US235748A - Safety-valve - Google Patents

Description

(No MoideLl, 2 Sheevts--Sheqt'a l' J. E. Cms?. Safety Vlve. N0, 235,748. Patented DBC. 21,1880.

N. PETERS. FMOTG-LITHOGAPHER. WASHINGTON. D4 C. "f

UNrrnD STATES PATENT Carien.

JOSEPH E. CRISP, OF BOSTON, MASSACHUSETTS.

SAFETY-VALVE.

SPEGIFICATIONforming part of Letters Patent No. 235,748, dated December 21, 1880.

- Application led August 30, 1880. (No model.)

the line m of Fig. 1. Fig. 4 is a vertical sec-- tion of the valve, representing the position of the parts whgn the valve is open or blowing. Fig. 5 is an elevation of the main piston. Fig. 6 is an elevation of an auxiliary piston and its attachments, with-the exception ot' the weight or load.

This invention relates to a safety-valve in which a weighted auxiliary piston or slide-valve controls the operationof the main piston orvalve by being actuated by the excess of pressure in ,the valve-chamberto open aport and close an exhaust, whereby the pressure in the valve-chamber is allowed to enter a chamber below or at one end of the main piston and lift it, thereby openin g a direct passage from the valve-chainber for the escape of the excess of pressure, and by the diminution of pressure in the valvechamber to the required pressure, or a pressure slightly below the required pressure, to close the port and open the exhaust, whereby the pressure in the side chamber below or at one end of the piston is allowed to escape and the main piston is moved by the pressure in the valve-chamber to close the direct passage.

In the drawings, A represents the valvecasing 5' a, the valve-chamber 5 c', the passage by which it is connected with the boiler or vother pressuregenerator; e2, the direct escape port or passage from the valve-chamber; a3, the main piston, which has two heads, a4 a5, of unequal area, the area of the head c5 being somewhat less than that of the head a4; as, a projection from the head a4; a7, a portion of the valve- .asing surrounding the part a6 ofthe main pistzn. ,Y

The rw .n piston a3 has ahole, b, and a charn- 5o mi the reception of the auxiliary piston B, the piston-rod b2, and the weight b3, which is carried by the piston-rod, and is secured thereon in any desirable way.

A passage, b, extends from the valve-chamber a. through the main piston to the small annular chamber b5 between the two heads of the auxiliary piston B. The part bi ot' the piston-rod, or spindle/7 as I prefer tonarne it, is reduced in size to provide an annular channel, b", between it and the wall of the hole b below the lower head of the piston, and which, when the piston is lifted, as hereinafter explained, permits the steam to pass through the passage b4 into the chamber c below the piston-head a4, also connects the auxiliary piston B with the valve-disk c2, which, with the seat c3, controls the exhaust-passage c extending from the chamberc downwardly through the projection as ot' the main piston.

The auxiliary piston and its connection are fitted very loosely'in the hole b and chamber b', and they, together withthe wall of the said hole and chamber, may be nickel-plated, if desired. This or vsimilar provision should be made to reduce the amount ot' friction between the parts to a minimum, also to prevent the possibility of corrosion.

It will be observed, also, that the area of the upper head of the auxiliary piston is enough greater than that of the lower head to allow the ordinary pressure to lift the piston and piston-rod, but that the difference in area is not suflicient when the piston is loaded to allow the ordinary pressure to lift the piston and its load until the pressure in the chamber c exceeds the required pressure; also, that by proportioning the area of the two heads so that that ot' the upper head shall be a trifle the greater a very light load only is necessary to keep it seated at ordinary working pressure, while if the area be considerably larger a heavier load is needed; also, that the movement of the auxiliary. 'piston B and its load by the excess of pressure in the valve-chamber not only opens the passage to the chamber c,

but also closes the exhaust, and that the exhaust-passage remains closed during the upwardmovernent of the main piston to open the valve for the escape of pressure as the auxiliary piston moves with, it, and that while the IOO valve is blowing and after the pressure has been reduced sufficiently the auxiliary piston B falls and closes the passage b4 and opens the exhaust, and that then the pressure on the lower piston-head causes the main and auxiliary pistons to move downwardly to their original position.

As the head a4 of the main piston is greater in area than the head a5, it follows that upon the opening of the exhaust and the closing of l the passage' between the chambers a and c the main piston will be returned to its original position by direct pressure from within the valve-chamber acting upon the head having the increased area with somewhat greater power than it acts upon the other head.

A drip-passage, c4, extends from the bottom of the chamber b downwardly through the projecting portion a5 of the main piston to the passage c5.

In order that the steam may pass freely into the chamber c, I groove the under side of the piston radially from the annular channel bl. rIlhe amount of pressure required to lift the weight b3 is varied by increasing or decreasing the weight or by varying the size of the chamber b5 or the area of the heads of the auxiliary piston.

In lieu of a dead weight aspring or weighted lever may be employed. Any suitable packing may be used for packing the joints between the piston-heads and the valve-casing, and I represent in the drawings a metallic packing, d, consisting of the ring d', of sheet or other metal, shaped to fit the bore of the cylinder or valve chamber, and having a an ge, d2, by which, with the aid of the nut cl3, itfis fastened to the piston-head.

