US2665071A

US2665071A - Stoker apparatus

Info

Publication number: US2665071A
Application number: US126962A
Authority: US
Inventors: Delmond L Getz; Edward C Lafferty
Original assignee: STEEL PRODUCTS ENG CO
Current assignee: STEEL PRODUCTS ENG CO; STEEL PRODUCTS ENGINEERING Co
Priority date: 1949-11-14
Filing date: 1949-11-14
Publication date: 1954-01-05
Anticipated expiration: 1971-01-05

Description

Jan. 5, 1954 D. l.. GE-rz x-:T AL 2,665,071

STOKER APPARATUS Filed Nov. 14, 1949 4 Sheets-Sheetll Fl-l lullll 65 67 70 mmm- @M 3.9%

ATTORN EYS Jan. 5, 1954 D. l.. GETz ET AL 2,665,071

STOKER APPARATUS Filed Nov. 14, 1949 4 Sheets-Sheet 2 L g8 .85 s 82 C /l' a 6 8 7L mmm@ ATTOR N EYS Jan. 5, 1954 D. L. GETZ ET AL STOKER APPARATUS Filed NOV. 14, 1949 4 Sheets-Sheet 5 I8 1E 8O I 18 17 m v l/f;

ATTORNEYS Jan. 5, 1954 D. 1 GETZ ET Al.

STOKER APPARATUS 4 Sheets-Sheet 4 Filed Nov. 14, 1949 ATTORNEYS Patented Jan. 5, 1954 attach STOKER APPARATUS Delmond L. Getz and Edward C. Lafferty, Springeld, Ohio, assignors to The Steel Products Engineering Company, Springfield, Ohio, a corporation of Ohio Application November 14, 1949, Serial No. 126,962

8 Claims.

This invention relates to stokers and more particularly to a modulating type stoker system.

In the ordinary installation of a stoker, particularly the type employed in household heating plants and the like, it is customary to employ a thermostat or other heat sensitive element which controls the operation of the stoker so that it is either on, when the temperature to be controlled is below the desired value, or off when the temperature is above such value. While such controls are satisfactory from the standpoint of maintaining desired temperature conditions, it has been found that such a system is open to objection from the standpoint of smoking conditions, the smoking usually occurring upon the shutting down of the supply of fuel, because there is a concurrent stoppage in the supply of combustion air from the blower, such sudden shutoff frequently producing smoking.

In accordance with the present invention a heat sensitive control is'provided which maybe actuated either by the temperature in the space to be controlled, or by the pressure, as in a boiler forexample, and which is of such character that it has a range of positions, varying from a high to a low demand for heat, as distinguished from a mere on and off position. This modulating control element is then associated with a stoker system incorporating a fuel and an air supp-ly means in such manner that both the rate of supply of fuel and of the air are Varied or modulated in accordance with the position of the heat sensitive control. Thus under cold weather conditions where a high rate of heat supply is necessary, the system produces a rate of operation of the fuel supply means which is correspondingly high. This is accompanied by a proportionate increase in the rate of introduction of combustion air. A's the demand for heat becomes less, the control modulates the action of the supply system, reducing, but without terminating, the rate of introduction of fuel and thereby maintaining a desired temperature condition with such lesser heat input. Concurrently the supply of air is reduced to the proper level corresponding with the reduced rate of fuel supply.

Normally this modulating control continues to function, the thermostat or heat responsive element providing for either increasing or decreasing the correlated rates of fuel and air supply, but without actually terminating such supplies, and hence effectively producing or eliminating the smoke condition referred to above and providing improved overall combustion, maintaining a more uniform depth of fuel bed, and resulting in higher overall efficiency.

The stoker system preferably employedis one which operates on an intermittent basis, and this in turn is controlled by a cyclic time control member with the fuel being supplied intermittently for a greater or lesser part of each cycle of the device. Thus when the demand for heat is the greatest, the control may produce such feeding operation of the fuel substantially throughout the entire portion of the cycle; as the demand for heat decreases, the portion of the cycle during which the fuel supply continues is progressively reduced to a minimum, which minimum however is sufficient to keep the furnace in operation on a standby basis, thus assuring that it will be ready and in condition for a higher rate of operation whenever desired and without the complete shut down of fuel and air supply which had led to the undesirable conditions described above.

