FOSHAN TONGBAO HUALONG CONTROLS CO.,LTD

The leading temperature control solutions and services provider

Add: No.41,Huijin Rd., BainiSanshui Foshan, Guangdong ,China
Tel : 86-757-87575702
Post : 528131
Fax : (86)757-87655136
Email :dengxiaoshun@fstb.com.cn

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Working principle of bimetallic heat protector
    Bimetallic heat protector is a thermostat with bimetallic sheets as a temperature sensitive component. It is combined with two alloys with different thermal expansion coefficients to convert the temperature change into mechanical movement. The coefficient of thermal expansion is called the active layer, and the coefficient of thermal expansion is called passive layer. At normal temperature, the length of the two metal is equal, and the internal stress is not. When the temperature rises, because the two kinds of metal thermal expansion properties are different, even the same elevated temperature, thermal expansion coefficient of material elongation much bigger, and two kinds of materials and has been fixed together, causing the internal bimetal temperature pressure, active layer to the passive layer side bending deformation occurs. In general, the low expansion layer uses Ni-Fe alloy, and the high expansion layer uses Ni-Mn-Cu alloy or Fe-Ni-Cr alloy, and various materials can be selected according to different expansion coefficient. The bimetal plate is made into a dish shape, and when the temperature is raised to the preset temperature, the center of the bimetallic plate can be turned over in time, and when the temperature drops, it can recover the original position, so as to make the component that converts the temperature into the mechanical movement.
     As shown in the diagram, when the temperature rises, the center of the bimetallic plate moves slowly from the "0" point to the "A" point, and when the velocity reaches the "B" point, the center instantaneous time of the bimetallic plate is turned from "B" point to "C" point. When the temperature drops, the center of the bimetallic plate moves slowly from the "C" point to the "E" point, and when the "F" point arrives, the center of the bimetallic plate flips again to the "G" point (restitution). Double metal sheet made of a certain shape, according to the G - > A - > B - > C - > E - > F - > G Cycle repeated action. From the change of temperature is B->C off temperature (Open Temp), the temperature change F - > G is (Close Temp), the recovery temperature off temperature and recovery temperature difference between called depressor. Using the above rebound characteristics, the bimetal chip temperature switch is called Thermostat.
    When the electric appliance works normally, the bimetallic piece is in the free state, the contact is in the closed / disconnected state, when the temperature reaches the action temperature, the bimetallic sheet is heated to generate the internal stress and moves rapidly, opening / closing contacts, cutting off / connecting the circuit, so as to play a temperature control function. When the appliance is cooled to reset temperature, the contacts are automatically closed / opened to resume normal working condition.
    The bimetal thermal protector is widely used in washing machine, dishwasher, dryer, Soybean Milk machine, mixer, refrigerator, air conditioner, microwave oven, water heater, water dispenser, electric coffee pot, electric boiler, office equipment, automobile seat heaters and other electric appliances.


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