US1135700A

US1135700A - Gas-oven.

Info

Publication number: US1135700A
Application number: US81539014A
Authority: US
Inventors: August H Kohlmeyer
Original assignee: THERMO AUTOMATIC STOVE Co
Current assignee: THERMO AUTOMATIC STOVE Co
Priority date: 1914-01-30
Filing date: 1914-01-30
Publication date: 1915-04-13
Anticipated expiration: 1932-04-13

Description

A. H. KOHLMEYER.

GAS OVEN. APPLICATION FILED JAN- 30, 1914.

Patented Apr. '13, 1915.

3 SHEETS-SHBBT 2.

lmwil zizi A. H. KOHLMEYER.

GAS OVEN.

APPLICATION FILED JAN-30, 1914.

Patented Apr. 13, 1915.

3 SHEETSSHEET 3.

AUGUST H. KOI-ILMEYEB, OF ST. LOUIS, MISSOURI, ASSIGNOR TO THERMO AUTOMATIC STOVE COMPANY, OF ST. LOUIS MISSOURI, CORPORATION OF MISSOURI.

Specification of Iietters Patent. v Patented Apr 13, 1915.

Application filed January 30, 1914. Serial No. 815,890.

To all whom it may concern:

Be it known that I, Auoosr H. KOHL- MEYER, a citizen of the United States, and a resident of the city of St. Louis and State of Missouri, have invented a new and useful.

Improvement in Gas-Ovens, of which the following is a specification.

My invention relates to ovens, particularly to that type in which gas is used for supplying the necessary heat to the oven.

The principal object of my invention is to provide an oven heated by gas which will be economical in the use of gas, and which will require the least amount of attention by the user.

A further object of my inv'ention'is to provide a simple and efficient construction having certain other advantages as will appear more fully hereinafter.

The invention consists in a chamber capable of absorbing and -retainin amount of the heat necessary cooking, and mechanism associated with said chamber for facilitating the lighting of the gas burners used for heating the chamber, and for automatically cutting off the supply of gas to the burners when the necessary amount of heat has been supplied to said chamber. The invention further consists in the parts and the arrangements and combinations of parts, as will be set forth hereinafter.

In the accompanying drawings, which form part of this specification and in which like reference characters refer to like parts throughout the several views, Figure 1 is a' vertical cross-section of an oven embodying my invention, the section being taken on the line 11 of Fig. 2; Fig. 2 is a horizontal section on the line 2-2 of Fig. 1; Fig. 3 is a detail in horizontal section showing the ignition plug; Fig. 4 is a rear elevation with parts in section; Fig. 5 is a detail in end elevation with a part in section taken on the line 55 of Fig. 6, showing the gas and air inlet to a burner; Fig. 6 is a detail in horizontal section taken on the line 6-6 of Fig. showing the gas and air inlet toa burner;

Fig. 7 is a fragmentary top plan of the bottom plate of the heating chamber of the oven; Fig. 8 is a fragmentary bottom plan of the bottom plate of the heating chamber of the oven; Fig. 9 is a fragmentary vertical section taken on the line 99 of Fig. 7; Fig. 10 is an enlarged detail in vertical section in end elevation, showin a large or proper showing the cam wheel and its associated' showing the safety device of the ignition mechanism; Fig. 13 is a fragmentary detail thesame parts as are shown in Fig, 12; Fig. 14 is a detail in horizontal section, showing theasame parts as are shown in Fig. .12, ,the section being taken on the line 1 1-14 of Fig. 13;

In the form of construction which I have shown as embodying my invention, the oven as a whole is supported upon legs 1 and comprises anouter chamber 2 provided with

double walls

3 and 4. Between the walls 3 and. 4 is packed a material 5 having heat insulating qualities, preferably mineral wool. The front wall of the chamber'2 is provided with a door opening 6, the faces of the side edges of which incline from the inside outwardly. In the door opening ismounted, on any suitable form of hinges 7, a door 8, which is similar in construction to the walls of the chamber and is formed with double walls 9 and 10 packed with heat-insulated material 11.- The edge faces of thedoor 8 are inclined to fit tightly against the edge faces of the door opening 6. The door 8 is provided with any suitable form of catch 12.