There is also preferably provided a manual controlwhich can be used to override the automatic action of the system and to provide for terminatingthe fuel supply while continuing the flow of combustion air, when for example it is desired to allow all of the fuel in the furnace to burn out, either for shutting down the furnace, or for the necessary removal of clnkers, or the like.

It is accordingly the object of this invention to provide such a stoker system which is responsive to a heat condition to be maintained and which modulates the supply of fuel and air in correlated relation to each other and in accordance with the requirements for heat, while maintaining a continuity of operation and avoiding the objectionable smoking and other conditions associated with an abrupt and complete stopping of the operation.

Other objects and advantages will be apparent from the following description, the accompanying drawings and the appended claims.

Referring to the drawings- Fig. l is a view in elevation with certain parts being broken away showing a stoker constructed in accordance with the present invention;

Fig. 2 is a view of the stoker at right angles to the showing in Fig. 1;

Fig. 3 isa detail view partly in section showing the damper control for regulating thesupply of air;

Fig. e is a schematic layout in perspective showing the drive and control system in accordance with the present invention;

5 is a view in vertical section through the gear casing of the device on the line 5-5 of iig'. 6 Vwith parts shown in elevation;

Figs. 6, 7 and 8 are vertical sectional views on the lines i-, 'i-l and S--S of Fig, 5,1espectively;

3 Figs. 9, 10 and 11 are sectional views on the lines 9-S, El-I and Ii-II of Fig. 8, re-

spectively 12 is a view on an enlarged scale through the drive shaft of the stoker showing details of the control mechanism; and

13 is a vertical detail sectional View through the manual control for positively terminating the operation of the Stoker.

Referring to the drawings which disclose a preferred embodiment of the invention, the stoker is shown by way of illustration as having a main drive motor I serving as a source of power, which is enclosed within a casing II mounted upon the main gear casing I2. The motor has a drive pulley I 4 which carries V-belts i that drive pulley I6 on the main driven shaft I'! suitably journaled in casing l2 on antifriction bearings I 8. The shaft i1 extends through the gear casing and on its opposite end is directly connected to the rotor of a sirocco type blower which operates in blower housing 22. The blower inlet is shown at 23 and is provided with a series of vanes 25 which are mounted for rotation on individual shafts 25 between relatively closed and open positions thus effectively throttling the inlet to the blower and providing for regulating the amount of combustion air.

The control responsive t0 the heat condition to be maintained is shown diagrammatically at S0 in Fig. fl and is of suitable type to provide the desired modulating control, such as a Variable electrical current flow, depending upon the heat condition to be maintained. Such control is electrically connected as shown at 3! to an actuator 32 which is supplied with low voltage current by transformer 33 from power lines 34. The actuator is arranged so that its control shaft S5 rotates and thus rocks the sector 36 from one angular position to another, corresponding to the operation of control 30. In the arrangement illustrated in Fig. 4, the sector 36 is arranged to rotate in a clockwise direction in response to an increasing demand for heat. A suitable modulating control i and actuator 3| for use in the present system is a Minneapolis-Honeywell L-91 control with M904E Modutrol motor.

Connections are made from this actuator 32 to regulate both the air supply and the fuel supply an-d such supplies are varied in correlated reation with each other. Referring first to the mechanism for regulating the supply of air, a rod iii is connected to a suitable point on sector 36 and at its opposite end to the lever 42, a series of apertures being formed in the lever in which the .fr

rod may be selectively positioned to secure a different amount of movement, depending upon the particular adjustment desired. Lever 42 is fixed to a pivot pin d4 rotatably supported in the wall of the gear casing I2.

A second rod is also connected to lever 42 and at its upper end is pivotally connected to a crank 5i secured to shaft 52 rotatably mounted in bracket 53 which in turn is supported from the gear casing. The opposite end of shaft 52 is connected with a link 55 and this in turn operates through a link 55 to rotate crank 51 secured to shaft 58 rotatably supported in brackets 59. The opposite end of the shaft 58 carries a crank 5U connected to a link 5I which carries a lever 62 at its opposite end, lever G2 being connected to the shaft 25 of the damper in such manner that upon adjustment thereof, the damper will be caused to oscillate on the axis of shaft 2S between its open and closed positions.` It will thusr be evident that in response to operation of the actuating sector 3S, there will be a direct and corresponding adjustment in the setting of the damper, providing for opening the damper with increasing demand for heat and thus correlating the rate of air supply with the rate of fuel supply. It will be understood that the various linkages may be so adjusted as to obtain the precise movements of the damper for each setting of the actuator as desired to give a specific volume of air flow determined to be correct for that rate of fuel consumption.

