US2564863A - Ignition and automatic pilot control for fuel burners - Google Patents

Description

C. K. STROBEL Aug. 21, 1951 IGNITION AND AUTOMATIC PILOT CONTROL FOR FUEL BURNERS 2 Sheets-Sheet 1 Filed Dec. 18, 1950 1 mil-$11 I H INVEN TOR. Charles [K Svabel.

Aug. 21, 1951 c. K. STROBEL 2,564,863

IGNITION AND AUTOMATIC PILOT CONTROL FOR FUEL BURNERS Filed Dec. 18, 1950 2 Sheets-Sheet 2 I 59 x a v r 92- dztalya'c (gluten my. a

INVENTOR.

Cluwle's A? jnobel.

Patented Aug. 21, 1951 um'rao STATES PATENT} OFFICE" IGNITION AND AUTOMATIC PILOT CONTROL FOR FUEL BURNERS Charles K. Strobe], Pittsburgh, Pa., assignor to Robcrtshaw-Fulton Controls Company, Greensburg, Pa., a corporation of Delaware Application December 18, 1950, Serial No. 201,386

12 Claims.

ments, the automaticpilot can be supplied with fuel from a pilot connection on the oven thermostat so that continuous operation is assured. Moreover, this eliminates the need for an auxiliary or stand-by pilot burner while retaining the advantages of socalled'100% shutoff upon extinguishment of the flame.

With these and other objects and advantages in view the invention comprises a dual valve construction for controlling the flow of fuel to the main and pilot burners. The pilot valve is biased to a closed position and is operable by electrical means to an open position. A normally open control switch is provided for the electricially operable means and is operated from the combined oven thermostat and fuel cock during the starting operation.

A thermal timing means is set in operation for maintaining the switch closed for a predetermined period following the starting operation. Means responsive to the pilot .burner serve to operate the main burner valve to open position. Upon termination of the starting period the control switch is opened to deenergize the electrically operable pilot valve means. However, the responsive ineans has a maintaining means associated therewith so that the pilot valve remains open irrespective of the opening of the control switch during the normalrunning period.

Several embodiments of the invention are dis closed in the accompanying drawings wherein:

Fig. 1 is a schematic view of the complete system in conjunction with main and pilot burners,

Fig. 21s a partial schematic view of a modifie form, and

Fig. 3 is a similar partial schematic view of a further modified form.

Referring more particularly to Fig. l, the automatic pilot control and ignition apparatus is shown in conjunction with a main burner I0 which is supplied with fuel by a main fuel pipe 12. A pilot burner I4 is disposed in lighting proximity to the main burner l0 and is supplied with fuel by way of a conduit 16 from the main fuel pipe l2.

Interposed in both the main fuel pipe l2 and the conduit I6 is a dual valve construction designated generally by the reference numeral l8.

Positioned in the main fuel pipe I2 ahead of the dual valve construction I8 is a manually operable control means, such as a gas cock 20 which is rotatable between open and closed positions by a handle 2|. It will be understood that the gas cock 20 may be a component part of an oven thermostat (not shown) responsive to the heat of the main burner Ill but, as such combinations are well-known to those skilled in the art, further description is deemed unnecessary. In either arrangement, the conventional safety feature of requiring an inward motion of the handle 2| before rotation thereof is preferably retained for reasons apparent hereinafter. The conduit I6 is connected to the gas cock 20 to receive a supply of fuel at all times that the fuel is supplied to the main fuel pipe l2. In the event that the combined thermostat and gas cook previously mentioned is utilized then the conduit l6 would be connected as the pilot connection on the thermostat so that unthrottled gas would be supplied to the pilot burner I4.

Dual valve construction Referring now more particularly to the dual valve construction I8, the arrangement comprises a valve casing 22 having an inlet 24 for the main fuel pipe l2 from the gas cook 20. An outlet 26 in the valve casing 22 is provided for connection with the opposite end of the main fuel pipe l2 leading to the main burner Ill. A hollow partition 28 is formed in the valvecasing 22 intermediate the inlet 24 and outlet 26 and is provided with a valve seat 30. A main-valve member 32 is cooperable with the valve seat 30 for opening and closing the passage for fuel between the inlet 24 and the outlet 26 through the hollow partition 28.

