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Патент USA US2403665

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July 9, 1946'.
2,403,665
J. D. LEWIS
ELECTRIC MOTOR
" Filed July 7, 1943
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INVENTOR
ATTORNEY
July 9, 1946.
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J. D. LEWIS
2,403,665
ELECTRIC MOTOR
Filed July 7, 1943
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ATTORNEY
July 9, 1946.
2,403,665
J. D LEWIS
ELECTRIC MOTOR
Filed July 7, 1945
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ATTORNEY
Patented July 9, 1946
2,403,665,
UNITED s'rA'rEs PATENT OFFICE
2.403.665
ELECTRIC MOTOR
Jacob Daniel Lewis, Yonkers. N. Y., asaignor to
Otis Elevator Company, New York, N. Y., a
corporation of New Jersey
Application July 7, 1943, Serial No. 493,792
9 Claims. (Cl. 172-280)
,
1
2
I
The invention relates to electric motors.
In many buildings, the supply of electric power
to the building is polyphase alternating current.
The ratio or the number of poles productd on al
ternating current excitation to the number pro
duced on direct current excitation is such as to
It is of advantage in many instances of industrial
‘case an amount of current ?ow through the
motor applications in such buildings to utilize 5 armature conductors su?icient to cause opera
polyphase alternating current motors. In some of
tion oi’ the motor as a polyphase induction motor
for the particular duty to which it is applied.
these instances, it is desirable to provide motors
which may be operated at different speeds. For
Since the speed of the motor operating as a direct
example, in elevator installations, it is desirable
current motor is dependent upon the voltage im
to provide one speed for full speed operation of 10 pressed on the armature, the number of armature
the elevator and another speed slow enough for
conductors, and the ?eld strength, by proper
the elevator to make accurate stops at the land
choice of these factors different speeds may be ob
ings. This is especially the case where levelling
tained. Thus the motor may be caused to run
mechanism is provided for bringing the car to
as a direct current motor faster or slower or at
the landing level in case it underruns or over 15 the same speed as when operated as a polyphase
runs a landing in stopping,
induction motor. However, as the invention is
The principal object of the invention is to pro
especially applicable to elevator hoisting motors,
vide a motor which may be operated at full speed
it will be described as applied to such motor with
as 9. polyphase alternating current motor and
the motor operated as a polyphase induction mo
which may also be operated at a very slow speed. 20 tor for fast speed operation and as a direct cur-'
The invention involves a motor which may be
rent motor for slow speed operation.
operated as a polyphase alternating current mo
Features and advantages of the invention will
. tor and
also as a direct current motor. In car
‘
be apparent from the above statements, the de
rying out the invention according to the arrange
scription which follows and appended claims.
In the drawings:
ment which will be described, the stator or ?eld
winding of the motor is arranged for connection
Figure 1 is a developed diagram of the stator
to a source, of polyphase alternating current or to
winding of a motor embodying the invention;
a source of direct current. It is wound so that
Figure 2 is a simpli?ed schematic wiring dia
when certain points thereon are connected to the
gram of the stator winding shown in Figure 1;
Figure 3 is a magnetomotive force diagram for
direct current source it acts as a direct current 30
?eld winding to provide a stationary ?eld of a
the coils of the stator winding of Figure 1;
certain‘ number of pairs of poles and so that
Figure 4 is a resultant ?ux diagram for the
when certain points thereon are connected to the
same;
polyphase alternating current since it acts as a
Figure 5 is a developed diagram of the rotor or
polyphase alternating current stator winding to 35 armature winding of a/motor having the stator
provide a rotating ?eld of a di?erent number of
pairs of poles. The rotor or armature of the motor
is provided with a commutator. It is wound for the
winding of Figure 1;
,
Figure 6 is a simpli?ed wiring diagram in
“across-the-line" form of a control system for a
number of poles provided by the field winding
motor, having the windings of Figures 1 and 5,
when connected to the direct current source and 40 utilized as an elevator hoisting motor; and
has equalizers connecting points having no differ
Figure SS is a key diagram for Figure 6 show
ence in electrical potential. Thus, when the ?eld
ing the electromagnetic switches in spindle form
winding is connected to the direct current source
with the contacts and coils arranged on the spin
and the brushes for the commutator are also con
dles in horizontal alignment with the correspond
nected to a direct current source, the rotor acts 45 ing contacts and coils in the wiring diagram.
as a direct current armature and the motor runs
An embodiment of the invention will be de
as a direct current motor.
