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Патент USA US3027454

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March 27, 1962
3,02 7,444
Filed Nov. 16, 1960
H \S
United States Patent
Patented Mar. 27, 1962
thermostat bulb to seal the bulb from the oven air before
the oven temperature is raised to an abnormal high tem
perature. In addition a cool air supply duct delivers cool
air over the bulb when it is sealed by the shielding means
so that the bulb temperature will always be below the
Walter R. Weeks, Windy Hills, Ky., assignor to General
Electric Company, a corporation of New. York
oven air temperature andlikewise below the maximum
safe operating temperature of the thermostat ?uid. A sepa
rate cool air exhaust and a separate hot air exhaust is pro
The present invention relates to cooking ovens for
vided for separating the oven air from the cooling air.
domestic use and particularly to a means of protecting a 10 While a blower could be used for forcing cool air to the
hydraulic thermostat bulb in a domestic oven which is
thermostat bulb I prefer to take advantage of convection
designed to operate through two temperature ranges such
currents obtained by a natural draft of air through the cool
as a normal cooking range having a maximum tempera
air supply duct for absorbing some of the heat of the bulb
ture of about 600° F. and a higher heat cleaning range
and successfully restricting the thermostat bulb tempera
having a maximum temperature between 750° F. and 15 ture to ‘a maximum temperature of about 600° F. while
950° F.
at the same time the oven temperature will rise to as'high
Hydraulic thermostats having an elongated bulb or
as 950° F. during the heat cleaning cycle.
probe formed on the end of a capillary tube that is joined
My invention will be better understood from the fol
to a bellows or diaphragm within the thermostat housing
lowing description taken in connection with the‘ accom
have been widely used as oven thermostats for many 20 panying drawing and its scope will be pointed out in the
years. The normal oven cooking temperatures have all
appending claims.
been below about 600° F. maximum, and a thermally
FIGURE 1 is a fragmentary side elevational view partly
responsive fluid used in the hydraulic control system have
‘in cross-section of a free-standing electric range showing
been able to withstand this degree of temperature without
the thermostat bulb shielding means embodying the
I Filed Nov. 16, 1960, Ser. No. 69,764
8 Claims. (Cl. 219-65)
However, the known thermally responsive
?uids that are commercially acceptable cannot be op
erated at temperatures much above this value.
25 present invention.
FIGURE 2 is a partial view similar to that of FIGURE
1 showing the shielding means over the thermostat bulb
This invention contemplates the provision of a protec
where the shielding means has been adjusted from the
tive arrangement for the thermally responsive ?uid so that
normal position during cooking of FIGURE 1 to a sealed
a thermostat of the hydraulic type may be used success 30 position which isolates the bulb from the high tempera
fully as a control element in the high temperature oven
ture of the oven air and places the bulb in a cool air
described and claimed in the co-pending application of
Bohdan Hurko, Serial No. 27,926, ?led May 9, 1960,
which is assigned to the General Electric Company, the
Referring in detail to the drawing and in particular to
FIGURE 1, this invention has been shown in one form as
same assignee as in the present invention. As there de 35 app-lied to a free-standing electric range 10, but it should
scribedand ‘claimed, the oven is provided with an auto
be understood that this is for illustrative purposes only and
matic oven cleaning cycle where the temperature of the
that the invention is broad enough to be used in all
oven is raised to a heat cleaning temperature within a
domestic ovens whether they be heated by gas or elec
range of 750° F. and 950° F. so as to burn 01f all food
tricity. The range 10 includes a top cooking surface 11
soil and leave the inner walls of the oven cavity perfectly 40 having a plurality of metal-sheathed surface heating ele
ments 12, a back'splasher 13 containing the various manu
The principal object of the present invention is to pro
ally adjustable control devices 14 for both the surface
vide an adjustable shielding means for the bulb of a hy
heating elements and the oven elements, and an oven
draulic thermostat and an air cooling means for the bulb
, cavity 15 formed by an oven liner 16 and a front-opening
when it is so shielded so that the oven temperature may be 45 drop door 17 which is hinged along its bottom edge as
raised to the vicinity of 950° F. without injuring the
in conventional oven designs. The present invention is
bulb or the ?uid carried therein.
