US331858A - Balanced slide-valve - Google Patents

Description

(No Model.) QSheets-Sheet 2. D. A. WOODBURY.

BALANCED SLIDE VALVE.

Patented Dec. 8, 1885;

UNrTEn STATES PATENT @EEibE.

DANIEL A. woonnnnv, or ROCHESTER, NEW YORK.

BALANCED SLl DE-VALVE.

SEECIFICATION forming part of Letters Patent No. 331,858, dated December 8, 1885.

Application filed February 2, 1885. Serial No. 154,727. (No model.)

T0 aZZ whom it may concern:

Be it known thatl, DANIEL A. WooDBURY, a citizen of the United ttates, residing in'the city of Rochester, in the county of Monroe, in the State of New York, have invented certain new and useful Improvements in Balanced Slide-Valves for Steam-Engines, of which the following is a specification.

My invention relates to improvements in balanced valves of that class in which the valve works under a relief-plate.

The obj ects'of my improvements are, mainly, to obtain greater perfection in the fit of the valve, more convenient and certain means for securing accurate adjustment of the reliefplate, and to guard against accidental unbalanced pressure upon the valve; also to pro vide more directand effective means of relief from overcompression, thereby enabling the rate of expansion to be increased without risk. I attain these objects by the mechanism illustrated in the accompanying drawings, in which- Figure 1 is a transverse section through. the cylinder and steam'chest. Fig. 2 is a detail section through the re1ief-valve case and its chamber, showing the internal arrangement of the chamber and its relations to its surroundings. Fig. 3 is a detail section showing a modification in the manner of sustaining the weight of the valve. Fig. i is a horizontal longitudinal section through the steam-chest and its contents and a portion of the cylinder. Fig; 5 is a plan of the valve. Fig. 6 shows the lower or sustaining edge of the valve. Fig. 7' is a detail showing a method of restraining the relief-plate from horizontal. displacement.

Si milar letters refer to similar parts throughout the several views.

A. valve supported upon its edge, and this edge tightl inclosed upon three sides, is liable to be subjected to an unbalanced pressure up on its upper edge by a slight leakage from between the valve and its support-post, the bearing-surface of the valve, into the exhaustcavity, and thereby exhausting the steam to a greater or less degree over a large portion ofthe surface of this edge, and in that way leaving a corresponding portion of the opposite edge unbalanced. To prevent this, by maintaining at all times a circulation of live steam beneath the edge of the valve, I form the passages h h along the entire length on both sides, with numerous openings, 2' 2', through the support D, and forming channels k'k across this surface, thereby keeping up constant communication with the surrounding steam. Valves of this kind require great accuracy, both in the fitting and adjustment. The arrangement of parts, as shown, will be found to greatly facilitate in obtaining this in both particulars. The workingfaces of both the cylinder and valve being first brought to a perfect fit, then, with the valve in position, the opposite face of the valve and the edges of the supports D D may be scraped or dressed to a common plane. The face of the reliefplate, including the wedges, which are fitted into grooves or channels formed in the reliefplate for that purpose, are also reduced to a common plane. \Vith the parts. then all in position they will have a uniform bearing throughout, and a slight forward movement of the wedges E E will bring the whole pressure upon the relief-plate, or as much of it as may be desired, upon the supports. In order to gage the movement of the wedges with certainty and accuracy, openings are made through the end wall of the chest, through which screws are worked bearing up on the larger ends of the wedges, and by which they are driven forward. \Vhen once the proper adjustment is obtained, the wedges should be secured from further movement by inserting the dowel-pins o 0, or by other suitable means. The screws should then be removed, and the openings closed by screwing in the plugsR, as shown.

The valve is made somewhat trapezoidal in its transverse section, that the slight wear upon the working-faces may be compensated by that in the downward direction. This form, with the inclined side toward the cylinder, allows the steam-chest to overlap the end of the engine frame or bed M, as shown in Figs. 1 and 4., without increasing the distance between the cylinder and valve-face. It also admits of a larger exhaust-passage, O.

In the use of a lap-valve to perform all of the functions required foran automatic engine the exhaust must be released very early at short points ofcut oiiior very liberal provisions made against accidental overcompression. Relief-valves for this purpose should be so 10- cated as to make the passages for escape as short and direct as possible, and the resisting force should always correspond with theinitial pressure of the steam in use at the time. The location of the valves, as shown, meets both of these requirements. The passages being short and direct, andthe valve opening against the pressure of the steam in the chest, the resistance is always exactly proportioned to the pressure underwhich the engine is working. The valve-case S, beingfitted into the passage 9 by screw thread, is screwed in until the flange presses firmly upon the packing m, leaving the openings 1 y in position to discharge into the chamber K, thence into the passage J. The valve can be removed with out disturbing the case by unscrewing the cap N. The supporting-spring should not more than barely support the valve in place; and a little less, allowing the valve to drop slightly from its seat when the steam-pressure is removed, is better still. Any suitable form of valve may be used.

