US2381223A - Automatic control for heating systems - Google Patents

Description

1945- w. F. MILLER AUTOMATIC CONTROL FOR K'IEATIIJG SYSTEMS Filed July 22, 1941 3 Sheets-Sheet 1 1 W C wto v IVZZZ/avz/Yfiziier I 1945- w. F. MILLER AUTQMATIC CONTROL FOR HEATING SYSTEMS 3 Sheets-Sheet 2 Filed July 22, 1941 Aug. 7, 1945.

AUTOMATIC CONTROL FOR HEATING SYSTEMS Filed July 22, 1941 3 Sheets-Sheet 3 3 vvu e/vvboo WzllzlazzmzZzer w. F. MILLER 2,381,223

"'PatentedlAug. 7,;1945

AUTOMATIC CONTROL FOR HEATING SYSTEMS William F. Miller, Evansville, .Ind., assignor to Industiial Engineering Corporation, a corporation of Indiana Application July 22, 1941, Serial No. 403,566

7 Claims.

The present invention relates to improvements in automatic controls for heating systems and the like and aims generally to improve existing controls by providing a positive mechanism under the control of the room thermostat or a time controlled initiator or both that will effectively. emcientlrand safely deliver fuel and air to the jfurna'ce and control the burningthereof in a highly efllcient manner.

One of the objects of-the invention is to-provide a simple and-efficient control that is adaptable for the control of the burning of a variety of fuels, as for example, oil, gas or coal.

A further object of the invention is the provision of a control which is operated through one complete cycle of revolution of a controlling means, insuring positive positioning of the several supply means and the starting of each succeeding cycle. l

A further object of the invention is the provision of a simplified control having positive means for regulating the time of starting and stopping the supply .of fueland air under pressure to the combustion chamber with means to change or vary the duration thereof at the will of the operator.

A further and more specific object of the invention is the provision of a control for oil burners of the so-called pot type, embodying an oil supply line and blower, in which the supply of fuel is delayed until after the operation of the burner is commenced, and .is terminated substantially prior to the termination of the blower.

A further object of the invention is the provision of a. control mechanism adapted for coal stokers that may be operated to supply fuel for a longer or shorter time than blower operation depending upon the grade of fuel used, thus to insure the most eflicient results.

A still further object is the provision of an improved control for gas burners employing a plurality of banks or sets of gas burners to insure operation of the burners in a most eflicient anddesirable manner.

Many other objects and advantages of the in-' vention will be apparent to those skilled in the art in view of the following moredetailed description of one form of the invention, such as that illustrated'in the accompanying drawings in which a Fig. l is a front elevation of the panel of the control;

Fig. 2 is a diagrammatic view illustrating one manner of wiring the associated mechanism of the control;

Fig.3 is a diagrammatic view illustrating one lower drops into the recess l4.

manner of employing the control for oil burners;

Fig. 4 is a diagrammatic view illustrating one manner of employing the control for coal stokers;

Fig. 5 is a similar view illustrating another manner of employing the controls for coal stokers; and

Fig. 6 is a diagrammatic view of one manner of employing the control for a plurality of banks of gas burners.

Referring more particularly to the illustrated embodiment of the invention, there is provided a panel ill of any suitable material on which is mounted the associated mechanisms and terminal posts of the control. The panel advantageously may be mounted in a box or casing (not shown) to protect the mechanisms.

A primary controller for the burner advantageously includes a normally idle or inactive time controlled mechanism advantageously comprising an electrically operated clock motor ll having a shaft l2 geared to a predetermined cycle of revolution and carrying primary controlling cams for the several mechanisms of the burner, such as fuel feed, blower and ignition, where electrical ignition is used. The clock motor is advantageously secured to the rear face of the panel and the shaft l2 extends through and may be journalle'd in the panel, so that the primary controlling cams are forwardly of thefront face of the panel and accessible to the user. In the illustrated'form there are two primary controlling cams fastened to the shaft the cam l3 being formed with a recess l4 designed to control the advanced burner mechanism, for example the ignition, or blower or both, and the other cam l5 being formed with a hump l6 designed to control the delayed burner mechanism such as, for example, the fuel supply. It will be understood that these arrangements are merely illustrative and that other orders and mechanisms may be controlled as hereinafter described.

