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Nov. 16, 1948.
2,454,136
T. E. M. CARVILLE
TWO-SPEED S/INGLE-PHASE MOTOR
2 Sheets-Sheet 1
Filed Dec. 3, 1946
#191.
WITNESSES:
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2M.
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INVENTOR
771e0a/ore EM Car w'l/e
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ATTORN
Nov. 16, 1948.
T. E. M. CARVILLE
2,454,136
TWO-SPEED SINGLE-PHASE MOTOR
‘ Filed Dec. 3, 1946
WITNESSES:
824 J/
214
2 Sheets-Sheet 2
INVENTOR
Theodore EM Car-ville.
8* 7. r- {é?
A'lTOR N
2,454,136
Patented Nov. 16, 1948
UNITED STATES PATENT OFFICE
2,454,138
TWO-SPEED SINGLE-PHASE MOTOR_
Theodore E. M. Cal-ville, Lima, Ohio, asslgnor to
Westinghouse Electric Corporation, East Pitts
burgh, Pa., a corporation of Pennsylvania
Application December 3, 1946/Serial No. 713,716
8 Claims. (/Cl. 318-224)
2
The present invention relates to two-speed,
single-phase, induction motors, and more par
ticularly to a low-cost, two-speed, single-phase
motor of either the split-phase or the capacitor
start type.
'
.
I
Single-phase induction motors oi the split
phase and capacitor-start types have a. main
primary winding and an auxiliary, or starting,
' primary winding, which are displaced from each
.
.,
structions for obtaining two-speed operation of
single-phase motors require complicated wind
ings or special switches vand are relatively ex
pensive.
.
The principal object or the present invention
is to provide a two-speed, single-phase induction
motor of either the split-phase or the capacitor
start type, which is relatively simple and which
can be built at low cost.
other on the stator oi the motor, preferably by 10 Another object of the invention is to provide
a two-speed, single-phase motor which utilizes
as nearly ninety electrical degrees as possible.
The two windings carry currents which are dis
only one auxiliary, or starting, winding and a
standard starting switch, so that the necessity
placed in phase, the phase di?’erence being pro
for elaborate and complicated windings or spe—
duced by the design of the windings in the split
phase motor, and by connecting a capacitor in 15 cial starting switches is eliminated, and a simple
low-cost construction is obtained.
series with the auxiliary winding in the capacitor
A more, specific object of the invention is to
start motor. In starting such a motor, the two
provide a two-speed single-phase motor utiliz
primary windings are connected in parallel to a
ing two main windings Of different pole numbers,
single-phase supply line, and when the motor has
accelerated to a predetermined speed, the auxil 20 but only one auxiliary, or starting, winding and
a standard starting switch, the auxiliary winding
iary winding is disconnected by a speed-respon
being arranged so that it is capable of cooperat
sive starting switch, usually 0! the centrifugal
type.
,
'
It is often necessary or desirable to be able to
operate motors of this type at two different speeds,
and two-speed single-phase motors have been
built having two main windings, with different
numbers of poles, and two auxiliary windings, one
ing with either one of the two main windings to
develop a starting torque.
The invention will be more fully understood
from the following detailed description, taken in
connection ‘with the accompanying drawings, in
which:
Figure 1 is a diagrammatic, developed view of
for use with each of the main windings. This re
quires a total of four primary windings, which 80 the primary windings of a two-speed motor em
bodying the invention;
involves some di?iculty in winding the motor, and
Fig. 2 is a schematic diagram showing the
considerably increases the cost, as compared to
electrical connections of the motor; and
that of a conventional single-speed motor. Two
Fig. 3 is a diagram similar to Fig. 1 and show
speed motors have also been built having two
main windings of di?erent pole numbers and 35 ing a modi?ed embodiment of the invention.
Fig. 1 shows an illustrative arrangement of
only one auxiliary winding adapted to cooperate
the primary windings of a two-speed motor em
with one of the main windings. A special start
bodying the invention. The windings are shown
ing switch is used arranged so that the motor
developed, and for clarity in illustration, the
always starts on the main winding with which
the auxiliary winding cooperates, and after op 40 three primary windings are shown separated, al
though it will be understood that they are actu
.eration of the starting switch, the motor runs on
ally superimposed in the same slots. The par
either one of the main windings, as determined by
ticular motor shown for the purpose of illustra
a speed selector switch. This construction re
tion has thirty-six slots in its stator core for
quires a special starting switch, which is unde
sirable, and which substantially increases the
cost of the motor.