The fuel is supplied to the combustion Zone by means of a suitable conveyor, and for purposes of illustration the invention will be described with reference to a stoker arrangement adapted to withdraw solid fuel from a bin and feed it into a retort, such as the arrangement shown in Scholl Patent No. 2,364,166, assigned to the same assignee as this application. In suoli a system one fuel conveyor tube such as 55 provides for withdrawing fuel from the bin, under the action of an internal worm conveyor indicated at GG, the fuel being transferred in a transfer chamber G' to a second fuel conveyor tube 68 having a similar conveyor worm 69 therein for feeding the fuel forwardly to the retort. The drive shafts of both conveyor worms 65 and 5S extend beyond the wall of the chamber *31 and on their overhanging ends carry drive sprockets l0. Chains II connect each sprocket I0 to driving sprockets 'I-l and are protected by covers I3, such driving sprockets being mounted upon opposite ends of the drive shaft "M, suitably journaled in the gear casing. Thus upon the rotation of such shaft 'I a corresponding and identical rotation of the two conveyor nights is produced, with consequent supply of the fuel from the bin, or other reservoir or fuel supply chamber as the case may be, forwardly and into the retort.

In order to provide for the desired intermittent but controlled operation of shaft i4 and the corresponding operation of the worms to supply the solid fuel, the mechanism in gear case i2 is provided as follows. Shaft I'I carries a worm 89 which drives the worm gear 82 loosely mounted on shaft 14. The gear has a laterally extending hub 82a which is pinned as shown at 83 to the hub 84 of a cam 85, the cam therefore rotating freely on shaft le, being directly driven from gear 82.

A follower in the form of a roller (il rides against the surface of cam 85 and is rotatably supported by a pair of rocker arms 8S suitably mounted on pivot shaft B journaled in the gear casing I2 by suitable antifriction bearings 9| (Fig. 9).

Shaft has an additional arm 93 extending radially therefrom and a cross pin 94 extends from the two arms 8S to arm furnishing a support for the connecting links 85 which are carried on pin 84 and held in proper spaced relation thereon by means of Cotter pins 96. A projecting pin 9i extends from the lower end of arm 93 and is formed to receive tension spring 98 which normally acts to swing shaft 95 about its axis and thus to maintain roller 8l in continuous riding contact against the surface of cam 85.

Connecting links 95 extend upwardly to a main feed pawl I which is rotatably mounted upon pivot pin II which in turn is carried by a pair of radius plates |62 loosely mounted on the hub of a main drive ratchet wheel IDE. The pawl is in such position that when it is moved in a counterclockwise direction (Figs. 7, 8 and 12) under the camming actionof the rockerarrn assembly, it will drive the ratchet 'wheel |05 also in'a'counterclockwise direction. The ratchet `wheel has Aan extended hub |86 through which `there extends a shear pin |07 forming a rupturable driving'connection with `shaft M. Thus rotation of the ratchet `wheel |65 `effects corresponding direct driving movement of vshaft M up tothe 'limiting strength of 'the `shear pin which is included for safety purposes. As'shown in Fig. 5 'the'shaft 'M is Vdirectly journaled at one `end in antifriction bearing `|03 carried'bycasing '52, and at Vits other end is supported. inslecve which in turn is gournaled in antifriction rbearing 'id carried by the casing. A retaining :pawl H19 pivotally mounted on pin I in the casing -I2 vand normally urged Itoward engaging position by weighted end |12 serves vto prevent backward rotation of ratche'twheel |05.

Atiming ratchet wheel i |1'5is mounted for -free Arotation on the hub |05 of the main ratchet |55 and `is arranged to be driven by a pawl H5 carried on the pin ||l`| fand hence movable lin corre sponding timed relation with the rocker arm 83 under the driving `action of the eain 135. retaining pawl is mounted on and al'A ranged opposite the teeth of pawl i |5 to prevent backward rotation thereof, such pawl being suitably weighted as shown at llt to bias it toward engaging position. Timing ratchet wheel H5 may thus operate independently of the main ratchet |d5, and is formed with an axially ezitending hub portion which is shaped as shown in Fig. B to define a series of cam steps |21A Preferably these steps progress from a minimum to a maximum and back to the minimum'position in a continuous series of relatively small increments.