The number of poles
produced by the ?eld winding when connected to
' scribed in which the motor operates as a six pole
alternating current motor and as a four pole di
the alternating current source is such that a dif
rect current motor.
'
ierence of potential exists between the points on 50' Considering ?rst the stator winding for oper
the armature winding joined by the equalizers to
ation of the motor as a polyphase alternating
cause current ?ow through the armature con
current motor, the stator winding is illustrated
ductors by way of the equalizers. Thus, on alter
as a six pole three phase lap winding arranged in
nating current excitation the rotor becomes a
36 slots and distributed in two slots per phase per
polyphase induction motor squirrel cage rotor. 65 pole. In the developed view shown in Figure 1,
asoasss
.
3
4
the coils are designated la, 2a, etc., while the
slots are designated lb, 2b, etc. Because of space
conditions, reference characters are applied to
only the first nine of each. The phase windings
are differentiated by heavy, light and dot-dash
lines. The pairs of coils per phase per pole are
connected by short Jumpers designated 21 while
other connections for the coils are made by long
.
ing arranged in two groups and connected in '
parallel, which when excited from a source of
three phase alternating current as indicated pro
vides a six pole rotating ?eld.
'
,
For direct current excitation, terminals 4| and
41 are connected to a source. of direct current while
the other terminals are not connected to a source.
Assuming current flow in the direction of the
Jumpers designated 38, it being understood that
arrows in Figure 2 and as before clockwise cur
the long Jumpers at the ends in Figure 1, specially 10 rent iiow through a coil to provide excitation for
designated Ila, 38b and 28c are connected, being
a north pole, coils lila and 28a provide excitation
broken oil because of the developed view. Seven
leads 4|! connect points in the stator winding to
terminals designated H, 42, 43, 44, 45, 48 and 41.
for a south pole, coils 23a and 24a provide ex
citation for a north pole, etc. Or grouping the
coils, coils Ia, 2a, la, 4a, la, la, ‘la, la and la
The connections of the coils will be more read 15 provide excitation for a north pole, the next nine
ily understood from the simplified wiring diagram
coils, namely Ila through Ila provide excitation
shown in Figure 2. In this ?gure, the coils are
for a south pole, the next nine coils provide ex
represented by circles. The coils are of identi
citation for a north pole, and the remaining nine
cal form and therefore it may be assumed that
coils provide excitation for a south pole.
the circuit through each coil in Figure 2 will 20
The excitation provided by the coils, when con
always be from the entering point toward the
nected to a direct current source, as described
top, regardless of whether the circuit enters the
above, is diagrammatically illustrated in Figures
coil from the right or from the left. Thus, as
3 and 4. Figures 3 and 4,'being of the same scale
suming an instant in which current enters coil
as Figure 1, may be aligned therewith to facilitate
I from the left, the current how in the coil is 25 an understanding of the direct current excita
clockwise, whereas at an instant in which cur
tion. The horizontal line 48 is a reference line
rent enters coil I from the right. the current flow
above which the excitation may be regarded as
in the coil is counterclockwise.
.
positive, 1. e., to provide north pole excitation
The coils are arranged in vertical columns in
and below which as negative, 1. e., to provide south
accordance with their phase, there being six col 30 pole excitation. The numerals I to 28 inclusive
umns and six rows inasmuch as there are two
indicate reference points corresponding to the
coils per phase per pole. For convenience of
slots of the stator. In Figure 3, the magnetome
switching, the coils of each phase winding are
tive force of each coil is represented by a rec
divided into two groups arranged for connection
tangular block 49. The length of these rectangles
in parallel to provide a delta connected stator 35 corresponds to the pitch of the coils while the
winding. This arrangement also facilitates ob
height of each coil corresponds to the magnitude
taining the desired resistance for direct current
of the magnetomotive force. Thus the magneto
excitation. For example, coils Ia, 2a, 32a, Iia,
motive force due to coil is for example extends
25a and 25a constitute one group of phase I,
over the face of the stator from slot ID to slot 5b,
while coils 8a, ‘la, I3a, I4a, 20a and Isa consti 40 or from points I to 5 and is positive.
tute the other group, and these groups are con
The resultant magnetomotive force is the alge
nected in parallel between terminals 4i and 42,
braic sum of the heights of these rectangles over
41, the latter two terminals being connected to
the area encompassed by the respective coils.