Within the chamber2 is disposed the heating or cooking chamber 13 of the oven, which comprises a top plate 14, a bottom plate 15, andtwo side plates 16 and 17. The rear wall of the heating chamber 13 is formed by the rear inside wall of the chamber 2, and the front wall is formed by the rear wall of the door 8. The heating chamber 13 is heated by burners which are preferably 'arranged in pairs extending from the front to the back of the chamber 2. The burners are shown in this instance as being perforated tubes 18, each of which is secured to the front inside wall of the chamber 2 by a flanged socket 19 (Fig. 3). Each of the tubes 18 is secured at its rear end by an upstanding bracket 20.

Over the rear end of the burner tubes 18 are caps 21. with rounded rims. Each of the caps 21. is provided with apair of segmental openings 22, and fitted over the end face of each cap 21 is a cover 23 having segmental tion on ac'entral boss 25 on each cap 21 and 1 has its circumferential edges bent in to press pipe 26 is provided with a screw-threaded.

plug 29 opposite the end of each inlet pipe 27, and these plugs 29 may be removed to clean the inlet pipes 27. The main pipe 26 issupported by brackets '30 secured to the outside rear wall of the chamber 2. The segmental openings 22 and'24 in the cap 21 and cover 23 when registered serve to conduct air'to the burner tubes 18. The rear wall of the chamber 2 is provided with a rectangular opening 31 to permit the air to have access to the burner tubes 18.

The bottom plate 15 of the heating chamber 13 is supported upon angle'irons 32 extending from the rear inside wall of the chamber 2 to the front inside wall. The

. bottom plate 15 is provided with a number of perforations 33 arranged in transversely and longitudinally extending rows, the perby transverse. and

forations 33 being in staggered relation toone another. On the top face of the bottom plate 15' the perforations 33 are connected longitudinal grooves 34 V-shape in cross-sectlon and intersecting with one another. On the bottom face of the bottom plate 15 are similar grooves 35 which pass between the perforations 33. The grooves 35. on'the bottom face of thebottom plate 15 serve to increase the heatmg bottom plate 15 increase the heating surface and also permit the heated air passing through the perforations 33 to spread'out i into along the bottom ofany cooking vessel standing on the bottom plate. The side-plates 16 and 17 of the heating chamber 13 are supported upon the angle irons 32. Each of the' side-plates 16 and 17 isheldrin position by a pair of angle brackets 36riveted or otherwise secured to the rear inside wallof the chamber 2 and to the corresponding side-plate. The side-plates 16 and 17. are spaced from the inside side walls of the chamber 2 and are provided with a plurality of projections37 extending the spaces. Theseprojections 37 are preferably conical in shape and integral surface of the bottom plate. ,The perforations 33 through the bottom plate 15 serve to conduct heated air from the burnerplate 14 rests upon the top edges of the si e-plates 16 and 17 and is held in osition by rivets, or other suitable form of astening' means, passed through integral lugs 38 into the rear inside wall of the cham her 2.

' In the rear wall of the chamberis 9. rectangular vent opening 39 having its lower edge approximately level with the top face serves to carry ofi' the products 0 com ustion from the inside of the chamber 2 and prevents. the air within the chamber from becoming too impure for proper combustion of the gas.

Formed integral with the top plate on its top face are a number of spaced bafiie plates 40 extending angularly toward the front of the top plate 14. These baflle plates 40 extendto the top of the chamber 2 and serve to distribute the heated air passing up through the. side spaces evenly over'the top face of the top plate 14. In each of the side-plates 16 and 17 .at the top and bottom near the front edge are small holes 41. The top plate 14 is rovided with a number of projections 14' mtegral therewith and arranged in staggered relation to one another in transverse and longitudinal rows.

The bottom plate 15, side-plates 16 and 17, and top plate 14 are composed of some heat-absorbing material, preferably cast iron. Disposed within the heating chamber 13 are a number of slidable shelves 42 supported on angle irons 43 suitably fastened to the side-plates 16 and 17.

The main supply pipe 26 is provided with a valve 44 of the rotary type. The valve stem of the valve is connected to a shaft 45 which is supported in a bracket 46 at one end, and in a pair of spaced brackets47 at the other end. Encircling the shaft 45 is a coiled spring 48, the ends of which are secured to the shaft 45 and to the bracket 46 respectively. The spring 48 is wound so as to bend to turn the shaft 45 in the direction indicated by the arrow on Figs. 1 and 11, and to. turn the valve 44 to its closed position.

