Year: 1889

page_text: Date of Application, 8th Jan., 1889.
Specification Accepted, 23rd Feb., 1889
I, DAVID PLUMB DAVIS, of Allendale, in the County of Bergen and State of New
Jersey, one of the United States of America, Engineer, do hereby declare the naturo
of this invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
My invention relates to Governors that are adapted to act upon the eccentric of the
cut-off mechanism of a steam engine, so that the position of the center of the eccentric
with relation to the axis of the shaft will be changed, and a variation of stroke
produced to govern the supply of steam by the period of cut-off and, thereby com-
pensate for the varying loads put upon the engine. Heretofore, various devices have
been employed to overcome the difficulty arising in holding the eccentric rigidly
against displacement due to the frictional resistance of the slide valve or other cut-off
mechanism.
6
To accomplish this end is the object of my invention and the object is also to
promote the sensitiveness of the speed regulation, by the employment of a minimum
sized centrifugal governing weight which the present invention admits of.
My improved mechanism consists of a liquid confined piston adapted to hold the
eccentric at such various positions as it may be caused to assume, and of valves that
lock the flowing ports through which the liquid is admitted or withdrawn from either
side of said piston; the said valves being operated by means of the centrifugal governing
weight.
Referring to the accompanying drawings forming a part of this specification, and in
which similar letters of reference indicate corresponding parts throughout the several
views:
Figure 1, is a front elevation of a fly-wheel or driving pulley bearing a movable
eccentric, an eccentric shifting weight and spring, and the liquid locking device
connected therewith.
Figure 2, is a central transverse section of Figure 1, and
Figure 3, a sectional detail view on the line, x, x, Figure 1.
Figure 4, is a view corresponding to Figure 1, omitting the eccentric shifting weight
and spring.
Figure 5, is a front elevation illustrating the invention applied to a modified
construction of the movable eccentric.
Figure 6, is a transverse section on the line, y, y, Figure 5.

page_text: Figure 7, is an enlarged detail view taken in cross-section on the line, y', y'
Figure 8, and
Figure 8, is an enlarged detail view taken in section on the line, z, c, Figure 7.
Referring to Figures 1, 2 and 3, C, is the eccentric operating the slide valve or
other cut-off mechanism of the steam cylinder; D, guideways upon which the eccentric
is made movable transversely, but rotatively carried with the driving pulley, A, and
shaft, B.
The eccentric block, C, is slotted as shown at, F, to permit its movement over the
shaft upon the guideways D, the latter being attached to the hub of the wheel. The
guideways are preferably of beveled form as shown, the wear of the same being taken
up by a gib, a, having tightening bolts, b.
G, is a centrifugal weight that actuates the eccentric block upon its guideways,
and, H, an opposing contractile spring counteracting the centrifugal force of the said
weight. Both the weight and the spring are made adjustable as to efficiency; the
former, by its sectional construction, c, d, e, whereby it may be built up or decreased
as circumstances require; and the latier by its screw shackle connections to the eccentric
block, and to the rim of the wheel, respectively, by right and left screw-threads
provided with jamb nuts, k.
I, is a piston rod extending from the weight, G, bearing a piston, J, (Figure 8,)
within the cylinder, K, which latter is swivelled to the rim of the wheel at a point, f,
diametrically opposite the suspending point of the spring, H.
L, is the centrifugal governing weight, adjustable upon the lever, g, fulcrumed as
shown, carrying with it a cylinder valve operating shaft, h.
Counteracting the weight, L, is the contractile spring, M, connected by adjustable
screw shackle connections similar to those of the spring, H, between the armi, of the
lever, g, and the wheel rim.
In Figure 4, the piston rod, I, is shown connected with the eccentric block, C,
operating in guideways, D, similarly to Figure 1. The centrifugal weight, G, is in
this instance omitted, as also its counteracting spring, and the frictional resistance
of the cut-off mechanism upon the eccentric, is depended on to move the eccentric
from one position to another when the piston in cylinder, K, is released.
In Figure 5, the piston rod, I, is swivelled to the eccentric, (; and the said eccentric
is moved upon a fulcrum at, O, of its arm, N, in lieu of operating in guideways as
in the former instances. The slot, F, is curved to correspond with the center of
movement, and a small curved slot, P, and guiding stud therein is also provided
to retain the eccentric in its plane of movement and prevent its being displaced
laterally.
The form illustrated in Figure 5. may be used in connection with the invention
with or without the centrifugal weight, G, and spring, H.
Referring to Figures 7 and 8, the opposite chambers of the cylinder, K, are filled
with liquid, preferably such as oil and glycerine, or other non-freezing compound, and
they communicate by the run-around ports, j, through chamber, when the inter-
cepting check valves, 1, 1, are open. N, is à cam within the chamber, fixed to the
shaft, h, which cam engages with the webbed stems of the check valves, 1, 1, so as to
alternately lift the one or the other from its seat when the weight, L, is retracted
toward or thrown from the center of the wheel, as the case may be. The reseating of
the valves when released by the can is assisted by the valve springs n.
The shaft, h,
of the cam is packed tight through the gland, s, being left free to rotate.
m, are cramping screw plugs used to adjust the capacity of the ports and regulate
the amount of retardation offered to the flow of the liquid and to the movement of the
eccentric.
In Figures 1 to 6, inclusive, the eccentric is shown in a position to give the minimum
stroke and to cut off the admission of steam to the engine cylinder at an early period
of the stroke of the steam piston. in operation, as the engine assumes its normal
speed, the weight, L, arrives at its mid-position shown in the Figures wherein the
cam, N, is disengaged from both valves, 1, 1, the said valves remaining seated so as
to lock the piston, Jinactively between the confined liquid. An increased load upon

