US 2058945 A
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Oct. 27, 1936. c. R. BARNETT FURNACE CONTROL Filed Dec. 27, 1933 3 vSheets-Sheet 1 FigJ Fig.2
INVENTOR fiar/esRBame/t :ms pawn/wk ATTORNEY Oct. 27, 1936.
C. R; BARNETT FURNACE CONTROL Filed Dec. 27, 1953 3 Sheets-Sheet 2 Ann INVENTOR Charles R. Barneff 0a. 27, 1936. R ARNETT 2,058,945
FURNACE CONTROL Filed Dec. 27, 1953 5 Sheets-Sheet 3 l I Magnefic Swift/1 30 k9 I Mafor )8 INVENTOR Char/es RBa/"neff. Fly. 5 BY ATTORNEY Patented Oct. 27, 1936 PATENT OFFICE 2,058,945 rumvacn comor.
' Charles R. Barnett, Vineyard Harem. Masa; Stephen G. Luce, Jr., Tisbury, Masa, executor 'otsaid Charles R. Barnett, deceased Application December 27, 1933, Serial No. 704,127 9 Claims. (01. 110-32) My invention relates to improvements in combustion apparatus such as coal-burning furnaces. The principal object of the invention is to provide an improved automatic operating and control system for such coal-burning furnaces or boilers, and more particularly as applied to existing types of furnaces or boilers.
A further object is to provide light-actuated means by which the system is controlled, to give simplicity and improved economy of fuel and electric current.
Other objects will appear in the following description.
Referring to the drawings:
Fig. 1 is a diagrammatic view of my system applied to a coal-burning boiler ofknown type;
Fig. 1a. is a fragmentary view of the system shown in Fig. 1, one of the elements of the system being illustrated in detail.
, Fig. 2 .is a fragmentary section of the grate operating mechanism, ash pit, and light-sensitive control device;
Fig. 3 is a detail view of the shaker eccentric mechanism;
Fig. i is a vertical section of the friction drive coupling; and v Fig. 5 is a diagrammatic view of an alternative form of the system shown in Fig. l.
The numeral it denotes an automatic fuel feed coal-burning boiler of known type, having a fuel hopper H from which fuel descends by gravity through a funnel it to a pair of sloping grates it and it, when the latter are shaken. The
levers 22 of the grates l3 and M. Forks t3,
fastened to the shaker levers 22 by any suitable means, such as set screws 2t, engage grooved sleeves 2t rotatably mounted in the eccentrics 2B.
The numeral 26, Fig. 2, denotes a typical unit of the grate it, the unit it having a downwardly extending lever 21! and a rocker pin or axis 28. 'A bar 29 pivoted to all levers Z'i is articulated to the shaker lever 22 at the front of the furnace it, this internal shaker mechanism being old and well-known.
The numeral 30 denotes an electric 1110i 1r adapted to drive the shaft I9 through a worm a id gear speed-reducer 3|, or other suitable means, and a safety coupling 32. p
Referring to Fig. 4, the numeral 33 denotes [a driving cup fixed to the driven shaft 34 01 the speed-reducer 3|.
A driven flange 35 is fastened to the shaft |9. A presser ring 38 slidable in the. cup 33 is urged into the latter by springs 34a under adjusting nuts 36, gripping the driven flange 35 between a pair of friction rings 31 and Referring again to Fig. 1, the numeral 39 denotes a relay of well-known form, adapted to be controlled by the light-sensitive device l8 through an amplifier i8a. A magnetic switch 40, preferl0 8| by a bi-metallic thermal element 82 anchored 20 at 83. In its normal, or restrained position, switch 80 establishes'a circuit through conductor M to a' solenoid 85, thence to the positive terminal of the source of electrical energy 4| through conductor t'll. Thus a circuit is completed from the negative terminal of the power source 4 through time clock it, conductor 46, relay 3t, conductor 42, magnetic switch it, and finally to positive terminal ti. When a circuit is thus established, solenoid 85 operates plunger 86, and link Bl, to close switch it against the action of spring 89 thereby making 'a circuit to motor 30 through conductors it and M. A heating coil 90 underlying the thermal' element 82 will be seen to be connected in series relation with switch 88 and the conductors t8 and 39 to motor 30.