The vent opening 39 is provided with a sliding damper 49 fastened to one end of a sliding damper rod' 50, which is supported in gui es 51. The other end of the sliding damper rod 50 has fastened thereto a sliding damper 52 which is adapted to cover the inlet opening 31. This sliding damper v52 is provided'with slots 53 to pass over the of the top plate 14. This vent o own 39 I connected" a link 56.

inlet pipes 27, and secured to the outside wall of the chamber 2 below the inlet pipes are strips 54 which underlie the slots 53 when the damper 52 is in its closed position.

Secured to the end of the shaft 45, which is extended beyond the valve 44, is a crank arm 55, and to this crank arm is pivotally This link 56 extends across the back wall of the chamber 2 and is pivotally connected to the'ends of a link 57 and a link 58. The link 57 is pivotally connected at its other end to the damper 49. The link 58 is pivotally connected at its other end to the outside-wall of the chamber 2. The sliding damper rod 50 is provided with an angularly extended perforated lug 59, in the perforation of which is the bent end of a piston 10d 60. Attached to the piston rod 60 is a piston 61 which fitsinto an air-tight dash-pot cylinder 62. The dashpot cylinder 62 is provided at its lower end with an adjustable relief valve 63.

The damper 49 is provided with a small perforation 64. In the closed position of the damper 49 the perforation 64 may be coveredby an auxiliary damper plate 65.

mounted on the end of a slidable rod 66. The slidable rod 66 is mounted at one end in a guide 67 secured to the top of the chamber 2 and its other end passes through alined openings in the inner and outer Walls of thefront of the chamber.

A knob 68 fastened to the end of the rod 66 which extends through the front walls of the chamber 2 furnishes a convenient means for manipulating the rod.

A hood 69 is pl ced over the damper 49 and the vent opening 39 and is secured to the rear outside wall of the chamber 2 by rivets passing through marginal flanges of the hood. The hood 69 is formed with a slot 7 0 to accommodate the movement of the link 57 and the sliding damper rod 50. The walls ofthe hood 69converge at the top to form a pipe '71, which is adapted to have secured to it any desired length of pipe (not shown) leading to the outside air.

The spring 48 tends to turn theshaft 45 to a position to close the dampers 49 and 52 and the valve 44. A device is provided which holds the shaft 45 against the action of the spring 48 in the posit-ion'where the dampers 49 and 52 and the valve 44 are open, and which is operated to release the shaft 45 when the heating chamber has attained a certain predetermined temperature. Disposed within the spaces between the sideplates 16 and 17 and the inside walls of the chamber 2 near the front is a pair of

rods

72 and 73. These

rods

72 and 73 are com- 'posedof a material capable of expanding when heated and are preferably copper Between each side-plate 16 and 17 and the her 2'by a bolt 74*.

corresponding side Wall of the chamber 2 is fastened a bar 74 Z-shape in cross section, which is located near the front of the chamber 2, back of the

rods

72 and 73, and which is extended from the top to the bottom of the side-plate. These bars 74 serve to protect the

rods

72 and 73 from the direct act1on of the heat of the burner tubes 18, and make it certain that the parts of the heatmg chamber 13 will be evenly heated to the same temperature as the rods. I have found that it is desirable in' some instances to cover the rods 72 and73 with a thin layer of asbestos or some other poor conductor of heat in order to secure the same temperature of the rods and of the parts of the heating chamber 13.

One of the rods 72 is fastened at its upper end to the inside front wall of the chain? The lower end of this rod 72 is pivotally connected to the bifurcated end of a lever 75 by a pin 76. The lever 7 5 is pivoted on a bolt 77 secured to the inside front wall of the chamber 2 at a point located at a distance approximately one-fourth of the length of the lever from the bifurcated end thereof to which the lower end of the rod 72 is pivoted. The other end of the lever 75 is bifurcated and is pivoted by a pin'78to the lower end of the other rod 73. The upper end of this rod 73 I extends through a circular hole in the top of the chamber and is pivoted by a pin 79 to the bifurcated end of a bar 80. The bar 80 extends across the top of the chamber 2 on the outside near the front and one end projects beyond the side of the chamber. This projecting end is bifurcated and is pivoted by a pin 81 to the upper end of a rod 82. The rod 82 extends down the side of the chamber 2 on the outside near the front and is guided between its ends in a bracket 83.

