US1480868A - Automatic stoker - Google Patents

Description

'IED'. STATESA PATEN WILLIAM C. STRIPE, 0F PITTSBURGH, PENNSYLVANIA.

.AUTOMATIC STOKER.

application med February 25, 1922. serial No. 539,109.

To aZZ whoml t may concern.'

Be it known that I, WILLIAM C. STRIPE,

a citizen of the United States, and a resident of Pittsburgh, county o f Allegheny, and State of Pennsylvania, have invented certain new and useful Improvements in Automatic Stokers, of which the following is a specification, reference being had to the accompanying drawing.

My invention relates more particularly to th-at class of automatic stokers in which coal is fed Jfrom a hopper into the path'of a reciprocating ram and forced by the latter through al throat into the `fire box of the furnace. In the Operation of devices of this character the forward or feeding movement of the ram is sometimes interrupted by the lodging of a hard lump of coal or some foreignbody such as a piece' of iron, stone or the like, between the forward end of the ram and the throat of the fire box; it has therefore been customary in the art to provide means intended to prevent damage to the stoking mechanism under these circumstances which might otherwise occur by reason of the continuous application oit' power without a corresponding movement @t the ram being possible; for example -a frangible pin or shearing member employed to operatively connect suitable parts of the mechanism which serves to actuate the ram; and adapted, in case the movement of the ram be obstructed, to break or shear and thus disconnect the ram from its actuating mechanism.. V

'it has been found, however, that it the pin be made of suiiicient strengthto transmit the drive to the ram at certain points-.in its path ot' movement, it will not shear if the movement o the ram be interrupted at other points and more particularly when it nears the end of the eed stroke and the connecting rod and crank of the actuating means are approaching alignment, so that under these conditions a dangerous strain may be placed on the actuating mechanism; on the other hand, if the pin be made light enough to shear under such conditions it will frequently be `unable to support the strain imposed on it in the normal operation of the mechanism especially when the of considerable respective angularity..

The principal object of my invention is the provision of means in an automatic Stoker of the general character aforesaid .Which are effective upon the movement of the ram being interrupted from any cause,

such as the lodgvment of a foreign body between the ram and the fire box throat to positively relieve the'ram actuating mechanism from undue strain irrespective of thc position of the ram.

A further object of the invention is the provision of means in an automatic stoker adapted, when the movement of the ram is interrupted toward the forward end of the feed stroke, to permit the crank and connecting rod of the actuating mechanism to pass over` the dead center while the ram remains stationary without shearing or rupturing any portion of the actuating mechanism or bringing an undue strain on any of the parts thereof.

invention further comprehends the E M emplbyment in combination in an automatic Stoker of a frangible pin or member adapted to shear if the movement of the ram be interrupted while the latter is at certain portions oi?Y its stroke and ot resilient means adapted to yield when the movement ot' the ram is interrupted at other portions of its stroke whereby, irrespective of the point at which the ram is blocked, the actuating mechanism is relieved from undue strain and the shearing of the pin under certain con,- ditions ci operation avoided.

The invention further includes all ot the other various objects and novel features ot construction and arrangement hereinafter more particularly specified or described.

For the purpose of enabling those skilled in the art to readily comprehend and practise the invention, l have somewhat diagrammatically illustrated in the accompany- Ingdwvlng and will now proceed to dcscribe a typical form of automatic Stoker embodying my invention, Fig. 1 being a side view partially in elevation and partially in vertical section of the stoker and a portion of the adjacent furnace, Fig. 2 a similar view with several of the parts in a different position, while Fig. 3 is a fragmentary rear end elevation of the ram and portions of the adjacent mechanism. Like numerals are used to designate similar parts in Ithe several gures. crank and connecting rod are in a position As illustrated, the mechanism comprises a fuel hopper 1 communicating through a throat or fuel passage 2 with a iirebox 3, a horizontally reciprocating ram 4: being arranged intront of the throat to travel in a suitable sleeve or casing 5, these parts being of an suitable construction. Means are provi ed for actuating the ram comprising a crank 7 of suitable throw conveniently integral with a crank shaft 8 rotatably journaled in suitable standards 9, 9', the crank being`connected with the ram through the medium of a two-partconnecting rod 10 comprising relatively movable conveniently telescopic parts 11 and 12, hereinafter more fully described, and adapted to oscillate on a wristpin 13 carried by the ram.

