Year: 1898

page_text: Date of Application, 30th Aug., 1898
Complete Specification Left, 29th May, 1899-Accepted, 22nd July, 1899
:-
I, REGINALD BELFIELD, of 32, Victoria Street, in the City of Westminster,
Electrician, do hereby declare the nature of this invention to be as follows:-
My invention relates to induction motors such as are usually operated by two
or more currents differing in phase.
With motors of this description an additional resistance is generally required
in the secondary circuit and this has been provided for by permanently connec-
ing the ends of the conductor bars forming such secondary circuit through rings
or plates of comparatively high resistance."
According to my invention I provide these rings or plates with radial blades
which when the secondary member is rotated produce air currents and thereby
ventilate the same; furthermore I prevent said rings from being separated from
the bars owing to unequal expansion of the metals when the temperature changes
by connecting the parts together with bolts and nuts having spring washers.
In the accompanying drawings, Figure 1 is an end elevation of a motor cou-
structed in accordance with my invention, the end plates or covers being removed.
Figure 2 is a detail sectional view of a portion of the machine shewn in
Figure 1, portions of the end covers being also shewn.
Figure 3 is an end elevation of a portion of the secondary member of the
motor, and
Figure 4 is a sectional view taken on line x-x of Figure 3.
1 is the main frame of the machine which is provided internally with a
laminated core, 2, provided with ventilating ducts or channels 3 and with slots
in which are located the coils 6 forming the primary member which are con-
nected to the external circuit. The winding of these coils may be of any suit-
able description. 7 are end caps or plates secured to the main "frame 1.
The secondary member comprises a spider 8 mounted on the shaft 9 and pro-
vided on its external periphery with a laminated core 10 which has ribbed spacing
The core is pro-
plates 4 at intervals, so as to provide ventilating channels.
vided with longitudinal slots 11 in which are located bar conductors 12 each
of which is surrounded by an insulating sheath 13 and projects some distance
beyond the ends of the core. The resistance rings connecting the ends of these
bar conductors are L-shaped in cross section having a main portion 14 of con-
siderable thickness, to which the bars 12 are connected by means of bolts 18 and
nuts 19, the bars being counter-sunk to receive the heads of the bolts. Spring
washers 20 are employed between the rings 14 and the nuts 19 in order to provide
for unequal expansion of the metals employed and prevent the ring 14 becoming
disconnected from the bars 12. The resistance ring has also, in addition to the

page_text: main portion 14, a thin annular plate 15 projecting inwardly towards the shaft
of the machine, and this plate 15 is provided with radial blades 16 and 16ª pre-
ferably alternating in position, the former being thicker than the latter and also
of greater width. The portions of the blades 16 which project inwardly towards
the spiders 8 are provided with shoulders which receive the outer flanged por-
tion 17 of the spider, thus serving to centre the ring and to assist in retaining it
in position.
During the operation of the motor when the secondary member rotates, the
blades 16 and 16 serve as fans to set up currents of air which circulate through
and around the cores of the machine and between the conductors and thus keep
the temperature down to a safe limit.
Datad this 20th days of trout 1808
W. P. THOMPSON & Co.,
322, High Holborn, London, W.C., Patent Agents for the Applicant.
I, REGINALD BELFIELD, of 32, Victoria Street, in the City of Westminster,
England, Electrician, 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:--
My invention relates to induction motors such as are usually operated by two
or more currents differing in phase.
With motors of this description an additional resistance is generally required
in the secondary circuit and this has been provided for by permanently connect-
ing the ends of the conductor bars forming such secondary circuit through rings
or plates of comparatively high resistance.
According to my invention I provide these rings or plates with radial blades
which when the secondary member is rotated produce air currents and thereby
ventilate the same; and in order to provide for efficient ventilation of both
members I construct the primary member with ducts or channels concentric with
and in the same plane as those in the secondary member; furthermore I prevent
said rings from being separated from the bars owing to unequal expansion of the
metals when the temperature changes by connecting the parts together with bolts
and nuts having spring washers.
In the drawings accompanying my Provisional Specification,
Figure 1 is an end elevation of a motor constructed in accordance with my
invention, the end plates or covers being removed.
Figure 2 is a detail sectional view of a portion of the machine shewn in
Figure 1, portions of the end covers being also shewn.
Figure 3 is an end elevation of a portion of the secondary member of the
motor, and
Figure 4 is a sectional view taken on line - of Figure 3.
1 is the main frame of the machine which is provided internally with a
laminated core 2, provided with ventilating ducts or channels 3 and with slots
in which are located the coils 6 forming the primary member which are con-
nected to the external circuit. The winding of these coils may be of any suit-
able description. 7 are end caps or plates secured to the main frame 1.
The secondary member comprises a spider 8 mounted on the shaft 9 and pro-
vided on its external periphery with a laminated core 10 which has ribbed sparing
plates 4 at intervals so as to provide ventilating channels 10" which as shewn in

page_text: Figure 2 are in the same plane as the channels 3 in the primary members. The
core is provided with longitudinal slots 11 in which are located bar conductors 12
each of which is surrounded by an insulating sheath 13 and projects some distance
beyond the ends of the core. The resistance rings connecting the ends of these
bar conductors are L-shaped in cross section having a main portion 14 of con-
siderable thickness, to which the bars 12 are connected by means of bolts 18 and
nuts 19, the bars being counter-sunk to receive the heads of the bolts. Spring-
washers 20 are employed between the rings 14 and the nuts 19 in order to provide
for unequal expansion of the metals employed and prevent the ring 14 becoming
disconnected from the bars 12. The resistance ring has also, in addition to the
main portion 14, a thin annular plate 15 projecting inwardly towards the shaft
of the machine, and this plate 15 is provided with radial blades 16 and 16 pre-
ferably alternating in position, the former being thicker than the latter and also
of greater width. The portions of the blades 16 which project inwardly towards
the spiders 8 are provided with shoulders which receive the outer flanged por-
tion 17 of the spider, thus serving to centre the ring and to assist in retaining it
in position.
During the operation of the motor when the secondary member rotates, the
blades 16 and 16 serve as fans to set up currents of air which circulate through
and around the cores of the machine and between the conductors and thus keep
the temperature down to a safe limit.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, as communicated to
me by my foreign correspondent, I declare that what I claim is:-
1) For an electric motor of the kind described, a secondary member in which
the rings connecting the ends of the bar conductors are provided with radial
blades for the purpose specified.
2) The modification in which some or all of the blades are provided with
shoulders to engage with the outer flanges of the spider supporting the secondary
member and serve to centre the resistance rings.
3) An induction motor in which the secondary member has a laminated core
core provided with ventilating channels and the primary member has a laminated
core provided with ventilating channels which are concentric with and in the
same plane as those in the secondary member, substantially as described.
4) Electric motors constructed substantially as described.
HOMPSON
HITOMPSON
WP. TH
Of London, Liverpool, Manchester and Birmingham.