U.S. patent number 3,703,988 [Application Number 05/093,540] was granted by the patent office on 1972-11-28 for oven control system.
This patent grant is currently assigned to Robertshaw Controls Company. Invention is credited to Charles D. Branson, Francis S. Genbauffe.
United States Patent |
3,703,988 |
Branson , et al. |
November 28, 1972 |
OVEN CONTROL SYSTEM
Abstract
A fuel control system for an oven having a source of fuel and
main burner means. A pneumatically operated main valve is utilized
for interconnecting the source to the burner when the main valve is
actuated and for disconnecting the source from the main burner when
the main valve is deactuated. A manually settable and
thermostatically operated valve is provided for interconnecting a
pneumatic control signal to the main valve to actuate the same when
a temperature effect of the burner is below a set temperature
effect and for disconnecting the pneumatic control signal from the
main valve to deactuate the same when the temperature effect of the
burner is above the set temperature effect, the thermostatically
operated valve having a manually settable construction for
controlling the cooking temperature effect of the burner and having
a modifying construction for modifying the manually settable
construction for controlling a burnoff cleaning temperature effect
of the burner.
Inventors: |
Branson; Charles D.
(Greensburg, PA), Genbauffe; Francis S. (Irwin, PA) |
Assignee: |
Robertshaw Controls Company
(Richmond, VA)
|
Family
ID: |
22239482 |
Appl.
No.: |
05/093,540 |
Filed: |
November 30, 1970 |
Current U.S.
Class: |
236/15A; 126/39C;
236/47; 236/46D; 236/46R |
Current CPC
Class: |
F24C
3/128 (20130101) |
Current International
Class: |
F24C
3/12 (20060101); F23n 005/02 () |
Field of
Search: |
;236/15A,47,80,86,46D
;126/39C ;431/41 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Wayner; William E.
Claims
What is claimed is:
1. A fuel control system for an oven having a source of fuel and
main burner means comprising a pneumatically operated main valve
means for interconnecting said source to said burner means when
said main valve means is opened by said main valve means being
actuated and for disconnecting said source from said burner means
when said main valve means is closed by said main valve means being
deactivated, and a manually settable thermostatically operated
valve means having a thermostatically operated valve member for
interconnecting a pneumatic control signal to said main valve means
to actuate the same when said thermostatically operated valve means
senses a temperature effect of said burner means below any
temperature effect setting of said thermostatically operated valve
means and for disconnecting said pneumatic control signal from said
main valve means to deactuate the same when said thermostatically
operated valve means senses a temperature effect of said burner
means above said temperature effect setting, said thermostatically
operated valve means having manually settable means for selecting
the cooking temperature effect setting of said thermostatically
operated valve means for a cooking operation of said burner means
and having modifying means for modifying said manually settable
means for selecting a burn-off cleaning temperature effect setting
of said thermostatically operated valve means for a cleaning
operation of said burner means.
2. A fuel control system as set forth in claim 1 wherein said
modifying means is also adapted to modify said manually settable
means for selecting a warmth retaining and non-cooking temperature
effect setting of said thermostatically operated valve means for a
warmth retaining and non-cooking operation of said burner
means.
3. A fuel control system as set forth in claim 1 wherein said
modifying means comprises a heat motor.
4. A fuel control system as set forth in claim 1 wherein said
pneumatic control signal is provided from said source of fuel by
said thermostatically operated valve means.
5. A fuel control system as set forth in claim 1 wherein said main
valve means comprises a diaphragm valve means.
6. A fuel control system for an oven having a source of fuel and
main burner means comprising a pneumatically operated main valve
means for interconnecting said source to said burner means when
said main valve means is opened by said main valve means being
actuated and for disconnecting said source from said burner means
when said main valve means is closed by said main valve means being
deactivated, a manually settable thermostatically operated valve
means for interconnecting a pneumatic control signal to said main
valve means to actuate the same when said thermostatically operated
valve means senses a temperature effect of said burner means below
a set temperature effect of said thermostatically operated valve
means and for disconnecting said pneumatic control signal from said
main valve means to deactuate the same when said thermostatically
operated valve means senses a temperature effect of said burner
means above said set temperature effect, said thermostatically
operated valve means having manually settable means for controlling
the cooking temperature effect of said burner means and having
modifying means for modifying said manually settable means for
controlling a burn-off cleaning temperature effect of said burner
means, said burner means having pilot burner means therefor, and a
safety valve means disposed intermediate said thermostatically
operated valve means and said main valve means to prevent said
pneumatic signal from being directed to said main valve means only
when no flames exist at said pilot burner means.
7. A fuel control system as set forth in claim 1 wherein said
burner means comprises a single burner, said thermostatically
operated valve means being settable for a baking temperature effect
of said burner and being settable for a broiling temperature effect
of said burner.
8. A fuel control system as set forth in claim 7 wherein said
modifying means is also adapted to automatically modify said
manually settable means to provide a warmth retaining and
non-cooking temperature effect of said burner following at least
one of said baking and broiling operations of said burner.
9. A fuel control system as set forth in claim 1 wherein said
burner means comprises a bake burner and a broil burner
respectively received in said oven, said main valve means
comprising two main valves respectively for said burners.
10. A fuel control system as set forth in claim 9 wherein said
manually settable means of said thermostatically operated valve
means is only adapted to direct said pneumatic signal to said main
valve for said bake burner when a baking operation is selected
thereby and is only adapted to direct said pneumatic signal to said
main valve for said broil burner when a broiling operation is
selected thereby.
11. A fuel control system as set forth in claim 9 wherein said
manually settable means of said thermostatically operated valve
means is adapted to substantially simultaneously direct said
pneumatic signal to both main valves when a burn-off cleaning
operation is selected thereby.
12. A fuel control system as set forth in claim 9 wherein said
burners respectively have pilot burners therefor, a pair of safety
valves respectively disposed between said thermostatically operated
valve means and said main valves to respectively prevent said
pneumatic signal from being directed to the respective main valve
only when no flames exist at the respective pilot burner.
