Who can help me with my knowledge about popular science fans?

A fan refers to an appliance used to generate wind and cool down in hot weather. An electric fan is a device that is driven by electricity to generate airflow. The fan inside turns into natural wind after being electrified to achieve the effect of enjoying the cool.

Time of invention

The mechanical fan comes from the roof. 1829, an American named james byron, inspired by the clock structure, invented a mechanical fan that can be fixed on the ceiling and driven by a clockwork. The cool wind brought by the rotation of the fan blades is refreshing, but it is very troublesome to climb the ladder and wind it up.

1872, a Frenchman named Joseph invented a mechanical fan which was started by a clockwork turbine and driven by a gear chain device. This kind of fan is much more exquisite than the mechanical fan invented by Byron, and it is more convenient to use.

1880, American Shule first installed the blade directly on the motor, and then connected to the power supply. The blades turned rapidly, and a cool breeze came head on. This is the first electric fan in the world.

structure

Rotor: composed of magnets, blades and shafts; Stator: composed of silicon steel sheet, coil and bearing; Control circuit: the N.S. pole of the IC induction magnet controls the conduction of its coil through the circuit to generate internal excitation and make the rotor rotate. Type: axial fan, DC fan.

Option: total cooling demand q = CP mAt = D CP CFM △ T

Basic structure

It mainly consists of four parts.

Rotor: composed of magnets, blades and shafts;

Stator: composed of silicon steel sheet, spool and bearing;

Control circuit: IC induction magnet;

The south magnetic pole controls the conduction of its coil through the circuit, which generates internal excitation and makes the rotor rotate.

principle of operation

Basic structure of fan

The main components of the electric fan are: AC motor. Its working principle is that the electrified coil is forced to rotate in the magnetic field. The conversion form of energy is: electric energy is mainly converted into mechanical energy, and at the same time, due to the resistance of the coil, some electric energy will inevitably be converted into heat energy.

When the electric fan is working (assuming that there is no heat transfer between indoor and outdoor), the indoor temperature will not decrease, but will increase. Let's analyze the reasons for the temperature rise together: when the electric fan is working, because there is current passing through the coil of the electric fan and the wire is resistive, it will inevitably generate heat and release heat, so the temperature will rise. But why do people feel cold? Because there is a lot of sweat on the surface of human body, when the electric fan works, the indoor air will flow, so it can promote the rapid evaporation of sweat, and combined with "evaporation needs to absorb a lot of heat", people will feel cool.

Mode of operation

1. parallel fan: the wind pressure of parallel double fans is unchanged, but the air volume will increase. With the increase of air volume, the heat dissipation effect is enhanced. If the cooling power is too small in design, you can consider adding a fan to solve it.

2. Series fans: The result of series fans is that the wind pressure increases, but the air volume remains unchanged. This method can't solve the problem of heat dissipation, and it is usually used when the near wind resistance is too large to ensure the air volume.

material circumstance

In order to reduce the low noise during use, we must pay attention to the following points:

System impedance: airflow resistance will cause airflow noise.

Turbulence: Due to the poor design of the flow passage, high-frequency noise will appear in the air turbulence. If the flow passage is not improved, it is difficult to improve it qualitatively.

Speed and size of the fan: The faster the speed of the fan, the better the heat dissipation effect; The larger the fan size, the greater the air volume and the better the heat dissipation effect. Fan rotation

The higher the speed, the louder the noise, and the larger the size, the louder the noise.

Temperature rise: after the temperature rises, the temperature difference decreases and the heat dissipation effect decreases.

Vibration: Vibration will increase the noise of the fan, reduce its service life and speed.

Voltage fluctuation: voltage fluctuation will cause the fan speed to change, making the work unstable and generating extra noise.

Design considerations: Other design requirements must also be considered to ensure the heat dissipation effect.

(1) Air intake distance of the fan: the distance of 3 ~ 5 mm is the most basic point.

3 mm-The efficiency of the fan is 80%.

4 mm-The efficiency of the fan is 90%.

5 mm—The efficiency of the fan is 100%.

(2) Different air inlets and outlets will cause great changes in airflow resistance. Of course, the greater the opening of the air inlet and outlet, the better.

(3) Do not place obstacles (such as chips, interfaces, etc.) near the air inlet of the fan, otherwise it will reduce the air volume of the fan.

(4) It is best to use rubber instead of metal screws to fix the fan, so as to avoid vibration.

(5) Space design of the fan. For the efficiency and noise of the fan, the distance between the fan blade and the fan shell must be 5 ~ 10 mm, and for better efficiency, the fan blade must be close to the tongue.

kind

According to the motor structure, it can be divided into single-phase capacitive, single-phase shaded pole, three-phase induction, DC and AC-DC series commutator fans.

According to the use, it can be divided into: household electric fan and industrial exhaust fan.

According to the classification of inlet and outlet air, it can be divided into axial fan, centrifugal fan and cross-flow fan.

(1) Household electric fans: ceiling fans, desk fans, floor fans, wall fans, ceiling fans, ventilation fans, box fans, air-conditioning fans (i.e. air coolers), etc. There are table fans that shake their heads, and there are also box fans; Some floor fans shake their heads and turn pages. There is also a small wind electric fan, which is specially hung in the mosquito net. When you sleep at night in summer, the breeze blows gently as soon as you turn it on, so that you can sleep well and not get sick. Warm reminder, the fan is easy to adhere to dust when working in the air, so it is best to cut off the power supply and clean it in time during use.

(2) Industrial exhaust fan: mainly used for forced air convection. After the electric fan is used for a long time, it is easy to get a lot of dust under the fan blades. This is because when the electric fan is working, the blades are charged with static electricity due to friction with air, and charged objects can attract light and small objects, thus absorbing the fine dust floating indoors.

Selection skill

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Desktop and floor options

These two kinds of electric fans are generally divided into standard popular type and electronic luxury type. The former is characterized by simple structure, convenient operation and low price, and generally only has two functions of speed regulation and wind direction change; The latter is characterized by complex and changeable functions and luxurious and exquisite modeling. Consumers can decide for themselves whether it is practical or practical, decorative and luxurious.

Certification: when buying electric fans, consumers should read the instructions clearly to see if they have obtained the compulsory certification, quality system certification, inspection standards and other certifications; At the same time, the promotion of "environmental protection and low carbon" depends on whether it meets the national energy efficiency standards.

Low noise: the main part of the electric fan that makes noise is the motor. When choosing an electric fan, be sure to listen to whether there is noise when the motor is running and see if it is shaking and stable when it is running. A good motor can make you only hear the whisper of the wind in a quiet environment, and ultra-quiet air supply is a good fan.

No odor: the odor is the odor generated by the insulating paint on the copper sheet of the electric fan during operation. When buying an electric fan, you should smell it to see whether the paint is environmentally friendly and whether it passes the quality inspection, so that you can feel the coolness of the wind in the fresh air.

Electrical safety: The safety requirements of electric fans are detailed in national standards, and consumers can also conduct simple tests. Qualified fans, the fingers of adults can't touch the leading edge of the fan blade through the mesh cover, and families with children should choose electric fans with dense mesh cover.

apterous

Principle: In fact, the air is not compressed. The principle is similar to the wing of an airplane. The wall thickness of the ring above it is uneven, that is to say, one side of the ring is relatively large in diameter and the other side is relatively small, so that the air blown out from the bottom will weaken the surrounding air pressure after passing through the ring, thus driving the surrounding air and enhancing the air flow. This design is not only beautiful, but also very practical. Because the driving air below does not need too much flow, the noise is very low. Because the driving air drives the surrounding air, the air volume is higher than that of ordinary electric fans. In addition, ordinary fans use blades to cut air to promote airflow, so they are uncomfortable. This fan has a continuous airflow, so it is more comfortable. Also, this fan is not top-heavy, so it is relatively stable.

Please click to enter a picture description.

The distance between the fan and people is preferably controlled at more than 2 meters. If you don't have much room at home, you can choose to blow a fan against the wall and let the wind reflect.

