US2950865A

US2950865A - Thermostatic control apparatus for a burner

Info

Publication number: US2950865A
Application number: US605064A
Authority: US
Inventors: Charles C Lamar
Original assignee: Harper Wyman Co
Current assignee: Harper Wyman Co
Priority date: 1956-08-20
Filing date: 1956-08-20
Publication date: 1960-08-30
Anticipated expiration: 1977-08-30

Description

United tatc s Charles C. Lamar, Chicago, Ill., assignor to Harper- I atent Wyman Company, Chicago, 111., a corporation of lllinols Filed Aug. 20, 1956, Ser. No. 605,064

5 Claims. (Cl. 236-32) The present invention relates to thermostatic control apparatus and has for its primary object the provision of a new and improved thermostatic control for burners, such, for example, as the burners of a gas range.

It has been proposed from time to time to provide gas ranges with thermostatic controls and in the past such controls have been provided primarily for the oven burners. More recently, it has become desirable to provide also thermostatic controls for the top burners of gas ranges and the present invention has to do primarily with controls for the top burners, although certain features of the invention are applicable equally well to oven burners. Furthermore, the present invention has for an object the provision of a thermostatic control for what is generally known as a double burner. A double burner, for the purposes of the present invention, may be considered to be a burner having a first and larger burner, generally termed the main burner or main burner section, and a smaller burner, generally called a simmer burner or simmer burner section, and which is generally located in close. proximity to the main burner.

The control of the present invention is so constructed and arranged that in one range of operation gas is supplied only to the smaller or simmer burner and in quantities thermostatically modulated or regulated in accordance with the heating requirements of the space or device to be heated, such as a cooking vessel, and which, for purposes of simplicity, Will hereinafter be called a device. In a second range of operation, as when the heating requirements are greater, then gas is supplied to both burners and the flow of gas is again regulated and modulated as by controlling the rate of flow to the larger burner.

It is, accordingly, a further object of the present invention to provide a new and improved thermostatic control for a double burner which is constructed and arranged to provide what might be called a sequential control of the flow of gas to the different burner sections, as, for example, a control of flow to the smaller burner section only in one range and the control of flow to at least the larger of the two sections in another range of heating requirements.

A further object of the present invention is the provision of a control of the character set forth above in which a single manually operable means is Provided to control the flow of gas to both burner outlets and also to adjust the temperature-responsive means to maintain a preselected temperature of the device to be heated.

A still further object of the present invention is the provision of a new and improved thermostatic control for a double burner including thermostatic means for controlling the rate of flow to the burner sections such that only one section is supplied with fuel in a first range of heating requirements and both sections are supplied with fuel in a second range of heating requirements and in which, furthermore, there is provided a definite dwell in which gas is supplied only to the smaller burner over an intermediate range of requirements be tween the supplyof fuel to the smaller burner only and the supply of fuel to both. This intermediate range constitutes a definite boiling rate position which can be correlated with manually adjustable thermostat adjusting means to provide a definite, assured input, which may be that of the full rate of the'smaller burner section, over a predetermined angular range of adjustment of the manual temperature adjusting means.

The aforesaid construction thus provides a control adapted to maintain a definite boiling condition, for example in a utensil heated by the burner for at least the usual variations in vessel size, vessel material and atmospheric pressure. With thermostatic controls now available, there is danger of too great an input, rapid evaporation, and burned food on the one hand, or a drop in rate after the usual overshoot in either the increasing or decreasing direction of control, with the result that boiling is not maintained. In the apparatus of the present invention, there is provided a broad and definite, reproducible boiling rate setting which assures an easily set boiling position in which boiling is assured with a definite boilaway rate. For temperatures of boiling and below, there is no on-off cycling of the main burn-' er, no danger of flashback or escaped unburned gas nor odors from fluttering and traveling flames.

A further object of the present invention is to pro,- vide new and improved double acting thermostatic control valves for regulating the flow of fuel to double burners which may be constructed relatively simplyand economically.