13. A fuel control system as set forth in claim 9 wherein said
manually settable means of said thermostatically operated valve
means is adapted to substantially direct said pneumatic signal to
both main valves when a burn-off cleaning operation is selected
thereby, a temperature responsive valve being disposed between said
main valve for said bake burner and said thermostatically operated
valve means to prevent said signal from reaching that main valve
until after said broil burner has caused a predetermined
temperature effect in said oven below the burn-off cleaning
temperature effect.
14. A fuel control system as set forth in claim 13 wherein said
temperature responsive valve has means for preventing said signal
from reaching said main valve of said bake burner when said
temperature effect in said oven exceeds said burn-off cleaning
temperature effect.
15. A fuel control system as set forth in claim 13 wherein said
temperature responsive valve has means for preventing said signal
from reaching said main valve of said broil burner when said
temperature effect in said oven exceeds said burn-off cleaning
temperature effect.
16. A fuel control system as set forth in claim 9 wherein said oven
has an air supply means for delivering air, a pair of air sensors
respectively for said main valves and preventing said signal from
actuating said main valves unless said air supply means is
delivering said air.
Description
This invention relates to a control system for an oven or the
like.
One of the features of this invention is to provide a fuel control
system for an oven wherein the main control device is adapted to
permit the operation of the fuel control system for normal cooking
operations as well as for high temperature burn-off cleaning
operations.
Another feature of this invention is to provide such a fuel control
system wherein both a bake burner means and a broil burner means
are disposed in the same oven cavity.
Another feature of this invention is to provide such a fuel control
system wherein only one of the burners is initially operated during
a burn-off cleaning operation until after the temperature effect in
the oven reaches a predetermined temperature below the burn-off
temperature at which predetermined temperature the other burner
means is then operated simultaneously with the one burner
means.
Another feature of this invention is to provide such a fuel control
system wherein once the burn-off cleaning temperature effect is
produced in the oven, the control system cycles on and off only one
of the burner means while providing continuous operation of the
other burner means to maintain the temperature in the oven at the
burn-off cleaning temperature.
In particular, one embodiment of this invention provides a fuel
control system for an oven that has a source of fuel and a main
burner means, the control system including a pneumatically operated
main valve means for interconnecting the source to the burner means
when the main valve means is opened by the main valve means being
actuated and for disconnecting the source from the burner means
when the main valve means is closed by the main valve means being
deactuated. A manually settable and thermostatically operated valve
means is provided for interconnecting a pneumatic control signal to
the main valve means to actuate the same when the thermostatically
operated valve means senses a temperature effect of the burner
means below a set temperature effect of the thermostatically
operated valve means and for disconnecting the pneumatic control
signal from the main valve means to deactuate the same when the
thermostatically operated valve means senses a temperature effect
of the burner means above the set temperature effect. The
thermostatically operated valve means has manually settable means
for controlling a cooking temperature effect of the burner means
and has modifying means for modifying the manually settable means
for controlling a burn-off cleaning temperature effect of the
burner means. Such modifying means is also adapted to modify the
manually settable means for controlling a warmth retaining and
non-cooking temperature effect of the burner means. The modifying
means can comprise a heat motor.
Accordingly, it is an object of this invention to provide an
improved oven control system having one or more of the novel
features set forth above or hereinafter shown or described.
Other objects, uses and advantages of this invention are apparent
from a reading of this description which proceeds with reference to
the accompanying drawings forming a part thereof and wherein:
FIG. 1 is a schematic view illustrating one embodiment of the oven
control system of this invention.
FIG. 2 is a view similar to FIG. 1 and illustrates another
embodiment of the fuel control system of this invention.
FIG. 3 is a view similar to FIG. 1 and illustrates another
embodiment of the oven control system of this invention.
FIG. 4 is a view similar to FIG. 1 and illustrates another
embodiment of the oven control system of this invention.
FIG. 5 is a schematic cross-sectional view illustrating an improved
control device that is utilized in the oven control system of FIGS.
1-4.
FIG. 6 is a view similar to FIG. 5 and illustrates the control
device in a keep warm setting position thereof.
FIG. 7 is a view similar to FIG. 5 and illustrates the control
device in a burn-off oven cleaning position thereof.
FIG. 8 is a schematic cross-sectional view illustrating the main
valve structure utilized in the oven control system of FIGS.
1-4.
FIG. 9 is a view similar to FIG. 8 and illustrates an intermediate
operating position of the main valve means.
FIG. 10 is a view similar to FIG. 8 and illustrates the main valve
means in an open condition thereof.
FIG. 11 is a view similar to FIG. 8 and illustrates another
embodiment of the main valve means of this invention.
FIG. 12 is a view similar to FIG. 11 and illustrates the main valve
means of FIG. 11 in an open condition thereof.
While the various features of this invention are hereinafter
described and illustrated as being particularly adapted to provide
control means for a fuel burning cooking apparatus, it is to be
understood that the various features of this invention can be
utilized singly or in any combination thereof to provide control
means for other devices as desired.
Therefore, this invention is not to be limited to only the
embodiments illustrated in the drawings, because the drawings are
merely utilized to illustrate some of the wide variety of uses of
this invention.
Referring now to FIG. 1, an improved oven control system of this
invention is generally indicated by the reference numeral 20 and
comprises a fuel source manifold 21 having the conventional on-off
valve means 22 therein, a main burner means 23, a main valve means
24 for interconnecting the fuel source 21 by means of an inlet
conduit means 25 to an outlet conduit means 26 that leads to the
main burner 23, a pilot burner means 27 being adapted to be
continuously supplied fuel from the inlet conduit 25 through the
main valve means 24 and to a conduit means 28 leading to the pilot
burner 27 so that the pilot burner 27 can ignite fuel issuing from
the main burner means 23, a main control device 29 for directing a
control signal from the source conduit 25 by way of a conduit 30 to
a conduit means 31 that leads to the main valve means 24 so as to
actuate the main valve means 24 and interconnect the inlet conduit
25 with the outlet conduit 26 and for disconnecting that control
signal from the main valve means 24 to cause the main valve means
24 to disconnect the inlet conduit 25 with the outlet conduit 26, a
safety valve means 32 disposed in the control signal conduit 31 for
preventing the passage of a control signal therethrough unless a
detector portion 33 thereof detects the existence of flame means at
the pilot burner 27, and a temperature sensing bulb 34
interconnected to an expandible and contractible power element 35
of the main control device 29 by a capillary tube 36 whereby the
temperature sensing bulb 34 senses the output temperature effect of
the burner means 23 in the oven (not shown) utilizing the same.
