Improvements in Gas Motors.
Year: 1889

page_text: Date of Application, 2nd July, 1889
Complete Specification Left, 1st Apr., 1890-Accepted, 3rd May, 1890
PROVISIONAL SPECIFICATION.
Improvements in Gas Motors.
I, WILLIAM THOMAS ROWDEN, of Lenzio in the County of Dumbarton, North
Britain, Professor of Applied Mechanics in the Glasgow and West of Scotland
Technical College do hereby declare the nature of this invention to be as follows:-
My said invention is an improvement in the motor described in my specifications
No. 9705 A.D. 1888, and my improvement consists in constructing the link which
there connects the two cranks, so as to be adjustable in length, for the purpose of
modifying the volume of the charge and the extent to which the exploded gases are
expanded in the cycle of the engine.
In the above named specifications it is stated that the ratios of the volumes of the
gases at the ends of the four parts of the cycle, viz. at the ends of compression, expan-
sion, exhaust, and take-in, depended upon the ratios of the lengtbs of the different
parts of the combination and the relative positions of the two shafts, but it was not
claimed that these ratios were made adjustable so as to give different results in the
same engine.
The mode of making the link adjustable in length is a matter of indifference as far
as my invention is concerned, and many well known devices are available.
If the cranks, shafts, and other parts be arranged as shown in the drawings accom-
panying the above named specifications the lengthening of the link will cause an
increase in the volume of the combustible charge and a decrease of the volume at
the end of expansion without any considerable alteration in the other parts of the
cycle.
But these particular relative positions are by no means essential to the invention.
Another arrangement of the parts of the same combination may be made by con-
necting the connecting rod of the front piston with the crank on the fly wheel shaft,
and the connecting rod of the back piston with the other crank, the latter rod being
placed on the side of the cylinder opposite to that shown in the drawings.
The second cheek of the double cheek crank would then require to make an angle
with the first cheek on the opposite side to that on which is shown in the drawings,
and the lines of the shafts would be altered so as to put the fly wheel shaft in the same
relative position to the cylinder and front piston as in ordinary steam or gas engines,'
the other shaft being put higher and more remote from the pistons & cylinder than the
fly wheel shaft, revolution being in the same direction as before and as shown by the
arrow.
With this arrangement the lengthening of the connecting link would have the same
effect as before described, and shortening, a contrary effect.
Thus if the parts be designed so as to give an expansion-to a volume about equal to
the volume after the take-in portion of the cycle so as to get a large power out of the
engine irrespective of economy, when the engine is required to develope less power,
the link may be shortened and it will take in a less charge and work more
expansively.
Dated this First day of July 1880

page_text: Technical College 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 is an improvement in motors actuated by the inflammation of mixtures
of inflammable gases or vapours and atmospheric air, constructed in accordance with
my specification numbered 9705,, A.D. 1888, and the improvement consists in con-
structing the link which connects the two cranks so that it may be adjusted in length
for the purpose of readily modifying the amount of the charge and the extent to which
the gases are allowed to expand after their inflammation or explosion.
In the above named specification it is stated that the ratios of the volumes of the
gases at the ends of the four parts of the cycle of the engine, namely, at the ends
of (1) expansion, (2) exhaust, (3) intake, and (4) compression, depend upon the
ratios of the lengths of the different parts of the combination and the positions of
the two shafts, but it was not claimed that any of the parts were made adjustable
so as to give different volumetric ratios in the same engine after they had once been
fixed.
The mode of making the link adjustable in length is a matter of indifference as
far as my invention is concerned, and many well known devices are available.
For applying the adjustable link I prefer the arrangement of parts as shown in the
accompanying drawings where the front piston is connected to the pin B of the double
cheek crank on the shaft A which carries the fly wheel, and the back piston to the
pin E of the crank on the free shaft D, by the return connecting rod, of which a part
is shown in the plan.
The relative lengths and the relative positions of the various parts are shown in the
skeleton elevation where the cranks are represented by heavy full lines and the link
which is adjustable in length by a heavy broken line.
With such positions and dimensions and with the necessary amount of clearance
between the pistons at the end of the exhaust part of the cycle, the relative volumes
at the ends of (1) expansion, (2) exhaust, (3) intake, and (4) compression, differ but
little from those obtaining in engines that expand only to the volume occupied by the
gases immediately before compression commences, but by shortening the link Ethe
volume after (1) expansion is increased, whilst the volumes at the ends of the other
three parts of the cycle are decreased, though the ratios of these three are not
materially changed.
Thus if the normal expansion of an engine be made (say) 50 per cent. beyond
the volume after (3) intake, more power can, if required, be got out of it by
lengthening the link and thus taking in greater charges and working less expan-
sively; whilst on the contrary if less than the normal amount of power be required,
an economy of gas and a steadier working of the engine will be secured by working
more expansively and taking in a greater number of smaller charges, which are
done by shortening the link.
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 :-
In a motor to work with combustible gas or vapour the combination of a link
which is adjustable in length, with the cranks and other parts of the combination
claimed by me in my specification No. 9705 A.D. 1888, for the purpose which I have
above described.