USRE3727E - Improvement in steam safety-valves - Google Patents

Description

` valv .UNITED STATES lP srnnfr OFFICE..

n n. nsncnorfr, 0F BOSTON, MASS., AssIGNnn or WILLIAM NAYLOR..

IMPRovEM ENT IN STEAM SAFETY-VALVES..

Specification inrlnng part of Letters Patent No; 58,962, dated October 16, 1866; patented in England, Junuin'y 21, 1864; Reissue No. 3,727, dutcd November 9, 11369.

'l'o all whom it may conot:

Be it known that I, WILLIAM NAYLoR, of 57 Mildmny Park, in the countyJof Middlesex and Kingdom of Great Britain, have invented'eertain new and useful Improvements'in SafetyfValves; and Ilherebydeclare-the following to be a free, clear, and exact description ofthe same, reference being had to, the accompanying drawing.

.This invention Arelalt-gs/ to spring ,safetyvalves, and is yapplicub to locomotive-en gine boiler's and stationary and marine engine boilers. l

The main object to be attained by this iuvention is the counteraeting the additional load upon the valve as it is Vraised frm its seat, produced by the increased resistance of the spring 'This is accomplished by using a lever of vthe first order, one fend resting, by-a suitable pin, upon the safety-valve, constru'etf ed and arranged as herehiafter described, and

' .the other end of `the4 lever resting upon the spring; but iii lien of having this lever straight,

or nearly so, I propose to bend downward that end which is acted upon by the spring to an ongle of about forty-tive degrees, so that when the vulve is raised by the steam the other end of the lever is depressed upon or against the spring downward, and at the same time is moved inward toward the fnlcrum, thus virtually shortening that end of the lever, and thereby connteractiugthe additional load upon the valve as Vit is raised. from its seat by the greater amount of compression or tension, as the case may be, whichis put upon the spring; and myinvention also consists in the valve C, constructed with projecting downward-curved lip or peripheryr and in the annular chamber' D, surrounding the valve seat, whereby,4 as the spring is compressed by the lifting ot'tlthe projectiuglip of the valve and the annu ar recess are available in causing anin-- creased pressure on the valve, and thus oven come the increased Vresista-nce of the spring, due to its compression, as hereinafter more fully set forth.

Figures 1 and 2 of the annexed sheet of drawings represent', respectively, a vertical section and front' elevation of a safety-vulve constructed according to my invention.

A is the 1u ain thoroughfare, leading directly from the boiler; B, a lateral branch or escape` passa-ge for a portion of the steam after it` Ihas passed the valve C. 'l make this vulve to project over the edges of the exit-passage A und to curve its proiecting edges slightlyr downward,v as shown in Fig. 1, so that the G, by the expansive force of the helical spring.

H, which exerts an upward pressure against the opposite end, a, of the lever. This end'a of the lever is bent downward to an angle .of about forty-ive degress, and is acted upon directly by the upperend of a rod or spindle, I, situated inside the coils of the spring H, and provided with a a e or collar, b, against which the upper endet the spring bears, the lower end of the spring resting upon a crossbar, K, through a hole-in the center of which the lower end ofthe spindle I is guided and is free .to move vertically.

If preferred, the rod or spindle I may be dispensed with, the upper end of ,the spring H 'being turned up to bear directly against the lever, while the lower end may either lie in a sunk bed in the cross-head or be turnedv down to form a. contact or center bearingpoin't.

Fig. 3 is a detail, showing a slight modification of the mode of fitting or adapting the spring or springs H.

a is the bent end of the lever E. (Shown in Fig. 1.) b is a nipple or'center point, which is pressed against the end a of the lever by one or more springs, H H'. The lower ends of these springs bear against a similar nipple or eenter .point, c, which rests in a countersink in the cross-head K, or in the end of 'an adjusting-screw, d, passing through the crossthe va1ve-casing,and through correspondi b0lt-holes near each end of the cross-bar v will be which is thus supported entirely by the two By tightening more or less the bolts L, by their nuts, the spring H maybe compressed to any desired extent between the eross-bar K and the collar or ila-nge b on the'spindle I.