In general, the main control device 29 of the control system 20 can
be manually set by the housewife or the like at any desired cooking
temperature and the same will cause the opening and closing of the
main valve means 24 so as to cycle the main burner means 23 off and
on to maintain the temperature output effect of the oven at the
selected output temperature. In addition, the main control device
29 can be set at a high temperature burn-off cleaning operation
position thereof whereby the main control device 29 will cause the
main valve means 24 to cycle on and off the main burner means 23 so
as to produce a high temperature burn-off cleaning temperature
effect in the oven, such as 900.degree.F or the like.
The main control device 29 also includes means for automatically
modifying the setting of the same to produce a warmth-retaining and
non-cooking temperature in the oven by cycling the main valve means
24 to produce such warmth-retaining and non-cooking temperature in
the oven as will be apparent hereinafter. Of course, the control
device can be initially set for a warmth-retaining and non-cooking
temperature, if desired.
Referring now to FIGS. 5, 6 and 7, the main control device 29
comprises a housing means 37 containing a valve block portion 38
provided with a valve surface 39 interrupted by an inlet passage 40
that is adapted to be interconnected to the conduit 30 of the
control system 20 in any suitable manner and leads to a chamber 41
in the valve block 38 that is adapted to be interconnected to
another chamber 42 therein by a valve seat 43. The valve seat 43 is
adapted to be opened and closed by a ball valve 44 normally urged
to an open position by a compression spring 45 disposed in the
chamber 42 whereby the compression spring 45 tends to force the
ball valve 44 against an end 46 of a stem 47 carried by a movable
wall 48 of the power element 35 that has its threaded portion 49
adjustably fixed to the housing means 37 in a conventional
manner.
The chamber 42 in the valve block 38 is interconnected to a pair of
passages 50 and 51 with the passage 50 leading to and interrupting
the valve surface 39 of the block 38 and with the passage 51
leading to another chamber 52 in the valve block 38.
The chamber 52 in the valve block 38 is adapted to be
interconnected to another chamber 53 in the valve block 38 by a
valve seat 54, the valve seat 54 being adapted to be opened and
closed by a ball valve 55 normally urged to an open position by a
compression spring 56 disposed in the chamber 53 whereby the force
of the compression spring 56 urges the ball valve 55 against an end
57 of a pin 58 having its other end 59 engageable by a bimetal
blade 60 of a modifying means 61 of the control device 29 carried
by the housing means 37 thereof and in the embodiment illustrated
in FIGS. 5-7 comprising a heat motor arrangement.
In particular, the heat motor arrangement 61 includes a heating
coil 62 for the bimetal blade 60 which has one end 63 thereof
secured to the housing means 37 and the other end 64 thereof free
from the housing means 37 and being adapted to engage against the
end 59 of the pin 58. When the blade 60 is unheated, the natural
warp thereof tends to urge the end 64 of the blade 60 to the left
in FIG. 5 so as to continuously bear against the pin 58 and
overcome the force of the compression spring 56 so as to maintain
the ball 55 seated against the valve seat 54. However, when current
is permitted to flow through the coil 62 which has its opposed ends
65 and 66 respectively interconnected to externally extending
terminals 67 and 68, the heat produced by the coil 62 causes the
blade 60 to warp to the right in the manner illustrated in FIGS. 6
and 7 to not only move the end 64 of the blade 60 away from the pin
58 so as to permit the compression spring 53 to open the ball valve
55 away from the valve seat 54, but also to carry therewith a latch
member 69 having one end 70 thereof pivoted to the housing means 37
by a pivot pin 71 and the other end 72 thereof carrying a member 73
having an opening 74 passing therethrough and receiving the blade
60 therethrough. The latch member 69 has a notch 75 therein and a
cam surface 76 adjacent the notch 75 for a purpose hereinafter
described.
The chamber 53 in the valve block 38 is interconnected to a passage
77 that also interrupts the valve surface 39 of the valve block 38.
A valve member 78 is disposed against the valve surface 39 and is
illustrated in FIG. 5 as being a slide disc valve and schematically
in FIG. 1 as being a cock or plug valve. However, it is to be
understood that the valve member 78 can be of any desired
configuration as the purpose thereof is merely to interconnect one
of the passages 50 or 77 to the conduit 31 while blocking the other
of the passages 50 and 77 from the conduit 31.
For example, the control device 29 includes a control knob 79
secured on a control shaft 80 threaded into a threaded bore 81 of
the valve block 38 and being suitably interconnected to the valve
member 78 by tying means 82 or the like so that when the control
knob 79 is disposed in any on cooking position thereof, the passage
50 of the valve block 38 is interconnected to the conduit 31 while
the passage 77 is completely blocked from the passage 31. However,
when the control knob 79 is set in a burn-off cleaning temperature
position thereof the tying means 82 causes the valve member 78 to
block the passage 50 from the conduit 31 while interconnecting the
passage 77 to the conduit 31 for a purpose hereinafter
described.
The control shaft 80 of the control device 29 has a disc 83 fixed
at the end 84 thereof so that the axial position of the disc 83 in
the housing 37 is controlled by the threaded relation of the shaft
80 in the threaded bore 81. A compression spring 85 has one end 86
bearing against the disc 83 and the other end 87 thereof bearing
against an end 88 of a lever 89 having its other end 90 receivable
in the notch 75 of the latch member 69 when the latch member 69 is
disposed in the position illustrated in FIG. 5. An intermediate
portion 91 of the lever 89 bears against a transverse pin 92
carried by the stem 47 of the power element 35 whereby the force of
the compression spring 85 and the force of another compression
spring 93 disposed between the valve block 38 and the end 90 of the
lever 89, as well as the force provided by the valve spring 45,
tend to pivot the lever 89 in a clockwise direction about its
pivoted end 90 in opposition to any downward movement of the
moveable wall 48 of the power element 35 for a purpose hereinafter
described.
