Year: 1887

page_text: Date of Application, 2nd Sept., 1887
Complete Left, 4th June, 1888
Complete Accepted, 6th July, 1888
I, JAMES ATKINSON, of 3 Nassington Road, Hampstead, London, N.W. do hereby
declare the nature of this invention to be as follows:-
In Letters Patent No. 3,52286 granted to me I described a gas engine in which the
single-acting piston was caused to make four strokes for each revolution of the crank
shaft, one for drawing in the explosive mixture, one for compressing it, one for
performing work, due to its ignition and expansion, and one for the exhaust; I also
described in the above mentioned patent that the expansion stroke was made longer
than the drawing in stroke, so as to obtain the benefit of carrying this expansion to
any desired extent. This invention is for the purpose of making the amount of
expansion variable whilst the engine is running.
This expansion may be varied by altering the position of the crank shaft contro, the
position of the centre pin I (see the drawings illustrating the above mentioned patent)
or the length of the crank rod E. Probably the most convenient method to adopt
would be to alter the position of the centre pin I and it can be performed in a
convenient manner by the arrangement now to be described.
As these engines have been hitherto constructed, the centre pin I, (on which the
vibrating lever H vibrates,) has been a straight pin or shaft driven tightly into the
framing. Instead of this being a straight pin or shaft it may be formed with
excentric portions on each end where secured in the framing, the excentric portions
being on the same axial line which is parallel to the axial line of the centre pin I-if
the pin is revolved on these excentrics ends the position of the centre pin I will be
altered as desired; for the purpose of revolving this shaft it may have one of the
excentric ends continued through the framing on one side on which a worm wheel is
fitted, a worm in gear with this worm wheel being fitted to a suitable shaft having a
hand wheel in any convenient position; cod pieces may be fitted in the frame so as to
bear on the excentric ends, having set screws arranged so that when screwed up they
will keep the centre pin I secure and firm.
The variable expansion may be caused by other means and 1 do not confine myself
to the above mentioned method only, it however appears to me to be a very suitable
arrangement as it is substantial and if properly designed it can be made to reduce the
space into which the charge is compressed when the charge is correspondingly
reduced in volume, so that practically the same compressing pressure is obtained.
Dated this Second day of September 1887.

page_text: 1, JAMES ATKINSON, of 3 Nassington Road, Hampstead, N.W. 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 :-
In Letters Patent 35228 granted to me I described a gas engine in which a single
acting piston was caused to make four strokes for cach revolution of the crank shaft;
one for drawing in the explosive mixture, one for compressing it, one for performing
work due to its ignition and expansion, and one for the exhaust; I also described in
1 above mentioned patent that the expansion was made longer than the drawing in
stroke, so as to obtain the benefit of carrying this expansion to any desired extent.
This invention is for the purpose of making the amount of the expansion variable
by substantial means which will not interfere with the stiffness so essential to the
satisfactory working and durability of a gas engine, and for satisfactory means whereby
the expansion can be readily altered either whilst the engine is at rest, or when
running, also for certain locking arrangements whoroby this rigidity is obtained.
The means by which this invention is carried out are shown in the accompanying
drawing, in which sheet 1, Figs. 1, 2, 3 and 4 are diagrammatical illustrations of an
engine constructed under above Letters Patent. Fig. 1 being the end of the exhaust
stroke, Fig. 2 the end of the suction stroke, Fig. 3 the end of the compressing stroke,
and Fig. 4 the end of the working stroke. Sheet 2, Figs. 5, 6, 7 and 8 are similar
illustrations showing the amount of expansion varied in the manner hereinafter
explained. Sheet 3, Figs. 9 and 10 show enlarged views of a suitable manner for
carrying out this invention. In these illustrations, as also in those shown in letters
patent No. 35228 like letters are applied to similar parts.
In a gas engine constructed in accordance with Letters Patent No. 352288 the
expansion may be varied by altering the position of the crank shaft centre, the
position of the centre pin I, or the length of the crank rod E; as was explained in
above quoted Letters Patent. Probably the most convenient method to adopt would
be to alter the position of the centre pin I, and it can be performed in a convenient
manner by the arrangement now to be described.
As these engines have been hitherto constructed the centre pin I (on which the
vibrating lever H vibrates), has been a straight pin or shaft driven tightly into the
framing. Instead of this being a straight pin or shaft it may be formed with eccentric
portions on each end, where secured in the framing, the eccentric portions being on
the same axial line which is parallel to the axial line of the centre pin I, if the pin I
is revolved on these eccentric ends its position will be altered as desired; in sheet 3
figure 10 one end of this centre pin is shewn, the eccentric portion T passes through
the framing of the engine and has on its outer end a suitable worm-wheel gearing
into which is a worm U the shaft of which is carried in suitable brackets fixed to the
framing also carrying on its shaft a hand wheel V by means of which the centre pin I
can be revolved on the eccentric ends T. The other end of the centre pin I is

page_text: provided with a similar eccentric end to that shewn, or it may be larger in diameter
so that the centre pin I and ends T as a whole may be inserted from the other side.
To secure the vibrating pin I securely in the framing so as to give the necessary
solidity and stiffness essentially necessary to satisfactory working, the openings in the
frame through which the eccentric ends T pass are provided with cod pieces W which
(excepting when it is necessary to alter the ratio of expansion) are screwed firmly
down upon these eccentric ends by means of the set screws X.
The diagrammatical views in sheet 1 shew the various capacities of the cylinder
when the centre pin I is in one position and those in sheet 2 shew other capacities
giving a different ratio of expansion when the centre pin I is moved further away
from the crank shaft by means of the eccentric ends T. From an inspection of figure 1
sheet 1 and fig. 5 sheet 2 it will be seen that the piston is close to the end of the
cylinder, thus the whole of the residuum from the previous working stroke is practically
expelled in both instances; comparing fig. 2 sheet 1 with fig. 6 sheet 2 it will be
seen that in the latter instance a greater volume of charge is drawn in, fig. 7 sheet 2
shews a somewhat larger space than is shewn in fig. 3 sheet 1, thus allowing for a
somewhat similar amount of compression, the volumes to which these respective
charges are expanded are shewn in fig. 8 sheet 2 and fig. 4 sheet 1 being practically
the same.
It will be seen that when the engine is working with the centre pin I in
the position shewn in figs. 5, 6, 7 & 8 sheet 2 a greater amount of power will be
given out though working with a less ratio of expansion than when working with the
centre pin I in the position shewn in figs. 1, 2, 3 & 4 sheet 1.
With a little care the shifting of the centre pin I can be so arranged as to produce
such variations in the ratio of the expansion or the amount of the compression as may
be desired.
I wish it to be understood that I do not confine myself to the particular arrangement
described and illustrated as it may be varied by means well known to Engineers.
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. The general arrangement & construction of parts of a gas engine whereby the
ratio of expansion may be varied as described and illustrated in sheets 1, 2, 3 of the
accompanying drawings.
Dated this 2nd day of June 1888.
Witness,
G. E. PRIDDLE,
60, Mansfield Road, N.W.
JAMES ATKINSON.