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Патент USA US2050332

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Aug. 11, 1936.
O R H_ JORDAN
'-
2,050,332
HEATING DEVICE
Filed Feb. 21, 1954
WITNESSES:
8”
W
Y woo
2 Sheets-Sheet 2
INVENTOR
I
Richard H Jordan.
Patented Aug. 11, 1936
2,350,332
UNITED STATS
YET
FFlCE
2,050,332
HEATING DEVICE
Richard H. Jordan, Spring?eld, Mass, assignor
to Westinghouse Electric & Manufacturing
Company, East Pittsburgh, Pa., a corporation
of Pennsylvania
Application February 21, 1934, Serial No. 712,349
6 Claims.
My invention relates to electrical heating de
vices and it has particular relation to electric
hand driers and other comparable devices which
produce a stream of heated air for direction
against objects which are to be dried.
In order to eliminate the necessity for towels
(Cl. 219—39)
taken .on lines III-III, IV—-IV and V-V of Figs.
1 and 2;
Fig. 6 is a plan view of the improved heating
unit which forms a part of the drier shown in
the preceding ?gures;
Fig. 7 is a view in side elevation of the heater
in business of?ce, public, and other washrooms,
of Fig. 6;
there have, in recent years, been developed me
chanical driers which typically comprise an elec
tric heater through which a motor-driven blower
discharges air for direction against the hands and
resistance-wire supports which forms a part of
10
the heater of Figs. 6 and 7.
face of a user. All devices of. this character with
support spacers incorporated in this heater;
which I am familiar have, however, been subject
to certain limitations and disadvantages, espe
15 cially when considered for residence installation,
and it is to the overcoming of such disadvantages
and limitations that the present invention is di
rected.
'One object of my invention is to provide an
20 electrical hand drier which is compact in design
and artistic in appearance.
Another object of my invention is to provide a
construction for drying devices .of the type under
consideration which facilitates an adjustment of
25 the direction of discharge of. the heated air.
A further object is to protect the heating unit
of the drier from damage upon failure of the
blower to operate.
Another object of my invention is to improve
30 the starting characteristics of driving motors of
the single-phase induction type.
A still further object is to protect the drier con
trol switch from damage in the event of excess
movement of the operating foot treadle.
Another object of my invention is to provide a
construction for hand-driers which facilitates a
concealment of the ?oor-fastening means.
An additional object of my invention is to im
prove the construction of electrical heating units
40 adapted for use in hand driers and other com
parable heating devices.
My invention itself, together with additional
objects and advantages thereof, will best be un
derstood through the following description of a
45 speci?c embodiment when taken in conjunction
with the accompanying drawings in which:
Figure 1 is a view in side elevation of the im
proved hand drier of my invention, a portion of
50 the exterior casing being cut away to indicate
the internal construction;
Fig. 2 is a view in end elevation of the device
of Fig. 1, a portion of the exterior casing also
being cut away;
55. Figs. 3, 4 and 5 are section views respectively
Fig. 8 is a side elevational view of one of. the
Fig. 9 is a view in end elevation of one of the
Fig. 10 is a view in side elevation of the heater
protecting centrifugal switch which is responsive
15
to the speed of the blower shaft;
Fig. 11 is a view in end elevation of the rotat
able composite-ring assemblage which forms a
part of. the centrifugal switch of Fig. 10;
Fig. 12 is a View in end elevation of the sta
tionary frame and contact carriage comprised by 20
this switch; and,
Fig. 13 is a simpli?ed or schematic diagram
showing one preferred manner in which the .elec
trical devices comprised by the improved hand
drier of my invention are interconnected with 25
each other for energization from a power circuit.
Referring to the drawings, and particularly to
Figs. 1 and 2 thereof, the hand drier of my inven
tion there shown comprises an air blower Ill
which is supported in an angle-iron frame com 30
prising four upright members l2, suitably braced
and interconnected by cross members certain of
which are shown at M and It. Underneath the
blower it, which may be of. any one‘ of a number
of well-known types now commercially available,
is mounted an electric motor 20 which drives the
blower by means of an endless belt 22 intercon
necting a pulley 2! carried by the motor with a
cooperating pulley 24 attached to one end of the
blower shaft H2. This particular arrangement
of the blower and its driving motor, when of the
form and relative proportions shown, has the
advantage of reducing the thickness of the com
plete drier assemblage and, hence, in the interest
of compactness of design, is the one which I pre 45
fer to utilize.
