Views: 124 Author: Longway Motor Publish Time: 2022-08-01 Origin: Site
A motor is a rotating electric machine, which converts electrical energy into mechanical energy. It mainly includes an electromagnet winding or distributed stator for generating a magnetic field, the winding and a rotating armature or rotor. Under the action of the rotating magnetic field of the stator winding, a current passes through the effective edge of the stator winding and rotates it under the action of the magnetic field. According to the principle of motor reversibility, if the motor does not produce any changes in its structure, the motor is used as the motor, but also as a generator. It is a machine that converts electrical energy into mechanical energy. Usually the work part of the motor for rotating motion, this motor is called the rotor motor; There are also linear motion, called linear motor.
As shown in Figure 1, the coil is subjected to amperometric force in the magnetic field after energized. According to the left-hand rule, it can be judged that the AD rod is subjected to downward amperometric force, resulting in a clockwise rotating moment, that is, the coil will rotate clockwise. When the coil around 90 °, the coil plane and vertical magnetic field, as shown in figure 2, the assassin ab lever upwards by ampere force, CD rod downward in the ampere force, do not produce torque at this time, but because of inertia, the coil will continue to roll, turn to the position of as shown in figure 3, at the moment if you don't adjust the current direction, ab stem the ampere force up, CD rod by ampere Force downward, the generated torque will hinder the clockwise rotation of the rotor, or even make the rotor rotate counterclockwise, so that the electric machine can not continue to rotate, its rotor will swing back and forth around the balance position.
2 Motor related applications
2.1 Application of electric fan
As is known to all, the working principle of electric fan is motor rotor blades rotates to drive the air circulation, the principle of the motor has been clearer we had studied the principle of the motor in high school, which received electric coil in the magnetic field and the effect of rotating magnetic field force, as a result of the existence of a commutator, coil turns, after half a circle because of inertia, and the connection of copper brush with just now Reverse, which causes the current to reverse, so it can keep spinning, which we know.
The motor of an electric fan is an asynchronous motor, which changes the current through the motor through a series inductor (the governor is a multi-tap inductor). When the current is smaller, the magnetic field generated will weaken, and the force on the rotor wire will be smaller, and the rotor will turn slowly.
There is also a motor winding itself has several sets of taps, with a number of switches to control the power supply connected to different taps out of the line, to achieve control speed. Its principle is: because the frequency of the power supply is fixed, and when the motor is working, the more the number of the stator pole, the slower the speed, so by changing the number of the stator pole when the motor is working, the rotor speed can be changed.
2.2 Application of air conditioners and refrigerators
Refrigerator and air conditioning are using refrigeration compressor to achieve the purpose of refrigeration. The low pressure steam of the refrigerant in the refrigeration system is drawn into the compressor and compressed into high pressure steam and then sent to the condenser. At the same time, the outdoor air inhaled by the axial flow fan flows through the condenser, taking away the heat released by the refrigerant, so that the high-pressure refrigerant vapor condenses into high-pressure liquid.
The high-pressure liquid is sprayed into the evaporator after passing through the filter and throttling mechanism, and evaporates under the corresponding low pressure to absorb the surrounding heat. At the same time, the cross-flow fan makes the air continuously enter the evaporator for heat exchange between the AIDS, and sends the cooled air to the room after heat release. In this way, the air in the room circulates continuously to reduce the temperature.
And the core component of the compressor is the motor.
The basic principle is that a compressor compresses the refrigerant into a high-pressure saturated gas (ammonia or gas Leon), which is then condensed by a condenser. After throttling through the throttling device, it is passed into the evaporator to cool the required cooling medium for heat transfer. For example, the evaporator is connected to each room in the building. The snake tube in the evaporator will exchange heat with the air, and then blow the cool air into the room by blowing.
The refrigerant in the evaporator's snake tube becomes low-pressure steam after heat exchange and returns to the compressor, and then is compressed by the compressor. In this way, the recycling is completed. The heating system works in much the same way, but in reverse. For the current domestic more commonly used fixed frequency air conditioner, the compressor adopts single-phase asynchronous motor 3 and above the air conditioner adopts three-phase asynchronous motor. This kind of motor in the start of the current is large, low efficiency, the biggest deficiency is that the speed can not be adjusted, can not achieve rapid refrigeration (or heat) indoor temperature to maintain constant is dependent on frequent on, power off motive to achieve. The stator windings of the motor are directly in the mixture of refrigerant and lubricating oil, so the requirements for the motor are very high, such as large starting torque, high efficiency, low noise, vibration and impact resistance, insulation materials have better chemical stability (resistance, gas performance), etc.
