US3312396A - Double burner oven control system - Google Patents

Description

April 4, 1967 J. R. WILLSON DOUBLE BURNER OVEN CONTROL SYSTEM 5 Sheets-Sheet 1 Filed July 22, 1964 INVENTOR. JAMES R. WILLSON HIS ATTORNEYS April 4, 1967 J. R. WILLSON 3,312,396

DOUBLE BURNER OVEN CONTROL SYSTEM Filed July 22, 1964 Z Sheets-Sheet 2 F 2 INVENTOR.

JAMES R. WILLSON WM; M

HIS ATTORNEYS April 4, 1967 J. R. WILLSON DOUBLE BURNER OVEN CONTROL SYSTEM 5 Sheets-Sheet 5 Filed July 22, 1964 I INVENTOR. JAMES R- WILLSON HIS ATTORNEYS United States Patent C) 3,312,396 DOUBLE BURNER OVEN CONTROL SYSTEM James R. Willson, Greensburg, Pa., assignor to Robertshaw Controls Company, Richmond, Va., a corporation of Delaware Filed July 22, 1964, Ser. No. 384,437 12 Claims. (Cl. 236-15) This invention relates to an improved control system for a double burner oven or the like.

It is well known that various manufacturers have been striving to provide a double burner oven system wherein the lower burner in the oven is utilized for baking purposes and the like and the upper burner means is utilized for broiling purposes and the like.

However, some means must be provided for permitting the user of the oven to select the desired operation of the particular burner means of such a double burner oven or the like.

According to the teachings of this invention, improved control means are provided for selectively operating the burners in a double burner oven or the like.

Accordingly, it is an object of this invention to provide 9 an improved control system for a double burner or the like, the system of this invention having one or more of the novel feautres 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:

FIGURE 1 is a schematic view illustrating the im proved control system of this invention.

, FIGURE 2 is an enlarged, fragmentary, cross-sectional view of one of the parts illustrated in FIGURE 1.

FIGURE 3 is a view similar to FIGURE 2 and illustrates another part of the system illustrated in FIGURE 1.

FIGURE 4 is also a view similar to FIGURE 2 and illustrates another part of the apparatus illustrated in FIGURE 1.

FIGURE 5 is an enlarged, fragmentary, cross-sectional view taken on line 55 of FIGURE 1.

FIGURE 6 is a view similar to FIGURE 5 and illustrates the selector valve in another operating position thereof.

FIGURE 7 is.also a view similar to FIGURE 5 and illustrates the selector valve in another operating position thereof.

While the various features of this invention are hereinafter shown and described as being particularly adaptable for providing a control system for a double burner oven or the like, it is to be understood that the various features of this invention can be utilized singly or in any combination thereof to provide a control system 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 one of the wide variety of uses of this invention.

Referring now to FIGURE 1, the improved fuel control system and method of this invention is generally indicated by the reference numeral 10 and is utilized for controlling the operation of a double burner oven generally indicated by the reference numeral 11.

A bake burner tmeans12 is disposed in the lower portion of the oven 11 and a broil burner means 13 is provided in the upper end of the oven 11.

A source of fuel, such as gas or the like, is provided by a manifold 14 and is adapted to be selectively interconnected to the bake burner means 12 and broil burner means 14 by a, manually operated selector valve 15.

The selector valve 15 includes a housing 15 suitably fixed to the oven 11 so that a selector knob 17 will project outwardly from a control panel of the oven 11 and be adapted to rotate a plug valve 18 disposed in the housing 16, the plug valve 18 having a central bore 19 interconnected to a conduit means 20 leading from the manifold 14 to the selector valve 15.

The plug valve 18 has a pair of transverse bores 21 and 22 respectively interconnecting the central bore 19 thereof with the outer peripheral surface of the plug valve 18.

The housing 16 has a plurality of ports 23, 24 and 25 formed therein and leading from the plug valve 18 respec tively to conduits 26, 27 and 28 for purposes hereinafter described. When the selector knob 17 of the selector valve 15 is disposed in the position illustrated in FIGURE 5, it can be seen that no fuel is adapted to flow through the selector valve 15 to the conduits 26-28.

However, when the selector knob 17 of the selector valve 15 is disposed in its bake position as illustrated in FIGURE 6, fuel is adapted to flow through the selector valve 15 to the conduit 26 for baking purposes in a manner hereinafter described. Similarly, when the selector knob 17 of the selector valve 15 is disposed in its broil position as illustrated in FIGURE 7, fuel is only adapted to flow through the selector valve 15 to the conduits 27 and 28 for broiling purposes in a manner hereinafter described.