The primary controlling cam I 3 controls the advanced circuit which, in the illustrated form, includes the blower and ignition circuit, through a switch I! which has a follower l8 to close the switch as the follower rides on the outer face i the cam, and to break the switch as the fol- The controlling cam l5 controls the delayed circuit, herein illustrated as the fuel supply. Conveniently the switch I! maybe a single contact switch adapted to supply current through a switch blade ll to a single contact l'l The-switches conventionally may be snap action switches of the types illustrated in Patent No. 1,960,020 of May 22, 1934.

The normally idle primary controller is normally. under the control of an'initiator circuit which includes a. room thermostat. As herein illustrated the room thermostat is advantageously of the double acting type having a high thermostat at 2| and a low thermostat is ordinarily set to open at a temperature of from 1 to 2 degrees higher than the predetermined temperature setting of the thermostat 22, and is designed to prevent operation of the furnace when room temperature reaches such predetermined high degree.

The initiator circuit may also include a continuously operating time controlled mechanism 30 connected in the circuit in parallel with the room thermostat and designed to initiate operation of the primary controller at regular periodic intervals of time as will be more fully described later.

Referring to Fig. 2, the panel is provided with four line voltage terminals, marked l, 2, 3 and 4, and three secondary voltage thermostat terminals marked B, R and W, there being a transformer 40 provided for supplying the secondary voltage. The primary of the transformer is connected through wires 4l--42 and line voltage terminals I and 2, while one side of the transformer secondary is connected by wire 43 to the thermostat terminal R and the other side is connected through wire 44, relay magnet 45 and wire 45 to thermostat terminal W.

The double acting thermostat illustrated in Fig. 2 is such as to set up a high circuit H, between terminals B and W, adapted normally to be closed and opened only when the room temperature exceeds a predetermined value above the setting of the low thermostat 22. The thermostat 22 makes and breaks the low circuit L between contacts R and W, respectively, to actuate the burner when the room temperature falls below a predetermined value and to stop the burner when temperature reaches a predetermined value as determined by the thermostat adjustment setting.

Assuming that the room temperature falls and there is a call for heat, thermostat 22 closes, completing the circuit between terminals R and W, permitting a low voltage current to flow from terminal R, wire 43, secondary of transformer 40, wire 44, relay magnet 45, wire 46 and terminal W, actuating the relay to lift the relay blade contact 41 into contact with an upper contact 48 to close the starting circuit to the primary controller motor II. This motor circuit is as follows:

From line L terminal 2, through wire 49 to clock motor ll, wire 50 to relay blade 41, contact 48, wire 5| to one terminal of double pole switch 19, blade 20, wire 52 to one terminal of normally open switch l'l, wire 53 to line terminal I, and line H. This circuit starts operation of the motor II and rotation of the primary controlling cams l3 and I5.

After completion of any burner operation, the cams l3 and I5 are always re-set and brought to rest at a predetermined position with the follower iii of switch 11 positioned in recess 14 of cam l3 as will be described later.

The starting of the motor, as above described, rotates the cam to thereafter lift the follower l8 (see Fig. 2) and close the switch I! to operate the advanced burner mechanisms, as for example, the blower and ignition mechanism, in the form illustrated in Fig. 3, which may be connected through wires A and A to line terminals 2 and 3 respectively. This circuit is from line L thermostat at 22. The high connected to terminal 2, wire A through blower and ignition mechanism, wire A to terminal 3, wire 54 through closed switch I'l, wire 53 to terminal l and line L. Advantageously the blower and ignition may be operated after a lapse of about 4 seconds from the starting of the motor, in the case of an oil burner installation as illustrated in Figs. 2 and 3.

It is highly desirable, in such installations, that the blower and ignition be operated for a predetermined time prior to the admission of fuel, such as oil, so as to remove from the combustion area any undesirable gases which may remain from the previous burner operation. Accordingly, the admission of oil is controlled by a delayed circuit closed at a predetermined interval of time after the advanced circuit, as for. example, approximately 10 seconds or longer after the blower and ignition are started.

0 The delay in closing the relay and-circuit or starting the fuel supply as above described is determined by the position of the hump l6 of the cam IS in advance of the follower IQ of the double pole switch l9 relative to the recess l4 of the cam I3. As the follower rides on the outer surface of the hump, the switch is actuated to shift the blade 20 to the opposite terminal l9 of the double pole switch, closing the circuit from line L terminal 2, wire F"to fuel supply valve, wire F to terminal 4, wire 55 to double pole switch 19, blade 20, wires 52 and 53 to terminal I and line L During such time as the initiator circuits H and L remain closed and the relay magnet energized, the shifting of the switch blade 20, as above described, breaks the circuit between wires 5| and 52 which supplies current to the motor II and stops the motor in this position, with the follower IS on the high part of hump I6, maintaining both burner mechanism circuits closed, and insuring continuous burner operation until room temperature is satisfied.

