Improvements in Compressed Air Motors.
Year: 1890

page_text: Date of Application, 3rd Jan., 1890
Complete Specification Left, 3rd Oct., 1890-Accepted, 8th Nov., 1890
PROVISIONAL SPECIFICATION.
Improvements in Compressed Air Motors.
A communication from abroad by Doctor RUDOLF PROELL, of Dresden, Saxony,
German Empire, Civil Engineer, and the firm of O. L. KUMMER AND COMPANY,
of the same place, Machine Makers.
I, JOHN CLAYTON MEWBURN of 55 and 56 Chancery Lane in the County of
Middlesex Fellow of the Institute of Patent Agents, do hereby declare the nature of
this invention to be as follows:-
:-
In a system of compressed air for working motors in towns or districts, small
motors can only work advantageously if the air besides working under full pressure,
also works with expansion. The decrease in temperature in such working, however,
requires a heating of the air before it enters the motor or an increase in, or trans-
mission of, temperature during expansion, which increase of temperature will remove
the difficulties created by cold in the passages of the motor and at the exhaust.
In the compressed air motor which forms the subject of this invention there is at
its lowest point, that is to say underneath the larger cylinder, in which cylinder the
decrease in temperature mainly takes place, a source of heat, which may consist either
of a gas jet or of the flame of liquid fuel, into which gas or fuel air at atmospheric
or higher pressure is introduced for the increase of their heating power.
The bottom of the larger cylinder inay be recessed or indented or be formed with
straight or circular ribs to enter into corresponding recesses in the body of the piston,
in order to : preass the transmission of heat to the air, which in the large cylinder
works mainly by expansion. Around the heating part an annular channel is provided
through which the compressed air passes before entering the upper smaller cylinder.
In passing through this channel the air takes up a certain quantity of heat, and this
allows of the air working in the small cylinder by expansion by being shut off early,
after which the air from the small cylinder passes into the large cylinder for working
by further expansion.
The governor actuates a regulating valve through which the compressed air has
to pass before entering the small cylinder and thus the governor regulates the speed
of the engine. Again the governor may also actuate a regulating valve in the gas
supply pipe or in the pipe for the liquid fuel as the case may be. If compressed air
is admitted to the flame this air may be allowed to issue from the slide valve box
and be regulated by a valve or cock which can be more or less throttled as found
desirable. The regulation of the compressed air through the regulating valve that
the governor actuates also regulates the tension or pressure of the heating air, so that
by this device the heating effect will decrease if the motor developes less power and
vice versa.
Dated this 3rd day of Janmar 1800
COMPLETE SPECIFICATION.
Improvements in Compressed Air Motors.
A communication from abroad by Dr. RUDOLF PROELL, of Dresden, Saxony, German
Empire, Civil Engineer, and the firm of O. L. KUMMER AND COMPANY, of the
same place, Machine Makers.
.
1, JOHN CLAYTON MEWBURN of 55 & 56 Chancery Lane in the County of Middlesex
Fellow of the Institute of Patent Agents do hereby declare the nature of this inven-
tion and in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:-
When compressed air is the fluid which drives or actuates á motor the dynamic
Prine 81

page_text: power of the fluid, as is well known, can be used to the best advantage only if it works
by expansion as well as by full pressure. If, however, compressed air of atmospheric
temperature is expanded, more or less intense cold is created which may in the
almost unavoidable presence of water or water vapour lead to the formation of ice
in the passages of the motor, and to other undesirable consequences.
The present invention is intended to overcome these difficulties, and it mainly
consists in the combination with a high pressure cylinder and a low pressure cylinder
of a flame or source of heat whereby the low pressure cylinder is heated and
the compressed air is thus enabled to work expansively, without undue reduction of
temperature.
The construction which is considered most suitable for the application of the inven-
tion is shown in the annexed drawings in which Figure 1 represents a sectional
elevation and Figure 2 a cross section of the motor. A is the high pressure cylinder
and B the low pressure cylinder, these two cylinders being preferably placed in the
relative positions shown; the two pistons are single acting and are connected by a
common trunk or piston rod, within which a sliding block moves in a horizontal
slot and actuates the crank. An eccentric crank Z actuates a slide valve in a similar
manner and this slide valve is so constructed that the compressed air coming through
the throttle valve V is first admitted to the high pressure cylinder A, then into the
low pressure cylinder B, and then passes to the exhaust. Although this is the
preferred construction it is evident that the invention can be applied to a motor in
which the different parts have any other suitable positions and arrangement.
The low pressure cylinder is subjected to the heating action of a suitable source of
heat, preferably a gas jet H. In order to absorb the heat and to give it off more
readily to the expanding compressed air within the low pressure cylinder, the latter
may be provided outside and also inside the cylinder cover or bottom with suitable
ribs or indentations and the bottom of the piston may have corresponding ribs or
indentations. In this manner the air is heated during the period of expansion so as
to prevent undue reduction of temperature.
.
In or near the heated parts of the low pressure cylinder one or more channels a of
an annular or other suitable section may be provided, which in the construction
shewn begin at the flange F1 and end at the flange F2. The compressed air may
pass through the said channels before entering the high pressure cylinder, so as to
take up a certain amount of heat which will enable it to work with some expansion
in the high pressure cylinder. The compressed air is conducted to the high pressure
cylinder through the pipe P or other suitable conduit, in which conduit is the throttle
valve V, after passing through which throttle valve the compressed air enters the
motor in the manner already described. A governor R actuates the throttle valve V
by means of suitable connections d, and thus regulates the supply of compressed air to
the motor; the governor is further connected with the cock or any other suitable
device which regulates the quantity of heat supplied to the low pressure cylinder.
The simultaneous control of the supply of compressed air and heat by means of one
governor is of importance because if for instance the motor is only driving a light
load, then less compressed air is admitted to the motor, and therefore less heat is
required by the expanding air in the low pressure cylinder; if therefore the latter
were subjected to a constant source of heat it might become overheated and
vice-versa.
Having now particularly described and ascertained the nature of the said inven-
tion as communicated to me and in what manner the same is to be performed
I declare that what I claim is :-
1. In a motor actuated by compressed air the combination with a high pressure
cylinder and a low pressure cylinder, of a flame or source of heat whereby the low
pressure cylinder is heated and the compressed air therefore enabled to work
expansively, without undue reduction of temperature substantially as hereinbefore
described.
2. In a motor actuated by compressed air, the combination with a high pressure

page_text: cylinder, a low pressure cylinder and a flame or source of heat as referred to in
claim 1, of one or more channels in or near the heated part of the low pressure
cylinder, through which channels the compressed air passes so as to become heated
before entering the high pressure cylinder, and is thereby enabled to work expansively
in the high pressure cylinder substantially as hereinbefore described.
3. In a motor actuated by compressed air, the combination with a high pressure
cylinder, a low pressure cylinder, and a flame or source of heat as referred to in
claim 1, and with or without the air heating channels referred to in claim 2, of a
governor which simultaneously regulates the admission of compressed air to the high
pressure cylinder, and the amount of heat acting on the low pressure cylinder
substantially as hereinbefore described.
4. Constructing compressed air motors as hereinbefore described and represented
in the accompanying drawings.
J. C. MEWBURN.