A still further object of the present invention is to provide a new and improved double acting thermostatically actuated control means in which the thermostatically controlled valves are coaxially located relative to each other and to the thermostatic control means and manually operable valve and thermostat adjusting means.

In brief, one embodiment of the apparatus of the present invention includes a manually operable valve and a pair of thermostatically controlled valves located coaxially relative to the manually operable valve and adapted sequentially to be opened and closed to supply regulatable quantities of gas to outlets leading to the main and simmer burners of a double burner. range of operation, both thermostatically actuated valves are open and the flow to the main burner alone is thermostatically regulated in response to the temperature of a device, such as a cooking vessel. In another range of operation the main burner valve is closed and the simmer burner valve is thermostatically regulated to supply gas to the simmer burner outlet passageway alone. As a changeover is made from regulation of the flow of gas to the main burner'outlet passageway to regulation of the flow of gas to the simmer burner outlet passageway, there is what may be termed an intermediate range of operation in which a full supply of gas is supplied to the simmer burner outlet passageway over an easily set broad position setting to provide a definite reproducible boiling rate setting with a definite boilaway rate. The two thermostatically controlled valves are so constructed and arranged that they can be readily mounted in the valve body and' so that they may readily be operatively connected to both the manually operable valve member and the thermostatically actuated control means.

Other objects and advantages of the present invention will become apparent from the following description of illustrative embodiments of the invention, in the course of which reference is had to the accompanying drawing,

inwhich:

The figure is a partly diagrammatic and cross-sectional view illustrating a double-acting thermostatic control valve for controlling the flow of gas to a double burner which has been illustrated but diagrammatically. I

In one Referring now to the drawing, it may be noted that the apparatus as a whole, which may be considered to be a thermostatically controlled system, is indicated by reference character it This system includes a multiplesection burner 12, illustrated only diagrammatically, and a double acting thermostatic valve, indicated by the reference character 14. V

The illustrated multiple-section burner is of the type which may be used in the top section of a domestic gas range and which is commonly called a double burner. It includes an annular main burner 16 and a second and smaller burner 18, which is illustrated as being located near the outer part of the main burner section, but which may be located elsewhere as desired. These two burner sections are adapted toheat a cooking vessel which has been illustrated but diagrammatically and which is indicated by the reference character 20. For the purpose of'the present invention, it should be noted, however, that this burner could be used to heat some space, such as an oven, instead of the vessel, and in order generically to cover both a vessel and space the word device is used herein generically to cover both.

The temperature of the cooking vessel and its contents is sensed by a temperature-responsive means 22 which has been illustrated but diagrammatically. It may be of known type and include an upwardly biased capsule containing a thermostatic fluid which is adapted to change its volume in response to the temperature to which it is subjected.

The control valve is connected to the burners and to the sensing element. The connection to the main burner 16 is through a conduit 24 which may include as a part of it the usual venturi or mixer tube and which is connected to a first outlet passageway 25 formed in a boss 30 in the control valve body which is indicated as a whole by reference character 32 and which is constructed in conventional manner either as a casting or forging. The simmer burner section 18 is similarly connected through a conduit 26 to a simmer burner outlet passageway 34 formed in the externally threaded boss 36. a

The connection of the control valve to the sensing element 22. is eifected through a conventional capillary tube 38 terminating at a thermostatic actuating element 40 taking the form of an expansible diaphragm comprising the separable elements 42 and 44. The tube 38 is coupled to the diaphragm by a coupling element 46 threaded into a removable cover plate 48 and locked in place by lock nut i Plate 43 is removably secured in place by a plurality of screws 52. The diaphragm actuates a thrust element 54 secured to the lowermost diaphragm element 44 and having a generally conical shape terminating in a rounded point 55.

