US337293A - Valve-motion - Google Patents

Description

(No Model.)

J. S. ASH.

VALVE MOTION.

4 Patented Mar. 2, 1,886..

Ta G01/'Eril o7:

I .Ta Steam mZvQ,

.ATTO R N EY.

N PETERS. Phmqumugmpher. wammgmn. u. C.

NTTE STATES PATENT EETCE.

JOHN S. ASH, OF BUCKINGHAM, PENNSYLVANIA.

VALVE-MOTION.

SPECIFICATION forming part of Letters Patent No. 337.293, dated March 2. 1886. Application filed August 1, 1855.v Serial No. 173,237. (No model.)

To @ZZ whom t may concern.-

Beit known that I, JOHN S. ASH, a citizen of the United States, residing at Buckingham, in the county of Bucks, State of Pennsylvania, have invented a new and useful Improvement inValve-Motions and Out-Offs, whichimprovement is fully set forth in the following speciiication and accompanying drawings, in which- Figure 1 represents a side elevation of a valve-motion and cut-off embodying my inven tion. Fig. 2 represents a front view thereof.

' Similar letters of reference indicate corresponding parts in the two figures.

Myinvention relates to that class of engines in which separate valves are employed for the admission and release of steam and the objects of my improvements are, first, to secure an automatic cutoff for the steam-valve having a Wide range; second, to maintain a nearlyconstant lead throughout the entire range of cutoff; third, to secure a rapid cut-off, (preventing wiredrawing;) fourth, to give decision to all the events 0f the travel for both the steam and the exhaust valves; fifth, to secure small travel of the valves, especially during the time they remain closed.

Its objects are further to dispense with the releasegear common on this class of engines, and to secure ,certain other advantages of construction and detail, to be hereinafter described.

Vith these ends in View my invention essentially consists in a rocker-arm for operating the steam-valve, deriving its movement through a connecting-bar from a crank on the main or crank shaft of the engine, and communicating this motion th rough suitable connections to the valve, `regard being had to a change of cut-off, which is effected by moving the rocker-arm supportk and to constant lead. The latter is secured by additional mechanism, to be described The rocker-arm referred to is placed very near the crank giving it motion, and the connecting-bar made very short, thereby increasing the irregularity of the reciprocating motion derived from eccentric and crank connections. A similar rocker-arm imparts motion 'to the exhaust-valve.

For sim plicityIshall confine my description to the case of a single-acting engine, as the parts may be readily duplicated, as desired.

Referring to the' drawings, A represents the bed-plate of an engine, Bthe pillow-block, and C the main shaft thereof. A bracket or support, D, is firmly bolted to the bed-plate A of the engine, and carries the pin F, the axis of which coincides with the axis of the main or crank shaft O of the engine.

Oscillating on the pin F is the lever G, to the upper end of which is pivoted the rod G', running to the steam-valve, and to the lower end, at G2, is pivoted the bar H, and this to the rockerarm J, keyed on the rockerrshaft K.

On the inner end of the rocker-shaft K is the rocker-arm M', to the outerend of which is pivoted the connecting-bar P, which turns on the pin Q, said pin Q passing through a crank or connecting-piece, R, which latter is also firmly attached to the main crank of the en gine, leaving the connecting-rod of the engine free to operate in the ordinary way.

The crank Ris designed to lessen the throw of the valve-movement, and its length may be varied, as required. When its length is reduced to zero, the pin Q and the main crankpin of the engine become identical.

Also loosely placed on the pin F is the armed disk M, the upper end of the arm of which is attached to the rod N, running to the governor. This disk'carries in the boss L the rocker-shaft K, above mentioned. Turningpn' the pin Q is also a connecting-bar, S, pivoted at the end opposite to the piu Q-to the rockerarm T. This rocker-arm T is secured to the shaft U, to which is also tirmly securedanother arm, W, to which is pivoted the rod'X,'run ning to the exhaust-valve. A

In an'engine having a crank-shaft bearingon each side of the crank the crank shaft may serve the purpose of the pin F, motion being derived from a small crank on its outer end.

