US344881A - J thom - Google Patents

Description

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VALVE FOR ENGINES.' No. 344,881. Patented July 6, 1886.

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3 Sh t -Sh t 3. E J. ee s ee VALVE FOR ENGINES.

No. 344,881. Patented July 6, 1886.

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VALVE FOR ENGINES.

EtPECIFICATION forming part of Letters Patent No. 34.4381, dated July 6, 1886.

Application filed September l, 1885. Serial No. 175,870.

(No model.) Iatented in England August 23, 1F83, No. 4,087, and

in France November 21, 1883, No. 158,703.

To aZZ whom t may concern:

Be it known that I, JOHN THOM, a subject of the Queen of Great Britain, and a resident of the town of Barrow-in-Furness. in the county of Lancaster, in that part of the United Kingdom of Great Britain and Ireland called England,

engineer, have invented certain Vnew and useful Improvements in Valves for Steam-Engines, (and that the same has not been patented to 1Q me or to others with my knowledge or con sent, except in the following countries, to wit: in Great Britain by Letters Patent No. 4,087, dated August 23, 1888, and in France No. 158,703, dated November 2l, 1883;) and I do i 5 hereby declare that the following is a full, clear,

and exact description of my invention, sufficient to enable others skilled in the art to which it appertains, or with which it is most nearly connected, to make, use, and put the same into 2o practice, reference being had to the sheets of drawings, making a part of this specification, and to the letters and hgures of reference marked thereon,which correspond with those used in the specification, like letters and iigures being used to denote the same or corre` spending parts throughout the various views and gures.

My invention has for its object, among other things, to so construct valves for steaxn-en 3o gines that I obtain a large opening for the exhaust with a short travel of valve and to provide a means for utilizing a portion of the steam from one side of the piston at the end of the stroke for use at the other side of the 3 5 piston, the features of novelty being designated in the claims concluding this specification.

In the drawings, Figure 1 is a sectional elevation of a single-ported steam and double ported exhaust slide valve, and valveface, showing the valve at the top lead," and showing the means which I employ for conveying and utilizing the steam from one side of the piston to the other. Fig. 2 is a section elevation showing the valve with 4,5 the greatest Steamnpening. Fig. 3 is a sectional elevation showing the valve with the steam cut-o. Fig. 4 is a sectional elevation showing the valve at the point at which communication opens between the ends of the cyl-- 5o inder. Fig. 5 is asectional elevation showing the valve with communication full open between the ends of the cylinder. Fig. 6 is a sectional elevation showing the valve at the commencement of compression of the steam. Fig.. 7 is a sectionalelevation of the valve,

showing the point at which the exhaust opens. Fig. 8 is a sectional elevation showing the valve at the bottom lead.77 Fig. 9 is a sectional elevation of a slide-valve according to my invention of a 'single ported cylinder. Fig. 10 is a sectional elevation ot' aslide-valve according to my invention of a double-ported cylinder. Fig. 11 is a sectional elevation of a slide-valve according to my invention, being an ordinary. double-ported slidevalve, with my invention applied thereto. Fig. 12 is a sectional elevation of a slidc-valve ofthe piston type acccording to my invention. Fig. 13 is a section through X X, Fig. 12. Fig. 14 is a sectional elevation of a slide-valveof the piston type according to my invention provided with doubleported exhaust. Fig. 15 is a section through Y Y, Fig. 14C.

In practicing my invention I form a longitudinal passage through the back of the valve, the said passage being so arranged as to form a communication between the ends of .the cylinder, so that a portion of the steam from one side of the piston at terminal pressure is transferred from one end of the cylinder tothe other and used over again on the return-stroke. For example, thisvalve may partake ofthe nature of what is known asa trick-valve#7 butIso form the passage that a communication is opened through the passage of the valve from one end of the cylinder tothe other, so that the steam flows through the passage just before communication to the condenser is opened to one end of the cylinder and before new steam is admitted to the other end of the cylinder.