The operation of the peculiar bent lever 1s as follows: So soon as the ,pressure in the boiler overcomes the resistance ot' the spring H, the valve is lifted, and certain extra conlpression is put on the spring. The increasing compressiorfot the spring during the' opening of the 'valve has a tendency, if no com' pensating means are employed, to check the full opening ot the valve, so as to afford an escape-critics equal in area to that of the pas sage A; but, by bending down the lever, as shown at a, the lifting of the valve tends to draw that end of the lever toward the fnlcrnm,

.thereby virtually shortening that end of the lever. Consequently the pow'er of the lever to compress the spring is increased in proportion as the val ve is elevated, or, in other words, the rsistance of the spring is proportionately diminished.

When the apparatus is properly constructed the resista-nce against the lifting of the valve will 'be uniform, or nearly so, in what ever position the valve may be.

Fig. .4 represents a vertical section of a twoncl l0cou1otive-boi1er safety-valve, wherein the spring` operates by tension in lieu of by compression, as in the previous arrangement. The same letters lor reference indicate the corresponding parts of those shown in Figs.

. 1 and-2.

A is the main thoroughfare from the boiler. B is the erit-pipe for the escape-steam; C, the valve itself, which is held down by one end of the lever E, working on the fulcrum F, and bearing at one end upon a rod or spindle, G, while its opposite end is bent downward, as shown at a, and is connected, by the knifeedged link I, with the lower end ofthe helical spring H, to which the link is hooked. The upper end of this spring,-` which is inclosed in a tubular casingv H', is hooked into the adjustable eye It, carried by the lower end of the adjusting screw-spindle L, which passes through a central aperture in the top of the casing, and is prevented from rotating by a key, fitting' a slotted keyway, extending longitudinally down one side of the screwspindle.

M is a nut or hand-wheel working ou the screw-spindle, by turning which the screw will be raised or lowered, and,v consequently, more orless tension will be put upon the spring and a corresponding load applied to the valvelever E. N is a'circular knife-edged index screwed to the top 0f the screwspindle; and 0 1s the graduated scale attached lo the nut or hand-wheel, for indicating the `load upon the valve per square inch.

'The valve, on being lifted, will elevate the corresponding end ol' the bent lever E, and depress the opposite or bent end, a', which more or less resisted bythe contractile power of the spring H; but the end a, on being de ressed, will at the same time be drawn toward) the fulcrum, thereby virtually shortening that end of' the lever and compensating fort-he increased resistance of the spring.

When the collar o f E reaches the top ol the casing no further loadv can be put on the valve, land thus any tampering with the valve -is prevented.

Fig. 5 represents a vertical section of a portion oi a iiveinch safety-valve, adapted for large marine or land boilers, constructed according to this invention. It is similar 1n all essential details to the smaller arrangement illustrated at Fig. 4, and the corresponding parts are indicated by corresponding letters of reference.

In safety-valves for marine boilers I prefer, however, to close steam-tight the bottom of the casing containing the helical spring H, by means of a. flexible diaphragm, P, of vulcanized india-rubber or other suitable material capable of withstanding the action f steam, whereby all access to the spring of salt-water thrown through the Safety-valve when priming, and injurious effect thereof upon, the metal, are prevented. This diaphragm is held at its circumference between the flanges of the springcasing and the valvecasing, while 'its center is nippcd between the annular end c of the link i and the shoulder f, which shouL der has a sqnareor hexagonal center boss, g, formed thereon, and fitting a correspondinglyshaped aperture in the top of the link I.

h is nut working on a screw in the center of the boss g, and serving to nip the diaphragm between the parts c f.

The valve-casingis of cast-iron, and the valve and seat are of gun-meta.l'.

Q is a small relieving-lever for easing the valve when requisite, its inner end 'projecting beneath the end of the safety-valve lever, as shown, while its outer end is connected by a rod for actuating the relievingdever.

Claims.'

l. The combination and arrangement, with the hereinbefore described safety valve, of bent levers of the first order and the spring or springs, in the manner substantially as hereinbefore set forth.

2. The safety-valve C, with its overhanging downwardcurved lip or periphery and annular recess l),y substantially as herein shown. and described, and for the purpose set forth.

3. The annular recess I) surroundingthe valveseat, substantially as herein set forth.

4. The combination of the valve (l and the anuularrec'ess D, as herein set forth,'and for the purpose described.

WM. NAYLOR. Witnesses EDWIN 1. ALEX/innen, Trios. I. Brunn,

47 Lncolns InuFe'eIds.

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