Improvements in Combined Gas Motors and Compressors or Blowers.
Year: 1899

page_text: PROVISIONAL SPECIFICATION.
Improvements in Combined Gas Motors and Compressors or Blowers.
We, WILLIAM JOHN CROSSLEY, of Crossley Brothers, Limited, Openshaw, Man-
chester, and JAMES ATKINSON, of The Woodlands, Marple, Engineers, do hereby
declare the nature of this invention to be as follows:-
This invention relates to combined gas motors and compressors or blowers in
which the pistons of the compressing cylinders are directly driven by the pistons
of the gas motor cylinders or at any rate so driven as to complete their strokes
together.
A specially suitable application of this invention is to blowing engines for
compressing the air used for blast in a blast furnace and driven by the gas from
the furnace itself. Such gas has a very low thermal value and it is of importance
that the residual burnt gases left in the combustion chamber of the motor
cylinder at the termination of an exhaust stroke should be scavenged out and
replaced by pure air. The object of this invention is to take this scavenging air
from the compressing cylinder at the termination of its delivery stroke, utilizing
mainly the air left in this cylinder in its clearance spaces so as not to materially
reduce the volume of air delivered by the cylinder.
A suitably sized pipe communicates from the compressing cylinder to the
combustion chamber of the motor cylinder having a valve at each end. The
valve at the compressing cylinder is normally closed by a spring strong enough
to prevent the compression pressure opening the valve but it is opened by the
piston pushing it open at the extreme end of its compressing stroke. The valve
on the motor cylinder opens to the combustion chamber automatically against
an adjustable spring.
Assuming that an exhaust stroke is just about being completed in the motor
cylinder the corresponding compressor piston is just completing a delivery stroke
in the compressing cylinder and its clearance spaces are filled with air at, say,
10lbs. pressure per square inch above the atmosphere. The compressing cylinder
piston taps open the valve on the connecting pipe and admits air at 10lbs. pressure
into it. This 10lbs. pressure opens the automatic valve and allows air to rush
into the combustion chamber of the motor cylinder. The exhaust valve of the
motor cylinder being also kept open at this time. the inlet of the scavenging air
being suitably placed in relation to the position of the exhaust valve, the scaveng-
ing air drives out any burnt gases and replaces them with fresh air.
The extent to which the valve on the compressing cylinder can be opened by
the piston and the volume of the clearance spaces taken in combination with the
strength of the spring on the automatic valve limits the amount of air passed into
the motor cylinder at each scavenging operation and prevents waste.
Should the motor cylinder operate on the "Otto or four stroke cycle and the
compressing cylinder deliver compressed air at each revolution, no scavenging air
will pass into the motor cylinder excepting after exhaust strokes as at the alternate

page_text: intervals there will be pressure in the motor cylinder which prevents the passage
of any air.
Dated this 8th day of December 1899.
W. J. CROSSLEY.
JAMES ATKINSON.
Improvements in Combined Gas Motors and Compressors or Blowers.
We, WILLIAM JOHN CROSSLEY, of Crossley Brothers, Ltd., Openshaw, Man-
chester, and JAMES ATKINSON, of The. Woodlands, Marple, Engineers, do hereby
declare the nature of this invention and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement:
This invention relates to combined gas motors and compressors or blowers, in
which the pistons of the compressing cylinders are directly driven by the pistons
of the gas motor cylinders, or, at any rate, so driven as to complete their strokes
together.
A specially suitable application of this invention is to blowing engines, for
compressing the air used for blast in a blast furnace and driven by the gas from
the furnace itself. Such gas has a very low thermal value, and it is of importance
that the residual burnt gases left in the combustion chamber of the motor
cylinder at the termination of an exhaust stroke should be scavenged out and
replaced by pure air.
The object of this invention is to take scavenging air from the compressing
cylinder utilising mainly the air left in this cylinder in its clearance spaces, so as
not to materially reduce the volume of air delivered by the compressor.