gether for alternating current excitation. Termi
This sum is shown in Figure 4>in which the line
nals 42 and 43 are connected to one phase of the
iii represents the resultant magnetomotive force
‘supply lines, terminal 4| is connected to termi
or, since the flux density produced by this mag
nals 48 and 41, the three of which are connected
netomotive force is directly proportional to the
to another phase of the supply lines, and termi
_ magnetomotive force, the line 50 is a diagram
nals 44 and 45 are connected together and to 50 matic representation of the ?ux density due to
the remaining phase of the supply lines, all of
the stator winding on direct current excitation
which will be seen from the description which ‘ and the- area under this line is the total ?ux
follows in connection with Figure 6. Thus the
entering the armature. The ?ux density is a
phase windings are connected delta. Assume,
maximum between slots corresponding to points
for example an instant in which current ?ow is
55 4 and Ill, I3 and I9, 22 and 28, and ii and I.
maximum into terminals 4|, 48 and 41 and thus
Between the slots corresponding to points I I and
?ows out half from terminals 42, 43 and the other
I2, 20 and 2|, 29 and Ill, and 2 and I, the ?ux
half from terminals 44 and 45. Under such con
density is zero, thereby providing neutral zones
ditions. current ?ows clockwise in coils Ia, 2a,
for the setting of the commutator brushes. Thus
28a, 26a, Ita, No, 230, 24a, Ilia. 38a, Ila, I2a 60 a four pole stationary field is provided when the
and counterclockwise in coils 32a, 3Ia, 8a, ‘Ia, 20a.
its, Ba, Ba, liia, 29a, Ila and Ho. Assuming
clockwise current ?ow to produce excitation for
stator winding is connected to a source of direct
current.
The rotor or armature winding is illustrated
a north pole. in phase I coils Ia and 2a provide
as a multiple winding of the type used on direct
excitation for a north pole. coils ‘Ia and to pro 65 current armatures, wound for a four pole station
vide excitation for a south Pole, etc. and in
ary field and arranged in 24 slots. In the devel
phase III coils Ia and 6a provide excitation for
a south pole, coils Ila and I 2a provide excita
oped view shown in Figure 5, the coils of the
armature winding are designated Ic. 20, etc.,
tion for a north pole, etc.
while the slots are designated Id, 2d, etc. The
Therefore, as a re
sultant. coils "a, Ila, Ia and 20 provide excita 70 two terminals of each coil are connected to adja
tion for a full north pole, coils in, 8a, ‘Ia and Ba
cent commutator bars, these bars being desig
provide excitation for the next full south pole.
nated Ie, 2e. etc. A full pitch winding is illus
etc., for a total of six poles. Thus a standard
trated, the sides of coil Ic, for example, being
three phase delta connected six pole stator wind
placed in slots Id and ‘Id. The four brushes
in: is provided with the coils of each phase wind 75 are designated 65, 66, 61 and 68, like brushes
9,408,665 ''
5
.
being connected together ‘and to terminals II and
10. Corresponding points on the armature wind
ing are connected together by equalizing con- .
nectors designated ll, 52, etc., 12 equalizing con
nectors being illustrated. For convenience, these
equalizing connectors are illustrated as con
nected to the commutator bars.
e
Figure 5 is of the same scale as Figures 1, 3 and
4 and may be aligned therewith to facilitate
g
6
v
former TB. is provided for supplying direct cur
rent for generator separately excited neld wind-'
ing GP, for the operating coils of the electro
magnetic switches and for the brake release coil
BR. R ‘designates a resistance in circuit with
generator field winding GF. CA is a condenser
utilized for timing one of the control switches.
GOV designates a governor utilized in the control
system.
.
The control system illustrated is of the type in
understanding of the operation. Reference lines l0
which both the starting and stopping of the car
‘II are illustrated above the'armature winding
is controlled by an operator in the car. A car
and in line witliithef-‘connecting points of the
switch is provided in the car, the car switch seg
equalizing connectors. These lines are laid off at
ment being designated CS and the stationary
the bottom in accordance with the spacing in
electrical degrees on direct current excitation 15 contacts engaged thereby being designated CUI,
CU! and CU! for up car travel and CDI, CD2 and
and at the top in accordance with the spacing
CD3 for down car travel. UL and DL are con
in electrical degreeson alternating current exci
tacts of levelling mechanism utilized to bring the
tation. Thus it is seen that on direct current
car to an exact landing level in case it underruns
excitation the equalizing connectors connect
points on the armature winding spaceid 360 elec 20 or overruns a floor in stopping.
The electromagnetic switches have been des
- trical degrees and therefore of the same poten
ignated as follows:
tial so that there is no current flow in the equal
izing connectors other than that which might
be due to some irregularity in manufacture.
