Improvements in Electro Motors and Dynamos for use in Mines and other places.
Year: 1891

page_text: Date of Application, 31st Jan., 1891
..Complete Specification. Left, 2nd Nov.,..1891-Accepted, 5th. Dec.,. 1891
PROVISIONAL SPECIFICATION.
"Improvements in Electro Motors and Dynamos for use in Mines
and other places.
WILSON HARTNELL Engineer Volt Works, Leeds, do hereby declare,the nature
of this invention to be as follows:-
My improvement consists in encasing the dynamo, on motor-in-a-wrought iron.or
cast iron-box which may be cylindrical rectangular or any convenient shape,
approximately air tight and arranging the dynamo. or motor so that the iron case
forms the return magnetic circuit.
The arrangement I prefer for motors for coal. cutting machines such as that
known as the Gillott type is to place the exciting coils in line with each other &
immediately behind the pole pieces.
The iron case is made strong enough to resist the explosion of .coal-gas.& air at
atmospheric pressure.
In sometimes place all the necessary resistances, switches.& cut outs within the
iron box. The advantage of 'the above arrangement is that the dynamo or motor
maybe placed in close contact with the frame of the machine to be driven or
surrounded in any way by its parts so as to occupy.a. minimum of space-without in
any way disturbing the magnetic circuit. It also saves the weight of a case applied
to an ordinary dynamo. The dust is entirely excluded from the working parts.
If explosive gases penetrate into the interior of the dynamo and are there-lighted
by sparks on the commutator, the switches or other accessories, the case being
strong to resist the pressure of the explosion and no flame can escape.externally.
In some cases lefurther make a small opening into the box which may be tubular
ofmoderate length.and fill it with wire gauze-or..its equivalent through which the
expanding gases can escape without any flame passing.
In places especially hazardous from inflammable vapours I. provide a small
chamber with inlet. from outside; & passage to the interior and two taps in which
I-place from time to time carbonate of, lime and acid or other suitable.chemicals
which give off non-inflammable gas and thus render the air inside,the dynamo,or
motor case incapable of supporting combustion.
I prefer to combine the itaps so that one passage must be shut..before the other
is opened. When it is impossible to arrange the motor with the magnetic.circuit
wholly within the case I still provide.an airtight case.capable of resisting internal
explosion or the escape of flame and apply. when desirable the wire gauze-escape
passage or the arrangement for rendering the imprisoned air incapable of supporting
combustion.
This motor is especially useful in coal mines for driving.coal cutting machines,
for pumping water, for hauling, &c. or for any other place where much dust, or
prejudicial vapours. are present.
cool T
WILSON HARTNELL.
COMPLETE SPECIFICATION.
1.Improvements.in, Electro Motors.and Dynamos for use in: Mines
and other places.
I, WILSON HARTNELL, Engineer, Volt Works, Leeds, do hereby declare.rthe
nature of this invention and in what manner 'the same is to be performed, ito.<be
particularly described and ascertained in and by the following statement :-
My improvements consist in encasing the motor or dynamo in a wrought iron or
D027

page_text: cast iron box which may be cylindrical, rectangular or any convenient shape,
approximately air tight, and arranging the motor or dynamo so that the iron case
forms the return magnetic circuit.
In order to fully describe my invention I have annexed two sheets of drawings,
on which
Fig. 1 is a section, taken transversely across the armature axis, of a motor
arranged after my plan, whilst
Fig. 2 is a corresponding view showing such parts as are essential to a proper
understanding of the matter.
Fig. 3 shows an end view of the peep and hand hole cover-for gaining rapid
access to the commutator brushes etc.; and
Fig. 4 is a section through a tap for generating non-inflammable gases.
To these figures further reference will be made.
Figs. 5 and 6, which are transverse and longitudinal sections, respectively, show
now a motor, or dynamo, may be arranged, in a cast iron case, with one exciting
coil, withdrawable by unfastening the lid X, X; the main body of, the casting
being in one piece.
Figs. 7 and 8 show an arrangement in cast iron, with two exciting coils removable
by the lids Y Y, and Y Y
Figs. 9 and 10 represent an arrangement for wrought iron or steel, with one
exciting coil, with the case divisible at the joint Z, Z.
In Figs. 6 and 8 the side covers for the with Irawal of the armatures, which may
be arranged as in Figs. 2 and 3, are not shown. Bolts, screws, and rivets-not
shown must be used, as most convenient, for uniting the parts of the cases. The
same letters, as far as they are required, represent the same parts in all the figures.
The arrows show the direction of the return magnetic circuit, supposing the
pole B to represent the north.
The arrangement I prefer for motors for coal cutting machines-such, for
example, as that known as the Gillott type is to place the exciting coils A, A,
in line with each other and immediately behind the pole pieces B', B2, as shown
in Fig. 1, etc.
The iron case C, C, is made strong enough to resist the explosion of coal gas
and air at atmospheric pressure and is here arranged to form the return magnetic
circuit as shown by the arrows. In all cases I prefer to place all the necessary
resistances, switches, and cut outs, such as may get red hot, or spark, within the
iron box.
The advantage of the above arrangement is that the motor or dynamo may be
placed in close contact with the frame of the machine to be driven, or surrounded
in any way by its parts, so as to occupy a minimum of space, without in any way
disturbing the magnetic circuit. It also saves the weight of a case applied to an
ordinary motor or dynamo-an important matter in mines where motors have to
be moved about in cramped spaces..
―
Fig. 1 shows how a quadrant switch-mounted on the spindle D-may be
arranged to bridge across a series of my bush terminals for a shunt wound motor.
The current first passes from the positive terminal P to the quadrant-which when
switched off occupies the position shown in dotted lines-and this when moved
gradually across brings about the following results: When the second terminal is
reached a current is sent to the shunt coils which magnetises the frame to its full
extent and it also passes through suitable resistances to the commutator brushes
and starts the motor; when the third terminal is bridged the current passes by a
part of the resistance, and the motor is made to run nearly to its full speed, and on
the fourth terminal being reached all resistances are cut out and the full current is
on. The end of the shunt coil is also connected to the first terminal, through a
high resistance between the first and second terminals, for the shunt coils to
discharge through harmlessly on switching off.
The shaft of the quadrant-switch shown rotates in a stuffing box, a similar box
being required when a push and pull switch is arranged. The negative current
i

