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Nov; 12, 1946.
.‘r. J, MESH
Filed June 19, 1944
. Frame: 12%;”
. BY
' ll’eteoiesi New; E2, 1946
ooN'rsoL APPARATUS FOR Arrows-mo
cosmos-r MQTORS -
vTheoilore J. Mesh, Eosthampton, Mess, essigoor
to Gilbert & Barker Manufacturing Company,
West Spring?eld, Mass, a. corporation of
Application June 19, 1944, Serial No. ssosso
3 Claims. ((71. 172-4374)
invention relates to the control of alter
noting current motors, such for example as the
synchronous motors used as timing motors for
various purposes.
The invention has for its object the provision
of means for stopping an alternating current
motel- lo. responseto any suitable control element
motor is stopped without the use of e switch or
relay in the supply circuit of the motor winding.
For this purpose, I provide for the rectiiicstlonv
of the alternating voltage wave, drawing a, pulsat
ing direct current through wires 3’ and 1l’ of such
magnitude as to produce :ior all precticol pur
poses the effect of a, short circuit across the mo
tor ?eld on the positive
cycles oi voltage.
Impedance 3 is included in the circuit, first, for
10 the purpose of limiting the current flow in the
recti?er during’ the above mentioned short cir
More psrlioularly, the invention has for an
cult periods, and, second, for the purpose of drop
object the provislonoi a rectifying means for
ping the voltage across motor iielrl 2 to a very
alternating current, which means is shunted
low value, when rectified cui'rent flows tli'l'ough
across ‘the motor Winding so that, when placed in
the wires ii’ and ii’. The resultant effect is the
action, is
short circuit the positive hali‘ cycles
elimination from the ?eld of she motor of the
of the voltage wave. The result is the elimination
and holding it in its stopped position, without
opening the switch by which the motor was
major portion» oi’ the positive hell‘ eycles of the
from the motor of 3,318 major part of the positive
voltage Wave and therootor stops instantly and
foali oyeles oi" the voltage Wave, whereby the mo
is held magnetically against movement as long as
tor will be stopped almost instantly and will be
llelel megnwicslly in its stopped position as long 20 recti?ed current ?ows‘v through the Wires 8' and
means remains in action.
A preferred form of recti?eetlo
Asses-‘iii to 2-, further object of the invention,
gridmontrolletl, seseous~?is the reetiiylos/ moons consists of a grid-controlled
represented at 3, anti in
~ .,
recti?er tube of the vacuum or gaseous type, such
means slog capable oi‘ actuation by a minute 25 the grid, 3 ~31 the oothode, ii the til quantity of electric power, as for example, that
derived fro time use of e phototu‘oe es the con
tsol elemelel.
These objects will loest lee understood as the
as the re ‘
deteilecl description proceeds and they will lee 39
pointeo". out in the appended claims,
condenser having a espeoity of 1 mid.
The invention will ‘so disclosezi'wlth reference
heater ll is connected to any suitable sou;"oe o
to the accompanying drawing, in which,
eleotrleity at low voltage, representeé, lay the wire
Figs. 1 to are diagrammeticel views showing
and soy for example six volts. One termin
the inventiop in several diilerent emweodlmeoizs.
oi the heater l l is also connected to wire
Referring to Fig. l of this drawing, 3 represents
also the terminal oi
"?elding grid 3
the rotor oi’ as alternating current mote? eml 2
the latter being eoonecteel MIG-?ssile
Wires 3
ll, which supply alternating current
le voltage and frequency, such for ex
issue-ll commeroiel supply
Q e’ycles. The motor rosy lie smell
” motor suols as is
ventiorislly representeo‘foy
the other terminal or" which the .
in timing
-e example of one such motor will lo-e
e patent "to Haydon Iio. 2,(lfl’=9,2l3l, ‘
The Haydon mosor is oi’ the
seoteel by 6 ans shows as interposed in wire is,
the circuit to the
‘tor is
impooonoe ll of any suitable Emil, pres“
stably :2, oomleoseir, for seasons Wliieli ‘will "later
prevents the tops l ifs-cm operating until toe {l3
slre sot-ion has taken place. When toe lee l is
actual-eel ‘by the closing of the control element 215,
o: allows current to ?ow from plots to ostl'lczle
‘out not in s severse oii‘eetion soil the motor
is stopped. as above
the comes; through
the ‘tube “5 and preierebly comes
or’ eotome
This invest-ion foes to do with the stopping of
mol 5/.‘ one
see to
to 52. very low value, are“ ~
ol’lesectez'lze?l in metal-ho so on the positive
be a resistor, condenser, or an inductance.
resistor may be most economical provided sum
of a timing motor at a predetermined position
drop through it under running conditions. The
use of a condenser to produce approximate reso
nance with the timing motor may provide an ac
tual increase in voltage at the motor over the
supply voltage. When the tube ‘I operates, the
motor current falls to a very low value because
With the use of a 10
condenser the power loss is nil. Where higher
motor currents are necessary, to secure locking
of the timing motor, as for example in those cases
where a spring has been wound up by the motor
and must be held against unwinding during the 15
motor-locking period, a resistance or inductance
may be used at 6 to provide for any value of cur
rent desired.
vention, it may be used to stop the control shaft
cient voltage is available to allow some loss or
the resonance is destroyed.
