US2257488A

US2257488A - Grate actuating mechanism

Info

Publication number: US2257488A
Authority: US
Publication date: 1941-09-30
Anticipated expiration: 1958-09-30

Description

P 30, 1941- G. VON HAASE 2,257,488

GRATE ACTUATING MECHANISM Filed Oct. 20, 1939 5 Sheets-Sheet l 40 2 fl C11 INVENTOR.

6EOBGEVOIY 6410s;

- ATT RNEYfi Sept. 30, 1941. G. VON HAASE GRATE ACTUATING MECHANISM Filed Oct. 20; 1939 3 Sheets-Sheet 2 u M w m 421d f adam a'flzi ATTORNEYS Sept. 30, 1941. G. VON HAASE GRATEV ACTUATING MECHANISM Filed Oct. 20, 1939 3 Sheets-Sheet 3 INVENT OR.

ATTORNEYS Patented Sept. 30, 1941 GRATE ACTUATING MECHANISM George Von Haase, Lakewood, Ohio, assignor to The American Ship. Building Company, Cleveland, Ohio, a corporation of Ohio Application October 20, 1939, Serial No. 300,437

9 Claims.

This invention relates to apparatus for feeding and burning solid fuel, and more particularly to a stoker mechanism having improved grate actuating mechanism.

Mechanical stokers have been provided heretofore of the type having two sets of reciprocable grate bars and a grate actuating mechanism operable to cause a simultaneous forward movement of the two sets of bars and independent retracting movement of such sets. However, in all of the mechanical stokers of this type with which I' am aware, the grate actuating mechanism for obtaining the above-mentioned sequential actuation of the sets of grate bars has been too complex to be practical. Moreover, in the use of stoker mechanisms of this type, the various moving parts are subjected to considerable attrition due to the presence of coal dust or ashes thereon with the result that there is rapid wear and frequent adjustment or replacement of worn parts has been necessary. In view of the complexity of these prior mechanisms, such adjustment or replacement of worn parts could only be done by skilled and specially trained workmen and hence boilers equipped with such mechanisms frequently have had to remain idle until the skilled workmen could be brought to the place where the mechanism was installed.

It is, therefore, an object of the present invention to eliminate these disadvantages and to provide a mechanical stoker having improved grate actuating mechanism of an extremely simple form requiring a relatively small number of moving parts and embodying power means of a form with which power plant operators are generally familiar and on which they are capable of making adjustments and repairs whenever any become necessary.

Another object of my invention is to provide improved mechanism for actuating sets of grate bars in timed sequential relation, in which separate power devices are connected with the respective sets of grate bars and a control means common to such power devices controls the operation thereof to produce said timed sequential actuation of the sets of grate bars.

Still another object of my invention is to provide improved mechanism for actuating sets of reciprocable grate bars in timed sequential rela tion, in which a double-acting reciprocable fluidpressure motor is connected with each set of grate bars so that the power strokes of the motors cause corresponding desired forward or retracting strokes or travel of the respective sets of grate bars.

A further object of my invention is to provide improved grate actuating mechanism, of the type referred to, in which each of the fluid-pressure motors has a valve and a shaft extending adjacent both motors is independently driven for actuating such valves to control the motors and thereby produce the desired timed sequential actuation of the sets of grate bars.

My invention may be further briefly sum marized as consisting in certain novel combinations and arrangements of parts hereinafter described and particularly set out in the appended claims.

In the accompanying sheets of drawings,

Fig. 1 is a side elevation, with portions in. section, showing a mechanical stoker embodying my improved grate actuating mechanism;

Fig. 2 is a partial front elevation showing a furnace front with my improved grate actuating mechanism thereon, this view being taken as indicated by line 22. of Fig. 1;

Fig. 3 is a partial plan View of the grate actuating mechanism, the same being viewed as indicated by line 33 of Fig. 1;

Fig. 4 is a partial side elevation showing, on a larger scale, the cams and linkage for actuating the valves of the fluid pressure motors;

Fig. 5 is a detached view of one of the valve actuating cams;

Fig. 6 is a similar. view showing another valve actuating cam; and

Fig. 7 is a side elevation, partly in section, showing a modified form of my improved grate actuating mechanism.