In the cylindrical air-discharge passage 28 of
the blower is positioned an electrical heating unit,
the construction of which is more completely
50
shown in Figs. 6 to 9, inclusive. In Figs. 1 and 2
only the protruding top portion 36 of this heater
is represented. Operation of the drier is con
trolled by means of a switch 80, mounted on the
angle iron frame work.
While, as shown, the 55,
2
2,050,332
switch is actuated by means of a foot treadle 83,
it will be understood that, if desired, other ac
tuating means may be used to effect its operation.
Surrounding the draft-producing and air
heating equipment just described is a suitable
casing which, as shown, comprises two identical
halves 36, preferably constructed of sheet metal,
which, as may best be seen by an inspection of
Fig. 5, are interconnected by means of. metal
spacer strips 38 and 39. It will be observed that
each edge of the spacing strips 38 and 39 inter
?ts between a ?anged portion 48 of the casing
member 36 and a soldered-on portion 139 which
completes a groove of the proper dimensions and
15 character. This exterior casing completely covers
and hence conceals the draft-producing mecha
nism and in addition forms, above a partition
member to, a pressure chamber or compartment
into which the heated air is blown. From this
20 chamber the warm air is discharged for drying.
purposes through a suitable opening in the top
which it escapes through the outlet ?xture 42 for
direction against the objects to be dried.
The discharge ?xture 1%2 is adjustably mounted
to permit the direction of the stream of warm
air to be changed by the manipulation of handles
58 which protrude from the pressure chamber
sides. When, as illustrated in the drawings, the
opening occupies the central or mid-position in its
range of adjustment, the heated air will be dis
charged in a vertical direction from the top of 10
the casing,
The discharge ?xture [l2 comprises a frame 64
which is supported, through a pair of sheet metal
strips 8%, from a shaft 5%, to the protruding ends
of which shaft are attached the adjusting han
15
dles 58. These supporting strips may be secured
to the shaft by any suitable means such as the
pairs of cooperating nuts 62, and have ?xed to
their upper ends, as by welding, the ?xture frame
6-2. This frame carries a plurality of round bar 20
members 65 arranged in parallel or grille-like
fashion over the discharge opening.
thereof.
In order that the semi-circular path of ad?
It is found preferable to completely assemble
the exterior casing before ?tting the same down justment' travel of the warm-air outlet ?xture
25 over the blower and driving motor unit to which 1'52 will be closed with the exception of the'area,
the two casing halves 36 may be secured by of the ?xture, a thin and ?exible metal strip Till,
shown in Figs. 3 and 4, through an opening in
means of screws fill which ?t into threaded holes
45 suitably positioned in certain members of the which the frame 64 of the ?xture protrudes, is
slidably mounted in appropriate slots formed
frame of the blower units. To cover the heads
by the raised edges l2 of the opposing top por
30 of these attaching screws lid, and to otherwise im
tions of the casing halves 36 and specially ?anged
prove the external appearance of the drier, metal
metal
strips “it which are welded thereto. It will
strips 52 are vertically positioned in the manner
shown along the centers of the two sides of the be understood that if desired the single strip with
casing, they being. ?tted in a notch 53 at their the opening cut therein may be replaced by two
separate strips which are respectively attached to
35 lower ends and held at their upper ends by the
the two ‘ends of the ?xture frame 64. As the po
washer or bearing members all of the outlet ?x
ture adjuster. To hold the casing halves together sition of the outlet ?xture 42 is changed, the
during the assembly operation and to further ?exible strips ‘it will follow in the grooves provided therefor in the semi-circular top section
strengthen the complete assemblage at the up
of the casing, and at all times maintain the 40?
per portion thereof, cross braces lit are provided.
To isolate any vibration which may originate in pressure chamber closed with the exception of the
?xture itself.
the hand drier, rubber supports 86 secured to the outlet
Manipulation of either of the handles 58 thus
feet of the blower mechanism framework in the‘
causes the outlet ?xture [12 to change its posi
manner shown are provided to effect a resilient
45 contact with the floor or other surface upon
which the drier may be set. These supports
86 protrude a short distance below the lower edge
of the exterior casing 36, and thereby separate it
fromdirect contact with the supporting surface.
