US68853A - peters - Google Patents

Description

N. PErERs. PHOTO LTHCGRAPHER WAsHmGToN D C @uiten- `taire gattnt @Hita EDWARD N. DICKERSO, OF YORK. Y; Letters .Patent No. 68,853, dated September 17, 186'?.

Be it known that I, EDWARD N. DIcKiznsoN, of the city of New York, have invented a new and useful Improvement in the Valve-Gear of -Steam Engines, of which the following is a description, reference being had to the accompanying drawings, making-a part thereof, in which-f- Sheets No. 1 and No. 2 represent a complete drawing, in two elevations, of my improvements, as applied tio a double-valve eightyone inch beam engine, together with a section 4of myl'improved dashpot. i

Sheets Nos. 3 and represents the details of the lifting and tripping apparatus of the steam-valves; and

Sheets Nos. 5 and 6, the details of the 1ockslmi`t for working the exhaust and steam-valves,v whose pecu. liarity is in its exhaust-valve arrangements. V

The sameletters are used to designate the saine parts on .the di'ercnt drawings.

The essential conditions lfor working steam advantageously in' a steam engine are these First.` That thc steam-valve should bc'opencd with intense slowness, so as to impose the strain' of the'boiler pressure upon the piston and its connections by degrees, instead of suddenly, as is usually done'; and the reason is, that if all'the pressure 4in the worldwere put upon an engine when at its centre, no power would result, because the rectilineal motion of the pistou is exceedingly small, at or near the centre,'for a compara tively-long arc of rotation, while the friction incident to the rotar-y motion of the shaft and crank-pin journals, under a great pressure, is exceedingly large in proportion, and` thereforev pressure on theV piston at orinear the centre is a loss of power, while, at the-same time, the consequence of opening the valve suddenly is to impart a'blow which develops heat in the journals by limpact, makes it necessary to key up the engine very close, to i avoid the jar incident to taking up the slack motion of the connections suddenly, and thus excludes oil,and in consequence indpces hot jouwrnalsand abrasion.l i

Second. That after the full boiler pressure 11a-sheen once imparted to the piston` gradually, and it begins to move rapidly, and thus create a demand for steam in the cylinder, then that the opening should be sui- 'ciently rapid and large to supply that demand without .wire-drawing the steam.

Third. That the steam-valve should be shut with intense rapidity when the time for ell'ecting the eut-o has arrived, so as to prevent any loss in wire-drawing the steam by slow closing. Y

Fourth. That the cut-oil` should bc accurate and uniform in its action, unaffected by the spring of the parts, or the diierent degrees of pressure or, lubrication. i L

Fifth. That the exhaust-valve should be opened before :the piston reaches the opposite end ofthe cylinder, ati'rom thirty to forty degrees of` the revolution of the crank, (varying with `the speed of rotation,)so that the time necessary for condensation shall be talt'cn while the piston is moving the least in proportion to the circular motion of the crank, and therefore while the least loss is sustained by withdrawing the pressure from it; `whle,. at the same time,.the exhaust-valve at the end et' the cylinder which the piston is approaching. shall be held open till thc piston reaches the end of its stl-olie, so that no retardationshall be sustained by compressing the steam and making a cushion under the piston. j

To comply with these conditions practically is the object of these improvements, and they do'eiect it to a degree much greater than ever yet was known in any steam engine. y

In the accompanying drawings, A represents the rock-shaft, which in this engine works all `the valves; but it may be made in two or four parts, according to circumstances, retaining the same mode of operation.' B is` a fixed lifter, permanently attached to the steam-lifting rod, which operates on the steam-valve stem V only through the intermediate agency of anotherlifter, C, which is loose upon the lifting-rod, and which depends upon the fixed lifting-rod and lifter B by the stud E, which rests upouthe lever L, :centred on `the fixed lifter B at`one end, having a fulerum, X, (which in this case `is the bonnet of the valve-obesa), to support -'its other end. The lever L is made adjustable by the screw I, whieb,being turned, shoves the block M upon which the lever L is centred, and which slides in a grooveA cut into the lifter B, so that the relative positions of the fulcrum, the centre of vibration, and Athe point on the lever where the upper lifter is supported, may be changed without changing the position'ot` the stud C in respect to the valve-stem, and, as a consequence, the speed of the initial lift'may bey altered at pleasure, so-as to admit thesteam to the cylinder-slowly enough to produce the desired result., The adjustment of this lever may be dispensed with, and the lever fixed permanently; but the result is not so goed.

By this arrangement :it is apparent that when the lifting-rod begins to risc the valve itself` and the lifter C Will rise much slower, since their motion is reduced by the inter-position of the lever between them and the fixed-lifter; but the speed ol openingz,r will be increased as the lover continues to rise and lo elongate the fulcrum, by bringing successive points into contact with its lower curved surface. llfhen, however, the lower lifter-B has overtaken the upper one C, by closing up the gap lel't between them, (whose width, in this case, is about two inches, and is measured bythelcngth of the stud EL) then the valve will continue to rise with ,the motion of the lifting-rod. The lever itself may be made long enough, and so shaped, as to. impart the increased motion without ceasing to act on the valve, which is the best way in fusi-moving engines. lhns the ilrs't and second essentials forworlting steam advantageously are complied with.