In balanced valves ofthis kind as heretofore usually made the exhaust-cavity a has been simply a rectangular opening extending through to the relief-plate. This allows the exhaust-steam to impinge directly upon the surface of the relief plate, wearing it away by attrition. The flow of the steam is also thrown into eddies and counter-currents.

In the device shown the exhaust-cavity a is in the ordinary D form, with the curved passages f andf opening into it from the opposite face, leaving the section G between for the protection of the relief plate. It will be seen that in this arrangement, the valve being in the position shown, the portion of steam which flows through the passage 2) and recess F escapes into the exhaust-cavity through the passage f. This passage, being curved, defleets the current toward the exhaust-opening O, and both currents, meeting at a, unite and flow in one unbroken stream. As it is not necessary that the section G fit tightly against the relief-plate, the surface may be cut away, as shown by the dotted line, if desired.

1 am aware that partial protection has been given by extending ledges toward the center from each side of the exhaust-cavity, carrying the outer current of steam along the surface of the relief-plate and allowing it to escape at the middle, (see patent granted to J. E. Sweet November 28,1882, No. 268,055,) but that device afiords only partial protection, as the steam flows in a confined channel in close contact with the surface, and the flow upon both sides is angular and unnatural.

A valve working under a relief-plate should be as thin as possible, in order to avoid inequalities of expansion as well as weight, and it is therefore important that the valve spindle be so attached as to ofi'er as little obstruction as possible to the inflowing steam. The

, mode of attaching the valve-spindle 61 shown offers but little 5 butit requires the adjustment of the position of the stufting-box P. For this purpose the opening through the wall of the chest N is made large, and the stuffing-box provided with a large collar or flange, p, and the shank 22 made long enough to receive the nut r and washer s,whieh is made of sufficient size to more than cover the annular space 20. By loosening the nut the stuffing-box is read ily moved along the face of the chest, as may be required. Then by screwing the nut down again it is secured in its new position.

In the valve shown the principal dependence for the prevention of leakage in the direction of its movement is upon the sections between the passages!) and j and b and j. The sides next to the passages 12 and b are always in contact with the exhauststeam and kept at a low temperature, while the opposite sides next to the passages j and j to a higher,- although varying,temperature. Consequently the expansion is unequal. far as practicable, the chambers c and c are made through the entire width of the valve, and thus kept constantly filled with live steam, thereby correcting in large measure the inequality which would otherwise prevail.

The relief-plate is kept from longitudinal movement by setting a couple of dowel-pins, e e, in that portion of the chest upon which the weight of the relief-plate rests. The up To correct this as per ends of these pins are flattened, fitting into channels cut across the edge relief'plate. Any other obvious means may be employed instead.

hat I claim as my invention, and desire to secure by Letters Patent, is

1. The combination ofabalanced slide-valve, supported upon its edge, with the supportingpiece, the passages h, openings 1', and cross channels it. substantially as and for the purpose described.

2. In combination with the valve B, reliefplate 0, and supports D D, the wedges E E, set in grooves or channels in the relief-plate, all being constructed and operating substantially as set forth.

3. In combination with an engine bed or frame having inclined sides, and with the steam-chest overlapping the same, a trapezoidal-shaped slide-valve resting upon its narrow edge, with the inclined side toward the cylinder, substantially as and for the purpose specified.

4. The combination, with a slide-valve performing the functions of both a distributing and automatic cut-off valve, of relief-valves located in the chambers K and K, these chamhers communicating directly with the interior of the steam-chest, and through the passages g and g with the steam-passages H and H, substantially as shown and described.

5. In a slide-valve working under a reliefplate, the combination of the passages b and IOC b, channels or recesses F and F, passages f 1 c and f, and plate G, substantially as shown and described, and for the purpose set forth.

justable stuffing-box P, fitted with an annularsages b and j and bancl j, substantially as and space, 20 '10, around the part V, all constructed l for the purpose set forth. zslgggggleratmg substantmlly as shown and (le- D. A TOODBURY 5 '7. In a slide-valve operated under a relief- Witnesses:

WV. J. CREELMAN, IRVING E. BOOTH.

plate, or otherwise similarly confined, the chambers G and 0, arranged between the pas- I

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