A high limit theormostatic valve 29, FIGURE 1, is disposed in the conduit 20 and restricts the interconnection of the source of fuel 14 with the selector valve 15 should the temperature effect of the oven 11 approach a broiling temperature effect.

In particular, the thermostatic valve 29 includes a housing 39 provided with a valve seat 31 interconnecting the inlet side 32 thereof with the outlet side 33 thereof. A valve member 34 is utilized for opening and closing the valve seat 31, the valve member 34 normally being urged to the open position by a compression spring 35 and being interconnected to a movable Wall 36 of an expansible and contractable element 37, the element 37 having another wall 38 fixed to the housing 30.

The interior of the element 37 is interconnected to a temperature sensing bulb 39 disposed in the oven 11 in any suitable position thereof by a conduit means 40.

Thus, as long as the oven 11 has a temperature therein below the temperature exceeding the broil temperature of the oven 11, the valve member 34 remains in the open position thereof as illustrated in FIGURE 1. However, should the temperature effect of the oven 11 exceed a broiling temperature effect thereof whether the oven is being operated with the bake burner 12 or the broil burner 13, the element 37 expands and closes the valve member 34 against the valve seat 31 to terminate the flow of fuel from the source 14 to the selector valve 15 whereby neither burner 12 or 13 can be operated until the temperature of the oven 11 falls below the high limit setting of the valve 29 whereby the high limit thermostatic valve 29 provides a safety feature of this invention.

The conduit 26 leading from the selector valve 15 is interconnected to the inlet side 41 of an automatic safety valve42 having the outlet side 43 thereof interconnected to the bake burner 12 by a conduit 44.

In particular, reference is now made to FIGURE 2 wherein it can be seen that the safety valve 42 includes a housing 45 having the inlet chamber 41 thereof interconnected to the outlet chamber 43 thereof by a valve seat 46 opened and closed by a movable valve member 47.

The valve member 47 is moved between its opened and closed positions by a snap spring 48 operated by lever means 49 interconnected to a movable wall 56 of an expansible and contractible element 51, the element 51 having a wall 52 fixed to the housing 45 and having the interior thereof interconnected to a temperature sensing bulb 53 by a conduit 54.

The temperature sensing bulb 53 is so constructed,

and arranged that the same is adapted to sense when a flame appears ata controller pilot 55 in a manner hereinafter described.

Thus, when a flame appears at the controller pilot 55, the temperature sensing bulb 53 senses the same and causes the element 51 to expand whereby the valve member 47 is moved to an opened position to permit theflow of fuel from the selector valve 15 to pass through the automatic valve 42 to the bake burner 12. However, when a flame ceases to exist at the controller pilot 55, the element 51 contracts to permit the snap spring 48 to snap the valve member 47 to its closed position so that no fuel can flow to the bake burner 12.

While the particular details of the automatic valve 42 does not form a per se part of this invention, it is deemed only necessary to state that the automatic valve 42 only interconnects the conduit 26 With the conduit 44 when a flame exists at the controller pilot 55 and prevents communication between the conduits 26 and 44 when a flame ceases to exist at the controller pilot 55.

However, for further details of the structure and opera tion of the automatic valve 42, attention is directed to the co-pending patent application, No. 202,780, filed June 15, 1962, now Patent No. 3,233,830.

In order to ignite fuel issuing from the controller pilot 55, a standby pilot 56 is provided and is continuously fed fuel from the manifold 14 by a conduit 57. Thus, once the standby pilot 56 has been ignited, the same continues to have a flame regardless of the operation of the controller pilot 55 in a manner hereinafter described.

The controller pilot 55 is adapted to be fed fuel from a conduit 57 leading from an outlet side of a thermostatic valve 58 50 mounted relative to the oven 11 that a selector knob 59 thereof is disposed at the control panel or the like of the oven 11. The inlet side of the thermostatic valve 58 is interconnected to the manifold 14 by a conduit 66.

Referring now to FIGURE 3, the thermostatic valve 58 includes a housing means 61 having an inlet chamber 62 interconnected to the conduit and an outlet chamber 63 interconnected to the conduit 57, the inlet chamber 62 and the outlet chamber 63 being interconnected together by a valve seat 64 opened and closed by a valve member 65.