The embodiments of my invention illustrated in the drawings will now be described more in detail, but before proceeding with the detailed description, it should be understood that my invention is not to be regarded as limited to the particular forms of apparatus and constructions herein disclosed, because it can be embodied in Various other similar mechanisms and devices.

In Figs. 1 and 2 I show a support or mount having my improved grate actuating mechanism thereon and which may be in the form of the furnace front It). The furnace front may be mounted on the outer end of the furnace or firebox of a steam boiler, as indicated in Fig. 1. A plurality of grate bars I2 extend longitudinally of the furnace l I and from the grate upon which the coal or other fuel is to be burned. The bars l2 may consist of two sets arranged with the bars I 2a of one set disposed between the pairs of bars |2b of the other set. These sets of bars are supported for longitudinal reciprocating thereof, interengagement with the bars of the re-' 'spective sets |2a and I221.

The coal or other fuel to be burned may be supplied to the grate bars [2 by any suitable fuel feeding means, for example, I may provide a fuel hopper l4 adapted to contain a supply of coal and a fuel feeding passage I5 with which the bottom of the hopper communicates and in which a reciprocable fuel-feeding plunger I6 operates. The fuel being fed by the plunger l6 advances through the opening I! of the furnace front and then travels down the inclined deflector l8 to the grate bars l2. The furnace front it may also be provided with the usual door controlled opening l9 through which fuel may be supplied to the grate by hand and through which the fire may be worked or tended. The, usual ash pit opening 20 may also be provided in the furnace front for the removal of ashes from the pit beneath the grate bars I2.

For actuating the sets of grate bars I2a and HI), I provide a pair of independent driving motors, in this instance fluid-pressure motors such as the steam engines Zia and 2lb, and also provide a common control means for the engines whereby the operation thereof is controlled so as to obtain the above-mentioned desired simultaneous forward movement and independ-- preferably below the door controlled opening I9.

For this purpose I may provide the furnace front with suitable brackets 22a and 221) on which the motors are mounted. For connecting the engines with their respective sets of grate bars, I may also provide on the furnace front if! a pair of rockshafts 23a and 23b which extend transversely across the face of the furnace front in substantially axially aligned relation with each other. Suitable pairs of bearings 24a and 24b maybe provided on the furnace front for supporting the rock-shafts in this relation. The adjacent or inner ends of the rock-shafts have depending forked arms or levers 25a and 25b mounted thereon. The arm 25a of the rockshaft 23a may be connected with the rocking support l3a as by means of a link 26 which extends through an opening of the furnace front and has its ends pivoted, respectively, to the rocking support and the forked arm. Similarly, the arm 251) may be connected with the rocking support l3b by a link 21 which also extends through an opening of the furnace front and has its inner and outer ends pivoted, respectively, to

identical in construction and, therefore, only one of these engines need be described in detail. As shown in Figs. 1 and 2, the engine may be provided with a double-acting cylinder 30 having a piston 3| reciprocable therein. A piston rod 32 projects from the cylinder and at its upper or outer end is connected with a crosshead or guide 33 which is slidable on a guide rod 34 carried by the cylinder. Ports or passages 35 and 36 (see Fig. 1) connect the upper and lower ends of the cylinder 30 with a valve chest in which the piston valve 3! reciprocably operates. The valve chest may have an intermediate chamber 38 to which steam or other motive fluid under pressure may be supplied through the pipe 39 and may have exhaust chambers 4!] and 4| at the ends thereof which communicate with each other and with an exhaust pipe 42 through the connecting space or passage 43. The valve 31 may have an actuating stem 44 which projects from the upper end of the valve chest.

For connecting the engine with its rock-shaft, I may provide an arm or lever 46 on the outer end of the rock-shaft and connect this arm with the cross-head 33 by means of a pair of spaced links 41. With the arrangement thus far described, it will be seen that when the piston 3| moves upwardly in the cylinder 30, it will oscillate the rock-shaft and the forked arm at the inner end thereof in a clockwise direction and outward or retracting movement will be transmitted to the set of grate bars through the link connecting the rocking support thereof with'the forked arm. Downward movement of the piston in the cylinder of the engine will oscillate the rock-shaft in a counterclockwise direction and this will cause forward movement of the set of grate bars connected with the engine.

