US2416766A - Fuel supply and ignition control for combustion apparatus - Google Patents

Description

March 4, 1947. V J. w; MILLER ETAL 2,416,756 FUEL SUPPLY AND IGNITION CONTROL FOR COMBUSTION APPARATUS Filed May 27, 1942 2 Sheets-Shed 1 HOV-L III/III I ELIlI-Ill' IIIIIIIIIIIII/ I March 4, 1947.

, J. MILLER ET'AI."

EUEL SUPPLY AND IGNITION CONTROL FOR COIBUSTION APPARATUS- Filed May 27. 1942 NOV 2 sheets-sheet 2 FIG 7 Y mvm on JOHN y. MlLLER BY RAYMdNfi E. FELL a Patented 4, 1947 FUEL SUPPLY AND IGNITION CONTROL FOR COMBUSTION srrnas'rus John W. Miller and Raymond E. Fell, Lansing, Mich., assignors to Motor Wheel Corporation, Lansing. Michl, a corporation of Michigan Application May 27, 1942, Serial No. 444,710

Claims. (Cl. 15828) 1 This invention relates to control systems for the fuel supply and fuel ignition elements of fluid fuel burners.

Heretofore it has been the custom to operate some types of burners consuming liquid fuel at or between what is termed high fire and pilot fire. Thus, during the heating season some fuel is being burned continually to maintain at least a pilot fire whether heat is needed or not. At certain times of the year when heat is unnecessary for long periods, that practice is wasteful of fuel.

On the other hand, if the burner is shut off completely, it is necessary to relight the burner whenever heat is required.

The present invention is designed to over-- come the objectionable features of previous control systems. Its principal object is to provide a completely automatic fuel supply control and fuel ignition system for combustion apparatus which will operate to admit fuel to the burner and ignite the same when heat is desired and the burner is cold, and which will completely shut off the fuel when heat is no longer required for relatively long periods. Another object is to provide such a system of controls in which all possibility of explosion due to ignition of fuel by the ignition unit in a hot but unlighted burner is eliminated. A still further object is-to provide a fuel ignition system in which the ignition element is de-energized whenever the burner i's'above a predetermined temperature.

These objects and others ancillary thereto will .more fully appear in the following specification when read in connection with the accompanying drawings, wherein- Figure 1 is a diagrammatic cross-sectional view of a furnace and the controls therefor embodying the invention; I

Figure 2 is a fragmentary cross-sectional view of the burner illustrating the position of the is? nition element and burner switch;

Figure 3 is a fragmentary cross-sectional view of a fuel control embodying a movable fuel regulating valve and its operating means;

Figure 4 is a simplified wiring diagram of the fuel control and ignition system when the burner is cold;

Figure 5 is a view similar to Figure 4 showing the various elements in the position they assume when the room thermostat is closed and the burner is cold;

Figure 6 is a view similar to Figure 4 showing the various parts in the positions they assume when the thermostat is closed and the burner is hot; and

Figure 7 is a view similar to Figure 4 showing I the positions of the parts when the thermostat is open and the burner is hot.

The invention is shown in the drawings in connection with a more or less conventional furnace having a forced air heating system. The furnace comprises a heat exchanger iii in the lower part of which is a burner I of the vaporizing pot type. The burner II is of the type disclosed in the .Valjean Patent No. 2,186,156 granted January 9, .1940. The burner is adapted to burn fuel oil supplied from a suitable source through a conduit '|2. The rate of delivery of fuel is regulated by a fuel control designated generally by the numeral l3. Surrounding the heat exchanger III is a furnace jacket it havi utlet ducts II for conveying heated air to the space to be heated. Air is circulated through the furnace jacket and the ducts It by means of a centrifugal fan l8 driven by an electric motor I'I.

Located within the burner adjacent the fuel inlet is a fuel ignition element 20. This element may be a hot wire adapted when energized to vaporize and ignite the fuel admitted ,to the -to regulate the supply of fuel admitted to the burner. The valve is mounted in the housing 22 for vertical reciprocation relative thereto. The valve 2| is surrounded by a coil spring 22 seated against a shoulder 24 on the valve and another shoulder 25 on the housing. This spring tends to lift the valve 2| from its seat 26 and permit oil to flow into the burner. The maximumopening of the valve 2| is regulated by a screw 21 threaded into a nut 21a secured to the top wall of the housing 22. Threaded onto the upper end of the valve 2| is a collar 28 for a purpose which will appear presently.

