July 9, 1957 W. B.

McLEAN 2,798,995
ELECTRIC MOTOR
Filed Jan. 2, 1955 2 Sheets-Sheet l

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INVENTOR.
WILLIAM B. MC LEAN
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July 9, 1957 W. B. MCLEAN 2,798,995
ELECTRIC MOTOR
Filed Jan. 21, 1955 2. Sheets-Sheet 2

411/444444
NSNS

8 INVENTOR.
A 727, Ay, WILLIAM B. M LEAN
BY-642.6%. ,
26, 24
ATToRNEYs
 2,798,995
United States Patent Office 1.
Patented July 9, 1957
2
on post 14 which is secured by bolts 16 to base plate 18.
Post 14, bolts 16, and plate 18 as well as the remainder
2,798,995 of the metal parts illustrated (with later-mentioned ex
ceptions) are made from suitable non-magnetic materials
ELECTRIC MOTOR such as aluminum. Rotor 10 consists of a permanent mag
William B. McLean, China Lake, Calif., assignor to the net 20, made in a preferred example of "Alnico V,” an
United States of America as represented by the Secre alloy consisting of 8% aluminum, 14% nickel, 24% co
tary of the Navy balt, 3% copper, and the remainder iron, and a modified
Cassegrainian telescope reflector 22. The north and south.
Application January 21, 1955, Serial No. 483,451 10 poles of magnet 20 are located on a line which intersects
5 Claims. (Ci. 318-254) the center of bearing 12 as seen in Fig. 2, and the poles
are near the circumference of rotor 0. Motor drive coils
(Granted under Title 35, U. S. Code (1952), sec. 266) 24, 26, 28, 30 are circumferentially disposed about magnet
20 and within a plastic housing 32 which is permanently
5 secured to base plate 18. Coils 24, 26, 28, 30 are equal
The invention described herein may be manufactured in size and in the number of turns comprising each coil.
and used by or for the Government of the United States The motor drive coils are circumferentially and equiangu
of America for governmental purposes without the pay larly spaced with respect to the center of bearing 12.
ment of any royalties thereon or therefor. Magnetic switches 34, 34a, which are single pole double
This invention relates to electric motors, and in par 20 throw switches, are mounted on member 38 which in turn
ticular to an electric motor which has a permanently mag is secured to the outer side of base plate 18 by screws 40.
netized rotor. Switches 34, 34a are, in a preferred example, cemented
The motor of this invention is particularly adapted to to member 38 and are so mounted on member 38 with
drive the rotor of a gyro stabilized telescope of a target respect to the longitudinal axis 42 of post 14 that lines
seeker. In my copending application No. 377,899, filed 25 through the center of the switches and axis 42 substantially
February 19, 1953, and entitled Target Seeking Gyroscope, determine a right angle. It should also be noted that the
there is disclosed one form of such a gyro stabilized tele center of bearing 12 lies on axis 42 and that the switches
scope which has a permanent magnet mounted on the
rotor of the gyroscope. Interaction between the magnetic 34,rotation 34a lie in a plane which is parallel to the normal plane
field of the permanent magnet and the magnet field of a 30 of Details of rotor. 10, or at right angles to axis 42.
of magnetic switch 34 are illustrated in Figs.
periodically energized circumferential coil is used to con 4 and 5. Cylindrical base 44 is made of a suitable insulat
trol precession of the rotor of the gyroscope,
In the motor constituting this invention, the permanently therein. The armatureplastic
ing material such as
48 of
and has a slot 46 formed
the switch comprises a per
magnetized rotor is driven by the interaction between the manent magnet 49 which is encased in tube 50 made of a
magnetic field of its permanent magnet and magnetic fields 35 nonmagnetic conductor such as brass. Armature 48 is
induced in sequentially energized coils which are circum pivotally mounted within slot 46. The bearings for arma
ferentially located about the rotor. The energization of ture 48 consists of two pins 52, 54 which are located in
these coils is controlled by two single pole double throw openings formed in base 44 and engage armature 48.