concerned with the design of the oven components so
A further object of the present invention is to sea-1 the
that no further description will be given of the other
bulb of a hydraulic thermostat from the oven air while
features of the range which form no part of the present
placing the bulb in a cool air stream when the oven is
operating in its abnormal high temperature condition so
The oven liner 16 is a box-like construction having a
as to hold the maximum temperature of the bulb below
bottom wall (not shown), parallel side walls 18, a back
a safe operating limit.
wall 19, and a top wall 20 as well as an open front that
is adapted to be closed by the front door 17. As in
A still further object of the present invention is to
provide an adjustable shielding means for the bulb of a 55 standard electric ovens there is a lower heating element
hydraulic thermostat so that the bulb is in a cool air
or baking unit (not shown) and an upper heating element
stream when the oven temperature is to be raised to an
or broil unit (not shown) which is disposed slightly be
abnormal high temperature, and means are provided for
low the top wall 20 of the oven liner. Both the bake
throttling the exhaust to a certain degree when the oven
and broil units may be plug-in units that are inserted into
is operating during normal cooking and to another degree
when the oven is operating at the abnormal high tem
electrical connectors or receptacles positioned in suitable
openings in the back wall 19 of the oven liner. 'Ihe
oven liner 16 is surrounded by a relatively thick blanket
The present invention is incorporated in an oven which
of insulation 21 formed of a suitable material such as
has controlled heating means capable of elevating the
?berglass or the like for preventing the escape of heat
oven temperature to a value materially in excess of 600° 65 from the oven cavity as well as to hold down the operat
F. in accordance with the invention of the aforementioned
co-pending application of Bohdan Hurko. For control
ing temperature of the outer surface of the range body 10'.
It has been found that the walls of the oven liner may
be cleaned automatically without hand scrubbing if the
ling the heating means, a hydraulic thermostat is provided
having a bulb ?lled with a thermally responsive liquid and 70 'oven wall temperature is raised to a temperature between
arranged to be placedin a heat sensitive position in the
about 750° F. and 950° F. and held for a suitable‘ length
oven. An adjustable shielding means is combined with the
of time for burning off the food soil and grease spatter.
extend for nearly the entire length of the housing.
Also it is known that if the temperature does not reach
The ‘
openings 44 and 46 are generally opposite each other,
a su?iciently high value in some particular area of the
‘ oven liner, the soil will not be completely removed from
this area. This'was one of the major problems faced in
while the openings 45 and 48 form a pair that are like
wise opposite each other. Finally the last slot 47 is ad-.
jacent the slot 46. 'The rotatable damper 43 is tubular
in shape and has a generally D-shaped cross-section with
designing the. oven door asis fully explained in the afore
mentioned co-pending Hurkoapplication. Door panels
had, to be_ designed, gasketing'inethodswere devised, and
a pair of opposite openings 50 and ‘51 in the rounded‘,
section of the tube for purposes which will be explained
a source of additional heat was introduced; namely, the
mullion, heater 23 which encircles the periphery of the
A cool air supply duct 52 is verticallydisposed behind
front portion of the oven liner. Further details of the 10
the back wall 19 of the oven liner and it has an inlet
construction of the front portion of the oven will not
be discussed here as they do not form part of the present
' end (not shown) located near the base of the rangeltl
and an. outlet end 53 that is fastened over the slot 48 in
the housing 42 of the shielding means. Similarly there
During the heat cleaning cycle, smoke and odors are
generated from the food soil and, grease spatterings that 15 is a cool air exhaust duct'r54 that has one end fastened
over the slot 45 in the cylindrical housing while its» 012