The control valve includes a pair of thermostatically actuated

valves

90 and 96 controlling the flow of gas to the main and simmer burners and which will be described in greater detail hereinafter. The control or regulation of gas flow is such as to maintain the temperature of the contents of the cooking vessel at a predetermined value. When the cooking vessel is first placed on the burner and the burner turned on to maintain some predetermined temperature setting, as will be described hereinafter, gas is supplied at a full rate to both the burners. As the temperature of the vessel increases, the thermostatic fluid in the sensing element 22 expands so a portion of it is displaced into the diaphragm assembly and effects separation of the separable elements 42 and 44 to efiect regulation of the gas flow. In the embodiment of the valve disclosed, this regulation includes first the control of the flow of gas to the main burner, which is decreased as the temperature of the vessel increases. After the temperature has reached a certain value, the

, flow to the main burner is out 01f entirely, while the flow continues to the simmer burner section. As the temperature of the vessel continues to increase, the flow of lgas to the simmer burner section is gradually decreased to a low minimum flow. In accordance with a further feature of construction, the flow of gas to the simmer burner is never fully cut off until the valve is turned to an off position. Also, and this is an important feature of the valve, there is an intermediate range between the operation of the two burners and the operation of burner 18 only in which movements of the thermostatic actuating element do not affect the flow to the simmer burner, thereby to provide, as already indicated, a boil position which exists throughout a broad and definite dwell period.

The valve 14 of the present invention includes also a manually actuable on-ofi and temperature selecting valve element, such as the rotatable valve plug 60. The valve plug 60 is utilized not only to control the supply of gas from an inlet passageway indicated by reference character 62, but also to determine the temperature to be maintained within the cooking vessel or device.

The plug 60-is the Well-known tapered type and is mounted within a tapered plug-receiving chamber 64 formed in a tapered forward housing portion 66 which is coaxially located relative to the diaphragm 40 and the diaphragm actuated thrust element 54. This in-line construction also forms one of the features of the present invention.

The plug is adapted to be rotated by a manually actuable handle 68 secured to a valve stem 70 projectingforward of the plug. The handle is provided with an indicia 72 and associated with the valve is a dial 74 provided with suitable temperature indicia (not shown). The indicia 72 may be angularly movable relative to the handle for calibration purposes.

The plug is maintained in seated position within its chamber by a spring 76, one end of which bears against the plug and the other against a washer 78 which may form part of a position-indicating and determining mechanism of known type. The plug, washer and spring are maintained in assembled position by an end plate 80 secured to the front or lower end of the valve by the screws 82. If desired, the stem and handle construction may be of the locking type requiring inward movement of the handle in order to permit rotation of the valve plug.

The valve plug 61) is provided with an axial gas flow passageway 84 opening at the small end 86 of the valve plug. The plug is also provided with an arcuate slot 88 adapted to register with the inlet passageway 62 in the various operative positions of the valve plug. In the indicated position the slot 88 is shown in an elf position of the valve plug in which the inlet passageway 62 is closed by the plug. The valves 90 and $6 are also closed at this time. To open the valve plug, the handle 68 is turned in a counterclockwise direction, as viewed from the bottom of the figure and to an extent corresponding to the desired temperature to be maintained within the cooking vessel.

The valve 14 of the present invention, as already indicated, modulates or regulates the flow of gas to both the main and simmer burners. The flow to the main burner 16 is regulated by the first valve already referred to and indicated as a whole by the reference character 90 and including an annular valve seat 92 and a disc type valve element 94 movable relative thereto. The flow of gas to the simmer burner is regulated by the second valve 96 already referred to and indicated as a whole by reference character 96 and including an annular valve seat-98 and a movable sleeve type valve element 1%. Both valves 9% and 96 are shown in their closed positions, but under certain conditions they are adapted to be opened and closed under the control of the thermostat and, particularly, as a result of the movement of the thrust element 54.