When, however, the initiator circuit is broken, as when room temperature has been satisfied, the r; motor II is again actuated to complete the cycle of rotation and return the cams I3-l5 to their original starting position. When breaking of the initiator circuits occurs, the magnet of the relay is de-energized, permitting spring 4'! to move relay blade 41 into contact with lower contact 60, closing the motor circuit as follows: line L wire 49, motor H, wire 50, relay blade 41, contact 60, wire Si, wire 54, closed switch I! wire 53 to terminal I and line L. This actuation of the motor ll starts the recycling or re-setting of the primary controller to its predetermined starting position, during which time the delayed circuit controlled by the switch I9 is opened, stopping the fuel feed in the illustrated form shown in Figs. 2 and 3. During the recycling operation, the blower remains on, because the follower i8 is riding on the high surface of the cam l3, and this is of advantage in completing combustion of any fuel in the combustion pan or other products of combustion in the chamber.

The initiator circuit preferably includes, as stated above, a time controlled mechanism 30 designated to initiate operation of the primary controller at regular periodic intervals of time, and preferably includes a switch connected in the initiator circuit in parallel with the room thermostat circuit L but in. series with the high circuit H. i

As herein illustrated, this time-controlled mech- 5 anism includes continuously operating an electric clock motor 30 supplied with current through wires 3| connected to terminals I and 2,'which in turn are connected to line wires L and L, respectively. The motor 30*- has a shaft 32 extending through the panel Ill and on which is mounted a pair .of relatively adjustable cams 33 and 34, controlling switch blades 35 and 36 as described and claimed in my prior Patent No. 2,190,603, dated February 13, 1940. Adjustment of the cams, relative to each other permits variation of the duration that the switch blades are closed and thus enables the user to vary the duration of periodic operation of the furnace. The cams may be geared to motor 3| to provide any desired time cycle of operation but I prefer, in most instances, to have the cams 32-34 make one revolution each 15 minutes, so that the initiator circuit may be closed for a variable period of from 1 to 7, minutes in each 15 minute cycle.

One of the switch contacts 35 is preferably connected by wire 31 to the terminal B of the high thermostat circuit H, and the other contact 35 is connected by wire 38 to the terminal R which is common to both circuits.

Accordingly, when the high thermostat circuit H is closed, periodic operation of the furnace is controlled by'the switch contacts 35-36 to energize the relay magnet from the secondary of transformer 40 through wire 43, wire 38 ,contacts 35-36, wire 31 to terminal B, through closed high thermostat H to terminal W, wire 46, magnet 45, wire 44 to opposite sides of secondary of transformer 40. Thus when the high thermostat 2| is closed, the time controlled mechanism initiates operation of the primary controller independent of the room thermostat 22, but if room temperature is excessive, thermostat 2i opens and prevents operation of the primary controller by the time controlled mechanism.

The invention isa highly efficient control for oil burners of the pot type as illustrated in Fig. 3, though it will be readily appreciated by those skilled in the art that the invention may be effectively used in other types of furnaces.

Referring to Fig. 3, the connections between the control and the burner mechanism of a pot type oil burner are illustrated. The advanced control circuit controlled by wires A'-A connected to 3 terminals 2 and 3 of the panel advantageously to the blower BI and ignition '62, when electrical i nition is used. The delayed control circuit, controlled by wire F F is connected to a solenoid valve 63 in the fuel oil supply line. Such lines may have a second valve (not shown) as a safety to, close the line in the event of ignition failure asfli's customary in the art.

Assuming that the primary controlled motor H is geared to rotate the cams l3 and l5, one revolution in each minutes, a substantial period of blower and ignition operation is provided, i. e. approximately 4 minutes, after fuel supply is cut off, during which the combustion chamber is purged of all gases, unburned fuel and products of combustion.

The control may be effectively used in the operation of coal stokers, in which case the time-control mechanism 30 acts as a hold-fire or kindlin mechanism.