Movement of the main valve member 32 between open and closed positions is'eifected by means responsive to a flame at the pilot burner ll. This means takes the form of a thermally responsive device having a bulb 34, a capillary tube 36 and an actuating element 38 of expansible form and positioned within the valve casing 22. The thermally responsive means so formed contains a thermally sensitive fluid, such as mercury, so that when the bulb 34 which is located to be heated by a flame at the pilot' burner l4 becomes heated, then the fluid will expand or become vaporized causing corresponding expansion of the actuating element 38. A connecting stem 40 extends between the actuating element 38 and the valve member 32 for "transmitting movement therebetween, it being understood that the valve member 32 is maintained in engagement with the valve seat 36 when the bulb member 34 is unheated.

The valve casing 22 is provided with a second inlet 42 for connection with the conduit I6 from the gas cock 20. A second outlet 44 is also provided in the valve casing 22 for connection with the opposite end of the conduit l6 leading to the pilot burner l4. A second hollow partition 46 having a valve seat 48 formed thereon is provided between the inlet 42 and the outlet 44. A pilot valve member 56 is cooperable with the valve seat 48 for opening and closing communication between the inlet 42 and the outlet 44 through the hollow partition 46. The pilot valve member 58 is normally biased toward the valve seat 48 by gravity, spring or other means. An operating stem 52 extends from the pilot valve member 50 into a solenoid housing 54 formed on the valve casing 22 and being provided with the usual winding 56. The operating stem 52 forms the core of the solenoid operator and the arrangement is such that upon energization of the winding 56, the valve member 56 will be maintained in open position relative to the valve seat 48.

The pilot valve member 50 is also adapted to be moved to open position relative to the valve seat 48 by means operative when the winding 56 of the solenoid operator is deenergized. This means takes the form of an operating stem 58 extending from the main valve member 32 through the hollow partition 46 into operative engagement with the pilot valve member 50. The operating stem 58 is supported in a guide member 60 formed in the casing 22 between the partitions 28 and 46. The guide member 60 is provided with a suitable packing gland 62 to prevent leakage of fuel between the portion of the casing 22 housing the pilot valve member 50 and the portion housing the main valve member 32.

Thermal timing means A thermal timing means is employed for controlling the energization of the winding 56 and is contained in a housing 64 positioned adjacent the gas cook 20. comprises a bimetal element 66 which is biased to the full-line position shown by a tension spring 61 operative between the housing 64 and the bimetal element 66. An electric heater in the form of a heater coil 68 is located in heating proximity of the bimetal element 66. When the bimetal element is sufficiently warped when heated, it will occupy the broken-line position shown in the drawing. In such position, a latching lever pivoted in the housing 64 engages the bimetal element 66 and prevents it from returning to its biased position even if unheated. Thus, the latching lever 16 is biased by gravity, spring or other means to a position in which it serves tomaintain the bimetal element 66 in an inoperative position as will now become apparent.

A normally open control switch comprising relatively fixed and movable contacts 12, 14 respectively is positioned in the housing 64. The movable contact 14 is operable by the latching lever 18 upon pivotal movement thereof to make contact with the fixed contact '12 and establish The thermal timing means a circuit for the heater coil 68 which will be traced hereinafter. A plunger I8 is mounted in the housing 64 for operative engagement with the latching lever 10 to effect the desired pivotal movement out of latching engagement. The plunger 18 projects exteriorly of the housing 64 and is biased by a coil spring away from the latching lever 16, such movement being limited y a stop collar 82 carried by the plunger 18. Movement of the plunger 18 inwardly of the housing 64 is preferably effected by an operating bar 84 carried by the handle 2| of the gas cook 20 which will engage the plunger 18 when the gas cook 20 is closed. However, the bar 84 may be dispensed with, if desired, for a simple pushbutton arrangement directly on the plunger 18.

