Thermostat

Claim 2

A thermostat comprising a heat-sensitive element; an electrical conductor positioned in contact with said element, said conductor having at least one surface portion bare of insulation in contact with said element, said element and said conductor being made of metal, said conductor and said element being free of insulation at least at a point of mutual contact to permit efficient heat transfer therebetween by conduction; a power circuit to pass electric current through said conductor to cause it to heat, said conductor being made of spring metal, said conductor being bowed, the spring thereof holding it in pressure contact with said element.

Claim 3

A thermostat comprising: a heat-sensitive element; an electrical conductor positioned in contact with said element, said conductor having at least one surface portion bare of insulation in contact with said element, said element and said conductor being made of metal, said conductor and said element being free of insulation at least at a point of mutual contact to permit efficient heat transfer therebetween by conduction; a power circuit to pass electric current through said conductor to cause it to heat, said conductor being positioned in contact with said element over a relatively small length thereof as compared to its total length so that the metal of said element will not short out a considerable portion of the length of said conductor, said element being everywhere insulated from said power circuit except by contact with the conductor over said relatively small length thereof.

Claim 4

A thermostat comprising: a heat-sensitive element; an electrical conductor positioned in contact with said element, said conductor having at least one surface portion bare of insulation in contact with said element, said element and said conductor being made of metal, said conductor and said element being free of insulation at least at a point of mutual contact to permit efficient heat transfer therebetween by conduction; a power circuit to pass electric current through said conductor to cause it to heat, said conductor being positioned in contact with said element over a relatively small length thereof as compared to its total length so that the metal of said element will not short out a considerable portion of the length of said conductor, said element being everywhere insulated from said power circuit except by contact with the conductor over said relatively small length thereof.

Claim 5

A thermostat comprising: a heat-sensitive element; an electrical conductor positioned in contact with said element, said conductor having at least one surface portion bare of insulation in contact with said element, said element and said conductor being made of metal, said conductor and said element being free of insulation at least at a point of mutual contact to permit efficient heat transfer therebetween by conduction; a power circuit to pass electric current through said conductor to cause it to heat, said element being a bimetal strip wrapped in a spiral; and means to rotate said bimetal strip about the axis of said spiral, said conductor contacting said spiral at a distance from said axis equal to about one-half the radius of the largest spiral turn.

Claim 6

A thermostat comprising: a heat-sensitive element; an electrical conductor positioned in contact with said element, said conductor having at least one surface portion bare of insulation in contact with said element, said element and said conductor being made of metal, said conductor and said element being free of insulation at least at a point of mutual contact to permit efficient heat transfer therebetween by conduction; a power circuit to pass electric current through said conductor to cause it to heat, said element being a bimetal strip wrapped in a spiral; and means to rotate said bimetal strip about the axis of said spiral, said conductor contacting said spiral at a distance from said axis equal to about one-half the radius of the largest spiral turn.

Claim 7

The invention as defined in claim 3, wherein said conductor is resilient, said conductor being shaped to form a spring and positioned in a manner such that the spring action holds the conductor and element in pressure contact with each other.

Claim 8

The invention as defined in claim 3, wherein said element is a strip of two dissimilar metals bonded together to cause movement thereof when said strip is heated or cooled, a switch, said movement being adapted to open and to close said switch, an electrical power supply, a fuel valve having a solenoid winding, and a variable resistor connected in parallel with said conductor, a series circuit including said conductor, said switch, said winding and said power supply all connected in series, said conductor having a circular cross section, means to fix the ends of said conductor rigidly to said circuit, said conductor being made of a nichrome wire spring 0.007 inch in diameter, said wire being bowed, said bow lying in compression against said strip, the spring character of said wire forcing it in pressure contact with said strip, said strip being located sufficiently close to said wire to deform the bow thereof slightly to cause a contact pressure to exist between said wire and said strip, said wire being bare of insulation, said strip also being bare of insulation, the bare metal of said wire lying in contact with the bare metal of said strip, said strip being spaced from said circuit except by the said pressure contact of said wire thereagainst, said strip being wound in a spiral, said wire contacting said spiral at the edge of a least one turn thereof at a position approximately halfway between the spirAl center and the radius of the outside turn thereof, said resistor having a resistance of about 2 1/2 ohms, said wire having a resistance of about one-half ohm, said wire being about 1 inch long, the outside turn diameter of said spiral being less than 1 inch, said wire extending generally in a diametral direction across said spiral touching the same at about the midpoint of said wire.