When the refrigerator is working, the gaseous refrigerant (ammonia or gas Leon and other substances that are easy to be liquefied) is sharply compressed into high temperature and high pressure gas through the compressor, and then enters the condenser (the condenser is equivalent to a heat exchange device, which converts the gaseous refrigerant at high temperature and high pressure into liquid refrigerant at low temperature and high pressure). Through the heat sink to the surrounding air heat source and condense into a liquid. The liquid refrigerant passes through the expansion valve. The so-called expansion valve is a throttling device. Because the refrigerant flowing out of the expansion valve is controlled, the pressure of the refrigerant is reduced and the temperature continues to fall. (refrigerator general substitute capillary expansion valve, because from the bull suddenly to small, tube, also can have the throttling effect) to become a gas liquid two phase, and then enter the evaporation, apparatus (connected to the cold storage), as the refrigerant from the low temperature refrigerator heat absorption of heat, reduce the cold storage temperature and evaporation into steam, become the high temperature and low pressure gas refrigerant continue to cycle back to compressor. Because of this, it is not only impossible to cool a room in the summer with a refrigerator, but it will increase its internal temperature.
3. Application in washing machine
The double bucket washing machine has washing bucket and removing bucket. The washing bucket is powered by a single-phase capacitor motor, driven by the belt deceleration wheel rotation, and frequent positive and negative washing clothes, the bucket is also powered by a single-phase capacitor motor, only a single direction for high-speed rotation to drop off the water in the clothes. Washing timer and dewatering timer commonly used mechanical, electronic or electric three. For the electric type timer, single-phase permanent magnet synchronous motor or single-phase covered pole asynchronous motor is used as power source.
The working principle of the motor of washing machine is shown on the right in Figure 3. The forward and reverse rotation of the motor is controlled by the switch of the washing machine. When the washing machine is connected to the power supply, as long as the switch knob of the washing machine is protected, current will be added to the primary and secondary windings of the motor.
According to the starting principle of capacitor phase dividing motor, when S and S1 are connected, the primary and secondary windings will pass with current. Due to the action of capacitor C, the current passing through the secondary winding is 90° ahead of the electrical Angle of the primary winding, forming a two-phase magnetic field. The motor starts and runs in motion, assuming positive rotation. Because the direction of the rotating magnetic field is related to the order in which the current in the winding reaches the maximum value, so, when S contacts with S, the current flowing into the primary winding is 90° ahead of the current in the secondary winding, the rotating magnetic field is square, to the opposite, and the motor runs in reverse. If S is switched on with S1 and S2, Then the motor will turn and reverse for a while, which is the working principle of the washing machine motor. Therefore, the wave-wheel washing machine can stop Ss by rotating 25~35s and then reversing 25, 35s to stop 5S, so as to rotate periodically during strong washing.
This type of washing machine is driven by an electric motor to rotate the rolls for washing and dehydrating clothes. The motor adopts pole changing two-speed single-phase asynchronous electricity, motive, and single-phase series motor. In addition, in order to shorten the drainage time, the centrifugal drainage pump is generally used for drainage. In the rolling washing machine with drying function, the motor of washing machine equipped with blower is frequently started with load positive and negative rotation.
So the starting torque and the maximum torque are required to be larger.
4. Other applications
Motor structure is simple, easy to control, small size, high efficiency, power can be small or large, widely used in social life. Let me briefly explain how elevators, mobile phone vibrations, and refrigerator compressors work,
When THE ELEVATOR IS WORKING, THE TWO ENDS OF THE TRACTION ROPE are connected TO THE CAR AND the PAIR of weights respectively, which are wrapped around the traction wheel and the guide wheel, and the traction motor drives the traction through the speed reducer, and the wheel rotates. The traction force generated by the friction between the traction rope and the traction wheel realizes the lifting movement of the car and the pair of weights, so as to achieve the purpose of transportation.
Mobile phone vibration is the use of eccentric motor, that is, the head of the ordinary motor is equipped with a CAM, and the center of gravity of the CAM is not in the motor shaft, in rotation, due to the effect of centrifugal force, the mobile phone held in the mobile phone is vibration
As the core driving component of electromechanical energy conversion of household appliances, motor is widely used in the field of household appliances. The performance index of motor is directly determined.
The performance of household appliances also determines the service life of household appliances. The future development trend of small motors for all kinds of household appliances according to the use of small motors is not consistent, not the same, mobile phones, BP machines and other communication appliances motor, electric toys motor requirements to miniaturization, thin direction. The development direction of small motor for computer peripherals and office automation equipment is high speed, high reliability, low noise, low vibration and long life. For example, spindle motor for hard disk drive is used. When rotating at high speed, the head and platter for reading and writing function are only 0.1 -0.3 micron-high, the main shaft motor for optical disk drive is required to work for 5000 hours under rated load conditions, the motor speed of laser printer is up to 1000~ 3000R /min, air conditioning, washing machine, refrigerator, vacuum cleaner, etc., the development direction of small motor for household appliances is energy saving, low noise, intelligent