US2003385A - Automatic stoker - Google Patents

Description

J. P. NORTON 2,003,385

AUTOMATIC STOKER Filed 061;. 21, 1931 June 4, 1935.

-|NVENTQR JAMES P NOR TON ATTRNEY g Patented June 4, 1935 UNITED STATES PATENT OFFICE AUTOMATIC STOKER Application October 21, 1931, Serial No. 570,164

Claims.

This invention relates to automatic stokers, and more particularly to stokers of the underfeed type in which reciprocable rams mounted in ram casings are utilized to force the fuel into the 5 furnace.

The rams of these underfeed stokers are frequently driven by means of a crank shaft and connecting rods, the connecting rods being pivotally joined to the rams by wrist pins. In some cases the wrist pins extend through slots in the sides of the ram casings, and serve to drive secondary fuel feeding members, such as pusher blocks or reciprocable retort sides. With such a construction, a ram cannot be removed for repair or replacement without first withdrawing the corresponding wrist pin, and this is ordinarily prevented by the proximity of the adjacent ram casing. In order to avoid this difficulty, it has been customary to form each wrist pin of two parts which can be separately inserted or removed. This construction is not only structurally weak, but it provides an insufiicient bearing area for the connecting rod.

It is accordingly the main object of the invention to provide an automatic stoker in which each of the wrist pins which join the connecting rods to the reciprocable rams may be formed in one piece and yet may be readily removed when desired without interference with the adjacent ram casing.

It is a further object of the invention to provide a construction for the wrist pins and their associated parts which will be structurally strong and capable of operating under severe service conditions for a long period without attention, and which will provide ample bearing area and thereby reduce wear to a minimum.

It is a further object of the invention to provide a simple, inexpensive and easily assembled construction including a frangible member which will yield and allow the crank shaft to continue its rotation without damage to any of the parts in case the ram becomes blocked by an obstruction.

With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.

Referring to the drawing illustrating one embodiment of the invention, and in which like reference numerals indicate like parts,

Fig. 1 is a section through a portion of an automatic stoker, the section being taken on the line ll of Fig. 3;

Fig. 2 is a section on the line 2-2 of Fig. 3;

Fig. 3 is a section on the line 3-3 of Fig. 1; and

Fig. 4 is a section on the line 4-4 of Fig. 1.

In the drawing I have shown a portion of a multiple retort underfeed stoker of the general type disclosed in the prior patent to Riley No. 1,090,651. The illustrated embodiment comprises a series of hollow cylindrical ram casings l0 extending forwardly from the front wall II of a furnace, with their axes parallel and in the same horizontal plane. These ram casings are spaced rather closely together, as is necessary in stokers of this type, to match the spacing of the retorts (not shown) within the furnace. An opening 12 is provided through the wall ll at the rear end of each ram casing for the delivery of fuel to the retorts. An opening or throat I4 is formed in the upper wall of each ram casing near the furnace wall H, and a fuel hopper I5 is mounted above each throat. The ram casings ID are held in the desired relative positions by suitable tie members, shown as angle irons I1, l8 and I9 extending horizontally and parallel to the wall I l.

Slidably mounted within each ram casing is a reciprocable fuel feeding ram 21 shaped as a hollow cylinder closed at its rear end and open at its front end. The rams 2i are'arranged to be reciprocated by means of a crank shaft 22 mounted in front of the ram casings and rotatable about a horizontal axis. Each ram is joined to the crank shaft by a connecting rod 23. The crank shaft is arranged to be driven by a speed reducing mechanism 25 to which any suitable source of power may be applied.