Below the bracket 83 the rod is curved out wardly, then downwardly andvits lower end The end of this hook portion 84 is formed with an upward incline 85 and at the end of this incline is pivoted a roller 86.

Fixed to the shaft 45 between the brackets 47 is a sleeve 87 having a radially extending finger 88. 'Thefinger 88 is shaped at its end to forma laterally extending projection 89 curved on the arcof circle. The projection 89 is adapted to engage with the roller 86.

Pivotally mounted in a slot in the circumferential face of the sleeve 7 is a rolle 96 which is adapted to bear against the lower downwardly extending portion of the rod 82.

Fixed to the end of the shaft 45 by a pin 91 is an arm 92 provided with :1, vxmnlea handle 93. I

Fastened to the top of the chamber 2 on the outside at a point approximately onethird of the length of the bar 80from the ivoted, 95 is end thereof to which the rod 82 is is a U-shaped bracket 94. Asha mounted 'for rotation in the arms of the of the bracket 94 is a leaf spring 97 which presses against the side of the cam wheel 96 and by the friction of its. contact holds the cam wheel in its different positions. A

housing 98 is positioned over the bar 80, bracket 94 and cam wheel 96. The housing 98 is provided with a. slot 99 extending downwardly from the shaft 95 to the bottom so that the housing 98 may be removed to give access to the difl'erent parts. A dial 100 is secured to the bracket 94 and is dis posed on the outside of the housing 98. inned to the shaft '95 is a knob 101 carrying a pointer 102 which is arrangedto moveover the face of the dial 100. The dial 100 is preferably graduated in spaces to represent degrees of temperature. Bearing upwardlyagainst the barSO near the end to which the rod 82 is pivoted, is a leaf spring 103 fastened to the chamber 2. Above the bar 80 at this point is a tap bolt'104.which is screw-threaded into the housing 98 and bears against the top of the bar 80.

Forthe purpose of lighting'the gas burners with the least amount of difiiculty there is provided a mechanism for igniting the gas burners by an electric spark. Near the front, through one of the side walls of& the chamber 2, is a tube 105 which is flanged at H one end and fastened by screws to the outher 2 be open when the side wall of the chamber 2. The other end of the tube 105 extends within the chamber 2 to a point above and to one side of one of the burner tubes 18 and this point is preferably outside of the path of the flame When the adjacent burner tube is lighted. The bore of the tube 105 is filled with insulation 106 in which is embedded a rod 107. The rod 107 extends beyond the inner end of the tube 105 and is bent to bring its tip end adjacent to the end face of the tube. The

tube 105 and the rod 107 constitute a simple construction for forming and positioning an electric spark.

It is desirable that the door 8 of the chamgas is ignited so that there will not be any damage done in case there is some explosive force to the ignition. A rectangular plate 108 is fastened by screws to the outside front wall of the chamber EZ'near the edge of the door 8. An angle lever 109 is pivotally mounted on the plate 108 by a screw 110, and one end 111 of the I angle lever 109 engages a block 112 screwed to the outside face of the door 8 near its hinged edge.

Supportedbetween a lug 113 on the plate 108 and the end 111- of the angle lever 109 is an expanding coil spring 114 which serves to project the end of the angle lever when the door 8 is in open'position. The other end of the angle lever 109 is bent back to extend parallel with theside of, the chamber and terminates in a spring contact member 115. The arm 92 has a contact tongue 116.

member 115 is raised out of alinementwith the contact tongue 116. A suitable housing 118 .is placed over the angle lever 109 and spring 114. r

The circuits of the electrical igniting mechanism are shown diagrammatically in Fig. 2. Any suitable form of battery 119 and induction or spark coil .120 may be used. The circuit for the primary of the induction coil is as follows: positive of the battery 119, conductor 121, primary of the coil 120, conductor 122, contact member 117, contact.

tongue 116, contact member 115, to thebody of the chamber 2, and conductor 123 back to the negative of the battery 119. The circuit for the secondary of the induction coil is as follows: From one terminal of the secondary by conductor 124 to rod 107, air ap between the rod 107 and the tube 105 tu e 105, body of chamber 2, conductor 123, conductor 125, back to the otherterminal of the secondary.