Our invention consists in a method of scavenging in a combined gas motor and
air compressor, in which a volume of air is conveyed from the compressor to the
motor cylinder by means of a pipe, provided with valves, one at each end, which
are automatically closed, except at the termination of an exhaust stroke, when
they open to permit the passage of air for scavenging the motor cylinder.
In carrying our invention into effect, we provide a combined gas engine and air
compressor, having the air compressing piston driven directly by the piston of
the gas motor; having also the combustion chamber of the motor in communica-
tion with the compressing cylinder, at certain periods, by means of a pipe, provided
with automatically worked valves.
In order that our invention may be more clearly understood we will describe it
more particularly, and will refer to the accompanying two sheets of drawings in
which, Figure 1 is a plan of a combined gas engine and air compressor. The
gas and air admission valves and the mechanism for controlling the same are not
shewn.
Figure 2 is a sectional elevation of the same taken through the lines a, x, x,
of Figure 3.
Figure 3 is a sectional end view taken through y, y, of Figure 2 but with the
piston removed.
Figure 4 is a section through the scavenging pipe and spring operated valves,
shewing the valves open to allow the scavenging air to pass from the cylinder
of the air compressor to the combustion chamber of the gas motor.
Figure 5 is a vertical section through the spring operated valve which leads
to the combustion chamber.
Figure 6 is a vertical section through the spring operated valve which leads from
the air compressor.

page_text: Supported on a suitable base a Figure 2, we secure an outside cylinder b, prefer-
ably made in two pieces, c and d bolted together. One of these pieces c, is pro-
vided with the usual connections for air and gas admission and exhaust valves,
and has cast within it, strengthened by webs y an internal cup-shaped portione,
arranged so that one side of it forms, together with an inner pressure cylinder f,
a combustion chamber h while the other side forms part of a space k which extends
all round the cylinder f, forming a water jacket.
A single acting air compressing cylinder 7 of greater internal diameter than
the inside of cylinder f, but concentric with the same, is bolted to the portion d,
of the cylinder b, having air suction and discharge valve boxes m, m, and o, o,
respectively, as shewn in section at Figure 3, with valves (not shewn) arranged in
any well understood manner.
Bolted to the compressing cylinder 7 is a bed plate n, with bearing blocks p, p,
for supporting a crankshaft r, having fly wheels s, s, keyed to it, one on each
end.
Sliding freely within the cylinder f, Figures 2, and 4 is a motor piston t,
provided towards one end with packing rings g, and having at the other end an
enlargement u, also provided with packing rings g, thus forming a piston for
the air compressing cylinder in one piece with the piston t.
Bosses 27 are provided inside the piston to form supports for a connecting
rod pin.
Motion is imparted to the fly-wheels s, s, by means of a connecting rod with
connections to the crankshaft r, and piston t, in any well understood manner.
In order that the waste gases may be expelled from the clearance spaces of the
cylinder, and replaced by pure air at the completion of the exhaust stroke, we
provide a pipe Figures 1, 2, 3 and 4 one end of which is bolted to a valve
chest 1 Figure 4, containing a spring controlled valve 2, and suitably secured to
the air compressing cylinder 7, while the other end of the pipe is bolted to
a valve chest 3, containing a spring controlled valve 4. This valve chest is
inserted in so as to closely fit a neck piece y¹ in the portion e of the cylinder b,
leading into the combustion chamber h; it may be secured to the cylinder by
any suitable means.
Referring to Figure 6 the valve 2 normally kept closed against the pressure of
the air in the compressor by a spring 5, and provided with a long hollow tail
piece 6, guides the valve 2 when it is opening, by sliding in the bored projection S
cast on the cover 9. A spindle 11 screwed at both ends is passed into the tail
piece 6 and screwed into a threaded portion 7 of the valve 2, till it projects enough
to give the desired valve lift. The valve 2 is opened against the pressure of the
spring 5, by the piston u coming in contact with the spindle 11 which projects
beyond the screwed portion 7 of the valve 2 thus allowing the compressed air to
pass into the valve chest 1, and thence into the pipe . The other end 12 of
the spindle 11 has two nuts 13, 13, to keep it from slackening; it is moreover
protected by a screwed dome 23, which also prevents any escape of air from
the valve chest 1.