50
While any suitable means for effecting the re
quired air-tight partition between the upper and
lower compartments of the blower may be uti—'
lized, I have found that a layer of felt represented
at lit, the contour of which is such that it inti
55 mately contacts the sides of the surrounding cas
ing, in the manner best indicated by Fig. 5, is ex
ceedingly effective. To secure this layer of felt
in place, a thin plate of sheet metal iii may be
clamped down over the top of the felt by means
60 of screws "13 which secure it to the structural
members of the blower supporting framework
therebeneath.
In order that air for discharge through the
blower into the upper or pressure compartment
65 may be admitted into the space occupied by the
blower structure Ml, which draws it through the
open spaces in the spoked end bracket l M of the
blower, suitable openings HQ may be made in
each end of the lower portion of the casing in
.the manner shown. During operation of the
drier, the air from the room is drawn in through
these openings llD, discharged by the blower ill,
through the heating coils 95 (Fig. 5) positioned
in the outlet 28 of the blower, into the pressure
75 chamber in the upper portion of the casing from
tion in the semi-circular space between the up
per portions-of the co-operating casing halves
35S and thereby changes the direction of air dis
charge. To limit the travel or restrict the range
of this adjustment, stop members, in the form
of angle pieces El welded to the side of the cas 50
ing, are adapted to make contact with one of,
the strips (if! when either limit of travel is reached.
To prevent chattering of the ends of the flexible
strip iii which protrude below the rim l2 of the
casing halves, the welded on strips 13 may be ex 55
tended down to an intermediate elevation as
shown in Fig. 4.
It will be apparent that through the use of this
improved construction, adjustment in the posi
tion of the outlet ?xture 42 may be made with but
little effort on the part of the operator, since the
friction to movement of the ?xture and the ?ex
ible sealing strip attached thereto may be re
duced to a low value.
>
Energizing current for the blower driving
motor and the air heater is derived through a
connection. with the lighting or other power sup
ply circuit established by means of a ?exible cord
l5 terminating in a plug connection 76 which
may be inserted into a wall or other outlet ?xture.
As shown, the cord enters the drier casing through
a hole in the bottom of metal strip 38, in which
hole an insulatitng bushing ‘ll is placed.
The switching device at, utilized to control the
operation of the drier, is illustrated as being of
60 “
3
2,050,332
the so-called “momentary contact” type, it com
pleting an energizing circuit only as long as an
operating lever 8| thereof, which is maintained
in the upward position shown by resilient means
incorporated in the switch construction, is con
tinuously depressed. Depression of this lever is
effected by means of the foot treadle 83, which
protrudes to the outside of the casing through a
suitable slot 84 cut in the lower endvof the spacer
10 strip 39. Connection between the treadle and
switch lever is established by means of a spring
85, which is of su?icient rigidity to transmit
switch-actuating movements. The elongating
characteristic of the spring allows, without in
jury to any of the associated mechanism, the
treadle to be further depressed after the switch
arm 8| has reached its limit of downward travel.
While it will be understood that any suitable
air heating unit may be utilized in the hand drier
of my invention, the unit which I prefer to utilize
because of economy of construction and ease of
replacement, is illustrated by Figs. 6 to 9, inclu
sive, which heater has already been referred to in
the explanations of the showings of the com
plete drier assemblage. One desirable feature of
such a heater is that the heating conductors posi
tioned in the passage through which the air to
be heated is blown shall be uniformly distributed
throughout that passage and shall not unduly ob
30 struct the flow of air therethrough. Thus, it is
preferable to position the coils 99 of heating wire
in some manner such as is indicated by the show
ing of Fig. 6 which is a top or plan View of the
improved heating unit of my invention which, as
before explained, is positioned in the cylindrical
outlet passage 28 of the blower Ill.
In the construction of this heating unit, a cylin
drical shell 39 is formed from sheet metal, a ?at
strip of which is ?rst cut to the desired dimensions
40 and then bent into the circular contour of the
cylinder. In this position the cooperating or
overlapping edges of the sheet are spot welded or
otherwise secured to each other, this junction
being indicated in Fig. 7 by the area of overlap
92. In the original ?at sheet are also cut two
parallel oblique slots 93 and 94, each of which
in the assembled cylindrical shell 30 are spiral in
form, as also indicated in Fig. 7.
The cylindrical shell having been assembled,
porcelain heating wire supports 96, a side view of
one of which is shown in Fig. 8, are then inserted
in the spiral slots 93 and 94, they being spaced
from each other by means of suitably slotted
spacers 98 constructed of sheet metal, an end
view of one of which spacers is shown in Fig. 9.