In the drawings, Figs. 1, 2, 3 4, 5, 6, 7, and 8 are sectional elevations of asingle-ported steam and doubleported exhaust slide-valve and valve-face, showing the means which I employ for conveying and utilizing the steam from one side of the piston to the other. These figures show the position of the slide-valve in relation to the piston. Upon reference to these figures, A. is the slide-valve; E, the cylinder valveface; G, a portion ofthe cylinder; D, a portion of the piston. The arrow E shows the direction of the pistons travel. al are the ly devoted to the exhaust.

v[1 0 point at which the exhaust opens.

exhaust-ports of the valve A, separated from the steam-inlets at the back of the valve A thatis to say, the steam enters only from outside of the valve A,while the inside is entirea is a passage through the baekpof the valve similar to the 1 passage in whatis known as the trickvalve;7 but the ports a2 a3 of the passage c are so arranged in reference to the ports of the cylinro der valve-face that the passage c serves to supply steam to the cylinder in similar manner to a trick-valve, and also to form a communication between the opposite ends of the cylinder C, so that a portion of the steam from one I 5 side of the piston at terminal pressure is transferred from one end ofthe cylinder to the other and used over again on the return-stroke. b b b2 are the ports inthe cylinder valve-face, the ports b serving for both steam and exhaust,

2c and the ports b b2 serving for exhaust only,

the port b2 being the main exhaust.

The working of the valve will be understood upon reference to Figs. l lto 8, inclusive, in which Fig. 1 shows the valve at the top A, lead steam being supplied in the direction shown by the arrows from the outside of the valve A and through the passage a,similar to ka trick valve. Fig. 2 shows the valve with greatest steam opening. Fig. 3 shows the Y3o steam cut-off. Fig. 4L shows the point at which communication opens between the ends of the cylinder C, so that the steam passes through the port a2 and passage c and port a? to the other end of the cylinder.- Fig. 5 shows the communication full open between the ends of the cylinder G.- Fig. 6 shows the commence'- ment of compression of the steam which has passed from one end of the cylinder to the other end of the cylinder. Fig. 7 shows the Fin'. 8 shows the valve at the bottom lead. a

Fig. 9 shows a slide -valve for a singleported cylinder with trick arrangement, and having negative lap on inside edge of the pas- 4 5 sage, forming communication between the ends of the cylinder.

Fig. 10 shows a slide-valve for a doubleported-cylinder with trick arrangement, and having negative lap 011 the inside edge of the 5o passage a', forming communication between the ends of the cylinder C.

Fig. 11 shows my invention as applied to an ordinary double-ported slide-valve with the trick-passage a so arranged as to have nega- 5 5 tive lap on the inside edges of the ports a2 a3.

The outside edges of the exhaust-ports a are made with a little larger positive lap, so as to prevent the steam from passing from the ports a2 or a3 direct to the exhaust a.

Fig. 12 shows a piston-valve and valve-face constructed with my improvements applied thereto.

Fig. 13 is a section through X X, Fig. 12.

Fig. 14 shows a similar' construction of valve and valve-face to that in Fig. 12, but

provided with double-ported exhaust.

Fig. 15 is a section through Y Y, Fig. 14.

l With reference to the drawings', A is the valve. .'B is the valve-face. l C arey the cylinder-ports. D is a portion o f the piston. c'is a passage through the valve having ports 0L2 a3. The passage a is in some respects similar to the passage in what is known vas a trick valve g but the ports a2 a3 of the passage c are so arranged in reference to the ports of the valveface, hereinafter' described, that the also to form a communication between the opposite ends of the cylinder, so that a portion of the steam from one side of the piston at terminal pressure is transferred from one end of the cylinder to the other and used over again on the return-stroke.

The annular chamber F round the valve A in Fig. 12 forms the exhaust-space. In Fig. 14. the annular chamber F forms the exhaustspace also; but in this case the exhaust-steam enters the chamber F by the circumferential passage F.

b b are the ports in the valve-face, the ports b serving for both steam and exhaust, and the ports b serve for exhaust only.

exhaust for both ends of the cylinder.