Another lever 94 is carried in the housing means 37 and has an end
95 for pivoting on a fulcrum ledge 96 of the valve block 38 as a
compression spring 97 is disposed between the valve block 38 and
the other end 98 of the lever 94 to tend to pivot the same in a
clockwise direction about the pivot point 96. However, an
intermediate portion 99 of the lever 94 has an opening 100 passing
therethrough and receiving the control shaft 80 whereby an
embossment 101 of the intermediate portion 99 of the lever 94 bears
against the disc 83 carried by the shaft 80 so that the disc 83
prevents the spring 97 from carrying the lever about the fulcrum
point 96 until the disc 83 is moved upwardly a sufficient distance
as illustrated in FIG. 7 to cause the lever 94 to act against the
lever 89 in a manner hereinafter described.
The fill for the temperature sensing bulb 34, capillary tube 36 and
power element 35 can be an inert gas, such as helium, since the
control device 29 of this invention will respond to temperatures as
high as 900.degree.F and the like.
The lever 89 when freed from the notch 75 of the latch member 69 in
the manner illustrated in FIGS. 6 and 7, is adapted to have end 88
engaged against a fulcrum embossment 102 on the housing means 37 by
the force of the compression spring 85 so that the lever 89 will
then pivot about the fulcrum point 102 for a purpose hereinafter
described.
The main valve means 24 for the control system 20 previously
described is illustrated in detail in FIGS. 8-10 and will now be
described.
As illustrated in FIG. 8, the main valve means 24 includes a
housing means 103 having an inlet 104 for interconnecting to the
inlet conduit 25 and an outlet 105 for coupling to the outlet
conduit 26 with the inlet 104 being separate from the outlet 105 by
a valve seat 106 projecting into a chamber 107 of the housing means
103. A flexible diaphragm 108 is carried by the housing means 103
to define one side of the chamber 107 and separate the same from
another chamber 109 of the housing means 103, the flexible
diaphragm 108 carrying a rigid valve member or plate 110 for
opening and closing the valve seat 106. A compression spring 111 is
disposed in the chamber 109 to normally tend to urge the valve
member 110 and its associated diaphragm 108 in a valve seat closing
direction.
Two other flexible diaphragms 112 and 113 are carried by the
housing means 103 with the diaphragm 113 cooperating with the
housing means 103 to define a chamber 114 and in combination with
the diaphragm 112 a chamber 115 therebetween while the diaphragm
112 cooperates with the housing 103 to define another chamber
116.
The flexible diaphragm 113 carries a rigid backing member 117
carrying a tubular extension 118 having an inwardly turned end 119
secured to an inner periphery 120 of the diaphragm 112 that defines
an opening 121 passing centrally therethrough and being aligned
with a resulting opening 122 at the turned end 119 of the tubular
member 118. A ball valve 123 is carried in the tubular extension
118 and is normally urged by a compression spring 124 to seat
against the opening 122 and close the same, the tubular extension
118 having opening means 323 passing therethrough to interconnect
the interior of the tubular member 118 with the chamber 115.
The housing 103 has a wall portion 125 between the chambers 109 and
116, the wall portion 125 having a tubular projection 126 extending
into the chamber 116 and defining a valve seat 127 at the open end
thereof adapted to be opened and closed by the ball 123 since the
projection 126 is fully receivable into the openings 121 and 122 of
the diaphragm 112 and extension 118 as fully illustrated in FIGS. 9
and 10.
A compression spring 128 is disposed in the chamber 116 to normally
tend to urge the diaphragm 112 and, thus, the diaphragm 113 through
the tubular extension 118 to the right in FIG. 8 so that the ball
valve member 123 is held away from the valve seat 127.
The chambers 109 and 116 of the main valve means 24 are disposed in
fluid communication with each other by openings 125' passing
through the intermediate wall 125 of the housing 103.
The valve seat 127 of the tubular extension 126 of the wall 125 of
the housing 103 is interconnected to a passage 129 formed in the
housing means 103 and leading from the inlet 104 to an outlet
passage 130 that is interconnected to the conduit 28 leading to the
pilot burner 27 as illustrated in FIG. 1, the flow of fuel through
the passage 129 to the outlet passage 130 being controlled by a
suitable adjusting key 131 in a conventional manner.
The outlet passage 130 is also interconnected to the intermediate
chamber 115 through an orifice cup 132. In addition, the outlet
passage 130 is interconnected by another orifice cup 133 to a
passage 134 that leads from a filter chamber 135 to the chamber
114. The filter chamber 135 is adapted to be interconnected to the
conduit 31 from the control device 29 as illustrated in FIG. 1
downstream from the safety valve 32.
Therefore, it can be seen that the control device 29 and main valve
means 24 can be formed of relatively few parts in a relatively
simple manner to provide an oven control system 20 as illustrated
in FIG. 1 as well as the oven control systems illustrated in FIGS.
2-4 as will be hereinafter described.
The safety valve 32 for the control system 20 illustrated in FIG. 1
comprises a housing means 136 having an inlet chamber 137
interconnected to the upstream part 138 of the conduit 31 while an
outlet chamber 139 thereof is interconnected to the downstream part
140 of the conduit 31, the chambers 137 and 139 being separated by
a valve seat 141 adapted to be opened and closed by a ball valve
142 normally urged to its closed position by a compression spring
143 in the inlet chamber 137. However, an expansible and
contractible power element 144 is carried by the housing means 136
and has a stem 145 on the movable wall 146 thereof adapted to
project through the valve seat 141 and engage against the ball
valve 142 so that when certain flames exist at the pilot burner
means 27, the detector 33 causes the movable wall 146 of the power
element 144 to move upwardly and thereby move the ball valve member
142 away from the valve seat 141 as long as the flames exist at the
pilot burner 27 so that the upstream part 138 of the conduit 31
will be interconnected with the downstream part 140 thereof.
The detailed operation of the control system 20 of FIG. 1 as well
as the operation of the control device 29 and the main valve member
24 will now be described.