The timing mechanism of the clock it may be of the well-known electrically operated type, such as are shown in U. S. patents to Warren, #1,262,575; #1,522,988; or #1,533,67'7. A supply circuit 35 is provided to run the clock; and the clock is provided with the usual devices for tuming on and oh the control'circuit to conductor it at any desired times and intervals.
The operation of the device as shown in Fig. 1 is as follows: At a predetermined time in the morning, the clock 43 closes the circuit to conductor 46, the relay 39 being in closed position. The switch element 88 of the magnetic switch W is thereby closed, thus starting the motor 38 by the current from the main line 4|, and revolving the shaft I9. 'The eccentrics 2|, through the sleeves 25, oscillate the forks 23 and the levers 22, thereby reciprocating the bars 29 and rocking the grate units 26. This causes the ashes to drop into the ash pit l5, fresh coal descending from the hopper II. The shaking action normally continues until'live coals dropinto the pit. When this occurs, the light-sensitive device '18 isenergized, causing it to open the relay :9,
and thereby break the control circuit 46. This causes the magnetic switch 40 to break the main circuit 4|, thus stopping the motor 30, and stopping the grate-shaking action.
To provide for the contingency that live coals might not appear within a given time (as would When the fire has been shaken until live coals appear in the pit, the circuit is then held open by the light-sensitive device l8 so long as the glow remains. As soon as the glow ceases, or dies down enough to permit the device |8 to stop functioning, the relay 39 again closes. Therefore if the circuit at the time clock is still closed, the shaking will begin again, to continue until new live coals operate the device l8 to stop the shaking.
But if meantime the elapsed time is such that the time clock has now reached its circuit-opening position, then the shaking action cannot begin again until the clock reaches a new, predetermined time-point, at which time the clock is set for a renewed making of the circuit for grateshaking purposes. Thus, this setting of the circuit making and breaking devices in the clock 43 may be predetermined at whatever proves to be the suitable periods for use.
In case a grate should stick, tending to stall the motor 30, the flange 35, (Fig. 4), slips between the friction rings 31 and "a, but the motor, of course, draws a heavier current than is normally required. If the stoppage or retarding efiect should be only momentary, the excess current is not maintained long enough to actuate the the thermal release and as soon as the'retarding force subsides.the friction surfaces once more grip the flange 35 and the shaking of the grate is resumed. If the stoppage continues, the safety coupling continues to slip and the motor 'continues to draw excessive current until the thermal protective device in the magnetic switch 40 comprising the heating coil 90, thermal element 82 and spring 8| heats up and opens the motor circuit, after which the obstacle is removed manually and the thermal device reset in the usual way. a
The drawings illustrate a boiler with two grates. Should it be desired to operate only one grate, the fork 23 may be removed from its lever 22 by loosening the screw 24.
While a particular kind of bofler and grate are illustrated, it should be understood that the illustrations are purely typical and the device can be applied to any desired furnace or boiler having a suitable shaker grate or grates.
Referring to Fig. 5, in which an alternative embodiment of the invention is disclosed, the time clock 43' will be understood to be identical in all respects with the clock 43 of Fig. 1, but is shown in greater detail to facilitate an under-.
standing of the operation of the system. Similarly, the magnetic switch 40' is preferably identical with the switch 4|] of Fig. l, but like the time clock 43' is illustrated in greater detail to more clearly disclose the operation of the system. The light sensitive cell ll, ampiifler ll'a and relay 39' will likewise be understood to be identical with the corresponding elements of Fig. 1. This to establish the circuit to the stoker operating motor at predetermined intervals, as is the case in the disclosure of Fig. 1, but it is anticipated that under some conditions of operation it may be desirable to intermittently make and break the circuit to the stoker driving motor during periods when the time clock functions to constantly operate the latter.
