US479273A - Piston-valve - Google Patents

Description

(No Model.)

SHEY.

PISTON VALVE.

5 r W w I, a m 8 n 0 6m: 1 W\\\ Patented July 19 UNITED STATES PATENT OFFICE.

MARTIN E. HERSHEY, OF HARRISBURG, PENNSYLVANIA.

PISTON-VALVE.

SPECIFICATION fbrming part of Letters Patent No. 479,273, dated July 19, 1892.

Application filed April 11, 1892. Serial No. 428,681. (No model.)

T0 at whom it may concern.-

Be it known that I, MARTIN E. HERSHEY, of Harrisburg, in the county of Dauphin and State of Pennsylvania, have invented certain new and useful Improvements in Piston- Valves for Steam-Engines; and I do hereby declare the following to be a full, clear, and exact description of the same, reference being bad to the accompanying drawings, forming a part of this specification, and to the letters of reference marked thereon.

This invention relates to piston-valves for steam-engines, and particularly, though not exclusively, to that form in which two heads are employed with a steam-space between them.

The primary object of the invention is to provide a piston-valve which shall be capable of rigid adjustment to compensate for wear, whereby the adjustment is maintained throughout the stroke of the valve and while subjected to peripheral pressure in passing over the ports.

A further object is to provide a valve of this character which when the parts are cool will contract and prevent sticking or injury to the wearing-surfacesas, for instance, when the engine is started after a period of rest.

The invention consists in certain novel details of construction and combinations and arrangements of parts, all as will be now described, and pointed out particularly in the appended claims.

In the accompanying drawings, Figure 1 is asection,partiallyin elevation,throu'ghavalve constructed in accordance with my present invention. Fig. 2 is an elevation at right angles to Fig. 1, showing half of the head in section.

Like letters of reference indicate the same parts in both figures.

For the present purposes I have not deemed it necessary to illustrate the cylinders or steam-chest further than to indicate some of the parts in Fig. 1, for a purpose which will presently appear.

The letter A indicates the valve-rod, which directly or indirectly is connected with the usual valve-operating mechanism-such as an eccentric on the main shaft-and serves to move the valve in the ordinary manner. The portion of this valve -rod lying within the valve-chest is adapted for the reception of the head or heads which constitute the valve proper, preferably having clamping means such as nuts screwing directly upon the rod.

In the preferred construction I employ two heads-to form the valve, the casting or disk B constituting the body of one of which may, if desired, be secured permanently in position on the rod by being clamped against the shoulder or enlargement a, by the nut a,while the other disk or body B is held between two pairs of nuts a a which permit of its bodily adjustment longitudinally of the rod. Each body, or, as I shall term them, disk B, is provided with a relatively long central hub B, and a flange B located on one side a short distance from the periphery, the said flange being perforated or slotted at intervals for the passage of the radial arms 0 of the sectional spider. The edge or face of the flange is dressed for the reception of a faceplate or ring D, held in place by throughbolts d to form with the edge of the disk proper an annular or peripheral channel for the reception of the packing-rings E. These rings may be split or expansible rings of approved type, preferably, however, having laterally-projecting flanges overlying the peripheries of the disk and face-plate or ring, and being solid in cross-section, as shown.

The sectional spider, the arms 0 of which have been before mentioned, is composed of a series of radial segments formed by segmental plates O, underlying the packingrings within the peripheral channel, and similar plates 0 surrounding the hub B, while the arms 0 unite the plates and are guided at the outer ends in the slots before mentioned.

By referring to Fig. 1 it will be seen that the plates O are inclined, and together form a conical central opening, into which fits an expander, consisting of a sleeve F, working snugly on the hub B, and having a series of wedge-shaped radial flanges or ribs f, taking a bearing on the inner surfaces of the plates 0 Now ,it .is obvious that longitudinal movement of the expander will enlarge the diameter of the split spider by giving each segment a radial movement, and in order to move the expander lock-nuts H are threaded on the end of the hub B in position to abut against ZOO the face of the expander, as will bereadily understood. The inner edges of the plates C work against a straight surface 0 on the inside of the disk B and prevent movement longitudinally of the shaft when the expander is set up. The adjustment of the rings, it will be noted, can be made extremely fine, due to the double wedge formed by the screwthread and expander acting on the segmental plates C Hence the slightest'wear may be at once compensated for, and when the adjustment is made the parts are held absolutely rigid, the peripheral pressure of the steam as the heads cross the ports not atfecting the adjustment in the least, permitting ofthe use of the valve where the ports are large or extend a large part of or entirely around the inner circumference of the valvechest.

In all piston-valves as heretofore constructed, solid as well as adjustable, great difliculty hasbeen encountered by reason of the stick ing of the valve, particularly when the engine was started after the valve and chest had become cool and the parts had contractedythe result being that the wearing-faces of the valve and chest were cut and ruined, frequently requiring that theentire faces should be redressed' at great expense. Now I have overcome thisdilficulty eifectually by utilizing the diiferent rates of expansion of diiferent metals, whereby as the heads cool they are caused to contract in such manner as that pressure on the packing-rings is relieved and the valve is left freeto move without sticking when the engine is first started.

