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Патент USA US2133400

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Oct. 18, 1938.
Filed June 12, 1936
2 Sheets-Sheet l
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‘Oct. 18, .1938.
Filed June 12, 1936
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Patented Oct. 18, 1938
Estel C. Raney, Columbus, Ohio, assignor to
Ranco Incorporated, a corporation of Ohio
Application June 12, 1936, Serial No. 84,800
4 Claims. (Cl. 172-279)
My present invention relates to electrical con
appliance, for example, within the end bell of a
trol circuits and controllers therefor and more
A member 23 of pressed metal is posi
particularly to thermally controlled circuits and moior.
tioned on the base 2| by two integral lugs 26'
thermally operated switches for such circuits.
An object of my invention is to provide an elec
tric switch for the proteciion of motors. This
switch is thermally actuated and has a plurality
of heating coils disposed in proximity to the
thermal element for operating the swiich under
10 various conditions. The switch as designed, is
also sensitive to' overheated conditions of the
Another object is to provide a control circuit
including a thermal switch having two heater
15 elements for connection to, for example, a ca
pacitor-start type of motor. One heater is to be
in series with the running winding and the other
heater is to be in series with the starting wind
ing. The ?rst heater protects the motor against
20 current overloads, etc., while the second heater
protects against a stalled motor, or too heavy a
load on the motor. The switch is to be mounted
so that it is responsive to excessive motor tem
A still further object is to provide a tripping
device to be used in the construction of the switch
which includes a freely translatable latch or dog
for holding the switch in one position and a ther
mal release device associated with the latch;
30 which device is responsive to emergency con
ditions of excessive temperature for releasing
the latch to effect movement of the switch con
Other and further objects and advantages will
35 be apparent from the following description, ref
erence being had to the accompanying drawings
wherein preferred forms of embodiments of the
present invention are clearly shown.
In the drawings:
Fig. 1 is a side elevational view of the switch
with the contacts in closed position;
Fig. 2 is a view, partly in section, of the oppo
site side of the switch shown in Fig. l, with the
contacts in the open position;
Fig. 3 is a top view of the switch;
Fig. 4 is a sectional view on a larger scale, the
section being taken through the ratchet and
solder pot;
Fig. 5 is a view in elevation of the opposite side
50 or the ratchet shown in Fig. 4, and
Fig. 6 is a schematic wiring diagram of the
switch in a motor circuit.
Fig. 1 shows a thermally actuated switch 20.
A base 2| fabricated from a dielectricmaterial,
55 is used as‘ a means to attach the switch to an
which pass through the base and are clinched
over on the opposite side of the base 2|. The O!
member 23 is also provided with an integral
connecting lug 2'! for electrical connection. A
?xed contact 22 of suitable material, such as
silver, is mounted, as by riveting, on the support
member 23.
A movable member 25 is preferably fabricated
from spring material, such as full temper phos
phor bronze, which has desirable electrical con
ducting properties. A contact 24 is mounted,
as by riveting, to the movable member 25. The
member 25 is so formed as to normally tend to
separate the contacts.
The opposite end of the member 25 is con—
nected to the upper side of a U-shaped support
plate 28 by lugs 29 which are integral with the
plate 28 and pass through apertures 25’ in the
member 25. The lugs 29 are clinched over to in
sure a tight mechanical and electrical connec
tion between the support 28 and the member 25.
The opposite or lower leg of the U-shaped sup 25
port member 23 is fixed to the base 2| by integral
lugs 30 which pass through the base 2| and are
clinched over on the opposite side of the base 2|.
The member 28 also acts as the support for a
ratchet 3|, through its associated parts. A hol
low bearing post 32 forms the spindle for the
ratchet 3|. The post 32 is provided with an out
wardly extending ?ange 33 for connection to
the support 28. The ?ange 33 is attached to the
member 28 by integral lugs 34 clinched over to 35
form a tight engagement.