B _ Stator‘ alternating current excitation switches
On alternating current ‘excitation, however, 25 C
there being six poles instead of four, each line
D, Stator direct current excitation switch
'H is 45 electrical degrees apart instead of 30 as
DF, Down fast speed switch
in direct current excitation. Therefore, on alter
Ds,'Down slow speed switch
nating current excitation the equalizing connec
E, Driving motor switch
tors connect points onthe armature winding Il? 30 F, Armature direct current control switch
(equivalent 180) electrical degrees apart so that
G, Speed responsive switch
these points are of equal but opposite potential.
UF, Up fast speed switch
Thus, on alternating current operation the arma
US, Up slow speed switch
ture acts in effect as a definite pitch squirrel
X, Up fast speed interlock switch
cage rotor winding.
85 Y, Down fast speed interlock switch
A
Reference may now be had to Figure 6 which
illustrates a control system for the above de
scribed motor utilized as an elevator hoisting
motor. For convenience, a simple form of con
trol system has been illustrated and various con
trol and safety elements are not shown. The
circuits are shown in “straight" or "across-the
line" form in which the coils and contacts of
the ‘electromagnetic switches are separated in
such‘ manner as to render the circuits as simple
and direct as possible. Therelationship of these
coils and contacts may be seen from Figure 68
,
.
Throughout the description which follows these '
letters will be applied to the coils of the above
designated switches. Also, with reference nu
merals appended thereto they will be applied to
the contacts of these switches, as for example
contacts Al.
To start the car in the up direction, car switch
segment CS is moved into position to bridge con
tacts CUI. GUI and CU3. The bridging of con
tacts GUI and CUI completes a circuit for the
coil of up fast speed interlock switch X. This
switch operates to engage contacts XI and to
where the switches are arranged in alphabetical
separate contacts X2. The separation of con- ’
order and shown in spindle form with the coils
and contacts aligned horizontally with the coils 60 tacts X2 prevents the operation of up slow speed
switch US and armature direct current control
and contacts which they indicate in the wir
switch F as a result of the bridging of car switch-1
ing diagram.
'
contacts GUI and CU2. The engagement of con
The alternating current supply mains are des
tacts Xi completes a circuit for the coil of up
ignated I, II and III. A triple pole manually
operated main line switch designated ML is pro 55 fast speed switch UF. Switch UF, upon opera
tion, engages contacts UF'I, UF2, UFI and U1"
vided for controlling the'supply of current from
and separates contacts UFU. Contacts UFI are
the supply mains. The stator winding of the
interlock contacts in the circuit for the coil of
motor is designated EMS while the armature
down fast speed switch DF. Contacts UFI and
winding, which is illustrated as a conventional
direct current armature, is designated EMA. A 60 UF2 establish direction for the stator winding
EMS of the hoisting motor, while contacts UF!
direct current generator is illustrated'for sup
complete the circuit for brake release coil BR.
plying current to the elevator motor armature
winding on direct current operation. The gen
erator armature is designated GA, its separately
excited ?eld winding GF and its‘series field wind
ing GSF. This generator is illustrated as driven
by a three phase squirrel cage induction motor,
the stator winding of which is designated DMS
and the rotor of which is ‘designated DMR. Cur
At the same time contacts UFl complete the cir
cuits for the coils of stator alternating current
excitation switches A, B and C. These switches
operate to engage contacts Al, A2, BI and Cl
completing the circuits for the stator winding of
the hoisting motor. The circuit to terminal ll
of the motor is from supply main I through con
rent for the stator winding on direct current 70 tacts UFI and Al. The circuit to terminals 46
and\l1 is from supply main I through contacts
operation is derived from the alternating current
UFI and A2. The circuit to terminals 42 and 43
supply mains through a transformer TR and rec
is from supply main II through contacts Bi. The
tiiler REI connected across a secondary winding
circuit to terminals 44 and 45 is from supply main
of the transformer. Another recti?er RE! con
nected across anothersecondary winding of trans 75 III through contacts UP! and Cl. Thus the phase
mosses
.,
'
7
windings oi the hoisting motor are connected in
delta relationship to the supply mains for a phase
rotation of the applied voltage for up car travel
sothatasthebrakereleasesthecarstartsin
the up direction. This excitation as previously
described provides a six pole rotating ?eld to
cause operation of the hoisting motor at a fast
speed.