Switches each of which has a permanently magnetized ar Pins 52, 54 which are shown as substantially radial with
mature actuated by the magnetic field of the permanent 40 respect to the axis 42 as well as to the axis of armature
magnet of the gyro rotor. 48, are held in place by set screws 56, 58. Electrical con
It is, therefore, an object of this invention to provide an tacts 60, 62 are also mounted in base 44 and extend into
improved motor for driving the rotor of a gyroscope. slot 46 so that tube 50 can contact one or the other of
It is a further object of this invention to provide a simple them. An electrical circuit extends from set screw 53,
self starting motor for a gyroscope which has a perma 45 pin 52, to tube 50 of armature 48. Switch 34a is identical
nently magnetized rotor. in construction with switch 34.
It is still a further object of this invention to provide a In order to explain the operation of the invention, at
simple self starting motor for a gyroscope which will drive tention is directed to the schematic diagram given in Fig. 6.
the rotor in a predetermined direction. When rotor 10 is just past the relative position illustrated
Another object of this invention is to provide a self 50 in Fig. 6, switch 34 is closer to the north pole of the mag
starting motor for the rotor of a gyroscope which exerts net 20 of rotor 0 than to its south pole. The south pole
Substantially no restraining torques on the rotor. of magnet 49 of switch 34 is attracted to the north pole of
Other objects and many of the attendant advantages of magnet 26 which pivots armature 48 so that armature 43
this invention will be readily appreciated as the same be engages contact 62. A D. C. circuit thus exists from
come better understood by reference to the following de 55 terminal 64, which is adapted to be connected to a suitable
tailed description when considered in connection with the Source of D. C. potential, through coil 24, contact 62, and
accompanying drawing wherein: armature 48 to ground. Coil 24 is wound and connected
Fig. 1 is a section taken on line 1-1 of Fig. 2, in the circuit so that direct current flowing from terminal
Fig. 2 is a section taken on line 2-2 of Fig. 1, 64 to ground creates a magnetic field that repels the north
Fig. 3 is a side elevation taken in the direction of arrow 60 pole of magnet 20 and attracts its south pole.
3 by the device illustrated in Fig. 1, At the same time, Switch 34a is closer to the south pole
Fig. 4 is an enlarged partial section taken on lines 4-4 of magnet 20 so that the north pole of magnet 49a is at
of Fig. 3, tracted toward the south pole of magnet 20. Armature
Fig. 5 is a section taken on lines 5-5 of Fig. 4, and
Fig. 6 is a schematic diagram for illustrating the theory 65 48a is pivoted so that it engages contact 60a, and a D. C.
circuit exists from terminal 64 through coil 30, contact
of operation of the motor. - 69a and armature 48a to ground. Coil 3) is wound and
Referring now to the drawing, wherein like reference connected in the circuit so that when a direct current flows
characters designate like or corresponding parts through through coil 30 from terminal 64 to ground a magnetic field
out the several views, there is shown in Figs. 1 and 2 rotor is established which attracts the south pole of magnet 20
f6 of a gyroscope which is mounted on a central universal 70 and repels the north pole. As a result, a torque is de
ball bearing 2 so as to have two degrees of angular free veloped which tends to rotate rotor 10 in the direction in
don) in addition to being rotatable, Bearing 12 is mounted dicated by arrow 64' in Fig, 6,
 ": 2,798,995
3 -
When rotori0 has turned slightly more than 90 from not be precessed as much as 20° from its initial position
its initial position as seen in Fig. 6 and in the direction of after being uncaged. When the motor is used to drive
arrow 64, there is no change in the position of armature the rotor after it has been uncaged, this Small angle of
48 of switch 34. Coil 24 remains energized and the mag precession will not adversely affect the operation of the
netic field produced by the direct current in coil 24, con rotor nor will it cause the motor to develop excessive
tinues to repel the north pole and attract the south pole of restraining torques which would cause the rotor to precess
. . magnet 20. However, the north pole of magnet 20 is now in an undesirable manner.