The valve member 65 is normally urged to the closed position by a compression spring 66 and has a stem 67 extending therefrom and engaging an end 68 of a lever 69 fulcrurned for pivotal movement on an axially movable stem 70, the position of the stem 70 being controlled by the position of the selector knob 59'which has an off position and desired temperature range positions.

The lever, 69 has the other end '71 thereof normally urged in a clockwise direction by a leaf spring 72. However, the end 71 of the lever 69 bears against a movable wall 73 of an expansible and contractible element 74 having a wall 75 fixed to the housing means 61. The interior of the element 74 is interconnected to a temperature sensing bulb 76 by a conduit means 77 for a purpose hereinafter described.

When the control knob 59 is disposed in its off position,

the axially moving stem 70 is moved to such a position that regardless of the temperature of the oven 11, the valve member 65 is disposed in its closed position.

However, when the control knob 59 is moved to a temperature setting position thereof and the oven 11 has a temperature below that particular temperature, the spring 72 causes the valve member 65 to open in opposition to the force of the compression spring 66 whereby the manifold 14 is interconnected to the controller pilot 55 so that the fuel issuing from the controller pilot 55 can be ignited by the standby pilot 56.

Thus, the valve member 65 of the thermostatic valve 58 remains open as long as the temperature of the oven 11 is below the temperature selected by the control knob 59 thereof.

However, should the temperature of the oven 11 exceed the temperature selected by the control knob 59, the expansible element 74 has expanded to such an extent that the same pivots the lever 69 in such a manner that the valve member 65 is adapted to seat against the valve seat 64 and terminate the flow of fuel to the controller pilot 55 whereby the controller pilot 55 goes out.

When the temperature of the oven 11 again falls below the selected temperature, the element 74 has contracted to such an extent that the lever 69 is adapted to again open the valve member 65 to interconnect the source of fuel 14 with the controller pilot 55.

Therefore, it can be seen that the thermostatic valve 58 is adapted to cycle the flow of fuel to the controller pilot 55 in such a manner that when the temperature of the oven 11 is below a selected temperature, a flame ap pears at the controller pilot 55 and when the temperature of the oven 11 is above the selected temperature, no flame appears at the controller pilot 55.

For further details of the structure and operation of the thermostatic valve, see the copending patent apprication Ser. No. 416,184, filed Nov. 23, 1964.

The conduit 27 is interconnected to the inlet side 78 of an automatic safety valve 79, the outlet side of the automatic valve 79 being interconnected to the broil burner 13 by a conduit 81'.

As illustrated in FIGURE 4, the automatic valve 79 has the inlet chamber 78 thereof interconnected to the outlet chamber 80 by a valve seat 81 opened and closed'by a valve member 82 normally urged to the closed position by a compression spring 83.

An expansible element 84 is disposed in the housing 85 of the automatic valve 79 and has a movable wall 85 and a fixed wall 86, the interior of the element 84 being interconnected to a temperature sensing bulb 87 by a conduit means 88. The movable wall 85 of the element 84 is adapted to bear against a lever 89 fulcrumed at point 90 whereby the end 91 of the lever 89 is adapted to bear against an end 92 of a lever 93 fulcrumed at a point 94.

The other end 95 of the lever 93 is adapted to bear against the valve member 82 and move the same to an open position in opposition to the force of the compression spring 83 when the element 84 expands because the temperature sensing bulb 87 is sensing that a flame exists at a controller pilot 96.

However, the valve member 82 closes against the valve seat 81 when the temperature sensing bulb 87 senses that no flame exists at the controller pilot 96.

The housing 85 of the automatic valve 79 includes an auxiliary inlet chamber 97 interconnected to an auxiliary outlet chamber 98 by a valve seat 99, the valve seat 99 being opened and closed by a valve member 100 normally urged to the open position by a compression spring 101. However, the valve member 99 carries a stem 102 engageable by the end 95 of the lever 93 so that when the lever 93 is in a position to permit the valve member 82 to seat against the valve seat 81, the auxiliary valve member 100 is also seated against its valve seat 99.

However, when the lever 93 moves to open the valve member 82, the same simultaneously permits the valve member 100 to open, the valve member 100 when in the open position seals the opening through which the valve stem 102 projects.

Therefore each time the valve member 82 is opened, the valve member 100 is also opened and, conversely, when the valve member 82 is closed, the valve member 100 is closed for a purpose hereinafter described.

For further details of the structure and operation of the automatic valve 79, see the co-pending patent application, Ser. No. 763,892, filed Sept. 29, 1958, now Patent No. 3,213,922.

