US537223A - Island - Google Patents

Description

(No Model.)

H. 0. NICHOLS. GOVERNOR FOR STEAM ENGINES.

Patented Apr. 9, 1895.

mun 4 UNITED STATES PATENT OFFICE.

HENRY C. NICHOLS, OF HOP-KINTON, RHODE ISLAND.

GOVERNOR FOR STEAM-ENGINES.

SPECIFICATION forming part of Letters Patent No. 537,223, dated April 9, 18$ 5.

Application filed November 24, 1890 Serial No. 372,413. (No model.)

T0 on whom it may concern:

Be it known that I, HENRY O. NICHOLS, a citizen of the United States, and a resident of Hopkinton, county of Washington, and State of Rhode Island, have invented certain new and useful Improvements in Governors for Steam-Engines, of which the following is a specification.

My invention relates td thatclass of engines in which the governors are applied directly to the fly-WheeL'orother wheel secured to the main or driving shaft, and regulates the movements of the engine by changing the throw of the eccentric, whereby the cutoff of the steam either earlier or later in the stroke of the piston is effected as the exigencies of the engine may demand.

In steam or air engines in which a cylinder With ordinary ports, piston, valve, 850., IS employed, andalso a crank shaft upon which a governor is carried that controls the speed of the engine by lengthening and shortening the throw of the valve, the steam is cutoff as early in the stroke as is possible, the point of cut-off depending upon the power required. In nearly all engines of this class,

the eccentric proper is carried upon an arm which is pivoted upon some part of a wheel or spider on the main shaft,-in such manner that when the center of the eccentric is in line with the center of the pivot and shaft the throw of the eccentric causes the valve to travel a distance equal to the lap and lead,

and by swinging the eccentric out of this line its throw is increased and the valve made to travel a greater distance and the point of cutoff made later in the stroke. The changing of the eccentric in respect to this line is accomplished by a governor which is also carried upon some part or parts of the wheel or spider and necessarily revolves with it, and

' the centrifugal force of weights revolving with the wheel and normally counterbalanced by a spring or springs is utilized in this form of governor to accomplish this result. As the speed increases, the centrifugal force of the weights increases correspondingly and overbalances the spring. The weights are thereby allowed to move farther from the center of 1'o-- tation, and, in so doing the position of the eccentric is shifted, the throw of the valve shortened, and the engine reduced to its former speed. As the spring and weights balance.

each other under such conditions, they have but little power to resist any force tending to disturb their equilibriu m, and unless the parts with which they are connectedare well balanced, a vibratory motion is imparted to them which is injurious to the engine and the governor. Moreover it is evident that in a governor so constructed, there is a tendency of the eccentric to drop whenever the point upon which it is pivoted is not directly above or below the shaft, or, in the case of a sliding eccentric, whenever its ways are not horizontal.

In slide valves and piston valves as ordinarily constructed, the area exposed to the.

pressure .of the steam at the end connected to the valve stem is less by the cross section of the valve stem than the area at the other, and this inequality in the areas causes an unbalanced condition, the pressure on the greater tending to force the valve stem outward, and when used in a horizontal form of engines, this-force tends to swing the eccentric to one side when connected directly to it and the pivot on which the eccentric is hung is either above or below the shaft, thereby giving an unsteady or vibratory motion to the governor; and, when on a vertical engine, it adds to the weight of the eccentric, when the pivot is not in direct line with the valve stem, causing the vibration to be greater even than in a horizontal engine.

The object of my invention is, to obviate these and other defects, and to produce means whereby greater efficiency in the operation of 'the engine is attained; and, to these ends, my

invention consists, first, in the peculiar combination with the eccentric,-and the valve stem, of a bell crank lever interposed between them, and, second, in various details of construction and arrangements of parts, all as will hereinafter more fully appear.