As previously stated the engines 2| a and 2lb are controlled so as to produce the desired sequential actuation of the sets of grate bars, and

for this control function I provide valve actuating means which includes linkages 48a and 48b on the respective engines and an independent- 1y driven shaft 49 having cams 5H and 5| thereon which cooperate with the respective linkages. The valve actuating linkage 482) (the linkage 48a of the engine Zia being similar) may comprise a rocking lever 521) having one end thereof pivotally connected with the valve stem 44 and carrying at its other end a roller 53b which engages and follows the contour of the cam 5|. The lever 52b may be a forked lever, or as here shown, may comprise a pair of laterally spaced links having the roller 53b therebetween. This lever is connected at an intermediate point thereof with the rock-shaft 231) by means of a depending link 54. The lower end of the link 54 is connected with the lever 52b by means of the pivot pin 55 and its upper end is eccentrically connected with the rock-shaft 23?) by the eccentrically located pivot pin 56. By using the link 54 for connecting the lever 52b with the eccentric pivot pin 56 of the rock-shaft 231) it will be seen that the ability of this link to swing provides flexibility which permits the end of the lever 52b to have a straightline movement with the valve rod 44 to which it is pivotally connected.

During the operation of the engine the lever 52b is rocked by movement imparted thereto by the cam 5| and by the link 54 and such rocking causes reciprocation of the valve 31 which controls the supply of motive fluid to the ends of the cylinder 39 and the discharge of exhaust fluid therefrom. The linkage 48b functions in a manner generally similar to the reversing gear of a reciprocating engine and at times the rocking ofthe lev'er 52b is caused by the cam 5| and at other times by the eccentrically arranged link 54 and at still other times the movement of the lever 52b or the positioning thereof is the resultant effect of the movements of the cam 5| and the link 54.

I As shown in the drawings the shaft 49 of the control means may be mounted for rotation on the furnace front l and extends transverse- 1y of the same adjacent the two engines 2 la and 2|b. 'This shaft is driven continuously during the operation of the stoker by an independent powermeans which, as shown in Fig. 3, may comprise a small electric motor 58 which is connected with the shaft 49 through a reduction gear 59 and a belt 60.

In the sequence of operation above indicated for the sets of grate bars, the set |2a is retracted first and may, therefore, be referred to as the leading set and the set 2b which is later retracted, may be referred to as the following set. By providing the cams and 5| with the proper contour and arranging them on the shaft 49 in appropriate angular relation the engines 2|a and 2|b can be controlled so that the engine Zia-will move first in the cycle of operation to retract the set of grate bars |2a,' after which the engine 2lb will move to retract the set of grate bars I21) and following this both engines will move simultaneously to advance both sets of grate bars together. By referring to Figs. 4, 5 and 6, it will be seen that the leader cam 50 has a rising section 62, adwell section 63 and a falling section 65a.. Similarly, the cam 5| has a rising section 66, a falling section 6511 of identical contour with the falling section 65a of the cam. 50, and a dwell section 61. With the cams mounted on the shaft 49 in the relative angular position shown in Fig. 4, it will be seen that clockwise rotation will cause a sequential operation of the valves of the two engines 2| (1 and Zlb during which the rising section 62 of the cam 50 will pass under the roller 53a of the rocking lever 52a and will lift the same to thereby cause downward movement of the valve of the engine 2| :1. This will permit pressure fluid to enter the lower end of the cylinder 30 and the resulting upward movement of the piston 3| will cause the set of grate bars Ila to be retracted.

The roller of the lever 52a next traverses the dwell section 63 of the cam 59 during which time the valve of the engine 2| a remains in its lower position and the grate bars |2a are held in their retracted position by the pressure fluid in the lower end of the cylinder of the engine. During the time that the dwell section 63 of the cam 50 is being traversed by the roller of the lever 52a and the grate bars IZa' are thus being held in their retracted position, the rising section 66 of the cam 5| passes under the roller 53?) of the lever 52b causing downward movement of the valve 31 of the engine 2| b. Thereupon pressure fluid is admitted to the lower end of the cylinder 30 of this engine resulting in retracting movement of the set of grate bars I'Zb.

