US2348494A - Stoker - Google Patents

Description

-May 9,1944. f P, @E E S 2,348,494

s'romm Filed Sept. 23, 1940 2 Sheets-Sheet 2 52 flaw. 7

. I 2& I; ZT/ -j/ I d; J

35% j de/22x42? ten; v

Patented May 9; 1944 STOKER' Peter Paul Peters Waynesburg, Ohio Application September 23, 1940;Se'rial No. 357,961 1 Claim. (01. 110-109) This invention relates to stokers and more es-, pecially to stokers of the portable over-feed type intended for use in conjunction with the heating furnaces of homes and buildings.

An important object of my invention is to provide a stoker of the above character having a reciprocatingslide for feeding fuel into the fur,-

nace and poker bars extending longitudinally from theslide into the furnace so as to" agitate the bed of coals. therein, during the back-andforth movement of the slide.

Another object of my invention is to provide in a stoker ofthe above character, control means for automatically starting and stopping the operation of the ,stoker in response to temperature conditions within the enclosure to be heated, the

' control means being so constructed and arranged to arrest movement of the slide in or adjacent its fully retracted position with the poker bars partially or fully withdrawn from the fuel bed.

Still another object of my invention, is to provide a portable stoker. of the above character which is simple in construction and efficient in operation, and especially adapted to maintain the proper condition of the fire bed so as to obtain manner in which it is associated with a furnace;

Figure 2 is a transverse cross-sectional view through the lower end of the feed chute where it enters the furnace;

Figure 3 is a plan view of the stoker of Fig. 1;

Figure 4 is a detail plan view of the framesupporting the upper end of the chute, with parts broken away for greater clearness;

Figure 5 is a transverse cross-sectional view of the upper end of hte chute-supporting frame showing the Stoker control means in one position of operation;

Figure 6 is a side view taken at right angles to the view of Fig. 5; and V Figure 7 is an end, and injpart, cross-sectional view of-the chute supportingframe corresponding to that of Fig. 5,but'showing the'stoker control means in a different position of operation.

Referring to the drawings, in the cross-sectional view of Fig. 1 is illustrated a stoke'r of the overfeed type, this stoker being portable and of light construction so as to lend itself to usein connection with the heating furnaces of, private dwellings and buildings 1 This stoker comprises a vertically disposed hopper i having its top closed by a coverl and its lower end tapered downwardly and communieating through an outlet 0 with the upper end of a closed chute 3. This hopper is designed to 'contain a supply of coal. Thelowe'r endofthe chute projects throughthe entrance 4 of a furnace F and is enclosed by an air box 5 serving as a shield to close the lower part of theentrance but permitting the circulation of 'air around thejchute to cool the same. The lower edge of a vertically slidable door 42 upon the furnace is adapted to abut the flat horizontal wall of the air b0); 5.

The chute 3 is of rectangular cross section and to its side walls are secured angle irons 6" which extend lengthwise of the chute and project beyond it upper end and are fastened to the up,- right side walls of'a trough-shaped shelf 1. Closing one end of the shelf is a vertical plate lb which has its opposite side edges rolled into'circular shape to form sleeves to slidably' receive the upper ends of cylindrical legs 8. The shelf Tl may be raised or lowered to vary the inclination of the chuteby releasing wing nuts! 3, which serve to contract the sleeves 'lc about makes, and adjusting the shelf therealong, Bracemeinbers 9, comprising short angle sections; extend between and are attached to the plate lb and a shoulder piece Ill upon the lower face of the 'chute. The bottom of the chute below the hopper outlet c is closed bya plate ll removably connected to the angle irons 6' by wing bolts I 2. By

removing the plate l l coal may be emptied from the hopper. Rollers 14 are mounted adjacent the lower ends of the legs 8, and these rollers may be brought into engagement with the floor, by simply tipping the apparatus, to facilitate the handling of the stoker to and from the furnace.

Adapted to slide back and forth within the upper end of the chute in the vicinity of the hopper outlet c is a hollow rectangular slide [5, having aforward pushing face liq disposed perpendibular to the trough and'a fiat closure face 15b adapted to travel crosswise below the outlet 0 and intermittently open and elose this passage and allow coal to periodically flow therethrough into the chute in front of the slide. A pair of poker bars l5 having one of their ends fitted into sockets in the wardly along the bottom of the chute and extend intothe furnace. Theopera'ting" ends .of these poker bars arenpointe'd and serve, upon backward and forward movement of the slide, to

P ing fa e a p qjle'ct f ragitate the coal and break up coking therein so as to insure complete combustion of the fuel. Extending upwardly from the closure face l5b are agitator pins 36 adapted by the motion of the slide to rake through the bottom of the body of coal contained in the hopper l and tickle it down through the outlet 0. These agitator pins are removable, from the slide and may be used only when the coal is wet and tends to clog the outlet.

