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Патент USA US2136695

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Nov. 15, 1938.
-
G; F, LAING
2,136,695
MOTOR CONTROL SYSTEM
' Filed Dec. 20, 1957
4 Zhwentor
Gdrdon F. Laing
(Ittomeg
Patented Nov. 15, 1938'
2,136,695 '
‘UNITED STATES PATENT OFFICE
2,136,695
MOTOR CONTROL SYSTEM
Gordon F. Laing, Minneapolis, Minn” assignor
to Minneapolis-Honeywell Regulator Company,
Minneapolis, Minn., a corporation of Delaware
Application December 20, 1937, Serial No. 180,768
16 Claims. (01. 172-439)
The present invention relates to a motor con
The valve I0 is variably positioned by a motor
trol system and more particularly to one of the ‘generally indicated by the reference numeral
follow-up type wherein a' motor always moves l3. This motor is of the reversible induction
to a position corresponding to that of a control type and is shown as comprising two opposed ro
5 impedance.
‘
tors i4 and IS with which are associated ?eld
It is quite common to use a motor control sys
windings l6 vand I1, respectively. As long as
tem 1. herein the position of a motor is'varied by these two ?eld windings are equally energized,
means of a control impedance, which cooper
the motor rotates in neither direction but upon
ates with a follow-up impedance positioned by one ?eld winding becoming more highly ener
0 the motor to cause the motor to run to a posi
gized than the other the motor rotates in one 10
tion corresponding to that of the control im
direction or the other depending upon which
pedance. One common form which such systems ?eld winding is more highly energized. The
have taken in the prior art is that in which rotors II and I5 are secured to a shaft l8. The
the control impedance and the rebalancing im
shaft I8 is connected through a reduction gear
15 pedance are connected in a normally balanced
train H to a shaft 20, which has secured thereto 15'
network which controls the energization of a bal-v a crank disc 2t which is connected through a
anced-relay, which relay in turn controls the en
crank arm 22 to the stem 23 of the valve H).
ergization of the motor. The dii?culty with such The valve is so designed that clockwise rotation
systems is that the ‘relay requires a certain of shaft 20 and consequently of crank disc 2|
20 ‘amount of , differential in order to successfully
will cause valve I ii to be moved towards open 20;
operate, and such di?erential materially reduces position and that counter-clockwise movement
the possible number of steps. >This di?iculty of crank disc 2| will cause the valve to move
can be overcome by an arrangement of vacuum towards closed position.
tubes or other space discharge ampli?ers, but
The energization of motor ?eld windings I 6
such devices are inherently expensive and of and I7 is controlled by two saturable core ampli
limited life so as to greatly increase the main
?ers 25 and 26. The saturable core ampli?er
tenance cost of the apparatus employing them.
25 consists of a rectangular frame having side
An object of. the present invention is to pro
legs 28 and 29 and cross legs 30 and 3|. The
vide a follow-up motor control system wherein frame is also provided with a shunt leg 32. Lo
30 the control of the motor in accordance with the
cated on the legs 30 and 3| are primary and sec
values of the control and follow-up impedances ondary windings 33 and 34. The primary wind 30
is accomplished by means of a saturable core ing .33 is connected through conductors 31, 38,
ampli?er.
I
v
_
39, and Ill] to two line wires 4! and 42 leading
A further object of the invention is to provide to a suitablesource of power (not shown). The
/
v25
35 such a follow-up system in which a reversible
motor having opposed windings is employed and
in which the relative energization of the two
values is controlled in accordance with the con
trol and follow-up impedances by a pair of sat
40. urable core ampli?ers.
v
A further object of the present invention is to
provide a follow-up system of the type set forth
in the previous objects in which the saturable
core ampli?ers are in the form. of saturable core
secondary 34 is connected by conductors 44, 45, 35
and 45 to ?eld winding IS. A saturating winding
68 is located on the shunt leg 32. The saturable
core ampli?er 26 is identical in structure to that
of core‘ 25 having side legs 49 and 50, outside
cross legs 5i and B2, and a shunt leg 53. This 40
ampli?er similarly has a primary winding 55 on
the cross leg 5i and a secondary winding 55
on the cross leg 52. The primary winding 55
is connected through conductors 38 and 40 to
4;; transformers.
line wiresdi and 152. The secondary winding
Other objects of the invention will be apparent 56 is connected through conductors 58;, 59, and 45
from a consideration of the accompanying speci , it to the ‘field winding ii. On the shunt core
?cation, claims and drawing.
