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(11) | EP 0 831 506 A3 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Thermostat |
| (57) A thermostat comprises a tube (10) with a switch assembly (12) mounted at a first
end of the tube. A rod (14) extends within the tube and is secured to it adjacent
its second end (16). The rod (14) has a coefficient of thermal expansion different
from that of the tube (10) and is operatively coupled to the switch assembly (12)
so as to cause the switch assembly (12) to change state in reaction to a change of
temperature of the tube (10). There is carried on the rod (14) a first supporting
member (42) formed from a material of a high melting point and a second supporting
member (44) formed from a material with a melting point below that temperature which
would be dangerous if exceeded in use. A spring (50) is trapped in compression between
the first and second supporting members (42,44). An actuating assembly (60,62,64))
is operable under the action of the spring (50) on its release in the event of the
second supporting member (44) melting, to cause the switch assembly (12) to change
state so as to prevent further heating. |