| 摘要 |
<p>A refrigerator or freezer of the type having an electrical defrost heater associated with its evaporator has a control unit including a switch device with a first pair of contacts (16, 17) controlling the cyclic cutting-in and cutting-out of a compressor motor and a second pair of contacts (16, 18), sharing a common movable contact (16) with the first pair, controlling the periodic energization of the defrost heater. Closure of the second pair of contacts is normally obstructed by a stop member (22) which is movable by a ratchet mechanism (24, 26) or other means responsive to a predetermined number of switching cycles of the compressor motor to a defrost position in which a notch (23) in the stop member (22) permits movement of the movable contact to close the second pair of contacts (16, 18) and energize the defrost heater.</p> |
