US1863020A - Valve - Google Patents

Description

Filed March 21, 1928 2 Sheets-Sheet l INVENTOR WEI/J 6- 0 4 6626 ATTORNEY June 14, 1932. J. c. MARBLE 1,863,020

VALVE Filed March 21, 1928 2 Sheets-Sheet 2 ATTORN EY Patented June 14, 1932 1 33% UNiTEc STATES; 1 PATE r Farce.

mgavrs emanate, or Moun'r VERNON, new YORK, ASSIGNOR To, AMERICAN V rnnorrLn COMPANY, L. on NEW YORK, N,.,Y.

VALVE Application filed' March 21, 1928. Seria1 No..263-,575.

This invention relates tomultipl'ee throttle A plurality of ports 15" having valve. seats; valves of-the type disclosed in United States formed at then: upper ClICIlIHfGIGIICGS: prof. Patent #1,662,955grantedMarch20, 1928 to vlde communicatlon between chambers Sandi R. M-. Brown, jand is in thenature of an 1m- 10, these ports being controlled by. poppet 5 provement; upon such valves. valves 1 6 having upwardly extending stems:

' In the type of throttle valve with which guided. 1n the caps 17. the present invention is concerned, dilficulty In allgnment with each of'tlievalve ports has been experienced in the operation under 15-inpartition 8 aretlie ports'18in-partition' certain Conditions which produce a state of 9, these ports being substantially of the-sanie 1o unbalance of the valves, tending: to malie dlameter as the ports 15.- The partition 9 them fly open and either throwing a straln around each of these ports is thickenedsoon the throttle-operatingmechanism lf'there that the walls of'the ports 18 formshrt openis a fixed connection between the valves and? endedcylinders, the-upper portions of'which such .mechanism, or causing the valves to areprovided-with a pluralityofvertical slots 1 jump away from the-lifting'mechanism when: 19 extending for some distance below thetops the latter is not positively connected theretoofthe cylinders. The valves 16 are prov ded" The object; of the present invention 1s to w1th stems extendingthrough chamber provide an improved form of" the arrangeinto chamber 12, and' pistons 20 are either ment shown in the abovepatent in which. any attached to or formed integrally with the ac tendency of the valves to become unbalanced: valve stems, said pistons being a sliding fit is eliminated. Other and more detailed? obin the ports 18-. The lower ends of the valve jects of the invention will become apparent stems are provided with spaced flanges 211 from the ensuing description of a preferred between which the cam fingers 22- of cam; form illustrated in the accompanying drawshaft 23] are located. The cam shaft 23 is 25- ings, in which Fig. lis a fragmentarylongicarried through the end of the headerto the tudinal' section through a superheater headexterior of thefsmolte-box where it is attached er in which; the improved" form of valve is by means of' the operating lever 24 to any incorporated Fig. 2is a section through the suitable form of throttle rigging, not shown. header taken at right angles to Fig. 1 and As will be obvious fromFig. 2, rotation of Fig. 3 is a fragmentary section similar to the cam shaft 23 in a counter clockwise direc- Fig. 2 and showing anothenform ofval ve. tion will operateto open both the pilot valve Referring now to Figs. '1 and 2, the super- 14 and the main-valves 16, the arrangement of heater comprises a header casting-indicated the cam fingers 2 2'being such that the pilot generally at 1, located in the usual position valve is lifted from its seat first, thus placing within the smoke-box2 of'the locomotive and chambers 6' and 12 in communication and of the samegeneral form as: that shown in throughthe pressure exerted below pistons the patent referred to above. Steam enters 2O balancing the main valves 16. The main the saturated steam chamber lafrom the valves'16 are opened, preferably in succesboiler-dry-pipe 3', and after passing through sion as indicated in'Fig. 1, by further rotation, 9

'40 the superheater elements 4 located in the boilof the cam, shaft. o

er fiues is delivered through the passages 5 to As is to be particularly noted fromv Fig. 1, the chamberb of the superheated steam the location of the pistons 20 with respect to header 7. The header-7 is divided by longithe slots 19 is such that when the valves 16 tudinal: partitions 8 and 9' to form. the upperareseated, thepistons 20 close communication or inletv chamber 6 an intermediate outlet between the balancing chamber 12 and the chamber: 10 from" which the engine. steam outlet chamber 10, but as the valves are opened pipes 11 lead, and a lowerrclosed balancing the pistons 20 uncover the lower ends of the chamber 12; Chambers 6 and 12 are placed slots 19 to provide a passage connecting chamin; communication through the port 13 conber 12 with chamber 10 beforethevalves reachtr'olled by'pilot valve 14. p their fully Opened position.

' This feature of the construction constitutes the principal feature of the invention and prevents the tendency of the main valves to become unbalanced for reasons believed to be as follows:

Unbalanced pressures on the valves tending to lift them have been found to exist only in installations, notably in Mallet locomotives, where the volume of the steam pipes 11 between the throttle valve and the steam chests is relatively large. Where such conditions exist a relatively large volume of steam must be admitted to chamber 16 before the pressure therein is built up to a pressure of the same order as that existing in the inlet chamber 6 and the balancing chamber 12. Therefore, when the first main valve to be opened reaches the position substantially that as indicated by valve a, the chamber 10 is still at a materially lower pressure than the pressures existing in chambers 6 and 12. A pressure drop therefore existsbetween chambers 6 and 10 and when the valve is in its closed position or very nearly closed position, the underside of the head of valve 16 and the upper face of piston 20 are subjected to substantially the same pressure, i. e. the pressure in chamber 10, while the upper face of the head of valve 16 and the lower face of piston 20 are subjected to the same pressure, i. e. that existing in chambers 6 and 12. Under these conditions the valve is balanced.