The

valves

90 and 96 controlling the flow of gas to the two burners are constructed and arranged so that V r v the valve may be manufactured and assembled readily and inexpensively. Two subassemblies are utilized in the construction. One of these is primarily an ambient temperature compensating and over-travel accommodating structure indicated by the reference character 102 and the second is primarily a dual valve structure indicated by the reference character 104. These two sub-assemblies are mounted in line, i.e., coaxially, with the thrust element 54 of the thermostatic actuating means and the axis of the valve plug 60. The sub-assembly 102 is the upper one of the two and is mounted within a recess or chamber 105 in the valve body, in which the thermostatically actuated element 40 is also located, and which is closed by plate 48. The recess 105 is conveniently formed by a circular housing portion 106 disposed in line with the valve housing portion 66. Sub-assembly 102, it should be noted, includes the movable valve element 94 which is formed as the bottom of a cup-like element having annular side walls 107 and an outwardly extending annular flange 108 around which is located a clamping ring 110 having an internal rim portion 112 projecting inwardly beyond the wall 107. The sub-assembly 102 includes also a bimetallic ambient temperature compensating element or disc 114 having a central recessed or indented portion 116 for engagement by the rounded apex or point 55 of the thrust element 54 and having its outer periphery disposed underneath the inner portion 112 of the clamping ring 110. The bimetallic disc 114 is biased upwardly by a generally conical helical spring 117, the upper smaller diameter portion of which bears against the disc and the lower larger diameter portion of which is seated in the bottom of the cup-like element 94-407. In the off position of the valve 14, as indicated, the bimetallic disc 114 does not engage the inner edge 112 of the clamping ring 110 and valve disc 94 is seated on valve seat 92.

The sub-assembly 104 includes a tubular main valve seat member 120 having an upper flanged end 121 on which is provided the previously referred to valve seat 92, a sleeve 122 afiixed to member 120 and at the lower end of which is provided the previously referred to movable valve member 100, a shell 124 within which the sleeve 122 is slidably mounted and in which is formed the previously referred to valve seat structure 98, and a washer element 126 located above the sleeve 122 and shell 124 and below the upper flanged end portion 121 of the valve member 120. The sleeve and shell elements are biased for axial movement relative to each other in a direction tending to open valve 96 by a spring 128 and the two sub-assemblies are biased for movement away from each other in a direction tending to open the valve 90 by a spring 130. The

springs

117, 128 and 130 are of different strengths, the spring 117 being the heaviest, the spring 128 the lightest and spring 130 of intermediate strength, as will be brought out hereinafter.

The shell 124 has a generally tubular upper portion 134 which is externally threaded and mounted in an internally threaded chamber 136 coaxial relative to and located below chamber 105. It is provided with a radially inwardly extending portion 137, the inner part of which has a flat upper surface defining the valve seat 98 cooperating with the annular movable valve portion 100 of sleeve 122. It also has an axial central opening 140 for the flow of gas. The portion 137 is also provided with a pair of opposed, generally triangular slots 142 for the reception of the upper end of a flat stamping 144 forming an operative connection between the rotatable valve plug 60 and the sub-assembly 104 whereby the latter is adapted to be turned and axially moved by virtue of the threaded connection between the shell and valve. The connecting element 144 is a flat stamping and has a pair of wing-like portions 146 slidably engaged in parallel and diametrically opposed slots 148 formed at opposite sides of the axial passageway 84 in the rotatable valve plug 60, Element 144 is maintained in cooperative r v 6 relationship with the shell 124 by a spring 150, one end of which bears against the element 144and 'the other against the closed end of the valve plug 60.

As indicated heretofore, the valve 96, comprising the valve seat 98 and the movable valve member 100, controls the flow of gas to the simmer burner section. When the valve plug 60 is in an operative on position, the gas flows from the inlet 62 to the simmer burner section outlet passageway through the following path: inlet 62, slot 88 in the valve plug, axial passageway 84, chamber 136, axial opening in the shell, the now open valve portions 98 and 100, radial openings 152 in the shell, an annular slot 154 in the shell, and the radial passageway 156 communicating with the passageway 34 constituting the simmer burner outlet pasageway of the valve body.

