Improvements in or appertaining to Air Compressing Apparatus.
Year: 1894

page_text: Date of Application, 16th Mar., 1894
2008
PROVISIONAL SPECIFICATION.
Improvements in or appertaining to Air Compressing Apparatus.
We, JOHN SCARISBRICK WALKER, THOMAS ASCROFT WALKER and
EDWIN ROBERT WALKER all of Wigan in the County of Lancaster, Mechanical
Engineers, do hereby declare the nature of this invention to be as follows:-
In compressing air, it is desirable to avoid as far as practicable the act of
compressing in excess of what is required. So long as the air receivers, pipes,
etcetera, are filled with the compressed air and maintained at the required pressure,
anything beyond this is
power wasted.
Now this invention is designed so that, the instant the maximum required
pressure is reached, a relief valve shall be opened and all extra air shall
immediately pass out through the relief valve uncompressed, while, at the same
time, the stop valve of the engine or other governing apparatus shall simultaneously
be actuated so as to shut off steam from the engine and prevent racing. As close
to the compressing cylinder as possible, we place our new relief valve, and beyond
this in the supply pipe to the accumulator we arrange a back pressure valve.
From beyond this, we bring a small pipe to the regulating apparatus of the new air
relief valve. This regulating apparatus consists of the following parts: first, a
cylinder with a ram or piston therein weighted to the required pressure. A branch
pipe before alluded to enters this cylinder at the bottom. At the top of the
cylinder there is an escape open to the atmosphere, and in the middle of the
cylinder is an opening connected to the lower part of a second cylinder by a pipe,
and, if desirable, a regulating valve is fitted to this pipe. In this second cylinder
is a ram weighted through the medium of a compensating lever or other similar
weight having a piston rod, and upon this rod or connected therewith by any
suitable mechanism is the relief valve which can be of any suitable construction.
Connected also with the piston rod of either the first or second cylinder or both, is.
mechanism for shutting off steam from, or otherwise governing, the engine. -
The mode of action is as follows:-
The moment the maximum pressure is exceeded, the air passing through the
branch pipe raises the piston in the first cylinder. As the bottom of the piston
passes the central opening, the air rushes through the connecting pipe to the
second cylinder and thus raises its piston and opens the relief valve, the piston rod
of either cylinder being connected direct or by suitable link notion or gearing with
the throttle valve or other device governing the motive power engine. This piston
rising, the steam is slacked off from the engine and simultaneously the relief valve
is opened. The moment the maximum pressure is reduced below the amount for
which the first piston is weighted, this latter descends instantly. The central
orifice is now open to the atmosphere and the air from the bottom of the second
piston rushing back to it through the connecting pipe escapes at once to the air,
instantly closing the relief valve and opening the throttle valve or otherwise
inceasing the power of the engine. These relief valves and apparatus are useful in
almost any kind of apparatus in which safety valves are otherwise required or
where it is desirable to prevent the increase of pressure beyond a given amount.
It will be noticed that the main principle of this invention consists in using the
pressure of the air itself in the pipe leading to the accumulator to work a relay

page_text: which shall instantly effect the work instead of allowing the slight difference of
pressure to gradually work the effect, as it would do if the compressed air worked
the second cylinder direct, or if the first cylinder directly actuated the valve, and
that consequently any arrangement by which the compressed air is employed to
operate a relay of power and thus bring a sudden strong force to bear upon the
valve would form a part of our invention for it is quite immaterial whether the
compressed air itself be used to form the sudden lifting power that lifts the valve,
or the rising of the first piston brings another force into play such as for instance
a hydraulic device, an electric device or other relay of power. In some cases two
second cylinders with valves may be used.
Dated this 15th day of March 1894.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Patent Agents for the Applicants.
and
mprovements in or appertaining to Air Compressing Apparatus.
We, JOHN SCARISBRICK WALKER THOMAS ASCROFT WALKER
EDWIN ROBERT WALKER all of Wigan in the County of Lancaster, Mechanical
Engineers, 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 compressing air, gas or other fluid it is desirable to avoid as far as practicable
the act of compressing in excess of what is required. So long as the receivers,
pipes, etcetera, are filled with the compressed air or gas and maintained at the:
required pressure, anything beyond this
power wasted.
Now this invention is designed so that the instant the maximum required
pressure is reached a relief valve shall be opened and all air, gas or other fluid
then entering the compressing cylinder shall immediately pass out through the
relief valve uncompressed, while at the same time the throttle valve of the engine,
or other governing apparatus, shall simultaneously be actuated so as to shut off*
steam, gas or other motive power from the engine (where the compressor is driven
direct) and thus prevent racing.
This invention is equally applicable for compressors which are not driven
directly by steam or other engine (as for instance a strap driven compressor) in
which case the throttle valve or other governing apparatus may or may not be
dispensed with.
In the accompanying drawing:
Figure 1 is a front elevation of an air, gas or other fluid compressing apparatus
showing our invention;
Figure 2 a plan; and
Figures 3 and 4 sectional elevation and plan of a combined relief and retaining
valve.
In these figures, A is the compressing cylinder; B the throttle valve of the
engine for shutting off steam when such is used or other motive power from the
engine to prevent racing.
As close to the compressing cylinder as possible, we place a relief valve C, and
beyond this, in the supply pipe to the accumulator, we arrange a back pressure or
retaining valve D, or to economise space, we combine the relief with the back
pressure or retaining valve, as shown in Figures 3 and 4.
bring a small pipe E to the regulating apparatus for actuating the relief valve C.
From beyond this, we
This regulating apparatus consists of the following parts, first, a cylinder F with
a ram or piston therein weighted to the required pressure by the compensating