The auxiliary inet chamber 97 of the automatic valve 79 is interconnected to the manifold 14 by a conduit 103. The auxiliary outlet chamber 98 of the automatic valve 79 is interconnected to a standby pilot 104 by the conduit 105.

In this manner, the standby pilot 104 has fuel issuing therefrom every time the automatic valve 79 is opened in response to the presense of the flame at the controller pilot 96.

An electrical ignition coil 106 is disposed adjacent the controller pilot 96 and the standby pilot 104 for igniting the same when the ignition coil 106 is energized, the ignition coil 106 being interconnected to the secondary winding 107 of a transformer 108. The primary winding 109 of the transformer 108 has one side thereof interconnected to a power source lead L by a lead 110.

The other side of the primary winding 109 of the transformer 108 is interconnected to a fixed contact 111 of a pressure responsive electrical switch 112 by a lead 113. The other fixed contact 114 of the switch 112 is interconnected to the other ower lead L by a lead 115.

The pressure responsive switch 112 inciudes a housing 116 divided into two chambers 117 and 118 by a flexible diaphragm 119 carrying a contact 120 adapted to bridge the fixed contacts 111 and 113 when the diaphragm 119 is moved upwardly in a manner now to be described.

The chamber 118 of the switch 112 is interconnected I to the inlet chamber 78 of the automatic valve 79 by a conduit 121 while the chamber 117 of the switch 112 is interconnected to the outlet chamber 80 by a conduit 122.

In this manner, when the fuel is initially directed to the automatic valve 79 by the selector valve in a manner hereinafter described, the fuel pressure in the inlet chamber 78 of the automatic valve 79 builds up because the valve member 82 is in the closed position. This buildup of pressure in the inlet chamber 78 of the automatic valve 79 builds up in the chamber 118 of the switch 112 and causes the diaphragm 119 to move upwardly and bridge the contacts 111 and 114 with the contact 120 whereby current is-adapted to flow through the transformer 108 and cause the ignition coil 106 to ignite fuel issuing from the controller pilot 96, the controller pilot 96 being sup- [plied fuel simultaneously with the supplying of fuel to the automatic valve 79 because the selector valve 15 isdisposed in the position illustrated in FIGURE 7.

When a flame appears at the controller pilot 96, the

temperature sensing bulb 87 senses the presence of the same and causes the valve members 82 and 100to move to the opened positions whereby fuel is adapted to now issue from the broil burner 13 to be ignited by the controller pilot 96. However, since the inlet chamber 78 and outlet chamber 80 have the pressures thereof equalized when the valve member 82 is moved to the open position, it can be seen that the diaphragm 119 will return to the position illustrated in FIGURE 1 and, thus, terminate the operation of the ignition coil 106.

When the valve member 82 opens, the auxiliary valve member 100 of the automatic valve 79 also opens to interconnect the source of fuel 14 with the standby pilot 104 whereby the fuel issuing from the standby pilot 104 is ignited by the flame at the control pilot 96.

T he operation of the control system 10 of this invention will now be described.

Assuming that the standby pilot 56 has been ignited and that the user of the oven 11 desires to operate the same with the bake burner 12, the operator turns the selector knob 17 of the selector valve 15 to its bake position as illustrated in FIGURE 6 and turns the selector knob 59 of the thermostatic valve 58 to the desired temperature setting thereof.

Thus, it can be seen that the valve member 65 of the thermostatic valve 58 is moved to an open position thereof whereby fuel is adapted to issue from the controller pilot 55 and be ignited by the standby pilot 56. Once a flame appears at the controller pilot 55, the temperature sensing bulb 53 of the automatic valve 42 senses the presence of the flame at the controller pilot 55 and opens the valve member 47 thereof to interconnect the selector valve 15 with the bake burner 12 whereby the fuel now issuing from the bake burner 12 is ignited by the controller pilot 55.

The automatic valve 42 remains in the open position as long as the temperature of the oven 11 remains below the selected temperature. However, should the temperature of the oven 11 exceed the selected temperature thereof, the valve member 65 of the thermostatic valve 58 moves to the closed position to terminate the flow of fuel to the controller pilot 55.

When the flame ceases to exist at the controller pilot 55, the automatic valve 42 closes to prevent fuel from issuing from the bake burner 12. Thus, the bake burner '12 has the operation thereof terminated until the tem- 11 at the temperature selected by the selector knob 59 of the thermostatic valve 58.