are being burned oifthe surfaces of the oven liner. This
smoke must be eliminated. otherwise it might become
‘ posite end extends outwardly andupwardly through a suit
able opening in the top wall 2t? of, the oven liner and dis“
charges under the cooktop 11‘ as at 55. Looking at FIG‘
discharged through an. exhaust duct25 which empties 20 URE 1 it is seen. that the rotatable damper 43 is turned
to one position where it‘ covers over the opening 48 in
. into a-smoke eliminator such as; the catalyticsmoke elim
toxic and cause bodily harm. Accordingly. the gases and
grease laden water vapor. created in the oven cavity are
the cool air supply duct 52 as well as‘ the opening 45in
inator .26 of the general type disclosed in. the United
States patent to ‘Stanley B. Welch, No._2,900,483,_entitled
the cool air exhaust duct 54. Moreover, the damper
stops any air ?ow through slot 47. The presence of cool
Electric. Catalytic Contact Device ‘and dated August 18,
1959, which is assigned to. the General Electric Company 25 air is shown by the elongated arrow lines ‘49. ‘ At the
same time the opposite openings 50 and 51 of'the damper
the same-,assignee as in the present invention. The house
43 are in alignment with the slots 44 and 46 to‘ allow
ing of the smoke, eliminator is formed by ‘a pair of pan
the oven exhaust to pass out through the smoke elimina
1 shape members 27 and 28 which are fastened-together
;by rivets 29 alongthe outer periphery thereof.‘ A parti
tion. 30 divides‘ the housing into two sections, a large sec
tion 31 and a smaller section 32. These two sections
arejoined by a ring of openings 3-3 which are formed in
the partition and extend completely around the housing.
tor 26. This is theposition of the damper as shown in
FIGURE 1 during the normal cooking operations where:
the thermostat bulb is exposed to the oven air tempera
tures and to the radiant energy from the oven heating
elements previously mentioned. Accordingly the hot
exhaust is as shown» by the dotted arrow lines 60
The/larger section 31 of the housing incorporates a coiled 35 oven
indicating that the hot oven air flows overrthe bulb 40
metal sheathed heating unit 34 which is similar in basic
through the exhaust duct 25, the smoke eliminatorzo, and
construction to the metal-sheathed surface heating element ..
out through the ducts 37 and 38, At the same time the
12 mentioned previously; A catalytic screen 35 is posi
relatively cool room air present in the vair supply duct
' tioned in parallel relation to the coiled heating unit 34
52 is blocked by the damper 43 from ?owing over the
so that the oven et?uent must make multiple passes 40 bulb.
through the screen and over the several turns of the heat
Note that in FIGURE 2 the damper has been rotated
ing element before passing through‘ the ring of openings 33
clockwise about 90° so as to close the slot 44 and open
in the-partition 30. The heating element 34. is energized
by means of suitable electrical connections (not shown)
the slots 48, 45, and 47, while the slot 46 is always left
open because it communicates with'the smoke eliminator
so as to heat the catalytic screen 35 to its optimum reac 45 26 to facilitate the removal of the oven exhaust whenever a
tion temperature for oxidizing the. oven ef?uent and con
the heating means of the oven are energized. This is
the position of the damper when the oven is to be o1»v
as carbon dioxide andvwater vapor. The top of the
erated on an automatic heat cleaning cycle and the oven
smoke eliminator 26 extends into a horizontally disposed
air is to rise to a temperature between about 750° F.
air duct 37 under the cooking surface 11 that has a ver 60 and 950° F. In order. to insure that the maximum tern“
tical extension 38 communicating with the underside of
perature of the bulb 40 does not rise above 600° F. the
one of the surface heating elements 12 through which it
bulb 40 is sealed from the oven air temperature by the
discharges. It will be understood that the vertical exten
90° rotation of the damper, and the bulb is- placed in a
sion 38 is horizontally o?fset from the smoke eliminator
cool air stream which flows through the air supply duct
26. so as to avoid the‘ direct spillage of ?uids into the
52 by convection that is assisted by the warm tempera
smoke eliminator.
