Thermostat
A thermostat for cooking appliances powered by gas includes a body defining an inlet conduit and an outlet conduit that receive a gas flow from a supply source and to supply it to a gas burner, and a chamber having a substantially cylindrical shape that is in fluid communication with the inlet conduit, and also with the outlet conduit either directly, through a main opening formed at one end thereof, or indirectly, through a secondary conduit formed in the body of the thermostat. The gas flows into the outlet conduit bypassing the main opening. A one-piece valve adjusting the gas flow rate is coaxially fitted in the chamber and guided by its peripheral walls. These features make the structural configuration of the thermostat body and its conduits is much more compact, functional and less expensive than in thermostats known in the art.
1. A thermostat ( 10 ) for cooking appliances powered by gas, said thermostat ( 10 ) comprising:
a body ( 20 ), within which there are formed,
an inlet duct ( 23 ) and an outlet duct ( 24 )) respectively configured to receive a gas flow from a supply source and to supply said gas flow to a gas burner,
a chamber ( 25 ) with a substantially cylindrical shape disposed in fluid communication with said inlet duct ( 23 ), wherein said chamber ( 25 ) is also disposed in fluid communication with said outlet duct ( 24 ) either directly through a main opening ( 70 ) formed at one end thereof, or indirectly, through a secondary duct ( 71 ) formed in the body ( 20 ) of the thermostat ( 10 ) and flowing into the outlet duct ( 24 ) bypassing said main opening ( 70 ), said main opening ( 70 ) and secondary duct ( 71 ) being respectively dimensioned for a maximum and a minimum flow rate of gas; and
a valve ( 80 ) having a cylindrical shape and configured to regulate the flow rate of the gas,
wherein said valve ( 80 ) is a one-piece valve fitted in the chamber ( 25 ) coaxially thereto and movable between a first position, wherein the main opening ( 70 ) is completely clear, thereby allowing passage of the gas flow toward the outlet duct ( 24 ), and a second position, wherein the main opening ( 70 ) is completely closed by the valve ( 80 ) and the gas flow reaches the outlet duct ( 24 ) through the secondary duct ( 71 ) only,
wherein said valve ( 80 ) comprises a pair of flanges ( 81 , 82 ) formed at free ends of said valve, a first flange ( 81 ) facing the main opening ( 70 ) of the chamber ( 25 ) and having a diameter dimensioned to close the main opening in said second position, and a second flange ( 82 ) closing the chamber ( 25 ) at an opposite end thereof, said second flange ( 82 ) being provided with a circumferential groove configured to receive a sealing element ( 83 ) of the valve ( 80 ) to prevent an escape of the gas from the chamber ( 25 ), diameters of the first and the second flanges ( 81 , 82 ) substantially corresponding to a diameter of the chamber ( 25 ), and
wherein said inlet duct ( 23 ) and said secondary duct ( 71 ) are in fluidic communication through said substantially cylindrical chamber ( 25 ) at any axial position of said valve ( 80 ).
2. The thermostat ( 10 ) according to claim 1 , further comprising a thermostatic bulb ( 50 ), said thermostatic bulb ( 50 ) comprising a probe ( 51 ) configured to be inserted in a compartment to be heated and an expandable member ( 53 ) connected to said probe ( 51 ) through a conduit ( 52 ), a thermally expandable fluid medium being provided inside the conduit, said expandable member ( 53 ) being operably connected to the valve ( 80 ) at said second flange ( 82 ).
3. The thermostat ( 10 ) according to claim 2 , wherein an end of the chamber ( 25 ) is formed opposite to an end where the main opening ( 70 ) is provided, the chamber ( 25 ) being partially closed by a lid ( 26 ) fixed to the body ( 20 ), and wherein the valve ( 80 ) comprises a drive portion ( 84 ) formed on the second flange ( 82 ), said drive portion ( 84 ) being in contact with the expandable member ( 53 ) of the thermostatic bulb ( 50 ).
4. The thermostat ( 10 ) according to claim 3 , wherein, in an assembled configuration of the thermostat ( 10 ), the valve ( 80 ) is biased by a spring away from the main opening ( 70 ), and wherein said drive portion ( 84 ) protrudes from the body ( 20 ) through a circular opening formed in said lid ( 26 ).
5. The thermostat ( 10 ) according to 1 , wherein the secondary duct ( 71 ) has a U-shape whose straight branches extend parallel to each other transversally to the chamber ( 25 ) and are connected to each other by an elbow portion, and wherein the thermostat ( 10 ) further comprises a needle valve ( 90 ) inserted into a partially threaded hole formed in the body ( 20 ), said needle valve ( 90 ) crossing the secondary conduit ( 71 ) at said elbow portion.
6. The thermostat ( 10 ) according to claim 5 , wherein the elbow portion of the secondary duct ( 71 ) has a frustum-conical shape configured to receive in abutment a corresponding frustum-conical end portion ( 91 ) of the needle valve ( 90 ).
7. The thermostat ( 10 ) according to claim 6 , wherein the needle valve ( 90 ) further comprises an axial bore ( 92 ) formed at the frustum-conical end portion ( 91 ) of the needle valve, a plurality of radial holes ( 93 ) being formed in a cylindrical portion contiguous to the frustum-conical end portion ( 91 ) of the needle valve, said radial holes ( 93 ) being disposed in fluid communication with said axial bore ( 92 ).
8. The thermostat ( 10 ) according to claim 1 , further comprising a thermoelectric safety device ( 60 ) configured to block the gas flow through the body ( 20 ), said thermoelectric safety device ( 60 ) being operably connected to the inlet conduit ( 23 ) at an elbow portion ( 230 ) thereof.
9. The thermostat ( 10 ) according to claim 8 , further comprising a drive rod ( 100 ) configured to enable actuation of the thermoelectric safety device ( 60 ), said drive rod ( 100 ) being inserted in a hole formed in the body ( 20 ) of the thermostat ( 10 ) and protruding from the body ( 20 ) through a cover ( 30 ) thereof.
10. The thermostat ( 10 ) according to claim 9 , wherein the drive rod ( 100 ) comprises a thrust member ( 110 ) telescopically inserted therein and urged away therefrom by a helical spring, said thrust member ( 110 ) being arranged in the inlet duct ( 23 ) at a shoulder ( 231 ) of the elbow portion ( 230 ) and comprising a flange ( 111 ) provided with a gasket ( 112 ) configured to seal the inlet conduit ( 23 ) at said shoulder ( 231 ), the thrust member ( 110 ) being operably connected to the thermoelectric safety device ( 60 ) in an assembled configuration of the thermostat ( 10 ).
11. The thermostat ( 10 ) according to claim 10 , further comprising a coupling member ( 40 ) configured to enable connection of a knob for ignition of the gas burner and temperature regulation, said coupling member ( 40 ) being rotatably coupled to said cover ( 30 ) of the body ( 20 ) of the thermostat ( 10 ) and operably connected to the valve ( 80 ) through an expandable member ( 53 ) of a thermostatic bulb ( 50 ).
12. The thermostat ( 10 ) according to claim 11 , wherein the coupling member ( 40 ) comprises a cam profile ( 41 ) formed on a surface of the coupling member, the cam profile facing said cover ( 30 ) and being configured to engage the drive rod ( 100 ) only beyond a predetermined angle of rotation of the rotatable coupling member ( 40 ).