The sleeve 122 is generally tubular in construction. It has a uniform diameter central opening 160 and an enlarged grooved outer portion 162 mounted in gas-tight sliding relationship in the shell 124. The sleeve 122 has also a small radial port 163 which, in the open position of the valve plug 60 and in the closed position of valve 96, provides a minimum flow of gas to the simmer burner section to maintain ignition at that section by providing a low and predetermined minimum gas flow. This minimum flow can be provided otherwise, as for example through a passageway connecting chamber 136 with passageway 156 and including adjustable means for determining the minimum flow. The upper ends of the shell and sleeve are designed to have their end faces in the same plane and a light grind in assembly assures perfect coplanar relation perpendicular to the axis of the valve plug and the valve assemblies.

The main valve seat member 120 is provided with a dependent tubular portion 166 press-fitted or otherwise secured as by cementing, in gas tight relation to the upper portion of the sleeve 122. The seat member includes the previously referred to annular outwardly extending portion 121, the underside of which is spaced above the sleeve and shell to provide an annular channel for the washer 126, the channel being indicated by reference character 170.

The washer 126 has a central opening through which the main valve seat 120 projects. It is centered on the shell by the sheared downwardly extending lugs 172 which engage the upper end of the shell; It has a peripheral upwardly extending flange 174 for retaining the lower end of spring 130.

The washer 126 has an accurately made step, as by coining, and indicated by the reference character to permit the sleeve 122 to move a slight distance as from about .001 to .004 inch away from seated relation with the shell, i.e., to permit the valve 96 to be opened about the specified distance before valve 90 starts to open. This amount of movement of the sleeve 122 is possible until the upper end of the sleeve 122 abuts against the washer 126, whereupon further opening movement of the simmer burner section valve 96 is prevented by the spring 130 which is stronger than spring 128.

From the foregoing detailed description of the invention, it can be observed that the valve can be readily constructed and assembled. The shut-off and temperature-selecting valve, including the valve plug 60, can be readily constructed and assembled in much the same way as an ordinary valve plug. The temperature-regulating portion can be assembled as sub-assemblies, one including the sub-assembly 104 which can be assembled and then inserted into the chamber 136. The sub-assembly 102 can similarly be assembled and inserted into' the chamber 105. The thermostatic actuating means 40 can be assembled and connected to the sensing element and mounted at the upper end of the valve body in a relatively simple manner. The construction thus pro vides a readily assembled and in-line type of construction 7 having a minimum of friction and eliminating all operating levers and the like.

The valve is illustrated in its closed position. In it the valve plug 60 shuts ott the flow of gasto both'burner sections by closing the inlet 62. At this time the valve 96 controlling flow to the simmer burner section and -the valve 90 controlling flow to the main burner secin a counterclockwise direction as observed from the underside of the figure. Such rotation of the valve plug 60 turns the interconnecting element 144- and the latter in turn rotates the shell 124, whereby the latter is moved downwardly. Initial downward movement of the shell 124 and the cup-shaped member 102 results in relative movement between them and the bimetallic disc 114 to the extent determined by engagement of the disc with the internally projecting portion 112. After the bimetallic disc and portion 112 engage, the cartridge assembly operates as a solid unit, save for the compensation for ambient temperatures occasioned by flexure of the disc in response to temperature changes in the vicinity of the valve.

Further rotary movement of the valve plug, which is accompanied by further downward movement of the shell 124 permits the weakest spring 128 to move sleeve 122 upwardly relative to the shell, thereby to open valve 96. This opening movement of the valve takes place until the upper end of sleeve 122 abuts against the coined step 180 of the washer 126. There is thus provided a relatively wide range or dwell in which there is a maximum or full flow of gas to the simmer burner section. Ordinarily, the dial is turned at least to this region in order to ignite the gas at the simmer burner section, which ignition may be provided as by a small, continuously burning pilot adjacent to the simmer burner section or by ignition means including a remote pilot connected to the simmer burner as by a flash tube. Prior to this time the simmer burner is supplied with a small amount of gas through the minimum flow providing passageway 163.