When the operator of the oven 11 desires to operate the same with the broil burner 13, the operator turns the selector valve 15 to the broil position thereof as illustrated in FIGURE 7 whereby the conduits 27 and 28 are respectively interconnected to the conduit 20 by the selector valve 15.

Since the safety valve 79 is in the closed position fuel is directed thereto by the conduit 27, the pressure switch 112 closes in the above manner whereby the ignition coil 106 is energized and ignites the fuel now issuing from the controller pilot 96 by means of the opened conduit 28.

When a flame appears at the controller ilot 96, the temperature sensing bulb 87 of the valve means 79 senses the presence of the flame at the controller pilot 96 and simultaneously opens the valve members 82 and whereby fuel can be passed through the opened valve seat 81 to the broil burner 13 and be ignited by the controller pilot 96.

Simultaneously, fuel is passed through the open valve seat 99 and issues from the standby pilot burner 104 to be ignited by the controller pilot 96.

With the opening of the valve member 82 of the safety valve 79, the pressure switch 112 is returned to its normally opened position to terminate the energization of the ignition coil 106.

Thus, the broil burner 13 continues to operate during the entire broil setting of the selector valve 15.

Should the temperature effect of the oven 11 exceed the desired broiling temperature efliect, the sensing bulb 39 causes the element 37 of the high limit thermostatic valve 29 to expand whereby the valve member 34 is progressively moved'toward the seat 31 to throttle down the maintain a reduced, but continuous, flame at the broil burner 13 throughout the broiling operation without the termination or closing of the safety valve 7 9.

In one setting of the system of this invention, if the valve member 34 of the high limit thermostatic valve 29 were to throttle too close to the valve seat 31, due to bad calibration or other reasons, the controller pilot flame at the controller pilot 96 would probably reduce in size to the point where the safety valve 79 would close before the high limitthermostatic-valve 29 would close completely. As quickly as the automatic valve 79 would close, pressure would build up in the line 2! downstream from the high. limit thermostatic valve 29 due to the fact that the high limit thermostatic valve 29 is nearly closed. The increased pressure in the conduit 20 downstream from the'high limit thermostatic valve 29 would then start a recycling of the automatic safety valve 79 and, this re-cycling, would persist until such time as the high limit thermostatic valve 29 is either tightly closed or more wide open.

Since one of the objectives of this invention is to provide a continuous flame broiling operation, the high limit thermostatic valve 29 is carefully calibrated to the desired broil temperature which in one setting of the system of this invention is about 625 F. Due to the rate of gas required to maintain the 625 F. temperature in the oven 11, the fiame at the controller pilot burner 96 will not be reduced to the point where the automatic valve 79 would close.

Thus, it can be seen that either during the broiling op eration or the baking operation of the oven 11 of this invention, the high limit thermostatic valve 29 will prevent the temperature of the oven 11 from exceeding a broiling temperature effect thereof.

Should the housewife be utilizing the oven 11 in a broiling operation in the above manner, and rapidly move the selector knob 17 of the selector valve from its broil position to another position thereof and then back to the broil position before the automatic valve 79 moves to its closed position, item be seen the fuel would be adapted to issue from the bro-i1 burner 13 as well as from the standby pilot 10 because of the opened valve members 82 and 1% whereby a flame will always be at the standby pilot burner 104 to re-ignite the fuel issuing from I the broil burner 13 as well as from the controller pilot $5.

follow.

What is claimed is:

1. In combination, a bake burner means, a broil burner means, a source of fuel, a selector valve, first means interconnecting said source of fuel with said selector valve, a

' preset high limit thermostatic valve in said first means to prevent communication between said source of fuel and said selector valve only when the temperature effect of said burner means exceeds 'a broiling temperature effect,

:second means interconnecting said selector valve with 7 "high limit thermostatic valve is open.

2. A combination as set forth in claim 1 wherein said "high limit thermostatic valve includes an expansible element.

3. In combination, a bake burner means, controller ,pilot means for said bake burner means, a broil burner means, a source of fuel, a selector valve, first means interconnecting said source of fuel with said selector valve, a preset high limit thermostatic valve in said first means to prevent communication between said source of fuel and said selector valve only when the temperature effect of said burner means exceeds a broiling temperature effect, second means interconnecting said selector valve with said bake burner means so that the baking temperature effect of said bake burner can be thermostatically controlled independently of the operation of said high limit thermostatic valve, an automatic valverdisposed in said second means and being responsive to a flame at said controller pilot means to interconnect said selector valve to said bake burner means, third means interconnecting said selector valve with said broil burner means whereby said selector valve can selectively direct fuel to either said bake burner means or said broil burner means only when said high limit thermostatic valve is open, and fourth means interconnecting said source of fuel with said controller pilot means.