Referring now to FIG. 1, and assuming that the control device 29 is
turned to an off position, fuel is supplied to the pilot burner 27
to maintain a flame at the pilot burner 27 since the conventional
valve 22 in the supply manifold 21 is in an on condition and fuel
can thereby flow through the inlet conduit 25 and passage means 129
and 130 of the main valve means 24 to the conduit 28 leading to the
pilot burner 27. Thus, with flames at the pilot burner 27, the
safety valve 32 has its ball valve member 142 maintained away from
the valve seat 141 so that the conduit means 31 between the control
device 29 and the main valve means 24 is in an open condition.
However, since the control device 29 is in an off condition, the
same is not directing any pneumatic signal through the conduit 30
to the main valve means 24 whereby the chamber 114 is at
substantially atmospheric condition and the intermediate chamber
115 is also at substantially atmospheric condition whereby the
compression spring 128 maintains the diaphragms 112 and 113 in the
position illustrated in FIG. 8 where the ball valve member 123
closes the opening 122 of the tubular extension 118 and maintains
the valve seat 127 of the projection 126 is in an open condition
for interconnecting the passage 129 with the chamber 116 and, thus,
with the chamber 109 through the wall openings 125' so that the
fuel pressure on both sides of the flexible diaphragm 108 are
equal. In this manner, the force of the compression spring 111
maintains the valve member 110 against the valve seat 106 so that
no fuel can flow from the inlet conduit 25 to the outlet conduit 26
and, thus, to the main burner means 23.
However, when the control knob 79 of the control device 29 is moved
from its off position to any selected on cooking position thereof,
the same causes the valve member 78 to unblock the passage 50 and
interconnect the passage 50 to the upstream part 138 of the conduit
31 and at the same time axially adjust the control shaft 80
relative to the housing 37 so that the force of the compression
spring 85 tending to pivot the lever 89 in a clockwise direction
about the pivot point 92 is added to the force of the compression
springs 93 and 45 against the transverse pin 92 of the stem 47 of
the movable wall 48 of the power element 35 so that the temperature
of the oven must increase to the set temperature of the selector
knob 79 in order to cause the power element 35 to expand in
opposition to the force setting of the spring 85 and move the ball
member 44 against the valve seat 43.
However, since the temperature of the oven is normally below the
temperature setting of the knob 79 when the same is first turned to
an on cooking position thereof, the ball valve member 44 is in the
open position as illustrated in FIG. 5 whereby a fuel source
pneumatic signal is adapted to flow from the conduit 30, passage
40, open valve seat 43, and passage 50 into the control signal
conduit 31 and since the safety valve 32 is in an open position,
into the chamber 114 of the main valve means 24 to pressurize the
chamber 114 and thereby cause the diaphragm 113 to move to the left
as illustrated in FIG. 9 carrying therewith the diaphragm 112 until
the ball valve member engages against the valve seat 127. In this
manner, further movement of the ball valve member 123 to the left
is prevented even though the diaphragms 113 and 112 can further
move to the left from the position illustrated in FIG. 9 to the
position illustrated in FIG. 10. As the diaphragms 113 and 112
continue to move to the left from the position illustrated in FIG.
9 to the position illustrated in FIG. 10, it can be seen that the
tubular extension 118 carried by the diaphragm 113 now moves away
from the ball valve member 123 so that the intermediate chamber 116
and, thus, the chamber 109, through the wall openings 125', is now
interconnected to the tubular extension 118 and through the
openings 323 in the tubular extension 118 to the chamber 115 which
is vented to the pilot burner outlet 130 through the orifice cup
132 which has an orifice therein larger than the orifice of the
orifice cup 133. This reduction in pressure on the spring side of
the diaphragm 108 causes the diaphragm 108 to move away from the
valve seat 106 as illustrated in FIG. 10 and since the escape of
gas pressure from the intermediate chamber 116 is increased as the
opening between the ball valve member 123 and valve seat 122
becomes greater, the same results in the diaphragm 108 moving to an
open position at a rapid rate to provide substantially a snap
opening movement thereof whereby fuel is now permitted to flow from
the inlet 104 to the outlet 105 of the main valve means 24 and,
thus, to the burner 23 to be ignited by the pilot burner 27. Thus,
as long as the temperature of the oven is below the temperature
effect setting of the control knob 79, the ball valve 44 of the
control device 29 is in an open position so that the pneumatic
signal is continuously directed to the chamber 114 of the main
valve means 24 to maintain the same in the open position as
illustrated in FIG. 10.
However, when the temperature in the oven reaches or slightly
exceeds the temperature setting of the control knob 79 of the
control device 29, the expansion of the fluid in the temperature
sensing bulb 34 is such that the same has caused the movable wall
48 of the power element 35 to move downwardly in FIG. 5 in
opposition to the force of the compression springs 85, 93 and 45 a
distance sufficient to seat the ball valve member 44 against the
valve seat 43 and thereby terminate the flow of control signal fuel
to the conduit 31 and, thus, to the chamber 114 of the main valve
means 24. Since no more pressure is being directed to the chamber
114 of the main valve means 24, the pressure in the chamber 114
bleeds through the orifice cup 133 to the pilot burner 27. As the
pressure in the chamber 114 is reduced, the diaphragm 113 moves to
the right under the force of the compression spring 128 and
subsequently the valve seat 122 makes contact with the ball valve
123 to carry the same to the right and thereby off of the valve
seat 127. Movement of the ball valve 123 off of the valve seat 127
again permits the chambers 116 and 109 to have fuel under pressure
directed therein by the passage 129 so that the pressure across the
diaphragm 108 subsequently equalizes and the compression spring 111
can again move the diaphragm 108 to its valve closing position as
illustrated in FIG. 8 to terminate the flow of fuel to the main
burner means 23.
Thus, the main control device 29 cycles the control signal to the
main valve means 24 to cause the main valve means 24 to cycle the
main burner means 23 between its off and on conditions to tend to
maintain the temperature in the oven at the temperature selected by
the control knob 79.