Continued rotation of the valve plug toward a higher temperature setting results in further downward movement of the shell 124 until the valve 90 is opened to supply gas to the main burner section- During this operation, spring 130 maintains cup 102 against the thrust element 54. burner sections supplied with gas and ignited, the temperature of the cooking vessel and contents gradually rises. As the temperature does rise, the temperature of the sensing element also rises and the expanding thermostatic fluid causes separation of the'diaphragm por tions 42 and 44. This results in downward movement of the thrust element 54 which acts through the relatively strongest spring 117 gradually to close the valve 90 by moving the disc element 94 toward the valve seat 92. If the temperature setting is relatively high, the only regulation may be that of regulating flow through thevalve 90 while a full flow is maintained through the valve 96 to the simmer burner section.

However, if a lower temperature is selected which does not require the continued operation of the main burner, then the main valve 90 closes and the thrust element forces the main valve seat element 120'and the sleeve 122 downwardly, thereby gradually to close the valve 96 to provide regulation of flow to the simmer burner section only. Thereafter, the flow to the simmer burner section may be regulated or cut oif by closure of the valve 96 so that the only flow that takes place is the:

With both valves open and both minimum flow through the port 163. In the event the temperature falls and the sensing element moves in the opposite direction,- the valve 96 is again opened and if the temperature is such that gas flow to the main burner section is required, the main valve is again opened.

One of the features of the present invention is provided by the construction requiring relative movement between the shell 124 and sleeve 122 to eitect closure of the valve 96. As indicated above, this relative movement may be, for example, between the .001 and .004 inch axial movement provided by the coined step and the inner portion of the washer 126. There is thus provided a substantial dwell which, expressed in angular movement of the valve plug 60, may be in the neighborhood of 40 degrees. As a result, there is provided what may be considered a boiling position in which a predetermined (full simmer) flow of gas is supplied to the simmer burner section in a range providing for boiling with a substantial variation in vessel size, vessel material and atmospheric pressure.

if desired, the minimum flow to the simmer burner section occurring in the closed position of valve 96 may be accomplished by means other than port 163 in the sleeve. For example, a separate bypass passageway in the valve body may be provided between chamber 136 and passageway 156. If this is done, a needle valve or the like may be provided therein for regulating or adjusting the minimum flow.

While the present invention has been described in connection with the details of an illustrative embodiment, it should be understood that these details are not intended to be limitative of the invention, except insofar as set forth in the accompanying claims.

Having thus described my invention, what is desired to be secured by Letters Patent of the United States is as follows:

1. Apparatus for controlling the passage of fiuid from one passageway to first and second other passageways, including in combination, concentric and axially spaced operatively connected first and second valves controlling flow from said one to said first and second other passageways respectively, and adjustable temperature responsive means for controlling said valves in response to temperature variations, one of said first and second valves including a structural unit comprising a cuplike housing the bottom of which constitutes a movable disc valve element, an ambient temperature compensating disc in said housing, spring means urging said elements away from each other and an inwardly extending flange structure on said housing engaging said compensating disc to limit its movement, and said valves including a structural unit comprising a pair of telescopically arranged tubular members each having an annular valve member, spring means biasing said members apart, and means providing limited axial relative movement between said members.

2. A valve including in combination, a valve body, a rotatable plug type shutoff valve element in said body for controlling the flow of gas therethrough from a gas inlet, said body having first and second outlet passageways, a composite dual valve structure mounted in said valve body in coaxial spaced relation to the inner end of the valve plug, said composite valve structure including a first tubular member having anannular valve seat at its end adjacent the plug valve and facing away from said plug valve and forming part of a first valve of said dual valve structure, said member being mounted for rotary and axial movement upon rotation of the valve plug, asecond tubular valve element movably mounted in telescopic relation in said first tubular element and having a tubular portion cooperating with said. annular valve seat for controlling the flow of gas from said plug valve to said first outlet passageway, said second tubular valve element having a radial passageway providing a predetermined minimum quantity of gas to said first outlet passageway, said second tubular valve element having a portion extending axially beyond the first tubular element and defining an annular valve seat forming part of a second valve of said dual valve structure and controlling the flow of gas to the second outlet passageway, means mounting said tubular members for limited axial movement relative to each other for providing a dwell range in which the second valve is closed and the first is open while a predetermined amount of said axial movement occurs, spring means biasing said tubular members for said relative movement, said second valve including a cup-like housing the bottom of which constitutes a movable disc valve engageable with said second tubular valve seat, spring means biasing said housing and disc valve away from said second annular valve seat, an ambient temperature compensating disc in said cup-like housing and movable relative thereto, spring means between said disc valve portion and said disc, means on said housing limiting movement of said disc relative to said housing, and thermostatically operated means engageable with said disc.