Three heat motors 29, 30 and 3| are provided to adjust, the valve 2|. All three of these motors are similar and each comprises a bimetallic strip in heat exchange relation to a heating coil. The heating coils for the three motors are designated by numerals 32, 33 and 34, respectively. Each motor is rigidly secured at one end to a suitable support on a wall of the housing.

Each motor has a different function. Motor 29 is the main valve operatin motor and moves the valve from fully Opened high fire" position to predetermined partially opened "pilot fire" or low fire" positions. Motor 30 is the shut off motor and completely closes the valve under certain conditions. Motor 3| is a limiting device The heat motor 29 has'its freeend positioned above the adjustable collar 28 on the valve. It is so arranged that when cold it assumes the position shown in Figure 3. When heated by the heating coil 32 the motor 29 bends upwardly to permit the valve 2| to be opened by the spring 23 if the valve-is not held in closed position by motor 39. The operation of motor39 will be explained presently. The downward movement of the heat motor 29 when the motor cools is limited by means of an adjusting screw 35 threaded into a suitable support on the housing. This screw is adjusted so that when the heat motor reaches the limiting position determined by the screw 35 the valve is open topermit just enough oil to flow into the burner to maintain a pilot fire.

Heat motor 39 is arranged sothat when cold its free end engages the shoulder 24 on the valve and pushes the latter'clownwardly to its completely closed position, as shown in Figure 3. When heated by the heating coil 33the heat motor bends upwardly to release the valve and permit it to open.

1 The free end of heat motor 3| is turned upwardly and is positioned adjacent the under side of heat motor 29. The heat motor 3| is arranged so that when heated it bends upwardly and when to pilot position but permits the valve to be closed to low fire position. Thus, under certain circumstances which will become more fully apparent hereinafter, the valve can operate only between high fire and low fire. When heat motor 3| is cold, the motor 29 operates as described above between high fire and pilot fire.

1 As shown in Figures 1 and 4 to 7, the control system includes, in addition to the valve 2|, its operating motors 29,39 and 3|, and the ignition element 29, a room thermostat 46, a toggle switch 41, a burner switch-31, a relay switch 49, and a safety switch l9. 7

, The thermostat switch 46 is of any conventional type and is located in the room to be heated. The toggle switch 41 is conventional also. Preferably, but not necessarily, it is located on the thermostat housing.

1 The burner switch 3'! is mounted on the burner II in heat exchange relation thereto. See Figure 2. This burner switch is athermostatically oper- 4,, suitable location. This contacts 4|, 42 and 43. An arm 44 is arranged so that in closed position it short circuits all three of these contacts. In the open position the arm is spaced from the contacts. The arm is moved between its open and closed positions by means of a solenoid 45, the action of whichwill be describedmore fully presently.

The. wiringiof the control system isf illustrated in Figures 1 and 4 to '7. In a general way there i are six circuits more or less dependent upon each other and connected to the same source of electrio current. Current is supplied from the secsafety switch |9 andthermostat switch 46. The

switches are connected in series with each other and with the motor 29. When both switches are closed the motor 29 is heated, it bends upwardly, and permits the valve 2| to open. I

Connected in parallelwith the motor 29 by means of conductors 51, 58, 59 and switch 31' when in the C position, is the solenoid 45 of the relay. Switches 46 and I9 are also in the relay,

circuit. In other words, the part of the'relay circuit containing switches 46 and I9 is a part of the circuit of heat motor 29, so that the relay circuit can be closed only when the heat motor 29 is heated.

The circuit of the ignition element 29 comprises conductors 6|, 69 and 62 and relay switcharm 44. The circuit is in parallel with the circuit of motor 29 and is opened and closed only by relay switch arm 44.

Heat motor 39 hastwo separate circuits. The

, initial circuit, or that in whichmotor 39 is placed when the burner is cold, consists of conductors 54, 69, 6|, 63, 64 and 53 and relay switch arm 44. This circuit is opened and closed only by the a relay switch 49.

