US600806A - scott - Google Patents

Description

W. H. SCOTT.

(No Model.)

ENGNB.

Patented Mar. 15,1898.

www! ma (No'Moael.) 2 sheets-sheet 2` W. H. SCOTT.

` ENGINE.

No. -600,806. Patented Mar. 15,1898.

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SPECIFICATION forming part of Letters Patent No. 600,806, dated March 15, 189B. Application iiled December 7, 189'l Serial No. 661,043. (No model.) Patented in England November 19, 1894,'No. 22,349;

in France October 25, 1895, No. 251,217,I in Belgium October 25,

No. LIii/657.

To all whom it may concern:

Be it known that I, WILLIAM HARDING SCOTT, electrical engineer, a subject of the Queen of Great Britain vand Ireland, residing at Gothic Works, Norwich, in the county of Norfolk, England, have invented certain Improvements in Engines Operated by Steam or other Expansible Fluid, (for which I have obtained a patent in Great Britain, No.22,349, dated November 19, 1894; in France, No. 251,217, dated October 25, 1895; in Belgium, No. 118,054, dated October 25, 1895, and in Austria,No. 46 657 ,dated February 24,1896) of which the following is a specification.

My invention relates more especially to engines wherein the distribution of motive fluid is eifected as described in the specification of British Letters Patent No. 1,135 of 1892 granted to me; and the object of my present invention when applied to such engines is to combine the advantages of such distribution withadditional advantages due to the use of short and direct ports and passages and such a symmetrical and compact arrangement of parts that distortion of the cylinder by unequal expansion and contraction is obviated and there is a minimum of radiating-surface. According to my present invention I employ a valve of the piston-valve type, arranged in the center of the working cylinder of the engine, and valvular and other arrangements, as hereinafter described.

I will describe my invention with reference to the accompanying drawings.

Figure 1 represents in vertical section the cylinder and valve portion of an engine constructed in Vaccordance with :my invention. Fig. 2 is a cross-section on the line 1 2, Fig. 1. Fig. 3 shows an arrangement for operating the valve, and Fig. 4 is a, diagram illustrating the movements obtained thereby.

A is the working cylinder, and B is the top cover thereof, and C is the working piston. The said piston is annular and has two or more piston-rods D D, placed so as to'leave the center of the cylinder clear for a lined casing E for the reception of the piston-valve F, the annular piston C litting around the said valvecasing E and sliding thereover, it being made steam-tight by packing, which may be pack- 1895.1To. 118,054, and in Austria February 24, 1896,

ing-rings applied in the usual way of applying packing-rings to pistons.

I will presume for convenience in the following description that the engine is a vertical steam-engine, and such an. engine is shown in the drawings; but it is to be understood that the invention is not limited to vertical steam-engines. The upper end of the valvecasing E is arranged so that the valve inside it puts at ,the proper times the upper part of the cylinderin communication with the steam boiler or receiver or other place from which the motive fluid is supplied. The pistons of the valve F are so arranged as to control the passage of motive uid through the ports and to allow it to pass through the valve-casing, as hereinafter described. I prefer to work the said valve from the connecting-rod of the engine by means of a bell crank or cranks and connecting levers or links or equivalent arrangements, as hereinafter described. I prefer to have separate ports for the motivefluid admission to above the piston `and for the transfer of motive fluid from above to below the piston and for the exhaust arranged at three dierent levels. The upper port or ports G is or are near the top of the cylinder A for the admission of motive Huid at initial pressure or from a receiver or its equivalent. The intermediate port or ports H is or are for the passage of motive fluid from the upper side of the piston into the center of the valve-casing. The lower port or ports I may serve both for the passage of motive duid from the center of the valve-casing to the under side of the piston and also for the exhaust from the under side of the piston,

which exhaust is opened by the same movement of the valve which admits motive fluid at initial pressure to the upper side of the piston. The reverse movement of the valve first cuts off the admission of motive fluid and later on closes the exhaust, and then opens communication between the upper and under sides of the piston. This communication remains open for a portion of the upward stroke of the piston. Then it isclosed,

either by the piston covering up the port or by the valve, the motive fluid above the pist0n is then compressed from terminal pres- IOO sure, possibly to a pressure nearly as high as the initial pressure, while the motive fluid below the piston is expanded and is not exhausted until the piston arrives nearer to the top of its stroke. The sleeve X is connected to the stem of the piston-valve F for the purpose of covering the ports I-I, so as to keep them closed until the piston reaches the bottom of its stroke, the said sleeve X uncovering the ports I-I at or just before the time that the ports I are uncovered by the valve. The object of this is to prevent waste by ineffective expansion ofl steam in the space inside the liner E between the pistons of the valve F.

In order to control the amount of motive fluid to be admitted, Figs. l and 2, I provide a movable slotted ring c, placed outside the valve-casing, so that the slots c2 in it can be made to coincide with slots in the valve-casing when full pressure of motive fluid is required; but it can be made to cover these slots, or partly cover them, to throttle the motive fluid as required by being moved around by a pinion c3 on the rod e4. The part of the valve-casing E which is situated inside the cylinder namely, the part from to yis preferably made separate from the part which is inside the cylinder-cover, so as not to interfere with the removal of the cover. To obtain the aforesaid distribution with a single valve, I operate the valve by means of a bell-crank lever K, Fig. 3, or its equivalent, worked from the connecting-rod L by means of a short link M. The fulcrum 7c of the bellcrank lever K is so arranged that the rod N of the said crank-lever which is linked to the connecting-rod L moves in such a path that the link M makes a much smaller angle with the connecting-rod at the top of the stroke of the piston than it does at the bottom of the stroke of the piston. This will be readily seen by reference to the diagram Fig. 4, where the lines which correspond to the bellcrank, the connecting-rod, and the link are marked with the same letters as in Fig. 3.

