Improvements in Steam, Air, and Gas Rotary Engines, and in Exhaust and Compression Pumps.
Year: 1895

page_text: Date of Application, 17th June, 1895
Complete Specification Left, 17th Mar., 1896-Accepted, 13th June, 1896
PROVISIONAL SPECIFICATION.
Improvements in Steam, Air, and Gas Rotary Engines, and in
Exhaust and Compression Pumps.
JOHN THEODORE HEWITT 11, Venner Road, Sydenham, London S.E. Professor
of Chemistry in the People's Palace Technical Schools Mile End, London E. do
hereby declare the nature of this invention to be as follows:-
(1.) The engine consists of a cylinder with a shaft running centrally through it,
on which is arranged a turbine of one or more screws of increasing pitch. This
may be duplicated allowing the expansive steam or vapour to enter at the middle
of the cylinder and act on contrary screws so that the lateral thrusts may be
balanced and not be received on the bearings.. The steam, compressed air or
other expansible gas or vapour in expanding along these screws will give them a
rotary. motion.
(2.) The same arrangement may be used as a pump for the exhaustion or
compression of gases by communicating a rotary motion to the shaft.
(3.) The engine may be used as a gas engine by introducing a compressed
mixture of an inflammable gas and air into the cylinder instead of steam; the
ignition of the gaseous mixture taking place as it enters the cylinder; the mixture
of gas and air being compressed by pumps of the type described or of the common
piston or plunger type.
(4.) The vapour of an inflammable liquid may be substituted for gas.
(5.) Steam or water may be introduced together with the inflammable mixture.
Dated this Eleventh day of June 1895.
Improvements in Steam, Air, and Gas Rotary Engines, and in
Exhaust and Compression Pumps.
I, JOHN THEODORE HEWITT, of 11 Venner Road, Sydenham, London, S.E.,
Professor of Chemistry in the People's Palace Technical Schools, Mile End,
London, E., 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:-
A rotary steam, air or gas engine according to this invention comprises a cylinder
having running centrally therethrough a shaft on which is arranged a turbine
consisting of one or more screw threads of increasing pitch, the arrangement being
such that steam, compressed air or other expansible vapour or gas in flowing along
the spiral groove between the cylinder, and shaft and screw thread or threads from
an inlet to an outlet opening will act upon the screw thread or threads and so cause
it or them and the attached shaft to rapidly rotate. For the purpose of balancing
lateral, i.e. end ways, thrust of the shaft, the latter may advantageously be provided
with two screw turbines of the kind mentioned-one right handed and the other

page_text: left handed these being so arranged that steam or other motive fluid will enter
between them and act in opposite directions on the screw threads.
Figs. 1, 2 and 3 of the accompanying drawings are respectively a longitudinal
vertical section partly in elevation, a plan, and an end elevation showing a rotary
engine constructed according to this invention. Fig. 4 is a detail view to a larger
scale.
1, 1 are two stationary cylinders connected at their inner or adjacent ends to a
junction piece 2 and provided at their other or outer ends with removable covers 3
having stuffing boxes 3", the junction piece having a lateral branch 2ª for supplying
motive fluid, and the cylinders having near their outer ends lateral branches 1ª for
exhaust of said fluid.
4 is a shaft extending centrally through the two cylinders
and through the stuffing boxes, which may serve as bearings therefor, or additional
bearings may be provided if desired. At each side of the junction piece 2 the
shaft is provided with multiple screw threads 5,-four are shown, that are of
gradually increasing pitch from their inner to their outer ends, so as to provide
spiral passages of gradually increasing size to accommodate the gradually increasing
volume of the expanding motive fluid, and the screw threads at one side of the
junction piece being right handed and those at the other side left handed so that
the streams of motive fluid flowing in opposite directions through the two cylinders
from the space 2 of the junction piece to the exhaust branches 1ª, will, by acting
upon the two sets of screw threads, rotate the shaft in same direction and prevent,
or practically so, any end thrust on the shaft. Between the inner end of each
cylinder and the junction piece 2, there may advantageously be fixed a plate 6
(Figs. 1 and 4) formed with sector shaped holes 6ª equal in number to that of the
screw threads of each set, so that as the shaft rotates, motive fluid will be admitted
in an intermittent manner to the inner ends of the spiral passages between the
screw threads.
As will be obvious, if a rotary motion be imparted to the shaft from an external
source, the arrangement can be used as a pump for exhausting or compressing gases,
the gases being drawn in through the branches 1ª by the revolving screw threads 5
and forced out through the central branch 2. In some cases, as for example when
using apparatus according to my invention as a pump, I may use a single cylinder
with one screw thread, or one set of screw threads on the shaft, but for use as a
steam or compressed air engine I consider it better to use two sets of multiple
threads as shown in the drawings.
An engine such as described can be used as a gas engine by introducing a
compressed mixture of an inflammable gas, or vapour and air into the engine
cylinder instead of steam or other fluid for example air, under pressure, the mixture
of gas and air being compressed by a pump or pumps of the type herein described,
or of the common piston or plunger type, and the ignition of the gaseous mixture
taking place as it enters the cylinder.
Fig. 5 is a vertical section showing a gas or hydrocarbon motor engine according
to this invention.
1 is the engine cylinder having a supply branch 1ª for explosive mixture and an
exhaust branch 1, and fitted with a shaft 4 having multiple screw threads 5 of
gradually increasing pitch from 1 to 1". 7 is a pump cylinder having a suction
branch 7 and, a delivery, branch 7, the shaft 4, which extends through this
cylinder, being provided with multiple screw threads 5" of gradually decreasing
pitch from 7 to 7b. 8 is a nozzle for supplying gas or inflammable vapour to the
suction branch 7ª of the pump, and 9 is a pipe connecting the delivery branch 7b of
the pump to the supply branch 1ª of the engine cylinder. 10 is a non-return valve
opening inwards and controlling an opening 11 in one of the cylinder covers 3
through which a flame from a burner 12 can be drawn into the cylinder 1 by
suction, at the starting of the engine. 13 is a pulley fixed on the shaft 4 between
the cylinders 1 and 7.
To start the engine, the shaft 4 is rotated by the pulley 13 whereupon air and
gas or vapour will be drawn into the cylinder 7 through the inlets 7 and 8,