In operation the working of the valve will be as follows: Upon reference to Fig. 12, the

nication is opened between the ends of the cylinder, so that the steam passes through the port a2, passage a', and `port a3 to the opposite end of the cylinder. The valve, traveling port a3, and compression of the steam, which has passed from one end of the cylinder to the other, takes place. Soon after the passage a3 is closed, the exhaust is opened to the opposite side of the piston. has arrived at the end of the stroke, steam is admitted from the outside of the valve, and also through the trick-passage a', and the return-stroke is made. piston-valve is kept tight by packing-rings C, kept up with springs. y

On reference to the foregoing description, it will be seen that a valve according to my invention contains the trick arrangement applied to a valve having positive exhaust-lap at the top and bottom of the cylinder on the port-edges in connection with the condenser, and negative exhaust-lap between the top and bottom of cylinder on the passage through the ing a communication between the ends of the cylinder, just before exhausting, to the condenser, so that steam at terminal pressure is transferred from one side of the piston to the other, then compressed nearly up to the initial pressure, and used over again on the return-stroke. It can be arranged as a slidevalve or a piston-valve, and to suit single, double, and treble ported cylinders.

passage a serves to supply steam to the cylinder in a similar manner to a trick-valve, and

'Ihe annular passage b2 serves for the main valve is shown at the point at which commualong in the direction of the arrow, closes the.

When the piston..

valve, containedin one valve, thereby form- A valve constructed according to my inven-m tion saves in each revolutlon of the crank an' IOO The valve-face of the g amount of steam at terminal pressure equivalent to the capacity of the ports and clearance between the ends of the cylinder and piston, which in many euses is fully fifteen per cent. of the total capacity of the cylinder. As there is little steam left to compress in the lowprcssure cylinder with the ordinary slidevalve, if the vacuum is good and the ports large enough the work stored in the piston and other parts moving vertically is thrown away against the steam admitted by the lead; but by my invention the steam is taken from the other end of the cylinder after performing its ordinary work, and is compressed nearly or quite up to initial pressure, using the work stored in the piston and other moving parts for this purpose, so that there is no loss of power from changing the direction of the motion of the piston, and a greater number of revolutions can be got out of the engines with the same indicated horse-power.

The change of pressure from the one side of the piston to the other side being divided into four stages-(c) release by communicationopening; (b) compressing steam transferred; (c) exhaust opens to condenser; (d) initial steam enters-causes the engines to turn the centers without shock, even though the brasses are slack. The friction of the valve is reduced to a great extent through one part being always exposed to the pressureof the cylinder, thus tending to reduce the pressure on the valveface.

Having now described the nature, object, and purposes of my invention and shown how the same may be carried into practical effect, while I do not claim anything that is contained in the patent granted to John V. Vermillion August 24, 1875, what I do claim is l. In combination with the valve-seat of a steam-cylinder, a valve having a steam-passage communicating with the steam-ports at both ends of the cylinder at the same time, and a throat embracing' the exhaust-nozzle of the cylinder by which the valve in its motion upon its seat alternately permits the steam to pass from one end of the cylinder to the other, and then permits the engine to exhaust at the same time that a steam-port takes ste-am at two separate points in the same port, one leading through and the other around said valve, substantially as described.

2. A valve having a steam-passage which alternately establishes communication between the opposite ends of the piston-cylinder and then between the steam-chest and one side of said piston-cylinder, while at the same time direct communication between the steam-chest and the same side of said piston-cylinder is established outside of said valve, substantially as described.

3. The combination of a steamfchcst, pistoncylinder, suitable ports, and a valve with means for operating the same, said valve being provided with a steampassage which alternately establishes communication between the opposite ends of said piston-cylinder, and then between the steam-chest and one side of said piston-cylinder, while at the same time said valve admits steam to said pistoneylin der directly from the steam-chest outside of the valve, substantially as described.

JOHN TI-IOM.

Witnesses:

FREDERICK JOHN CHnnsBRoUGH, JOHN HAMILTON REDMOND, Both of l5 Water Street, Liverpool, England.

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