Sole plate temperature control including differential expansion

An iron comprising:

• a sole plate which expands and contracts under heating and cooling;
• a flexible low expansion reference member extending over a major portion of the length of the sole plate, the reference member being held in tension and having two ends, one end of said reference member being attached to the sole plate at a first point, and the other end of said reference member being attached at a second point which is spaced from the first point to switch means activated by relative movement of said sole plate and said reference member occurring as a result of the expansion and contraction of the sole plate relative to the reference member;
• means for varying the spacing between the said first and second points of attachment of the ends of the reference member to the sole plate and switch means respectively and thereby varying the temperature at which the switch means will operate;
• and wherein said reference member is fixedly retained at one of its ends by a fusible member which melts in the event of the sole plate overheating to release the reference member, said reference member cooperating with a set of contacts so as to open said contacts when so released, thereby interrupting the power supply to a heating element of the iron.

An iron comprising:

• a sole plate which expands and contracts under heating and cooling;
• a flexible low expansion reference member extending over a major portion of the length of the sole plate, the reference member being held in tension and having two ends, one end of said reference member being attached to the sole plate at a first point, and the other end of said reference member being attached at a second point which is spaced from the first point to switch means activated by relative movement of said sole plate and said reference member occurring as a result of the expansion and contraction of the sole plate relative to the reference member;
• means for varying the spacing between the said first and second points of attachment of the ends of the reference member to the sole plate and switch means respectively and thereby varying the temperature at which the switch means will operate;
• and thermal protection means for interrupting the power supply to a heating element of the iron in the event that the sole plate overheats, said thermal protection means including a thermally deformable member resiliently biased into thermal contact with a portion of the sole plate by a spring mechanism, said deformable member being arranged to deform at a critical predetermined temperature so as to release said spring mechanism and open a set of contacts.