I is the point of the upstroke for steam admission, 2 the point in the downstroke for steam cut-off, and 3, 4, and 5 the points in the downstroke, respectively, for exhaust cut-off of opening for transfer of motive fluid from one side of the piston to the other and of the cut-off of such transfer, and 6 is the point in the upstroke at which the exhaust opens; but it is to be understood that I do not limit myself to these particular points of control. The effect of this arrangement of valve-gear is approximately the same as would be obtained from an eccentric if it were shifted during the first part of the revolution from a position of small angularity with the crank, so that the valve could give an early cut-off to one of larger angularity at a later part of the revolution so as to get a later closing of the exhaust, and if the eccentric were restored quickly to its original angularity with the crank during the last part of the revolution.

The motion can `be obtained with a single bell-crank by fixing the fulcrum of the bellcrank at the back of the cross-head slipper or slippers (not shown in the drawings) and a little above the highest point that the crosshead reaches.

The connecting-rod L is a double one, with a space between the parts. The upper arm of the bell-crank is then preferably arranged to be horizontal, or very nearly horizontal, at its mid-stroke and to terminate sufficiently above the cross-head pin to allow of its movement, the valve itself being driven from this point in the usual or any suitable way.

The link between the connecting-rod and the other end of the bell-crank is a short one. This motion is applicable to valves generally in which it is required to have an early cutoff of the motive fluid without affecting the exhaust detrimentally, whether the valves be arranged inside or outside of the cylinder, as by altering the arrangement of the bell-crank other arrangements of the bell-crank or its equivalent may be used that will give the same kind of motion to the link-for instance, the bell-crank may be pivoted on or nearto the crank-shaft. A slide may be used to control the motion of the end of the link.

In order to allow for the different expansions due to the different temperatures of the piston and the cross-head in an engine with an annular piston with two or more pistonrods, as described, I may provide separate and distinct cross-head slippers, one fixed to each piston-rod and overhung connecting-rod pins which work in these separate slippers, so that the slippers themselves can give in the bearings of the connecting-rod pins.

In order to allow of the-removal of the cylinder and valve-cover, I connect the admission-pipe to the cylinder itself, and as the passage to admit the motive fluid to the cylinder I prefer to arrange an annular space A2 between the cylinder and the outside casing A3 thereof, and into this annular space A2, I admit the motive fluid that is to work the engine by the admission-pipe attached at A4. I prefer to make this annular space A2 only at the upper part of the cylinder, so that only the upper part of the cylinder is jacketed by the motive liuid that passes through this space to the cylinder. The motive fluid is conveyed from this annular space to the valve that is in the center of the cylinder by means of a space P, formed in the cylindercover B, and I prefer to arrange this space P so that it makes a complete jacket to the cylinder-cover. The inside and outside portions of the cylinder-cover which include this space between them may be in one casting or piece or in separate castings or pieces.

The annular Ispace A2 around the cylinder can, if necessary, be drained by means of a cock in any suitable way at a lower point than that at which the motive fluid enters, and I preferably arrange so that the motive fluid has to go partly around the cylinder before IOO IIO

it gets into the space in the cylinder-cover. In this Way this annular space makes, When steam is used as the motive fluid, a very efficient steam-separator, and it, as Well as the space .P in the cylinder-cover, makes a very efcient steam-jacket.

The exhaust-opening is shown in Fig. l on the line of section for the sake of clearness, but in practice it Would be placed ninety degrees around the cylinder, one Way 'or the other, so as not to come in the Way of the piston-rods.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare thatwhat I claim is- 1. In an engine, the combination With the cylinder,of an annular piston therein, a va1vecase in said cylinder extending through the piston and provided With admission and exhaust ports, one or more ports intermediate the said admission and exhaust ports, a valve in said case, and means for operating said valve, the said ports being arranged so that motive iiuid is iirst admitted and cut ott in one end of the cylinder, and communication established between the spaces on oppositesides of the piston during a portion of the stroke away from the crank-shaft, the edge of said piston operating to close such communication as the piston nears the end of its stroke, substantially as and for the purposes set forth.

2. In an engine, the combination with the cylinder and piston reciprocating therein, the 3 5 crank-shaft and connecting-rod, of a valve and its operating-rod, a lever having an arm connected to the,-connectingrod by a link, and the-other arm connected to the valverod, said lever being fulcrumed so as to cause the connecting-link to make.` a smaller angle With the connecting-rod at one end of the stroke of the piston than at the reverse end thereof, substantially as and for the purpose set forth.

3. Inan engine, the combination with the cylinder and annular piston, of a central valve-case in said cylinder having admission and exhaust ports and one or more ports intermediate said ports, a valve in said casing, the ports being so arranged that motive fluid is transferred from one side of the piston to the other through the intermediate port or ports, and the edge lof the piston operating to close such communication as the piston nears the end of its stroke, with the connecting-rod and Valve-rod, and connections between said rods so arranged as to cause an early cut-off and late opening and closing of the exhaust.

In testimony whereof I have signed my name to this specification in the presence of tWo subscribing Witnesses.

JAMEs HENRYLSTUBINGS, P. A. THAULEss.

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