ture of the back wall 19 of the oven liner. It is impor
As shown in both FIGURES 1 and 2, there is a stand
tant not to mix the relatively cool room air with the high
ard- elongated thermostat bulb 40 that extends alongthe
temperature oven air and this is accomplished by the
backewall 19 of the oven liner near the top thereof. One
damper allowing the oven air to pass through the. slot 47
vertingthe smoke particles into less obnoxious gases such
end of the bulb is closed while the other end is joined
to a capillary tube (not shown) that connects to a bel
lows or diaphragm (not shown) with an oven thermostat
in the cylindrical housing 42 and then through the slot
46 where it moves through the exhaust duct 25, the smoke
eliminator 26, and then through the ducts 37 and 38.
Moreover, the damper serves to throttle the oven exhaust
14 that is located in the backsplasher 13 of the range so
in varying degrees during normal cooking as compared
that the temperature changes within the oven may be re
?ected by the expansion and contraction of the ?uid con 65 with the heat cleaning cycle to avoid the cooling down
of the oven during heat cleaning.
tained within the bulb. It has‘been found necessary to
limit. the maximum temperature of the fluid within the
Having described above my inventionv of a simple ad
justable shielding means for a thermostat bulb in a high‘,
bulb 40 to about 600° F. while the oven air temperature
temperature oven, it will be readily apparent to those
must. reach as high as from 750° F. to 950° F.
My invention accomplishes this purpose by the use of 70 skilled in this art that this invention is not limited to the
particular embodiment disclosed which shows a long cy
an adjustable shieldingmeans 41 which encompasses the
lindrical element to encompass the straight portion of the
thermostat bulb 4G and includes both a. cylindrical hous
thermostat bulb. A short cylindrical member could be
ing 142 and a rotating. damper 43. The cylindrical hous~
used if the bulb is wound in the form of a spiral or is
ing 4?,v is- provided with a series of ?ve longitudinally ex
tending elongated’ slots 44, 45, 46, '47, and 48. These slots 75 folded back upon itself into a hair-pin shape. Also it is
to be noted that the cylindrical housing for the damper
need not be located exactly as shown, but that it could
be built into the back wall 19 of the oven liner completely
out of the way of any cooking utensils that might be ,
is exposed to the oven air during normal cooking oper
4. A hydraulic thermostatic control system as recited
in claim 3 wherein the cool air supply duct extends down
placed in the oven. Likewise the air supply duct 52 and 5 the back of the oven and has an inlet end that is open
the air exhaust duct 54 could both be located at the back
to room air, this relatively cool air being moved by con
of the oven liner in order to simplify the construction and
vection through the duct and over the thermostat bulb,
remove as much structure as possible from the oven
and a smoke eliminating device located within the second
exhaust duct for removing large portions of the odor
Other modi?cations of this invention will occur to those 10 and smoke from the oven e?luent.
skilled in this art and it is to be understood, therefore,
5. A domestic oven having a hydraulic thermostatic
, that this invention is not limited to the particular em
control system for controlling the oven heating means,
bodiments disclosed but that it is intended to cover all
the hydraulic thermostatic control including a bulb ?lled
modi?cations which are within the true spirit and scope
with a heat sensitive ?uid, shielding means for protecting
of this invention as claimed.
15 the thermostat bulb from rising above a maximum allow
What I claim as new and desire to secure by Letters
able temperature when the temperature of the oven air
Patent of the United States is:
rises above said maximum allowable temperature, said
1. A hydraulic thermostatic control system for con
shielding means including a damper which in one position
trolling the heating means of an oven, said control sys
exposes the bulb to the oven air temperature and in an
tem comprising a thermostat bulb ?xedly mounted within 20 other position seals the bulb from the heat within the
an oven, a temperature responsive ?uid ?lling said ther
oven, and air circulation means cooperating with said
mostat bulb for controlling said heating means respon
shielding means for directing relatively cool air over the
sively to the expansion and contraction of the ?uid, and
bulb while the bulb is sealed by the damper, said cir
protective means for preventing an excessive temperature
culation means being rendered inoperative by the damper
rise in said ?uid, said protective means including an adjust 25 when the damper exposes the bulb to the oven air.