A timing device such as a clock 86 is provided for setting the starting time of the apparatus. The clock 86 may be electrically operated or of the mechanical type. Ignition means comprising an electrical catalytic igniter 88 is provided for the pilot burner l4. The electric circuit includes a step-down transformer having its primary connected to linewires LI and L2 and the various components of the system are connected to the secondary. It should be observed that the igniter is of the continuously energized type and is connected by wires 81, 89 in series circuit with the secondary of transformer 90. The remaining electrical connections will appear in the following description of the operation of the apparatus.

Operation of Fig. 1 embodiment In the operation of the apparatus it may be assumed that all fuel is cut-off and a starting operation to bring the parts to the positions shown in Fig. 1 is to be conducted. Hence, the initial inward movement of the gas cook handle 2| prior to rotation of the gas cock 26 is sufiicient to operate the plunger 18 and move the contacts l2, 14 to closed position. The contacts 12, 14 are retained in such position by the bimetal element assuming the full-line position under bias of the spring 61. The gas cook 20 is then rotated to open position and the plunger 18 retracts under bias of the spring 80 away from the latching lever 10.

A circuit is then established as follows: one terminal of the secondary of transformer 96, wire 89, wire 92, contacts 12, 14, wire 94, heater coil 68, wire 96, solenoid winding 56, wire 98, time clock 86, wire I80, and wire 8'! to the other terminal of the secondary of transformer 99. If this circuit is closed by the setting of time clock 86, then the winding 56 becomes energized to attract the stem 52 and open the pilot valve member 50. The fuel from the main fuel pipe 12 passes the gas cock 20 to the conduit l6, inlet 42 and outlet 44 of the dual valve construction l8 and thence to the pilot burner 14 where it is ignited by the catalytic igniter 88.

The bulb 34 becomes heated by the pilot flame and causes expansion of the actuating element 38 for operating the stem 40 to open the main valve member 32. The fuel from the main fuel pipe I2 is now admitted from the inlet 24 of the dual valve construction l8 to the outlet 26 thereof and to the main burner I0 where it is ignited by the flame at the pilot burner l4.

During these operations, the heater coil 68 has caused suflicient heating of the bimetal element 66 to cause the warping action to the inoperative position shown in broken-lines. The contacts l2, 14 are opened and the heater coil 68 and winding 56 are both deenergized. The latching shut-oil of fuel described. However,

switch I88 during rotation of the lever II is thus released for movement under its bias to latchin position where the bimetal element is retained in its inoperative or broken-line position irrespective of subsequent cooling and the bias of the tension spring 61. However, the deenergizing of the winding 58 does not effect closing or the pilot valve member ill since the stem 58 is now held in position by the actuating element 88 for holding the pilot valve member Thus, the apparatus is placed in normal running condition with both the main valve member 32 and the pilot valve member 58 held open solely by the action of the thermally responsive means including the bulb 84 and'actuating element 88. The thermostat (not shown) associated with the gas cock 28 can, of course, operate normally to control the flow of fuel in the main fuel pipe 12 while the fuel flow in the pilot conduit I6 is not interrupted.

In the event that the flame at the pilot burner ll becomes extinguished, then the bulb 34 will cool and the actuating element will contract accordingly. The main valve member 32 will be retracted to closed position by the stem 40. Similarly, the stem 58 will be retracted and cease to maintain the pilot valve member 58 in open position. Thus, the desired 100 per cent shut-off of all fuel is obtained upon failure of the pilot flame. It is conceivable, of course, that upon extinguishment of the pilot burner flame that the catalytic igniter 88 will cause immediate reignition so that the bulb will have insuflicient time to become cooled and cause the complete such immediate reignition is not relied upon in this invention since full safety operation is provided.

It will further be apparent that after the termination of operation due to failure of the pilot flame that a manual restarting operation is required. In such operation the gas cock 28 can be operated and with the clock timer 88 set to some later time the system will not go into operation until such a time as determined by the clock setting.

Fig. 2 embodiment In the embodiment shown in Fig. 2, an electrical operation of the thermal timing device instead of the manual operation is provided. To this end, a solenoid operator I82 is connected to the latching element 10 of the previous embodiment and provided with a winding I84. Otherwise, the apparatus remains as previously described except that the handle 2! of the' as cook 28 is provided with an operating pin I88 in place of'the bar 84 to operate a momentary contact gas cock 2.

to open position.