Sleeve |33 has a projecting finger |40 fixed thereto which is arranged to engage pin |4| carried by interference arm |38 so that upon rotation `of sleeve |33, the interference arm will be raised to lift pawl Ill out of driving engagement with ratchet wheel |85, or lowered to establish and render such drive operable. A second finger |42 is likewise formed on sleeve |33 in `position to receive the pin lill when the interference arm is swung away to a clearance position, preventy ing excessive travel thereof.

When the interference arm |38 is in position to raise the main drive pawl, causing it to rock about its pivot shaft Il, such pawl is retained in the clearance position in which, notwithstanding the rocking Vmovement of `the Vrocker arm and-of 'the radius plates |2, it no longer has driving engagement vwith the teeth of the main drive ratchet |65. This prevents the transmissionof any driving power to the worm drive `shaft 14 as long as this condition exists. However in response to the lowering of the interference arm, the main drive pawl lill] is then allowed to engage the teeth of the drive ratchet |05, providing for establishing the driving connection to the worm drive shaft 1d.

The operation of the system takes place as follows. lWith the drive motor in operation, shaft is driven at a continuous and substantially constant rate of speed, and this in turn produces rotation of the main worm gear 82 and of cam 85. In response to rotation of cam 85, rocker arm 88 oscillatcs about its pivot shaft 90, and this in turn through the action of the connecting links produces a corresponding oscillatory movement of the radius plates l? and the pawl assemblies carried thereby. This includes the main drive pawl lill and the timing cam pawl IIB. Since there is no interference at any time with the driving action of pawl H6, such oscillatory movement produces a corresponding step by 'step advance in the rotation of the timing ratchet l5, and a similar or step-by-step movement of the timing cam 2| Under the action of the biasing spring |35 the sleeve |33 and its supporting nger |55 tend to be shifted in a. counterclockwise direction as shown in Fig. l2, with the result that the finger I 40 picks up the pin IM, and causes interference arm |38 to be lifted, thereby engaging the projection L|351 on pawl |90, raising it to and retaining it in its inoperative position. This interrupts or disables the drive to the worin operatlng shaft lll, but does not interfere with the cont1nuous step by step rotation of the timing cam. As the timing cam rotates, at some point in its rotation it will engage the roller |25, causing that roller to rise, thus rocking lever |25 about pivot |28, which in turn causes the motion to be transrn1tted through link |3| and lever |32, rocking lever |32 ina clockwise direction and thus overcoming the biasing action of spring |35. Such rotation of the sleeve results in the lowering of finger |49 and of interference arm |38, thus allowing the main drive pawl it to drop int@ driving relationship with the teeth ofn the main ratchet wheel |05, As long therefore as the cam engages roller |25, and thus retains the interference arm in withdrawn position, each successlve step of movement of the rocker arm SS will cause a corresponding driving engagement of the pawl with the ratchet IE5, producing a corresponding step of rotary movement in shaft 1li.

Y The particular point in the cycle of the timing cam at which the roller is engaged is determined by the setting of lever |27, and this in turn is controlled through operation of lever d2 and the positionmg ofthe sector 3G of the actuator. As the 'actuator changes its position in response to Vthe demand for heat, lever |27 is rotatably Vaddusted 'and'this produces a corresponding shiftmgm the 'position of roller |25, causing it te be engaged either earlier and thus for a greater portion'of the cycle, or later and thus for a lesser portion of the cycle of rotation of the timing cam. In .this way the number of strokes of advance movement of the worm drive shaft n'Ul `which occur during each Vtiming cvcle may be varied, va suitable `control providing twenty-one positions on the cam and thus making it possible to vary the rate 0f feed over a range varying from one step per revolution to twenty-one steps and hence substantially continuously throughout the operation of the system.

As the rate of fuel supply varies under control of the modulating control, the actuator 32, working through connections 4S, 42, 5S and the related linkage, provides for a corresponding adjustment in the setting of the vanes 25 and thus regulation of the supply of combustion air is maintained in completely correlated relation with the supply of fuel.

