US2080838A - Stoker drive - Google Patents

Description

May 18, 1937. E. R. STONE 2,080,838

, VSTOKER DRIVE Filed July 50, 1956 3 Sheets-Sheet l H/A-T Pics 2 x k NI 2 9 .11., m u 0 5 M m ET 5 H EA m Tm. 5 H 5 w W Ta L. .H ,mm v. 7 S a .F 4 N 5 w 5 2 E. W 5s 2 2 Patented May 18, 1937 STOKER DRIVE Earll It. Stone, Lansdowne, Pa., assignor to Westinghouse Electric & East Pittsburgh, Pa., sylvania Manufacturing Company,

a corporation of Penn- Application July 30, 1936, Serial No. 93,488

3 Claims.

My invention relates to motor devices of the steam type for operating underfeed stokers and for other apparatus requiring a'reciprocating drive; and it has for an object to provide apparatus of this character constructed and arranged to be economical in the use of steam.

It is commonpractice to reciprocate rams of single retort underfeed stokers and the like by means of steam operating cylinders, the cylinder having an operating piston therein connected to the ram. Steam is frequently supplied to and exhausted from the ends of the operating cylinder'by means of a valve arrangement including a main valve anda pilot valve, the main valve serving to supply vsteam to or to exhaust steam from the operating cylinder and the pilot valve constituting a part of the means for securing operation of the main valve. In this arrangement, the main valve is usually provided with. motive means consisting of opposed piston faces, the larger piston face forming a part of an expansible and contractible steam chamber and the smaller piston face forming a part of a liquid chamber of the same character. The pilot valve serves to control the admission of steam to or the I exhaust of steam from the steam chamber. With liquid under pressure supplied to the liquid cham-,

ber, if steam under pressure is ssupplied'to the steam chamber, the differential force thereof secures movement of the main valve against the liquid pressure; and, if the steam chamber is connected to exhaust, the liquid supplied to the liquid chamber is effective to secure movement of the main valve in the opposite direction. It is common practice to restrict the flow to and from the liquid chamber, with the result that movement of the valve may be timed to secure the desired speed of operation, such timing involving variation in the interval operating piston. Heretofore, steam has been supplied to the operating piston for longer intervals than are actually required with the consequent increased opportunity for wastage of steam due to leakage. With completion of a stroke a of the operating piston, there is no necessity for -the continued application of steam under pressure to the same face of the piston. Accordingly, a further object of my present invention is to provide a controlling main valve for an operating cylinder of this character which is constructed and arranged to interrupt the supply of steam to the operating cylinder immediately upon completion of a working stroke.

A further object of my invention is to provide a double-acting operating cylinder of the steam between strokes of the type provided with admission and exhaust ports for each end of the cylindercontrolled by a main valve having operating means includingopposed piston areas, one piston area being arranged to have steam under pressure applied thereto and the other piston area having liquid under pressure continuously applied} thereto, the piston areas and the pressures being so related that, with steam admitted by the pilot valve to one of the piston areas, when the pilot valve is moved to one position by the operating piston, the main valve operating means moves against theliquid 1 pressure to effect openingand closing of said ports incident to effecting a stroke of't he operating piston in one direction, and, with steam exhausted from the first piston area by the pilot valve when I the latter is moved to its other position by the operating piston, the valve operating means moves inthe other direction due to the pressure of medium applied to the second piston area to open and close said ports incident to effecting a working stroke of the operating piston in the other direction, together with means for controlling the flow of liquid to and from said other piston area, the latter means including anaccumulator iunctioning to permit rapid movement during the initial portion of each stroke of the main valve so that the latter may be brought rapidly to cut-oiI position and the remainder of 'the stroke of the main valve occurring at a rate dependent upon the rest riction, this operation resulting in rapid closure of a steam port by the main valve just as soon as the operating piston reaches the end of each stroke.