4. A combination as set forth in claim 3 wherein a standby pilot means is provided to ignite fuel issuing from said controller pilot means, and wherein means interconnect said source of fuel with said standby pilot means at all times.

5. A combination as set forth in claim 3 wherein said high limit thermostatic valve includes an expansible ele ment.

6. In combination, a bake burner means, controller pilot means for said bake burner means, a broil burner means, a source of fuel, a selector valve, first means in terconnecting said source of fuel with said selector valve, a high limit thermostatic valve in said first means to pre vent communication between said source of fuel and said selector valve only when the temperature effect of said burner means exceedsa broiling temperature effect, second means interconnecting said selector valve with said bake burner means, an automatic valve disposed in said second means and being responsive to a flame at said controller pilot means to interconnect said selector valve to said bake burnei" means, third means interconnecting said selector valve with said broil burner means whereby said selector valve can selectively direct fuel to either said bake burner means or said broil burner means only when said high limit thermostatic valve is open, fourth means interconnecting said source of fuel with said controller pilot means, and a temperature responsive valve disposed in said fourth means to interconnect said source of fuel to said controller pilot means in response to a temperature setting of said temperature responsive valve.

7. A combination as set forth in claim 6 wherein said temperature responsive valve has an OFF position.

8. In combination, a bake burner means, a broil burner means, broil pilot burner means, a source of fuel, a selector valve, first means interconnecting said source of fuel with said selector valve, a high limit thermostatic ,valve in said first means to prevent communication between said source of fuel and said selector valve only when the temperature effect of said burner means exceeds a broiling temperature effect, second means interconnecting said selector valve with said bake burner means, third means interconnecting said selector valve with broil burner means whereby said selector valve can selectively direct fuel to either said bake burner means or said broil burner means only when said high limit thermostatic valve is open, and an automatic valve disposed in said third means and being responsive to a flame at said broil pilot means to interconnect said selector valve with said broil burner.

9. A combination as set forth in claim 8 wherein an electrical ignition system is provided for said broil pilot means, and wherein said automatic valve actuates said ignition system before the same interconnects said selector valve with said broil burner means.

10. A combination as set forth in claim 8 wherein a standby pilot burner is provided for said broil burner,

and wherein said automatic valve interconnects said standby pilot burner with said source of fuel when said automatic valve interconnects said selector valve with said broil burner means.

11. A combination as set forth in claim 8 wherein fourth means interconnects said source of fuel with said broil pilot burner means.

12. A combination as set forth in claim 11 wherein said selector valve controls said fourth means.

ALDEN D.

References Cited by the Examiner UNITED STATES PATENTS 4/1950 Andersson 23615 5/1953 Hollman 158-133 5/ 1957 Hollman et a1. 12639 6/1964 Jackson et a1 l58-l43 STEWART, Primary Examiner.

Claims (1)

1. IN COMBINATION, A BAKE BURNER MEANS, A BROIL BURNER MEANS, A SOURCE OF FUEL, A SELECTOR VALVE, FIRST MEANS INTERCONNECTING SAID SOURCE OF FUEL WITH SAID SELECTOR VALVE, A PRESET HIGH LIMIT THERMOSTATIC VALVE IN SAID FIRST MEANS TO PREVENT COMMUNICATION BETWEEN SAID SOURCE OF FUEL AND SAID SELECTOR VALVE ONLY WHEN THE TEMPERATURE EFFECT OF SAID BURNER MEANS EXCEEDS A BROILING TEMPERATURE EFFECT, SECOND MEANS INTERCONNECTING SAID SELECTOR VALVE WITH SAID BAKE BURNER MEANS SO THAT THE BAKING TEMPERATURE EFFECT OF SAID BAKE BURNER CAN BE THERMOSTATICALLY CONTROLLED INDEPENDENTLY OF THE OPERATION OF SAID HIGH LIMIT THERMOSTATIC VALVE, AND THIRD MEANS INTERCONNECTING SAID SELECTOR VALVE WITH SAID BROIL BURNER MEANS WHEREBY SAID SELECTOR VALVE CAN SELECTIVELY DIRECT FUEL TO EITHER SAID BAKE BURNER MEANS OR SAID BROIL BURNER MEANS ONLY WHEN SAID HIGH LIMIT THERMOSTATIC VALVE IS OPEN.

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