US2355436A - Thermally responsive control switch for liquid fuel lines - Google Patents

Description

Aug. 8, 1944. B. HAYTER 2,355,436

THERMALLY RESPONSIVE CONTROL SWiTCH FOR LIQUID FUEL LINES FiledMarch 13, 1941 2 Sheets-Sheet 1 I n-uenzor .Bruca jfa-zyier B.- HAwr'ER 2,355,436

THERMALLY RESPONSIVE CONTROL SWITCH FOR LIQUID FUEL LINES Aug. 8, 1944.

Filed March 13, 1941 2 Sheets-Sheet 2 hum ' Invefizor .257" 3. 9

mjfazifir Patented Aug. 8, 1944 THERMALLY- RESPONSIVE CONTROL SWITCH FOB LIQUID FUEL LINES .Bruce Hayter, Santa Fe, N. Men, assignor to Oil Devices, Santa Fe, N. Men, a

ship of Illinois limitedpartner Application March 13, 1941, Serial No. 383,119 1 Claim. (CI-1H8) My invention relates to an improvement in control devices forgoil burners and the like, and has for one purpose the provision of means for controlling or varying the fiow of fuel to a liquid fuel burner in response to changes in the temperature conditions adjacent the burner.

Another purpose is the provision of a control device for use with pot type burners which oper-' ates in response to an undesired increase in temperature at or adjacent the pot.

Another purpose is the provision of means for cutting 011 or reducing fuel fiow to a pot type burner-having a booster fan in response to failure -of the fan or fan' motor.

Other purposes will appear from time to time in the course of the specification and claim. I illustrate my invention more or less diagrammatically in the accompanying drawings wherein:

Fig. 1 is a vertical section; Fig. 2 is a partial vertical section on an enlarged scale of a variant form of the device;

Fig. 3 is a partial vertical section illustrating a variant form of switch; 1 Fig. 4 is a similar section illustrating a still further variant form of switch; and

Fig. 5 illustrates a variant form of switch control. Like parts are indicated by like symbols throughout the specification and drawings.

Referring to the drawings, I generally indicates a heater drum, which may for example have supporting legs 2. 2 indicates a potlocated within the drum and having a plurality of primary air inlet apertures l and a top row of secondary air inlet apertures i. t is any suitable fire ring havsource of electric power, which may for example be a transformer. 2| is a connection between the thermostatic contact Ito and the transformer.

2| is a resistance mounted on or in the valve housing generally indicated as H, and for convenience shown as mounted adjacent awarping bar 22, both being mounted as upon a bracket 23 on the partition or support 24 within the housing cover 2!. The resistance 2! is shown as in circuit with the transformer is as by the conductor 26. 21 and 20 indicate conductors extending respec-- tively from the resistance 2| and the thermostatic fixed contact Ila to any suitable heat responsive member generally indicated as 29 and located for cmvenience adjacent the pot l. I may find it convenient to locate it on the partition l2 below but close to the bottom of the pot 3. I

may employ any thermostatically responsive element but for convenience I illustrate a snap disc ll associated with the'conductor 2| and the fixed contact ll associated with the conductor 21.

I It will be understood that the members 30,- may normally be in circuit closing relation but that, in response to a predetermined increase in the temperature of or about the switch, the member 2! may snap into circuit breaking position, which breaks the circuit through the resistance It. The circuit, of course, can be closed only when the thermostatic contacts Ila and llb are in the circuit closing position in which they are shown in Fig. 1.

when the heat to which the switch 29 is subjected ing a central aperture I. I indicates a foramiable motor IS, the fan and motor, if desired, beingmounted on a unitary supporting plate I. spaced below the partition I2 as by any suitable spacers It will be understood that any suitable circuit may be providedwhereby the motor II may be constantly operated from any suitable source of electric power.-- ll indicatesa thermostat, which may have a normally fixed adjustable contact I its and a movable contact llb, which may for example be a bimetallic strip. I! is any suitable does not exceed a predetermined maximum, the circuit through the resistance 2| is closed.

ll indicates any suitable valve stem having a limit abutment disc ll, between which and the bracket 42 is compressed a spring 43. The

' bracket 42 may serve as a bearing for the valve stem I, and the spring I! normally tends to urge the valve stem upwardiy as far as the limit disc II and the adjustable limit stop 44 will permit. Hie valve stem 4| may haves valve member proper I, which may have any suitable metering be understood, however, that,-unless a circuit is closed through the resistance 2|,

the warping bar 22 remains in the bottom or full line position in it is Fig. 1, in which. position it The parts are so arranged that tion.

is effective to hold the valve stem 40 in bottom position against the compression of the spring 43, and it is only when a circuit is closed through the resistance 2| that the resistance causes the warping bar 22 to rise to its dotted line or top position of Fig. l.