3. A valve including in combination, a valve body, a rotatable plug type shut-ofi valve element in said. body for controlling the flow of gas therethrough from a gas inlet, said body having first and second outlet passageways, a composite dual valve structure mounted in said valve body in coaxial spaced relation to the inner end of the valve plug, said composite valve structure including a first tubular member having an annular valve seat at its end adjacent the plug valve and facing away from said plug valve and forming part of a first valve of said dual valve structure, said member being mounted for rotary and axial movement upon rotation of the valve plug, a second tubular valve element movably mounted in telescopic relation in said first tubular element and having a tubular portion cooperating with said annular valve seat for controlling the flow of gas from said plug valve to said first outlet passageway, said second tubular valve element having a radial passageway providing a predetermined minimum quantity of gas to said first outlet passageway, said second tubular valve element having a portion extending axially beyond the first tubular element and defining an annular valve seat forming part of a second valve of said dual valve structure and controlling the flow of gas to the second outlet passageway, means mounting said tubular members for limited axial movement relative to each other for providing a dwell range in which the second valve is closed and the first is open while a predetermined amount of said axial movement occurs, first spring means biasing said tubular members for said relative movement to said limit, said second dual valve including a cup-like housing the bottom of which constitutes a movable disc valve engageable with said second tubular valve seat, second spring means biasing said housing and disc valve away from said second annular valve seat, an ambient temperature compensating disc in said cup-like housing and movable relative thereto, third spring means between said disc valve portion and said disc, means on said housing limiting movement of said disc relative to said housing, and thermostatically operated means engageable with said disc, said first spring means being the weakest and the third the strongest of the said three spring means.

4. In an ambient temperature compensated thermostatic valve, a thermostatically actuated valve structure including a cup-like housing, the bottom of which constitutes a movable valve disc, a spring mounted within said cup-like housing and having one end engaged with the disc end of the housing, a bimetallic ambient temperature compensating disc movably mounted in said housing engaged by the other end of said spring and movable by it toward the open end of said housing, and said housing having means for limiting the movement of said compensating element by said spring.

5. A valve including in combination, a valve body, a rotatable shut-oft valve element in said body for controlling the fiow of gas therethrough from a gas inlet, said body having first and second outlet passageways, a composite dual valve structure mounted in said valve body in coaxial spaced relation to the inner end of the valve element, said composite valve structure including a first tubular member having an annular valve seat at its end adjacent the valve element and facing away from said element and forming part of a first valve of said dual valve structure, said member being mounted for rotary and axial movement upon rotation of the valve element, a second tubular valve element movably mounted in telescopic relation in said first tubular element and having a tubular portion cooperating with said annular valve seat for controlling the flow of gas from said valve element to said first outlet passageway, said second tubular valve element having a radial passageway providing a predetermined minimum quantity of gas to said first outlet passageway, said second tubular valve element having a portion extending axially beyond the first tubular element and defining an annular valve seat forming part of a second valve of said dual valve struc ture and controlling the flow of gas to the second outlet passageway, means mounting said tubular members for limited axial movement relative to each other for providing a dwell range in which the second valve is closed and the first is open while a predetermined amount of said axial movement occurs, spring means biasing said tubular members for said relative movement, said second valve comprising a movable disc valve engage able with said second tubular valve seat, spring means biasing said disc valve away from said second annular valve seat, and thermostatically operated means engageable with said disc.

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