able shielding means having one position for sealing the
6, A domestic oven, heating means for the oven for
thermostat bulb from the oven air and a second position
normal cooking operations as well as for an automatic
that exposes the bulb to the oven air, there being a supply
heat cleaning cycle to burn off the food soil of the inner
duct directing cool air over the bulb when the shielding
walls of the oven, a hydraulic thermostatic control means
means is sealed over the bulb, and a ?rst exhaust duct 30 for controlling the oven heating means and including a
leading from the bulb for causing the cool air to ?ow past
thermostat bulb mounted within the oven, a temperature
the bulb and through the exhaust duct, a second exhaust
responsive ?uid ?lling said bulb, and shielding means co
duct leading from the vicinity of the bulb for removing
operating with the thermostat bulb to limit the tempera
the hot exhaust gases from the oven when the bulb is
ture of the bulb below a maximum allowable tempera
sealed by the shielding means in its ?rst position, the 35 ture while the temperature of the oven air rises above
shielding means in its second position sealing otf both the
this maximum temperature during a heat cleaning cycle,
cool air supply duct and the ?rst exhaust duct while ex
said shielding means comprising a damper having at least
posing the bulb to the oven air and opening the second
two positions, a ?rst position exposing the bulb to the
exhaust duct to remove the oven air by passing the oven
oven air during normal cooking operations, and a second
exhaust over the bulb and out the second exhaust duct. 40 position overlying the bulb for sealing the bulb from the
2. A hydraulic thermostatic control system for con
oven air, a cool air supply duct cooperating with the
trolling the heating means of an oven, said control sys
tem comprising a thermostat‘ bulb ?xedly mountediwithin
an oven, a temperature responsive ?uid ?lling said thermo
damper and being opened by the damper when the damper
seals over the bulb so that the cool air absorbs heat
from the bulb and carries the heat outside of the oven,
stat bulb for controlling said heating means responsively 45 said damper closing the air supply duct when the damper
to the expansion and contraction of ?uid, and protective
exposes the bulb to the oven air.
means for preventing an excessive temperature rise in
7. A domestic oven as recited in claim 6 wherein the
said ?uid when the temperature within the oven rises to
air supply duct has a natural draft that is provided by the
an amount above the safe operating temperature of the
inlet end of ‘the duct being positioned below the oven,
fluid in the bulb, said protective means including an 50 and the central portion of the duct being located closely
adjustable shielding means in combination with a cool
adjacent the back wall of the oven so that the heat from
air supply duct so that when the oven temperature is to
the oven is transmitted to the air in the duct to acceler
7 rise to an excessive high temperature the shielding means
ate the air movement.
seals the bulb from the oven air and connects the bulb
8. A domestic oven as recited in claim 6 wherein the
to the ?ow of cool air from the air supply means so that 55 oven has at least two exhaust ducts, a ?rst exhaust duct
the temperature of the bulb is kept below its maximum
that is always open to remove the exhaust from the oven
safe temperature while the oven temperature rises be
yond this point, the adjustable shielding means being
during both normal cooking operations and the heat
’ cleaning cycle, a second exhaust duct cooperating with the
movable to a position for sealing the air supply duct and
shielding means for carrying o? the relatively cool air
exposing the bulb to the oven air for normal cooking 60 that passes over the bulb when the bulb is sealed by the
damper, the damper serving to control the rate of ex
3. A hydraulic thermostatic control system as recited
haust flow from the oven in both positions of the damper.
in claim 2 with the addition of a ?rst exhaust duct di
rected toward the thermostat bulb for removing the cool
air from around the thermostat bulb when the shielding 65
means seals the bulb from the oven air, and a second
exhaust duct for removing the oven air in both positions
of the shielding means, both the air supply duct and the
?rst exhaust duct being closed when the thermostat bulb
References Cited in the ?le of this patent
Harding _____________ __ Dec. :16, 1958
‘Great Britain ________ __ June 22, 1955
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