Another arrangement for
' two-speed single-phase motors utilizes a single
main winding and auxiliary winding, which are
arranged so that the number of poles can be
changed by changing the connections of the
windings. This requires bringing a relatively
large number of leads out of the motor, and re
quires a complicated and expensive external con
trol switch for changing the winding connections
to change the speed. Thus, all of these prior con 55
reception of the windings, the slots being indi
cated by dotted lines and numbered I to 38 in Fig.
1. The motor has a six-pole high-speed main
winding 40, and an eight-pole low-speed main
winding 4|, although it will be obvious that the
invention is applicable to motors having other
combinations of pole numbers. >
The motor also has an auxiliary, or starting,
winding 42, which cooperates with either one of
the main windings, as explained hereinafter.
The six-pole main winding 40, as shown in Fig.
9,454,186 '
conventional arrangement, although other types
of six-pole windings might be used. Thus, each
coils. Thus, the particular winding shown in the
drawings includes wide coils lying in slots 35
and 3, and in slots d and it, which form poles
coil group, which .forms one pole of the winding,
consists of a suitable number of concentrically
arranged coils, two coils being shown in each coil
group. For example, the ?rst coil group at the
left of Fig. 1 consists of a coil lying in slots 2
and t3 and a coil lying in slots l and 6, the two
of one polarity, and wide coils lying in slots 4
and 8, and in slots 39 and 34 which form poles
of opposite polarity. The winding also includes
narrow coils lying in slots iii and ill, and in slots
2t and ill, respectively, which form poles of op
l, is a concentric-coil winding of more or less
posite polarity.
All of the coils of the auxiliary '
coils being connected in series. Similarly, the iii winding are connected in series between a ter~=
next group consists oi a coil lying in slots ii and
l i and a coil lying in slots l and t2, the two coils
being connected in series and wound in the op—
posite direction to the coils of the ?rst group, so
that the adjacent poles formed by these coil 15
rnlnal lead T2 and the common terminal T5.
@nly a single turn of the winding has been shown,
for simplicity, but it will he understood that the‘
coils of the auxiliary winding will usually have
groups are of opposite polarlt .
Six coil groups
may desirably be used because of its low cost.
similar to those described are provided and they
are all connected in series hetween the terminal
lead Ti and a common terminal lead T3. it
The wide coils oi’ the auxiliary winding it
though any suitable type of eight-pole winding
windings, ii the'necessary phase diiierence exists
between the currents in the main and auxiliary
windings. Similarly, the center of the pole of
opposite polarity produced by the coil lying in
slots 9 and L3 is substantially displaced from the
a large number of turns, and a slzein winding
are positioned so that the poles formed by them
will cooperate with poles of either of the main
will be apparent that a more or less conventional 20 windings to produce starting torque. Thus, it
single-phase slrnpole winding is thus provided,
will be seen from the drawing that the coil lying
the instantaneous polarities at a particular in=~
in slots fl and 3 produces a pole having its cen"
ter approximately in slot 6, which is substantially
stant being indicated-on the drawing. §ingle=
midway between the centers of adjacent poles of
turn coils have been shown, hut it will he under=
both the sin-pole winding 06 and the eight-pole
stood that in an actual motor each coil will have
winding (it. Thus, this pole of I the auxiliary
as many turns as necessary, and each of the coil
winding is displaced approximately ninety elec
groups forming the successive poles of the wind=
ing may include more or less than two coils.
trical degrees from the nearest poles oi’ either
of the main windings, and a starting torque is
The low-speed eight-=pole main winding (it is
shown as a conseduent=pole winding with four 30 produced when the auxiliary winding is ener
gized simultaneously with either one of the main
coll groups, each consisting of three coils, al=
might be used. One coil group of the illustrated
winding consists oi‘ a coil lying in slots 2 and 5,
a second coil lying in slots 5 and 6, and a third '
coil lying in slots 38 and ‘l, the three coils being
concentrically arranged and connected in series.