As an example of one practical use of their:
In Fig. 2, the invention has been shown in an
embodiment where the control element is a pho 20
totube 20, electrically connected across the plate
8 and grid 9 of tube 7. Here the tube heater
i I is shown as supplied from a six volt secondary
2| of a transformer, the primary 22 of which is
connected to the wires 3, 4 of the supply source. 25
A secondary 23 of the same transformer may
supply 6 to 12 volts alternating current as the
bias for tube ‘i. A condenser M‘may be con
after some operation has been effected and to
hold such shaft in such position as long as some
certain condition is satis?ed, as evidenced by
the control element. Then, when such condi
tion is no longer satis?ed, the motor may be
released and allowed to continue to turn to an
other position to e?’ect some other operation.
I claim:
1. The combination with a single phase alter
nating current motor having a main ?eld wind
ing and a shadedpole winding for starting pur
poses, of a circuit including said main ?eld
winding and adapted for connection to a supply
of alternating current, a, grid-controlled elec
tronic recti?er tube having its plate-cathode cir
cuit coupled to said ?rst-named circuit in par
allel with said main ?eld winding, an impedance
in said ?rst-named circuit in series with the
plate-cathode circuit of said tube and with said
main ?eld winding and of such value as to limit
the current ?ow through said plate-cathode cir
cuit to a safe value, and control means operable
by changing the grid potential of said tube to,
directly control its action and to place the same
into or out of action to respectively stop the
motor or enable it to operate.
nected in the bias circuit, as shown, and prefer
ably is so connected where the bias voltage is 30
2. The combination with a single phase alter
alternating. The other connections are as shown
nating current motor having a main ?eld wind
in Fig. 1. The operation is substantially the
ing and a shaded pole winding for starting pur
same as in Fig. 1, except that the presence of
poses, of a circuit including said main ?eld wind
light on the phototube 20 starts the operation of
ing and adapted for connection to a supply of
tube 1. The phototube provides an exceedingly 35 alternating current, an electronic recti?er tube
sensitive control element and causes operation
having its plate-cathode circuit coupled to said
of tube 1 by a minute amount of electrical power. »
?rst-named circuit in parallel with said main
In Fig. 3, the bias is obtained from a resistor
26 in series with the timing motor. The other
?eld winding, an impedance in said ?rst-named
circuit in series with the plate-cathode circuit
connections are substantially the same as in Fig. 40 of said tube and with said main ?eld winding
2. Because the timing motor-has inductance as
and of such value as to limit the *current ?ow
well as resistance, the voltage across it differs
through said plate-cathode circuit to a safe value,
slightly in phase from the bias voltage obtained
and means for changing the plate-cathode cir
across resistor 25. This is an undesirable condi
cuit from a non-conducting condition in which
tion and is overcome by applying the bias to the
said motor operates normally in the ?rst-named
grid of tube 1 through ‘the condenser 24. The
circuit to a conducting condition in which the
latter charges up because of the rectifying action
current ?ow through the main ?eld winding is
of the grid 9 and provides a direct current bias.
changed to uni-directional form to stop the mo
The condenser 24 has a capacity of .001 mfd.
tor and hold it in its stopped position.
more or less.
3. The combination with a single phase alter
In Fig; 4, bias is obtained from a voltage di
nating current motor having a main ?eld wind~
vider 26, connected acrossthe timing motor and
ing and a shaded pole winding for starting pur
consisting of resistors 21 and 28. The resistance
poses, of a circuit including said main ?eld wind
21 is low enough in value so as not to interfere
ing and adapted for connection to a supply of
appreciably with the action of tube 1. As here 55 alternating current, an electronic tube having
‘shown, the bias is in phase with the motor volt
age,‘ being obtained directly from it. Therefore,
the bias may be applied to the grid 9 of the tube
1 through a resistor 29, having a resistance of 5
megohms, more or less. A condenser may never
theless be used in place of the resistor 29 in this
circuit, if desired.
The different ?gures show diii'erent methods of
obtaining grid bias. The methods shown are not
exclusive and any other suitable ones may be
used as desired.
In all the ?gures of the drawings, there is the
same fundamental invention, namely, a rectify
its plate-cathode circuit coupled to the ?rst
named circuit in parallel with said main ?eld
winding, a capacitor in the ?rst named circuit in
series with said main ?eld winding and with the
60 plate-cathode circuit and of such value as to
produce resonance in the ?rst-named circuit at‘
the frequency of the supply, and control means
‘for changing the plate-cathode circuit from a
non-conducting condition, in which the motor
65 operates normally in the ?rst-named circuit, to
a conducting condition, whereby the action of the
tube destroys the resonance of the ?rst-named
circuit and converts the current through the main
ing means set into action by a control element of
?eld winding to uni-directional form to stop the
any suitable form and acting to change the nor 70 motor and hold it in its stopped position.
mal' alternating voltage wave across the motor to
one of unsymmetrical form and of such nature
as to prevent rotation of the motor.
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