The ratchet 3| loosely embraces, and can be
freely rotatable on the post 32 when not held in
place by solder. A substantially circular plate
35 is pressed over, and siaked to, the post 32 to
prevent displacement of the ratchet 3|, with re
spect to the supporting post 32.
To prevent the ratchet 3| from normally being
rotatable, a low mel ing point solder “is used
to solder the ratchet 3| to the post 32. The
composition of this alloy 36 may be varied to
obtain any desired fusing point, for example,
200° F.
An engaging means, or dog 31, oi dielectric
material is employed to provide an actuating 50
link between the ratchet 3| and the member 25.
This dog‘ is freely translatable, in that no ?xed
bearing point is provided. The dog 31 has a
single'projection 33‘on one end thereof to en
gage with the teeth of theratchet 3|. The oppo 55
site end of the dog 31 is provided with two pro
jections 39 and 42, that form a substantially
is, if the solder is fused, it is also impossible to
close the switch 20.
forked end portion on the dog 31. The point 39
rests on the top of the member 25, as part of the
dog passes through an opening 43 in the mem
' In the present embodiment two heating coils
41 and 48 of any desired resistant material are
ber 25. The other projection 42 is so disposed
as to limit the upward movement of the dog 31
by engaging the underside of the member 23, as
shown in Fig. 2; the base 2| being cut away, to
10 form openings therethrough for the various ex
tending parts of the dog 31.
The dog 31 is drawn normally toward the base
2| by the tension of a spring 40 attached‘ at one
end through the hole 44 in the dog 31, and at
15 the other end to the reset guide member 4| which
is ?xed to the base'2l. The spring 40 is so dis
posed as to supply a horizontal component of
force tending to force the dog 31 toward the
ratchet 3| as well as provide the aforementioned
20 downward tension. A reset lever 45 of pressed
metal is pivotally attached to the dog 31 by a
disposed. within the bearing post 32, in heat
transferring relationship to the solder 36. One
end of each of the coils 41 and 48 is spot-welded
or otherwise attached to the support member 28.
These coils 41 and 48 supply radiant heat when
electrically energized by the passage of a current 10
When either, or both of these resistances supply
sufficient heat to bring the temperature of the
ratchet 3| and solder 36, to say, 200° F., the solder
36 will fuse and the ratchet 3| will be capable of 15
rotation on the post 32. In the set position of
the switch, spring 40 and dog 31 are constantly
supplying a downward pull, or turning torque,
on the ratchet 3|. Therefore, when the solder 36
fuses, the ratchet 3| rotates in a clockwise direc 20
tion and allows the dog 32 to come to the position
rivet pin 46. The lever 45 is split at its upper ' as in Fig. 2. It is apparent that by varying the
end to form a forked portion which engages resistance of the coils that the time period for
either side of the dog 31. The opposite end of operation may be altered to give any desired time
the lever 45 passes through an aperture -45’ in cycle.
The same effect may be obtained when ‘the
the guide member 4|. This construction‘is fol
lowed to assure alignment of the lever 45 and switch 20 is mounted on a motor. If the motor
associated parts. The device 20 may be suitably frame reaches a predetermined temperature of
secured to and on the inside of the end bell 60 say 200° F. due to a heavy load, a scraping arma
30 of the motor 54 and the lever 45 projects through ture, etc., the switch 20 will be heatedv conduc 30
an opening 6| of the bell 60 so as to be accessible tively by the motor frame, to fuse the solder 36,
from the exterior of the motor for resetting of which'will allow rotation of the ratchet 3| to
separate the contacts 22 and 24.
the tripping device.
The points 22 and 24 are incapable of being
It will be noted that when the projection 38
on the dog 31 is set in the teeth of ratchet 3|, I reset after operation untiLthe solder 36 has re 35
the opposite end or projection 39 is bearing down hardened. At this time, the reset lever 45 may be
pressed inwardly to engage the dog projection
on the spring contact member 25. In this posi
tion the spring 4|] is tending to draw the dog 31 38 with the ratchet 3|, thus re-closing the con
downwardly, which ?rmly presses the contacts 22 tacts 22 and 24.