The other, or alternate circuit, of heat motor 39 consists of conductors 54, 69, 65, 63, 64 and 53,

, and burner switch 31 when it occupies the H in series with motor 3| and is the sole control for I that motor. I The operation of the system is shown in Figtires 4 to 7. The circuits which are energized are shown in heavy black lines and the circuits in which no electricity is flowing are shown in relatively light lines.

Assuming that the burner is cold and the room is abovethe temperature at which thermostat switch 46 closes, the parts will be in the position shown in Figure 4. In other'words, switches 49 and 46 will be open and switch 31 in the C or rent will fiow through the coil 32 of motor 29 ably this switch 31 is a snap action type of switch.

I The relay switch 49 may be mounted in any cold position engaging the contacts 39. When the room temperature drops below that at which switch 46 is set, that switch will close and ourand through the solenoid 45. The solenoid will pull the switch arm 44 of the relay 49 to closed position so that current flows through the coil 33 of heat motor 39 and simultaneously will flowswitch has three spaced this oil will vaporize and be ignited by the heat from the ignition element 20.

During ashort interval during which the bumer is warming up, the elements of the control system will remain as shown in Figure 5. When the burner reaches the predetermined tempera-' tureat which burner switch 31 is set to operate, the switch 31 will move over to the H or hot position breaking the circuit of the solenoid 45 and simultaneously closing the circuit across the contacts 39. When the solenoid 45 is deenergizcd the relay switch 40 opens, breaking the circuit of the ignition element 20 and the initial circuit of the heat motor 30. The various elements of the system will then be in the positions shown in Figure 6. I It will be seen that in this condition the heat motor 29 is still energized, leaving the fuel valve wide open. The heat motor 30 is also energized to permit the fuel valve to stay in its wide open position because the alternate circuit of motor 29 has been closed by the switch3l. The burner then continues to operate at high fire until the temperature of the room-rises suillciently to open the thermostat 48. When that occurs the elements are in the positions shown in Figure '7. The coil 32 of the heat motor 23 is de-energized to permit the motor to cool and push the valve 2| down to its partially closed position. The fire will then die down to pilot fire and will operate at that rate untilthe room again calls for heat.

If the room again calls for heat within a specified period, say an hour, the thermostat will close and the parts will again assume the positions shown in Figure 6 so that the burner operates at high fire. However, if the room does not call for heat for an extended period the burner will slowly cool down to a temperature-low enough to permit the burner switch 31 to move back to its cold position shown in Figure 4 and break the circuit of the heat motor 30. This heat motor will then cool down and force the valve to its fully closed position shutting off the oil. 'The entire system will then remain in the position shown in Figure 4 until such time as th room thermostat 46 again closes.

It" will be obvious, of course, that the switch 31 can be designed to operate at any desirable temperature, and thereby vary the period during which the burner will operate on pilot fire without shutting the burner completely off.

At certain seasons of the year, particularly during periods of relatively severe temperatures, it is desirable that the burner operate at relatively high temperatures at all times. In other words the burner should operate at a high fire or at a fire somewhere above pilot fire. This is about one-fourth of the burner capacity and is designated as low fire. To accomplish this result, the switch 41 is closed manually which energizes the coil 34 of the heat motor 3i. That causes the heat motor 3| to bend upwardly to the limit determined by the screw 36 and prevents the motor 29 from moving down to the pilot fire position. In other words, the motor 29 is held away from the screw 35 when the motor 3| is heated. or course, to accomplish this result the motor 3i must be more powerful than the motor 29.

When the switch 41 is closed and the burner is operating between low fire and high fire, the burner will never cool down sufficiently to move the switch 31 from the hot to the cold position. Therefore, whenever the switch 4'! is closed the system will be'either in the condition shown 6 in Figure 6, or in the condition shown in Figure. 7, and will never go to theoif" position shownv in Figure '4. I

From the foregoing it will be seen that this invention provides for all contingencies in the operating of a heating system of this type. The

" burner will operate to provide heat when needed at the most emcient rate but will completely the burner when the burner is relatively warm.

shut oil the flow of fuel in periods of very mild weather when heat is not needed for a long time. It also absolutely prevents the possibility of turning onthe ignition element with fuel in Sinc the circuit through the ignition element 20 can not be established unless switch 31 is in the C position, it prevents the ignition of quantities of. fuel vapors which might-form ma warm burner and thereby cause an explosion. It also prevents the now of fu'el'to the burner except when the ignition element is on or when. the burner is operating, since the shut ofl motor 30 is not in an established circuit except when ignition element 20 is heated or switch "is in the H position.