At the bottom of slot 94 and at the top of slot 93
are positioned terminal bolts 97 which secure the
two ends of the coil of heater wire 96, which coil
is progressively threaded among the specially
GO spaced supports 96 in the manner indicated in
Fig. 6. Energizing-circuit connections with the
coil are made through the terminals 91 by means
of conductors 95, which are threaded through a
porcelain bushing 99 carried by a top ring mem
ber I08 which surrounds and is secured to the
upper portion of the ‘cylindrical shell 30 by an
attachment effected by means of bolts I63, to a
pair of shell ears I62.
For greater ease in assembly of the heater unit,
the coil of heater wire 9i} may be threaded through
the insulator supports 96 before their insertion
into the slots in the cylindrical shell, in which
case, this preparatory threading operation may
readily be accomplished by arranging the insu
, lators which are to go in each of the two spiral
slots in parallel lines on a ?at surface, which
lines are spaced substantially by the diameter of
the shell, and then threading the coil of heater
Wire in zig-zag fashion progressively through
these supports. When spacedly placed in the two
opposing slots, the resulting diversi?cation of the
individual branches of the heater coil length
shown in Fig. 6 will obtain, and a stream of air
in being blown through the cylindrical shell 30
will be uniformly and effectively heated without 1O
receiving undue physical obstruction.
In installing the heater unit in the cylindrical
discharge opening 28 of the blower III, it may be
secured to the top rim thereof by means of screws
I06 which are accommodated by the holes III‘! 15
in the heater rim I00.
In order to obtain the desired effectiveness of
a heater adapted to warm air which is'blown
rapidly therethrough, it is necessary to operate
the resistance wire or conductor at such a high 20
current that should for any reason the draft of
air be discontinued, the conductor will attain
such excessively high temperatures as to burn out.
Consequently, in a device of the type under con
sideration, should for any reason the blower dis;
continue its operation or fail to start upon ener
gization of the heater unit, the unit will be burned
out. To protect against damage from this cause
is one objective of the present invention.
In effecting such protection, I dispose in the
energizing circuit of the heating unit, a centrif
ugal switch which is responsive to the speed of
the blower shaft. This switch, which is generally
indicated in the showing of Fig. l at III), requires
that the blower I6 be brought up to speed before 35
the heater can be energized and also serves to
interrupt the heater circuit as soon as the blower
speed decreases to a predetermined low value. ~
In the improved hand drier of my invention, ‘I
prefer to mount this switch directly on the shaft
II 2 of the blower inside of the end bracket H4
in a manner shown in greater detail by Fig. 10.
While the switch itself may be of any suitable
construction responsive to changes in speed of
the shaft, the type which I prefer to utilize is 45
that which is more completely shown and de
scribed in United States Patent 1,305,084, which
issued May 27, 1919, to John B. Hansell.
As illustrated in Figs. 10, 11 and 12, this switch
comprises a composite ring H6, sensitive 'to 50
changes in the centrifugal force acting thereon,
mounted directly upon the blower. shaft II2, a
base plate H8, attached, by means of screws I2IJ,
to the end bracket H4 of the blower, and a car
riage I23 mounted in suitable slides on the base 55
plate in a manner to move in a vertical direction
therein.
This carriage supports, by means of an
insulating material bar I25 attached to the lower
end thereof, a pair of contact bridging members
I24 and I25 which are respectively adapted to
selectively make connection with two pairs of
stationary contact members I27 and I28 carried
on an extension of insulating material I30 which
is ?xed to the lower end of the base plate II8.
Connections with the circuits to be controlled are
made by attaching the conductors, as by screws
I29, to these stationary contact members.
Changes in the effective diameter of the com
posite ring I I6 effect an actuation of the carriage
through the medium of suitable operating lugs
I38 and I39 which protrude from the upper por
tion of the carriage and embrace the ring in the
manner indicated by the side View of Fig. 10.
