US2236665A - Hydraulic actuating mechanism for stokers - Google Patents

Description

April l, 1941. R 1 BEERS 2,236,665

HYDRAULIC ACTUATING MECHANISM FOR STOKERS Filed June 26, 1939 2 Sheets-Sheet l FIGJ.

l INVENTOR.

ROYCE LBEERS ATTORNEYS April 1, 1941.

I R. lA.. BEERs f HYDRAULIC ACTUATING MECHANI S M FOR STOKERS Fiied June 26, z'sheets-shet 2 FIG. 2

INVENTOR.

ATTORNEYS Patented Apr. l, 1941 UNITED STATES PATENT* OFFICE- nvnnavucsoroama Mscnmsm Fo sroxnas Boyce L. Beers, Birmingham,

Detroit Stoker Company, poration of Michigan Mich., assignor to Monroe, Mich., a cor- ,Atpscsacn June za, 193s, sensi No. 281,302

4 chime (ci 1er- 157) The invention relates to stokers of that type in which the fuel is periodically fed into the furnace by the operation of a fuel pusher or ram. More particularly. the invention relates to the means for operating the ramand has for its object the obtaining of a simple construction having certain advantages over and avoiding certain defects 4Vof constructions heretofore used for this purpose. To this end the invention consists:Y rst, in the peculiar construction of the hydraulic actuating mechanism; second, in

cycles independently of the speed of movement of the ram; third,V in the means for guarding against danger of breakage of the parts in case of obstruction to the feed; fourth, in the means forI maintaining the device operative, at least to some extent, even where there is partial obstruction to the feeding; fifth, in' various other advantageousfeatures as hereinafter set forth.

a fuel feeding aperture C entering the furnace,

` Above the bore F and preferably parallel thereto is a second bore having a small diameter cylindrical portion I andv a larger diameter cylinthe means for varlably timing the operating l small and large diameter bores I, I', said pistons being connected to each other by a rod M2.

the pistons M and M' impinging against the opposite ends of said valve form a lost motion actuating means therefor.

The hydraulic uid for actuating the pistons is preferably lsupplied by a pump of the type which maintains a substantially uniform discharge pressure with.a variable volume corresponding to demand. The specific construction of this pump forms no part vof the present in' vention and it is, therefore, merely indicated diagrammatically. As shown, the pump N is mounted on top of the block E and is connected by a suction conduit N with the bottom of the storage chamber or sump L.' A screen or filter N2 surroundingjhe lower end of said conduit serves to prevent the entrance of dirt o rdsediment into the pump. The discharge conduit 1W of the pump is connected directly to the chamber L' aso as to maintain in this chamber and also in 'the connected large cylinder portion I' a predetermined pressure, such for instance as twohundred and fifty pounds per square inch. With the construction as thus far described,

. it will be evident that the iluid pressure within the cylinder I' acting upon the two ypistons M and M' win through the differential areas thereof force said pistons'to the right. Figure 1, and will move the valve J to a position where fluid is admitted to the passage K and from the latter into the outer end of thecylinder F. This will move the piston G forward and through the rod H will move the ram B to its normal position beneath the hopperA. To retract the ram the drical portion I. Within the large diameter portion is a valve J which controls passages K ing upward on opposite sidesof the same within the block E is a storage chamber L for hydraulic iiuid. A second and separate chamber L' is formed within the block above the large diameter cylinder portion I' and communicating to the inner end thereof through a port I?.

M and M' are pistons respectively within the valve J must be shifted so as to admit` fluid through the passage K to the inner end of the cylinder F while the passage K leading to the outer end will simultaneously be connected to the exhaust K2 which empties into the sump or chamber L. For accomplishing such movement I have provided restricting means for admitting fluid to the cylinder I on the opposite side of the piston M'. This will slowly move the pistons M and M to the left, Figure l, and near the completion of the movement the piston M impinging against the valve J, will shift the latter. Any leakage-of fluid past the piston M will escape through the drain passage K. During the interval in which the pistons are moving prior to contact with the valve, the ram remains stationary in its forward position. When, however, the valve is shiftedthe ram will be quickly retracted. A reshifting'of Vthe valve to its original positioniis then accomplished by exhaustingthe fluid forward of the. piston M', which in turn is effected by a valve O having its operating stem extending into the path of the ram. As shown. this valve is locatcdin a casing P at the forward This .rod passes through a bearinginl the valve J while ative, for at the completion of the time .inte

end of the block E, a spring O' normally holding the valve to its seat and the stem O* being actuated by the ram to unseat the valve. An exhaust port P leading to the sump is opened by the unseating of the valve with the result that the pistons M and M quickly move forward under the actuation of the differential fluid pressure.

Thus, the valve J is restored to its normal posi- 4 tion in which uid is admitted to the outer end lof the cylinder F to drive the piston G and ram B forward, which completes the cycle.