In some cases it is desirable to provide for manual control of the stoker in order to be able to shut oif the sup-ply of fuel completely while allowing,r the motor drive to continue for the purpose of supplying combustion air and thus completing the combustion of the fuel already in the retort. For this purpose the control illustrated in i3 is incorporated, and includes a manual control member ESQ in the form of a lever which carries a yieldable detent l5| to yieldably retain the arm in either the manual or automatic position. In the automatic position, the operation takes place in the manner already described. However when the handle is adjusted to the manual or off position, the shaft |31 is rotated within sleeve E33 and in so doing a nger |52 thereon is caused to engage beneath pin Ml, causing the lifting of the interference arm to a continuing interference position. Thus regardless of the position of roller I 25, which would otherwise lower the interference arm at some point in the timing cycle, the interference arm remains in its raised position, thus completely disabling the drive and preventing the rotation of shaft 14. Meanwhile the drive motor continues to operate and thus the blower continues to supply combustion air, allowing complete combustion of such fuel as remains upon the retort.

It will thus be seen that the invention provides a simple and highly satisfactory arrangement for continuous modulating control of the supply of fuel, providing for the intermittent operation of the fuel supply worms for a predetermined and variable portion of a timing cycle as required to bring about the proper rate of fuel supply. There is a corresponding operation and correlation of the rate of air supply from the blower so that proper modulated control of the air is likewise maintained, in order to establish and maintain the most efficient combustion conditions. The system thus assures the operation of the Stoker at such a rate as to maintain a predetermined heat condition, and with a continuously varying rate of supply to meet the demand. There is no abrupt change in operation such as an on and olf condition, and the objectionable smoking and inefficient combustion associated with such type of operation are effectively avoided.

While the form of apparatus herein described constitutes a preferred embodiment of the invention, it is to be understood that the invention is not limited to this precise form of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

1. A stoker system operable to provide a variable rate of fuel supply in a selected number of uniform feeding strokes of a fuel feeding member during an interval and under control of a modulating device responsive to a heat condition to be maintained, comprising a main drive ratchet connected to said fuel feeding member for operation thereof, a main drive pawl adapted for operating engagement with said main drive ratchet, means for continuously oscillating said main drive pawl to produce a series of uniform feeding strokes of said feeding member when said pawl is in engagement with said main drive ratchet, an interference arm for retaining said main drive pawl out of driving engagement with said main drive ratchet, a timing cam rotatable separately from said main drive ratchet and having a series of steps thereon ranging from a minimum to a maximum in small increments, means operated by said oscillatory means for producing uniform periodic advancing movements of said timing cam in response to each said oscillatory movement, a cam follower, means actuated by said modulating control for adjusting said follower in predetermined position relative to said cam to be engaged by a portion of said steps in the course of the revolution thereof, and linkage connecting said cam follower with said interference arm to cause said interference arm to be withdrawn allowing said main drive pawl to engage said main drive ratchet during the period that said cam follower is raised by the steps of said cam.

2. A stoker system as defined in. claim l in which the timing cam is advanced by a timing ratchet, and in which the means operated 'oy the oscillatory means for advancing the timing com includes an auxiliary pawl engaging timing ratchet.

3. A stecker system as defined in claim 2 in which the timing ratchet and the main drive ratchet are mounted coaxially with each other.

4. A stoker system as defined in claim 2 in which said main drive pawl and said auxiliary pawl are carried on the same oscillating means.

5. A stoker system as defined in claim l in which the steps on the timing cam are arranged in a series which increases and then decreases through a uniform series of increments.

6. A stoker system as delined in claim. l in which the interference arm is normally biased toward interfering position and is positively withdrawn in response to engagement of said cam follower with a step on said timing cam.

7. A stoker system as defined in claim l including means for regulating the air supply, and means operated by said modulating control for also actuating said air supply regulating means in coordinated relation therewith.

8. A stoker System as dened in claim including a manual control for terminating the supply of fuel by said feeding member while continuing the air supply.

DELMOND L. EDWARD C. LAFFERTY.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,335,008 Miner Mar. 3 i920 1,345,652 Tutein July '3, 1923 1,472,280 Ousdahl Oct. 3 0, 1923 1,520,922 Baker Dec. 3), 122A 2,145,942 McAdams Feb. 7, i539 2,354,517 Hallinan July 25, 1944 2,393,680 Hallinan Jan. 29, 1946 FOREIGN PATENTS Number Country Date 592,993 Great Britain Oct. 6, 191i?