On the rear end of each connecting rod 23 I provide a bearing member 2'! shaped as a hollow cylinder. A horizontal cylindrical wrist pin 28 extends through each bearing member and is supported in bosses 29 formed on the inside of the ram. Set screws 30 (Fig. 4) hold the wrist pin in place. It will be noted that this construction forms a strong pivotal connection between each connecting rod and its corresponding ram, and that ample bearing area is provided- The wrist pins 28 are preferably arranged to drive secondary fuel feeding members, such as reciprocable retort side walls as shown in the patent to Riley No. 1,090,651, and for this purpose the ends of the wrist pins are extended through horizontal slots 32 in the sides of the ram casings. These ends are shown somewhat smaller in diameter than the main body of the wrist pin. At each side of each ram casing is a horizontal cylindrical rod 33 (Fig. 2), which is slidable axially through a boss 34 integralwith the ram casing.

It will be understood that each rod 33 may be connected at its rear end to a reciprocable retort side wall (not shown). A bolt 36 forms a forward extension of each rod 33, and these bolts 36 pass through openings or slots 31 in the ends of the wrist pins. A nut 38 (Fig. 2) threaded on each bolt provides an adjustable abutment for the wrist pin to strike on its rearward movement. On the forward stroke the wrist pin contacts with the-heads 39 of the bolts. This construction provides an adjustable lost motion driving connection substantially identical with that disclosed in the above-mentioned patent to Riley.

It will now be seen from Fig. 3 that the wrist pins 28 are too long to be withdrawn in the horizontal axial direction, since they would interfere with other parts and particularly with the adjacent ram casing. The ram casings are carefully aligned and firmly fastened in position, and their removal is a diflicult and laborious task which should not be undertaken unless absolutely necessary. It will also be clear that the rams cannot be removed from the ram casings without first withdrawing the wrist pins.

In order to overcome this difliculty I have provided enlarged openings 4i in the side walls of the ram casings. These openings 4i are preferably located at the front ends of the slots 32, and their dimensions are such that the ram may be turned about its axis and the wrist pin then withdrawn longitudinally without interference with the adjacent ram casing, as indicated by the dot and dash lines in Fig. 3. Ordinarily a section of the crank shaft 22 will need to be removed, to allow complete withdrawal of the ram from the ram casing. It will be sumcient from an operative viewpoint if the openings 4| extend only below the horizontal plane at one side of the ram casing and only above the horizontal plane at the other side. However, I prefer to form both sides of the ram casing in the, same way, to provide a symmetrical construction. The openings 4| in the drawing therefore extend both above and below the horizontal plane.

In the operation of a stoker of this type. one of the rams 2| may become blocked by a foreign body, and it is desirable to provide a frangible member which will yield under these conditions and prevent damage to the driving mechanism. For this purpose I provide a collar 44 which fits loosely upon the outside of the connecting rod and which is normally held in a fixed position thereon by a horizontal shear pin 45 extending through both these parts. The collar 44 normally contacts with the front surface of the bearing member 21 and transmits thereto the force exerted by the connecting rod on the rearward stroke.

1 If this force for any reason'becomes excessive,

the pin 45 will shear and allow the connecting rod to slide through the collar 44 and the member 21.

In order that the connecting rod may slide in this manner, the wrist pin 28 is formed with an opening 41 extending transversely through its center in a horizontal direction, and the bearing member 21 is provided with an opening 48 in direct alignment with the connecting rod. The opening 41 is enlarged at each end in a vertical direction to allow for the angular movement of the connecting rod in a vertical plane, only enough material being removed to avoid interference.

The collar 44 and shear pin 45 are effective during the fuel feeding stroke only, and additional means must be provided to move the ram forwardly. For this purpose I provide a groove 50 extending longitudinally along the outer surface of the connecting rod, and a screw BI is threaded through the front portion of the bearing member 21 with its end located in this groove. In normal operation the screw ii is positioned at the rear end of the groove, which forms an abutment in contact with the screw and thus prevents the connecting rod from sliding forwardly relative to the bearing member. I preferably provide two of these screws SI and two grooves 50, one on the top of the connecting rod and one beneath. It will be clear that the grooves 50, as well as the bolts 36, normally prevent the ram from turning about its axis, and the desired alignment of the wrist pin bearing is therefore maintained.