For rotating the crank shaft 8 suitable means are provided, conveniently comprising a worm gear wheel 15 carried by and normally rotative with the shaft andl arranged to mesh with a worm 16 on a transversely extending worm shaft 17 journaled in sultable supports. Rotatable with this shaft and secured thereto is another wormv wheel 19 arranged to mesh with a wo m20 on the main drive shaft 21 which is supported in suitable standards 22 and .actuated in any convenient way; as shown through a sprocket wheel 23 and chain 24 driven from.y any suitable source of power.

One of the portions of the two-part connecting' rod 10, conveniently the portion 12 which engages the wrist pin 13, is provided with a pre erably cylindrical longitudinal .recess 26 intowhich 'the end of the other part 11 of the connecting rod is adapted to form a good working fit' thus enabling relative longitudinal movement to take place ber tween the two parts of the rod. Means are provided for maintaining the parts of the rod in assembled relation which V-may also serve to limit the relativemovement therebetween, said means being conveniently in the form of a transversely extending pin 28 carried by the part 1:2 and extending through a suitable slot 29 in the part 11, engagement of thel pin with the ends of the slot of course limiting possible relative lon- 'tudinal movement of the parts. Between t e end of the part 11 and the bottom of the Y recess 26 is positioned a relatively heavy coil spring 30 which is so adjusted as to normally maintain the part 11 as far away from the wrist pin as it will go and as shown in Fig. l, the function and operation of this spring beinlg hereinafter more fully .de--V strength of this pin is such that during the normal operation of the mechanism it is effective to maintain the crank shaft in fixed relat1on but in case under certain conditions hereinafter de scribed, the movement of the ram is interrupted the pin will shear and allow the gear 15 to rotate freely on the shaft 8, thus permitting the latter with its connected parts to come to rest whilethe actuating mechanism for driving the gear wheel continues in motion.

In the normal operation of the machine with the parts constructed and assembled substantially as hereinabove described, the ram is slowlyI reciprocated, the coal feeding down from the hopper during the retraction or back stroke of the ram to be pushed into the tire box upon the forward or feed stroke. If, however, the forward stroke-of the ram is arrested when it is well toward the outer end of its stroke as in Fig. 1 through the lodging of a large obstruction in front of the ram, the shearing pin 32 in consequence of the continued application of power from the drive shaft, will shear olf and thus save the actuating mechanism from excessive strain. Under these conditions the spring 30 will normally remain extended or at most be only partially compressed prior to the shearing of the pin, as owing to the greatangularity between the crank and the connecting rod the longitudinal thrust ou the spring is relatively low while the shearing force exerted on the pinis relatively great. On the other hand, in case the motion of the ram is arrested near the end of the feed stroke as by the lodging of a relacrank and connecting rod to pass the deadv center and retract the ram without shearing the -frangible pin, for under these conditions the longitudinal thrust on the connecting rod, due to the slight angularity between it and the crank, is very great in comparison with the force which tends to shear the pin 32. Of course upon the retraction of the ram theobstruction O is free to fall to a position in which it will be forced into the fire box duringthe ensuing feed stroke.

It will thus be apparent that when the movement of the ram is blocked by a relatively small obstruction so that the longitudinal pressure on the spring is relatively great, thespring will be suiiiciently compressed to permit the crankand connecting rod to pass the dead center without excessive strain on the actuating mechanism and without in any way interruptlng the normaloperation of the machine, while when the ram is blocked at such point in its stroke ear wheel and Y ill that the force tending to shear the pin is relatively great,the pin will shear to relieve the actuating mechanism from excessive strain, in which case of course it becomes necessary to replace the pin before the ram can again be put into operation.