Tlf, machine called by its inventor, Mr. Sichels, a daslupot, 11s-'improved by me, accomplishes the third essential condition more oiiectually than ever before it was done. It is shown on Sheets No. 1 and No. and marked D. i

In Figures 1 and 2 itis shown, in connection with the vulves, set on three legs overhead the valves, and connected with the valve-stems by two suspension-rods and a cross-head underneath, which is the best arrange'-A ment ordinarily, although itrnay be placed otherwise for the salie of convenience. .y

Figure 3 shows .in a vertical scctionthe construction of this new i dash-pot g and Figure s", a section through the interior plunger at 1, 2.

Its peculiarity consist-s in having two cylinders, one fitting inside the other, having the arrcsting-plunger n fixed on the inside cylinder, of smaller diameter' than itself', whieh,by confining the fluid used in the chamber m, arrests the descent of the plunger, and so of the valve it controls. This machine is to be filled with. sonic iiuid, (water isthe bcst,) which may be done `through a hole in its top, fitted' with a cock or plug,-.and which Snpplies'the chamber m through the apertures ffii. If this machine is filled full of water, and well packed by the stuliing-box, the air will be excluded entirely, and, asthcinterior cylinder israised, an atmospheric vacuum is left under the plunger, which is therefore forced down with high speed by the pressure of thc air when released and allowed to drop. The size ofthe dash-pot in the drawinr is such as to make the pressure equal to about six hundred pounds, if full of water. Il? halt` full the pressure isless; land lthusany desired amount of spring pressure can be given to shut the valve with intenso speed, while the plunger below will arrest it in time to prevent damage toi'the valves, by confining the fluid with which it isi'filled in the chamber m, according to Mr. Sickelss great invention of the Siekels cut-ol.

To accomplish the fourth essential, Ihave invented a new tripping apparatus and a new mechanism for engaging thc valves with and discngaging them from the'l lifter by which they are opened. The first port consists in eentring the trippcr" ll" on the lifter which lifts the valve itself, so' that its action in trippingr is accurate and reliable; whereas, by the `old methods, in which the tripper was centred on some olhcr partei` the'engine than the lifter, the accuracy of its action was impeded by. thc .spring between the parts, and was niiected by the degree of lubrication.

The operation of this trippor will be seen in iig. 2, Sheets No. 1 and No. 2, where the tripper W is ccntred atc, and derives its motion from the ro'd s, which is connected to one end et the bell-crank Z1, and which is caused to vibrate by the'rod'r, which is connected to one en'd of the double bell-eranlt T, which is made to' vibrate the required distance, (which in this case is about eleven inches,) by attaching to the pin P a connectingrod, made to `nuove with the motion of the piston, or other desired motion, backward and forward, asy described by Mr. Sicltels in his patent of September, 1845, thus causing the tripper W to vibrate backward and forward through an arc of about forty degrees, and ,to pass at each stroke the roller or cum which it is designed to strike, and by which it operates to disengage the valve from the lifter. l The double bell-crank 'l is centred upon a sliding-block set in a vertical slot, and may be raised or lowered at pleasure by the handle Y, or any other suitable contrivance for adjusting` its position and by that means the point of cut-eil" is' varied at pleasure with great uniformity. This tripping apparatus may be made to worlc in combination with any method for engaging and disengaging the valves.

My new detaching apparatus is shown in detail in Sheets Nos. 3 and 4, where- Figure l represents a section of the apparatus in working order.

Figure 2, a plan of the same. v i

Figure 3, an elevation of it from the engine-room'.

Figure 4, a side elevation, and a halfisection, inthe same drawing, of the collar; and

Figures 5 and 6, a plan and sidel elevation of the vibrating die;

S is a circular collar, with a number of radial ribs projecting from it, running from Vend toend, parallel with the central axis,l between which channels are left, separating the ribs, which are marked g g. This collar is slipped over the valve-stem, which it surrounds at a free distance, so as not to bind it, and is heldin its vertical position by nuts on the valve-stem above and below it, 7c 7c. When in position this collar must be preventedfrom vibrating around the valve-stem, which is donc by a dog fixed to the lifter andprojecting into one of tho channels. This collar is small enoughin external diameter te pass through a hole in the lifter, which 'is made to receive it, so that the lifter may be raised above it if need be. The vibrating` die R has radial projections, pointing towards its centre, which correspond with the channels inthe collar S, but are narrower than they are, -so that it can be slipped down outside of the collar, with the interior projections enteringy the channels of' the collar, and so brought to rest in a recess formed in the lifter C to receive it, as shown in iig. l, in such a relative position to the circular channel t which is cut roun'd the collar S that it can turn freelyin that channel around the collar S. .The outside odge of a segment of the vibrating die is cui; with teeth, and a rack, I, is made to fit into them, on which the roller L is ixed, so that when the rack is moved endwiseithc die it is caused to vibrate; but other means of turning it may be used. '.lhe position in which the die R is set when at casse 3'- rest is such that its radial projections are ,under` the ribs q g of the collar S, as shown in plan at iig. 2, so that when the lifter is raised it carries up the die R, and with it the collar S, and the valve-stem and valve attached to it. But when the roller L is moved it vibratcs the die It, so as to bring its radial projections to agree with the channels in the colla1` S; andthe collar being no longer supported, will slip down through the lifter, and so close the valve and produce the cut-oil'. When the lifter returns to its lowest position again, it brings back with it the d-ie R, and as soon as it passes into the circular channel t the spring K'forccs the rack b back again, and so brings the die R under the ribs g g, ready for another lift. y

