US373660A

US373660A - Valve-gear

Info

Publication number: US373660A
Authority: US
Publication date: 1887-11-22
Anticipated expiration: 1904-11-22

Description

(No Model.) 2 SheetsSl1eet I.

B. HILL.

VALVE GEAR. No. 373,660. Patented Nov. 22, 1887.

1 I I 2 M E z I K on I l m 31 I w 1 E a Q R *g m I ii pi i m (No Model.) v 2 Sheets-Sheet 2. E. HILL.

VALVE GEAR.

No. 373,660. Patentedflov. 22; 1887.

N. PFIERS. vhowumo m hu. Washlnglan u. (L

ihvrTED STATES PATENT @EEicE.

EBENEZER HILL, OF SOUTH NOBW'ALK, CONNECTICUT.

VALVE-GEAR.

Application filed May 18, 1857. Serial No. 238.5?0. (No model.)

T 0 (ill? whom, it may concern.-

Be it'knou'n that I, EBENEZER HILL, of South Norwalk, in the county of Fail-field and State of Connecticut have invented a new Im-' provement in Valve'Gears; and I do hereby declare the following, when taken in connection with accompanying drawings and the let ters of reference marked thereon, to be a full, clear, and exact description of the same, and which said drawings constitute part of this specification, and represent, in-

Figure 1, aside view ofthe cylinder portion of an engine, illustrating the valve-gear as in one extreme position. Fig. 2 illustrates the valve-gear as thrown to the other extreme position. Figs. 3 and 4 are modifications.

This invention relates to an improvement in valve-gears for steam-engines or air-compressors, which, so far as the valve-gear is concerned, are the same thin I therefore term the invention valve-gear forsteam-engines, and the invention relates particularly to that class in which the valves slide or oscillate, the valve-gear being the same in either case.

The object of the invention is to prevent the valve cutting when it becomes dry or is f 2 valve at one end of the cylinder, and E the shaft of the valve at the opposite end of the but improperly lubricated.

Heretofore valves in air-compressors have been operated both in their opening and closing movement by positivelyact-ing cams. In the larger class of steam-engines valves have been operated by cams adapted to open the valves, but the valves return by their own weight-such, for instance, as comniom steamboatengines. In other engines valves have been positively opened and returned by springs after the cam shall have escaped from the valve-connection. In this class of valves returned by a spring, as in the Corliss engine, the valves are tripped and return with great force, so great that dash-pots or cushions are necessarily introduced, against which the valve mechanism will complcteits return movement. Under this class, as well as under the class which are returned by weight, while the return movement is not positive, the valve under the action of the weight or spring attains so great momentum that it amounts to a positive return, and the cutting under insufficient lubrication is equally as great as when returned by the positive movement. I avoid this cutting action by imparting to the valve in one direction a positive movement, but in the return compel that return movement to be slow and the power so weak that the cutting action under insufficient lubrication is avoided, the positive movement of the valve being the opening movement, and the return movement being retarded under a weak force.

To this end my invention consists in an elliptical cam, positively operated from the cocentric, combined with a corresponding elliptical toe in connection with the valve, theelliptical surface of the cam and the toe working together, and a spring the tendency of which is to hold the working-faces of the toe and cam in cont-act, and so that on the return of the valve its toe follows the cam only under the action of the said spring, as more fully hereinafter described.

In illustrating the invention, A represents the cylinder; B, the piston cross-head; C, the connecting-rod which extends therefrom to the drivingcrank-a common construction, details of which it is unnecessary to illustrate.

I represent the valve as of an oscillating character, D representing the shaft of the cylinder. F represents the cam, adapted to operate the valve sliaft D, and is hung upon an axis, a.

0 represents the cam for operating the valveshaft E. It is hung upon an axis, 1), the axes of the shafts D E and earns F G being parallel with each other.