Since the operation of the-embodiment disclosed in Fig. 2 is modified from that described in connection with Fig. 1 only in respect-to the means for operating latching element 18 further description is deemed unnecessary.

Fig. 3 embodiment ill) o the starting and running times or the pilot burner M can be predetermined.

In the operation of the modified form shown in Fig. 3. the switch H4 serves to connect one side of the valve Ill and one side of the circuit containing the coil 88. coil 88 and contacts 12. It in series to the secondary supply line ll. Thus, two parallel circuits are established across the secondary supply lines 81, 88 by closure of the switch 4. Consequently, upon opening of the pilot valve member 58, the flow of fuel to the pilot burner 14 will be established whenever the time clock 8 operates to close the circuit controlled by the switch Ill. This circuit will remain established despite opening of the control switch contacts I2. II as previously described since a separate circuit for the solenoid valve 1 II is established from wire 81, wire I28, switch 4, wire H6, solenoid valve H2, wire Ill and wire 88. However, when the time clock I operates to open the switch I I4 then the last traced circuit will be broken and the solenoid valve HI will close to shut-oil flow of fuel to the pilot burner Ill.

It will be understood that the illustrated forms of the various embodiments of the invention are schematic only and various modifications will occur to those skilled in the art without departing from the scope of the invention as defined in the appended claims.

I claim:

1. An automatic pilot control for iluid fuel burners having main and pilot burners, comprising pilot valve means including a seat and a pilot valve member cooperable with said seat for controlling the flow of fuel to the pilot burner. said pilot valve member being biased to a closed position, main valve means including a seat and a main valve member cooperable with said seat for controlling the flow of fuel to the main burner, electrically operable means for moving said pilot valve member to open position, a normally open control switch for said electrically operable means, means operable for closing said control switch'and energizing said electrically operable means including thermal timing means operable after a predetermined period following said switch closing operation for releasing said control switch for opening movement thereof, means responsive to a flame at the pilot burner for operating said main valve member to open position, and means effective in the open position of said main valve member for maintaining said pilot valve member in open position irrespective of said opening movement of said control switch.

2. An automatic pilot control as claimed in claim 1 wherein said thermal timing means comprises a bimetal element biased to an operative position for holding said control switch closed. an electric heater for causing movement of said bimetal element to an inoperative position upon expiration of said predetermined period, latching means for maintaining said bimetal element in said inoperative position, and means for releasing said latching means for movement of said bimetal element to said operative position.

3. An automatic pilot control as defined in claim 2 wherein a main fuel cock is movable between open and closed positions for controlling flow of fuel to said main valve member. and means operably associated with said cock for operatin said releasing means when said cock is moved to open position.

4. An ignition and automatic pilot control for aeeaeee fluid fuel b ners having main and pilot burners, comprising pilot valve means including a seat and a valve member cooperable with said seat for controlling the flow of fuel to the pilot burner, said pilot valve member being biased to a closed position, main valve means including a seat and a valve member cooperable with said seat for controlling the flow of fuel to the main burner, electrically operable means for moving said pilot valve member to open position, a normally open control switch for said electrically operable means, an electric catalytic igniter connected in parallel circuit with said electrically operable means and located for producing a flame at the-pilot burner, means operable for closing said control switch and energizing said electrically operable means including a bimetal element biased to an operative position for holding said control switch closed, an electric heater in series circuit with said electrically operable means for causing movement of said bimetal element to an inoperative position upon expiration of a predetermined period following said switch closing operation, latching means for maintaining said bimetal element in said inop erative position, and manually operable means for releasing said latching means for movement of said bimetal element to said operative position.

5. An ignition and automatic pilot control as claimed in claim 4 wherein said manually operable means includes'a main fuel cock movable between open and closed positions for controlling the flow of fuel to said main valve member, and means operably associated with said cock for releasing said latching means for movement of said bimetal element to said operative position. 6. An ignition and automatic pilot control as claimed in claim 5 wherein said last means comprise a second electrically operable means operably associated with said latching means, said second electrically operable means being connected in parallel circuit with said first electrically operable means and said electric heater, a second normally open control switch for said second electrically operable means, and switch operating means carried by said manually operable means for closing saidsecond control switch when said cock is moved to open position.