Further clockwise movement of the cams 59 and 5| causes their falling sections 65a and 65b, which are of identical contour on both cams, to passunder the rollers of the levers 52a and 52b whereupon both levers will be rocked. at the same time in a direction to move the valves 31 of both engines upward to admit pressure fluid to the upper ends of the cylinders.

The resulting si- F multaneous downward movement of the pistons of both engines will cause the sets of grate bars |2a and |2b to be moved forward at the same time. By the time that the shaft 49 has rotated through an angular distance to bring the radial line 68 under the rollers of the levers 52a and 52b, the forward movement of the sets of grate bars will have been completed. As the camscontinue to rotate the risingsection 62 of the cam 50 again passes under the roller of the lever 52a to lift this lever and again cause retracting movement of the set of grate bars IZa. During this interval, the dwell section 61 of the cam 5| passes under the roller 53b of the lever 52b and during this travel the valve of the en-- gine 2|b remains in its upper position so that pressure fluid will be maintained in the cylinder 3| above the piston resulting in the set of grate bars |2b being positively held in their forward position while the set |2a is being retracted. As the shaft 49 continues to rotate thereafter, the engines will be operated through recurring cycles similar to that above explained and the sets of grate bars will be repeatedly reciprocated in their timed sequence. The rapidity at which these cycles of operation are carried through will depend upon the speed at which the shaft 49 is rotated and by appropriately controlling the speed of the motor 58 this can be established or varied as desired.

In further explanation of the operation of the valve linkage above described I might point out that the connection of an intermediate part of the lever 52b with the eccentric pin 56 of the rock-shaft 231) (as obtained in this instance by the'link 54) provides a follow up movement or effect in the actuation of the valve 3'! by which operation of. the piston 3| is obtained at a desired slow rate and in accordance with the load or resistance imposed thereon by the set of grate bars |2b. Thus when the apparatus is started up the rock-shaft 23b is at first stationary and the clockwise rotation of the shaft 49 causes the cam section 69 to lift the lever 52b and this lever, rocking on the link 54, shifts the valve 31' downwardly to admit steam to the lower end of the cylinder. The resulting upward piston movement causes actuation of the rockshaft which lifts the link 54 to thereby counteract more or less the movement imparted to lever 521) by the cam and cause a partial reclosing of the valve. This follow up action of the link 54 thus prevents the piston from being actuated with a sudden or slamming action.

If the set of grate bars |2b should become jammed or stuck the rock-shaft 23b! will be stopped or slowed down and hence the link 54 will be less effective in following up or counteracting the movement of the lever 52!) by the cam 5| and this cam will cause the valve 31 to be opened wider and wider until a suflicient steam. pressure acts on the piston to overcome the stuck or jammed condition. The resulting movement of the rock-shaft and the link 54 then partially recloses the valve to prevent a subsequent too rapid action of the piston. In explaining the action of the link 54 I have referred particularly to the rock-shaft 23 and the lever 52%) but it will be understood that the link 54 cooperating with the rock-shaft 29a and the lever 52a functions in a similar manner. It will be notedpalso that the valve 31 controls the supply of steam to one end of the cylinder and simultaneously controls the exhaust from the opposite end. Thus when the piston movement is slowed or stopped by the above-mentioned reclosing movement resulting from the action of the link 54, the valve recloses the exhaust passage from the opposite end of the cylinder atthe same time.

The rollers of the levers 52a and 52b of the valve linkages may be maintained in engagement with the cams 5i] and 5| by appropriate spring pressure, or as shown in this'instance, by providing the engine valves 31 with a balancing piston 69 against which steam or other pressure fluid supplied by the pipes exertsa force normally tending to lift the valves. 7

' The reciprocable fuel feeding plunger I6 above referred to, may be driven in any appropriate manner, but is preferably actuated by motion transmitted from the rock shaft 23a so that the operation of the plunger will bein timed relation to the actuation of the sets of grate bars. For thi purpose I may provide an arm H on the rock-shaft 23 which is connected with the arm 12 of the shaft 13 by a link 74. Another arm 15 of the shaft 73 has operative connection with the reciprocable plunger I6. A lost motion connection 76 may be provided between the link 14 and the arm 12 and can be adjusted by the hand wheel I! to thereby adjustably vary the length of stroke through which the fuel-feeding plunger i6 is actuated.