This particular feature of construction is a
40 and 24 together to make an electrical ‘contact. safety factor, for it will be noted that even when
This position may be studied in Fig. 1.
When the projection 38 on the dog 31 has been the lever 45 is held in the set position, that the
displaced from engagement with the teeth of the contacts cannot be closed until the ratchet 3| is
fixed in position. This assures that the motor 54
ratchet 3|, the spring pulls the dog 31 downward
has cooled to a safe temperature before operation 45
position the dog 31 pivots on the pin 46 due to can be resumed.
Fig. 6 illustrates a schematic wiring diagram,
the tension of spring 40: and the projection 39
raises, to allow separation of the contacts 22 and showing one of the many circuits in which the
2,4. ' The other projection 42 of the forked end switch 28 may be advantageously utilized. A sin
gle phase AC motor is generally indicated at 54,
of dog 31, limits the upward movement by en
50 gaging the contact support member 23. This having a starting winding 53 and a running wind
ing 52. Current is supplied by the power lines
position of the device is illustrated in Fig. 2.
The projection 42 acts as a bearing point 50 and 5|; Line 5| is connected to both the
against the member 23 when the "dog 31 is being starting winding 53 and the running winding 52.
reset. As the reset lever 45 is pressed inwardly The other side of the line may be traced from wire 55
the dog 31 pivots on the projection 42 as the 50, to contacts 22 and 24 of switch 20, through
projection 38 is raised relative to the base. The ‘member 25, then splitting through heating coils
projection 38 contacts the teeth of the ratchet 3| 41 and 48. From the coil 48, the current goes
through wire 51 to the ?eld running winding 52,
but due to the translatable movement of the dog,
to complete the circuit. The current through
coil 41 traverses wire 55, condenser 56, centrifugal
lever 45 has reached its maximum inward move
switch 59, and wire 58 to complete the starting
ment. During this resetting operation the con
circuit. When both the running and starting
tacts 22 and 24 are not. in engagement as the dog winding circuits are energized, the motor starts
31 is pivoting on its projection 42. As soon as to rotate. As the motor 54 gains speed, the start
65 the pressure is released on the lever 45, spring ing winding 53 is no longer required and a usual
40 supplies a downward tension to engage pro
type of centrifugal switch 59 opens the circuit,
jection 38 with the teeth of ratchet 3| and also
to close the contacts, since projection 39 of the
dog 31 is now bearing down on the contact mem
through the winding 53 and the heating coil 41.
In this particular embodiment, the resistance
41, which is placed in series with the starting
70 ber 25.
From the foregoing it will be noted that it is
impossible to make contact through the device
winding, is so balanced with the resistance 48
that the two resistances 41 and 48 radiate suf?
cient heat to fuse the solder 36 in a predetermined
20 by pressing in on the lever 45. In a like man
if the ratchet 3| is not ?xed in position, that
time period. This will protect the winding if the
motor should not start, or should not gain sum
cient speed to cut the winding 53 out of the cir
The resistance 48 in series with the running
winding, is balanced to supply su?lcient heat to
keep the switch at a temperature of say, 150° F.
(normal running temperature), during normal
operation. Thus, if an overload current should
pass through the coil 48 to cause a rise in tem
perature, the coil is capable of quickly translating
10 a corresponding rise in temperature to the solder,
to operate the switch 20 and protect the ‘motor 54.
By maintaining the switch 20 at a temperature
slightly below the fusing point of the solder, it is
possible to eliminate operation of the switch, due
15 to transient overloads of any type that are not
harmful to the motor. In other words, the switch
20 will only operate on persistent overload condi
tions that would cause damage to the motor if
allowed to continue.
