US1204666A - Piston-valve. - Google Patents

Description

J. M. KERN.

PISTON VALVE.

APPLICATION FILED ocT. II. IsI5.

' .197'- Toe/Yay.

JOSEPH M. KERN, OF OSWEGO, NEW YURK.`

PISTON-VALVE.

Specification of Letters Patent.

Patented Nov. 14. 1916.

Application tiled October 8. 1915. Serial No. 54,724.

To all fir/1.0m it `m ay conce/n Be it known that I, Josnrn M. KERN, a citizen of the United States of America. and resident of Oswego. in the county of Oswego, in the State of New York. have invented new and useful Improvements in Piston-Valves. of which the following, taken in connection with the accompanying drawings. is a full. clear, and exact description.

This invention relates to certain improvements in pistou valves of the double packing-ring type. commonly used in locomotives for controlling the inlet and exhaust Isteam to and from the cylinder of the engine. These pistons are usually provided with opposite cylindrical e'nd heads fitted with an easy sliding fit in the cylindrical sleeves of the valve chalnber. the central portion of the valve being of less diameter than the end heads to allow a free entrance of the steam into the receiving chamber of the valve case. while the end heads control the inlet and exhaust ports leading to and from opposite ends of the cylinder. each head being provided with a pair of split packing rings which are expansible under their own tension to maintain reasonably tight joints between the piston heads and guide sleeves in which they are movable, thereby assuring a more perfect cut-oil". and conserving the steam energy. One of the advantages of this type of valve is that Vit is automatically balanced by the steam pressure surrounding the central portion thereof so that the only appreciable friction is that produced by the expansive force of the packing-rings. and in order that the valve may Work with perfect freedom and with a minimum degree of friction and incidental wear, it is desirable that the outward pressure of the rings shall be just sutiicient to maintain a steam-tight joint amdY no more.

These packing 'rings are usually seated ,in

separate annular grooves in the heads of the piston and must, therefore have sufficient play to permit free expansive movement under their own tension in order to be effective. the inner rings of each set adjacent the ste'mrreceivinff chamber being commonly known as steam rings." while the cuter rings nearest the exl'laust chamber are commonly known as exhaust rings. With this slight clearanc-n of ine rings in their respective grooves for freedom of movement, it is evident #het .more or less of the steam. depending upon pressure, will find its way through the joints between the packing rings and valve heads tending to equalize the pressure both at the inner side and outer side of the rings and allowing said rings to exert their inherent pressure against the inner walls of the valve chamber or sleeves in which the valve heads are movable. This is particularly true of the inner or steam rings when they are regis' tered with the ports leading to the steam chest or cylinder of the engine. because the steam pressure is then exerted against both sides of the steam rings. tending to balance them. it being understood that the steam rings are nevel' exposed to atmospheric pressure, but are always under the pressure of the live steam in the valve chamber or in both the valve chamber and cylinder. On the other hand. the outer or exhaust rings are always exposed on the outer side to the relatively low atmospheric pressure. while their inner sides are `exposed to the higher steam pressure from the cylinder. This inequality of steam pressure on the exhaust rings tends to cause them to hind and excessively wear the shoulders at the outer sides of the corresponding grooves, which not only interferes with the free operation of these rings, but soon causes excessive leakage of the exhaust before the valve is sutliciently shifted to uncover the port leading t0 the cylinder. In addition to these objectionable features. another and more serious objection is that when either exhaust ring registers with its port, it is subjected to a crushing or compression stress equal to the pressure of the steam in the cylinder so that if the engine is running under full steam and the inherent expansive force of the ring is normal. the compression stress of the steam upon the ring Would exhaust its expansive force` to a degree depending upon the space between the meeting ends of the ring at the point of division, or the space between the ring and the bottom of the groove in which it, is seated, thus causing the premature discharge of the exthe exhaust ring begins to register with and while it is moving across the exhaust port, and at the same time to reduce to a minimum the outward end thrust of the exhaust ring due to the relatively high pressure at the steam end'and the low pressure atthe exhaust end of such ring, thereby protecting the'annular shoulders at the exhaust ends of said rings against excessive wear and further reducing the liability of premature exhaust or blowf Other ob'ects and uses will be brought out in the ollowing description.

