to the drawings in detail, valve body 10 includes two parts 12 vand 14 with gasket 16 between the two body parts. The split construction is employed to facilitate assembly of the parts. The body is provided with inlet 18 into which supply conduit 20 is threaded and has outlet 22 into which conduit 24 leading to the main burner is threaded. The body also has outlet 26 in which conduit 23 is threaded to supply the pilot burner. It will be appreciated that conduit 24 leading to the main burner may have athermostatically controlled solenoid valve or the like in the line to thermostatically regulate the heater. Such apparatus, however, forms no part of this invention.

Inlet 18 leads to chamber 30 in which the usual thermoelectric safety pilot mechanism (commonly called a hood assembly) is mounted. This includes an'electromagnet mounted within casing 32 and 'safety valve 34 biased towards seat'36 by spring 38 and having an varmature at the lower end of its stem 40 adapted to be pushed against the electromagnet and retained thereby ifthe usual thermocouple (not shown) is energized by the heat of the pilot burner flame. The hood assembly is mounted in the body by means of fitting 42. As shown in Fig. l, spring 38 is holding safety valve 34 against seat 36 to shut off flow to both the main and the pilot burners.

The safety valve is adapted to be moved open to reset the armature to the electromagnet by actuation of a resetting means 43. The structure and operation of the resetting means is as follows: As may be seen in Figs. l and 4, pin 46 carried by cup 48 normally cannot reach valve nut 44 and thus is unable to actuate the valve to its open position o-r to hold the valve in its open position. Cup 48 is normally held up against the underside of body part 14 by spring 50 compressed between the inwardly turned flange 52 of the cup and the upper surface of piston 54 carried on the lower end of stem 56. Spring 58 compressed between the valve bodyand the piston 54 holds the stem in its lowermost position as shown in Figs.

The temporary bypass is rendered inoperative safe lighting mechanism for gas burners having a main and pilot burner and additionally providing 100% safe shut olf in the event thefpilot burner is extinguished. y

Another object of this invention is to safely permit ow Ato both the main and the pilot burner during the resetting operation of the safety valve mechanism.

Other objects and advantages will be` pointed out in, or be apparent from the specification and claims, as will obvious modifications of the embodiment shown in the draw.- in-gs, in which:

Fig.. l is 'a somewhat schematic representation of the present invention in vertical section and showing theparts in the 100% safe shut off position;

Fig. 2 is'similar to Fig. l but shows thepilot burner bypass open to permit lighting the pilot burner prior to resetting the safety mechanism;

1, 3 and 4. While the stem is held in its lowermost'position by spring 58 spring 50 acts to raise the cup to its uppermost position, as in Figs. l and 4. Piston 54 lits snugly within the cup to act as a dash pot. The upper end of the cup may be slotted or punched to provide a hole, such as at 60, to permit gas to flow from chamber 62 into the space inside the cup and between the reduced diameter portion 64 of stem 56 and passage 66 to pilot burner outlet 26.

In order to light the pilot burner it is necessary to lift knob 68 on the upper end or bypass valve 69 of stem 56 to move the reduced diameter portion 64 of the stem upwards until it cooperates with passage 70 to permit flow from inlet 18 through

passages

72, 70 and 66'and into the pilot burner outlet 26 (Fig. 2). When this is done the lower portion 74 of the stem 56 moves into passage 66 to prevent flow to the main burner constituting a third valve in the iiow path between the

bypass passages

72, 70 and the main burner. lThus, the fuel supply is limited toflow to the pilot burner and the pilot burner may be lit. When the resetting means 43 is lifted as in Fig. 2, springs 50 and `58 are compressed as shown in Fig. 2. While the stem is hole Y60 and past piston 54 to more or less chargev the dash pot. A bleed hole 61 in the bottom of cup48 may be provided, if desired,.to insure proper action ofthe dash pot,