However, when the valve is moved slight ly above the position shown for valve a in Fig. 1, the head of the valve is then entirely within the chamber 6 and above the line of pressure drop between chambers 6 and 10, which is substantially in the plane of the valve seat. Under these conditions both the upper and lower faces of the head of the valve are subjected to the same pressure, while the piston 20 is exposed on its lower face to the high pressure in the balancing chamber 12 and on its upper face to the pressure in chamber 10, which because of the relatively small amount of steam admitted through one partially open valve is still at a pressure materially below that in chamber 12. Obviously this produces a condition of unbalance in the valve 16 which, if unre trained, would be forced immediately to its fully open position by the steam pressure acting below piston 20. When the valve is held to the cam arms in the mannor indicated, the tendency of the valve to be forced wide open by the unbalanced steam pressure causes an undesirable force to be transmitted through the throttle. rigging, tending to force the latter to open throttle position, and unless this tendency resisted manually by the operator, the throttle will be forced open. If there isno positive connection between the cam and the valve stem, as in the form shown in the patent referred to, the unbalanced pressure will cause the valve to leave the cam and fly to full open position,

From the preceding analysis it will be apparent then that in the initial stages of opening the prior form of valve is balanced, but after reaching a certain opening this condition of balance in some instances ceases to exist and the valve becomes unbalanced. According to the present invention, this undesirable condition is eliminated by the provision of venting means by which the chamber 12 is partially vented to chamber 10 after the first main valve has been raised to a predetermined point where it would otherwise tend to become unbalanced. This venting of the chamber 12 not only tends to reduce the pressure therein but also assists in raising the pressure in chamber 10, thereby tending to equalize pressures on the pistons 20, but due to the fact that the valve 14 is opened, additional steam is admitted to the chamber 12 so that a pressure of some magnitude is always present in'chamber 12 even after one or more of the main valves have been opened to a point where the venting slots 19 are uncovered.

An alternative form is shown in Fig. 3 in which the piston 20' is provided with a number of arcuate recesses 25 which extend from the lower face of the piston to a point below the upper face thereof. In this form the ports 18 are not slotted as in the form heretofore described, and the venting of chamber 12 to chamber 10 is accomplished through the recesses 25 in the piston which provide a passage between the two chambers as soon as the valve is lifted to a point where the 1 upper faces of the recesses move to a point above the walls of the port 18.

It will be obvious to those skilled in the art that the form and arrangement of the apparatus herein disclosed may be varied considerably without departing from the invention, as defined in the appended claims, which accomplishes the desired object by changing the pressures acting on a valve balancing means before the valve is moved from a closed to a fully open position.

I claim:

1. In apparatus of the class described, a casing forming an inlet chamber, an outlet chamber and a balancing chamber, a valve controlling communication between the inlet and the outlet chamber and opening against pressure in the inlet chamber, a valve balancing piston between the outlet chamber and the balancing chamber, means for admitting steam to the balancing chamber, and means for venting the balancing chamber to the outlet chamber past the balancing piston before the valve reaches its fully opened position.

2. In apparatus of the class described, a casing forming an inlet chamber, an outlet chamber and a balancing chamber, alined ports providing communication between the inlet and the outlet chambers and theoutlet and the balancing chambers, a valve controlling the first of said ports and opening into said inlet chamber, said valve being provided with a balancing piston located in the second of said ports, means for admitting steam to the balancing chamber before said valve is opened, and means for relieving the pressure in said balancing chamber when once the valve has been moved fairly off its seat and before it is moved to fully opened position.

3. In apparatus of the class described, a

superheater header comprising a steam inlet chamber, an outlet chamber and a balancing chamber, a plurality of portsvproviding communication between said first two chambers and a plurality of corresponding alined ports providing communication between said last 1 two chambers, valves controlling said first named ports, said valves comprising balanc ing pistons controlling said last named ports and closing the same when the valves are in closed position, a pilot valve for admitting steam from the inlet chamber to the balancing chamber, means for initially opening said pilot valve, and means for subsequently opening said plurality of valves, said pistons being arranged to provide a plurality of passages connecting the balancing chamber and the outlet chamber before said valves reach their fully opened position. I

4:. In apparatus of the class described, a superheater header comprising a steam inlet chamber, an outlet chamber and a balancing chamber, a port providing communication between said first two chambers, a second port in alinement therewith providing communication between said last two chambers, a poppet valve controlling said first named port and opening into said first named chamber, said valve having a stem forming a balancing piston located in said last named port, the

lower circumferential portion of said piston being recessed and the piston being so located that when the valve is in its closed position the piston closes said last named port and I when the valve is lifted from its closed position communication is established between the balancing and the outlet chambers through the recessed portion of said piston.

JARVIS C. MARBLE.

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