7. An ignition and automatic pilot control for fluid fuel burners having main and pilot burners, comprising pilot valve means including a seat and a valve member cooperable with said seat for controlling the flow of fuel to the pilot burner, said pilot valve member being biased to a closed position, main valve means including a seat and a valve member cooperable with said seat for controlling the flow of fuel to the main burner, electrically operable means for moving said pilot valve member to open position, a normally open control switch for said electrically operable means, an electric catalytic igniter connected in parallel circuit with said electrically operable means and located for producing a flame at the pilot burner, means operable for closing said control switch and energizing said electrically operable means including a bimetal element biased to an operative position for holding said control switch closed, an electric heater in series circuit with said electrically operable means for causing movement of said bimetal element to an inoperative position upon expiration of a predetermined period following said switch closing operation, latching means for maintaining said bimetal element in said inoperative position, means responsive to a flame at the pilot burner for operating said main valve member to Open position, and actuating means effective in the open position of said main valve member for maintaining said pilot valve member in open position irrespective of said opening movement of said control switch.

8. An ignition and automatic pilot control as claimed in claim 7 wherein said flame responsive means includes an expansible element operatively associated with said main valve member, said actuating means comprising a stem connected to said main valve member and operably associated with said pilot valve member.

9. An ignition and automatic pilot control for fluid fuel burners having main and pilot burners, comprising pilot valve means including a seat and a valve member cooperable with said seat for controlling the flow of fuel to the pilot burner, said pilot valve member being biased to a closed position, main valve means including a seat and a valve member cooperable with said seat for controlling the flow of fuel to the main burner, electrically operable means for moving said pilot valve member to open position, a normally open control switch for said electrically operable means, an electrically operable timing device in series circuit with said electrically operable means for predetermining the starting time of the pilot burner, an electric catalytic igniter connected in parallel circuit with said electrically operable means and said timing device for. producing a flame at the pilot burner, means operable for closing said control switch and energizing said electrically operable means including thermal timing means operable after a predetermined period following said switch closing operation for releasing said control switch for opening movement thereof, means responsive to a flame at the pilot burner for operating said main valve member to open position, and means effective in the open position of said main valve member for maintaining said pilot valve member in open position irrespective of said opening movement of said control switch.

10. An ignition and automatic pilot control as claimed in claim 9 wherein said thermal timing means comprises a bimetal element biased to an operative position for holding said control switch closed, an electric heater in series circuit with said electrically operable means and said timing device for causing movement of said bimetal element to an inoperative position upon expiration of said predetermined period, latching means for maintaining said bimetal element in said inoperative position, and means for releasing said latching means for movement of said bimetal element to said operative position.

11. An ignition and automatic pilot control as claimed in claim 10 wherein said last means comprise a second electrically operable means operably associated with said latching means, said second electrically operable means being connected in parallel circuit with said first electrically operable means and said electric heater, 9. second normally open control switch for said second electrically operable means, and switch operating means carried by said manually operable means for closing said second control switch when said cock is moved to open position.

12. An ignition and automatic pilot control for fluid fuel burners having main and pilot burners, comprising pilot valve means including a. seat and a valve member cooperable with said seat for controlling the flow or fuel to the pilot burner, said pilot valve member being biased to a closed position, mainvalve means including a seat and a valve member cooperable with said seat for controlling the flow of fuel to the main burner, electrically operable means for moving said pilot valve member to open position, a normally open control switch for said electrically operable means, an electric catalytic igniter connected in parallel circuit with said electrically operable means and located for producing a flame at the pilot burner, means operable for closing said con-' trol switch and energizing said electrically operable means including thermal timing means operable after a predetermined period following said switch closing operation for releasing said 10 control switch for opening movement thereof, an electrically operable timing device in circuit with said electrically operable means, means controlled by said timing device for controlling the flow of fuel from said pilot valve means to the pilot burner for predetermining the starting and running times of the pilot burner, means responsive to a flame at the pilot burner for operating said main valve member to open position, and means effective in the open position of said main valve member for maintaining said pilot valve member in open position irrespective of said opening movement of said control switch.

CHARLES K. STROBEL.

No references cited.

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