US2154787A - Apparatus for detecting and maintaining fire in a stoker - Google Patents

Description

| R TEEPLE APPARATUS FOR DETECTING AND MAINTAINING FIRE IN A STOKER Filed June 18, 1955 I I I I I I I u w L. R .TEEPL "lllllmlllll April 18, 1939.

Patented Apr. 1 8, 1939 APPARATUS FOR DETECTlNG AND MAIN- TAINING FIRE IN A s'roKEa,

Lawrence It. Teeple, Portland, Oreg. Application June 18, 1935, Serial No. 27,275 6 cams. (01. 236-46) This invention relates generally to controls for stokers'and particularly to a method of and apparatus for detecting and maintaining fire in-a stoker. I M

This invention has a threefold purpose. The

first to shorten the'duration of or to suspend entirely the periodic refuelingoperation normally initiated by an intermittently operated switch-' ing mechanism in order to prevent the refueling 2 operation from overheatingthe house when the condition of the fire is good.

The second object is to permit the use of longer periods of refueling operation than are feasible with the use of fixed intermittent refueling set tings in order to make it possible to more adequately rekindle a poor fire without danger of I overheating the house.

The third object is to prevent the'stoker from operating when the tire is completely extinguished or too low to rekindle by finally stopping the -stoker if the combustion temperature fails,

to respond prior to the end of a period of time -measured from the beginning of eachstoker operation. I v

These and other objects are accomplished in the manner set forth in the following specification as illustrated in the accompanying drawing, in which:

Fig. 1 is a sectional view through the casing of the device showing a wiring diagram and associated controls in a condition when the stack. temperature is down but rising. I I

Fig. 2 is a view similar to Fig. 1 showing the stack temperature up and the stack, operated switch just. tripped. p l r Fig. 3 is similar to Fig. 2 showing a condition 1 in which the fire is out, the stack cold, and the stoker shut down.

Fig. 4 is a section taken Fig. 1.

parts throughout the several views.

Referring in detail to the drawing, there is shown a casing III which is provided with pillars ll forsupporting same upon a base l2, which is secured to a stack l3 or a combustion chamber in any convenient manner. Baflles I4 are provided on the pillars II to prevent an objectionable amount of heat from passing directly from the stack Hi to the casing l0. i

The base I2 also carries a tubular projection l5 which extends into the stack l3.; The projection I5 is provided with aclosed end It in which journals a rock shaft ll whose opposlte alon the line 4.4 i g n overthrow mechanism is well understood and will Similar numbers of reference refer to similar shaft [1. The purpose of this arrangement is to utilize a change'in the temperatureof the stack I3 t0 produce a rotative movementofthe shaft IL ,On'the shaft ,l'l issecured 'a cam 20 whose high portion 2| may be rotatably adjusted with relationto theshaft llv by means of a screw 22, which occupies a-curved slot 23 within the indicator plate 24; which is secured to the sha H by means of the screw 25.

The screw 22 extends'into the cam 20. The

plate 24 is provided with a .pointer 26, and the 'ment l9 whose opposite 'end'is secured to the 'cam 20 is-provided with graduations 21 in order thatthe proper relationship betweenthe" high portion 2| and the shaft I! may be obtained.

1 Mounted withinthec'asing Hlis a temperature responsive element 28; which is in the form of a strip, o'ne end'of which is secured by means of the clip 29 to thecasing l0. Near the element 28 is disposed a heating element30, same being preferably mountedon a slidable support 3| for the purpose of adjusting itsrelationship to the element 28, this relationship determining the .time required for theelemen-t 30 to move the element 28 to a tripping position.-

. Mounted on thebase 32 of insulating material is a pivot 33 on which is rockablymounted an arm 34. The arm 34 is provided with a projection 35, on the outer end of which is formed a notch which receives the fulcrum 31 of a pair of oppositely disposed contact arms 38 and 39,

which are urged to one extreme position or the other by means of a spring 40. This type of notbe elaborated upon here.

Also mounted within the casing I0 is a block 4| of insulating material on which is mounted a rocker arm 42 of insulating materiaLsaid arm being provided with shoulders 43 and 44. the former of which normally acts as a stop for the element 28 when cool and the latter acts as a stop for the strip 28 when it is deflected sufficiently by the action of heat from the heating element 30.

The arm 42 is urged toward the element 28 by means of a spring 45, which is secured to the lever 46 which projects from the arm 42. The pivot 41 of the arm 42 is fixed to the block 4|, and although the arm 42 is of insulating material, the end 48, through which the pivot 41 passes, is preferably of metal. Attached to the end 48 is a contact arm 49 which engages a contact post 50 on the block 4| when the element 28 engages the face 5| between the shoulders 43 and 44 of the arm 42. When the element 29 rests upon the shoulder 44, the arm 49 moves away from the post 50.

A manually operated release button 59 is provided on the casing III, the purpose of which is to make it possible to reset the arm 42 after it reaches the position shown in Fig. 3. This is brought about by a complete extinguishment of the fire and is determined by the operation of the stoker for a fixed period of time, after which, if there is not sufiicient heat developed, the stoker will be shut down finally or completely until it is manually reset through the operation of the button 53.

Associated with the arm 38 is a contact post 60, which is connected to one side of the heating element 30 by means of a wire SI, and associated with the arm 39 is a post 62, which is connected by means of a wire 63 to a point in the wire 51 between the thermostat 58 and the pressure regulator 59.

A timed interval switching mechanism 64 is interposed in the wire 63, and this may be of any of the well known forms of the device whose function it is to periodically close its portion of the motor circuit. The pivot 33 is connected by a wire 55 to a point in the lead 51 which is between the motor 54 and the thermostat 58. A lead 66 connects one side of the heating element 30 with the lead 56 of the motor circuit.

It must be understood that the temperature responsive element l9 may be either of the type which operates its switches at definite temperature settings or it may be a friction device tripping the switches on rises and falls of the temperature without regard for the exact value of the temperature. Also, the timing device may either be an electric heater 30 acting on the thermostatic element 28, or it'may be any of the several types of mechanical timing devices such as an electric clock motor.

The heat responsive element I9, which is exposed to stack temperature, serves a dual purpose. First, it shuts oil the timing device, which in this case is the heater 3!), after the stoker has operated a predetermined length of time and there has been completed an appreciable rise in the stack temperature. But if there has been an insufficient rise in the stack temperature after a period of stoker operation initiated by any instrument, the motor 54 will be stopped by the separation of the arm 49 and post 50, which also opens the circuit to the heater 30.

Due to the fact that the heating element 30 has caused the heat responsive element 28 to take the position shown in Fig. 3, which permits the arm 42 to move under the influence of the spring 45, the stoker motor 54 will now. be finally stopped and cannot be started from any action arising within the controls themselves but can only be started by the manual operation of the button 53, which will reset the arm 42 to the position shown in Figs. 1 and 2.

The second purpose of the element l 9 is accomplished when there is a desired rise in stack temperature before or during a period of stoker operation as caused by the element 64. This is a switching operation which governs the occurrences or length of the stoker refueling operation from element 64, which otherwise periodically starts and stops the stoker during periods when there are few calls for heat from the elements 58 and 59.

It will be understood that the sole purpose oi the element 94 is to maintain a lire during periods of inactivity. In other words, as long as there are few calls for heat from the elements 58 and 59, the element 64 serves to periodically operate the stoker a definite number of minutes; but when the stack temperature rises sufficiently to open the refueling high limit switch arm 99, the periodic timing device 54 is prevented from starting the stoker, or if it has already started a refueling operation, it will be stopped unless further operation is desired by the thermostat 59.

In order to explain the operation of this device, there is shown a stoker motor 54, which is connected to a power line 55 by means of a lead 56 and a lead 51 which passes through a room thermostat 59 and then through the post 59 and arm 49 to the pivot 41, thence through the pressure regulator 59 to the power line 55.

The operation of the device is as follows:

Assuming that the stoker has.been operated and that this operation has been followed by a period containing no calls for heat from the elements 58 and 59, during which time the temper- I ature of the stack'naturally falls, the periodic refueling switch 64 now functions, the parts being in the position shown in Fig. 1 except that the element 55 is holding open the circuit of the motor 54-. In this case, the closing of the circuit throughthe switch 54 permits a flow of current around the thermostat 58 through the arm 99, permitting the motor 54 to operate. At thesame time, current flows through the arm 99 to the heating element 90, causing the element 25 to be deflected at a rate dependent upon the positioning of the support 9|.