In the form of valve-head under consideration the desired result is easily secured without material increase incost by forming the bodyportion of metal having a small range of expansibility, such as cast-iron or steel, while the packing-ring support, or, as I have termed itin the present structure, the sectional spider,is formed of metal having a far greater range of expansibility, such as brass. Other metals of course might be employed, if desired, the essential being that the support for the packing-rin gs or wearin g-su rface of the head shall have a greater range of expansibility than the chest in which it works, and if an adjustable head a greater rate of expansion than the body of the head. It is also desirable that the part depended upon to give the greater range of expansion shall be of such shape as to be quickly and evenly affected by changes in temperature as shown, for instance, where the arms 0 are comparatively thin and long.

When a valve of this character is adjusted to fit the chest,it is of course desirable, if not absolutely necessary, that the parts should be in the condition under which they normally operate-11. e., hot-and for this purpose steam may be let into the space between the'heads,

or other means for heating may be resorted to while the adjustment is made. Then when the valve-chest is closed the valve will be found to work perfectly, and will contract sufficiently when cool to prevent sticking or cutting of the wearing-surfaces when the engine is started.

The valve illustrated being formed by two heads, it becomes necessary to provide means for adjusting both while in place in the valvechest, and for this purpose the adj usting-nuts for the sectional spider are located on the outside of each head. In other words, the heads are arranged oppositely on the rod, and both may be adjusted without dismembering the valve.

The advantages of a valve of this character will be at once appreciated by expert steam-engineers, for, besides the ad vantages incident to all piston-valvesby reason of perfect balance, &c., it has advantages incident to its perfect adj ustability and free working qualities, whereby it may be kept in perfect working order without great expense, which place itona par with the best slide-valves heretofore most extensivelyused because of the last-mentioned qualties.

Having thus described my invention, what I claim as new is- 1. In a piston-valve, the combination,with the body formed by the disk having the annular peripheral channel on one side and the central hub projecting on the same-side as the peripheral channel, of the packing-rings in the channel, the sectional spider underlying the rings, the expander surrounding the hub within the valve and co-operating with the sectional spider, and the set-nuts working on the end of the hub to adjust the expander, substantially as described.

2. In a piston-valve, the combination, with the body having the annular peripheral channel and central hub and the packing-rings in said'channel, of the sectional spider having the segmental plates underlying said rings, the central inclined plates, and the radial arms uniting said plates, the conical expander working in the hub and co-operating with the inclined plates, and the set-nuts on the hub for holding the expander in adjusted position, substantially as described.

3. In a piston-valve, the combination, with the body formed by thedisk, having the central hub and slotted flange near its periphery,the face-plate or ring secured to the flange, and the packing surrounding the flange between the disk and face-plate or ring, of the segmental plates underlying the packingrings, the radial arms carrying said plates passing through the slots in the flange, and the conical expander working on the hub for moving the segmental plates outward to tighten the packing, substantially as described.

4. In a piston-valve, the combinatiomwith the disk having the central hub and flange nearthe periphery, having slots or openings therein, the face-plate or ringsecured to said flange, and the packing-rings between said plate and disk, of the sectional spider consisting of the segmental plates underlying the packing-rings, the central inclined plates, and the radial arms passing through the flange and uniting the said plates, the expander working on the hub and having the inclined ribs or projections engaging the inclined plates, and the set-nuts for holding the expander in adjusted position, substantially as described.

5. In a piston-valve for steam-engines, the combination, with the piston-rod, of the two independent heads mounted on said rod and adjustable toward and from eachother, substantially as described.

6. In a piston-valve, the combination, with the valve-rod and the head secured permanently thereon, of the opposite head mounted on said rod and having set-nuts on both sides of the same, whereby it may be adjusted 1ongitudinally of the shaft, substantially as described.

7. In a piston-valve, the combination,with the rod, of the oppositely-arranged heads secured thereon and having the outwardly-projecting hubs and peripheral chambers, the packing-rings, the sectional spiders, the expanders, the set-nuts for adjusting said expanders screwing on the outer ends of the hubs, whereby the heads may be adjusted.

while in the valve-chest and without dismembering the valve, and the nuts on the rod engaging the hub to hold the valve in place irrespective of the adjustment of the expander's, substantially as described.

8. Apiston-valve for steam-engines, having the support for the packing-rings formed of metal having a greater range of expansibility than the valve-chest under the influence of Variations in temperature, substantially as described. 7

9. In a piston-valve for steam-engines, the

combination, with the packing-rings, of the relatively thin radial arms for supporting the same, formed of metal having a greater range of expansibility than the cylinder under the influence of variations in temperature, substantially. as described. j

10. In a piston-valve for steam-engines, the combination, with the body portion, of the packing-rings and the spider supporting said rings, formed of metal havinga greater range of expansibility than the body portion under the influence of variations in temperature, substantially as described.

11. In a piston-valve for steam-engines, the combination, with the iron or steel body portion and the packing-rings, of the supporting-spider for said rings, formed of brass, substantially as described.

12. In a piston-valve for steam-engin es, the combinatiomwith the body portion formed of metal having a small range of expansibility and the packing-rings, of the sectional spider supporting said rings, havingits radial arms formed of metalhaving a greater range of expansibility than said body portion, substantially as described.

13. In a piston-valve for steam-engines, the combination, with the body portion formed of metal having a small range of expansibility and the packing-rings,.of the sectional spider supporting said rings, having relatively thin radial arms formed of metal having a greater range of expansibility than said body'portion, and an expander co-operating with the sectional spider to adjust the same for wear, substantially as described.

MARTIN E. HERSHEY.

Witnesses:

S. W. FLEMING, B. EDWARD TAYL R.

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