Year: 1899

page_text: Date of Application, 20th Jan., 1899
Complete Specification Left, 19th Oct., 1899-Accepted, 25th Nov., 1899
I, FREDERICK Hugh Smith, of The Limes, Dumblane, North Britain, Engineer,
do hereby declare the nature of this invention to be as follows:-
This invention relates to two stroke cycle engines having a supplementary
piston to expel the products of combustion. I interpose a spring between the
two pistons, and provide a non-return valve preferably in the supplementary
piston. On the explosion taking place, the two pistons are forced out together
but on opening the exhaust valve at the inner end of the cylinder, the pressure is
reduced, and the spring causes the return of the supplementary piston before
the other, so expelling the products of combustion. Meanwhile the main piston
has uncovered an inlet passage in the outer end of the cylinder, and a charge is
admitted into the space between the pistons. The return of the main piston com-
presses this charge, and forces it through the valve in the supplementary piston,
into the combustion chamber.
I, FREDERICK HUGH SMITH, of The Limes, Dumblane, North Britain, 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-
This invention relates to two stroke cycle engines having a supplementary piston
to expel the products of combustion.
I provide a spring tending to force the supplementary piston towards the inner
end of the cylinder and provide a non-return valve preferably in the supplementary
piston.
Figure 1 is a longitudinal section of an engine constructed according to this
invention. Figure 2 shows a modification.
a is the cylinder and is the main piston in it. c is the connecting rod pivotted
to the piston b and the crank d on the crank shaft e. f is a cam fixed to the
crank shaft e and operating the exhaust valve g through the lever / pivotted at j.
is the admission pipe and port supplying an explosive mixture of air and gas or
I is a valve which is preferably provided on the pipe k. m is the supple-
vapour.
mentary piston having a non-return valve n in it which is normally held onto
Price d

page_text: its seat by the spring o. p is a spring interposed between the pistons b and m
and tending to separate them as shown in Figure 1 or it may be placed outside the
cylinder as shown in Figure 2. is the ignition apparatus of any ordinary
construction.
The working of the engine is as follows:-
On the explosion taking place the two pistons b and m are forced out together,
but on opening the exhaust valve g at the inner end of the cylinder, the pressure
is reduced, and the spring p causes the return of the supplementary piston m
before. the other, so expelling the products of combustion. Meanwhile the main
piston has uncovered the inlet passage k in the outer end of the cylinder, and a
charge is admitted into the space between the pistons. The return of the main
piston compresses this charge and forces it through the valve n in the supple
mentary piston m into the combustion chamber. The spring may take the form
of an air cylinder.
One great advantage gained by this engine is that it is more or less self govern-
ing for after the exhaust is opened the spring p takes a definite time to carry the
niston m back to the inner end of the cylinder, and if the engine is running too
fast for the piston m to .complete its travel before the exhaust is closed then the
products of combustion are not completely expelled and only a partial charge of
the explosive mixture is drawn in and therefore the faster the engine is running
the smaller and more diluted are the charges supplied to it.
The speed of the engine can be regulated either by adjusting the spring p or by
turning the cock 7.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is;
1. An explosion engine having a supplementary piston with a spring tending
to force it to the inner end of the cylinder, an inlet admitting the charge to the
space between the pistons, an exhaust at the inner end of the cylinder, and a non-
return valve through which the charge compressed between the pistons is forced
into the inner end of the cylinder.
2. Explosion engines substantially as described and illustrated in the drawings.
Dated this 12th dose of Dotahan 1800