To this end, a time limit switch 50 is interposed in the circuit between the time clock 43' and the driving motor ll of the grates. As shown, the time limit switch 50 comprises a motor 5| arranged to rotate a gear 52 rigidly connected to a cam 53 which in turn is adapted to operate a switch arm 54, connected in series with relay 39.
Spring 54 normally tends to open a circuit from the time clock 43' through conductor 55, thence to relay 3! and magnetic'switch 40' to motor 30 thus preventing operation of the stoker. For a more complete description of the switch 50 reference may be had'to pages 66 to 68 of Machine Design, of June, 1930, published by the Johnson Publishing Company, Penton Building, Cleveland, Ohio.
Now considering the cooperative functions of time clock 43' and time limit switch Ell: The time clock is permanently connected to the source of electrical energy 4| by lead wires 45' to constantly operate the clock motor 60. The motor 6|l-rotate's a dial 6| provided with angularly adjustable, on and oil riders, 62 and 62a respectively. It will be understood that these riders may be positioned on dial 6| at any desired points corresponding with the particular hour or time when it is desired to complete or interrupt a circuit to motor 5| of time limit switch III, and thus effect intermittent operation of the stoker motor Ill. The riders 62 and E ic are arranged to contact a laterally protruding knobllb of a switch arm 63 which is maintained in on" and 01! positions by a spring actuated toggle 820. A mercury reservoir 64, rigidly connected to switch arm 63 is provided with electrodes as shown, to complete a circuit from power source 4| through conductors 65 and 66 to motor 5| when switch arm 63 occupies the position shown in Fig. 5. Ann 63 is rockedto the position of Fig. 5 by the on rider 62 and is adapted to be moved in a clockwise direction to its oif" position by rider 82a which cams the knob 62b downwardly as dial 6| rotates in a clockwise direction.
As will be apparent, the circuit from conductor 56 leads through switch 54 relay 39' and thence to .magnetic switch 40' through conductor Ill. Magnetic switch 40' is, as has been pointed out, identical with the switch 40 of Fig. 1a. Briefly, the conductor 10 is connected to a switch arm 18, which is normally restrained from movement under the influence of a spring I1, by a thermal element I6 one end of which is anchored to the base of magnetic switch 40'. When thus restrained, switch 18 establishes a circuit through conductor 12 to solenoid II and then back to the negative terminal of power source 4|. Thus solenoid 'll operates to close switch 13 thereby completing a circuit through heating element 1! to motor ll.
The time limit switch I! will operate to alternately make and break the circuit to motor 30' during any period of time when switch arm 83 of clock 43' is in its on" position. The duration of the operating and idle periods of the stoker motor may be modified by replacing the cam 53 with others otdiflering configuration. Cams of Total time cycle Circuit closed I 5 minutes 3 seconds to 3 minutes. 15 minutes 9 seconds to 9 minutes. 30 minutes 18 seconds to 18 minutes. 1 hour 36 seconds to 36 minutes.
By utilizing the time clock 43 for the main turning on of the circuit in the morning and turning ofi at night, the time limit switch 50 can be made use of for the shorter intervals of turning the' current on and oil", such as might be suitable for ensuring the proper shaking of the grate at such times as might be necessary.
- It will be noted that the. thermal overload de-' vices of magnetic switches 40 and 40' will be effective to break the circuit to the stoker motor in the event that the thermal elements 82 or 76 respectively are caused to move to the dotted line positions shown as a conseguence of overheating of the respective coils 80, or 15.
What is claimed is as follows:
1. In a furnace control, the combination with the shaker mechanism of a furnace, and an electric motor and circuit for operating the shaker mechanism, of an electric light-sensitive device located in proximity to the ash pit whereby to be actuated by the light from live coals, a control switch and circuit connected with the light-sensitive device for breaking the electric motor circuit, and a timing device controlling the electric motor circuit to make and break said circuit at selected intervals when the said control switch-is in circuit making position.