Any suitable circuit may be used, extending from the motor I5 to the transformer l9, if constant operation is desired, or the motor circuit may be controlled by a room thermostat where its intermittent operation is desired.

In the operation of the device, when heat is called for and the thermostatic contacts Ilia and l8-b are as shown in the circuit closing position of Fig. 1, the circuit is closed through the resistance 2|, the Warping bar 22 is warped up to the dotted line or release position, and the spring 43 raises the valve stem to full flow position, and a full flow of fuel is admitted. At that time the motor I5 is in operation. The fan It is effective to deliver air under pressure to the space about the pot 3. This delivery of air not merely provides the air necessary for combustion but has a cooling effect on the switch or the space immediately about it.

If for any reason the fan fails, this cooling eifect ceases and the switch 29 or the space about it increases in temperature sufficiently to cause the member 30 to snap into circuit breaking position. It will stay in circuit breaking position until the temperature of the pot, and thus of the space around the switch 29, becomes reduced because of the reduced flow of fuel which ensues. If before the device has any further attention the pot becomes so far cooled as to permit the member 30 again to snap into circuit closing position, the fuel supply will again be reduced as soon as the space around the switch become overheated because of the increased supply of fuel. In other words, the fuel supply will be intermittent,-and the total heating effect will be reduced.

I may find it desirable, as shown in Fig. 3, to provide means for preventing the member 30 from snapping back into circuit closing position. I may, for example, have any suitable abutment member or plunger 50, which may be guided by any suitable guide 5|, and which i urged by a spring 52 in the direction of the snap switch member 30. When the snap switch member 30 is in the circuit closing position in which it isshown in dotted line in Fig. 3, its edge engages the plunger 50 and resists the effectof the compression of the spring 52. When the member 30 snaps or flexes into theraised or circuit breaking position of Fig. 3, the spring 52 is then effective to move the plunger 50 beneath the outer edge of the member 30 to prevent it from thereafter snapping back unless and until the operator pulls on the-actuating rod 53 by the exterior control handle 54 to release the member 30 again to its bottom or circuit closing position of Fig. 3. In Fig. 3 the dotted line position of the member 50 indicates its release position, and it is shown in full line as holding the member 30 also in full line position in its raised or circuit breaking posian alternative form may be employed, as shown for example in Fig. 4. In that form I illustrate as opposed to the fixed contact 3| a warping bar 56, which is normally held in circuit closing posi- The fixed contact 3| and the Warping bar 56 may be mounted on any suitable base element 51, which may be applied for example to the partition I2. 58 indicates a trigger which may be spring thrust as by the spring 59 and the abutment 60 into position to snap under the outer end of the warping bar 56 when the warping bar rises to circuit breaking position. Any suitable exterior handle Bl, with the control rod 62, is effective to release the trigger 58 when desired and to permit the warping bar 55 to warp back into circuit closing position.

Fig. 2 illustrates a variant form of the device, which I illustrate in connection with the same switch 29, as shown in Fig. 1, but which it will be understood may inferentially include the switch of either of the forms of Figs. 3 and 4. Fig. 2 illustrates my control as applicable to a multi-stage burner. The pot 3 with the bafile housing 8 will be understood inferentially to be included in Fig. 2.