The size of the outlet 0 may be varied by means of an adjustable feed plate 31. By releasing wing nut 38, which engages a bolt 38a projecting up provides a fulcrum pin for a bell-crank lever 29, one arm of which lever projects upwardly and is adapted in one of its positions to engage a vertical shoulder b upon the rocker arm 35. The cam disk 34 upon its circumference is formed with a lobe a which during rotation of the cam disk is designed to ride against a bearing block 5| on the rocker arm 35 and tilt the latter, together with the mercury contact switch, upwardly about the fulcrum pin 26.

Pivotally connected to the other arm of the bellcrank trip lever 29 is the lower end of a ver tically disposed operating rod 52. This operating from the feed plate through a slot suitably formed in a bracket 39 extending laterally from the base of the hopper, the feed plate 31 may be shifted transversely across the outlet c to determine the I leaves'a'spacebetwee'n the pushing face l5a and the opposed lower edge of the hopper. This clearance is sufficient to avoidsqueezing small lumps of coal together so asto hinder theslide on its forward stroke; The teeth 31a and 31b operate to break through a conglomeration of coal packed between the slide and hopper. f 1

@Th'eisjlideis reciprocated within the chute as -follows: Pivotally connected at oneend to a cross- Lrod Ila Withinjthe hollow slide I5, is a connecting rod l I (Fig. 4) the opposite end of the connecting 'rod being forked to provide branches 20 and 23a. Branch 20 ispivotally connectedto a crank pin 2| secured upon the outer enact a crank 51, while branch 20a is pivotally connected to acrank pin22 arranged upon a generally circular cam disk 34. Both the crank 51 and the cam disk 34 are fastenedto a hub43 upon which is mounted a worm wheel 44 driven by a worm 45 (see Fig. 5),

the wormand worm wheel being enclosed within a gear housing I8 to which the end of bracket 39 is pivotally attached. The worm is secured to a rotary worm shaft 45'which extends outwardly through the gear case and has fastened upon its exterior end 'a pulley 41 (Figs. 6 and 7). A drive belt 48 winds over the pulley 41 and also over another pulley 49 secured to the armature shaft 50 of an electric motor IS. The motor I9 is suspended from the lower faceof the shelf 1 and .serves as the driving means for the slide l5.

Control means are provided for starting and stopping the operation of the stoker in accordance with the temperature of the enclosure to be heated and to bring the slide to rest in retracted position with the poker bars I6 withdrawn from the fire bed. These control means comprise a timing box'23 supported upon a saddle 24 fastened upon I the .top of 'thegear case [8 and disposed crosswise 'thereof. The ends of the saddle project beyond the'sides of the timing box, the end of the saddle Iupfon the'same' sideofthe gear-case as the cam positeside'ofthe gear case from the cam disk 34 'rod extends loosely through the bottom of the timing box 23 and connects with a wafer type thermostat 21 above the floor of the timing box. Extending centrally upwardly from the top of the 1 wafer thermostat and through the roof of the timing box is a stem 52a, this stem being threaded to receive an adjusting nut 33 upon its end exterior of the timing box. A coil spring 32 surrounds the stem 52a and is normally under slight in the pit P below the grate.

compression so as to exert a thrust between the top of the wafer thermostat and the roof of the timing box. f

The spring 32 serves as a cushion against which the thermostat is free to expand when the trip lever 29 is locked against rotation by the shoulder b on the rocker arm30. V

Immediately below the wafer thermostat is an electrical resistance element 28, one end of this element being connected to a conductor 35 forming one of the leads of an electric circuit, and the other'end of the element being connected, through a short conductor 35a to one of the terminals of the mercury contact switch 3|. Connecting the other terminal of the mercury contact switch with a terminal of the motor I9 is a conductor 35b. The other terminal of the motor is connected to a lead 350 constituting the lead of the electric cirboth the resistance element 28 and'the motor l9,

s0 that opening and closing the mercury contact switch cuts out andin the resistance and motor.

The timing box 23 not sealed against the atmosphere but on the contrary is provided with sufficient openings to permit the circulation of air therethrough so that the thermostat 21 may be responsive to temperature conditions within the enclosure to be heated by the stoker, as will later be explained.

