Improvements in Valve Gear for Gas or Oil Motor Engines.
Year: 1895

page_text: Date of Application, 21st June, 1895-Accepted, 27th July, 1895
COMPLETE SPECIFICATION.
Improvements in Valve Gear for Gas or Oil Motor Engines.
I, HENRY PERCY HOLT, of No. 22 Chancery Lane, in the County of London,
Engineer, 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 :-
My invention relates to apparatus for working the exhaust valve of a gas or oil
motor engine operating on the Otto cycle, dispensing with the ordinary half speed
countershaft, and utilising the gear for regulating the speed of the engine, as I shall
describe referring to the accompanying drawings.
Fig. 1 is a plan, partly sectional, of the exhaust valve and the gear for working
it, the regulation being effected by an inertia governor.
Fig. 2 shews the gear modified so that the regulation is effected by a centrifugal
governor.
Referring first to Fig. 1, V is the exhaust valve which is usually kept closed by
a spring S. On a bracket B projecting from the cylinder of the engine I pivot a
bell crank lever, one arm L of which has an undercut notch N, and its other arm M
has screwed through it an adjustable pusher A. provided with a lock nut. To M
is pivotted a link C connecting it to a radius R which is pivotted on the bracket B
and is parallel to M.
On the end of the arm M is also pivotted a lever one arm D of which terminates
in a hook E, another arm is a weight W, and the third arm F' is pressed by spring G
adjustable by a nut H against the tail I of the link C.
K is a blade projecting from a rod P which, by means of a crank, excentric or
cam, is made to reciprocate making a to and fro stroke during each revolution of
the crank shaft of the engine.
The lever L M has applied to it an adjustable spring T which tends to bring it
to the position shewn, this spring however being not sufficiently strong to overcome
the spring S. As the rod P makes its stroke to the left, the end of the blade K
engaging the notch N moves the lever L M so as to open the valve V, the hook E
being thus moved to a position such as E' beyond an undercut projection Q forming
a catch.
As P retreats to the right, the spring S closes the valve V pushing M back to
the position shewn. Should the engine be running at normal speed, the weight W
moving with the arm M retains its position relatively to M, and the hook E as it
retreats escapes Q. If however, owing to excessive speed of the engine, the
retreat of M is so rapid that the weight W lags behind, then the hook E is made
to engage the projection Q, and the valve V is thus held open until the speed of
the engine becomes normal. In any case, whether the speed is normal or not the
momentum of the lever L M and parts connected to it is such as to carry the
notch N so far to the right that, when the next stroke of P to the left occurs,
the blade K passes along the end of L without encountering the notch N, and
consequently the valve V is not again opened till the parts having become quiescent
in the position shewn, the following stroke of P to the left causes the opening
of V, which is thus made to open only at every alternate revolution of the engine
haft.
As shewn in Fig. 2 the lever arm D is connected to the sliding part of a cen-
rifugal governor in such a manner that, when the speed of the engine is too great,
he hook E in its back stroke engages the catch Q and the exhaust valve is thus
eld open until the speed of the engine becomes normal.

page_text: Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, I declare that what I claim in
respect of valve gear for gas or oil motor engines working on the Otto cycle, is :—
1. In combination with a rod and blade caused to reciprocate once in every
revolution of the crank shaft a spring bell crank lever one arm of which presents a
notch to engage the reciprocating blade, its other arm having an adjustable pusher
which bears against the stem of the exhaust valve, arranged and operating sub-
stantially as described.
2. In combination with the exhaust valve gear, an inertia governor arranged so
as to hold the valve open in case of excessive speed, substantially as described.
3. In combination with the exhaust valve gear, a lever connected to a centrifugal
governor and adapted to hold the valve open in case of excessive speed, sub-
stantially as described.
Dated this 20th day of June 1895
ABEL & IMRAY,
Agents for the Applicant.