Improvements in Auxiliary Valve Gear for Motive Engines.
Year: 1898

page_text: Date of Application, 11th Oct., 1898-Accepted, 23rd Dec., 1898
COMPLETE SPECIFICATION.
Improvements in Auxiliary Valve Gear for Motive Engines.
We, WILLIAM HILLMAN CUTLER, of Freeport, in the County of Queens, and State
of New York, and STEPHEN VERNER GODDEN, of Boston, in the County of Suffolk,
and State of Massachusetts, United States of America, Engineers, do hereby
declare the nature 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:
Our present invention relates to auxiliary valve gear for motive engines, of which
the following is a full, clear and exact description, such as will enable others skilled
in the art to which it appertains to make and use the same, reference being had to
the accompanying drawings forming a part of this specification, in which
Fig. 1, is a side view, partially in section, showing a portion of a typical engine.
of the reciprocating species, including the eccentric gear and the link motion
reversing gear, the rocking arm and the reciprocating valve, with our improved
auxiliary or intermediate gear interposed between sections of the valve rod.
Fig. 2 is a longitudinal section of our improvement, showing the stationary shell,
the tubular rotary can within the same, portions of the valve rod and rocker arm
rod, and mode of connecting the same with the tubular rotary cam.
Fig. 3 is a transverse sectional view of the same, taken on line x-x, with bracket
for attachment to stationary frame-work.
Fig. 4 is a view of the tubular rotary cam, showing outer cam groove, and broken
away to show also a portion of the inner cam groove.
Fig. 5 is a transverse section of the same, taken on line y-y.
Fig. 6 is a perspective view of the tubular rotary cam, showing exterior cam
groove, and broken away to show mode of connection of valve rod with interior
cam groove.
Fig. 7 is a detail view showing the end of valve rod and its mode of connection
with the interior cam groove.
Fig. 8 is a detail view showing the end of the rocker arm rod and its mode of
connection with the interior of the tubular rotary cam.
Like letters of reference indicate like parts in the several figures.
Our invention relates to improvements in the valve gear of motive engines operated
by elastic fluids, as steam, gas or air, particularly the class of reciprocating engines
employing slide, valves operated by eccentrics on the main rotating shaft in
connection with the well known "link motion" for reversing gear. It is well known
that this device in its original form is wasteful of steam at some points of the stroke,
and sparing of steam at other points, both on the supply and exhaust sides of the
piston, in respect to obtaining the fullest and best effects, owing to the uniformly
accelerated and retarded movements of the slide valve under the operation of the
eccentrics, which give it regular reciprocating movements similar to those of a
pendulum. It is a desideratum to correct this defect by imparting to the valve such
an irregular to-and-fro movement as the best conditions require for economy of
steam combined with fullest expenditure thereof for maximum efficiency, and many
devices have been contrived to accomplish this result. This problem we have

page_text: practically solved by our present invention, which consists in placing at some point
in the rod or other means which ordinarily connects the reciprocating valve with
the rocker arm actuating the same, and which derives its oscillating motion from
the eccentrics on the main shaft, an auxiliary gear of peculiar improved construction
which shall so modify the equable and pendulous movements of said rocker arm
and rod when imparted to the valve as to introduce the irregularities of move-
ment above explained as necessary for the best results. This auxiliary device
is, in its most essential feature, a tubular rotary cam, illustrated in the
accompanying drawings, which we now proceed to describe.
In Fig. showing the relation of our improvement to the other connected
parts of the engine, F is the valve, the rocker arm, B the valve rod section,
and C the rocker arm rod section.
ཐ་
A, (Figs. 1 and 2), is a stationary tubular shell detachably or otherwise firmly
fixed to some immovable part of the frame work of the engine, in the path of the
ordinary rod connecting the rocker arın E with the reciprocating valve governing
the admission of steam to and from the cylinder. Said rod is divided into sections B
and C, the former leading to the valve, and the latter connected to the rocker arm
in the usual manner. Within the said shell A is fitted a tubular rotary cam D, so
as to move freely therein, said cam being connected to rocker arm rod C, by means
of the button head c on the rod, fitting and freely rotating in the annular groove c¹,
formed on the interior surface of the said tube near the end thereof. On the
extremity of the valve rod section B is formed a head b, having at diametral
extremities thereof pins or projections b1, b¹, which engage a cam groove of irregular
contour formed in the interior surface of the tube D, as shown in Fig. 6. The
said tube D is thus so far free to rotate axially within the shell A, governed only
by the relative positions of cam groove e, and pins 61 61. On the exterior of the
tube D is formed a cam groove d, also of irregular contour into which when in
operative position projects a pin a, firmly held in the perforation f in the shell A
by screw thread or other suitable connections. This pin a, by means of the said
cain groove, governs the combined longitudinal and rotary motion of the
tube D in accordance with the law of its construction, as the said tube is thrust
forwards and backwards by the impulse given to the rocker arm rod with
These movements in
which it is rotarily connected.
turn govern the
movements of the interior cam groove e from which the valve-rod B
receives its forward and backward movement, converting the motion thereof
from the equable pendulous movements of rocker arm rod C into irregular
retarded and accelerated longitudinal movements compounded of the combined
longitudinal and rotary movements given to the cam by the form of the outer cam
groove d, and the irregular compound movements thus generated reconverted into
longitudinal to and fro movements by the action of interior cam groove e on the
head of valve-rod B, which compound movements, carefully predetermined by
mechanical calculation in laying out the forms of the cam grooves and e, are
transmitted to the valve so as to generate the movements required for the desired
mode of admission and emission of steam or other clastic fluid to and from the
cylinder. No specific rules for the laying out of these cam grooves are here given,
as the same vary with circumstances and required conditions, and the art is one of
mechanical mathematics within the province of the artisan skilled in the art.
"
Since the pins or projections 616, on the head b are preferably made in duplicate
as shown, the cam groove e is also made with duplicate corresponding branches to
accommodate the said projections engaging therewith. In order to introduce the
head with its projections 61 61 into engagement, the cam groove e is made with
outlets at the margin of the cam tube suitably located so as not to interfere with
the function thereof. Cam groove d may also be duplicated.
In case the whole effect should be desired to be relegated to the outer cam groove,
as may be the case when only retarding movements are contemplated, the head b of
valve rod B may be formed as a circular button rotating in an annular groove
similar to groove c¹ at the other end of tube D. These annular grooves in the cam