If the heat motor means 61 is interconnected to a meat probe or
timer in such a manner that after the oven has been operating at
the selected cooking temperature of the control knob 79 for a
preselected time period or for a preselected meat probe condition
of the food being cooked by the oven, the coil 62 can be
automatically energized to heat the bimetal member 60 and cause the
same to warp to the right as illustrated in FIG. 6 carrying the
latch member 69 therewith which frees the end 90 of the lever 89 so
that the force of the compression spring 85 can now pivot the lever
89 on the transverse pin 92 and engage the end 88 of the lever 89
against the fulcrum point 102 on the housing means 37 so that now
the force of the compression spring 93 is imposed on a long moment
arm of the lever 89 to oppose downward movement of the movable wall
48 of the power element 35 whereby the power element 35 will now
tend to maintain the oven temperature at a warmth retaining and
non-cooking temperature in the manner previously described by
opening and closing the ball valve member 44.
Should the heat motor 61 only be momentarily energized to cause
such rightward movement of the blade 60 and latch member 69 to
provide the keep warm operation of the control device 29, a
rewarping of the blade 60 back to the left even though causing a
closing of the ball valve member 55 against the valve seat 54 will
not effect the operation of the control device 29 as only the
passage 50 is opened by the valve member 78 in any cooking position
of the valve 79 or in the keep warm position thereof.
Of course, if a keep warm temperature is initially selected by the
housewife or the like the heat motor 61 is immediately energized so
that the control device 29 will initially assume the condition
illustrated in FIG. 6.
When it is desired to utilize the oven control system 20 of this
invention for an oven cleaning operation wherein the temperature
effect is to be maintained at a relatively high temperature, such
as 900.degree.F. for burning off the soilage inside the oven, the
control knob 79 of the control device 29 is set in an oven cleaning
position thereof which not only causes the valve member 78 to block
the passage 50 and open the passage 77 to the conduit 31, but also
the control knob 79 has caused the control shaft 80 to be threaded
into the valve block 38 a distance sufficient to cause the
intermediate portion of the lever 90 to bear against the
intermediate portion of the lever 89 as illustrated in FIG. 7 so
that the force of the compression spring 97 will be added to the
lever arrangement 89 in opposing downward movement of the movable
wall 48 of the power element 35.
Also, through a suitable electric switch 78' operated by tying
means 82' operatively interconnected to the control knob 79, the
control knob 79 when set in an oven cleaning position and through
suitable interlocks, such as the locking of the oven door, will
cause the heat motor 61 to be energized so that the bimetal member
60 warps to the right as illustrated in FIG. 7 to unlatch the end
90 of the lever 89 from the latch member 69 whereby the end 88 of
the lever 89 is now acting against the fulcrum point 102 of the
housing means 37. In this manner, the force of the compression
spring 93 and the compression spring 97 as well as the spring 45 is
opposing downward movement of the movable part 48 of the power
element 35. Thus, the heat motor 61 must remain energized during
the entire oven cleaning operation so as to maintain the ball valve
member 55 in the open condition as illustrated in FIG. 7 whereby
the opening and closing of the ball valve member 44 by the power
element 35 will control the main burner 23 in the manner previously
described except that the same will be maintaining a burn-off
cleaning temperature in the oven, the control signal from the
control device 29 to the main valve means 24 being through the open
valve seat 54 and passage 77 under the control of the ball valve
member 44.
When the burn-off cleaning operation is terminated, the energizing
of the heat motor 61 is also terminated and if the control knob 79
has not been turned back to the off position thereof, the lever 69
will tend to move back to the right but will be opposed by the end
90 of the lever 89. However, the bimetal member 60 can warp to the
left to engage against the pin 58 and thereby close the ball valve
member 55 against the seat 54 so that no more fuel can be delivered
to the actuation chamber 114 of the main valve means 24. Thus, the
operation of the main burner 23 is terminated. As the oven cools
down, the end 90 of the lever 89 will cam down along the cam
surface 76 of the latch member 69 to be subsequently received in
the notch 75 thereof and thereby permit the latch member 69 to
assume the position illustrated in FIG. 5 and thereby latch the end
90 of the lever 89 so that the control knob 79 can be utilized to
subsequently set the control device 29 in a cooking position
thereof without requiring a resetting action by the housewife after
an oven cleaning operation.
Therefore, it can be seen that the control device 29 and the main
valve means 24 of this invention can be utilized in the fuel
control system 20 to not only control the burner means 23 for a
cooking and/or keep warm operation thereof, but also for a burn-off
cleaning operation in a simple and effective manner.
However, such control device 29 and main valve means 24 can also be
used in other oven control systems of this invention.
For example, reference is now made to FIG. 2 wherein another
control system of this invention is generally indicated by the
reference numeral 150, the control system 150 including the control
device 29A of this invention and two main valves 24A and 24B
respectively for controlling the flow of fuel from inlet conduit
means 25A and 25B leading from the source conduit 21A respectively
to a bake burner 151 and a broiler burner 152.
Thus, the control system 150 is being utilized for a double burner,
single cavity oven and is adapted to operate either the bake
burner, the broil burner or both the bake burner 151 and broil
burner 152 for an oven clean off operation as will be apparent
hereinafter.
Each main valve 24A and 24B continuously supplies the fuel in the
manner previously described to the pilot burner means 27A and 27B
respectively utilized for the burners 151 and 152, safety valves
32A and 32B being respectively provided in control signal conduits
31A and 31B leading from the control device 29A to the operating
chambers 114A and 114B of the main valve means 24A and 24B.
The valve member 78A for the control device 29A is so constructed
and arranged that when the control knob (not shown) of the control
device 29A is set for a baking operation, only the outlet 50A of
the control device 29A is interconnected to the conduit 31A whereby
the main valve means 24A will operate the bake burner 151 in the
manner previously described to maintain a selected baking
temperature effect in the oven. When the valve member 78A is set in
a broil position, only the outlet 50A of the control device 29A is
interconnected to the conduit 31B whereby the main valve means 24B
controls the broil burner 152 in the manner previously
described.
When the control knob of the control device 29A is set in an oven
cleaning position, the valve member 78A is so constructed and
arranged that the same only interconnects the outlet 77A to both
conduits 31A and 31B so that both the bake burner 151 and broil
burner 152 will be operated to produce the self cleaning
temperature effect by the control device 29A as previously
described.