When the resetting means"43`is released,'spring58 will drive stem 56 downwardly and since air is trapped between the cup and the piston the cup will be carried downwardly with stem 56 and effectively add sufficient length to the resetting means to push the safety valve open as in Fig. 3 and move the armature againstthe electromagnet for retention thereby if the pilot burner has heated the thermocouple suiciently. It should be noted that the necked down portion 65, of stem 56 is of s uf cient length to temporarily overlap passage 70 and the space below passage 66 to permit smooth transition from the bypass flow tothe normal pilot iiow and have no interruption of gas flow to the pilot burner. After the spring S moves the resetting means 43 down to the limit determined by engagement of head 68 with the valve body as shown in Fig. 3, the bypass ilow is completely shut olf and the cup is held by the dash pot action in position Where the pin 4d can temporarily hold the safety valve open. As the air or gas bleeds out of the cup the spring 50 will move the cup inwardly until it again seats against the underside of valve body part 14 to thereby effectively shorten the length of the resetting means. This can be designed to take approximately three or four seconds. If the thermocouple has been properly energized by the pilot burner the safety valve 34 will be held open as in Fig. 4 and flow will be established to both the main .burner and to the pilot burner. Since the pilot burner bypass is closed off by the stem 56, extinction of the pilot burner will de-energize the electromagnet holding the safety valve open and permit the spring 3S to move the safety Valve to seat 36 to shut off ow to both burners and thus achieve 100% safe shut off.

Since the main burner flow is permitted only three or four seconds during the resetting operation there is no danger even though ilow to the burner is not prevented during the resetting operation. The dash pot arrangement shown represents a convenient method for achieving the temporary elongation of the resetting means but it will be appreciated that mechanical trigger mechanisms could also be used. For this reason, the present invention is not to be limited to a dash pot action. Other changes in the structure will occur to those skilled in the art and the scope of this invention is, therefore, to be limited only by the scope of the claims and not by the disclosure in the drawings and this description.'

l claim: A

1. A safety valve arrangement for fuel burners comprising, a main burner conduit, a pilot burner conduit and a supply conduit supplying fuel to the main burner conduit and to the pilot burner conduit, valve means in said supply conduit for shutting off ow to both burner conduits, means biasing the valve means closed, energizable means operable to hold the valve means open in response to a control condition, the energizable means being inoperative to open the valve and requiring the valve to be reset after valve closure, a bypass conduit for delivering fuel to the pilot burner conduit from the supply conduit upstream of the valve means, a valve in the bypass conduit, means for opening the bypass valve to supply fuel to the pilot burner conduit, and resetting means opreative to open the valve means for a short period of time only and the valve means thereafter closing if the energizable means is not energized.

2. A safety valve arrangement according to claim 1 in which the resetting means is biased to reset the valve means to the energizable means.

3. A safety valve arrangement according to claim l in which the bypass valve and resetting mean are connected so that said bypass valve must be opened before the reset ting means can be operated.

4. A safety valve arrangement according to claim 3 in which operation of the resetting means is operative to close the bypass valve so closure of the valve means shuts olf all ow to both burner conduits.

5. A safety valve arrangement according to .claim 4 in esY which the resettiing means includes means requiring cocking before the resetting ymeans is operative to act on the valve means to open the valve means.

6. A safety valve arrangement according to claim 5 in which the resetting means and the bypass valve have a `common actuator and movement of the actuator to open the bypass valve also acts to `cock the resetting means.

7. A safety valve arrangement according to claim 6 in which the means requiring cocking renders the resetting means operative `only for a predetermined period ottime after the resetting means moves to open the valve means.

8. A safety valve arrangement according to claim 7 in which said actuator is biased in the direction to close the bypass valve and to move the resetting means in the resetting direction.

9. A safety valve arrangement according to claim 8 in which the resetting means includes a stem of insufficient length to Vreset the valve means., and the .means requiring Cooking temporarily adds ouleient length to the stom to reset the valve means.. Y

10 A safety valve arrangement aooordios to elaim 9 in which the means .requiring seeking inolodes a dash pot- 11- .A safety valvearrensement according to olaim 1 in which said supply conduit includes a conduit connecting the pilot burner conduit with the main burner conduit and a third valve Cooperating with the ,Conduit between the pilot burner conduit and the main burner conduit to prevent flow to the main burner conduit from the bypass conduit when the bypass valve is open.

12 A safety valve arrangement according to claim 1 in which operation of the resetting means is operative to close the bypass valve so closure of the valve means shuts off all ow to both burner conduits.

13. A safety valve arrangement according to claim 1 in which the resetting means includes means requiring cocking before the resetting means is operative to act on the valve means to open the valve means.

14. A safety valve arrangement according to claim 1? in which the resetting means and the bypass valve have a common actuator and movement of the actuator to .open the bypas valve and to move the resetting means in the l5. A safety valve arrangement according to claim 14 in which said actuatorV is biased in the Adirection to close the bypass valve and move the resetting vmeans in the vresetting direction.