53 a saturating winding Ed is located.
in the single figure of the drawing, the im~
The saturating windings it” and til are ener
r -, proved motor ‘control system‘ is shown in schei
gized by direct current. ‘A step-down trans 50
matic form. This system is shown in connection former $5 is employed for this purpose. This
. with a temperature control system although it is
to be understood that the invention is not so
limited.
7
-
Referring to the drawing, a valve is indicated
by the reference numeral‘ I ii. This valve is mere
ly illustrative of an object which may be vdriven
by the motor and is shown as controlling the
flow of steam through the steam line H lead-
ing to radiators or'other steam utilizing devices.
transformer comprises a line voltage primary $6
connected to the line wires 4! and 42 and a
center’ tapped low voltage secondary 67. The
center tap of secondary 6‘! is connected through
conductor 68 with a conductor'?s leading to one
terminal of saturating winding 48. The upper
terminal of secondary 6“! is connected through a
recti?er “H and conductors 12, 13, and 14, to’
‘ one terminal of saturating winding. 60.
The 60
2,130,090
2
lower terminal of secondary 81 is likewise con
nected to the same terminal of saturating wind
ing 80 through a recti?er 15 and conductors 18
and 14. The recti?ers 1i and 15 may be of
conductor 91, the protective resistance I03 and
conductor 14. The contact arm 81 is connected
through bimetallic element 88 and conductor 89
to conductors 18 and 10 which electrically con
any conventional type such as the common cop
, per oxide recti?ers.
The center tapped second
ary 61 in conjunction with the rectifiers H and
15 act to give full wave recti?cation in the con
ventional manner. The saturating windings 48
10 and 80 are connected together at their inner tern
minals by conductors 18 and 19. Thus when
the current is ?owing in one direction in sec
ondary 81, the following circuit is established to
the saturating windings 48 and 60: from the up
15 per terminal of secondary 81 through recti?er 1 I,
nect the saturating windings 48 and 60. In view
of the fact that potentiometer 88 is connected
parallel with the windings 48 and 80 and inas
much as the potentiometer 80 is connected in
parallel with potentiometer 85, it will be obvious
conductors 12, 13, and 14, saturating winding
80, conductors 19 and 18, saturating winding 48'
and conductors 88 and 88 to the center tap of
secondary 61. Current is prevented from how
20 ing in the other half by reason that such ?ow
could not be passed by recti?er 15. When the
current- is ?owlng in the opposite direction the
following circuit is established through saturat
ing windings 60 and 48: from the lower half of
26 secondary 81 through the recti?er 15, through
conductors 18 and 14, saturating winding 80,
conductors 19 and 18, saturating winding 48,
and conductors 88 and 88 to the center tap of
secondary 81. Thus, at all times, the current
30 ?ow through windings 60 and 48 is in the same
direction.
The relative energization of the two windings
48 and 80 is controlled by two potentlometers
85 and 88. The potentiometer 85 constitutes
85 the control potentiometer and is shown as com
prising a resistance 88 and a contact arm 81.
The arm 81 may be actuated in any desired
manner. For purposes of illustration, the arm
81 is shown in the drawing as actuated by a
bimetallic element 88 responsive to a tempera
ture change which it is desired to have control
the operation of the radiator Or other steam uti
lizing device receiving the steam through pipe
II.
The potentiometer 80 constitutes the follow
up potentiometer and is used to limit the move
ment of the motor to that called for by the con
trol impedance.
This potentiometer comprises
a resistance 9| and a contact arm 82. The con
tact arm 82 is secured to shaft 20 so as to be
50 movable therewith. Thus upon movement of the
shaft 20 in a direction to effect clockwise move
ment of crank disc 2|, the arm 82 is similarly
moved in a clockwise direction towards the left
of resistance 80. Upon an opposite rotation of
55 shaft 20, an opposite movement of contact arm
92 takes place.