The valve 4 (Figure 5) has a long spindle 14, screwed at its end 15, and guided
by a bored bracket 16, projecting from the inside of the valve chest 3 and also
acting as a support for a light spring 17. This spring 17, acting on a collar 18,
provided with a ferrule 19, which presses against a washer 21, and nuts 22, 22,
on the end 15 of the spindle 14 provides means by which the amount of air to
be used for scavenging can be regulated at will.
A cover 24 with a dome 25 screwed to it for preventing escape of air, and
protecting the spindle end 15 is bolted to the valve chest 3.
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The motor hereinbefore described works on the ordinary Otto or four stroke
cycle; the same method of scavenging that we adopt for the Oito cycle, can,
however, be readily employed in any motor receiving an impulse every revolution
provided the pistons complete their strokes together.
Assuming that an exhaust stroke is just about being completed in the motor

page_text: cylinder by the piston t, the corresponding compressor piston u is just com-
pleting a delivery stroke in the compressing cylinder whose clearance spaces are
filled with air at, say 10lbs. pressure per square inch above the atmosphere. The
compressor piston comes in contact with the end of the spindle 11 which projects
through the valve 2, and opens it against the pressure of the spring 5, thus
admitting air at 10lbs. pressure into the valve chest 1, and the pipe . This air
at 10lbs. pressure enters the valve chest 3 and opens the automatic valve 4 against
the resistance of spring 17, and allows air to rush into the combustion chamber h
of the motor cylinder f. The exhaust valve 26 (shewn in dotted lines in Figure 1)
for the motor cylinder f being also kept open at this time, and the inlet of the
scavenging air being suitably placed in relation to the position of the exhaust
valve 26, scavenging air drives out the burnt gases and replaces them with fresh
air.
The extent to which the valve 2 on the compressing cylinder 7, can be opened
by the piston and the volume of the clearance spaces, taken in combination
with the strength of the spring 17, on the automatic valve 4 limit the amount of
air passed into the combustion chamber at each scavenging operation, and
prevent waste.
It will be observed that the compressing cylinder 7 delivers air through the
delivery valve boxes o, o, at each revolution. No scavenging air will, however,
pass into the combustion chamber h, except after exhaust strokes as at the
alternate intervals there will be pressure in the motor cylinder f which keeps the
valve 4 closed, so preventing the passage of air.
We do not bind ourselves to the use of the particular forms and constructions
of valves and pipes described herein before as it is obvious that we may vary
them considerably, to suit different circumstances, without departing from our
invention.
In carrying our invention into effect, we do not materially increase the clearance
spaces, but keep them practically the same as is necessary when no scavenging
arrangement is adopted; moreover the connection between the motor cylinder and
air compressor is kept closed, except during the short time necessary for allowing
sufficient scavenging air to pass into the motor cylinder.
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. In a combined gas motor and air compressor the pistons of which complete
their strokes together, the method of scavenging the motor cylinder consisting in
admitting compressed air from the cylinder to the back of the motor piston, with-
out materially diminishing the volume of air delivered through the main delivery
valves, substantially as described.
2. An apparatus for carrying out the method of scavenging the motor cylinders
claimed in Claim 1, in which a spring controlled valve automatically opens as
the piston of the compressor completes its stroke, and allows compressed air to flow
along a pipe through a second spring controlled valve into the motor cylinder
expelling the burnt gases and filling the said cylinder with pure air substantially
as described.
3. In a combined gas motor and air compressor the construction and arrange-
ment of valve and communication between the compressor and motor power
cylinders, substantially as described and illustrated in the accompanying drawings.
Dated this 6th day of September 1900
MARKS & CLERK,
18, Southampton Buildings, London, W.C.,
13, Temple Street, Birmingham, and
25, Cross Street, Manchester, Agents.