coils .of switches US and 1''. Switch 1'', upon
dropping out, breaks the generator armature mo
tor armature loop circuit, while switch US, upon
dropping out, breaks the circuit 101' the generator
separately excited ?eld winding. Switch US also
breaks the circuit for the brake release coil caus
ing the brake to be ‘applied to bring the car to
a stop at the landing level. Also, switch US
As'the car accelerates, the governor switch
breaks the circuit for the coil of switch E which
GOV closes completing a circuit for the coil of 10 drops out to break‘ the circuit for stator winding
speed responsive switch G. Switch G operates
DMS of the generator driving motor, shutting
to engage contacts GI and to separate contacts
down the motor generator set. It also breaks the
G2. The engagement of contacts GI completes
circuit for the coil oi’ switch D which drops out to
a circuit for the coil oi’ driving motor switch E.
disconnect the stator winding from recti?er REI.
Switch E operates to engage contacts ‘El and E2 15
Should the car overrun the landing, down lev
completing a circuit for the driving motor stator
elling contacts DL are engaged at the time of the
winding EMS. The driving motor starts in op
engagement of contacts G2 so that the circuit is
eration, driving generator armature GA.
completed for the coils or down slow speed switch
To stop the car at a landing the car switch
DS and switch F. Switch DS, upon operation,
segment is centered as the car approaches the 20 engages contacts DSI, D82, D83 and DS‘ and
landing, breaking the circuits for the coils of
separates interlockoontacts DSI. Switch F, as
switches X, UF, A, B and C. Switches UF, A, B
above, engages contacts Fl to complete the gen
and C, upon dropping out, break the circuits for
erator armature motor.v armature loop circuit.
the stator winding of the hoisting motor.
Contacts DSI and D82 establish a circuit for gen
dropping out of switch Ur‘ also breaks, the cir 25 erator ?eld winding GP‘ for current ?ow there
cuit for brake release coil BR so that the brake
through in the opposite direction so that gen
is applied to slow down the car.
erator armature GA applies voltage to the hoist
As the speed of the car decreases to a certain
ing motor armature winding to move the car in
value, governor switch GOV opens to break the
the down direction. Contacts DSI reestablish
circuit for the coil of speed responsive switch G. 30 the
circuit for the release coil of the brake with
Switch G, upon dropping out. engages contacts
the result that as the car is brought to a stop it
G2 and separates contacts GI. Contacts G2 com
is restarted in the‘ down direction and returned
plate the circuit for the coil 01' stator direct cur
to the ?oor. As the car reaches the landing,
rent excitation switch D through contacts El, G2,
down levelling contacts DL separate breaking the
X2 and YI. Switch D, upon operation, separates 35 circuit for the coils of switches DS and 1“. These
contacts D2 to prevent energization of the coils
switches drop out to cause the application oi’
of fast speed switches U1" and DF. It also en
power to the hoisting motor armature to be dis
gages contacts DI to connect terminals It and
continued and the brake to be applied to bring
(‘I oi’ the stator winding EMS oi the hoisting
the car to a stop at the landing level. Also switch
motor to recti?er REI. This causes excitation 40 Etdrops out to shut down the motor generator
of the stator of the hoisting motor as a tour pole
stationary ?eld as previously explained.
Assume that the car has underrun the ?oor so
that up levelling contacts UL are engaged at the
time contacts G2 engage. Under such conditions,
contacts G2 also complete a circuit through con
tacts‘UL, coll oi up slow speed switch US, inter
lock contacts DSi, coil of armature direct cur
rent control switch F and contacts G2, X2 and
YI, causing the operation of switches US and
. 1".
Switch US, upon operation, engages contacts
USI, U82, U82 and US‘ and separates interlock
contacts USU, while switch F, upon operation,
engages contacts PI.
The engagement of con
tacts Fl connects terminals II and 10 of the
hoisting motor armature winding across the gen
erator armature GA. The engagement of con
tacts USI and U82 completes a circuit through
generator separately excited ?eld winding GF in
se .
The car is started in the down direction by
moving car switch segment CS downwardly to
bridge contacts CDI, CD2 and CD3. This causes
operation of down fast speed interlock switch Y
and down fast speed switch DF instead of
switches X and UF. Switch DF establishes di
rection for the elevator hoisting motor stator
winding so that upon completion oi’ the circuit
for this winding the phase rotation of the ap
plied voltage is for operating the car in the down
direction. Otherwise operation of the system is
similar to that set forth for starting the car in
the up direction and will not be further described.
The car may be operated at slow speed by mov
ing the car switch segment into position bridg
ing only contacts GUI and CU2 or CDI and CD2.