From the description given, it will be evident that th length of period of rest of the ram is dependent upon the degree of restriction which controls the rate of fluid flow into the right hand end of the cylinder I', and consequently the time required for its movement rearward into contact with the valveJ. On the other. hand, the speed of operation of` the ram is determined only by the fluid pressure, the size of the ports and passages and the resistance to be overcome. It is, therefore, possible in designing the construction to have the ram always operate at a desirable speed and at the same time to control the fuel feed by altering the length of intervals between successivev operations. For such control I preferably employ a regulating valve Q, which is placed in a conduit R leading from the conduit N? to the valve casing P, which latter has a passage P extending to the right hand end of the cylinder I. The valve Q may be oi any suitable construction by means of which the ilow of fluid therethrough may be graduated, sodzhjat by shifting the actu-k ating handle Q"'e operator may increase, or decrease -the timiifg as desired.

In the operation of a stoker it sometimes hap-1 pens that the fuel feed will become clogged so as to endanger breakage of parts. Usually this is guarded against by the use of a shearingv pin in some portion of the mechanism, which in case of an overload will be severed. rendering the apparatus temporarily inoperative. With my construction the maximum actuating force is determined by the constant iiuid pressure and the area of the piston in the hydraulic motor, this force being" limited to avoid danger of breakage. Thus, should an obstruction to the fuel feed occur before completion of the forward stroke of the ram further forward movement will be arrested..

However, this does not render the device inoperl the motor land ram will be moved rearward and then forward again to the same point. In other words, instead of completely stopping the fuel feed the stroke of the ram is merely shortened.

What I claim as my invention is:

1.,'In a stoker, the combination with a fuel feeding ram, of a reciprocatory hydraulic motor 'directly connected therewith to retract the ram Yby its rear stroke and tdfeed the fuel by its forward stroke, means for supplying fluid to said motor at a substantially constant predetermined pressure, a v ve :controlling the reciprocations of said motor automatically quickly reversed at the completion of said rear stroke, a member actuated by hydraulic ressure having a lost motion connection to sall valve, means operating at the beginning of the forward stroke of said motFor for supplying the actuating nuid tosaid member to move it in one direction, means for moving said member 1n the other direction, and adjustaasaecs able means for regulating the rate of supply and thereby controlling the timing of successive cycles of said motor and ram.

2. In a stoker, the combination with a fuel feeding ram, of a reciprocatory hydraulic motor directly connected therewith to retract the ram by its rear stroke and to feed the fuel by its for- -ward stroke, means for supplying fluid tov said motor at a substantially constant predetermined pressure, a valve for controlling said motor,

hydraulic actuating means for said valve havinga lost motion connection therewith and normally Fheld by differential pressure to position said valve for vthe forward movement of said motor, means automatically operating upon the beginning of the forward stroke of said motor for supplying fluid to said hydraulic actuating means so as to reverse the differential pressure thereon and to ,effect a movement thereof in the opposite direction, means for regulating the rate of supply to time the interval for taking up lost motion and actuating said valve so as to cause a rear stroke of said motor, and means operating upon the completionoof said rear stroke for exhausting the fluid from said regulated supply to again reverse the differential pressure on said actuating means, whereby said valve is quickly reversed for the forward stroke of said motor and ram. 3. In a stoker, the combination with a fuel feeding ram, of a reciprocatoryhydraulic motor directly connected therewith to retract the ram by its rear stroke and to feed fuel by its forward stroke andy controlling means for said motor comprising aligned communicating cylinders of different diameters, connected spaced pistons in the respective cylinders, means for supplying to the space between said pistons hydraulic iluid at substantially constant pressure, a valve located in the space between and having a lost motion connection with said pistons, said valve controlling ports to the opposite ends of said motor, the differential area of said pistons `normally holding said valve in a position for `the forward stroke of said motor, means for supplying fluid `to said 4large cylinder on the opposite side of said piston to move the same in reverse direction, means for regulating the rate of iiowof the supplied fluid to vary the interval in which lost motion is taken up and said valve is actuated. a pilot valve opened st the completion of the rear stroke of said motor for exhausting said supplied fluid and to permit the quick operation of said pistons to reverse said first mentioned valve. and means for closing said pilot valve at the beginning ofthe forward stroke of said motor and ram.

4.' In a stoker, the combination with a fuel feeding ram, of a reciprocatory hydraulic motor directly connected therewith to retract the ram by its rear stroke and to feed the fuel by its .forward stroke, means for supplying fluid tosaid motor at a substantially constant predetermined pressure, a valve for controlling said 'motor, means for quickly reversing said valve ,at the completion of the rear stroke of said motor for eifecting a forward stroke thereof, and means operating after a predetermined time interval from the beginning of the forward stroke of said motor for again reversing the valve to cause a rear stroke.

ROYCE L. BEERS.

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