An Improved Rotary Engine.
Year: 1894

page_text: Date of Application, 17th Feb., 1894
Complete Specification Left, 30th July, 1894-Accepted, 1st Sept., 1894
PROVISIONAL SEMIFIATION.
An Improved Rotary Engine.
I ANDREW TONKIN of 11 Alexandra Road Thames-Ditton Surrey Engineer
hereby declare the nature of this invention to be as follows:-
do
This invention relates to an improved rotary engine designed to work economically
at a high speed. The engine has a radial piston carried by a hub revolving
concentrically within a cylindrical chamber. The annular steam space between the
hub and the cylinder is traversed by a sliding abutment which interrupts the
continuity of the steam space between the induction and eduction passages and is
This abutment
retracted at the proper moment to allow the radial piston to pass.
receives reciprocating motion preferably in the direction parallel to the piston shaft
which is preferably the direction of least width of the annular steam space although
it might be otherwise and the motion of the abutment might be radial, the abutment
being in either case reciprocated by lever or other connections operated from a cam
or its equivalent on the engine-shaft.
An essential feature of the invention is that the abutment is also the steam-
distributing valve by which the admission and cut-off are regulated.
For this purpose it is fitted to slide over suitable ports in a valve chest and is
provided with a passage or passages through which the steam enters the cylinder
when the abutment is in position therein, the steam issuing from the side of the
abutment opposite to that at which the exhaust passage is situate.
In order to vary the point of cut-off, an expansion valve may be combined with
the valve abutment, operated through any suitable expansion gear.
The piston and abutment are, of course, suitably packed, to ensure steam-tight
joints with the cylinder.

page_text: within a cylinder C, and the annular steam space between the hub B and the
circumference of the cylinder C is traversed by a sliding abutment D which
interrupts the continuity of the steam space E between the induction and eduction
passages F, G and is retracted at the proper moment to allow the radial piston A
to pass. This abutment receives reciprocating motion in the direction parallel to
the engine shaft H which is preferably the direction of least width of the annular
steam space E, the abutment being reciprocated by a crank pin I or a cam or its
equivalent on the engine shaft H.
An essential feature of the invention is that the abutment is also the steam-
distributing valve by which the admission and cut-off are effected.
For this purpose the abutment is made in the form of a plunger and is fitted to
slide in a chest or cylinder J opening at its inner end to the steam space E so that
the abutment may be projected from its casing J completely across the cylinder C
in which position its inner end enters a cavity J in the opposite end of the
cylinder C. The abutment is provided with a steam passage d which traverses the
abutment in such direction that when the abutment projects completely across
the steam space E the outer end of the port d eoincides with the steam induction
port F whilst the inner end of the port or passage à opens through the valve to the
steam space E at the opposite side of the abutment or valve to that at which the
eduction passage G is situated. Steam then enters the cylinder and presses against
the piston A which has just passed beyond the point at which the abutment is
situated.
The combined valve and abutment enters the cavity J¹ to a depth equal to the
length of the port F so that on the abutment being retracted to give passage to the
piston A the admission of steam will be cut off before the steam space E ceases to
be divided by the abutment D.
In order to vary the point of cut-off, an expansion valve operated through any
suitable expansion gear, may be combined with the valve abutment by being
interposed between it and the induction port F.
The piston and abutment are, of course, suitably packed, to ensure steam-tight
joints with the cylinder. This is effected by providing the hub B with packing
rings bb bevelled and seated in corresponding grooves in the ends of the hub so as
to bear against the ends of the cylinder and by providing the piston A with side
packing strips a a and a cross packing strip a¹ received in grooves in the edges of
the piston and pressed outwards against the ends and circumference of the cylinder
by springs a the cross strip a¹ not being in the same plane as the side strips a so
that the ends of the former will cross the ends of the latter and make a tight joint
at the corners of the piston.
The valve D is similarly packed by means of longitudinal strips p received in
grooves in its sides and pressed outwards by springs p₁ so as to make contact with
the cylinder C on one side and the hub B on the other, the valve cylinder J and
the corresponding cavity J1 in the opposite end of the cylinder into which the valve
projects being packed by circumferential packing rings d' embracing the valve and
formed of inner rings of gun metal held up by outer rings of cast iron.
In the engine illustrated the valve receives its reciprocating motion from a crank
pin I acting through a link K on a cross head L sliding in a guide M and having a
projecting stud engaging in a longitudinally slotted lever N pivoted to the base
plate at n and coupled by a link O to the valve.
The slot in the lever is straight for about 3rds of its length and is curved at the
lower end where it approaches the pivotal centre n. When the valve is in the
position shown the stud is in the straight portion of the slot in the lever N which
then coincides in direction with the slot of the cross-head guide M and a prolonged
dwell of the valve in this position is ensured to enable it to fulfil the function of an
abutment for the steam, but as soon as the stud is caused by the motion of the
cross-head L to enter the curved part of the slot the lever N is oscillated on its
centre as shown in dotted lines in Figure 2 and the valve is quickly withdrawn
from the cylinder C to give passage to the piston A after which by the reverse

page_text: motion of the cross-head and stud, the valve is quickly returned to position in the
cylinder to act again as an abutment during the next revolution of the piston and
so on. It is to be understood that I do not limit myself to the means described for
operating the combined valve and abutment but may adopt any suitable mechanism
for communicating motion to it at proper times from the main shaft.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. In a rotary engine the combination with the cylinder and with a radial piston
and hub working concentrically therein, of a combined abutment and steam
distribution valve adapted to be moved into position to divide the steam space and
out of position to give passage to the piston as described, said valve being provided
with a port or passage whereby to control the admission of steam to the cylinder,
substantially as specified.
2. In a rotary engine the combination with the combined abutment, and steam
distribution valve fitted to operate as described of means for actuating the same
from the main shaft so as to bring it into position to act as an abutment for the
steam during the greater part of the revolution of the piston and to be retracted at
the proper moment to cut off the steam admission and give passage to the piston as
specified.
Dated this 30th day of July 1894.
By A. M. & Wm. Clark,
A. TONKIN,
53, Chancery Lane, London, Chartered Patent Agents.