In the operation of the device shown and described, the door 8 is first opened. The door 8 being in open position, the end 111 of the angle lever 109 is permitted to pro- I ject under the force of the spring 114, and

the contact member 115 is positioned opposite the contact member 117. The handle 93 is now turned to the left (accordin to Fig. 11). This movement, by rocking t e shaft '45, opens the valve 44 and the contact tongue 116 by engaging between the con-' tact member 115 and the contact member 117, completes the circuit through the primary of the induction coil 120. The secondary of the induction coil 120 causes a spark across the air gap between the rod 107 and the tube 105, and this spark ignites the gas.

incline 8 5 and pushes'down the horizontal lever 109 is forced back and the" contact During the movement of the handle 93 to the left, the arm 88 engages the 1,135,700 fijli.

portion 84 of the rod 82. After the gas is ignited, the handle 93 is released and the spring 48 rocks the shaft 45 to the position shown I in Figs. 2 and 14. In this position the roller 86 engages the rounded projection 89 of the arm 88 and holds the shaft 45 against return movement, the contact tongue 116 being out of engagement with the

contact members

115 and 117. In this position of the shaft 45 the valve 44 and the dampers 49 and 52 are in full open position. lVhen it is seen that the gas is lighted, the door 8 is closed. The cam wheel 96 is now adjusted by the knob 101 to place the pointer 102 opposite the mark on the dial 100 which corresponds to the temperature at which it is desired to shut off the supply of gas. The manipulation of the device is now ended and further operation is automatic.

As the heating chamber 13 becomes heated, the

rods

72 and 73 expand and lengthen. On account of the location of the pivot bolt I 77 of the lever'75, the distance which the rod 72 expands is multiplied approximately four times at the lower end of the rod 73. To

four times the distance which the rod 72 ex-' ands is added the distance which the rod 3 expands. The expansion of the rods 72 with the mm wheel 96 now becomes a fulcrum for the bar 80 and further upward movement at the end of the bar 80 to which the rod 73 is. attached causes a downward movement of the rod 82. This downward movement of the'rod 82 releases the arm 88, permits the spring 48 to rock the shaft 45, carrying with it the crank arm 55. movement of the crank arm 55 by means of the

links

56, 57 and 58 pulls the sliding damper rod 50 downward to close the dampers 49 and 52. The dash-pot cylinder 62 prevents too rapid and sudden a movement of the sliding damper rod 50. The tap belt 104 is adjusted so that the upper position of the rod 82 places the axis of the roller 86 nearer the center of the shaft 45 than the point of contact of the roller 86 and the rounded end of the projection 89 of the arm 88. The parts may be adjusted so that the shaft 45 will be held against movement in the direction of the arrow on Figs. 1 and 11, and yet will be released by a very small movement of the rod 82.

The air supplied to the burner tubes 18 is regulated by turning the covers 23, and the gas may be regulated by substituting for the plugs 28 other plugs having different sized bores. The holes 41 in the side-plates 16 and 17 allow steam and vapor in the heating chamber 13 to pass out into the chamber 2. When the damper 49 is opened, this steam or vapor may pass with the heated air out through the vent opening 39. When the The and vapor in the heating chamber 13 may be permitted to escape while the heating chamher is closed.

An oven constructed according to my invention will use much less gas than an oven of the ordinary type. In the ordinary oven, a large proportion of the heat passes through the side walls into the surrounding room. This makes the temperature in the room uncomfortably high and also Wastes heat.

It can be determined accurately what temperature of the heating chamber is necessary to properly cook different kinds of food, and when the pointer is set to that temperature on the dial, no further attention is necessary. Also, it is certain that the food will not be overcooked or spoiled by being burned. It has been found by actual tests that a single meal may be cooked in an oven of the type shown and described with only one-half of the gas needed to cook the same meal in an oven of the ordinary type. In these tests, a

cold oven was used, and ifv it can be arranged to take advantage of an oven partly heated from a preceding cooking operation, much greater economy can be effected.

Obviously, the oven which I have shown and described as an embodiment of my invention may be considerably modified without departing from the spirit of my invention. Therefore, I do not wish to be limited to the particular construction illustrated and described.

What I claim is:

1. In an oven, a chamber having double walls filled with a heat insulating material, a cooking chamber in said chamber having metal Walls spaced from the inner walls of said chamber, said first mentioned chamber completely surrounding said cooking chamber, a burner below said cooking chamber and heating the bottom, top and side walls thereof, a valve for controlling the supply of heating medium to said burner, a vent opening in said first mentioned chamber, a damper for closing said vent opening, a member mounted in said chamber and capable of expanding when heated, means controlled by said member for closing said valve and said damper, and means for varying the amount of movement of said member necessary to set said last mentioned means into operation.