The potentiometers 85 and 80 are connected
in parallel with each other. The left hand ends
of resistances 88 and SI are connected together
through conductors 85 and 88.
Similarly, the
right hand ends of these two resistances are
connected through conductors 81 and 88. The
contact arm 81 is connected to the contact arm
92 through bimetallic element 88 and conduc
The potentiometers 85 and 80
are not only connected in parallel with each
other but they are also connected in parallel
with the saturating windings 48 and 80. Thus
70 the left hand end of resistor 88 is connected to
the left hand terminal of saturating winding 48
65 tors 99 and I00.
through conductor 85, protective resistance I02,
and conductor 68. Similarly the right hand ter
minal resistor 88 is connected to the right hand
75 terminal of saturating winding 80 through the
that the two potentiometers 85 and 80 are both 10
connected in parallel with the windings 48 and
80. These two potentiometers thus act as volt
age dividers to determine the relative voltages
across saturating windings 48 and 60 and to
hence determine the relative current flow there 15
through. Thus, whenever the contact arm 81 is
moved to the left the voltage across saturating
winding 48 is decreased and that across saturat
ing winding 80 is increased. The result is that
the current through winding 48 becomes less
than that through winding 80. An opposite
movement of contact arm 81 causes an oppo
site unbalance in the energization of saturating
windings 48 and 80. The same effect upon the
relative energization of windings 48 and 80 is
‘
produced by a movement of contact arm 92.
Thus any unbalance in the energization of sat
urating windings 48 and 80 can be compensated
for by an opposite movement of contact arm
92 of rebalancing potentiometer 80.
The protective resistances I02 and I03 are for
the purpose of insuring against a short-circuit
ing of the transformer when the-contact arms
of the two potentiometers are in their opposite
extreme position. Thus the following circuit is
established when arm 81 is in its extreme left
position and arm 92 in its extreme right posi
tion: from the upper terminal of secondary 61
through recti?er ‘II, conductor 12, resistor I03,
conductor 88, contact arm 92, conductor I00, bi
metallic element 88, contact arm 81, conductor
85, resistor I02, and conductor 88 to the center
tap of secondary 81. Were it not for the pres
ence of resistors I02 and I03 this circuit would
short-circuit the transformer, which, of course,
would be undesirable.
The energization of the saturating windings
48 and 80 controls the amount of flux, produced
by primaries 33 and 55, which is by-passed
through the shunt legs 32 and 53. As a result,
the energization of the saturating windings 48
and 60 controls the output of secondaries 34 and
58. By operating the saturating windings 48 and
80 in such a manner that the shunt legs 32 and
53 are operated at-a proper portion of the satu
ration curve, a relatively small change in the
current flow through one of the saturating wind
ings will produce‘ quite a large change in the
output of the secondary. The result is that the
relatively large amount of power utilized by field
windings I8 and I1 can be controlled by a rela
tively small current through the saturating wind
ings 48 and 80.
Operation
The various elements of this system are shown
in the position assumed when the temperature to
which bimetallic element 88 is responsive is at
or about the desired value. The bimetallic ele
ment 88 is so disposed that a fall in temperature 70
causes the contact arm 81 to move to the right
and a rise in temperature causes the contact
arm to move to the left. Let it be assumed that
the temperature in the space begins to drop caus
ing a movement of contact arm 81 to the right. 75
3
This results, as previously explained, in saturating
windingv 60 becoming less highly energized than
saturating winding 48. This in turn results in
the output of secondary 56 becoming less than
that of secondary II. The result is that ?eld
winding it becomes more highly energized than
?eld winding ll. causing the motor to rotate in
one direction. The apparatus is so designed that
this direction is such that the shaft 20 is rotated 10 in a clockwise direction, causing clockwise rota
tion of crank disc 2|. This clockwise rotation of ‘
crank disc 2| causes valve M to be moved toward
open position admitting a greater amount of
steam to flow through pipe ll.
15
'
.