The ring comprises, as is best indicated by Fig. 11,
4
2,050,332
a-nplurality of crescent-shaped'movable members
142- symmetrically pivoted, at their ends I45, to a
'baseplate I43 which is directly attached to the
shaft I I2,.each member being biased inwardly by
a;.spring .Ilil. These-members Hi2 nest snugly
.tion .against burnout due- toaccidental stoppage
or failure of the blower to start is in this man
:ner‘ obtained.
witheach'other because ofa lateral offset 'in each
of them whereby the pivoted-end‘lies closely
For use with the alternating-current supply
circuits which are at the present time almost
universal in locations where ‘it is desired to in
stall hand driers and other comparable motor
adjacent to the base plate I413 and the free end
overlies the adjacent member. The free end of
driven devices, single-phase induction motors are
especially suitable and it is this type of motor
10 each of the'members is restrained ‘in movement
both inwardly and outwardly by apin M8 work~
ing freely in a slot I50 in the underlying member.
iWhen the ring structure is at rest or revolving
atxlow speeds, the crescent shaped members are
all. drawn inwardly‘ by the'springs Ml, as is indi
cated by the showing of Fig. 11. When sufficient
speed is attained by the shaft I 42, each of the
members I132 flies outwardly under the influence
of centrifugal force until stopped by the engage
ment of the pins l £58 with the ends of the slots‘ I50.
As the composite ring i it thus increases in radius,
the outer edge impinges upon the upper lug l38of
the contact carriage and pushes it upwardly in a
uniform and gradual manner, and conversely, as
25 the composite ring M6 ‘decreases in radius with
a decrease in speed, the inner edges of the mem
bers I42 contact the lower lug H9 and push the
carriage downwardly.
Through the action of a pair of bowed springs
I32, embraced between a portion I33 of the car
riage and extensions I36 of the base member
plate, the carriage is biased, in operation of the
switch, toward either limit of its movement path
so that a quick and positive snap actionof the
35 contacts is thereby effected. Thus, when the car
riage is in the lower position illustrated, in which
stationary contact members l2? are bridged by
member I24, the action of these springs is to
strongly hold it in that position and thereby
40 maintain the requisite contact pressure. LikeWise, when the carriage has been moved upwardly
past the midpoint of its movement path, the
springsurge it upwardly with a constantly in~
creasing force until it, reaches its upper position
in which the bridging member B25 is biased
against the stationary members S28, the bridg
ing member I243 having by this movement been
separated from the stationary members lE'I.
The total range of movement of the carriage
50 and its actuating lugs E38 and i353 is made to ex
ceed the variation in the radius of speed-respon
sive ring H5, in order that the crescent shaped
members I42 of this ring will not bear upon these
lugs at the normal speed of the blower shaft M2,
55 the carriage being allowed to snap free thereof,
during each switch actuation, under the in?uence
of bowed springs I32, into its limiting position.
The manner in which the centrifugal switch is
connected in the energizing circuit of the heater
is most clearly illustrated by the diagram of Fig.
13 from which it will be seen that a depression
of ‘the treadle switch Bil ?rst energizes driving
motor 2il'to start the blower is. Shortly before
the blower attains normal speed, the centrifugal
switch‘ actuates the bridging member I25 thereof
upwardly to‘ complete an energizing circuit for
the heater. 90. It will thus be noted that while
an opening of. the control switch 30 deenergizes
both the motor and the heater, upon a closure
70. thereof, heater energization can be eifected only
while the blower is operating, a failure or discon
tinuance of such operation immediately causing
the centrifugal switch to disconnect the ‘heater
from'the power source even though the motor
75'. may continue'to be energized. Effective protec
(3
that I have illustrated as being incorporated in
the improved hand drier of my invention. In
order-that such a single phase motor may be
started, it is necessary to provide it with ‘an
auxiliary-winding, shown in the diagrammatic
representation of‘Fig. 13 at I60, physically dis
placed from the main winding, indicated at I62,
which :main winding derives its energization
directly from the supply conductors 75 through
the control switch 80. In. order to- shiftjthe
vphase position of the current ‘which is supplied
to the. auxiliary-winding I69, it is necessary to
insert in the supply circuit thereof some phase
displacing device such as a capacitor I64, and
it is preferable that this winding be maintained
energized not only during the starting operation 25
but also during the normal full speed running op
eration-of the motor 20.
'
To increase the rapidity of starting of the
motor, it is desirable insituations of this .kind
to utilize a second or starting capacitor I 66 which 30
is connected in the auxiliary winding circuit for
a short‘ period after- current is ?rst supplied to
the motor, the function of this additional capac
itor being to increase the current which circu
lates through the auxiliary winding’ and there 35
by substantially raise the starting torque of the
motor. To be most effective this increase in
current is of such magnitude that damage from
sustained overload would‘ result to the auxiliary
winding I20 were the starting capacitor to be 40
permanently left in the energizing circuit there
of. In the complete hand drier of my invention
shown in Figs. 1 and 2, these capacitors I64 and
I65 are shown as being mounted below the motor
in the lower portion of the angle-iron frame.