In '7 I have shown grate actuating mechanism similar to that above described, but in which a different form of connection or linkage is employed between the driving motors or engines and the'rock-shafts actuated thereby. In this modified arrangement I show an engine 80 which is one of a pair of similar double-acting reciprocable fluid-pressure motors or steam engines. These engines or motors, as here shown, have'a cylinder 8| in which a piston 82 is reciprocable and a piston rod 83 projecting from the cylinder carries a rack 84. A gib 85 connected with the rack 84 has slidable bearing engagement with the guide plate 86 of the guide bracket 81 for taking lateral thrust to which the rack; may be subjected. A gear sector 88 carried by an arm 89, which is mounted on the rock-shaft 90, meshes with the rack 84 so that reciprocation of the piston will cause oscillation of the rock-shaft. The engine 8'0 embodies a valve for controlling the flow of fluid to and from the ends of the cylinder BI and is provided with the valve linkage 9| and an actuating cam 92 similar to the linkages and earns above described for the engines 2 la and Eli).

From the foregoing description and the accompanying drawings, it will now be readily seen that I have provided a mechanical stoker having improved grate actuating mechanism of simplifled form and embodying a minimum number of moving parts. It will be seen furthermore that in my improved grate actuating mechanism I employ a separate engine or power device for each set of grate bars and provide an independently driven common control means for the engines whereby they operate in a cycle to produce a desired simultaneous forward movement and independent retracting movement of the sets of grate bars. It will also be seen that by providing a double-acting reciprocable engine for each set of grate bars, a direct actuation of the sets of bars can be obtained in accordance with the power strokes of the engines. It will mechanism will be of a type with which power plant operators are generally familiar and on which repairs and adjustments can be made by them thus avoiding the delay and expense which would otherwise be encountered in calling upon skilled technicians or engineers for the making of such repairs or adjustments.

While I have illustrated and described my stoker and improved grate actuating mechanism in a more or less detailed manner, it should be understood that I do not wish to be limited to the precise construction and arrangements herein disclosed but regard my invention as including such changes and modifications as do not constitute a departure from the spirit of the invention and the scope of the appended claims.

Having thus described my invention I claim:

1. In apparatus of the character described, a support, a plurality of sets of movable grate elements, rock-shafts journaled on said support and connected with the respective sets of grate elements, fluid-pressure motors mounted on said support and connected with the respective rockshafts, a valve for each motor, and means for timing the actuation of said valves including a separate power device and a shaft driven thereby and having a cam thereon adjacent each motor.

2. In apparatus of the character described, a support, a pair of sets of movable grate elements, a pair of rock-shafts journaled on said support in substantially aligned relation, means connecting the adjacent ends of said shafts with the respective sets of grate elements, a pair ofdouble-acting reciprocating fluid-pressure motors mounted on said support and connected with the respective rock-shafts adjacenttheir outer ends,

each of said motors including a valve, a shaft" mounted on said support to extend adjacent both of said motors, independent power means for driving the last-mentioned shaft, and cams on said last-mentioned shaft for causing timed actuation of the valves of said motors.

3. In apparatus of the character described, a pair of sets of reciprocable grate elements arranged for simultaneous movement through a forward stroke and independent movement through their retracting stroke, a pair of doubleacting fluid-pressure cylinders having reciprocating pistons connected with the respective sets of grate elements so that a power stroke of each piston causes the corresponding set of grate elements to be moved through its stroke, a valve for each cylinder, a shaft extending adjacent both cylinders, means for continuously and independently driving said shaft during the operation of the apparatus, and cams on said shaft for actuating said valves in timed sequence to cause said simultaneous forward movement and independ ent retracting movement of said sets of elements.

4. In apparatus of the character described, a'

cylinders, independent power means for driving said shaft, cams on'said shaft adjacent the respective cylinders, and means actuated in part by said cams and partially by the movement of said pistons for shifting said valves to control the operation of said cylinder-s.

5. In apparatus of the character described, a support, a pair of sets of movable grate elements, a pair of rock-shafts journaled on said support in substantially aligned relation, means connecting the adjacent ends of said shafts with the respective sets of grate elements, a pair of double-acting reciprocating fluid-pressure motors mounted on said support and connected with the respective rock-shafts adjacent their outer ends, each of said motors including a valve, a shaft mounted on said support to extend adjacent both of said motors, independent power means for driving the last-mentioned shaft, cams on said last-mentioned shaft adjacent the respective motors, valve operating levers arranged to receive movement from said cams, and means whereby said rock-shafts impart movement to said valve operating levers so as to at least partially counteract the movement received from said cams.