These and other objects are effected by my invention, as will be apparent from the following description and claims, taken in connection with the accompanying drawings, forming a part of thisapplication, in which:

Fig. l is a side elevational invention applied to an underfeed stoker and showing portions of the apparatus in section;

Fig. 2 is a section taken longitudinally of the operating cylinder and the pilot valve chamber and transversely of the main valve and main valve operating means;-

Fig. 3 is a diagrammatic view showing the relation of the water supply means to the main valve operating means, the principal parts being shown in section;

Fig. 4 is a diagrammatic tion of the pilot and main valves;

trative of the operation of the device; and,

view showing my view showing the rela underfeed stoker, at

nism in the usual way. As shown in Fig. 2, the

communication with 2| and 20. t

The piston valve 30 is made hollow, as shown at 34, so as to provide for exhaustfrom the supply either of the supply ports the supply ports 2| and 20 and to place the latter ports alternately in communication with the exhaust, the arrangement being such that the pressure port iscut off from both or the supply ports 2,oso,eaa

slide type, and it is actuated by means of a rod 46 having spaced abutments 4'! to be contacted by the piston abutment member 46. The valve 45 is shown by way of example, as being of the D-slide type having a recess 50 adapted to place the port 5| either in communication with the port 52 or with the port 53', the port 52 communicating with the arcuate recess 54 terminating in a port 55 formed in the cylinder 22 and in direct communication with steam supply chamber 25. Steam whereby the steam space 46 is placed in communication with the maintained on the piston face 43 then causes the piston valve to move toward the left.-

piston after a working stroke'oi' the latter is completed. As already pointed out, it is not only useless to maintain steam pressure on the operating piston afterthe latter has completed a workexhaust, and the liquid pressure cylinder 4 has admission and exhaust ports I 6 under pressure is supplied from the line 26 10 and I1 adjacent the ends thereof, such ports being through the ports 24 and 25 into the space beconnected, by means of the passages l8 and I9 to a tween the piston portions 32 and 33, through the valve, for example, a piston valve having ports 20 arcuate channel 54 and the port 52. The port and 2| communicating with the passages l8 and 5| is placed in communication with the channel 15 I3 and formed in the bushing 22, the latter being 5'! formed in the periphery of thebushing 22 and carried, for example, by the cylinder head 23. communicating with the steam chamber 40. The The main valve cylinder or bushing has steam port 53 communicates with a channel 58 formed pressure ports 24 and 55 connected with the steam in the bushing and is connected to the exhaust supply chamber 25 formed in the head 23. The space 36. 20 chamber 25 is preferably connected by a steam As the operating piston l5 reaches the end of a pipe 26 (Fig. 1) with the steam supply line H. working stroke in one direction, the pilot valve 45 The head 22 also has an exhaust chamber 21 places the pressure supply port 52 in communiprovided with an exhaust connection 28. cation with the port 5| to supply steam to the A piston valve 36 is arranged in the cylinder or chamber 40, whereupon steam pressure applied 25 bushing 22 and it has piston portions 3|, 32, and to the pistonface 39 of the piston valve causes the 33, the piston portions 32 and 33 being so spaced latter to move toward the right in Fig. 3. On the and arranged that the space therebetween is in other hand, with completion of the stroke of the constant communication with the pressure port operating piston in theother direction, the pilot 24 and is adequate to place the pressure port in valve places the ports 5| and 53 in communication,

ports 2|. When the latter are in communication ,AS shown in Figs. 1, 3, and.5, the plunger cyl- 35 with the space between the piston portions 3| and inder or chamber 42 is connected, by means of 32, the bore 34 communicating, by means of ports a conduit 60, to a condensate standpipe 6| in 35, with such space, and also communicating, by communication with the steam supply pipe means ot'the ports 36, with the space to the right the conduit 63 including a suitable restriction,