In some localities the coal available for coal stoker use is relatively slow to ignite, referred to as slow ignition coal. Best results are obtained from the use of such coal if the fan is operated first, to get the coal in the retort burning briskly prior to feeding additional fuel to the rotor. Also, when the room thermostat is satisfied, the fuel mechanisms.

feed should be stopped but the blower should con tinue so as to completely ignite fuel previously fed to the retort.

In such case the burner mechanism of the stoker may be operatedby my improved control by connecting the blower mechanism 65 to the advanced circuit A, A (see Fig, 4) and the coal feed motor 36 to the delayed feed circuit F F where separate burners and fuel feedmotors are provided in the stoker for operating the two Where a single motor is provided in the stoker for operating both the air and fuel feed, the delayed action of the coal feed may be effected by providing a solenoid operated clutch for the fuel feed screw, similar to th clutch B1 of Fig. 5, which is connected in the delayed circuit F F When fast igniting or flash coal is available for stoker use, a different arrangement is desirable. Such coal produces a considerable amount of fiy ash, and it is desirable to feed supply fuel to the retort to build up the fuel in the retort above the level of the tuyre openings toprevent blowing of the fly ash when the blower is started. When the room thermostat is satisfied, it is desirable to stop the operation of the blower, but continue the feeding of fuel to the retort for a sufficient time to again build up a sufficient bed of fuel, to prevent the fuel from being too low in the retort during the idle period.

This function may be efficiently accomplished according to the invention by connecting the coal feed in the advanced circuit A A and the blower in the delayed circuit F F When the stoker provides a single motor for operating the blower and the fuel feed, the fuel feed may be controlled by a magnetic clutch similar to the clutch 61 of Fig. 5.

Alternatively, the advanced circuit A A may control the fuel feed and the delayed circuit F F may control the actuation of a damper motor to open and close the damper.

.Referring to Fig. 6, gas fired furnaces frequently include two or more sets or banks of burners. Such burners may advantageously be operated according to my invention by connecting one set or bank in the advanced circuit A A and the remaining sets in the delayed circuit. When the room thermostat has been satisfied, all of the burners are not cut off, the first set to be lighted remaining open during the re-setting of the primary control, so as to prevent a rapid loss of furnace temperature, providing a more even room temperature.

In the drawings 1 have illustrated the two cams l3 and 15 as fastened to the shaft I2, but it will be apparent to those skilled in the art that these may be relatively adjustable as in the case of the cams 33-34, in cases where i desired to variably adjust the relative positipn ,bf the recess I4 and lobe IE to meet, different conditions of operation.

It will be apparent that while the continuously operating timer 30 is desirable, it may be omitted from the circuit, in whichv case the primary control operates subject only to the room thermostat in exactly the same manner as described above. i

As previously stated, in stoker operation}; the timer 3!) acts as a hold-fire control to supply fuel to the retort periodically, for example, every fifteen minutes, and hold the fire in the retort. As this hold-fire operation should take place regardless of room temperature, it is not advisable to use a double acting thermostat which includes Y pie, though I have shown the blower and ignition connected in parallel in Fig. 3, it is obvious that the control will function. as well if the several elements are connected in series.

I do not intend that the invention be limited beyond the scope of the appended claims.

I claim:

1. An automatic control for heating system having separate fuel and air feeding mechanisms, said control comprising a normally idle controller having a. predetermined position of rest, an initiator circuit including an-electric motor for operating said controller'and a room thermostat for initiating operation of the motor and controller, a plurality of cams on said controller, a switch mechanism controlled by one cam' and electrically connected with said air feeding mechanism, a separate two-way switch mechanism controlled by another of said cams and electrically connected with said fuel feeding mechanism and to the circuit to the controller motor, said cams beingarranged'to initiate operation of said first-named switch and air feeding mechanism in advance of the operation of the fuel feeding switch and mechanism, said twoway switch mechanism opening the circuit to the controller motor when the fuel feeding mechanism circuit is closed to insure operation of the fuel feeding mechanism during such time as said thermostat is closed, and means under the control of the room thermostat for operating the motor to additionally rotate the controller to its predetermined normal position of rest and during such rotation sequentially break the circuit to the fuel feeding mechanism and thereafter to the air feeding mechanism.