The other three coil groups are similar, and all
centers oi‘ the nearest poles of either of the main
windings, so that this coil also aids in producing
a starting torque. The same is true of the poles
' iour groups are connected in series between the
terminal lead Til and the common terminal lead All formed by the other two wide coils of the B.'Llll-=_'
iliary winding, which are positioned so that their
T8. It will he observed that all the coils oi’ this
centers lie hetween adjacent poles of either of
winding are wound in the same direction, so that
all of the coil groups produce poles oi’ the some
the two main windings. Thus, all four of the
wide coils oi’ the auxiliary winding ()2 are effec
polarity, and consequent poles oi’ opposite polar»
tive in producing starting torque in combination
ity appear in the spaces between the coil groups,
with either one or" the two main windings it and
thus providing an eight-‘pole field, the instanta=
Ill, The two narrow coils of the auxiliary wind
neous polarities, at a particular instant, being in=
ing are almost in line with poles of the main
cheated on the drawing. It will also be observed
that the two main windings (it and iii are dis=
windings and have little effect on the starting
posed in the slots in such a manner that certain 50) torque.
These narrow coils are utilized for the
poles of the two windings are'qliite close together.
purpose of getting sufficient wire into the wind
Thus, for example, the north pole of the sll§~
ing to give it the necessamr high resistance to
pole winding which has its center between slots
obtain the required phase difference between the
8 and d is aligned with the corresponding north
main and auxiliary winding currents, and they
pole of the eight-pole winding, and the south.
are wound to be of opposite polarity so as to
poles on opposite sides of these two poles, while
more or less cancel each other.
not exactly aligned, are separated by substan
The electrical connections of the motor are
tially less than ninety electrical degrees of either
shown in Fig. 2.
common terminal T3, to
winding. This relative positioning oi the two
which one end of each of the three primary wind
main windings is not necessarily essential to the 60 ings is connected, is brought out of the motor as
invention, but it facilitates the design of the
one line lead 138, for connection to a single-phase
auxiliary winding.
supply line. The terminals Til and Ti of the
The auxiliary winding 02 is of unusual design,
main windings are connected to contacts 43d and
based on the fact that it is not necessary for the
rill, respectively, of a selector switch (it, which is
auxiliary winding to have the same number of
connected to the other line lead [ll of the motor
poles as the main winding, in order to develop a
starting torque. In accordance with the inven
tion, therefore, the auxiliary winding is ar=
ranged to have poles which cooperate with cer
through a line switch (it. The other terminal
T2 of the auxiliary winding $2 is connected to a
speed-responsive starting switch
which may
be of the usual centrifugal type, as indicated by
tain poles of both main windings, so that the auir= 70 a dotted connection to the rotor ht“. The other
side of the switch (id is connected to the line lead
iliary winding will cooperate with either main
winding to produce a starting torque. in the
illustrated embodiment of the invention, the aun
iliary winding includes a number of relatively
M through the line switch 48. It will be apparent
that the selector switch on and the line switch
d8 might he combined, if desired, into a single
wide coils and a number of relatively narrow 75 switch having high-speed, low-speed and oil’ po-»
accuse ‘
‘
.
5
eliminates the field distortion in the motor which
may be caused by the ?ux of the narrow coils in
the arrangement of Fig. 1, and thus improves the
starting performance of the motor. Sincethe
wide coils of both sections otthe winding II; are
wound in the same direction, their ?uxes add,
sitions.‘ Any suitable type of rotor ll may be
utilized, preferably carrying a squirrel-cage sec
ondary winding ll.
\
The operation of the motor should now be
obvious. To start the motorion low speed, the
selector switch ll is placed on the contact 44 to
connect the eight-pole winding M to the line.
and the effect oi.’ the winding in developing start
ing torque with either one of the main windings is
the same as described in connection with Fig. 1.
and as soon as the line switch 4| is closed, the
motor will start because the arrangement of the
auxiliary winding 42 is such that it will develop 10
It, should.now be apparent that a two-speed
single-phase motor has been provided which can
be built at relatively low cost, since it requires
only a single auxiliary primary winding and uti
a starting torque with the eight-pole winding, as
described above. The starting switch ll opens
in the usual manner to disconnect the auxiliary
lizes a standardstarting switch. The auxiliary
winding 42 when the ‘motor reaches a prede
termined speed. and the motor continues to run 15 winding itseli may be a skein winding, which is
at its low speed. To operate the motor on high
easilyandq-uickly inserted in, the slots, so that
speed, the selector switch 48 is placed on the con
a low-cost winding islutilized-in this' motor. It ,
will also be noted that it is only necessary to
tact 45 to connect the six-pole winding 40 to the
line, and the operation is then exactly the same
bring. four leads out of the motor, the common
as for the eight-pole winding. since the auxiliary
lead T3, the leads T0 and TI from the two main.v
winding is arranged so that it produces a starting
windings, and a-,lead fromthe starting switch;
torque with either one of the main windings. It
Thus. the external connections of the motor are
simple and easily made.