page_text: after leaving the commutator brush may be led through a cut-out, as at E, and
thence to the negative terminal N, thus all accessories are arranged inside the
airtight magnetic case. These details may of course be varied as circumstances
demand. The bearings of the armature shaft are oiled from the outside as shown.
A
Any convenient portion of the airtight magnetic casing may be made to remove
in order to effect repairs or give attention to the brushes. A handy mode of
getting at these latter is shown in Figs. 2 and 3 where F and F' are two strong
glass peep-holes mounted in a frame G, shown in front view in Fig. 3. This frame
may be swung out of the way leaving the hand-holes open, and on being pushed
back it locks itself in and under the under cut portions H' of the cover H.
mode of regulating the position of the armature brushes from the outside is shown
in Fig. 1 where J is a rod with a swivel joint passed through a screwed bush.
The arrangement of the armature shaft and its stuffing box and bearings are
clearly shown in Fig. 2 to remove the armature the cover H requires taking off.
The dust is entirely excluded from the working parts. If explosive gases
penetrate into the interior of the dynamos and are there lighted by sparks on the
commutator, the switches or other accessories-the case being strong enough to
resist the pressure of the explosion-no flame can very well escape externally.
In some cases however I further make a small opening into the box which may
be tubular of moderate length and fill it with wire gauze, or its equivalent, through
which cooling materials the expanding gases can escape without any flame passing,
as shown at K in Fig. 2.
In places especially hazardous from inflammable vapours I provide a small
chamber with inlet from outside and passage to the interior and two taps, or their
equivalent, in which I place from time to time carbonate of lime and acid, or other
suitable chemicals, which give off non-inflammable gas, and thus render the air
inside the dynamo or motor case incapable of supporting combustion. I prefer to
combine the taps so that one passage must be shut before the other is opened.
A simple plan of arranging for the introduction of chemicals for producing gas
is the following make the tap large enough to contain the chemicals in its
horizontal barrel L, see Figs. 1, 2 and 4. An opening, shown clear in Fig. 1,
permits their introduction, after which the barrel is turned partly round and this
opening closed. This movement opens up a small outlet for gas, M, see Fig. 4,
previously closed, by which the generated gas now passes into the channel Nand
so into the interior of the case. By turning the barrel still further round a lower
opening allows the chemicals to be emptied out, and this without removing any
part of the appliance. In Fig. 10 a modified arrangement of this appliance is
shown fitted into a recess in the side of the case so as to be out of harms way.
Where it is inexpedient to arrange the motor with the magnetic circuit wholly
within the case I still provide an air tight case capable of resisting internal
explosion and preventing the escape of flame, and I apply when desirable the wire
gauze escape passage, or the arrangement for rendering the imprisoned air incapable
of supporting combustion.
This motor is especially useful in coal mines for driving coal cutting machines,
for pumping water, for hauling, etc., or for any other place where much dust or
prejudicial vapours are present.
All mountings may be fitted in recesses in the ends or sides of the case,
when the height has to be restricted, in order to leave no projections liable
to be damaged in a mine. All handles may be made removable for the same
reason.
It will of course be understood that when I introduce non-inflammable gas, no
relief and cooling tube K is fixed.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-

page_text: ito withstand an explosion in-ther.interior the said case forms the .return.magnetic
circuit, substantially as herein described.
2. The mode of encasing an electro-motor or dynamo as in Claim 1, with all
switches, resistances, cut-outs, and the like, in. the interior, substantially as herein
.described.
3. The use of a relief and cooling tube applied to the case of an electro-motor.or
dynamo in order to render internal explosions. harmless, substantially as .described
herein and shown at K in Fig. 2.
4. The mode and apparatus for introducing non-inflammable gases. into..the
interior of an encased electro-motor or dynamo, substantially as described herein.
5. The encased electro-motor or dynamo. arranged, constructed, tand operated,
substantially as described herein, and shown in Figs. 1rand..2.
6. The arrangements of encased electro-motors or dynamos. as.described.. herein
and shown in Figs. 5 and 6; 7 and 8 and 9 and 10.
7. The arrangement of the end-cover, with hand and peep-holes, substantially as
described herein and shown in Figs. 2 and 3, applied to.encased. electro-motors.or
dynamos
8. The arrangement of brush-regulator substantially.as.described and shown.in
Fig. 1applied to encased electro-motors or dynamos.
Dated this 31st day of October 1891.
WM. SNOWDON,
9; Old Bank Chambers, Leeds, Yorks., Agent for the Applicant.