In fact, there are still many electrical equipment equipped with rotary switches, such as desktop electric fans, ceiling fans, range hoods and other electrical appliances have rotary switches. Electronic products using rotary switches have the advantages of high efficiency, simple structure and convenient use, which also provide great convenience for our life. Electric fan is a representative household appliance. The use effect of fan rotary switch is very good. Next, I will introduce the principle and maintenance method of electric fan rotary switch.
1、 Principle of fan rotary switch:
Change the duty
cycle of the output square wave to adjust the average current power on the load
to change between 0-100%, and thus change the load and light brightness / motor
speed. Pulse width modulation (PWM) is used to realize dimming and speed
regulation. For example, when 50% of the square wave is output, the output
energy power of the pulse width modulation (PWM) circuit is also 50%, while the
power supply must provide more than 71% of the output power, of which 21% is
consumed in the voltage drop and heat consumption of the resistance. The
resistor consumes most of the energy, and the rest is the output energy, so the
conversion efficiency is very low.
2、 Maintenance method of rotary switch of fan:
1. When checking
the rotary switch, first check whether the connection between the rotary switch
and each wire is good, and then check whether the return spring force of the
rotary switch fails.
2. If there is
desoldering or false welding between the rotary switch and the conductor, use
an electric soldering iron to re weld; If the elastic force of the return
spring fails, it is necessary to replace the return spring with the same
elastic force. In order to replace the new return spring, and after the
replacement, the fixing rod shall be reinforced again to prevent the spring
from being fixed firmly and falling off easily after the replacement of the new
return spring.
3. Check whether
the control knob of fan rotary switch is worn. If the control knob is worn,
just replace it. Then disassemble the speed regulating switch, check whether
the internal control rod and inclined edge are deformed and seriously worn, and
then check whether the rotating shaft is broken. If the internal components of
the speed regulating switch are damaged, replace it. If the control rod is
deformed, just recalibrate it.
4. Then check
whether the moving piece of the rotary switch is deformed and whether the fixed
piece is seriously worn or loose. If the moving piece is deformed, it can be
corrected by pointed nose pliers; If the stator is loose, it needs to be fixed
again; If the stator is seriously worn, it needs to be replaced again. Among
them, the rotary switch also includes a rotary elastic device to check whether
the spring force in the rotary elastic device is invalid and cracked.
The above is the
specific introduction of the principle and maintenance method of the fan rotary
switch, because the fan rotary switch belongs to the electronic switch, and the
fan rotary switch adopts the electronic circuit or microprocessor chip. The use
of fan rotary switch can change the number of stages, voltage, current and
frequency of the motor, which can well regulate the speed of the motor and
control the service performance of the motor. If the rotary switch fails and
the wind speed cannot be adjusted, the rotary switch needs to be overhauled at
this time.