7
will be obvious that the starting switch ll must
be adjusted to operate at a speed below the lower
' A particular embodiment of the invention has
been shown and described for the purpose of illus
running speed of the motor.
The invention has been described with reference
tration, ‘but it will be apparent thatvarious other
arrangements and combinations of windings are
to six-pole and eight-pole main windings, but
possible utilizing the same basic idea.‘ It isto be
it is to be understood that it is not limited to
this particular combination of pole numbers, but
understood, therefore, that the invention is not
may be applied to any other desired combinations, 80 limited to the particular arrangement described
such as two or four poles, or four and six poles.
above for the purpose of illustration, but in its
The main windings may be of‘ any desired or'
broadest aspects it includes all embodiments and
modi?cations which come within the scope'of the
usual type, and they are preferably disposed so
appended claims.
that at least some of their poles are more or less
in alignment, as explained above. The auxiliary
winding may also be arranged in any suitable
manner to have at least some of its coils disposed
so that their centers lie between adjacent poles
'of both of the main windings, so as to be capable
of developing a starting torque in combination
with either one of the main windings.
'I claim as my invention:
1. A single-phase induction motor having rel
atively rotatable primary and secondary mem
v
The in
bers, a ?rst main primary winding on the
primary member, a second main primary winding
on the primary member, said ?rst andv second
vention is applicable either to split-phase motors,
main primary windings having different numbers
of} poles, means for alternatively connecting one
such as the motor shown for the purpose of illus
tration, or to capacitor-start motors in which a
or the other of said main primary windings to
a single-phase supply line' for operation of the
capacitor is connected in series with the auxiliary 45 motor at diil'erent speeds, a single auxiliary pri
winding, the arrangement of the winding itself
mary winding having a plurality of poles, said
auxiliary-winding being disposed,v on the primary
A modi?ed form of the invention is shown in‘
niember with at least some oi its poles displaced
Figure 3. The six-pole and eight-pole main wind
from poles of the same polarity of both the ?rst
lugs 40 and H shown in this ?gure are the same 50 and second main windings, and means for en
as those shown in Fig. 1, and described above.
er'gizlng the auxiliary winding from ‘said line,
The auxiliary winding 52 shown in this ?gure.
2. A single-phase induction motor having rel
however, differs from that of Figure 1 in being
atively rotatable primary and secondary mem
being the same in either case.
'
divided into two similar sections.
One section
bers, a. ?rst main primary winding on the primary
‘I of the auxiliary winding 52 is substantially the 65 member, a second main primary winding on the
same as the auxiliary winding 42 of Fig. 1 de—
primary member, said. ?rst and second main
scribed above, except that it may have only half
primary windings having different numbers of
as many turns. The other section “of the auxil
poles, means for alternatively connecting one or
iary winding 52 has the same number of wide
the other of said main primary windings to a
60
coils ‘as the section 53, disposed in the same slots,
single-phase supply line for operation of the
and wound in the same direction so as to be of
motor at diiferent speeds. a single auxiliary pri
the same polarity. The two narrow coils of the
mary winding having a plurality of poles, said
section 54 lie in the same slots as the narrow coils
auxiliary winding being disposed on the primary
of the section 53, but are wound in the reverse
member with at least some of its poles displaced
direction so as to be of opposite polarity. The‘
su?iciently
from poles of the same polarity of
two winding sections 83 and M are connected in
both the ?rst and second main windings to cause
series by a conductor 55, and the complete .winding
52 is connected between the terminal lead T2 and
the common terminal lead T3.
the motor to develop a starting torque when the
auxiliary winding is energized simultaneously
The electrical connections of the motor are the . 70 with either‘ one of said main windings, and means
for energizing the auxiliary winding from said
line and for deenergizing the auxiliary winding
when the motor reaches a predetermined speed.
winding sections carry current in opposite direc
3. A single-phase induction motor having a
tions, so that their ?uxes cancel and the resultant
?ux of these coils is substantially zero. This 75 stator member and a rotor member, a ?rst main
same as those shown in Fig. 2, but in this embodi
ment of the invention, the narrow coils of the two
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