Year: 1887

page_text: Date of Application, 15th Feb., 1887
Specification Accepted, 10th Feb., 1888
I, JOSEPH THOMAS, of 30, Charles Street, Cardiff, in the County of Glamorgan,
Builder, 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 said invention relates to certain improvements in engines driven by gas, steam,
petroleum and the like and relates chiefly to a new construction of piston and the
operation of the same.
According to this invention the piston will be moved, by the explosion of gas or
otherwise, forward and backward within the cylinder along either a straight or screwlike
path and will impart to the shaft a rotary motion.
The shaft is fixed laterally but is free to rotate and receives the revolutionary
motion from an arm or stud, keyed upon it, which is worked by a spiral groove sunk
in the internal surface of the piston.
I will now describe my invention with reference to the accompanying drawings and
to the Figures and letters marked thereon.
Figures 1 and 2 show in plan and side view respectively a piston and shaft constructed
and arranged according to my invention and Figure 3. is an end view of the same
and cross section of cylinder.
The two circular piston faces a. b. which carry the packing rings are respectively
cast with tubular protrusions a¹ 6' in form as shown in Figures 1. and 2, and are held
in position, apart from each other, by means of the tubular piece c. which is bolted or
otherwise attached to them.
In the centre of this piston is the shaft d. carrying a fixed arm or stud e. provided
at its outer end with an antifriction roller el projecting into the space or groove
between the two tubular pieces a¹ 6¹. The arm or stud e. is shown in dotted lines
Figure 2. and in detail in Figure 8.
g. working
The piston is prevented from turning in the cylinder by a rib or feather
in a groove cut in the internal surface of the cylinder A, as shown in Figure 3.
It will be seen that during the first or forward half of the stroke the edge of the
tubular piece b' acts upon the arm e. causing it to turn the centre shaft d. while
during the second or return half of the stroke the edge of the tubular piece a¹ forces
the arm up to its original position, the shaft is thus caused to make a complete
[DC]

page_text: revolution during each stroke. In making the revolution the stud e. travels through
the whole of the endless space between the pieces a¹ b¹.
Instead of casting two tubular pieces a¹¹ they may be cast in one piece a. with
one end open (as shown in Figure 7) and a groove be cut in the internal surface for
the reception of the arm e.
The end b. will then be screwed or bolted on, to complete the piston, the operation
of the same being as before described.
When a high speed is required I use the piston shown in Figure 5. in which an
additional groove is cut upon the outer surface in the reverse direction to that in the
interior. The arm e. upon the shaft d. works in the inner groove, and a stud h. with
roller i. is passed through the cylinder into the outor groove on the piston which, in
this case, is made without any rib or feather and being deflected by the stud h. revolves
as it moves forward and backward, the shaft thus makes two revolutions to each stroke
of the piston.
In Figure 4. is shown another form of piston made solid and keyed loosely to the
centre shaft so as to slide, but not turn, thereon. This piston has an external groove,
only, and a screw like motion, being deflected by a stud, passed through the cylinder
coming in contact with the sides of the groove; the shaft makes one revolution to
each stroke of the piston.
For a slow motion I use the piston shown in Figure 6. which is made with the
groove running twice up and down its length so that the piston has to make two strokes
to each revolution of the centre shaft d.
When an engine to be worked by steam is constructed according to this invention
there may be keyed loosely upon the centre shaft at each end of the cylinder a valve,
as shown in Figure 9, the said valve making the same number of revolutions as the
shaft, the hole d³ at each end of the stroke opening the inlet and exhaust ports
alternately. The piston will in this case receive a fresh impulse at each end of the
stroke.
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 :-
First. In engines of the nature hereinbefore referred to, the construction, combi-
nation and arrangement of the piston and shaft d. having an arm or stud e. within
the cylinder, substantially as hereinbefore described and illustrated by Figures 1. 2.
and 3. of the accompanying drawings.
Secondly. In engines of the nature referred to in the previous claim, the modified
form of piston and the arrangement thereof in connection with the central shaft and
a stud projecting from the inner face of the cylinder, substantially as hereinbefore
described with reference to Figure 4. of the accompanying drawings.
Thirdly. In engines of the nature referred to in the previous claims, the modified
form of piston having internal and external grooves, and the combination and arrange-
ment of the same in connection with the shaft d. having an arm or stud e, and the
stud h. projecting from the inner face of the cylinder, substantially as, and for the
purpose, hereinbefore described and shown at Figure 5. of the accompanying
drawings.
And Fourthly. In engines of the nature referred to in the previous claims, the
modified form of cylinder, substantially as herein before described with reference to
Figure 6. of the accompanying drawings.
Dated this Second day of February 1888.
VAUGHAN & SON,
Agents for the Applicant.