The operation of the invention will now be clear from the above disclosure. The' crank shaft 22 is rotated by means of a suitable source of power connected to the speed reducing mechanism 25, and the rams 3| reciprocate in the ram casings Ill, delivering fuel from the hoppers ll through the openings i2 into the furnace. The wrist pins 28 reciprocate the rods 33 at a reduced stroke because of the lost motion. If a ram on its rearward stroke encounters an obstruction which produces an abnormal stress on the connecting rod, the pin 45 will shear and allow the connecting rod to slide through the bearing member 21. As the connecting rod moves forwardly, the shoulders at the rear ends of the grooves 53 will contact with the screws ii and thus move the ram to its forward position, where it will remain until the obstruction is removed and a new shear pin inserted. Since each wrist pin is formed of a single piece, an increased bearing area is obtained, as well as a much stronger construction. A connecting rod can be removed at any time by first disconnecting it from the crank shaft and then removing the screws II, which are easily accessible when the ram is in its forward position. A wrist pin can be withdrawn by first removing the set screws 33 and the bolts 36, whereupon the ram may be turned about its axis and the wrist pin slipped out longitudinally through the opening 4|, as indicated by the dot and dash lines in Pig. 3. The entire construction is simple and inexpensive to manufacture and thoroughly dependable in operation, and the various parts may be easily removed for replacement when necessary.

' Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. An automatic stoker comprising a ram casing, a hollow fuel feeding ram reciprocable therein, a cylindrical wrist pin fixed within the ram, a. bearing member pivotally mounted on the wrist pin, a driving connecting rod slidable within the bearing member, the wrist pin having a transverse opening therethrough through which the connecting rod may pass and the opening being enlarged at each end to allow for the angular movement of the connecting rod, and frangible means normally preventing the connecting rod from sliding relative to the bearing member.

2. An automatic stoker comprising a plurality of parallel ram casings, fuel feeding rams reciprocable therein, driving connecting rods, and wrist pins pivotally joining the connecting rods to the rams, the wrist pin for each ram being formed in a single piece and extending through openings in the sides of the ram casings, and these openings being of sufllcient size to allow the ramtobeturnedaboutitsaxisandthewrist pin withdrawn longitudinally without interference with the adjacent ram casing.

3. An automatic stoker comprising a plurality of parallel ram casings mounted side by side and extending forwardly from the wall of a furnace, cylindrical rams reciprocable within the ram casings, driving connecting rods, horizontal wrist pins pivotally joining the connecting rods to the rams, the ram casings having slots in each side and each wrist pin being formed in a single piece with its ends extending through the slots, and mechanism arranged to be driven by the ends of the wrist pins, the slots having enlarged portions of suflicient size to allow the rams to be turned about their axes and the wrist pins to be withdrawn longitudinally without interference with the adjacent ram casings.

4. An automatic stoker comprising a plurality of parallel ram casings mounted side by side and extending forwardly from the wall of a furnace, cylindrical rams reciprocable within the ram casings, a crank shaft mounted in front of the ram casings and rotatable about a horizontal axis, connecting rods actuated by the crank shaft, horizontal wrist pins pivotally joining the connecting rods to the rams, the ram casings having slots in each side and each wrist pin being formed in a single piece with its ends extending through the slots, and mechanism arranged to be driven by the ends of the wrist pins, the slots having enlarged portions at their front ends of sufficient size to allow the rams to be turned about their axes and the wrist pins to be withdrawn longitudinally without interference with the adjacent ram casings.

5. An automatic stoker comprising a ram casing, a hollow fuel feeding ram reciprocable therein, a wrist pin formed in a single piece and fixed within the ram, a bearing member pivotally mounted on the wrist pin, a driving connecting rod slidable within the member, the wrist pin having a transverse opening therethrough through which the connecting rod may pass, frangible means normally preventing the rod from sliding relative to the member, the rod having a longitudinal groove therein which provides a shoulder at the rear endof the groove, and a screw mounted in the bearing member and extending into the groove, the shoulder being arranged to contact with the screw on the forward stroke and thus move the ram to its forward position.

JAMES P. NORTON.

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