Another oven control system of this invention is generally
indicated by the reference numeral 153 in FIG. 3 and also comprises
a single control device 29C and two main valve means 24C and 24D
respectively controlling the flow of fuel to a bake burner 151C and
to a broil burner 152D in a manner substantially similar to the
control system 150 previously described when the control device 29C
is being utilized for a baking or broiling operation.
However, for a cleaning operation of the control system 153, the
valve member 78C is so constructed and arranged that when the same
is set in an oven cleaning position thereof, the same interconnects
the outlet 77C to the control signal conduit 31D for operating the
broil burner 152D in the manner previously described and also
interconnects the outlet 77C to a control signal conduit 154 that
leads to a temperature responsive valve means 155 that has an
outlet 156 interconnected to the control signal conduit 31C for the
bake burner valve means 24C in advance of the safety valve 32C
thereof.
The temperature responsive valve 155 comprises a housing 157 having
two spaced valve seats 158 and 159 having a movable ball valve
member 160 disposed therebetween and normally urged to the left in
a closed position against the valve seat 158 by a compression
spring 160'. A temperature responsive power element 161 is provided
with a stem 163 adapted to project through the valve seat 158 and
engage the ball valve member 160, the power element 161 being
interconnected by a capillary tube 262 to a temperature sensing
bulb 263 that senses the temperature in the oven.
The temperature responsive valve means 155 is so constructed and
arranged that when the control device 29C is set for a burn off
cleaning operation, the ball valve member 160 remains in its closed
position against the valve seat 158 until the operation of the
broil burner 152D under the control of the control device 29C has
raised the temperature of the oven to a predetermined temperature
that is below the desired burn off cleaning temperature. When the
predetermined temperature is reached, the power element 161 has
moved the ball valve member 160 intermediate the valve seats 158
and 159 so that the control signal from the control device 29C will
now be directed to the valve means 24C for operating the bake
burner 151C simultaneously with the broil burner 151D. However,
when the temperature in the oven subsequently reaches the
predetermined clean off temperature, the power element 161 of the
valve means 155 has expanded in such a manner that the same will
close the ball valve member 160 against the valve seat 159 and
thereby terminate the operation of the bake burner 151C. Thus, the
temperature responsive valve 155 will cycle the bake burner 151C
between its off and on conditions to tend to maintain the oven at
the burn off cleaning temperature as the broil burner 152D will be
continuously operated during the oven cleaning cycle.
However, during a runaway condition of the oven above the cleaning
temperature, the control device 29C will terminate the flow of fuel
to the outlet 77C thereof by the ball valve member 55C in the
manner previously described whereby the thermostatic device 29C
will act as a high limit should the valve means 155 fail.
Another oven control system of this invention is generally
indicated by the reference numeral 164 in FIG. 4 and is
substantially identical to the control system 153 previously
described except that such control system 164 is for a "muffle
type" oven wherein an air supply means 165 must be continuously
operating during the use of the bake burner 151E and/or use of the
broil burner 152F.
The passage 129E of the main valve means 24E is directly
interconnected to the conduit 28E leading to the pilot burner 27E
for the bake burner 151E whereas the passage 130E of the valve
means 24E is interconnected to a conduit 165E that leads to another
small burner 166E adjacent the pilot burner 27E so that if any fuel
issues from the burner 166E in the manner hereinafter described,
the same will be ignited by the continuously burning pilot burner
27E.
Similarly, the main valve means 24F for the broil burner 152F has
its passage 130F interconnected to a conduit 165F that leads to a
small burner 166F disposed adjacent the pilot burner 27F for the
broil burner 152F. However, the pilot burner 27F for the broil
burner 152F is interconnected by a conduit 167 to the valve means
78F of the control device 29F.
The main control device 29F is similar to the control device 29
previously described except that the heat motor means 61F thereof
is only utilized for modifying the lever arrangement therein when
energized in the manner previously described as no ball valve
equivalent to the ball valve 55 is provided in the thermostatic
device 29F.
A pair of air sensing valves 168E and 168F are provided
respectively for the burners 151E and 152F, each air sensing valve
168E and 168F comprising a housing means 169 having a flexible
diaphragm 170 dividing the same into two chambers 171 and 172 with
the chamber 172 being interconnected to a branch conduit 173 by a
valve seat 174 adapted to be opened and closed by a ball valve
member 175 carried by the diaphragm 170 and normally being urged in
an open position by a compression spring 176. However, the chamber
171 of each air sensor 168E and 168F is interconnected to a conduit
means 177 interconnected to the outlet 178 of the air supply 165 so
that when the air supply is operating, the same pressurizes the
chambers 171 to cause the diaphragms 170 to move the ball valve
members 175 fully against the valve seats 174 in the manner
illustrated in FIG. 4.
The pneumatic control signal conduits 31E and 31F respectively have
the safety valves 32E and 32F therein except that the downstream
parts 140E and 140F thereon have branch conduits 179E and 179F
respectively leading to the chambers 172 of the air sensors 168E
and 168F. The branch conduits 173 of the air sensors 168E and 168F
are respectively interconnected to the conduits 165E and 165F that
lead to the auxiliary burners 166E and 166F for a purpose now to be
described.
Should pneumatic signals be directed through the conduits 31E and
31F toward the main valve means 24E and 24F and the air supply 165
not be operating, then the ball valve members 175 of the air
sensors 168E and 168F will be in an open position so that the
pneumatic signal passing through the open safety valves 32E and 32F
will be diverted through the air sensors 168E and 168F to the
burners 166E and 166F to be ignited and burn without causing
opening of the main valves 24E and 24F. However, should the air
supply 165 be operating, then the ball valve members 175 will be
closed against the valve seats 174 in the air sensors 168E and 168F
so that the control signal will only be directed to the main valves
24E and 24F to open the same in the manner previously
described.
The outlet 50F of the control device 29F in combination with the
valve member 78F is so constructed and arranged that when the valve
member 78F is set in a broiling or oven cleaning position, the
inlet 40F from the supply conduit 25F is directly connected to the
conduit 167 leading to the pilot burner 27F for the broil burner
152F with the control device 29F operating suitable ignition means
(not shown) for igniting the pilot burner 27F. Also, when the valve
member 78F is set in a baking position, the outlet 50F is directly
connected to the conduit 31E to operate the bake burner 151E in the
manner previously described.