40 of the piston'portion 33, as shown in Fig. 3, such such as the needle valve 62, so that the rate of 40 space being in free communication with the pas flow through the conduit may be suitably varied. sage 33 leading to the exhaust space 21. Heretofore, upon movement of the operating If the piston valve occupies: the position shown piston to one end of a working stroke, application in Fig. 3; it will be apparent that the steam supply of steam under pressure to the piston is continued port 24 communicates with the pressure supply until such time as the main valve, after reversal 45 ports 2| to supply steam to one end of the operof its direction, is moved sufflciently to cover the ating cylinder At the same time, theother supply valve port. Hence, due to the slow movement of ports 20 are in communication-with the exhaust. the main valve after reversal and until the port The piston valve is operated to place the presis covered, full steam pressure is maintained for sure port 24 alternately in communication with an appreciable interval oftime on the operating 50 for a substantial portion of the stroke of the piston valve.

The piston valve 30 has a piston face 39 forming a closure for the steam chamber 40. Also, the

piston valve has, at its opposed end, a plunger 4| of smaller. diameter than the piston face 39 and arranged in the plunger cylinder or chamber 42. As will be pointed out, the plunger piston face 43 is subjected continuously to liquid under pressure and steam under suitable pressure is intermittently admitted to the chamber 40 to move the valve in one direction. If the steam chamber 40 s connected to the exhaust, :then pressure of liquid supplied to the chamber 42 causes the movement or the valve in the other direction.

Steam is admitted to and exhausted from the steam chamber 40 by means of a pilot valve 45 operatively connected to the operating piston l5, the arrangement being such that the valve 45 is actuated at the end of each stroke of the oper- 7s sting Piston. As shown, the valve 45 is 01 the ing stroke, but maintenance of such pressure dur- 55 ing such interval causes excessive leakage.

Accordingly, I provide apparatus arranged. in conjunction with the restriction 62 and which serves to secure rapid movement of the. main valve 30 at the end of each working stroke of the 60 operating piston to cause the main valve to reach a cut-ofi position rapidly. To thisend, an ac-, cumulator 63 is connected to the conduit 60 between the chamber 42 and the restriction 62 and for a rapid surge of liquid,

valve 30 in both directions. I

Any suitable type of accumulator maybe used. In Figs. 1, 3, and 5, the accumulator is shown as being comprised by a body 64 having a liquid.- 70 tight displacement member 65 therein and separating the chambers 65aand 652), the chamber 65a communicating, through the passage 61 with the passage 60 between the chamber 42 and the restriction 62 and the chamber 65b communicat- 7 ing, by a passage 86, with the portion of the passage 60 between the restriction 62 and the standpipe 6|. In operation, it will be apparent that, with the valve 30 in the position shown in Fig. 3, such valve may move rapidly to the extent permitted by the volume of liquid expelled from the chamber 42 and sufficient to satisfy the accumulator in moving the displacement member thereof from the position shown to its extreme right-hand position, further liquid expelled from the chamber 42 being forced to pass through the restriction 62 before going to the standpipe 6|. On the other'hand, assuming that the valve 30 is in its extreme right-hand position in Fig. 3 and the chamber 40 is connected to the exhaust, then the valve 30 moves rapidly toward the left to the extent of the volume of liquid discharged from the accumulator incident to movement of its displacement member 65 from its extreme right-hand to its extreme left-hand position.

While I prefer to use the form of accumulator illustrated in Figs. 1, 3 and 5, the form shown in Fig. 6 may be used, if desired. In this view, the accumulator 63' is connected to the passage 60 between the chamber 42 and the restriction 62, the accumulator including a body 64' and a displacement member 65, the latter being in the form of a weighted plunger fitting the bore 64 to provide an expansible and contractible chamber 65 communicating with the passage 60 between the chamber 42 and the restriction 62. As before, this arrangement provides for a limited rapid surge of flow of liquid during'initial portions of travel of thevalve 30 in each direction, whereby such initial portions of valve travel may occur rapidly so as to bring about quick coverage of a port after completion of the working stroke by the operating piston. I