In such event switch F and‘ either switch US or
switch D8 are operated to cause operation of
a direction to cause generator armature GA to 60 the hoisting motor on direct current as above de
apply voltage to the hoisting motor winding of
a polarity for continued up car travel. At the
same time contacts U82 reestablish the circuit
for the brake release coil to cause release of the
brake. Contacts USI reestablish the circuit for
scribed.
'
‘
'
Thus it is seen that a motor is provided which
acts as a polyphase alternating current motor for
fast speed operation and which may be operated
at a slow speed preparatory to stopping or for
the coil of switch E, momentarily broken by the
the levelling operation. There is no increase in
separation of contacts GI, condenser CA main
size of the motor over that for a single speed
taining switch E operated during this period.
polyphase alternating current motor to provide
The voltage 01’ ‘generator armature GA is cor
such fast speed operation. Owing to the fact that
related to the strength 01' the excitation of the 70 there is no ?xed relation between the speed on
stator winding and the number oi’ armature con
alternating current excitation and that on direct
ductors to cause the hoisting motor to operate
current excitation, as in the case for example oi.’
as a direct current motor at a slow speed. '
alternating
current motors o! di?'erent pole num-I
As the car reaches the landing up levelling con
bers, the speed on direct current operation may
, tacts UL separate. breaking the circuit for the 75 be as low as required to obtain the desired speed
2,408,665
'
\9
_
,
of operation or the cai'\As the power required
to operate the car at slow peed is only a fraction
of that required to operate it at fast-speed, a I
small motor generator set may be utilized and
the commutator of the motor may be small.
While described for only one slow speed on direct
current operation, it is to be understood that
more than one speed may be provided, as for ex
10
be understood that the invention is applicable
to polyphase alternating current excitation of
other numbers of phases. Also, while the stator
winding has been described as adapted for mesh
connection, it may be connected star. The mesh
connection, however, admits of a more simple
switching mechanism and minimizes the number
of leads from the motor.
As many changes could be made in the above
ample, by controlling resistance in circuit with
the generator ?eld winding. The system of con 10 construction and many apparently widely differ
ent embodiments of this invention could be made
trol illustrated is simply by way of example and,
without departing from the scope thereof, it is
although a car switch control elevator system
intended that all matter contained in the above
has been described, the invention is applicable to
description or shown in the accompanying draw
other forms of elevator systems such as push but
ton control systems.
'
-
>
An important feature of the invention is the
provision of an armature winding having equaliz
15 ings shall be interpreted as illustrative and not
in a limiting sense.
ing connectors joining points of equal potential
What is claimed is:
1. An electric motor having a ?eld winding the
on direct current excitation and which serve on
coils of which are so wound and connected that
alternating current excitation as connectors for 20 when certain points ‘on the winding are connected
to a source of direct current a stationary ?eld of
current ?ow in the armature conductors. This is
at least two pairs of poles is provided and when
satis?ed by a multiple wound armature with
certain points thereon are connected to a source
equalizing connectors for all coils but it is to be
- of polyphase alternating current a rotating ?eld
understood that a less number of equalizing con
nectors may be employed, as for example by 25 of a different number of pairs of stationary poles
is provided, and an armature winding wound for
omitting every other one. The actual arrange
the number of said pairs of stationary poles and
ment of the armature winding depends on the
having equalizing conductors connecting points
stator winding. The stator winding should pro
of equal potential when the ?eld winding is con
vide at least four poles on direct current excita
tion as otherwise no points of equal potential 30 nected to said source of direct current.
2. An electric motor adapted for operation on
are provided on the armature winding to which
polyphase alternating current and on direct cur
equalizing connections may be made. On alter
rent comprising; a ?eld winding having a plu
nating current excitation of the stator winding,
rality of coils so wound and connected that when
a difference in potential is had at the points of
connection oi.‘ the equalizing connectors to cause 35 certain points on the winding are connected to
a source of direct current a stationary ?eld of at
current ?ow in the armature conductors when
least two pairs of poles is provided and when
the number of poles is less than the number of
certain points on the winding are connected to
poles on direct current excitation or greater than
a source of polyphase alternating current a ro
but not a multiple of the number of poles on
direct current excitation. However, in a great 40 tating ?eld of a different number of pairs of poles
is provided; and an armature provided. with a
many of these combinations, the current ?ow in
commutator and. wound for the number of poles
the armature conductors on alternating current
of the stationary ?eld and having equalizers con
excitation would be insufficient for satisfactory
necting points on the armature ‘winding 360 elec
operation. For elevators, it is preferred to have
a combination of pole numbers in which on alter 45 trical degrees apart when the ?eld winding is
connected for direct current operation; the num
nating current excitation the points of connection
ber of poles of the ?eld winding when it is con
of the equalizing connectors are not less than 120
nected for alternating current operation being so
electrical degrees or more than 240 electrical de
selected that the points of connection of the
grees apart or any equivalent such as not less
equalizers to the armature winding are of a num
50
than 480 or more than 600 electrical degrees
ber of electrical degrees apart such that current
apart. Thus for example, a stator wound to pro
?ows in the armature winding by way of the
vide eight poles on alternating current excitation
equalizers.
