| 摘要 |
In appliances such as domestic irons, power is supplied cyclically to the heating means in response to a thermostatic control. A switch unit (100) placed in the power supply interrupts the power after a given number of cycles. As power passes cyclically through the unit a bimetal (106) sequentially deflects under the heating effect of the current and then returns to its original position as it cools. The movement of the bimetal as it cools is transmitted to an actuating member (117) via a rack (116) and pawl (114), whereby after a given number of cycles, the member (117) will act on snap action blade (110) to open contacts (112, 104). A rocker arm (120) is mounted on the member (117) so that in one orientation of the switch, it will operate the blade 110 in a much smaller number of cycles. |