At the same time as the rotation of shaft 20
is eifecting a clockwise rotation of crank disc 2|,
it is also causing arm 92 to move in a clockwise
direction or towards the left of resistance M. It
will be noted that this‘ movement to the left is in
an opposite direction to the movement of contact
arm 81 which initiated the operation of the mo
tor. The result is that this movement of contact
arm 92 after it is carried su?lciently i'ar'results
in the saturating windings“ and 60 again being
equally energized and also in the secondary wind
ings 34 and 56 furnishing an equal output. Wind
ings i1 and It thus again become equally ener
gized so that the motor remains stationary. The
apparatus is so designed that the movement of
the motor that takes place before this rebaiance
occurs corresponds to the movement desired
for the change in position of contact arm 81
which initiated such‘movement.
'
‘
With the valve in a wider open position, more
steam is being admitted to the radiators or other
steam utilizing devices with the result that the
temperature to which bimetallic element '88 is
subjected begins to rise. This results in a move
ment of contact arm 81 to the left. The ‘effect
of this is to cause saturating winding 80 to be
come more highly energized than saturating
winding 48, as ‘previously explained. The result
of this is that the output of secondary 56 becomes
greater than that of secondary 34; consequently
?eld winding I'l becomes more highly energized
than ?eld winding i6, causing the motor to rotate
in a direction opposite to that previously de
scribed. The result is that the motor now rotates
in ‘a direction to cause crank disc 2| to be rotated
in a. counter-clockwise direction moving valve in
towards its closed position. At the same time the
contact arm 92 is moved towards the right in a
counter-clockwise direction. This movement of
contact arm 92 has an effect opposite to the
55 movement of contact arm 8'! to the left. The
result is that after this movement of contact
arm 92 has taken place by an amount correspond
ing to the de?ection of contact arm- 81 which
initiated the movement oi arm 81, the saturating
60 windings 48 and 60 will again be equally energized
to cause an equalization in the energization oi’
the motor ?eld windings i6 and it.
Thus it will be noted that at all times the posi~
tion of motor i3 and consequently of the object
65 controlled thereby corresponds to the position
assumed by the contact arm of the controlling
potentiometer. This system- moreover requires
no. differential beyond the small amount required
to effect reversal of the gear train.
Moreover
the transmission of the unbalance in the ener-
gization of the system consisting of the control
and rebalancing impedances, to the motor is ac
complished without the use of any moving parts
or with any parts of limited life.
75
,
While the invention has been described in con
nection with the use of potentiometers as the
control impedances, it will be obvious that other.
impedance elements can be substituted therefor.
It will also be obvious that various other changes
can be made in the apparatus shown within the
scope of the appended claims. It is to be under
stood that the speci?c form of the apparatus
shown is for purposes of illustration only.
I claim as my invention:
-
1. In a motor control system, an electrical mo
10
tor, a variable control impedance,‘ a variable fol
low-up impedance, means connecting said vari- ‘
able follow-up impedance to said motor and
operative to vary the value of said impedance in
accordance with the position of said motor, a 15
saturable core amplifier having a magnetic core
structure and output and saturating windings on
said core structure, means connecting said satu
rating winding with said control and follow-up
impedances to a source of power and operative to
energize said saturating winding in accordance
20'
'with the values of both said control impedance
and said follow-up impedance, and means con
trolled by said output winding for controlling the
energization of said motor.
,
2. In a motor control system, an electrical mo
tor, a variable control impedance, a variable
25
follow-up impedance, means connecting said
variable follow-up impedance to said motor and
operative to vary the value of said impedance in 30
accordance with the position of said motor, a
saturable core ampli?er having a magnetic core
structure and output and saturating windings on
said core structure, means connecting said satu-
rating winding with said control and follow-up
impedances to a source of power and operative 85
to energize said saturating winding in accordance
with the values of both said control impedance
and said follow-up impedance, and means includ
ing said output winding for energizing said mo
tor.