6. In apparatus of the character described, a support, a pair of sets of movable grate elements, a pair of rock-shafts journaled on said support in substantially aligned relation, means connecting the adjacent ends of said shafts with the respective sets of grate elements, a pair of double-acting reciprocating fluid-pressure motors mounted on said support and connected with the respective rock-shafts adjacent their outer ends, each of said motors including a valve, a shaft mounted on said support to extend adjacent both of said motors, independent power means for driving the last-mentioned shaft, cams on said last-mentioned shaft adjacent the respective motors, valve operating levers having one end thereof connected with said valves and the other end in engagement with said cams, and means pivotally connecting an intermediate point of said levers with said rockshafts at an eccentric point of the latter whereby actuation of said levers by said cams is at least partially counteracted by movement imparted thereto by the rock-shafts.

7. In apparatus of the character described, a supporting structure having an upright front wall, a grate extending forwardly away from said front wall and comprising a pair of sets of movable grate bars adapted to support a fuel bed, said sets being arranged for substantially simultaneous forward movement for advancing the fuel bed and an independent retracting movement, a pair of rock-shafts journaled on said front wall and extending in a direction transversely thereof, means connecting the shafts with the respective sets of grate bars for transmitting motion thereto, a pair of doubleacting fluid-pressure cylinders mounted on said upright wall and having reciprocating pistons connected with the respective rock-shafts so that a power stroke of each piston causes the corresponding set of grate bars to be moved through its travel, control valves adjacent the cylinders and adapted to be actuated in timed relation such that said pistons produce said simultaneous forward and said independent retracting movement of said sets of grate bars, and means for causing such timed actuation of the valves including a common valve-actuating shaft extending transversely of said upright wall and a continuously operating power device connected With said valve-actuating shaft.

8. In apparatus of the character described, a supporting structure having an upright front wall provided with a fire-tending opening, a grate extending forwardly away from said front wall and comprising a pair of sets of movable grate bars adapted to support a fuel bed, said sets being arranged for substantially simultaneous forward movement for advancing the fuel bed and an independent retracting movement, a pair of rock-shafts journaled on said front wall and extending transversely thereof in substantially axially aligned relation, means connecting the adjacent inner ends of the shafts with the respective sets of grate bars for transmitting motion thereto, a pair of double-acting fluidpressure cylinders mounted on said upright wall on opposite sides of said fire-tending opening and having reciprocating pistons connected with the outer ends of the respective rock-shafts so that a power stroke of each piston causes the corresponding set of grate bars to be moved through its travel, control valves adjacent the cylinders and adapted to be actuated in timed relation such that said pistons produce said simultaneous forward and said independent retracting movement of said sets of grate bars, and means for causing such timed actuation of the valves including a common valve-actuating shaft extending transversely of said upright wall and a continuously operating power device connected with said valve-actuating shaft.

9. In apparatus of the character described, a supporting structure having an upright front wall, a grate extending forwardly away from said front wall and comprising a pair of sets of movable grate bars adapted to support a fuel bed, said sets being arranged for substantially simultaneous forward movement for advancing the ifuel bed and an independent retracting movement, a pair of rock-shafts journaled on said front wall and extending in a direction transversely thereof, means connecting the shafts with the respective sets of grate bars for transmitting motion thereto, a pair of doubleacting fluid-pressure cylinders mounted on said upright wall and having reciprocating pistons connected with the respective rock-shafts so that a power stroke of each piston causes the corresponding set of grate bars to be moved through its travel, control valves adjacent the cylinders and adapted to be actuated in timed relation such that said pistons produce said si multaneous forward and said independent retracting movement of said sets of grate bars, a Valve shaft extending transversely of said upright wall and carrying valve-actuating cams, and a continuously operating power device connected with said valve shaft, the contour of said cams being such that the valve for one cylinder will be actuated to maintain fluidpressure in such cylinder for holding the corresponding set of grate bars stationary while the other set is being retracted by its cylinder.

GEORGE VON HAASE,