To the cams F C an oscillating movement is imparted through the eccentric rod H, which isactuated by the eccentric in the usual man-*- ner, the eccentric not being shown. The eccentric-rod H is connected to an arm, d, ex tending from the hub of the cam F, and from that arm a connecting-rod, I, extends to an arm, 0, on the canrG, so that under the movement of the eccentric the two cams F G will be turned from one extreme, as seen in Fig. 1, to the other extreme, as seen in Fig. 2. On the shaft D of one valve is a toe, L, having an elliptical face corresponding to the elliptical face of the cam F, and so as to work thereon, the cam and toe arranged to oscillate in the same plane, and the shaft E of I the other valve is provided with asimilar toe,

M, having an elliptical face corresponding to the elliptical face of the cam G, and so as to Work thereon. The toe L and cam F are connected by a spring, 0, the spring being hung to the toe L on one side its axis and to the cam F upon the opposite side of its axis, as seen in Fig. 1, and so that the spring tends to hold the faces of the two in contact, but yield under the rotative action of the cam. The toe M and can] G are in like manner connected by a spring, P, which in like manner holds the two faces of the cam and toe in contact.

In Fig. 1 the position of the cam F and toe L is the position when the valve is open. The spring is therefore in its contracted position as holding the toe L against the face of the cam F, and so that as the cam F retreats under the action of the eccentric the toe L will follow it to the position seen in Fig. 1, which is the closed position of the valve. This closing movement extends the springs. Because of the connection of the spring the toe L necessarily follows the cam F and rocks upon its face, so that its return movement is steady and easy, corresponding to the elliptical faces of the toe and cam.

At the other end of the cylinder the toe and cam are represented with the valve in the closed position, so that under the action of the eccentric before referred to the cam G is turned toward the toe M, and working upon its face turns the toe M to the position seen in Fig. 2, this movement being positive, the spring contracting under such movement. On the return of the eccentric the cams will act upon their toes accordingly and bring them again with their respective valves to the position indicated in Fig. 1.

The shape of the working-faces of the cams will be adapted to the required variations of the motion of the valve.

In the arrangement of spring which I have illustrated connecting the cam and toe at opposite points of their respective axes, the spring is extended from both ends, and this arrangement I prefer, believing it to produce the best result; but the spring may be other Wise arrangedsay as seen in Fig. 3, where the spring is hung by one end to the cam and the other to a stationary point-it only being essential to the invention that there shall be .a spring adapted to hold the faces of the toe and cam together, so that the return of the toe is produced by a yielding action of the spring, but governed by the cam. The rest of the valve in the closed position is produced by the hub of the cam, which is concentric with its axis, so that it works against the face of the toe without action thereon to the required extent.

In case the slide of the valve be in a direct line, instead of oscillating, as I have described, it will be understood that the toe will be prothe valve is not positive and is made under the action of a spring, it avoids the sudden and accelerated movement of the valve which unavoidably follows the employment of a weight or spring under the arrangement to which I have before referred, and this slow or retarded and regular return of the valve will avoid the cutting action which necessarily follows the quick accelerated or positive return.

In some cases it may be desirable to provide the cams and toes with gear-like teeth, to insure their constant proper relation to each other-say as indicated in Fig. 3--and these teeth should be arranged-to engage when the valve is in the open position.

The elliptical shape of the faces of the cam and toeI find to produce the most satisfactory movement of the valve both in opening and closing; but the faces may be ofother than elliptical shape, as seen in Fig. 4, where I represent the toe as presenting a straight face to the cam.

I claim- 1. In a valvegear for steam-engines and similar purposes, the combination of a cam adapted to receive an oscillating movement from the eccentric, a toe hung upon an axis and in connection with the valve, whereby said toe is adapted to oscillate in the same plane as the said cam, the face of said cam adapted to work against the face of the said toe, with a spring in connection with said toe,

and adapted to hold the face of the toe against the face of the cam in the return or closing movement, substantially as described.

2. In a valve-gear, the combination of an oscillating cam adapted to receive its oscillation from the eccentric, a toe in connection with the valve and adapted to oscillate in the plane of oscillation of said cam, with a spring connected to both said toe and cam, substantially as described, and whereby the faces of the said cam and toe are held in contact during the return or closing movement of said toe.

3. In a valve-gear, the combination of an oscillating cam having an elliptical face in connection with the eccentric, whereby oscillating movement is imparted to said cam, a toe in connection with the valve having an elliptical face corresponding to the face of said cam, the said cam and toe arranged to oscillate in the same plane, with a spring in connection with said toe and adapted toyieldingly hold the face of the toe upon the face of the cam in the return or closing, movement, substantially as described.

EBENEZER HILL.

Witnesses:

J OHN A. SLATER, J A0013 M. LAYTON.