Customarily associated withthe' furnace F is a shaker lever 4| pivoted adjacent its lower end and connected with the grate or the furnacein such a manner that by moving the lever backand forth the fire bed is agitated and the ashes are deposited In order to automatically actuatethe grate from the stoker so that the ashes will not accumulate in the fire box of the furnace, a link 53 (Figs. l and 2) is connected at one of its ends to a lug 54 projecting from the slide [5, and at its other end to one arm of a bell-crank 4|] pivoted at 55 to a-Wing 55 projecting laterally from the chute 3 (see Figs. 1 and 3). The other end of the bell-crank isswiveledto the upper end of the shaker lever 4| so that in' the forward and backward movement of the leveris rocked in opposite ate as follows: With the mercury contact switch closed, (Fig. 5) the motor 19 will rotate pulley 49,and through'belt 48 drive pulley 41 on worm impart rotation to worm wheel 44 and the latter will rotate both cam disk 34 and crank 51. Connecting rod ll having one of its ends connected to the cam disk and crank and its other end connected to slide l5 will impart reciprocating motion to the slide. The agitatoripins 36 fastened to the closure face l5b of the slide will rake across'the bottom of the mass of coal contained within the hopper I and coax it down through the outlet where it will be impelled by the pushing face [a of the slide down the chute into the furnace.

During the back and forth movement of the slide the poker bars IE will alternately penetrate andwithdraw from the fuel bed so as to break up coking and maintain the bed in a loose condition so as to promote complete combustion of The stoker will operate intermittently under.

the influence of the thermostat 21. With the control mechanism in the on position shown in Fig. 5 with the rocker arm 30 inclined downwardly in a left-hand direction, the mercury contact switch will be closed so that the resistance element 28 and the motor I9 willbe in circuit with the conductors 35 and 350. In this position the motor will be driving the slide l5 so as to feed fuel into the furnace F and the, resistance element 28 will be heating up the atmosphere within the timing box 28.

As the temperature within the timing box rises the wafer thermostat 21 will begin to expand. Since at this time an arm of the bell-crank trip lever 29 is latched behind the shoulder b of the rocker arm, the expansion of the thermostat will be in an upward direction against the coil spring 32. However, as soonas the lobe a on cam wheel 34 rides into contact with the bearing block 5! on the rocker arm, the latter will swing upwardly to release the trip lever from the shoulder. Under the urge of coil spring 32, the trip lever will snap anticlockwise into the position shown in Fig. 7 with the latching arm immediately below the end of the rocker arm, and the mercury contact switch will be simultaneously tilted downwardly in a, right-hand direction to open the motor circuit, cutting out the resistance element 28, and arresting operation of the stoker. Except for the short drift of the cam disk 34 after power has been cut off, the slide will come to rest in approximately its fully retracted position with the poker bars 16 withdrawn from the fire bed, which is essential in order to prevent damage to these bars by the intense heat of the fire.

Thereupon the heated air within the timing box 23 will slowly escape to the outside atmosphere, and the thermostat 21 will begin to slowly cool and contract. Such contraction draws the operating rodliZ upwardly, swinging the trip lever 29 clockwise so that the trip lever will drop behind the shoulder b, as illustrated in Fig. 5. rocker arm is thus again tilted downwardly in a left-hand direction so as to close the electric The circuit to start motor I!) and heat resistance element 28. The stoker continues to operate as before described until the rocker arm is again released by the cam disk, and this intermittent operation continues indefinitely so as to maintain a substantially even temperature within the enclosure to be heated.

The purpose of the resistance element 28 is to heat the small space within the timing box. While the stoker is in operation the expansion of the thermostat is hastened, but the time required for the heated air to escape from the timing box after the motor has been cut out delays the contraction of the thermostat, so that the periods of rest between successive operations of the stoker are thereby lengthened. By turning the adjusting nut 33 on the stem 52a, the position of trip lever 29 is changed, and hence the setting of'the control to respond to different temperature conditions may be varied.

When the stoker is in normal operation with the motor I9 driving the slide !5, the cam 34 will. make one or more revolutions, and at each revolution the lobe a. will engage the rocker arm to tilt the mercury contact switch 31 to open position. However, the drift of the cam is such as to carry the lobe beyond the rocker arm in a few seconds so that the rocker arm is again lowered to close the switch. That is, unless the rocker arm is maintained raised by the trip lever, the momentary raising of this rocker arm is insufiicient to halt the operation of the motor.

From the foregoing description it will be apparent that I have provided a stoker which during its operation pokes the fire bed of the furnace to break up coking which would interfere with the efficient combustion of the fuel and which at the same time shakes the grate to remove ashes from the fire not. a particular advantage of my apparatus residing in the provision of novel control means adapted to periodically actuate the stoker and to arrest its operation with the poker bars withdrawn from the fire bed. Instead of the mercury contact switch 3!, any other suitable form of switch might be employed. Manifestly various other changes in detail and design might be made within the scope of the accompanying claim without departing from the spirit of my invention.

I claim:

An overfeed type of stoker comprising a vertically-disposed coal hopper, an inclined chute located below the hopper and adapted to have its lower end extended through the door of a furace. an outlet for coal communicating between the bottom of the hopper and the chute, a slide reciprocable within the chute below said outlet, means-for reciprocating the slide for pushing coal down the chute, a plurality of elongated,

Images