Themostatic bimetal types
The type of thermostatic bimetal depends on the application and the available space. Elements can be roughly classified into four main groups:
Beams,
Coils,
Disks,
Formed elements.
Beams develop nearly linear motion. Coils (spiral, helical and double-helix coils) Disks move linearly or discontinuously (snap-action).
Formed elements include a wide range of regular or irregular shapes. The U-shape is very widespread. This type of element is employed when the available space will not permit the use of long, flat beams.
Generally speaking, coils are used wherever extensive motion is required, while beams are required for smaller movements to trip operating mechanisms.
Some basic mechanism of bimetal strip:
1. Simple temperature -controlled switch
This type of mechanism is USD for drect switching of an electrical circuit or a mechanical part. When current is passed directly through the element, slow contact motion may result in sparking between the contacts.
2. Counter-acting arrangements
Faster response and higher sensitivity reduces the risk of sparking between contacts in elements with direct electrical heating.
3. Auxiliary thermal switches
The thermostatic bimetal does not form part of the electrical circuit and responds solely to the ambient temperature.
4. Magnetic restraint
A permanent magnet resistrains deflection until the thermostatic bimetal had developed a force sufficient to overcome that of the magnet, thus causing the contacts to spring parts. Conversely, the contacts close when the element has cooled down.
Thermostatic bimetal functions:
The effects of thermostatic bimetal curvature in response to a change in temperature are utilized in practical applications to achieve different aims. These can essentially be described by the following functions: Measuring, limiting, controlling, compensation, pulse-generation, retardation. All these functions overlap to a certain extent so that a particular application may fall under several categories.
Measuring
Temperatures and certain electrical variables and their rate of change can be regulated by calibrated systems.
Examples:
Spiral thermometers, Ammeters
Limiting
Trip functions are required at certain upper or lower limits in order to initiate or to cut out an operation.
Examples:
Automatic circuit breakers
Motor protection switches
Controlling
Within a certain range, functions are cut in or out, or circuits made or broken, in order to maintain a certain average setting.
Examples:
Electric iron controls, Bypass valves
Compensation
A deviation from the initial condition is compensated for by the thermostatic bimetal action.
Examples:
Color television tube compensation, Measuring instruments with compensation for fluctuations in ambient temperature.
Pulse-generation
An operation is triggered at clocked intervals.
Examples:
Flasher relays, Hotplate heating coils
Retardation
An incoming signal (e. G. Current)will only trigger an operation after a defined delay period.
Example:
Thermal relay
Wuhu Boton Automobile Parts Factory is a professional thermostat manufacturer. We specialize in producing four series of products: Bimetal thermostatic coil and disc, heating chambers for engine carburetors, auto generator regulars, various auto glass lifter motor protectors.
Bimetal thermostat consists of two metallic strips, and this part being adjusted the angle causing movement by the hotter temperature, when heated up, it bends in a pre-determined manner, and can be used to monitor, measure and regulate temperature.
Its main application are in thermostats for heating chamber or fan clutch, but they are also used in control devices for instance in automobiles.