It will be noted that at the commencement of the operation, the element 29 rests upon the shoulder 43 of the arm 42. It can be seen that the heating element 30 serves as a timing device,

stoppage of the motor 54, rendering all of the controls inoperative until the device is manually reset by pushing the button 59. If, on the other hand, the temperature does rise within the stack, thereby causing the element H to rotate the cam 20 to the position shown in Fig. 2, then the flow of heat to the element 90 will be interrupted and the element 28 will not rise to the shoulder 44, thus preventing the arm 49 from being drawn away from the post 50 and the operation of the motor 54 stopped.

I claim:

1. An apparatus of the class described consisting ofa heat responsive element adapted to be inserted into a smoke stack, a switching mechanism operated by said heat responsive element, an' intermittently operated time controlled switching mechanism adapted to periodically operate a stoker, said temperature controlled switching mechanism serving to render the intermittent switching mechanism inoperative when the stack temperature rises above a predetermined minimum, a second time controlled switching mechanism controlled by said heat operated switching mechanism, said second time controlled switching mechanism serving to'render the entire controls inoperative whenever the stack temperature iails to rise to a predetermined minimum within the period of operation determined by said second mentioned timing device.

2. In a stoker control a stoker motor circuit. a room thermostat for controlling said circuit in accordance with room temperature requirements, a normally closed thermally controlled switch in said circuit, a heater for causing said switch to open after a predetermined period of time, a circuit for energizing said heater, a thermally controlled switch in said heater circuit,

said last named switch adapted to open the heater circuit in response to a predetermined heat of combustion of the stoker, whereby in the absence of heat of combustion the heater causes the stoker circuit switch to open after a predetermined period of time, and mechanical timing means for periodically closing said stoker I circuit and said heater circuit through said second named switch during mild weather when the room thermostat requires an open stoker circuit.

3- In a stoker control, a stoker motor circuit, a normally closed thermally released switch in said motor circuit, a heater which when energized is adapted to heat and thereby release said switch after a predetermined period of energization, a room thermostat adapted simultaneously to close said motor circuit and to energize said heater, a means responsive to the heat of combustion of the stoker for opening said heater circuit to prevent the opening of the normally closed switch while the stoker fire is burning normally, and timing means for operating the motor at intervals in mild weather during periods when the room thermostat is not in a motor circuit closing position whereby the fire is maintained.

4. In combination a stoker, a stoker control including a stoker circuit, a space thermostat connected to open and close said circuit to operate said stoker in accordance with the heat requirements of said space, a normally closed thermally controlled switch in said stoker circuit, a heater for causing said switch to open after a predetermined time lag, means for shunting said space thermostat at fixed intervals of time to operate the stoker when there is no call for heat and for operating said heater during said last mentioned motor operations, and a stack thermostat for simultaneously controlling said shunting means and said heater.

5. In a stoker control, a stoker motor circuit, a room thermostat for controlling said circuit in accordance with room temperature requirements,

said circuit, a heater for causing said switch to open after a predetermined period of time, a circuit completed by the room thermostat for energizing said heater, a thermally controlled switch in said heater circuit, said last named switch adapted to open the heater circuit in response to a predetermined heat of combustion of the stokerywhereby in the absence of heat of combustion the heater causes the stoker circuit switch to open after a predetermined period of time, and timing means operable at intervals during mild weather to close the motor circuit to maintain the stoker fire and at the same time to close the heater circuit whereby during periods when the room thermostat is inoperative the stoker motor is safely operated at intervals as long as a fire is maintained and is conclusively shut down if insuilicient heat is generated to operate said thermally controlled switch.

a normally closed thermally controlled switch in 6. In a stoker having in combination an electric motor, means comprising a first switch for connecting the motor to a source of power to operate the stoker in accordance with heat requirements, means including a second and third switch jointly operable for connecting the motor to the source at time intervals in the absence of heat requirements, a fourth switch for conclusively interrupting circuits to said first, second and third switches, a timing mechanism for opening the fourth switch a predetermined period after being initiated, means including a fifth switch for connecting the timing mechanism with second switches so that either of which upon closing to start the motor also initiates operation of the timing mechanism, whereby upon failure of a rise in stoker generated temperature within said predetermined period the fourth switch is opened to conclusively shut down the stoker.

LAWRENCE R. 'I'EEPLE.

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