Referring to Fig. 2, I illustrate the top of the valve stem, as at 10, normally urged into open position as by the spring 'll. Its upward movement is initially resisted by the warping bar 12, the setting of which may be controlled by the adjustable stop 13. This stop may be set to give a minimum or pilot flow, or if the switch were employed with the structure without a pilot, it might be set for a complete shutofi of fuel. Associated with the warping bar 12 is a'resistance 14, shown as in circuit with the fixed adjustable contact 15, which in turn is opposed to the movable contact I6 of any suitable thermostat. TI is a transformer or other suitable power source, in circuit with the room thermostat and with the resistance 14. It will be understood that with the switch 29 normally in circuit closing position, a: movement of the thermostatic contact 16 into conductiverelation with the fixed contact 15 will close a circuit through the resistance 14 and will cause the warping bar 12 to warp rapidly upwardly to permit the spring H to raise the valve. The upward movement of the valve 10 is stopped at an intermediate fiow position by a second warping bar.'|8, the downward position of which is limited by any suitable adjusting stop 19. The resistance I2 is in circuit with the switch 29, and with a secincluded inthe circuit for the resistance "M of the warping bar 12, but. it is included in the circuit for the resistance 82 of the warping bar 18. Thus .the safety provision or turndown feature is effecfor the resistance I4 through the contacts 15 and 16. This permits the valve Ill to;rise ashigh as the still cold warping. bar 18 will. permit'. vUnless further heat is called'for, this is.as,- far as the valve stem can rise. If still further. heat is called for, the thermostat is 'eifective tojmove the movable contact 8| into'circuit closing-relationship with the contact 8l'l. This closes a' cir- 4 cuit'through the resistance' 82 for 'thesecond wraping bar 18, which circuit, however, can only be closed if the contacts of the switch 29 or its equivalent are in circuit closing position. The result then is to flex the-bar 18 high enough to permit the springll to move the valve-, 'stem 10 to a fully-open position, controlled or limited by the 'adjustable stop 83 or its equivalent.

-- It will be understood that themotori 5is-operating at least during the high stage. If the motor II, which is inferentially present in Fig. 2, for any reason stops operating, then the cooling effect, of the fan on the switch 29 ceases, and the switch 29 shortly moves to circuit breaking position, which breaks the circuit for the resistance 82 and causes the warping bar 18 to move the valve stem back to the intermediate flow position. It is understood that the parts are so proportioned that at intermediate flow position the device may operate on natural draft and that non-operation of the motor and fan at the intermediate stage is not harmful.

It will be understood, of course, that in place of the particular switch 29, shown in Fig. 2, with the fixed contact 3| and the snap disc 30, I may substitute either of the switch structures shown in Figs. 3 and 4, which in both cases show means for holding the circuit open once it has been broken by the change in heat conditions, until the operator again releases either the plunger 50 of Fig. 3' or the trigger 5 8 of Fig. 4.

Referring to Fig. 5, I illustrate a switch control, which is shown as substantially identical with the switch structure of Fig. 4 except that in the place of the pivoted trigger 58, I illustrate a wanping bar 9|! mounted on any suitable base or bracket 9|, with which is associated at resistance 82, in circuit with the thermostat and the transformer. It will thus be seen that a circuit is closed through the resistance 92 at all times that the thermostatic contacts I81; and lab are in circuit closing position.

It will be understood that, when the resistance 92 is heated, it causes the warping bar 90 to tend. to flex against the end of the switch element 58 in such fashion that whenever the switch element or warping bar 56 warps upwardly to circult breaking position, the end of the warping bar warps in beneath it and prevents it from again returning to circuit closing position. -I illustrate an exterior manual knob 93, which, through any suitable tension member 94, may be employed manually to withdraw the warping bar 90 to permit the downward movement of the warping bar 56. This manual operation may be made unnecessary by an opening of the thermostatic contacts which will break the circuit through the resistance 92 and permit the warping bar 80 to warp into inoperative position. 0therwise the control, so far as the valve is con- .cerned, is the same.

grammatic, rather than as limiting me to my precise showing.

I claim: 1 I

In combination, a pot type burner, a fuel line therefor, a valve controlling the fuel line, electrically actuated means for controlling the valve, a circuit including said means and adapted when energized to open the valve, the burner including a pot, an air chamber and a fan, a thermostatically actuated switch in the air chamber exposed to the flow of air fromthe fan, contacts associated with said switch adapted to close the circuit when the thermostatically actuated switch is in a cold condition and to open the circuit when the switch is heated said thermostatically actuated switch being subjected directly to the heat of the pot.

BRUCE HAY'I'ER.

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