nearer to switch.34a than its south pole, so that the south Obviously many modifications and variations of the
pole of magnet 49a is attracted to the north pole of mag present
net. 20, causing armature 48a to engage, contact-62a. . . A 0. teachings.invention are possible in the light of the above
It is, therefore, to be understood that within
D. C. circuit then exists from terminal 64 to ground the scope of the appended claims the invention may be
through coil 26. Coi126 is wound and connected in the practiced otherwise than as specifically described.
circuit so that when direct current flows from terminal. 64
through it to ground, the north-pole of magnet 20 will be
What is claimed is:
repelled. 15
1. A motor-comprising a bar-type magnetized armature
When rotor 10 has turned through an angle slightly symmetrically journalled for rotation about an axis per
pendicular to the longitudinal axis of said magnet, a set of
greater than 180 from the position illustrated in Fig. 6, four stator coils positioned circumferentially and sym
the south pole of magnet:20 will be nearer switch 34 than metrically about said axis of rotation and adapted, when
the north pole of magnet 20. The north pole of magnet . . energized by a D. C. source, to produce torque action upon
49 will be attracted to the southpole of magnet. 20. causing 20.
said armature about said axis of rotation, a pair of double
armature. 48 to pivot and engage contact 60. Thus, coil . . throw.switches adapted and positioned to operate in quad
28 is energized with current flowing from terminal 64 rature sequence and to each provide a complete cycle of
through coil 28 to ground. Coil 28 is wound and con , switch operations by. magnetic influence of said armature
nected in the circuit so that the magnetic field it produces
when energized as described repels, the north pole of mag 25'..during a complete revolution thereof, and circuit means
net 20. There is no change in the position of armature establishing connections between the switches and stator
43a so that coil 26 remains energized. coils and for-sequential energization of said coils by said
When rotor 10 has turned through an angle slightly :. . rotation
switch operation and D. C. source to provide continuous
of the armature about said axis of rotation.
greater than 270 from the position illustrated in Fig. 6, ... 2. A gyroscopic apparatus comprising, in combination,
there is no change in the position of switch 34 so that coil 30 a rotors' mounted for continuous angular displacement
28 remains energized. However, the south pole of mag about an: axis of rotation, said rotor including a bar-type
net 20 is now nearer to magnet 49a of switch 34a than
the north pole of magnet. 20. Switch 34a has changed "... its magnetized armature-mounted symmetrically thereon with
longitudinal axis perpendicular to said axis of rotation,
position so that a circuit exists from terminal 64 through - a set of four stator coils positioned circumferentially and
coil 30 to ground. Coil 30 is wound and connected in symmetrically about said axis of rotation and adapted,
the circuit so that when direct current flows from terminal when energized by a D. C. source, to produce torque ac
64 to ground through coil 30, a magnetic field is produced '...tion upon said armature and rotor about said axis of rota
which repels the north pole of magnet 20. tion, a pair of double-throw switches adapted and posi
From the foregoing it can be seen that the four motor tioned to operate in-quadrature sequence and to each pro
drive coils 24, 26, 28, 30 are in effect sucessively ener 40 vide a complete cycle of switch operation by magnetic
gized, at least one coil being energized at any instant, and
two adjacent coils being energized except for the short influence
thereof,
of said armature during a complete revolution
and circuit means establishing connections be
period of time when one of the switches is changing posi tween the switches: and stator coils and for sequential
tion. Because of the arrangement of switches 34, 34a, energization of said coils by said switch operation and
one or the other changes position every time rotor i0 D. C. source: to provide continuous rotation of the arma
turns through 90. Member 38 carrying the switches is ture and rotor about said axis of rotation.
oriented with respect to the motor drive coils to obtain the
proper phase relationship between the current flow through a 3.rotor A gyroscopic apparatus comprising, in combination,
mounted for- continuous angular displacement
the motor drive coils and the position of rotor 10 in order about an axis of rotation which is itself pivoted for two
for the motor to operate most efficiently. degrees of precessional freedom with limited angular
Rotor is provided in actual practice with caging means, 50 displacement about a center lying on said axis, said rotor
which are not illustrated, so that its axis of rotation ini including a bar-type magnetized armature mounted sym
tially is substantially coincident with axis 42. Irrespective metrically thereon with its longitudinal axis perpendicu
of the initial position of rotor 16, one or the other of the lar to said axis of rotation, a set of four stator coils posi
magnetic switches. 34, 34a will be closer to one of the tioned circumferentially and symmetrically about a nor
poles of magnet 20 than the other so that an electrical
circuit will exist through at least one of the motor drive energized by of
mal position said axis of rotation and adapted, when
a D. C. source, to produce torque action
coils whenever a suitable source of D. C. potential is ap
plied to terminal 64; thus the motor is self starting. By : aupon pair
said armature and rotor about said axis of rotation,
of double-throw switches adapted and positioned
the proper arrangement of the switches and coils, the motor 60 to operate in quadrature sequence and to each provide a
can be arranged to drive the rotor in a predetermined di complete cycle of switch operation by magnetic influence
rection.
The motor constituting this invention can be used in of said armature during a complete revolution thereof,
several different ways. In one example, it is used merely and circuit means establishing connections between the
switches and stator coils and for sequential energization
to start the rotor and see that it initially is turning in a 65 of said coils by said switch operation and D. C. source
given direction and thereafter the rotor may be driven to provide continuous rotation of the armature and rotor
by other means. In another example, the electric motor about said axis of rotation.
constituting this invention is used to bring the rotor up to 4. A motor comprising an armature having two poles
maximum speed and then is stopped with the rotor there and symmetrically journaled to define a motor drive axis,
after being allowed to coast. - Also, the motor can be used four drive coils spaced substantially uniformly about
to continuously drive. the rotor. The maximum-angular 70 said axis, a pair of double-throw switches positioned at
velocity of the rotor is determined by the inertia of the substantially uniform distance from said axis and in a
armature 48. The maximum langular velocity can be plane...
selected to correspond to the velocity it is desired to ro iswitches: operating-byperpendicular
substantially to said axis, said
magnetic influence of said arma
tate the rotor of the gyroscope. Rotor. 10.will normally 75 sture...to; provide, during a -complete revolution of said
 2,798,995
6
arnature, a complete cycle of double-throw switch action, axis, said switches operating by magnetic influence of
said switches being further positioned in quadrature rela said armature to provide, during a complete revolution
tionship about said axis whereby to operate in quadrature of said armature, a complete cycle of double-throw switch
sequence, and circuit means connecting said drive coils S action, said switches being further positioned in quadra
to a D. C. source through said switches for sequential ture relationship about said axis whereby to operate in
energization of said drive coils such that, initially, two quadrature sequence, and circuit means connecting said
adjacent drive coils are energized to exert a starting drive coils to said switches for sequential energization
torque of predetermined direction upon said armature to of said drive coils such that, initially, two adjacent drive
coils are energized to exert a starting torque of prede
impart rotation thereto about said axis, and thereafter 10 termined direction upon said armature to impart rota
the four drive coils are energized in a continuing sequence tion thereto about said axis, and thereafter the four drive
during rotation of said armature to maintain rotation in coils are energized in a continuing sequence during rota
said predetermined direction.
5. A gyroscope motor comprising an armature hav tion of said armature to maintain rotation in said prede
ing two poles and symmetrically journaled to define a 5 termined direction.
motor drive axis which is subject to limited angular dis References Cited in the file of this patent
placement relative to a center lying on said axis, four UNITED STATES PATENTS
drive coils spaced substantially uniformly about a normal
position of said axis, a pair of double-throw switches 2,538,216 Stehlik ----------------- Jan. 16, 1951
positioned at uniform distance from, and in a plane 2,558,540 Clos ------------------ June 26, 1951
substantially perpendicular to, the normal position of said 20