Improvements in Dynamo-electric Machines.
Year: 1892

page_text: Date of Application, 25th July, 1892-Accepted, 27th Aug., 1892
COMPLETE SPECIFICATION.
Improvements in Dynamo-electric Machines.
I, FREDERIK VILHELM ANDERSEN, Electrical Engineer, of 14 Westdown
Road, Catford Bridge, in the County of Kent, 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 :-
This invention for improvements in dynamo-electric machines has for its object
to design the machine in such manner that the cost of construction shall be con-
siderably reduced, the field magnet coil and working parts shall be completely
closed in, in an improved manner, the magnetic circuit shall be principally of flat
wrought iron plates, and the brushes shall be automatically and efficiently adjusted
for wear.
In the accompanying three sheets of illustrative drawings
Figure 1 is a vertical longitudinal section of an electric motor constructed according
to this invention.
Figure 2 is an end elevation of the same.
Figure 3 is a cross section of a box in which a main bearing is fixed and which
carries the brushes.
Figures 4, 5, and 6 are detail views showing the method of supporting the
brushes.
The main frame of the motor is constructed of one casting of iron symmetrically
arranged with respect to a central plane perpendicular to the axis, and also a
vertical plane through the axis, and consists of the bed plate a vertical end
standards and top plate and pole piece c.
The other pole piece d is formed in the top of the core e which is built up of
and
flat wrought iron plates secured together by two flat wrought iron bars ap
also by a bolt ar and is seated in a recess in the bed plate a and secured thereto by
the screws f. In small machines the core e is of round wrought iron and fits into a
circular recess in the bed plate. The core is in this case fitted with a cast iron
pole piece taking the place of d in Figure 2. The pole picces and standards are
bored in place at one setting to receive respectively the armature and the boxes
in which the bearings for the armature shaft are fixed. It will be seen that the
parts of the main frame are bored at one setting and will be thus perfectly true
with one another, the holes in the standards & for the boxes being the same
diameter as the bore of the pole pieces for the armature so as to allow of the ready
insertion and withdrawal of the armature A.
There is only one exciting coil h for the magnets. This coil is placed on the
core e and inserted with this core sideways between the two end standards b. The
sides are then closed up by flat wrought iron plates secured by screws l.
The magnetic circuit is thus formed almost entirely of wrought iron and the cost of
construction is considerably reduced by using flat plates only.
The cast iron boxes y are turned to fit the holes in the standards 6 and are
secured in place by means of the screwed studs and nuts m, the studs passing
through slots n in the box at the commutator end to allow of the lead or position of
the brushes being adjusted.
The cast iron boxes y are bored to receive the bearings o which are driven
into place and secured by small set-screws p. The automatic lubrication of the
I large
bearings is effected as follows:-In each box g is a circumferential hole
enough to allow of the insertion of a ring r. The ring is inserted before the
The holes
armature shafts is in place and takes into a recess in the bearing o.
are provided with covers and the boxes 9 are provided with draw off cocks .
The lubricant is filled into the boxes y and the rings r bearing on the shaft s dip in

page_text: the lubricant and are rotated by the shaft s and lubricate it. The lubricant can be
drawn off by the cocks r.
Each brush aa is secured by means of a thumb screw ac in its holder ab
fixed by means of screws ad to the insulating plate ae secured by means of
bolts ag, and back plate ah and lock nuts ai to a radial web af of the
box g, the box at the commutator end of the motor being constructed sufficiently
long to receive the commutator between the bearing o and the end standard .
The bolts ay pass through slotted holes al in the web af so that the plate ae
has a limited radial motion. The brush is forced on to the commutator by a
spring am fixed. to the web af and to a bolt un fixed to the sliding plate ae
and passing through a slotted hole in the web af. The brushes are thus auto-
matically forced against the commutator in a radial direction as they wear. By
this arrangement the end of the brush which bears on the commutator will
retain its original shape unaffected by wear. The brushes aa are enclosed by
a brass tube do fitting on the box g.
The small brushes as shown in Figure 6 may
be used on one side of the commutator and one large one as shown in Figure 5 on
the other so as to take away the ridge formed on the commutator between the
other two brushes. The armature A is a drum armature, the coils for small
machines being wound in grooves in the core.
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 1
claim is :-
1. The construction and arrangement of the main frame of an electric motor
substantially as described and for the purposes set forth.
2. The construction and arrangement of the main frame of an electric motor
whereby the pole pieces and the seats for the bearing are bored at one setting
substantially as described and for the purposes set forth.
3. The construction and arrangement of the magnetic circuit of an electric motor
almost completely of flat wrought iron plates substantially as described and for the
purpose set forth.
4. In an electric motor the special arrangement as shown and described with
reference to the drawings whereby a single coil is employed to excite the two
poles.
5. The construction and arrangement of the bearings for the armature shaft
consisting of a bush inserted centrally into an oil box substantially as described.
6. The construction and arrangement of the brush gear whereby the brushes are
automatically forced against the commutator in a radial direction as they wear
substantially as described.
7. Mounting the brush gear on a frame adjustably secured to the main frame of
the motor and enclosing it by a tube surrounding the said frame, the whole sub-
stantially as described.
8. The construction and arrangement of an electric motor substantially as
described with reference to the drawings.
Dated this 25th day of Lul. 1000
WHEATLEY & MACKENZIE,
40, Chancery Lane, London, Agents.