The interior of the rin g is cup-shaped, and pressure upon it extends it against the wall of the cylinder. The piston-head a5 has wings a8, which give it a bearing against the valvechamber or cylinder when the piston-head has been lifted to yopen the escape-port.

Generally the piston lifts until it contacts with the bunter e on the lower side of the top diaphragm or plate, E, of the valve-easin g, and the casing is enlarged at its upper end above the piston-head in order to provide for the escape-passage a2.

The weight b3 should exactly balance the maximum pressure described, and any excess of that pressure will immediately lift the auxiliary piston-weight and spindle, thereby enabling the pressure to pass into the chamber below the main piston. y

Any packing of a suitable nature may be used about the heads of the auxiliary piston B, and I have shown grooves or recesses f extending around the piston-rod and spindle for providing what is known as air-packing.7

Of course the passage into the chamber c is not opened until the piston'B has lifted the spindle sufficiently to bring the upper end of the port b7 inline with the lower end of the passage b4.

I do not confine myself to the location of the slide-valve or auxiliary piston in relation to the main piston described; but it may be located `outside the valve-chamber a, and be adapted to operate the main piston substantially as herein described, in which case the passage b4, instead of passing through the main piston, would pass fromthe valve-chainber into a chamber corresponding to the chamber b5, located outside the casing A, and containing the auxiliary piston and devices for operating the exhaust, and upon the upward movement of the auxiliary piston a passage would be opened into the chamber c in the main valve.

The operation of the valveis as follows: The piston-rod b2 is loaded by a weight which determines the amount of pressure in the valve-chamber required to lift the auxiliary piston B, and the excess of pressure in the chainber b5 over the balanci ug point causes the auxiliary piston and weight to lift sufciently to connect the passage b4 with the port b7 and to close the exhaust-passage, thereby allowing the pressure in the valve-chamber a. to pass into the chamber c below the piston-head 1,4 and to force the main piston upwardly sufficiently to allow the escape of pressure directly from the main chamber of the valve around the Lipper head, a5, through the direct passage or port a3. Upon 'the reduction of the pressure in the chamber b5 the auxiliary piston automatically returns, closing the passage b4 and opening the exhaustrc, whereby the steam in the chamber c is allowed to escape and the piston is returned to its original position by the pressure within the main valvechamber, as hereinbefore indicated,

The area ofthe inlet a should ber somewhat smaller than that of the escape-passage a2, in

when the valve is blowing may be lower than in the boiler.

Having thus fully described my invention, I claim and desire to secure by .Letters Patent of the United Statesl. In a safety-valve, an auxiliary doubleheaded piston, the auxiliary valve-chamber b5, and the passage b4, connecting the main valvechamber with the auxiliary valve-chamber, in combination with the double-headed main pis-t ton a3, the said valve-chamber a, and the passage a', connecting the valve-chamber a between the heads of the main piston with the boiler, all adapted to operate substantially as described.

2. In a safety-valve, the combination of the valve-chamber c, a double-headed piston, one head of which is of greater area than the other, and the passage a', connecting the valvechamber between the two heads of the pistons directly with the boiler, substantiallyras "and for the purposes descr c l.

3. In a safety-vall .e, the combination of the chamber a, the piston co3, having the pistonheads a4 a5, the passage a', connecting. the chamber between the piston-heads directly with the boiler, the-auxiliary weighted piston IIO B, the passage b4, the port 127, the chamber c, exhaust c', and its valves; substantially as and for the purposes described.

4. In a steam safety-valve, a Weighted auxiliary piston adapted, upon the excess of pressure in the ValVechaLnber, to open the port connecting the valve-chamber a with a chainber below the main piston, and to close the exhaust-passage to the chamber below the head, and upon the reduction of the pressure to close the port and open the exhaust, substantially as and for the purposes described.

5. In a safety-valve, the combination of a weighted auxiliary piston for opening the port connecting the valve-chamber with the charnber below the main piston, and for closing the exhaust-passage, and upon the reduction of the pressure to close the port and open the exhaust, with the chambers a and c and the main piston a3,"a ll arranged in relation to each other to operate substantially as described.

G. In a safety-valve, a valve-chamber having the steam-induction Way a and the steameduction Way a2, arranged in relation to the piston a3 as described, and the piston a3, having two heads of unequal area, controlled as toits operation in opening and closing the eduction-Way a2 by an auxiliary double-headed piston operating a slide-valve and exhaust and the pressure Within the Valve-chamber a between the two piston-heads, whereby an excess of pressure in the valve-chamber is employed in lifting the piston, and the direct pressure in the Valve-chamber after the reduction of pressure therein is employed in closing the valve, substantially as and for the purposes described.

7. The combination, in a safety-valve, of a VaIVechaInber, a, having the inlet a and outlet a2, with a double-headed piston, arranged in relation to the inlet as described, and provided with the passage b4 ,.the chamber c below the lower head ofthe piston, and an auxiliary piston controlling a slide-valve in a passa-ge between thetwo chambers a and c, substantially as and for the purposes described.

J. E. CRISP.

Witnesses F. F. RAYMOND, 2d, A. J. OETTINGER.

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