In the drawing which accompanies and forms part of this specification, and which shows a side elevation, partly in section, of such parts of a horizontal steam engine as will serve to illustrate my invention, A indi cates a valve which may be either a slide or a piston valve, for the admission or cut-off of the steam or air of an engine; B, the valve stem; 0, the governor wheel, and D the shaft upon which the governor wheel-is mounted.

Pivoted to the governor wheel, as at a or elsewhere on said wheel, is an arm I), carrying at its free end, an eccentric, E, having an oval orifice indicated by the dotted line e, through 5 which the main shaft D passes.

Surrounding the eccentric E is a strap F which is embraced by the lower end of the arm II, the latter being pivoted at t' to the end of the bell-crank lever I which, in turn, is

hung upon a pin, i, supportedby a standard J of the engine frames, and at its other end connected to the valve rod B. By thus connecting the valve A with the eccentric E, the weight of the eccentric and its supporting arm, when in the position shown, is transmitted to the valve stem B in the longitudinal direction or the line of the latter, which is not the case when a valve stem is connected to its eccentric through the usual eccentric 2o strap and guide or arm.

Pivoted to the wheel 0, by pivots (1 cl, are levers K K, which are connected and drawn together by a spring, L, and carry weights M, by means of which the levers are thrown outward by centrifugal force when the wheel is rotated. The outer free ends of these levers K K are connected by rods e e with arms ff, projecting outward from a short shaft N having suitable bearings carried by the wheel.

On this shaft, N, is secured a small eccentric or cam, O, that Works in a slot, h, formed in the arm I). A box fitting the said eccentric and sliding in the slot his indicated at 0 in the drawing.

In the construction of the governor per se, I claim no novelty, having chosen this form to illustrate my invention which, as before stated, consists in the method of and means for preventing the action of gravity in the eecentric and arm from causing vibrations in the governor or engine; and while the drawing illustrates some of the parts of ahorizontal engine, it will be obvious that my invention is as well adapted for vertical engines.

In the well known form of valve illustrated, it will be seen that, as shown in the figure, there will be an increase of pressure in the rear end of the valve over what is exerted on the front end a? thereof, owing to'the reduced area of the latter occasioned by the valve stem which projects therefrom. This increase of pressure, in engines where moderately high pressure is used, can be practically so proportioned as to exactly balance the weight of the unbal anced parts of the governor eccentric, and to approximately balance it under ordinary conditions; but with low pressure, while the force would act in the right direction to lift upon the eccentric, it might not be sufficient to balance it. To make up this deficiency, I may increase the area of the rear end of this valve, or at the end opposite to that from which the stem projects, for the greater the pressure of steam used, the greater will be the excess of pressure tending to force the valve stem forward and the force of gravity in the eccentrio and arm is a given quantity.

Having thus described my invention,what I claim as new, and desire to secure by Letters Patent of the United States, is-- 1. In an engine, the combination with a shifting eccentric, a valve and a valve stem therefor, of a strap for encircling the eccentric having a vertically arranged arm, and a bell-crank lever one end of which is connected to the valve stem and the other end to the vertically arranged arm, substantially as described.

2. In an engine, the combination with the valve and a shifting eccentric and governor therefor, of a bell-crank lever having one end supporting the weight of the eccentric and the other end connected to the valve stem, whereby an excess of pressure on the valvein onedirection will counterbalance the weight of said eccentric, substantially as described.

3. The combination with ashifting eccentric governor of an engine, and a reciprocating valve and stem therefor, of a bell-crank lever having one end connected to said rod and having its otherend connected to a support for eccentric, the latter connection being in the vertical line of the axis of the eccentric shaft, substantially as described.

4. The combination with a shifting eccentric governor of an engine, and a reciprocating valve and stem for said engine, of an arm extending substantially vertically upward from the eccentric and; its strap, and a bellcrank lever pivoted to a fixed point and connecting the said arm and valve rod, substantially as described.

In testimony whereof I have hereunto set my hand this 19th1day of November, 1890.

HENRY O. NICHOLS.

Witnesses:

ROBERT W. WATERBURY, WM. H. APPLETON.

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