Referring again to Fig. 3, assuming completion of a stroke of the operating piston 15 in one di: rection, then, as such stroke is completed, the pilot valve 45 is shifted to supplylsteam to the chamber 40, whereupon the valve 30 moves rapidly, because of the rapid discharge of liquid from the chamber 42, permitted by displacement of the accumulator 63, to cut-off communication between the ports 2| and 24, communication of such ports having been responsible for the admission of steam to the operating cylinder to effect said stroke of the operating piston, and, thereafter, the accumulator having reached the limit of its displacement in one direction, further discharge of liquid from the chamber 42 must occur through the restriction or metering device 62, the latter being adjusted so as to secure any desired time of travel for the remainder of the stroke of the piston valve so as to vary the average movement rate of the motor device. On the other hand, assuming the completion of a stroke of the operating piston IS in theother direction, the pilot valve45 is shifted at the end of such stroke to connect the steam chamber 40,

with the exhaust, and then liquid supplied to the chamber 42 is immediately effective to move the piston valve 30 from its extreme right-hand position toward the left, liquid being rapidly supplied to the chamber 42 from the accumulator to effect rapid interruption of communication between the ports 20 and 24, which communication was responsible for the stroke last mentioned, and, the

displacement of the accumulator having been completed, the piston valve continues to move toward the left at a rate dependent upon adjustment of the restriction or metering device.

Aside from the arrangement of the accumulator 63 servingthe purpose just indicated, it is necessary that the admission ports 20 and 2| shall be so spaced and be so related to the piston, valve portions 32' and 33 thata desired lapped condition may occur through a substantial portion of the stroke of the piston valve. Referring to Fig, 3, with the piston valve'l'30 in the position shownfljustfasisoon as steam is admitted to the chamber 40, incident to shifting of the pilot valve 45 by the operating piston,

the piston valve moves quickly toward the right to an extent sufficient to cover the port 2|, displacement permitting of this quick movement being provided by the accumulator. 'I'herefore,

as will be seen from Fig. 3, the piston valve has considerable'travel before communication of the pressure port 24 with the admissionpo'rt2fl is established to one end of the operatingcylinder to secure the next workingjstroke of the operating piston and this idle orfcut-oif travel of the piston valve takes place at a desiredslow rate depending upon the setting of the needle valve or'restriction 62.- Just assoon as com munication of the supply port 24' wi'ththe adfmission port'20 is established,fthe next working stroke of the operating piston occurs; and, at the end of the latter, the pilot valve is shifted to place the steam space 4.0 in. communication with the exhaust, .whereupon the liquid underpressure supplied to the piston face 43 ;is'effective to move the piston valve to the left, the initial portion of this movement taking place rapidly to the extent of the displacement of the accumulat'or' 62 followed by slow. movement of the piston valve, a substantial portion 6f v its travel occurring, due to the lapped arrangement, before re-establishment of communication between the ports2land 24.

Referring more particularly to the restriction or orifice, at 62, this preferably takes the form of a plunger or 'needle valve 68 arranged in' a guide bushing 69 and having valve portions ID and H, the respective valve portions cooperating with the upper seating" edge 12 and with the downwardly-tapered boref'l3 of the valve bushing", the elongated valve element 1| being preferablyflattened or grooved longitudinally to. provide a minimumflow area or "orifice. Longitudinal l movement of the plunger obvi ously provides for a very gradual change in v area of the orifice. As the minimum area or orifice or/restriction is reached, the'valve portion 10 engages the seat," to interrupt flow.

As shown, one adjacent end of the conduit 60 is connected so as to be in communicationwith the lower end of the valve element 14 and the other adjacent end is connected so as to com I municate with passages and ports 15 arranged 'in the lower end ofthebushing 69.

As diagrammatically indicated in Fig.' 1,"the valve plunger 68 is moved longitudinally: j by means of a lever 16 having one end fulcrumed at 11 and having a weight, orequivalent means, 18 for biasing the other end of the lever downwardly, any 3 suitable means being used to operate against the force of the weight toefiect upward movement of the plunger 68. As indicated-in Fig. 1, a master regulator may be connected to the lever I6 so as to operate against the weight, whereby, in response to load conditions imposed on the boiler, the stoker speed may be regulated to suit such load conditions.