In certain constructions the rocker-arm M vroo Having described the construction and relai tive arrangement of the several parts of my its motion.

valve-movement, I will nov7 describe its operation. The crank R, being rigidly attached to the main crank of the engine, gives to the pin Q, and consequently to the end of the connecting-bar P attached thereto,a rotary motion. The other end of the bar P, being attached to the rocker-arm M', imparts an oscillatory motion to said rocker-arm, and consequently to the shaft K and arm J. This being connected by the bar H with the lever G imparts a similar motion to the latter, which is communicated by the rod G' to the steam-valve, y y

The bearing L for the shaft K, which is in a boss on the armed disk M, being free to rotate about the pin F, is under the control of the governor, and thus controls the point of cutoff. The connecting-bar S, having one end attached to the pin Q, has imparted to this end a rotary motion, and the other end, being confined by its connection to the are described by the rocker-arm T, imparts an oscillatory movement to the latter, and hence to the rocker-shaft U. The arm W, being secured to the same shaft U, also receives an oscillatory movement, and, as the rod Xis attached to the arm W and runs to the exhaust-valve, gives a reciprocating motion to the exhaustvalve. It is clear that the steam and exhaust valves Work quite independently and have no necessary,connection with one another. VVhe'n the angular position, as effected by the governor on the disk-arm M, changes with reference to the crank,'since the arc described by the rocker -arm M' is the same whatever its position, it is evident that to maintainv a constant lead the valve-opening should take place at times corresponding to different points in said arc, such points agreeing with the position occupied by said rocker-arm when the crank occupies the position representing the desired lead, and also agreeing with the different points of cut-off.

Reference to the drawings, Fig. 1, will show that when the crank is near the end nearest thecylinder, the pin Q and the end of the rocker-arm M' will move through nearly equal distances, the parts being so arranged and proportioned that at this time the rocker-arm M' and the connecting-bar P are nearly perpendicularto each other. This enables me to keep the lead constant by transferring the motion of the rocker-arm M through the connections above named to the lever G, and allowing the lead-opening to take place when the end of said lever is traveling in a direction nearly parallel to the motion of the valve, and consequently imparting a movement to the latter which is nearly the same, or having a direct proportion to the movement of the lever G, as also of the parts from which it derives In other words, the movement imparted by the governor to ther armed disk M about the pin F, measured at the distance of the pin Q from the center of the crank-shaft, and of the bearing supported by said disk about the shaft K, measured at the end of the rocker-arm-M, are equal, and they are also equal to the movement of the disk with reference to the lever G, (also measured at the distance Q from the center,) said lever being held by the bar H. q

The following proportions must be observed: Length of rocker-arm M' :half the throw of pin Q :length of arm J :length of arm G. The effect of this is to allow any motion iinparted by the governor to take place Without affecting the lead, and at the same time allow a very quick valve-opening. I

Ido not conne myself to placing the pin F in line with the crank-shaft of the engine, but it may be placed at any convenient point, movement being communicatedto the parts by suitable gearing; nor do I wish to confine myself to the exact construction above given, as it is evident that this may to some extent be altered Without departing from the spirit and scope of my invention.

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

1. The support D, carrying the pin F, 'the axis of which coincides with the main shaft C, in combination with the lever G, connected to the rod G', the lever G, connected bythe rod H to the rocker-arm J, the rocker-arm M', the

connecting-bar P, and crank R, turning on the pin Q, said crank R being rmly attached to the main crank of the engine, armed disk M, and rod N, connecting-bar S, turning on the pin Q, and rocker-arm T, secured to the shaft U, having 'adjustable `bearing V', both bar S and arm T being connected by a pin-arm, W, having the rod X pivoted thereto, and disk V, all of said parts being arranged, combined, and operated substantially as described. V

IOC'

2. rlhe pin Q, connected bythe crank R n with the main crank of the engine, in combination with'the bar P, rocker-arm M', rockershaft K, rocker-arm J, bar H, and lever G, communicating motion to the steam-valve, as specified.v

3. The crank R and pin Q, connected with the crank, in combination with the bar `S, rocker-arm T, rocker-shaft U, and rocker-arm IIO W, communicating motion to the eXhaustvalve, the rocker-shaft being placed closeto the center, as and for the purpose specied.

4. The support D, carrying the `pin F, in combination with the slotted disk V, rocker'- shaft U, having adj ustable bearing V', and setby a nearly stationary point, which extends over a considerable portion of the crankrev olution, said travel being communicated to the steam-valve by suitable intermediate parts.

6. The disk M, having its position about l the center F determined by the action of the governor, in combination with the lever G, moving about the same center, the rocker-arm J and bar H, and rocker-shaft K, supported on said disk, and having motion communicated ro thereto by suitable mechanism from the crankshaft of the engine, and imparting through other suitable connections motion to the steamvalve, as and for the purpose specified.

JOHN S. ASH. Witnesses: S. EDWARD PAscHALL,

CHARLES A. CUFFEL.

Images