2. In an oven, a chamber having double walls filled with a heat insulating material, a cooking chamber withinsaid chamber and having metal top, bottom and two side walls spaced from the inner walls of said chamber, said side walls and said top of said cooking arranged in staggered relation, said pins extending out into the space between thetop and two side walls of said cooking chamber and the inner walls of said first mentioned chamber, a vent opening in said first menthereof and above the top of said cooking chamber, and a plurality of baflleplates on the upper surface ofthe top of said cooking chamber, said bafile plates extending at an angle to said walls of said cooking chamber.

3. In an oven, a chamber, a burner within said chamber, acooln'ngchamberjvitliinsaid top -face,"o

transverse and longitudmal grooves-interchamber having its top, bottom two side walls spaced iromthe inner walls-of 15 said chamber, said bottom being disposed above'said burnerand comprising a metal plate having a series of holes therein arranged in transverse and longitudinal rows and in stag cred relation to one an'other,.the

' said. plate being formed with secting .said holes, and the bottom face of said plate being formed with transverse and longitudinal grooves lying between sald 2 ho1es and intersecting one. another.

4. In an oven, a chamber, a cooking chamberwithin-said chamber and having its top, 1 bottom and two side walls spaced from the inner walls of said chamber, said top, and

tween the inner walls of said chamber and 5 tioned chamber located in the rear wall 3!) side walls being ofamaterial capable of absorbing heat and having on their faces aplurality of integral pins arranged in staggered relation and extending out into the space besaid top, and two side walls, the under facefor supplying air to of the bottom of said cooking chamber hav ing a number of intersecting grooves therein.

5. In an oven, a chamber having walls of a material capable of absorbing heat, heat -40 insulated walls completely surrounding said chamber, there being a space between the top, bottom and walls of said cooking chamber and said heat insulated walls, a gas burner for heating said chamber, an opening said' burner, a vent openmg, dampers for closin said opening and said vent opening, a va ve controlling the supply of gas to said burner, means for closing said valve and for "shutting said .velv for 'cpntr l g t rounding said (member,

valve o en, said'means being opersted by;

va ve,an means" said member to release said for varying the amount of movement of said member necessary to set said last mentioned means into operation.

7. an oven, a cookingchamber," heat in-- sulated .walls surrounding said chamber, a burner for supplying heat'to said chamber, a

mediumto ;said burner-,a aft operatively connected to. valve, 8. spring connected sulpply of heating to said shaft and ten g to turn said shaft in the direction to close said valve, avent opening the heat insulated walls sura damper for closing ud -Y. open ng shaft,"a,t ripme'c anism for holding said shaft in the pqsiti (n in which said valve and and connected to said said damper'are open, and means controlled i by the tem erature in said chamber torlre leasing said tri mechanism, said means being adjustable cm the outsideof'said heat insulated walls,-whereby the temperature at which said.- Yalve'and said dampers will be closed can bevaried."

8. In an oven, :1 cooking chamber, heat insulated' walls1 surrounding said chamber, a

burner for supplying heat to said chamber, a valve forgcontrolling the supply of. heating medium to said burner, a vent opening in the ,heat'-;.insu'lated walls surroundin said chamber, a damper for closing sai vent opening, means. tending to close said damper, and a dash-pot for retarding the closing movement of said damper, the closing movement of said damper being controlled by the closing movement of said valve.

9. In-- an oven, a cooking chamber having walls of a material capable of absorbing -rounding said chamber,

' f .50, dampers, said means be controlled by temperature in said cham er, said mean's'being adjustable "whereby the amount ofheat supplied to said cooking chamber necessary to set said means into operation can be .515; varied.