40
3. In a motor control system, an electrical
motor, a variable control impedance, 9. variable
follow-up impedance, means connecting said var
iable follow-up impedance to said motor and
operative to vary the value of said impedance in 45
accordance with the position of said motor, a
saturable core transformer having a magnetic
core structure comprising at least three legs one
of which constitutes a magnetic shunt with re
spect to the other legs, a saturating winding on 50'
said shunt leg and primary and secondary wind
ings on said other legs, means connecting said
primary winding to a source of power, means
connecting said saturating winding with said
control and follow-up impedances to a source of 55
power and operable to energize said saturating
winding in accordance with the values of bothv
said control impedance and said iollow~up im
pedance and means controlled by said secondary
winding for controlling the energization of said V60
motor.
4.. In a motor control system, an electrical
motor, a variable control impedance, a variable
follow-up impedance, means connecting said var
iable follow-up impedance to said motor and op
erative to vary the value of said impedance in
accordance with the position of said motor, a
saturable core transformer having a magnetic
, core structure comprising at least three legs, one
of which constitutes a magnetic shunt with re
70
spect to the other legs, a saturating winding on
said shunt leg and primary and secondary wind
ings on said other legs, means’ connecting said
primary winding to a source of power, means 76
4
2,186,695 ,
connecting said saturating winding with said
control and follow-up impedances to a source of
power and operable to energize said saturating
winding in accordance with the values of both
said contral impedance and said follow-up im
pedance and circuit connections between said
secondary and said motor.
5. In a motor control system, an electrical
motor, a variable control impedance, a variable
10 follow-up impedance, a saturable core ampli?er
havinga magnetic core structure and output and
saturating windings on said core structure, a
source of power, means to connect said saturat
ing winding and said control and follow-up im
15 pedances to said cource of power in parallel with
each other, whereby the energization of said
saturating winding is controlled by the com
bined values of said two impedances, means con
trolled by said output winding for controlling the
20 energization of said motor, and means'operative
ly connected with said motor for varying the
value of said follow-up impedance in a direction
opposite to the change in the value of the con
trol impedance which produced the movement of
25 the motor.
6. In a motor control system, an electrical
motor, a variable control impedance, a variable
follow-up impedance, a balanced impedance net
work comprising said impedances, a saturable
30 core ampli?er having a magnetic core structure
and output and saturating windings on said core
structure, a source‘ of power, means connecting
said saturating winding with said impedance net
work to said source of pewer in such a manner
35 that the energization of said saturating winding
is controlled by the amount of unbalance of said
network, means controlled by said output wind
1ing for controlling the energization of said motor,
and means operatively connected with said motor
for varying the value of said follow-up imped
ance in a direction and to an extent to rebalance
the impedance network.
'7. In a motor control system, a reversible elec~
trical motor having two energizing circuits, the
45 energization of one of which tends to cause the
motor to rotate in one direction and the ener
structure, a source of power, means connecting
said saturating winding with said impedance net
work to said source of power in such a manner
that the energization of said saturating winding
is controlled by the amount of unbalanceof said
network, means including said output winding
for controlling the energization of one of said
?eld winding energizing circuits to control the
extent and direction of rotation of said motor,
and means operatively connected with said motor
for varying the value of said follow-up impedance
in a direction and to an extent to rebalance the
impedance network.
9. In a motor control system, a reversible elec
16
trical motor having two energizing circuits, the
energization of one of which tends to cause the
motor to rotate in one direction and the ener
gization of the other of which tends to cause the
motor to rotate in the opposite direction, a vari 20
able control impedance, a variable follow-up im
pedance, a balanced impedance network com
prising said'impedances, a pair of saturable core
ampli?ers, each having a magnetic core structure
and output and saturating windings on said core
structure, a source of power, means connecting
said saturating windings with said impedance
network to said source of power in such a man
ner that when said network is balanced said sat
urating windings are equally energized and when 80
said network is unbalanced, one of said saturating
windings is more highly energized than the other,
depending upon the direction of unbalance,
means including one of said output windings for
controlling each of said motor energizing circuits,
and means operatively connected with said motor
for varying the value of said follow-up impedance
in a direction and to an extent to rebalance the
impedance network.