The motor temperature also aids in maintain
ing the switch at a given temperature, thus if
too heavy a load is impressed on the motor that
causes the- motor to gradually increase in tem-'
perature, the switch 20 will likewise increase in
temperature, due to conduction. This maintains
the switch at practically the same temperature as
the motor, so that operation, free from a time lag,
is obtained on overheating of the motor. Thus
the switch is sensitive to the temperature of the
30 motor, the temperature 01' the heater, or a com
bination of the two sources of heat, to act as a
protective device, under any type of overload
From the foregoing it will be noted that I have
35 provided a safety cut-out switch to completely
protect the motor against injury due to any type
of overload or open circuited windings. The re
sistance coils l1 and .8 may be varied in heating
effect to obtain any desired result. For example,
40 only one coil may be used or both coils may be in
the circuit continuously. In the latter case, the
resistance of the coils should be calculated so
that their combined heat output under normal
conditions is insufficient to fuse the solder, but
45 that a rise in temperature, in either coil due to
overload current, etc., or an abnormally high
temperature of the motor will supply the added
heat necessary to operate the device.
Another advantage of my construction lies in
50 the series circuit of the coils l1 and 48 with the
?eld windings. This design provides for deener
gization of the coils l1 and 48 when the protec
tive device 20 operates to break the circuit. This
eliminates burnouts of the heater coils and per
55 mits the switch to be reset any number of times in
contrast to a fuse type protector which requires
replacement after each operation.
My press/it switch provides complete protection
for any me
I- circuit such as the condenser start,
60 repulsion induction or split-phase types. It pre
vents burnouts due to an overheated motor, too
heavy a load on the motor, open circuited ?eld
windings, overload currents, or a stalled motor.
It also provides _a manual resetting device so that
the switch may be made operative after an emer
gency operation.
While the forms of embodiment of the present
invention as herein disclosed constitute preferred
forms, it is to be understood that other forms
might be adopted, all coming within the scope of
the claims which follow:
1. In combination with a motor having two
phase displaced windings, a circuit breaker in
the motor circuit, thermal responsive means for
causing opening of the circuit breaker, two heat
ing means in heat transfer relation with said
thermal responsive means, one of said heating
means being connected in the circuit of one of 15
the windings and the other of the said heating
means being connected in the circuit of the other
of the said windings, and means for opening one
of the winding circuits and deenergizing the heat- .
ing means therein in response to normal opera
tion of the motor.
2. In combination with a motor having a pair
of phase displaced windings, a circuit breaker in
the motor circuit, thermal responsive means for
causing opening of the circuit breaker, a pair of 25
heating means in heat transfer relation with said
thermal responsive means, one of said heating
means being energized in response to the ?ow or
current in one of the windings and the other of
the heating means being energized in response to 30
the flow of current in the other of the windings,
and means for causing deenergization of one of
the windings and heating means in response to
normal operation of the motor.
3. In combination with a motor having a run 35
ning winding and a‘ starting winding, a switch in
the motor circuit, thermal responsive means for
opening the switch when the thermal responsive
means is heated to a predetermined temperature,
heating means adapted to be energized in re
sponse to' energization of the running winding in
heat transfer relation to the thermal responsive
means, a second heating means in heat transfer
ring relation to the thermal responsive means and
adapted to be energized in response to energiza
tion of the starting winding, and means respon
sive to a normal running condition of the motor
for deenergizing the starting winding and the
‘last mentioned heating means.
4. In a motor, a power circuit, a pair of motor
windings, having circuits connected in parallel 60
in the power circuit, a switch in the power cir
cuit, a temperature responsive means for operat
ing the switch to open the power circuit, a pair
of heater elements in heat transferring relation 55
to the temperature responsive means, one of said
heater elements being connected in one of the
motor winding circuits, and the other of the
heater coils being connected in the other of the
motor winding circuits, and means for opening 00
one of the motor winding circuits in response to
normal running conditions of the motor.
mm C. RANEY.
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