page_text: the engine will cause the retraction of the weight, L, in the direction of the arrow, o,
causing the cam, N¹, to bear upon the check valve, l. The contractile action of the
spring, H, then moves the piston, J, and weight, G, toward the axis of the shaft,
carrying the center, a², of the eccentric in the direction of the arrow to give an
extended stroke. A decreased load is followed by the opposite action of the weight, L,
in the direction of the arrow, p, lifting the check valve, 11, causing an opposite
automatic movement of the several parts until a normal speed is resumed.
It is obvious that a similar operation will take place in the absence of the weight
and spring, G, H, due to the frictional resistance on the eccentric as aforesaid; the
back and forward pressure of the eccentric strap incident to each revolution being
yielded to one way or the other at the successive turns, according as the check valve, 7,
or, A, may be raised.
The slot, F, being extended both ways across the eccentric disk, enables the direction
of rotation in which the engine is driven to be reversed by disconnecting the piston, I,
and reversing the position of the eccentric.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1st. In a governor for engines, the combination of an eccentric operating the cut-off
mechanism capable of variable adjustment of its center to or from the axis of the shaft,
with a liquid confined locking piston connected with said eccentric and adapted to hold
the same against displacement during rotation, or to release the eccentric by the
release of the liquid confining said piston.
2nd. In a governor for engines, the combination of an eccentric operating the cut-off
mechanism capable of variable adjustment of its center to or from the axis of the shaft,
with a liquid confined locking piston connected with said eccentric, check valves
normally opposing the escape of the liquid confined upon either side of said piston, and
an automatic check valve tripping mechanism, consisting substantially of a centrifugally
operated weighted lever, a retracting spring, and a tripping cam or toe operated
by said weighted lever and spring to release the confined liquid in the manner set
forth.
3rd. The combination with an eccentric transversely movable in parallel guideways
for the adjustment of its center at variable distances from the axis of the shaft,
of the herein described liquid confined locking piston, liquid releasing valves,
centrifugal valve operating weight, and counteracting spring, adapted as and for the
purposes herein set forth.
4th. The combination with an eccentric swivelled upon a fulcrum aside from its
center, to move transversely for the adjustment of its center at variable distances from
the axis of the shaft, of the herein described liquid confined locking piston, liquid
releasing valves, centrifugal valve operating weight, and counteracting spring, adapted
as and for the purposes herein set forth.
5th. The combination with an eccentric transversely removable for the adjustment
of its center at variable distances from the axis of the shaft, a centrifugal eccentric
moving weight, as, G, and a retracting spring, as, H, of the herein described liquid
confined locking piston, liquid releasing valves, centrifugal operating weight, and
counteracting spring, all adapted as and for the purposes set forth.
T
1000
DAVID PLUMB DAVIS.
By Jensen & Son,
77, Chancery Lane, London, W.O.,
Patent Agents.