The lever 16 may also be manually operated merely by having the stop 80 carried by the cordance With 'completion,, of-a working stroke by the operating piston, the pilot valve is shifted to either of its two positions to bring about movement of the main valve, the latter having a rapid initial portion of travel, sumcient'to cover the steam port for the operating cylinder, due to the by-pass eflfect provided by the accumulator. The aggregate speed of the motor device, or the number of strokes per unit of time, may be varied as heretofore by adjustment of the restriction; however, because of the by-pass effect of the accumulator, the restriction is in-- effective to cause motion of the main valve at a slow rate during the interval between the end of a working stroke and covering of the steam port responsible for such working stroke, with the result that, during said interval, the main valve moves rapidly to cover the port, thereby reducing the interval and minimizing the loss of steam due to leakage by the piston during the interval.

While I have shown my-invention in two forms, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon asare imposed by the prior art ,or as are specifically set forth in the appended claims.

What I claim is: a

1. In a reciprocatory double-acting motor device, sources of steam and'liquid under pressure, an operating cylinder having ports communicating with the ends thereof, an operating piston in the cylinder, a valve for controlling said ports, said valve having operating means including'opposed piston faces, means cooperating with the one piston face to provide a steam chamber, means cooperating with the other piston face to provide a liquidchamber, a connection including a restriction between said liquid source and said liquid chamber, a pilot valve moved atstroke ends of the operating piston for connecting said steam chamber either with said source of steam under pressure or with exhaust, said steam and liquid pressures and said steam and liquid pisrelation that the steam ton faces having such pressure is capable of moving the valve against the liquid pressure, and a liquid accumulator arranged in relation with said restriction to pro-' videfor rapid displacementof an initial quantity of liquid leaving or entering said liquid chamber incident to movement of the valve.

2. A reciprocatory, double-acting motor device comprising sources of steam: and liquid under with my invention will be apparent. Y

substantially the same pressure;

cylinder having ports communicating with the ends thereof; an operating piston in the cylinan operating der; a valve chamber having admission and ex-,

haust ports connected to said cylinder ports, a pressure port, and an exhaust connection; a valve arranged in said valve chamber and having portions for covering and uncovering the admission and exhaust ports and arranged to place the latter alternately in communication with the .pressure port and with the exhaust connection;

and exhaust port the posed piston faces; means cooperating with the a larger piston face to provide a steam chamber; means cooperating with the smaller piston face to provide a liquid chamber; a connection including a restriction between the liquid source and the liquid chamber; a pilot valve moved at stroke ends of the operating piston for connecting the steam chamber with the source of steam under pressure or with the exhaust; and an accumulator connected in relation to the restriction to provide for rapid movement of the initial fraction of liquid leaving or entering the liquid chamber-to provide, with completion of a working stroke of the operating piston, for rapid travel of the valve to interrupt the supply of steam to the operating cylinder and responsible for the working stroke just completed.

3. A reciprocatory, double-acting motor device comprising sources of steam and liquid under substantially the same pressure, an operating cylinder, an operating piston'in the cylinder, a valve for controlling the admission and exhaust of steam to each end of the cylinder, said valve having larger and smaller opposed piston faces, means cooperating with the larger piston face to provide a steam chamber, means cooperating with the smaller piston faces to provide a liquid chamber, a connection including a restriction between the liquid source and the liquid chamber v a pilot valve moved at stroke ends of the operating piston for connecting the steam chamber to the source of steam pressure or to the exhaust,

and an accumulator arranged with respectto the restriction to provide for rapid movement of the initial fraction of liquid leaving or entering the liquid chamber to secure, as each working stroke of the operating piston is completed, a rapid initial portion of the valve stroke to quickly interrupt the supply of steam to the operating cylinder and responsible for the working stroke just completed, saidaccumulator including a pair of chambers communicating, respectively, with said connection at opposite sides of the restriction and a movable water-tight element separating the chambers.

M EARLL R. STONE.

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