US325964A - Valve-gear - Google Patents

Description

2'Sheets -Sheet 2.

(No Model.)

M.N.PAGKARD.

VALVE GEAR. "No. 325,964. Patented Sept; 8, 1885 witmqooao l r I awum woz 7 Q3313 akto mwq wa WWW J? UNITED STATES PATENT OFFICE.

'MonRniL N. PACKARD, or BALTIMORE, MARYLAND.

VALVE-GEAR.

SPECIFICATION forming part of Letters Patent No. 325,964, dated September 8, 1885. Application filed July 20, 1885. (No model.)

To all whom it may concern:

Be it known that I,.MORRILL N. PACKARD, a citizen of the United States, residing at Baltimore, State of Maryland, have invented certain new and useful Improvements in Valve-Gear for Steam-Engines; and Ido hereby declare the following to be a full, clear, and exact description oftheinvention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to improvements in valve-gear for steam-engines; and it has for its object to provide a gear simple in construction, durable in use, and one which can be easily and cheaply manufactured.

The nature of the invention consists in the combination, with a valve-stem, ofa vibrating lever whose upper portion forms a link pivoted to the stem, and a fulcrum-block fitted in said link and adapted to be moved by suitable actuating mechanism to positions above or below the pivotal point of the link for the purpose of changing the order of the lever and consequently changing the direction of movement of the valve-stem with relation to that of the arm of the lever. I

Figure 1 of the drawings is a side view of my invention, showing the preferred construction. Fig. 2 is a perspective view of the same. Fig. 3 is a perspective View illustrating a modification. Fig. 4 is a side viewof my improved valve-gear attached to'an engine.

Referring to the drawings,'A represents the valve-stem, having bearing in brackets to, at-

tached to any convenient part of the frame work of the engine.

Pivoted to the valve-stem, between the bracket-bearings a, is a lever for actuating it, this lever comprising a link, B, and an arm, B. In the back of the link B is formed a guide-groove, b,'for the accommodation of a fulcrum-block, which will be presently described. For the purpose of making the link as light as possible, its face is cut out, as at b b, leaving a bridge-piece, b, by which to con nect the link with the valve-stem.

Sliding in groove 12 in link B is a fulcrumblock, D, loosely attached to any suitable actuating mechanism. A preferable mechanism v for sliding the fulcrum-block, and also for steadying it in its movements in be described as follows:

the link, may

0 represents a guide, attached to any suitable part of the machine,in which guide is fitted a sliding guide-block, F. This guide-block is rigidly fixed on one end of a shaft, G, and on the other end of said shaft is journaled the fulcrum-block. Shaft G, and consequently blocks D and F, is raised and lowered by means of a lever, E, attached thereto, which .lever is pivoted, as at e, to the frame-work of the engine, and is connected at its inner end with any desired operating mechanism. The guideway c in guide 0 is slightly curved, as shown, in order to conform to the arc of a circle described by the'guide-block in moving from one position to another. The corresponding are described by the fulcrum-block is compensated for by a slight movement of the valvestem. Ican, however, dispense entirely with guide 0, guide-block F, and shaft G by bending the end of lever E at a right angle and journaling the fulcrum-block thereon, as shown in Fig. 3.

In Fig. 4 I have shown my valve-gear applied to an engine, in order to clearly illustrate its operation, the inner end of lever E being attached to a link, e, pivoted to an arm, 6'', on a rock-shaft, I. To this shaft is attached a lever, J, provided at its upper end with a spring-pawl for engagement with teeth in a toothed segment, K, whereby lever J and'the mechanism operated by it are held in any desired position. It is to be understood, of course, that the hereindescribed valve-gear is to be applied to each side of the engine.

' Lever B B may derive its vibratory motion from the cross-head'of the engine, as seen in Fig. 4; but I do not wish to confine myself to the construction therein shown, as it will be at once apparent to the machinist that other means may be employed for actuating the lever-as, for instance, an eccentric on the driving-shaft.

As represented in Fig. 4, the lower end of arm .13 (which is preferably flattened for the purpose) rests between friction-rolls h in the cross-head H, and as the piston-rod moves forward and backward it imparts movement to lever B B, and through the lever' to the valve-stem.

It will be observed that the movement of the valve-stem relatively to that of the piston- 1 rod is governed by the position of the fulcrum- ICO block in link B, for when it is above the pi"- otal point I), as seen in Fig. 4, lever B B is of the second order, and therefore the valvestem is moved in the same direction as the piston-rod. This, however, is changed when the fulcrum-block is drawn down to a position below the pivotal point, for then the lever becomes one of the first order, and consequently the valve-stem is moved in a direction contrary to that of the piston-rod.

Lever E must be so regulated as not to permit the fulcrum-block to reach the bottom of the guide-groove in link 13 when the latter is in a vertical position, as seen in Fig. 1. This arrangement is rendered necessary by the fact that when lever B B is at the extreme limit of its throw in either direction the distance from its pivotal point to the center ofthe fulcrum-block is greater than when it occupies a vertical position, and consequently allowance must be made for play of the link on the block to compensate for this difference.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is

1. In a valve gear for steam-engines, the

. combination, with a valve-stem, ofa vibrating lever whose upper portion forms a link pivoted to the stem, and a fulcrum block fitted in said link and adapted to be moved by suitable actuating mechanism to positions above or below the pivotal point of the link, substantially as described, and for the purpose set forth.

2. The combination, with a crosshead and a valve-stem of a steam-engine, of a lever whose upper portion forms a link pivoted to the stem, and a fulcrum-block fitted in said link and adapted to be moved by suitable actuating mechanism to positions above or below'the pivotal point of the link, substantially as described, and for the purpose set forth.

3. The combination, with a cross-head and a valve-stem of a steam-engine, of a lever whose upper portion forms a link pivoted to the stem, a fulcrum-block fitted in said link, a guide secured to any suitable part of the engine, a guide-block fitted to slide therein,

a shaft connecting the fulcrunrblock and the guide-block, and a lever for actuating the shaft, substantially as described.

4. The combination, with a valve-stein of a steam engine, of a vibrating lever whose upper portion forms a link pivoted to the stem, a fulcrum-block fitted in said link, and an actuating-lever on the end of which the ful crum-block is journaled, in the manner and for the purpose set forth.

In testimony whereof I affiX my signature in presence of two witnesses.

MORRILL N. PACK ARD.

\Vitncsses:

JOHN T. ARMS, GEO. I. HILL.

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