The peculiarity of this engaging and disengaging apparatus is that the moving part of it vibrates around a centre, instead of moving in sonic other direction, in reference to the valveste1n, whereby a uniform lift of the valve can be got, much greater surface to endure the abrasion at the instant of tripping, and much greater accuracy in the time of tripping. One or more projections may be'uscd, but for heavy valves the more the better. On large single valves, tov cut off short, I should recommend the use of twenty inches of length ol' edges in contact at the instant of tripping.

By these improvements inthe tripping'apparatus the fourth essential condition is secured.

Sheets Nos. 5 and 6 exhibit indetail the rock-shaftA, as shown in operation in the general drawing in Sheets Nos. 1 and 2. When the exhaust-toes are in working position, as shown bythe red lines, the valves will be operated as necessary to produce the eiect described; and on Va beam engine made from these drawings the eccentric would be set with alead of about twenty degrees in advance of the line of thecrank on the shaft, so that one exhaust-valve would be open about two inches whenthe piston reached the end ofthe stroke, while the other one would Vclose nly when the piston had reached the end of the stroke. If the engine has to bc worked by hand, however, by the use of a trip-shaft, then one of the exhaust-toes must be dropped out of thc way, or both exhaust-valves will be open at the same time, and the engine cannot be moved by the trip-shai`t.

To e'ect this improvement in the manner of removing this toe is the object of this part of the improvement,-

and it isdone by having one ofthe exhaust-toes F loose on the shaft, so that it can be vibrated a short distance around its centre, while a permanent toe, W, supports the foot of the stud U, which is set on a centre in a recess made in the toe W, 'and which can be turned to drop into that recess by the handle H, so that the toe which it supports may fall to the level of the top of the toe W, and thus come down so low as to permit the lifting-rod to close the exhaust-valve. In that situation the engine can be worked by hand by the trip-sln'ri't.`

Of course these improvements are applicable to all sorts of engines, and all sorts of` valves, where the steam-valve is independent of the exhaust and is to be tripped. p

What I claim as my invention, and desire to secure by Letters Patent, isp 1. The combination of the two lifters on the same lifting-rod, one being fixed to it and the other sliding upon it, for the purpose of eiecting the reduction of the initial mot-ion of opening steam-valves, substantially as described.

2. I claim the combination of the lever for opening the steam-valve gradually with the fixed and movable.,

lifters, the one being-moved by the motion of the lifting-rod, and the other snpportinga separate disengaging apparatus, substantially as described.

3. I claim a lever, one end of which is raised'by the fixed lifter on the lifting-rod, and byiwhich the steamvalve is pricd -open gradually, so arranged that it can be adjusted to vary the speed4 of lifting without changing theposition of the point onthc lit'ter relatively to the valve-stem to which the lifting power is applied, substantially as described.

4. I claim the vibrating tripper, centred upon the lifter itself which opens the valve, as distinguished from a tripper which is vcentred on some other part of the machine, substantially as described. i

5. I claim the vibrating die for engaging and disengaging the.valve-stein, to effect acut oit', so arranged that it will vibrate in an are whose concave side is presented to the valve-stem, substantially `asdescribed.

6. I claim the collar which surrounds the valve-stem, havingone or more radial ribs upon it, forth'e purpose of co-operating with a movable die, to effect a cut-olf, substantially as described;

7. I claim a. dash-pot, .whose plunger is composed of two cylinders of unequal diameters, the smaller of which is the arresting plunger, forming the bottom of the larger one, and whose 'ex teri'or chamber is composed of a cup or secondary reservoir, to receive the arresting-plunger, and above it a confining vessel, to guide the` i larger cylinder of the plunger and to exclude the air, substantially as described.

8.I claim the combination, in a roclgshaft, of one false exhaust-toe, and one fixed one, by which it is supported, with a stud or prop between them, so arranged that it can be dropped or elevated at pleasure, substan4 i tially as described.

. In testimony Vwhereof I have signed my name to this specification before two subscribing'witnesses.

EDWD. N. DICK'ERSON.

Witnesses:

EDM. F. Bnown, CnAs. MoD. Bnown.

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