2. An automatic controlfor heating systems having separate fuel and air feeding mecha-- nisms, said control comprising a normally idle controller having a predetermined position of rest, an initiator circuit including an electric motor for operating said controller and a room thermostat and a relay adapted'to be closed when room temperature falls below a predetermined value for initiating operation of the motor and air feeding ing mechanism and thereafter to the mechanism. 7

3. An automatic control for heating systems having separate fuel and air feeding mechanisms, said control comprising a normally idle controller having a; predetermined'position of rest, an

initiator circuit including an electric motor for operating said controller and a room thermostat adapted to be closed when room temperature falls 'below a predetermined value for initiating operation of the motor andcontroller, a continuously operating time controlled switch, in. said 'ini-' tiator circuit adapted to operate said electric motor at regular intervals during. such times as the thermostat is open, a plurality of cams on said controller, a switch mechanism controlled by one cam and electrically connected with said air feeding mechanism, a separate two-way s'witch mechanism controlled by another of said cams and electrically connected with said fuel feeding mechanism and-to the circuit to the controller motor, said cams being arranged to initiate operation of said first-named switch and air feeding mechanism in advance of the operation of the two-way switch and fuel feeding mechanism, said two-way switch mechanismopening the -cir'- cuit to the controller motor when the fuel feeding mechanism circuit is closed to insure operation of the fuel feeding mechanism during such time as said thermostat is closed, and means under the control of the room thermostat for operating the motor to additionally rotate the concontroller, a plurality of cams on said controlnism circuit is closed to insure operation of the fuel feeding mechanism during such time as said thermostat is closed, and means controlled by said relay for operating the motor to additionally rotate the controller to its predetermined normal position of rest and during such rotation sequentially break the circuit to the fuel feedtroller to its predetermined normal position of rest and during such rotation sequentially break the circuit to the fuel feeding mechanism and thereafter to the air feeding mechanism.

4. An automatic control for heating systems tric motor at regular intervals of time, a plurality of cams on. said controller, a separate switch mechanism controlled by each cam, said cams being arranged to operate said switch mechanisms in sequential order, separate electric connecting means adapted to be connected to the individual electrically operated mechanisms of a heating system, said separate connecting means being connected with the individual cam controlposition and to deenergize the circuits to the separate electric connecting means in the reverse sequential order to their initial energizing,

5. An automatic control for heating systems having a plurality of electrically operated mechanisms subject to the initial control of a room thermostat responsive to temperature requirements, said control comprising a normally idle controller, an initiator circuit including an electric motor means for operating the controller, said initiator circuit adapted to be closed to respond to room temperature requirements for initiating operation of the motor and controller, a plurality of cams on said controller, a separate switch mechanism controlled by each cam, said cams being arranged to operate said switch mechanisms in sequential order, separate electric connecting means adapted to be connected to the individual electrically operated mechanisms of a heating system, one of said switch mechanisms being two-way and arranged to halt operation of the controller motor to insure operation of the same heating system during such time as room temperature requirements are unsatisfied, and means under control of the initiator circuit for operating the motor to reset the controller to its normal idle position and to 1 deenergize' the circuits to the separate electric connecting means in the reverse sequential order to their initial energizing.

6. An automatic control for heating systems having a plurality of electrically operated mechanisms subject to the initial control of a .room

thermostat responsive to temperature requirements, said control comprising a normally idle controller, an initiator circuit including an electrically operated mechanism of the same heat-- ing system, said cams being arranged to operate said switches in sequential order for independent sequential control of the individual electrically operated mechanisms of the same heating system, said double pole switch being arranged to halt' operation of the controller motor upon contact with the other pole thereof to insure operation of the same heating system during such times as room temperature requirements are unsatisfied, and means under control of the initiator circuit for operating the motor to reset the motor to its normal idle position and to reverse the position of said cam controlled switches.

'7. An automatic control for heating systems of the type having a plurality of electrically operated mechanisms subject to the initial control of a room thermostat responsive to temperature requirements, said control comprising a normally idle controller having a predetermined normal idle position of rest, an initiator circuit including an electric motor for operating the controller and a switch, a relay for operating said switch and adapted to be connected to a room thermostat and to be energized in response to room temperature requirements, said controller including a plurality of cams, a switch mechanism controlled by one of said cams and adapted to be connected to an electrically operated mechanism ofa heating system, a two-way switch mechanism controlled by another of said cams, and adapted to have one of its contacts connected to a separate electrically operated mechanism of the same heating system and the other contact of said two-way switch being connected to said relay operated switch, said cams being WILLIAM F. MILLER,

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