However, the valve member 78F also controls the interconnection to
two conduit means 180 and 181 so that when the valve member 78F is
set in a broiling or self cleaning position, the outlet 50F is
interconnected to the conduit 180 and when the valve member 78F is
set in an oven cleaning position, the valve member 78F
interconnects the conduit 181 to the conduit 31E.
The conduits 180 and 181 are also interconnected to a temperature
responsive valve 155F similar to the valve 155 of FIG. 3 except
that the conduit 180 is interconnected to the spacing between the
valve seats 158F and 159F with the conduit 181 being interconnected
to the left of the valve seat 158F and the conduit 31F being
interconnected to the right of the valve seat 159F.
Thus, it can be seen that when the valve member 78F of the control
device 29F is set for a broiling operation, the control signal can
be directed from the outlet 50F into the conduit 180 and pass
through the open valve seat 159F of the valve 155F to control the
broil burner 152F in the manner previously described because the
ball valve member 160F is not moved against the valve seat 159F
until the temperature in the oven exceeds an oven cleaning
temperature.
When the valve member 78F of the device 29F is set for an oven
cleaning operation, the pneumatic signal from the outlet 50F is
directed to the conduit 180 to operate the broil burner 152F in the
manner previously described while the conduit 181 is interconnected
to the conduit 31E for the bake burner 151E. However, initially the
oven is below a predetermined high temperature in the oven so that
the ball valve member 160F prevents any pneumatic signal from being
directed to the conduit 181 and, thus, to the conduit 31E for the
bake burner 151E so that the broil burner 152F is initially
operated during the cleaning operation. However, when the
temperature in the oven exceeds a predetermined high temperature
therein, the ball valve member 160F is moved intermediate the valve
seats 158F and 159F so as to continuously operate the broil burner
152F and to also now turn on the bake burner 151E so that both
burners 151E and 152F are utilized to raise the temperature to the
self cleaning temperature. However, as the temperature in the oven
exceeds the self cleaning temperature, the ball valve member 160F
can close the valve seat 159F and, thus, terminate the operation of
the broil burner 152F so that the ball valve member 160F will cycle
the broil burner 152F on and off while continuously maintaining the
bake burner 151E on to maintain a self cleaning temperature in the
oven, the control device 29F acting as a high limit for a runaway
condition during the oven cleaning operation in the manner
previously described for the control system 153.
Therefore, it can be seen that the control device 29 and main valve
member 24 of this invention can be utilized in various combinations
to provide different oven control systems as previously
described.
While the valve means 24 previously described can have the
configuration previously described in connection with FIG. 8,
another embodiment thereof is described indicated by the reference
numeral 200 in FIGS. 11 and 12 and will now be described.
As illustrated in FIGS. 11 and 12, the valve means 200 comprises a
housing means 201 carrying three flexible diaphragms 202, 203 and
204 respectively defining chambers 205, 206 and 207 with the
housing means 201. The diaphragm 204 carries a valve member 208 for
opening and closing a valve seat 209 which separates an inlet 210
from an outlet 211. The diaphragm 202 is interconnected to a
tubular extension 212 of the diaphragm 203 by a spider-like member
213 which fluidly interconnects the open end 214 of the tubular
extension 212 to the intermediate chamber 206. The diaphragm 203
carries a valve seat 215 inside the tubular extension 212 which is
adapted to be opened and closed by a valve member 216 carried by
the diaphragm 202 normally being urged to a closed position by a
compression spring 217.
The housing 201 has a tubular extension 218 extending into the
valve seat 215 and defining a valve seat 219 at the open end
thereof with the valve seat 219 being interconnected to the inlet
210 by as passage 220. The inlet 210 is also interconnected by a
passage 221 to an outlet 222 that is adapted to be directed to a
pilot burner for supplying a continuous fuel flow thereto in the
same manner as the passage 129 of the valve means 24.
The diaphragm 203 cooperates with the housing to define a chamber
223 that is interconnected by a passage 224 to the chamber 207 for
the diaphragm 204. Thus, as long as the valve member 216 is held
away from the valve seat 219 in the manner illustrated in FIG. 11,
fuel from the inlet 210 is adapted to pass through the passage 220,
open valve seat 219, chamber 223 and passage 224 to the chamber 207
for the diaphragm 204 so that the diaphragm 204 in combination with
a compression spring 225 will maintain the valve member 208 against
the valve seat 209 in the same manner as provided by the diaphragm
108 of the valve means 24.
The control pneumatic signal for operating the valve means 200 is
adapted to enter an inlet passage 226 that is interconnected to the
intermediate chamber 206 by an orifice cup 227 and directly into
the actuating chamber 205 by a branch passage 228. The intermediate
chamber 206 is also interconnected to the pilot passage 221 by an
orifice cup 229.
Therefore, it can be seen that the valve means 200 operates in the
same manner as the valve means 24 previously described because when
a pneumatic signal is directed to the inlet 226, the same
pressurizes the chamber 205 to move the diaphragm 202 downwardly
and carry the diaphragm 203 therewith so that the tubular extension
218 of the housing 201 will be engaged by the valve member 216 to
close off the inlet 210 from the intermediate chamber 223 and
further downward movement of the diaphragms 202 and 203 cause the
valve seat 215 to move away from the valve member 216 in the manner
illustrated in FIG. 12 so that the chamber 223 and, thus, the
chamber 207 is vented to the chamber 206 which is interconnected to
the pilot passage 221 by the orifice cup 229 whereby the pressure
differential across the diaphragm 204 increases and the inlet
pressure can cause the same to move to an open position as
illustrated in FIG. 12 in the same manner as provided by the valve
means 24.
Therefore, it can be seen that modifications can be made in the
various control devices of this invention with the operation
thereof occurring in the same manner to accomplish the desired
functions as previously described in connection with the oven
control system.
Thus, this invention provides improved oven control systems.
While the form of the invention now preferred has been described as
required by the statutes, variations can be made therein and all
coming within the scope of the claims which follow.
* * * * *