'
and six poles on direct current excitation is con
3. An electric motor having a ?eld winding and
sidered practical. A combination in which the o a rotatable winding, said ?eld winding being so
points of connection of the equalizing connectors
wound and having leads from such points there
on alternating current excitation are 180 electri
cal degrees apart, such as the combination illus
trated, or equivalent would be an optimum ar
on that when certain of said leads are connected
to a source of direct current there is provided a
rangement.
stationary ?eld of at least two pairs of poles and
polyphase alternating current hoisting motor is
determined by the requirements of the particu
source of polyphase alternating current there is
provided a rotating ?eld of a number of pairs of
poles which is a fraction of or prime to the num
In elevator operation, the number of poles of a 60 when certain of said leads are connected to a
lar installation. In the case of geared machines,
such factors as gear size and sheave diameter
have a direct bearing on the number of poles.
Thus in the case of elevators, the number of
ber of ,pairs of poles of the stationary ?eld, said
rotatable winding being wound for the number
of said pairs of stationary poles and to have points
of equal electrical potential when the ?eld wind
stator poles on alternating current excitation is
ing is excited to provide said stationary ?eld,
a given factor so that the stator is wound and
equalizing conductors connecting said points of
provision for connection is made to provide a dif
ferent number of poles on direct current excita 70 equal potential, said conductors serving as end
connectors for current ?ovv between conductors
tion. It is preferred to provide a low number of
poles on direct current excitation to minimize I of said rotatable winding when said ?eld winding
is excited to provide said rotating ?eld to cause
the number of brushes.
operation of said motor as a polyphase induction
While described as applied to a three phase
motor at a certain speed, a commutator for said
motor on alternating current excitation, it is to
i
2,408,665
'
='-
11‘
rotatable winding, and brushes for said commu
tator adapted for connection to a source oi di
rect current when said ?eld winding is excited to
provide said stationary ?eld to cause operation
of said motor as a direct current motor at a
certain speed.
4. An electric motor having a ?eld winding and
an- armature winding, said armature winding be
ing wound for at least two pairs oi stationary ?eld
12
ing ?eld oi adiiierent number of pairs of poles is
provided; and an armature wound for the num
ber of poles of the stationary ?eld and provided
with a commutator and brushes and adapted
when the brushes are connected to a source 01'
direct current of a certain voltage with direct
current of a certain value supplied to the ?eld
winding to cause operation of the motor at a
certain speed, said armature having equalizers
poles and to have corresponding points under like 10 connecting points on the armature winding-360
poles of equal electrical potential, equalizing con
electrical degrees apart when the ?eld winding
ductors connecting said points, a commutator for
is connected for direct current operation; the
said armature winding, brushes for said commu
number of poles oi.’ the ?eld winding when it is
tator, said stationary ?eld winding being wound
connected for alternating current operation be
and adapted, when certain points thereon are ll ing so selected that the points of connection of
connected to a source of direct current, to provide
a stationary ?eld oi’ the number of pairs of poles
for which said armature winding is wound to
cause with said brushes connected to a source 0!
direct current operation of the motor as a direct
current motor and, when certain points there
on are connected to a source 01' polyphase alter
nating current, to provide a rotating ?eld o! a
number of pairs oipoles to cause current ?ow be
tween conductors of said armature winding
through said equalizing conductors as end con
nectors sumcient to cause operation of said motor
as a polyphase induction motor.
,
5. An. electric motor having a ?eld winding and
an armature winding, said armature winding be
ing multiple wound for at least two pairs 01 sta
tionary ?eld poles-and having equalizing con
the equalizers to the armature winding are of a
number 0! electrical degrees apart such that cur
rent ?ows in the armature winding through the
equalizers to cause operation of the motor at a
speed determined by the number of poles.