2. In a furnace control, the combination set forth in claim 1, having in addition thereto an auxiliary timing device operating an auxiliary switch in said electric motor circuitto make and break said circuit at shorter time intervals than the make and break periods of the first mentioned timing device.
3. In a furnace control, the combination with the shaker mechanism of the furnace, and an electric motor for operating the same, of a timeclock-controlled circuit for said motor including a time clock switch in said circuit, an'electrlc light-sensitive device located in proximity to the ash pit whereby to be acuated by the light from the live coals, a circuit for. said light-sensitive device including a relay mechanism; a switch opened by said relay and located in said time clock circuit; and switch opening and closing devices carried by said time clock and operating upon said time clock switch to open and close said time clock circuit and thereby stop and start said electric motor at predetermined times when the said relay switch is closed.
4. In a furnace control, the combination set forth in claim 1, and wherein the electric motor is connected to the shaker mechanism by a friction coupling, and the said circuit for said electric motor contains a thermal protective device to open said motor circuit when obstacles located in the shaker mechanism'prevent said' friction coupling from driving. v
5. The combination with a coal burning furnace including a grate, electrical means to actu ate said grate, an ashpit below the grate, and a source of electrical energy, of control .means to initiate and terminate operation of the grate actuating means comprising a. time sensitive switch connected to said source of energy in series with the grate actuator, a normally closed relay switch in series with said grate actuating means and time switch, and a light sensitive device focused in the ashpit and connected in series with the source'of energy, the time switch, and the actuator.
6. The combination with a coal burning furnace including a grate and an electrical actuator therefor, an ashpit below the grate and a source of electrical'energy, of control means to initiate and terminate operation of said grate comprising a time controlled switch connected in series with said source of energy and said actuator, a normally. closed relay switch in series with the actu ator and time switch,- and a photo electric cell focused in said ashpit and arranged to open said relay switch as an incident to the falling of live coals from said grate to the ashpit.
7. The combination with a coal burning furnace including a grate and an electrical actuator therefor, an ashpit below the grate and a source of electrical energy, of control means to initiate and terminate operation of said grate comprising a time controlled switch and a time limit switch arranged to jointly and individually control a flow of current from said source of energy to said actuator, a normally closed relay switch in series with the actuator and time switches, and a light sensitive cell focussed in said ashpit and arranged to open said relay switch as an incident to the falling of live coals from said grate to the ashpit, to defeat operation of said' first named switches.
8.'The combination with a furnace including a grate, an electrical actuator for said grate, and a source of electrical energy; of a time clock in fixed circuit relation with said source of energy, a time limit device, a switch arranged to be controlled by said clock to make and break a circuit from said source of energy to said time limit device, a switch arranged to be operated by said device to make and break a circuit from said source of energy through said first mentioned switch to said actuator, to cycle the latter at prea source of electrical energy; of a time clock in fixed circuit relation with said source of energy, a time limit device, a switch arranged to be controlled by said clock to make and break a circuit from said source of energy to'said time limit device, a switch arranged to be operated by said device to make and break a circuit. from said source of energy through said first mentioned switch to said actuator to cycle the latter at predetermined short intervals while the circuit from the first mentioned switch to said device is in circuit making position, and a light sensitive cell efiective to break the circuit from said source of energy through said first and last mentioned switches to said actuator, as an incident to the falling of live coals from said grate.
' C ARLES R. BARNETT.
(IERTIFICA'JLE 0F CORRECTION.
Patent No. 2,058,945. October 2'7, 1936.
CHARLES R. BARNETT.
It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, first column, line 9, for the hyphenated word "circuit-breaking" read circuitmaking; andthat the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.
Signed and sealed this 5th day of January, A. D. 1937.
Henry V'an Arsdale (Seal) Acting Commissioner of Patents.