In the drawings Figures 1 and 2 are similar sectional views of an engine cylinder and valve case showing the valve in different positions. Fig. 3 is an enlarged transverse sectional view through the valve case and valve taken vin the plane of line 3 3, Fig. 2. Fig. 4 is an enlarged longitudinal sectional View, partly broken away, of the detached valve. Fig. 5 is a perspective view of one of the exhaust rings."

Inforder that my invention may be clearly understood, I have shown a portion of a locomotive cylinder -1- and a piston 2 movable therein, in combination with a valve case 3- and a piston valve -4- movable in the valve case. This valve case is provided with a steam inlet -f5- adapted to be connected to any available source of steam supply and is connected to opposite ends of the cylinder by the usual ports 6- and -6-, said valve case being also provided with the usual exhaust ports -7- and -7'-. i

The steam inlet -5- communicates with a receiving chamber -8- which surrounds the reduced central portion of the valve lfor the purpose of balancing the same, said valve being provided with enlarged cylindrical end heads -9- fitted with an easy sliding fit in suitable sleeves lO- in the adjacent ends of the valve case 3.

Each head of the valve is provided with separate annular grooves for receiving suitable packing rings -11- and -12- which are divided through one-side at -l3 and are tensioned to expand against the walls of the adjacent sleeves --10- with suiiicient pressure to produce substantially steamtightjoints, the periphery of the heads of the valve being of just sufficiently less diameter than that of the bore in their respective sleeves -10- to prevent friction therewith and allow the packing rings lto perform their full function in preventing the passage of steam around the hea s.

The inner packing rings commonly known as steam rings are L-shape in cross-section with their narrower portions seated with an easy sliding iit in the grooves as -14rand their outer wider portions overhanging the portions of the valve heads at the inner sides of said grooves, one object of which iste j Fig. 2, and

, ed to bring the vinstead of compressi enable the rings to automatically balance under the steam pressure in the chamber -8- by impinging against the inner face `as well as the outer face of the overhanging rings.

The outer or exhaust rings to which my invention is more particularly directed are substantially rectangular in cross section and are fitted with an easy Sliding fit in their respective grooves as 142- in the heads -9-' and are provided near their inner edges with a circumferential series of relatively small radial openings l5- the purpose of which is' to allow the steam from, the cylinder to pass throu h said radial openings to the interior o the ring, but at the same time that it impinges against the periphery thereof so as to balance said rings and allo7 them to expand against the inner faces of their respective sleeves l0-- under their own tension, thereby reducing the friction to a minimum, and at the same time effecting a steam-tight joint to pr'event premature escaper or blow from the cylinder at the instant the valve is shifted to bring the inner face of the exhaust ring into registration with the adjacent port -6- or -6-, this balancing effect being continued as long as any portion of either exhaust ring is registered with the adjacent port -6- or 6'-. This particular arrangement of the circumferential series of apertures close to, but yet slightly removed from the inner edges of the exhaust rings, is very important, in that it allows the steam to enter the interior of the ring from the cylinders at about the same instant that the inner edge of the exhaust rings is registered with the corresponding ports, thereby establishing a balance of pressure inside and outside of the ring at a out the same instant that it be 'ns to register with 'the port during its shifting movement in opening said port'to allow the exhaust of the steam from the cylinder in advance of the moving piston 2- For example, assumingt that the piston is in the position at the le -hand of the cylinder, as shown in is about to begin its stroke toward the opposite end of the cylinder, at which time the valve -4- will have been adjustinner end of theright-hand exhaust ring l2- into registration with the adjacent port 6 so that the steam in the cylinder -1- in advance of the piston the ring against itsl own tension, and there y allowing the steam to escape to the exhaust around the periphery thereof, will enter the openings 15 and thus establish a balance of pressure inside and outside of the ring and allow the latter to expand a inst the inner walls of the sleeve -10i or effectively preventin the escape of the steam. This alance o pressure will be maintained as long 'as W

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