8. An electric motor adapted for operation on
polyphase alternating current and on direct cur
rent comprising; a stator having a polyphase lap
winding with its coils so connected that when
certain points on the winding are connected to
a source of polyphase alternating current a re
tating ?eld of a certain number of pairs of poles
is provided and when certain points on the wind_
ing are
connected
to
a
source
or
direct
current a stationary ?eld or at least two
pairs of poles is provided, the number oi’ pairs 01'
poles of the rotating field being di?erent from
ductors connecting corresponding points thereon
the number of pairs of poles of the stationary
spaced 360 electrical degrees under such station
?eld; and an armature having a multiple wind
ary ?eld excitation, the coils of said ?eld winding 35 ing wound for the number of poles of the sta
being so wound and connected that, when cer
tionary ?eld, said armature being provided with
tain points on the ?eld winding are connected to
a commutator and brushes and having equalizers
a source of direct current, there is provided a
connecting points on the armature winding 360
stationary ?eld oi the number of pairs of poles
electrical degrees apart when the ?eld winding
for which said armature winding is wound and, 40 is connected for direct current operation; the
when certain points thereon are connected to a
number of poles oi’ the ?eld winding when it is
source of polyphase alternating current, there is
connected for alternating current operation be
provided a rotating ?eld of a number of pairs
ing so selected that the points 01' connection or
of poles to cause said points on said armature
the equalizers to the armature winding are of a
winding to be spaced a number of electrical
number of electrical degrees apart such that cur
degrees within a range of 120 and 240 electrical
rent ?ows in the armature winding through the
degrees or equivalent.
equalizers as end connectors to cause operation
6. An electric motor having a ?eld winding and
of the motor as a polyphase squirrel cage induc
an armature winding, said armature winding be
tion motor at a fast speed determined by the
ing multiple wound for at least two pairs of sta 50 number oi’ pairs of poles, and the armature be
tionary ?eld poles and having equalizing con
ing adapted when the brushes are connected to a
ductors connecting corresponding points there
source of direct current of a certain voltage with
on spaced 360 electrical degrees under such sta
direct current of a certain value supplied to the
tionary ?eld excitation, said ?eld winding being
field winding to cause operation of the motor
wound and adapted, when certain points thereon
as a direct current motor at a slow speed.
are connected to a source oi’ direct current, to
9. An electric motor adapted for operation on
provide a stationary ?eld oi the number of pairs
three-phase alternating current and On direct
oi’ poles for which said armature winding is
current comprising: a stator having a three
wound and, when certain points thereon are con
phase lap winding distributed in a certain num
nected to a source of polyphase alternating cur
ber of slots per phase per pole and having jump
rent, to provide a rotating ?eld oi.’ a number of
ers so connecting its coils that when certain
pairs oi.’ poles such that the ratio of the number
points on the winding are connected to a source
of said pairs of poles of rotating ?eld to the num
of three-phase alternating current the phase
ber of said pairs oi‘ poles of stationary ?eld is
windings are delta connected and provide a ro
between V; plus any digit including zero and % 65 tating ?eld or a certain number of pairs 01' poles
Plus said digit.
‘
and when certain points on the winding are con
7. An electric motor adapted for operation on
nected to a source 01' direct current a stationary
polyphase alternating current and on direct cur
?eld of at least two pairs of poles is provided,
rent comprising; a ?eld winding having a plu
the number 01' pairs of poles of the rotating ?eld
rality of coils so wound and connected that when 70 being diil'erent from the number of pairs of poles
certain points on the winding are connected to
of the stationary ?eld; and an armature having
a source of direct current a stationary ?eld of at
a multiple winding wound for the number of poles
least two pairs of poles is provided and when cer
of the stationary ?eld. said armature being pro
tain points on the winding are connected to a
vided with a commutator and brushes and having
source of polyphase alternating current a rotat 75 equalizers connecting points on the armature
2,408,665
13
V14,
winding 360 electrical degrees‘ apart when the
?eld winding is connected for direct current op
eration; the number of poles of the ?eld wind
ing when it is connected for alternating current
nectors to cause operation of the motor as a
operation being so selected that the points of con
nection of the equalizers to the armature winding
are of a number of electrical degrees apart such
that the armature acts as a de?nite pitch squir
rel cage rotor with current ?ow in the armature
conductors through the equalizers as end' con- 10
brushes are connected to a source of direct cur
three-phase squirrel cage induction motor at a
fast speed determined by the number of pairs of
poles, and the armature being adapted when the
rent of a certain voltage with direct current of a
certain value supplied to the field winding to
cause operation of the motor as a direct current
motor at a slow speed.
JACOB DANIEL LEWIS.
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