10. In a motor control system, a reversible
electrical motor having two opposed ?eld wind
ings which upon energization thereof tend to
cause rotation of the motor in opposite direc
tions, an energizing circuit for each of said ?eld
windings, a variable control impedance, a var
iable follow-up impedance, a balanced impedance
motor to rotate in the opposite direction, a vari
able control impedance, a variable follow-up im
network comprising said impedances, a pair of
saturable core ampli?ers, each having a magnetic
core structure and output and saturating wind
pedance, a balanced impedance network compris
ings on‘said core structure, a source of power, 50
' gization of the other of which tends to cause the
60 ing said impedances, a saturable core ampli?er
having a magnetic core structure and output and
saturating windings on said core structure, a
source of power, means connecting said saturat
55
output and saturating windings on said core
ing winding with said impedance network to said
source of power in such a manner that the ener
gization of said saturating winding is controlled
by the amount of unbalance of said network,
means including said output winding for con
60 trolling the energization of one of said energiz
ing circuits of said motor to control the extent
and direction of rotation of said motor, and
means operatively connected with said-motor ‘for
varying the value of said follow-up impedance in
65 a direction and to an extent to rebalance the
impedance network.
8. In a motor control system, a reversible elec
trical motor having two opposed ?eld windings
which upon energization thereof tend to cause
70 rotation of the motor in opposite directions, an
energizing circuit for each of said ?eld windings,
a variable control impedance, a variable follow
up impedance, a balanced impedance network
comprising said impedances, a saturable core
75 amplifier having a magnetic core structure and
means connecting said saturating windings with
said impedance network to said source of power
in such a manner that when said network is bal
anced said saturating windings are equally ener
gized and when said network is unbalanced, one 55
of said saturating windings is more highly ener
gized than the other, depending upon the di
rection of unbalance, means including one of said
output windings for controlling each of said ?eld
winding energizing circuits, and means operative
ly connected with said motor for varying the
value of said follow-up impedance in a direction
and to an extent to rebalance the impedance net
work.
11. In a motor control system, a reversible
electrical motor having two energizing circuits,
at
the energization of one of which tends to cause
the motor to rotate in one direction and the ener
gization of the other of which tends to cause the
motor to rotate in the opposie direction, a con 70
trol potentiometer, a follow-up potentiometer,
each of which comprises a relatively movable con
tact member and potentiometer, a pair of satur
able core ampli?ers, each having a magnetic core
structure and output and saturating windings on 75
2,186,695
said core structure, a source of power, means con
necting said saturating windings in series with
each other and in parallel with said control and
follow-up potentiometers to said source 01’ power
\ to form a normally balanced network in which
said saturating windings are equally energized,
means including one oi.’ said output windings for
controlling each of ‘said motor energizing circuits,
and means operatively connected with said motor
for varying the setting of said follow-up poten
tiometer in a direction and to an extent to re
balance the impedance network.
12. In a motor control system, a, reversible
electrical motor having two opposed ?eld wind
ings which upon energization thereof tend to
cause rotation of the motor in opposite directions,
an energizing circuit for each of said ?eld wind
ings, a control potentiometer, a follow-up poten
tiometer, each of which comprises a relatively
‘ movable contact member and potentiometer, a
pair of saturable core ampli?ers, each having a
magnetic core structure and output and saturat
ing windings on said core structure, a source of
power, means connecting said saturating windings
in series with each other and in parallel with
said control and follow-up potentiometers to said
source of power to vform a normally balanced net
work in which said saturating windings are
equally energized, means including one of said
output windings for controlling each of said ?eld
winding energizing circuits, and means opera
tivelyv connected with, said motor for varying the
setting of said follow-up potentiometer in a di
rection and to an extent to rebalance the im
pedance network.
13. In a motor control system, a reversible
electrical motor having two energizing circuits,
5
ings, a control potentiometer, a follow-up po
tentiometer, each or which comprises a relative
ly movable contact member and potentiometer,
a pair of saturable core transformers, each hav
ing a magnetic core structure comprising at
least three legs one of which constitutes a mag
netic shunt with respect to the other legs, a
saturating winding on said shunt leg and pri-_
mary and secondary windings on said other legs,
means connecting said primary windings to a 10.