page_text: tube are made with screw threaded junctures, both to facilitate the introduction of
the button heads and to facilitate construction. These junctures are also arranged
to compensate for wear.
In case it is desired to use the engine with a rigid valve rod without auxiliary
gear to introduce irregular movements, that end may be accomplished by locking
the cam tube D against rotary movements, giving it only longitudinal linear
reciprocating motion corresponding to that, of the rocker arm rod, of which it forms
a connecting link with the valve rod. This may be done in any suitable manner
known to mechanics. We show one way, in the rectilineal and parallel groove d¹,
formed on the cylindrical surface of the tube D, to employ which it will be necessary
to remove pin a from engagement with cam groove d and insert the same or a
similar pin in the corresponding screw threaded aperture f¹, where it will prevent
rotary movement of the cam tube, while permitting free longitudinal linear motion.
In ordinary use aperture 1 should preferably be kept closed by a stop plug flush
with the inner surface of the shell A, so as not to impede the free movements of
tube D, and to retain the lubricating material, for the introduction of which the
necessary apertures are provided.
The extremities of pin a, and projections 61 61 may be armed with anti-friction
rollers or other well known anti-friction appliances, when deemed desirable.
In case still more complex movements of the valve should be desired under
peculiar conditions, two or more of the above described devices may be employed
on the same valve rod, in series, whose conjoined and combined movements may
thus be transmitted to the valve, or valves, but the means and apparatus above
described are sufficient for all ordinary and useful purposes.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
1. An auxiliary gear for the valve motions of reciprocating engines, consisting of
a cam tube having cam grooves in its inner and outer surfaces interposed between
sections of the rod or means connecting the reciprocating valve with the rocker
arm or other source of motion, whereby a useful irregularity is imparted to the
movements of said valve, substantially as specified.
2. In combination with the reciprocating valve of an engine, and the rocker arm
transmitting motion thereto, a tubular rotary cam interposed between the same,
in the connection thereof, said cam having an irregular cam groove or grooves in
its outer surface, co-operating with a fixed controlling means, as a guide pin,
whereby the rectilinear to-and-fro movements imparted to said tubular cam by the
rocker arm rod are converted into irregular combined rotary and forward and back
movements, which in turn are conveyed to the valve rod and converted into
irregular to-and-fro, linear movements through a suitable connection, substantially
as specified.
3. In combination with the reciprocating valve of an engine, and the rocker arm
transmitting motion thereto, a tubular rotary cam interposed between the same, in
the connection thereof, said cam having an irregular cam groove or grooves in its
outer surface, and also an irregular cam groove or grooves in its inner surface; the
former co-operating with a fixed controlling means as a guide pin, and the latter
co-operating with engaging means borne on the head of the valve rod, whereby the
rectilinear to-and-fro movements imparted to the said tubular cam are converted
into irregular combined rotary and forward and back movements, which are
transmitted to the valve rod through the medium of the inner cam groove or grooves
and its connection with the said valve rod, and modified into compound irregular
to-and-fro linear movements and thence transmitted to the valve, substantially as
described.
4. As an improvement in auxiliary gear for valve motions the combination of
stationary shell A, valve rod B, rocker arm rod C, tubular rotary cam D, having

page_text: cam grooves d, e, guide pin a, swivel connection c, and rod head b with
projections 6 61, substantially as specified.
5. A tubular cam for valve gears consisting of tube D, having exterior cam
groove d formed on its outer surface and interior cam groove e, formed on its inner
surface, in combination with means for reciprocating the said cam and for 5
transmitting the irregular motions occasioned thereby, substantially as specified.
Dated this 10th day of October 1808
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicants.