| 摘要 |
PURPOSE:To protect switch contacts of an electric coffee boiler extracting high temperature coffee by designing switches so that the contacts of the higher input voltage circuit are closed with priority in switching contacts of a heater circuit and switching contacts of a motor circuit. CONSTITUTION:A switch 8 is composed of an operating rod 16 closing or opening the circuit by the simultaneous action of both contacts 18 of a motor circuit and contact 19 of a heater circuit and an operating rod 17 closing or opening only the contact 19 of the heater circuit. The distance (x) between contacts on opening of the contacts 15 is designed to make shorter thus the distance (y) between contacts on opening of the contacts 14. When the operating rod 16 is transferred by the distance A, the currents 0.5A, 0.8A are conducted respectively in both motor circuit and heater circuit. Since the distance (x) on opening of the contacts 15 is set shorter than the distance (y) on opening of the contacts 14, the contact 19 is deformed and a larger contacting force than the contact 14 is added in the contact 15 conducting a large current. In this way, it can prevent arc from generating between contacts and prevent the easily heated contact 15 from increase of temperature. |