'source of alternating current power, a source of
direct current power,. means connecting said
saturating windings in series with ‘each other
and in parallel with said control and follow-up
potentiometers to said direct current source of 15
power to form a normally balanced network in
which said saturating windings are equally en
ergized, means including one of said output
windings for controlling each of said ?eld wind
ing energizing circuits, and means operatively 20
connected with said motor for varying the set
ting of said ‘follow-up potentiometer in a direc
tion and to an extent to rebalance the impedance
network.
15. In a motor control system, an electrical 25
motor, a variable control impedance, condition
responsive means for adjusting the value of said
control impedance, a variable follow-up imped
ance, means connecting said variable follow-up
impedance to said motor and operative to vary 30
the value of said impedance in accordance with
the position of said motor, a saturable core am
pli?er having a magnetic core structure and
output and saturating windings on said core
structure, means connecting said saturating 35
winding with said control and follow-up imped~
ances to a source of power and operative to en
the energization of one of which tends to cause ergize said saturating winding in accordance
the motor to rotate in one direction and the en
with the values of both said control impedance
ergization‘ of the other of which tends to cause; and said follow-up impedance, and means con
the motor to rotate in the opposite direction, a trolled by said output winding for controlling 40
control potentiometer, a follow-up poteniom
the energization of said motor.
_
eter, each of which comprises a relatively movable
16. In a'motor control system, a reversible
contact memberv and potentiometer, a pair of electrical motor having two energizing circuits,
saturabie core transformers, each having a mag
the energization of one of which tends to cause
netic core structure comprising at least three the motor to rotate in one direction and the
legs one of which constitutes a magnetic shunt energization of the other of which tends to cause
with respect to the other legs, a saturating wind‘
the motor to rotate in the opposite direction,
ing on said shunt leg and primary and second
a control potentiometer, a follow-up potentiom
ary windings on said other legs, means connect
eter, each of which comprises a relatively mov-~
ing said primary windings to a source of alter
able contact member and'potentiometer, con 50
nating current power, a source 01' direct current dition responsive means for controlling the set
power, means connecting said saturating wind
ting of said control potentiometer, a pair of
ings in series with each other and in parallel with saturable core ampli?ers, each having a mag
said control and follow-up potentiometers to said netic core structure and output and saturating
direct current source of power to form a normally
balanced network in which said saturating wind
ings are equally energized, means including one
)1’ said secondary windings for controlling each
of said ?eld winding energizing circuits, and
means operatively connected with said motor for
varying the setting of said follow-up potentiom
:ter in a direction and to an extent to rebalance
zhe impedance network.
14. In a motor control system, a reversible
electrical motor having two opposed ?eld wind
ngs which upon energization thereof tend to
:ause rotation of the motor in opposite directions,
in energizing circuit for each of said ?eld wind
windings on said core structure, a source of power, 55
means connecting said saturating'windings in
series with each other and in parallel with said ’
control and follow-up potentiometers to said
source or power to form a normally balanced
network in which said saturating windings are
equally energized, means including one of said
output windings for controlling each ‘of said
motor energizing circuits, and means operative
ly connected with said motor for varying the set
ting of said follow-up potentiometer in a direc
tion and to an extent to rebalance the impedance
network.
GORDON F. LAING.
DISCLAIMER
2,136,695.—-Gord0n F. Lavlng, Minneapolis, Minn. MOTOR CONTROL SYSTEM.
Patent dated November 15, 1938. Disclaimer ?led February 20, 1940,
by the assignee, The Brown Instrument_ Company.
Hereb enters this disclaimer to claims 1, ‘2, 6, 7, and 15 in said speci?cation .
[ ?icial Gazette March 12, 1940.]
D I 5CLA l M ER
2,136,695.—G0¢¢Z0n F. Laing, Minneapolis, Minn. MOTOR CONTROL SYSTEM. Patent
dated November 15, 1938. Disclaimer ?led May 9, 1941, by the assignee,
The Brown Imtmment Company.
Hereby enters this disclaimer to claims 8, 9, and 10 in said speci?cation.
[O?icz'al Gazette Jzme10,1941.]
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