16. A safety valve arrangement according to claim 1 in which the resetting meansincludes Ia stemof insufieient length to reset the valve means and including means to temporarily add sufficient length to the stem to reset the valve means. n

17. ln a safe lighting `mechanism for burners, a main burner conduit, a pilot burner conduit, and a conduit Supplying fuel to the main bor-oer conduit and the pilot burner' conduit, valve means in said supply conduit, means biasing said valve means to a Closed position, a bypass conduit around said valve means from said supply conduit to said pilot burner conduit, a bypass valve in said hypass conduit, means for opening said bypass valve to supply fuel to 4said lpilot burner conduit, resetting means for opening said val-ve means and holding it open for a short period of time only, and means operative to hold said valve means open against the bias of said biasing means in response to a control condition.

18. A safe lighting mechanism according to claim 17 in which said resetting means closes said bypass valve during the resetting operation, said bypass valve Abeing open for a short period of time after said valve means is opened to provide an uninterrupted flow of fuel to the pilot burner conduit during the resetting operation.

i 19. VIn `a safe lighting mechanism for fuel burners, a body having a chamber, a Afuel inlet to said chamber, a pilot burner outlet from saidl Chamber, a main burner outlet from said chamber, a valve means in said chamber for controlling the flow of fuel from said fuel inlet to said pilot and main burner outlets, means biasing said valve means to a closed position, a bypass conduit connecting said fuel inlet to said pilot outlet, a bypass valve in said bypass conduit, means for opening said bypass valve to permit fuel to flow to said pilot burner outlet, resetting means to close said bypass valve and open said valve means and hold it open for a short period of time only, and holding means to hold said valve means open against the bias of said biasing means in response to a control condition at the pilot burner outlet.

20. A safe lighting mechanism according to claim 19 in which said resetting means opens said valve means a short period of time before it closes said bypass valve to provide an uninterrupted llow of fuel to the pilot burner outlet during the resetting operation.

2l. A safety valve arrangement according to claim 19 in which said supply conduit includes a flow path between the bypass conduit and the main burner, a third valve interposed in the ow path between the by-pass conduit and the main burner outlet land operatively connected with the by-pass valve to close when the by-pass valve opened and vice versa.

22. A safe lighting mechanism according to claim 19 in which said resetting means includes a stem slidably mounted in said body extending into said chamber but normally insuicient length to open the valve means and provided with means for temporarily elongating said stem when moved axially in one direction and to open said valve means when moved in the opposite direction and to hold said valve means open for the short period of time during which said stem is elongated.

23. A safe lighting mechanism according to claim 22 in which said means for temporarily elongating said stem in cludes a dash pot mechanism having a cup mounted in said chamber with said stem extending into the open end thereof, a piston mounted on said stem and slidable in said cup, a first spring operatively connected between said piston and said cup to bias said piston with respect to said cup toward the bottom of said cup, and a second spring operatively connected between said piston and said body to bias said piston and cup in said opposite direction, both said rst and second springs being compressed when said stem is moved in said one direction.

24. A safety valve larrangement comprising,- a main burner passage, a pilot burner passage and a supply passage supplying fuel to the burner passages, a valve means in the supply passage for controlling flow to the burner passages, means biasing the valve means closed, means operable to hold: the valve open in response to a control condition, the holding means being inoperative to open the valve and requiring the valve means to be reset Iafter closure, and resetting means biased in the resetting direction and operative to reset the valve means to the holding means for a short period of time only so the valve will close when not held by the holding means.

25. A safety valve according to claim 24 in which the resetting means includes means requiring cooking before the resetting means is operative to act on the valve means to `open the valve, said c'ocking means being operative for only a brief time after the resetting means moves in the resetting direction.

References Cited in the le of this patent UNITED STATES PATENTS I 2,257,927 wunsch et a1 oct. 7, 1941 2,275,267 Mueller Mar. 3, 1942 2,288,417 Paille .lune 30, 1942 2,297,718 Ray Oct. 6,1942 2,343,904 Hegwein Mar. 14, 1944 FOREIGN PATENTS 725,495 Germany Sept. 2.3, 1942 UNITED STATES PATENT OFFICE CERTIFICATION OF CORRECTION Patent No. 2,972,354 February 2l, 1961 J Lourdes V., McCarty It is hereby oertified'that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

`Column 3, line 58, for "mean" read um means` m; column 4, line lY for "resettiing" read -mresetting e-g/ line Ilx for and to move the resetting means in the" read e als-o acts to cock the resetting means. ee; column 5E line 26 aft-er "normally" insert of Signed and sealed this'th day of August 1961..

(SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents