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Патент USA US2405066

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July 30, 1946.
‘
J, D_ Em
2,405,066
- POSITION REPRODUCING MECHANISM
Filed March 28, 1942
2 Sheets—$heet l
INVENTOR
JAMES D.TEAR
BY
If)?‘
ATTORNEY
3%, 194-5,
.3, 5;), TEAR
POSITION REPRODUCING MECHANISM
Filed March 28, 1942
2 Sheets-Sheet 2
mm
llllllllll?llllllll'l I I]
INVENTOR
JA M Es D. TEAR
Z0214 ,a/QM/I- '
1-!TTORNE Y
Patented July 30, 1946
2,405,066
UNITED STATES PATENT OFFICE
2,405,066
POSITION REPRODUCING l‘JIECHANISM
James D. Tear, Great Neck, N. Y., assignor to
Ford Instrument Company, 1110., Long Island
City, N. Y., a corporation of New York
Application March 28, 1942, Serial No. 436,685
9 Claims.
1
(Cl. 172-239)
2
The invention relates to mechanisms for repro
ducing position and particularly to such mech
tio of movement thereto that the coarse receiver
bears to the ?ne receiver. The two contacts are
anisms of the follow-up type in which the trans
spaced a predetermined distance when the relief
connection is in its biased position, and the dis
mission system operates a control member for a
power unit termed a servo-motor.
The invention is applicable with self syn
chronous transmissions in which the torque of
the receivers is zero when they are in synchro
nism with their transmitters, and which employ
dual transmissions of different speed ratios, the
units of positional value transmitted by the low
speed transmitters being relatively large or
coarse, and those transmitted by the high speed
transmitters being relatively small or ?ne.
A characteristic of embodiments of the inven
tion is the fact that there is but a single control
member for the amplifying power unit, and that
this control member is operated by a drive which
is selectively controlled by the ?ne and coarse re
ceivers depending upon the positional error, that
is, the extent to which the driving or motion re
ceiving member fails to synchronize or agree in
tance is decreased in proportion as the relief con
nection departs from its biased position until the
contacts engage whereupon the auxiliary motor
is energized and assumes control of the control
member. This occurs before the condition is
reached where the relief connection would jump
to a false position and thus throw the control
member further out of phase relation with the
?ne receiver rotor.
The invention also contemplates suitable
clutching means in the connection with the aux
iliary motor which is engaged only When the
coarse receiver is in charge and thus relieves the
?ne receiver of the load of the armature so long
as the ?ne receiver is in charge.
This invention is adapted for actuating a ser
vo-motor control of the type in which the veloc
ity at which the power driven response ap
proaches the velocity of the transmitted move
position with the original or motion transmitting
member; and it is with the proper transfer and
ment, such as a signal, is limited to some func
maintenance of this selective control that the in 25 tion of the discrepancy between the received sig
vention is more especially concerned.
nal and the power driven response. Such a type
In such follow-up systems the power unit op
of control is desirable when synchronizing the
erates reversely upon the control member to shut.
response with the signal as in starting up the sys
oiT the power when the transmitted movement is
tem or whenever the response may depart from
completely reproduced. The movement of the ' the signal for any reason, such as a shift of the
control member is usually limited in both direc
receivers to a di?erent pair of transmitters.
tions and a relief connection or yieldable coupling
Other objects and advantages of the invention
in the drive from a receiver to the control mem
will appear from the following description of the
ber frees the receiver rotor from limitation in
embodiment of the invention shown in the ac
synchronizing with its transmitter. The con
companying drawings.
struction of this relief connection is such that
Fig. 1 shows diagrammatically an embodiment
the drive for the control member is biased to a
of the invention used in connection with a sim
positional relation with the receiver rotor and is
ple form of servo-motor control.
self synchronous or self-correcting within the
Fig. 2 shows a modi?ed form of servo-motor
range of a limited error beyond which it tends to 40 control in which the servo-motor is controlled so
increase the error in order to return to biased re
that the velocity at which the error in response
lation, by returning in the wrong direction.
is removed is a function of the error.
In accordance with this invention an auxiliary
power unit arranged under the control of the
coarse receiver is connected to supplement the
drive to the control member and to cause the
coarse receiver to assume charge of the control
member for the servo-motor as long as the error
The two speed transmission shown is of the
type disclosed for example in the patent to Hew
lett and Willard No. 1,559,524. The two trans
mitters l and 2 are geared together by gearing 3
such that motion applied by a motion transmit
ting member 4 will move the rotor of transmitter
exceeds the limited amount. The auxiliary pow
l at a high speed relative to that of the rotor of
er unit may be an electric motor the energizing 60 transmitter 2, say 36:1. The rotors of the re
circuit of which includes a pair of contacts one
ceivers 5 and 6 will have the same ratio of move
of which is moved with the coarse receiver and
ment.
the other of which is moved in the same path by
The rotor of the ?ne receiver 5 is connected
the drive for the servo-motor control member
by a shaft 1 to one side of a centralized relief
operated by the ?ne receiver, and at the same re. 55 connection or yieldable drive coupling 8 the other
2,405,066
3
4
34 is engaged, and that the torque of motor 36
side of which is connected by shaft 9, bevel gears
in and shaft ii to one side of a control differ
is applied on shaft 9.
ential l2. Speci?cally the coupling 3 is of the
construction shown in the patent to Poitras and
Tear N0. 2,13%,488.
going description. The yieldable drive couplings
The operation will be apparent from the fore
have on one side a cam and on the other a spring
pressed follower, the cam surface tapering in both
A reversible power motor l3, shown as an elec
directions from a high spot to a diametrically op~
posite low spot The spring causes the follower to
tric motor, is connected by shaft it, bevel gears
55 and shaft it to a second side of control differ
ential l2, the shaft l4 also being connected to
drive the load which it is desired to position in ac
seek the low spot. If the two sides get out of an
10 gular agreement so far that the cam rides over
cordance with the transmitted positional value.
the high spot the spring will return the follower
to the low spot by a continuation of movement in
the same direction and thus further increase the
error. In other words the drive is self correcting
able electric contact, which is energized by'a source
of power it and is alternatively connected to ‘the 15 only up to substantially 180° of error.
It is this fact that determines the spacing of
motor l3 by the leads of reversing contacts iii
the contacts 26 and 27. The arms 25 and 23 are
and 2s. The motor is is connected to the other
so set that the contact 24 is midway between con
side of the power source it by a lead 2|.
tacts 26 and 27 when the couplings are in their
It will be understood that as the rotor of the
receiver motor 5 is turned in response to the 20 biased position. Let it be assumed that power mo
tor i3 lags in its following and hence that the in
transmitted value, the contact ll will be moved
put of shaft I i into the differential I2 is not-coun
to close one or the other of the motor circuits and
teracted su?iciently fast by the input of shaft [6.
the power motor will rotate in a direction to posi
The contact ill will be rotated against either con
tion the load in accordance with the movement
of the motion transmitting member, and at the 25 tact id or 2b and as the error accumulates the
cam follower of coupling 8 will ride up the cam
same time the movement of shaft it will be trans
surface against the spring tension. Arm 28 sim
mitted to the differential it through the shaft
ilarly lags but in the reduced ratio, and the spac
i6 and neutralize the input to the differential,
ing of contacts 26 and 21 is so determined that
thereby opening the contact ll and stopping the
30 the appropriate one is engaged by the contact 24
motor 63.
just before the cam follower reaches thehig'h spot
The shaft 22 of coarse receiver 6 is connected
of the cam and hence before the coupling 8 can
through a yieldable coupling 23, similar to cou
jump ahead. The motor 36 is thereby energized,
pling 8, to rotate an insulated contact 2" on the
and the clutch being at the same time closed, the
end of radial arm 25. The contact 263 cooperates
with two insulated contacts 26 and El located on 35 motor torque is applied to the shaft 9 in a direc
tion to prevent the shaft from jumping ahead
opposite sides of the contact 24 and carried by
if the error increases and the follower passes over
the arm 23 which is mounted for rotation co
the high spot, and thus from increasing the effect
axially with the arm ‘.25. The arm 28 is directly
of the error.
connected to and is rotated by a gear 29 which is
Assuming the ratio of 36:1, one complete rota
driven through reduction gearing 3%] by a gear 3! 4.0
tion of the ?ne receiver or 360° of movement of
on shaft 9. The ratio of the gearing '33 is the
the member ll represents one-thirty-sixth of a
same as that of the gearing?, and hence the ro
complete rotation of the coarse receiver, or 10°
tation of the arm 28 relative to the shaft 9 is the
of movement of the arm 25. If the follow-up is
same as the ratio of rotation of the coarse trans
accurate the contacts 2% and 2'! will move along in
mitter unit relative to that of the ?ne transmit
synchronism with the contact 24 and keep it cen
ter unit.
tralized. However as the follow-up gets'out of
The shaft 9 carries a gear 32 which is geared
synchronism the coupling 58 begins to yield and
with one member 33 of a clutch unit 34. The
the drive of arm 28 gets correspondingly out of
other member 35 of the clutch unit is rotatably
connected to the armature of a reversible electric 60 step but at the reduced ratio. When the shaft
fl is 180° out of phase with the shaft 1, the arm 28
motor 36 by vgears 3i and shaft 38 on which the
is 5° out of phase with the arm 25. The maxi
member 35 is slidably mounted. The clutch mem
mum spacing of the contacts 23 and 21 is such
ber 33 is freely mounted on shaft 33 but is re
that just before that condition is reached the
strained against axial movement. Surrounding
shaft 3% is a stationary coil 39 and a ?eld frame 65 contact 24 engages, but, of course, the spacing
may be vless.
iii) of magnetic material. The clutch member 35
Conditions arise in use, particularly at the start
and shaft
are also of magnetic material and
of the operation, When the disparity between the
therefore when the coil 39 is energized the mem
positions of the motion transmitting and receiv
ber
will be pulled into engagement with a fric
tion surface, such as cork, on the member 33. 60 ing members will greatly exceed the range within
which the system is self correcting and which
Thus rotation of motor 35 will be communicated
require perhaps one or more complete turns of
through the clutch unit 315 to the shaft i3.
the ?ne receiver and a partial turn of the coarse
Three slip rings Ill, 62 and 63 on the shaft of
receiver to be fed into the control differential to
arm 23 are electrically connected respectively
with the center contact 24 driven by coarse re (i5 bring the follower'member into positional agree
ment with the transmitter member. It will be
ceiver t, and the two contacts 26 and 2'! driven
The third member of differential l2 actuates a di
rectional control member H, in this case a mov
by the shaft 9. Brushes contacting these slip
rings connect with the windings of motor 36
through leads
£55 and lit respectively. The
seen that although both the coarse and ?ne re~
ceivers are turning over, the coarse receiver is in
controlof the input to the differential l2, until
common lead 416 includes a source of power All 70 the contacts 24, 26 and 21 are satis?ed and open
and the coil 39 in series relation. It is apparent,
therefore, that as the contact 21% touches either
of contacts 23 and 2? the energizing circuit of
motor 36 is closed to produce a torque in one
direction or the other, and at the same time clutch 75
the circuit of the motor 36, but when the torque
of this auxiliary motorbecomes zero the shaftt
returns to'control of the ?ne receiver and the
follow-up motor is thereby sensitively controlled
to bring the follower member into exact syn
2,405,066
6
chronism, when the contacts I1, [9 and 20 are
satis?ed and the circuit of the motor 13 is opened.
In the servo-motor control shown in Fig. 2 the
- 1. A position reproducing mechanism compris
ing coarse and ?ne receivers of a self synchronous
contacts I9 and 20 are mounted on an arm 48
transmission system having a predetermined ratio
extending from a shaft 49 mounted in axial align
ment with the shaft on which the contact I? is
mounted. The shaft 49 carries a pinion 55 mesh
I claim:
of relative movement, a servo-motor, an ener
sizing circuit for the servo-motor including a mov
able contact, operating means for the movable
ing with a gear 5| on a shaft 52, The shaft 52
contact having a yieldable drive connection with
has secured to it an arm 53 to the end of which
and biased to a de?nite angular relation to the
centralizing springs 54 are attached. The shaft 10 ?ne receiver, a response connection from the
49 also carries’ a gear 55 which-meshes with a
servo-motor operative to neutralize the effect of
pinion 56 connected to drive a drag disc 57. The
the operating means upon the movable contact.
drag disc is shown as running in a chamber 58
a pair of movable contactable elements one
?lled with a liquid such as oil, but any form of
coupled to be driven by the coarse receiver and
drag device may be employed. The gear 55 carries
the other coupled to be driven in the same direc
a pin 59 adapted to engage a ?xed pin 60 and
tion by the contact operating means at the said
thereby limit the rotation of gear 55 and arm 48
predetermined ratio of movement thereto, the
carrying the contacts [9 and 20.
said elements being positioned a de?nite distance
With this form, of servo-motor control the cen
out of contact when the contact operating means
tralizing springs 54 will maintain the contacts
is in its biased relation to the ?ne receiver, and
l9 and 20 in a ?xed position during normal oper
means actuated by the engagement of the con
ation, that is, when the response represented by
tactable elements for supplementing the bias of
shaft [6 remains synchronized with the signal
the operating means.
represented by shaft II. If for any reason the
2. A position reproducing mechanism compris
response, represented by shaft It, does not agree
ing coarse and ?ne receivers of a self synchronous
with the signal represented by shaft II, the
transmission system having a predetermined
contact I‘! will displace the contacts [9 and 29
ratio of relative movement, a servo-motor, an
against the centralizing effect of the springs 54.
energizing circuit for the servo-motor including
This displacement may correspond to several
a movable contact, operating means for the mov
turns of the ?ne receiver motor 5 and is only 30 able contact, drive means yieldably connecting
limited by the stop pins 59 and 60. It will be seen
the contact operating means and the ?ne receiver
that the receiver motor 5 will remain in direct
and including a cam and a spring pressed follower
control of the drive 9 even though the response
biasing the parts to a de?nite angular relation
may differ from the signal by an amount repre
and operative to reverse the angular direction of
sented by several turns of receiver 5. It will also
be seen that the contact 24 will remain centered
between the contacts 25 and 21 during the ac
cumulation of this difference.
When the stop pins 59 and 60 come into contact
and stop the movement of contacts is and 29,
contact I‘! is also stopped and shaft 9 is forced
from its biased position relative to receiver 5
until contact 24 engages either contact 26 or 2"!
and the motor 35 comes into action as explained
in connection with Fig. 1.
When contacts l9 and 29 are thus displaced
bias when a limited departure from biased rela~
tion is exceeded, a response connection from the
servo-motor operative to neutralize the effect of
the operating means upon the movable contact.
a pair of movable contactable elements one cou
pled to be driven by the coarse receiver and the
other coupled to be driven in the same direction
by the contact operating means at the said pre
determined ratio of movement thereto, the said
elements being positioned a de?nite distance out
of contact when the contact operating means is in
its biased relation to the ?ne receiver, and means
actuated by the engagement of the contactable
elements for applying a predominant bias to the
operating means to prevent reversal.
from their central position the centralizing force
resulting from the springs 54 is substantially
proportional to the displacement.
As the re
sponse from motor l3 causes contact I‘! to move 50
3. A position reproducing mechanism compris
ing coarse and ?ne receivers of a self synchronous
from its engaging contact the springs 54 will move
transmission system having a predetermined ra
the engaging contact toward the central posi
tio of relative movement, a servo-motor, ener
tion. This motion will be opposed by the drag
gizing means for the servo-motor including a
disc 51 so that the rate at which the contacts
movable control member, operating means in
return to their central position is proportional
cluding a relief cam operatively connecting the
to their displacement. The motor I3 can there
rotor of the ?ne receiver with the control mem
fore remove the error only at the rate at which
ber, response means‘ operated by the servo-motor
the contacts return to their central position.
for neutralizing the action of the ?ne receiver
During the return of the contacts l9 and 25 to
their central position the shaft carrying contact (50 rotor upon the control member, a pair of con
tacts movable in a common path, one coupled to
I‘! is limited to the same rate. This shaft repre
be driven by the coarse receiver and the other
sents the error between the response from servo
coupled to be driven in the same direction by
motor i 3 and the receiver 5 and therefore the
the control member operating means at the said
error can only be removed at a rate which is de
predetermined ratio of movement thereto, the
termined as a function of the displacement, that
said pair of contacts being spaced a de?nite dis
is, of the error.
tance when the ?ne receiver rotor and the control
This speed control in attaining synchronism is
member
operating means are in synchronism, the
the subject matter of my copending application
relief cam permittingdeparture from synchro
Serial No. 432,237.
nism su?'iciently to allow the pair of contacts to
It is obvious that the principle exempli?ed in
engage, an auxiliary motor, an energizing cir
the illustrated embodiments of the invention may
cuit for the auxiliary motor including the pair
be otherwise applied without departing from the
scope of the invention as de?ned in the follow—_
ing claims.
75
of contacts, and means operatively connecting the
auxiliary motor to the control member operating.
means.
'
2,405,066
8
bias of the operating means when the relative
4:. A position reproducing mechanism compris
movement of the control elements exceeds a pre
ing coarse and ?ne receivers of a self synchronous
determined amount.
transmission system having a predetermined ra
7. A position reproducing mechanism com
tio of relative movement, a servo-motor, energiz
prising coarse and ?ne receivers of a self syn
Cr
ing means for the servo-motor including a mov
chronous transmission system having a prede
able control member, operating means including
termined ratio of relative movement, a servo
motor, energizing means for the servo-motor in
a relief cam operatively connecting the rotor of
the fine receiver with the, control member, re
sponse means operated by the servo-motor ior
neutralizing :le action of the ?ne receiver rotor
cluding two relatively movable, cooperative con
trol members, operating means for one of the
movable control members having a yieldable drive
upon the control member, a pair of contacts
connection with and biased to a de?nite angular
relation to the ?ne receiver, a response connec
movable in a common path, one coupled to be
driven by the coarse receiver and the other
tion from the servo-motor to the said movable
control member, the second movable control
member being adjustably mounted, means bias
coupled to be driven in the same direction by the
control member operating means at the said pres
determined ratio of movement thereto, the said
pair of contacts being spaced a de?nite distance
ing the adjustable control member toward a
position to e?ect positional agreement between
when the ?ne receiver rotor and the control mem
the operating means and the servo-motor, means
to retard the return movement of the biased
member from a displaced position, the control
ber operating means are in synchronism, the re
lief cam permitting departure from synchronism
sufficiently to allow the pair of contacts to en~
members coacting to displace the adjustable
gage, an auxiliary motor, an energizing circuit
member an amount proportional to the error
for the auxiliary motor including the pair of:
contacts, means operatively connecting the au::—
in positional agreement between the operating
means and the servo-motor, a pair of relatively
iliary motor to the control member operating
movable control elements coupled to be relatively
moved by the coarse receiver and the control
means, a normally open clutch in the said con~
necting means, and means controlled by the said
pair of contacts for closing the clutch,
member operating means at the said predeter
mined ratio of relative movement, and means
actuated by the pair of control elements for sup
plementing the bias of the operating means when
the relative movement of the control elements
exceeds a predetermined amount.
8. A position reproducing mechanism com
prising coarse and ?ne receivers of a self syn
chronous transmission system having a prede
5. A position reproducing mechanism compris
ing coarse and fine receivers of a self synchro
nous transmission system having a predeter
mined ratio of relative movement, a' servo-motor,
energizing means for the servo-motor including
a movable control member, operating means for
the control member, a relief drive connecting
the control member operating means and the
termined ratio of relative movement, a servo—
rotor of the ?ne receiver and including a cam
motor, means for energizing the servo-motor in
and a spring pressed follower biasing the said
cluding primary and secondary contacts, oper
operating means and rotor to a de?nite angular
ating means having a yieldable drive connection
relationship at which the movable control mem» 40
with and biased to a de?nite angular relation to
her is synchronized with the said rotor and yield
the ?ne receiver, a response connection from the
able to permit departure from synchronism, re
servo-motor coacting with the operating means to
sponse means operated by the servo-r ,o'tor for
position the primary contact, a pair of movable
neutralizing the action of the ?ne receiver rotor
contactable elements one coupled to be driven
upon the control member, a pair of contacts mov
by the coarse receiver and the other coupled to
able in a common path, one coupled to be driv “
be driven in the same direction by the operating
by the coarse receiver and the other coupled to
means at the said predetermined ratio of move
be driven in the same direction by the control
ment thereto, the said elements being positioned
member operating means at the said predeter
a de?nite distance out of contact when the oper
mined ratio of movement thereto, the said pair 5 U ating means is in its biased relation to the ?ne
of contacts being spaced a de?nite distance W11 .3.
receiver, means actuated by the engagement of
the ?ne receiver rotor and the control mern 1
the
contactable elements for supplementing the
operating means are in synchronism, where
bias of the operating means, the secondary con
the contacts may engage as the yieldable p
tact being yieldably biased to open contact rela
permit departure from synchronism, an auxil
tion to the primary contact when the operating
motor, an energizing circuit for the an“ iary 1r
tor including the pair of contacts, and m
means, and the response connection are in posi
.
operatively connecting the auxiliary motor to the
contact operating means.
6. A position reproducing mechanism com
prising coarse and ?ne receivers of a self-syn
chronous transmission system having a predee
termined ratio of relative movement, a servo—
motor, energizing means for the servo-motor in
cluding a movable control member, operating
means for the movable control member having a
yieldable drive connection with and biased to a
de?nite angular relation to the ?ne receiver and
having a response connection from the servo
motor, a pair of relatively movable control ele
ments coupled to be relatively moved by the
coarse receiver and the control member operat
ing means at the said predetermined ratio of
relative movement, and means actuated by the
pair of control elements for supplementing the
tional agreement, the two contacts coacting to
effect a displacement of the secondary contact
60
an amount proportional to an error in said posi
tional agreement, and means to retard the re
turn of the secondary contact to the biased posi~
tion when displaced therefrom.
9. A position reproducing mechanism com
prising coarse and ?ne receivers of a self syn
chronous transmission system having a prede
termined ratio of relative movement, control op
erating means having a yieldable drive connec
tion with and biased to a de?nite angular rela
tion to the ?ne receiver, a, pair of relatively mov
able control elements coupled to be relatively
moved by the coarse receiver and the control op
erating means at the said predetermined ratio of
relative movement, means actuated by the pair
of control elements for supplementing the bias
2,405,066
of the control operating means when the relative
movement of the control elements exceeds a
predetermined amount, a servo-motor operably
connected to drive a response shaft, means
di?erentially connecting the control operating
means and the response shaft to actuate a con
trol for the servo-motor to bring the response
shaft into angular agreement with the control
10
operating means, and means associated with the
control for the servo-motor effective to cause
the servo-motor to bring the response shaft into
angular agreement with the control operating
means at a rate which is a function of the lack
of angular agreement of the response shaft with
the control operating means.
JAMES D. TEAR.
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