page_text: lever and weight Fl. A branch pipe E before alluded to enters this cylinder F
at the bottom. At the top of the cylinder there is an escape G open to the
atmosphere, and in the middle of the cylinder is an opening H connected to the
lower part of a second cylinder I by a pipe J and if desirable a regulating valve K
is fitted to this pipe. In this second cylinder is a ram having a piston rod M and
upon this rod or connected therewith by any suitable mechanism is the relief
valve C. To the upper end of the piston rcd M may be attached the lever d,
the outer end of which is so arranged that the lever F in its descent presses upon
it and so forcibly closes the relief valve should it by any chance stick or be
otherwise prevented from closing. Connected also directly or indirectly with the
piston rod M of either the second cylinder or the piston rod or ram of the first
cylinder or both, is mechanism for closing the governing valve B for shutting off
steam or other power or otherwise governing the engine, but as before stated this
mechanism is equally applicable for compressors driven indirectly as by a strap
and pulleys in which case this governing apparatus may or may not be dispensed
with.
The mode of action is as follows:-
The moment the maximum pressure is reached, the air passing through the
branch pipe E raises the piston in the first cylinder F. As the bottom of the
piston passes the central opening H, the air rushes through the connecting pipe J
to the second cylinder I and thus raises its piston and opens the relief valve C.
The piston rod of either cylinder I and F may be connected direct or by suitable
link motion or gearing with the throttle valve B or other device governing the
motive power engine, but when driven indirectly as when a number of compressors
are driven by the same engine or the compressor is a long distance from the
engine, this is dispensed with. This piston rising, the steam is slacked or shut off
from the engine and simultaneously the relief valve C is opened. We prefer the
steam or gas should be shut off entirely by the governing apparatus and to supply
the engine by means of a by-pass pipe and valve with sufficient steam to enable
it to run at any desired speed when not compressing. The moment the pressure
is reduced below the amount for which the piston F is weighted, this latter
descends instantly. The central orifice H is now open to the atmosphere through
the escape orifices G and the air or gas from the bottom of the second piston
rushing back to it through the connecting pipe J escapes at once, either into the
atmosphere or is conveyed away where desired. The relief valve C is instantly
closed, assisted if necessary by the falling of the lever F¹ upon the lever d and
opens the governing valve B or otherwise increases the power of the engine when
the compressor is driven direct. This relief valve C and its connections are
useful in almost any kind of apparatus in which safety valves are otherwise
required, or where it is desirable to prevent the increase of pressure beyond a
given amount.
It is desirable to reduce the waste space between the outlet valves and the
retaining valve to as small an amount as possible, and for this purpose we some-
times combine the relief valve C and retaining valve D in one casting, as shown in
Figures 3 and 4.
It will be noticed that the main principle of this invention consists in using the
pressure of the air or gas itself in the pipe leading to the accumulator to work a
relay which shall instantly effect the work, instead of allowing the slight difference
of pressure to gradually work the effect, as it would do if the compressed air or
gas worked the second cylinder direct or if the first cylinder directly actuited the
valve, and that consequently any arrangement by which the compressed air or gas
is employed to operate a relay of power, and thus bring a sudden strong force to
bear upon the valve, would form a part of our invention, for it is quite inmaterial
whether the compressed air or gas itself be used to form the sudden lifting power
that lifts the valve, or the rising of the first piston brings another force into play
such as for instance a hydraulic device, an electric device or other relay of power.
In some cases two second cylinders with valves may be used.

page_text: Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
1. The improvements in or appertaining to air, gas or other fluid compressors
substantially as described, whereby when the maximum required pressure is
reached a relief valve is opened and all air, gas, or other fluid then entering the
compressing cylinder passes out through the said valve uncompressed, while at
the same time the throttle valve or governing apparatus of the engine is
simultaneously actuated to regulate the speed and prevent racing.
2. The use in combination with air, gas or other fluid compressors, of a relief
valve such as C, and a regulating apparatus, the latter so arranged that it will
open the relief valve when the maximum required pressure in the accumulator is
attained whereby the act of compressing beyond what is required is avoided
substantially as described.
3. In compressors, the special arrangement or construction of the combined
relief and retaining or back pressure valve, substantially as and for the purpose
described.
4. The general arrangement and construction of parts forming our improved air,
gas, or other fluid compressing apparatus substantially as herein set forth.
Dated this 15th day of January 1895.
WM. P. THOMPSON & Co.,
Of Liverpool, Manchester, Birmingham, and London, Patent Agents.