Use and maintenance

Read the instructions carefully before use, and fully grasp the structure, performance, installation, use and maintenance methods and precautions of the electric fan.

Desktop and floor electric fans must use three-core plugs and sockets with safety grounding wires; The ceiling fan should be installed at a higher position on the ceiling without grounding wire.

The blades of electric fans are important parts, and they must be protected to prevent deformation, whether they are installed, disassembled, scrubbed or used.

When operating the switches, keys and knobs of various functions, you should not move too fast or too fast, nor should you press two keys at the same time.

The ceiling fan speed control knob should be rotated slowly and sequentially, not in the gear position, otherwise it will easily cause the ceiling fan to heat up and burn the machine.

Oil pollution or dust accumulation of electric fans should be removed in time. Do not use gasoline or strong alkali solution to wipe, so as not to damage the function of surface paint parts.

If the electric fan is hot, has abnormal burning smell, shakes its head seriously, slows down, etc. Do not continue to use it, and cut off the power supply in time for maintenance.

Before collecting electric fans, thoroughly remove the oil stains and dust on the surface, wipe them with a dry soft cloth, and then wrap them with kraft paper or clean cloth. The storage place should be dry and ventilated to avoid squeezing.

Collection and preservation

When the weather turns cold, the electric fans used in summer should be collected and preserved, and the following work should be done specifically:

1. Disassemble the parts correctly according to the requirements of the electric fan circuit diagram. When operating, first open the net cover clip, unscrew the fastening bolt on the fan blade sleeve and take off the fan blade; Unscrew the four nuts fixing the rear mesh cover, remove the gasket and the rear mesh cover, and replace the nut gasket.

2, do a good job of electroplating maintenance. First, use a soft cloth to wipe off dust, stains and water vapor on the plated parts, and then apply a thin layer of engine oil for protection.

Please note that it must be wiped clean before oiling, otherwise the water will not evaporate easily after oiling, which may cause corrosive dust spots and rust on the plated parts.

3, do a good job in the maintenance of paint parts. Wipe with a soft cloth. If the stain on it is not easy to wipe off, you can scrub it with soapy water with less alkali content or wipe it with a small amount of kerosene, then clean it and dry it. After removing the blade, wrap it in soft paper and put it between the front and rear mesh covers to avoid the blade angle deformation.

4. Maintenance of other components. The power cord should not contact with harmful gases, such as mosquito-repellent incense and gas. Otherwise, it will change color and even cause an accident. The motor bearing is an oil-bearing copper bearing. In order to prevent it from losing oil, a proper amount of engine oil can be injected into the oil injection hole. The rocking knob is initially placed in the rocking position to prevent the compression spring from being in an uncompressed state.

5. In addition, before the fan head is put into plastic bags and cartons, it is best to run for more than ten minutes without load, and then pack it after the fan head is completely cooled, so that the motor can be in a dry state in winter.

Clear noise

First, lubricate the bearing.

Bearing is the most important part of fan transportation. After a long time, lack of lubricating oil, high-speed rotation will produce noise. So, we just need to drop a few drops of lubricating oil on the fan bearing, if we don't use a sewing machine instead. But be careful not to use edible oil instead, because its particles are relatively large and it is easy to damage the bearing.

Second, fix the fan blades.

Vibration noise is also an important part of fan noise, because the blade is loose on the bearing and the bearing wear causes the gap to become larger, so it is only necessary to remove the fan and tighten the screws, and it will not vibrate again after it is firmly fixed.

Thirdly, grinding the fan blades.

In addition, when using a poor quality cooling fan, due to process defects, the center of gravity of the fan blade may not be on the shaft, forming an "eccentricity". After a long period of use, the "eccentricity" of the fan will become more and more serious, which will not only produce noise, but also seriously damage the CPU. In this regard, * * * can be removed and hung in its center with a thin iron wire. When it is at rest, see which direction it sinks. Grind the sinking end on the grinding wheel several times, then test and install it until the fan can be in a horizontal position.