' The scope of the invention is indicated in the appended claims.

We claim:

. 1. Fuel'supply and ignition control means for cal fuel ignition element in the burner, means including an adjustable metering valve for supplying fuel to the burnerv in regulatable quantities, valve operating means for moving said valve between opened and. closed positions, said valve operating means comprising a motor for moving the valve from opened position part way toward closed position and a second motor for moving said valve to fully closed position; a circuit for the first motor; a circuit for the, fuel ignition element, a circuit for the second motor, a holdir'ig circuit for the second motor,means for concurrently closing theflrst three of said circuits, and a. heat responsive switch positioned in heat P exchange relation with the burner movable from a position where it is in said second motor circuit to a position where it is in said holding circuit, said switch being movable'to break the second motor circuit and close the holding circuit upon attainment of predetermined temperature in the burner.

2. Fuel supply and ignition control means for a combustion apparatus embodying a liquid fuel burner, comprising, in combination, an electrical fuel ignition element in the burner, means including an adjustable metering valve for supplying fuel to the burner in regulatable quantities, valve operating means for moving said valve between opened and closed positions, said valve operating means comprising a motor for moving said valve fromopened position part 'way toward closed position and a second motor for moving saidvalve to fully closed position, a circuit for the first motor. including a thermostatic switch responsive to the temperature of the space to be heated, a circuit for the ignition element and a circuit for the second motor including a relay switch common to both of the said last named circuits, a relay motor for operating 'said last named switch, a circuit for said relay motor, a holding circuit for the second motor, and means for closing the circuits of the second motor and the relay motor comprising a thermostatic switch in heat exchange relation to the burner and movable from a position where it 1 plying fuel to the burner in regulatable quantities, valve operating means for moving said valve between opened and closed positions, said valve operating means comprising a heat motor for moving the valve fromopened position part way toward closed position, and a second heat motor for moving said valve to closed position, an electrical circuit for th first motorincluding a room temperature thermostat, an electrical circuit for the ignition element and an electrical. circuit for the second motor including a relay switch common to both circuits, a relay call for operating said relay switch, an electrical circuit for said relay coil, a holding circult for said second motor, a heat responsive switch positioned in' heat exchange relation with the burner and movable from a position wherein it closes the relay coil circuit and thereby closes said'relay switch when the burner is below a predetermined temperature to a position where it opens the relay coil circuit and simultaneouslycloses the holding circuit of the second motor'when the burner is above a predetermined temperature. 1 i

4. Fuel supply and ignition control means for combustion apparatus embodying a liquid fuel burner, comprising, in combination, an electrical iuel ignition element in said burner, means including an adjustable metering valve for sup plying fuel to the burner in regulatable quantities, means formoving said valve from fully opened position to a predetermined partially closed position, means independent of the second named means for fully closing said valve, electrical means'including' a switch for alter nately rendering said second named means operative' and inoperative, additional means for rendering said third named means inoperative and for energizing said ignition element when the burner is below a predetermined temperature including anothei' means for deenergizing said ignition element and maintaining said third and said switch is closed, said additional means predetermined temperature irrehpective or the position of said witch and fori'endering said third means opei' tive when said switch is open and said burner is below a predetermined temperature. a 5. Fuel supply and ignition control means for combustion apparatus embodying a liquid fuel burner, comprising, in combination, an electrical fuel ignition element in said burner, means means inoperative when said burner is above a ing the first three of said circuits, said last'named,

means including a heat responsive switch in heat exchange relation with the burner movable from a position wherein it closes the second named circuit when said first circuit is closed to a position wherein it opens said second circuitand simultaneously closes said holding circuit.

Thefollowing references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 40 1,707,194 Shivers Mar. 26, 1929 2,337,476 Landon et al Dec. 21, 1943 2,310,494 Russel Feb. 9, 1943 2,178,672 Perkins Nov. 7, 1939 2,117,021 Cotea MaylO, 1938 2,258,043 Brace Oct. 7, 1941 2,251,055 Howard et a1. July 29, 1941 1,834,396 Good Dec. 1, 1931 FOREIGN PA TENTS 0 Number Country Date 164,125 Swiss "Dec. 1, 1933

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