a 6. In an oven, :1. cooking chamber,said cooking chamber being completely surrounded by a second chamberhaving heat insulated walls, a gas burner within said #0.. second chamber for heating said cooking chamber, a valve for controllin of gas to said burner, a spring or normally closing said valve, a member mounted in said secgxlid chamber and cafpableof expandthe supply heated, means or holding said heat, heat insulated walls completely surthere being a space between said cooking chamber and said .heat

insulated walls, a-"gas burner for supplying heat to said chamber, avalve for controlling the supply of gas to said burner, a vent opening .in said chamber, a damper for closing said vent opening, and means for damper,-said means being controlled by the temperature in said chamber, said means shutting said valve and for closing said being..adjustable from the outside of said heat insulated walls, whereby the amount of heat supplied tos'aid'cooln'ng chamber which .is necessary to set said means into ope'ration a heat insulated chamber,

the supplyof gas to said burner.

tric device 'forlighting said. burner which.

a gas burner for supplying heat to said chamber, mechanism for automatically cutting off the supply of gas to said burner after a predetermined amount of heat has been supplied to "said chamber, means for lighting said burner which is set into operation when said mechanism is placed in operative position, and a door in said chamber, said means for lighting said burner being incapable of being operated when said door is closed.

12. In an oven, a heat insulating chamber, a gas burner for supplying heat to said chamber, a valve for controlling the supply of gas to said burner, a rotatable shaftconnected to said valve for opening and closing it, a bar, members in said chamber capable of expanding when heated and connee to said bar at one end thereof, a spring connected with said shaft and tending to move said shaft in a direction to close said valve, trip mechanism for holding said shaft in the position in which said valve is open, means operatively connecting said trip mechanism and the other endof said bar, and adjustable means for engaging said'bar intermediate the ends thereof and forming a fulcrum for said bar.

13. In an oven, a chamber, a gas burner for supplying heat to said chamber, a valve for controlling the supply of gas to said blu'ner,

a shaft operatively connected to said valve,

a spring connected to said shaft and tend- I ing to turn said shaft in a direction to close said valve, an arm on said shaft having a rounded end and having a roller rotatably mounted in its side face, a rod having a hook end, the point of said hook end having a roller rotatably mounted therein, said hook end in its operative positionengaging said arm, the roller on the point of said hook engaging said rounded end of said arm with the axis of the roller nearer the center of the shaft than the line of contact between said roller and said rounded end, and means for moving said hook out of engagement of said arm to release said shaft.

14. In an oven, a chamber, a door in said chamber, a burner for heating said chamber, a valve for controlling the supply of heating medium to said burner, a spring for closing said valve, means for holding said valve open, a hand lever for setting said means in operative position, and ignition means set into operation by moving said hand lever to said operative position, said ignition means being inoperative when said door is closed.

15. In an oven, a heat insulated chamber,

"a burner for heatingsaid chamber, a valve forcontrolling the supply of heating medium tosaid burner, a vent opening for said chamber, an'air opening for supplying airto said burner, dampers for said vent opening and for said air opening, a spring for automatically closing said damper and shutting said valve simultaneously, and a dash pot for retarding the movement of said damper.

16. In an oven, a burner for supplying heat to said oven, a valve for controlling the supply of heating medium to said burner, a spring for closing said valve, trip mechanism holding said valve in its open position, members within said chamber capable of expanding when heated, a bar connected at one end to. said members and at the other end to said trip mechanism, a cam wheel rotatably mounted on said chamber at a point intermediate the ends of said bar and adapted to be engaged by said bar to form a fulcrum therefor, a fixed dial, and a pointer secured to said cam wheel and movable over the face of said dial.

17. In an oven, a heat insulated chamber, means for heating said chamber, a vent opening for said chamber, a damper for closing said vent opening and having a small perforation therein, an auxiliary damper for opening and closing said per-' foration when said damper is in closed position, means for automatically closing said damper when said chamber has attained a predetermined temperature, said means operating without interfering with said auxiliary damper, and a rod extending through a wall of said chamber and connected to said auxiliary damper.

18. In an oven, a chamber, a gas burner for heating said chamber, an electrical igniting device for lighting said burner, a circuit for said electrical igniting device, a valve for controlling the supply of gas to said burner, a hand lever connected to said valve and having a contact tongue for closing said circuit, a spring operatively connected to said hand lever and tending to close said valve, and releasable means for holding said hand lever in the position where said valve is open and said circuit is broken.

19. In an oven, a chamber, a gas burner for heating said chamber, a valve for controlling the supply of gas to said burner, a spring connected to said valve and tending to close it, a trip device. for holding said valve open, a member in said chamber capable of expanding when heated, means operatively connecting said member and said trip device, and a means for varying the amount of movement of said member necessary to set