As in the practical operation of automatic stokers it is found thatvthe jamming of the ram is in the great majority of cases due to the presence of small foreign bodies in the coal as distinguished from bodies of relatively great size, it will be evident that a stoker embodying my invention may be kept in operation for a much greater proportion of the time than a stoker in which a frangible pin or other element must be replaced every time that the movement of the ram is blocked by any sort of obstruction, large or small, as with my improved construction the replacement of the frangi ble pin is only required in the relatively.

rare instances in which the stoppage of the ram occurs when there is considerablelrelative angularity between the crank and connecting rod, or in other words, when it is brought about by a relatively large obstruction.

F or the purpose of enabling those skilled in the art to comprehend and practise the invention, I have herein described and illustrated with considerable particularity a preferred embodiment of means suitable for attaining the objects thereof in connection with the Stoker having but a single ram, but it will of course be understood that stokers of this general class are ordinarily arranged in batteries each battery having a plurality of rams feeding a corresponding number of retorts and actuated from the same crankshaft and my invention is particularly suitable for use in such installations since the shearing of the frangible pin in the ordinary type of stoker under such conditions results in putting not only a single ram but the whole battery temporarily out of commission. Furthermore, I do not desire or intend by the foregoing description and accompanying drawing to in any manner limit myself to specific details of construction or arrangement of parts or to any definite position of the frangible pin or other shearing element in the actuating mechanism, as the same may be placed therein at any suitable point, and the precise form and arrangement of the various elements varied from those shown Without departing from the spirit and scope of the4 invention as defined in the appended claims.`

Aprising a two-part connecting rod, a frangi- I ble member operative to normally connect parts of said actuating mechanism to transmit power to the rod, and yielding means so associated with said connecting rod as to normally maintain the parts thereof in one position and operative in case the movement of the ram be arrested at certain points in of said ram is arrested at certain points in.

its path and' said yielding means being operative to yield when the movement of said' ram is arrested at other points in its path.

3.111, an automatic stoker, the combina,-

tion of a ram, a two-part connecting rodv connected therewith the sections of said rod being capable of relative longitudinal movement, a spring adapted to normally force said sections apart, a crank cooperative with said rod, a train of gearing adapted to rotate the crank, and a frangible member interposed in said train and adapted to shear when the motion of the ram is arrested during one portion of its forward stroke, and said yielding means being adapted to yield when the movement of the ram is arrested during another portion of its forward stroke when the parts are of lessangularity and approaching alignment to permit the crank and rod to cross the dead center.

4. In an automatic Stoker, the combination of a ram, means forreciprocating said ram comprising a connecting rod having relatively longitudinally movable sections,

a crank and a train of gearing for rotating the crank, a frangible member interposed in said train and adapted to shear to relieve the tra-in when said ram is incapable of movement in one position, and yielding vmeans interposed between the sections of saidrod adapted to yield to permit relative longitudinal movement of said sections when said ram is incapable of movement -in another position.

'5. In an automatic stoker, the combination of a ram, means for reciprocating said ram comprising a connecting rod having relatively longitudinally movable telescopic sections, means for limiting the movement of said sections with respect to leach other, a crank and a train of gearing for rotating the crank, a frangible member interposed in said train and adapted to normally mainnormally maintain said sections in extended tain the parts thereof in operative assem- -position and to yield to permit relative bled relatlon and to shear when an excessive movement of the sections should the ram 1u strain is brought on said train by the ram become jammed at other points in its path.

5 becoming jammed at certain points in its In witness whereof, I have hereunto Set path and yieldable means interposed bemy hand this 23rd day of February, 1922, tween the sections of said rod adapted to WILLIAM C. STRIPE.

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