Hair dryer: it is composed of a group of electric heating wires and a small fan. When powered on, the heating wire will generate heat, and the wind from the fan will become hot air after passing through the heating wire. If it's just a small fan rotating, and the heating wire is not hot, then it's just the wind that blows out, not the heat. According to the type of motor it uses, it can be divided into AC series excitation type, AC cover pole type and DC permanent magnet type. The advantages of series blower are large starting torque, high speed, suitable for manufacturing high-power blower; the disadvantages are large noise, commutator has certain interference on telecommunication equipment. The advantages of the shaded pole blower are low noise, long service life and no interference to the telecommunication equipment; the disadvantages are low speed, poor starting performance and heavy weight. The advantages of permanent magnet hair dryer are light weight, high speed, simple manufacturing process, low cost, good quality and low price. Although there are many kinds of blowers, their structures are the same and the same. They are all composed of shell, handle, motor, fan blade, electric heating element, wind shield, switch, power cord, etc.

Effect:
1. Shell. It protects the internal parts and is also the external decorative parts.
2. Motor and blades. The motor is installed in the shell and the fan blade is installed on the shaft end of the motor. When the motor rotates, air is drawn in from the air inlet and blown out from the air outlet.
3. Electric heating element. The electric heating element of the hair dryer is made of electric hot wire, which is installed at the air outlet of the hair dryer. The air discharged by the motor is heated by the electric hot wire at the air outlet and sent out as hot air.
Some blowers are equipped with thermostats near the electric heating elements. When the temperature exceeds the predetermined temperature, the circuit is cut off to play a protective role.
4. Wind shield. Some blowers have round windscreens at the air inlets to regulate the air intake. A blower without a round wind shield can cover a part of the air inlet with a piece of paper, and the air inlet can also be adjusted. If the air intake is small, the wind will be hot. If the air intake is large, the wind will not be too hot. It should be noted that the air outlet cannot be blocked too much, otherwise the motor will be damaged or the electric heating elements will be burned due to the high temperature.

5. Switch. Generally, there are three positions of "hot air", "cold air" and "stop" on the blower switch. Usually, white means "stop", red means "hot air", and blue means "cold air". The electric heating elements of some blowers are composed of two or three sections of electric heating wires, which are used to adjust the temperature and controlled by the selection switch. With the reform and gradual improvement of the blower performance, a group of constant temperature automatic control elements are connected in series on the heating elements of the blower at home and abroad, which can automatically switch on the circuit under the normal working condition of the blower and automatically cut off the circuit in case of special conditions (such as overheating of the heating elements). In the selection of the shell material of the air duct, the metal (such as copper or cold-rolled iron plate) was also used in the past, and the thermoplastic engineering materials (mainly polycarbonate, modified polyphenylene, modified polypropylene, etc.) were used instead.
In principle, the blower directly drives the rotor of the motor to drive the blades to rotate. When the blades rotate, the air is drawn in from the air inlet, and the resulting centrifugal air flow is blown out from the front mouth of the air duct. When the air passes through, if the heating wire installed on the heating bracket in the air nozzle has been electrified and becomes hot, the hot air will be blown out; if the selection switch does not electrify the heating wire, the cold air will be blown out. Blower is to achieve the purpose of drying and shaping. The selection switch on the handle of the blower is generally divided into three gears, namely, the off gear, the cold wind gear and the hot wind gear, with the white, blue and red signs attached. The handle of some blowers is also equipped with a motor speed regulating switch to select the size of air volume and the temperature of hot air. The back or side of the shell of various kinds of hair dryer is equipped with a rotatable circular air adjusting cover, which can be rotated to adjust the cross-section size of the air inlet, so as to adjust the conveying wind speed and the temperature of the hot air. According to the way of use, there are hand-held and pedestal blowers. The pedestal hair dryer can be put on the table or hung on the wall for use, and can blow for yourself. According to the way of air supply, there are centrifugal blower and axial-flow blower. The centrifugal type relies on the motor to drive the blades to rotate, so that the air entering the blower can obtain the inertial centrifugal force and exhaust air continuously. Its disadvantage is that the exhaust air does not flow through the motor completely, so the temperature of the motor is higher; the advantage is that the noise is lower. The axial-flow motor drives the blades to rotate, pushes the air entering the blower to flow axially, and continuously exhausts the air outwards. Its advantage is that all the exhaust air flows through the motor, the motor has good cooling conditions, and the insulation is not easy to age; its disadvantage is that the noise is large. According to the materials used in the shell, there are metal type blowers and plastic type blowers. The metal blower is durable and can withstand high temperature. Plastic hair dryer is light in weight, good in insulation, but easy to aging, and poor in high temperature resistance.

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