page_text: compressed by the screw threads 5* in cylinder 7, and delivered through the
branch 7, pipe 9 and supply branch 1 to the left hand end of cylinder 1.
Simultaneously with the compression of gas and air in cylinder 7, the left hand
end of the cylinder 1 will be exhausted by the screw turbine therein even more
quickly than explosive mixture will be supplied by the pipe 9, with the result that
the flame from the burner 12 will be drawn into the cylinder 1 and ignite the
mixture of gas and air therein. By this means the pressure in cylinder 1 will be
raised considerably above the atmospheric pressure so that the valve 10 will be
closed and the gases expanding along the cylinder 1 will act upon the screw blades 5
and rotate the shaft, whereupon the driving of the shaft 4 by the pulley 13 is
stopped. The motion of the shaft 4 being communicated to the screw threads or
turbine in cylinder 7, a further quantity of gas and air will be delivered along
pipe 9 to the cylinder 1 and burnt therein, so that the motion of the shaft 4 will be
inaintained until the supply of inflammable gas or vapour is cut off. If desired a
plate similar to that shown in Fig. 4 but having an odd number of sector shaped
holes for an even number of screw threads may be fixed in the cylinder at the
supply end thereof and in proximity to the screw threads. The continued ignition
of the combustible mixture in cylinder 1 may be effected by an igniting device
maintained at a suitable temperature by the heat of combustion taking place in the
cylinder, as well understood."
It is not necessary that the ignition of the combustible mixture should take place
in cylinder 1; it might be effected in a separate chamber provided with an igniter
of the kind mentioned and inserted between the pipe 9 and the supply end of the
cylinder 1.
When very light hydrocarbon oils are used they can be supplied to the cylinder 7
by the branch 7, the heat developed by compression of the air in that cylinder
being sufficient to vaporise them, whilst the screw threads 5* in that cylinder will
effectually mix the vapour produced with the air. Or the oil may be previously
gasified by heat if desired. To obviate any possibility of flame travelling back
along the pipe 9 from the cylinder 1 to cylinder 7, diaphragms of wire gauze of
fine mesh can be introduced at the joints ab and c d. I however do not think
this will be necessary as the velocity of an explosive wave will be less than the
normal velocity of the gases in pipe 9, which is of comparatively small diameter.
The turbine in cylinder 7 is smaller than that in cylinder 1 and is so designed that it'
will compress air to a higher degree than the turbine in cylinder 1 would be able
to do, if it were used as an air compressor. This is rendered clear by the
development of one of the screw threads of each cylinder shown in the diagrams
Figs. 6 and 7.
Should it be desired to burn oils that are difficult to vaporise, the pump must be
designed to compress air to an even higher pressure than in the case where gas is
used, and the pump is to be used for the compression of air alone, and the air before
leaving the pipe 9 and entering the supply end of the cylinder 1, or a separate
explosion chamber as the case may be, is caused to first pass through an injector
nozzle 14 such as shown in vertical section in Fig. 8, so as to induce the heavy oil
to enter the chamber 15 by the pipe 16 and convert it into spray. which is then
introduced into the cylinder 1, or separate explosion chamber, as the case may be,
where it can be ignited as before. The same injecting device can also be used for
injecting a light oil or gas.
Water may be also supplied through the injector (Fig. 8), its conversion into
vapour serving to increase the volume of the gases in cylinder 1 and also to keep
this cylinder cooler than otherwise would be the case.
Perfect balance of end pressure may be obtained as in the case of the steam
engine Figs. 1 to 3 by duplicating the parts as shown diagrammatically in Fig. 9,
where there are two pumps each delivering into a pipe 9 connected with the supply
branch 2 of the engine, which is of the construction herein before described with
reference to Figs. 1 to 3.

page_text: 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. A rotary engine, applicable also as a pump, comprising a stationary cylinder
provided with an inlet and outlet for fluid, and one or two rotary turbines consisting
or each consisting of one or more screw threads that are of gradually increasing
pitch from end to end and carried by a shaft extending through the cylinder,
substantially as herein before described with reference to the drawings annexed.
2. My improved rotary steam or air engine, applicable also as a pump, constructed
substantially as hereinbefore described with reference to and shown in Figs. 1 to 3
inclusive of the drawings annexed.
3. A gas or hydrocarbon motor engine constructed substantially as hereinbefore
described with reference to and shown in Fig. 5, or Figs. and 8, or modified
Dated this 17th day of March 1896.
For the Applicant,
W. LLOYD WISE,
46 Lincoln's Inn Fields, Loudon, W.C., Chartered Patent Agent.