Improvements in Gas and Petroleum Engines.
Year: 1889

page_text: COMPLETE SPECIFICATION.
Improvements in Gas and Petroleum Engines.
I, OTTO LINDEMANN of No. 86 Queen Street, Cheapside London in the county of
Middlesex 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 an improved mechanism for obtaining intermittent action
of the valves and other parts of a gas or petroleum engine, whereby the rotary
motion of the main shaft is directly employed to give a reciprocatory motion to the
valves or other parts at every two or more revolutions of the main shaft.
The reciprocatory motion is obtained by means of a connecting rod attached to an
excentric or crank pin on the main shaft, and to obtain the intermittent action of the
valve, instead of connecting the aforesaid rod directly to the spindle or lever of the
valve, I employ between the two a movable disc having on its edge alternate pro-
jections and depressions, which is rotated by a pin and star wheel in such a way
that during one revolution of the main shaft one of the projections on the disc comes
into contact with the spindle or lever of the valve and permits of motion being
communicated to the latter, while during the following one or more revolutions, one
of the depressions on the disc being brought opposite the spindle or lever of the valve,
no contact is obtained, and therefore no motion is communicated to the valve. The
valve or other part desired to be actuated may thus be moved during one revolution,
and left standing still during one or more revolutions of the main shaft, the periodical
movement of the valve being made according to the arrangement of the projections on
the disc aforesaid.
In the invention herein described I make use of the elliptical motion of a connecting
rod attached to a crank pin or excentric on the main shaft, both to give the required
reciprocating motion to the valve and at the same time to rotate the disc by means of
the pin and star-wheel before mentioned, so that the reciprocatory motion of the
connecting rod shall be communicated to the valve only at certain definite periods.
The mechanism may be so arranged that the disc and star wheel are attached to
the engine framing, and are moved round a certain distance by a pin on the con-
necting rod engaging the teeth of the star-wheel at each revolution; or, the pin may
be fixed to the engine framing and the disc and star-wheel may be connected to and
move with the connecting rod in an elliptical line as before described.
In the accompanying drawings the latter arrangement is shewn, the motion of the
connecting rod being obtained by means of an excentric fixed to and revolving with
the main shaft.
Having explained the nature of my invention I now proceed to describe with
reference to the accompanying drawings the manner in which the same is to be
performed.
'
In Fig. 1, A is the main shaft of the engine, B the excentric with its connecting
rod, C the exhaust valve to which the periodical movement is to be communicated;
D is the movable disc with the projections Y and the depressions X; F the star-
wheel, formed in one piece with the disc D; H is the pin fastened to a lever and held
down by a spring L, so that it can engage gradually yet completely with the star-
wheel F.
The action of the mechanism is as follows; the lower half only of the vertical
movement of the excentric rod is employed to open the valve C; the upper half and
the side movement serve for the rotation of the disc D, by bringing the star-wheel
gradually into contact with the pin H, after the excentric rod is released from contact
with the spindle or lever of the valve. As the excentric rod continues its upward
movement, the pin H remains in contact with the star-wheel F and rises with it,

page_text: turning the wheel and disc partly round, and being released only when the excentric
rod has reached its maximum side motion in the opposite direction, when the pin H
is set free and the excentric rod commences the lower half of its down motion towards
the valve C.
The excentric rod B is here shewn as being bored longitudinally throughout its
length and forming a guide for the spindle which transmits the downward_motion to
the valve C. So long as one of the depressions or recesses X in the disc D, remains
opposite the end of this inner spindle, the outer hollow excentric rod B simply slides
over the inner one without imparting any motion to it, but when one of the pro-
jections Y on the disc is exposed, the inner spindle is pressed down to an extent
corresponding to one-half of the vertical movement of the excentric B, and the
valve C is then opened.
When the engine is working at full power this opening and closing of the valve
will take place regularly at every two or more revolutions of the main shaft, and an
impulse will be imparted to the flywheel accordingly by the regular explosion at
definite intervals of the gaseous mixture in the cylinder. Where the work on the
engine varies it is necessary in order to regulate the speed of the engine to reduce the
number of explosions when working under full load, and this is effected by detaining
the exhaust valve ( when open so as to prevent its closing again until the flywheel
requires another impulse. The result of keeping the valve C open is to prevent fresh
mixture being drawn into the cylinder to form an explosive charge.
The detention of the valve Cis effected in the following manner; in Fig. 2, D is a
weight connected to the excentric rod B and describing a circle round the point A.
Attached to the weight D is a rod H sliding in guides on the excentric rod B. The
rod H prevents any side movement of the weight D apart from the excentric, but
permits of vertical movement, and the weight D is prevented from falling only by the
spring E above it, which holds it up. When the speed of the engine rises above its
normal rate, the centrifugal force acting on the weight D causes it to overcome the
tension of the spring E and hang back during the upward or return motion of the
excentric, thereby depressing the rod H, which acts on the bell crank K L and brings
the catch N over the notch M on the exhaust lever F G. The catch N is pivoted to
the engine framing at O, and when engaged in the notch M prevents the exhaust
valve C from being closed by the tension of the spring Q.
By this means I keep the exhaust valve C open so long as the rate of speed of the
engine is above the normal, and during this time no explosive charge is drawn into
the cylinder. When the speed of the engine has again dropped to its normal level, the
tension of the spring E being then greater than the centrifugal force acting on the
weight D, the rod His drawn back and the catch N falls clear of the notch M, so
that the exhaust valve and its lever F G are again free to be acted upon by the
excentric B, which then opens and closes the exhaust valve C periodically as before
described.
In Fig. 3 shew the complete arrangement of mechanism for obtaining the
periodical opening of the exhaust valve, and for holding it open during such time as
the engine runs above its normal rate of speed. The same arrangement can also be
applied to horizontal engines.
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. The employment in gas and other engines of a movable disc having alternate
projections and depressions for the purpose of imparting intermittent reciprocatory
motion to valve rods or other parts at every two or more revolutions of the main
shaft.
2nd. The employment of an excentric and rod as herein described and illustrated
in the accompanying drawings for the purpose of carrying and rotating the disc and
star-wheel.

page_text: 3rd. In combination with the above, the arrangement of a lever held down by a
spring L and carrying a pin H which engages the star wheel F, as herein before
described and illustrated in Fig. 1 of the accompanying drawings.
4th. In combination with the above, the employment of a governor weight D
attached to the rod B and acting upon a catch N, as herein before described and
illustrated in Fig. 2 of the accompanying drawings, for the purpose of holding the
exhaust valve open when the engine is running above its normal speed.
5th. The special construction and arrangement of the whole of the mechanism
substantially as and for the purpose above described.
Dated this 16th day of October 1889
OTTO LINDEMANN.