To effect a removal of this starting capacitor
as soon’ as the motor has attained full speed, I
utilize the secondset of contacts comprising
bridging member I24 and stationary members I21
of the centrifugal switch, before described as be 50
ing actuated in accordance with the speed of the
driven blower IE3. When the motor and blower
are at rest, the bridging member I24 completes,
as isshown by the diagram of‘ Fig. 13, an active
connection of starting capacitor I66 in the cir
cuit through which auxiliary winding I6!) of the
motor is energized.
'As'soon as the motor and
blo-wer'come up to speed, however, bridging mem
ber I213 is, in the manner already explained,
moved upwardly to thereby interrupt'the circuit
of the starting capacitor to remove it from active
service.
'
Although I have'shown and described'a certain
speci?c embodiment of my invention,'I am fully
aware that many modi?cations thereof are pos
sible. My invention, therefore, is not to be re
stricted except insofar as is necessitated, by the
prior art and by the scope of the appended claims.
vI claim as my invention:
1. An electric drying device comprising, in com
bination, ea draft-producing and air-heating
mechanism, a structural frame for supporting said
mechanism, and an exterior casing adapted to
surround said frame and to form thereabove a
pressure compartment intolwhich said mechanism 75
5
2,050,332
may discharge heated air, said compartment hav
ing an opening through which said air may escape
for direction against objects to be dried.
2. In an electrical drying device, the combina
tion of a structural frame, an air-blower, a driv
?xture, said means comprising a ?exible metal
strip through an opening in which the said ?xture
extends, and grooves provided in the sides of said
arcuate casing opening for slidably retaining the
edges of said strip.
"
5. In an electrical heating device comprising an
ing motor therefor, and an air heater supported
by said frame, an exterior casing adapted to ?t
air-blower, a split-phase induction motor, having
down over and be attached to said frame above
which the upper portion of the casing forms a
a pair of windings, for driving the blower, a source
of power for the motor, a control switch, a circuit
chamber, a partition between said chamber and
the frame-supported mechanism therebeneath,
for energizing one of said motor windings directly
from the power source upon closure of the switch,
said partition having an opening through which
a phase-shifting element, and a circuit for ener
the heated air is blown into the chamber, and said
gizing the other motor winding through said ele
ment upon closure of the switch, the combination
of a centrifugal switch, responsive to the speed 15
of the blower, for interrupting said last-named
circuit when the blower speed is, during a start
ing operation, brought up to a value closely ap
proaching normal.
exterior casing having in the top portion thereof
15 an opening through which said air may escape for
direction against objects to be dried.
3. In an electrical drying device comprising a
casing in a portion of which is formed a pressure
chamber provided with an air-discharge open
20 ing of arcuate contour, the combination of an
air-outlet ?xture, a shaft, the ends of which pro
trude through the sides of the casing, for adjust
ably supporting the ?xture in said arcuate open
ing, means for sealing against air escape the
portions of said opening not occupied by the ?x
ture, and handles attached to said shaft ends
to enable an operator to change the position of
the ?xture in the casing opening and thereby
adjust the directions of air discharge.
30
4. In an electrical drying device comprising a
casing in a portion of which is formed a pressure
chamber provided with an air-discharge open
ing of arcuate contour, the combination of an air
outlet ?xture, a shaft, the ends of which pro
trude through the sides of the casing, for adjust
ably supporting the ?xture in said arcuate open
ing, and means for sealing against air escape the
portions of said opening not occupied by said
6. In an electrical drying device comprising a 20
heater, a blower for forcing air through said
heater, a split-phase induction motor, having a
pair of windings, for driving the blower, a source
of power for the heater and motor, a control
switch, a circuit for energizing one of said motor 25
windings directly from the power source upon
closure of the switch, a phase-shifting element,
a circuit for energizing the other motor winding
through said element upon closure of the switch,
and a circuit through which the heater may be
energized, the combination of a centrifugal switch,
which is responsive to the speed of the blower,
adapted to interrupt the motor-energizing circuit
last named when the blower speed is brought up to
a value closely approaching normal and to, at 35
the same time, complete the said heater energizing
circuit.
R. H. JORDAN.
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