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After using a fan for a period of time, it often experiences a significant decrease in speed, weakened air blowing force, and accompanied by increased operating noise. What are the core reasons for this phenomenon? How to solve and prevent it targetedly?
As the core power component of a fan, the operating status of the fan motor directly determines the fan’s performance. The combined phenomenon of “decreased speed + increased noise” is essentially caused by increased operating resistance of the motor, reduced power output efficiency, and intensified vibration due to component wear or fit deviation. Specifically, it can be divided into three core reasons, with corresponding solutions and preventive measures as follows:
I. Analysis of Core Reasons
1. Wear of Motor Bearings or Lubrication Failure (Most Common Reason): The rotor of the fan motor is supported by bearings for rotation. Whether it is a traditional oil-impregnated bearing or a ball bearing, long-term operation will lead to the consumption and aging of internal lubricating oil, or bearing wear due to dust entry. When lubrication is insufficient, the friction force of the rotor rotation will increase significantly. The motor needs to consume more electrical energy to overcome the resistance, resulting in a decrease in the actual output speed. At the same time, the internal gap of the worn bearing becomes larger, and the rotor will produce eccentric vibration during rotation, which in turn causes obvious “buzzing” or friction noise. The noise will increase with the aggravation of wear.
2. Aging or Local Short Circuit of Motor Windings: The motor winding is the core component that generates electromagnetic torque. It is made of copper wire winding and wrapped with an insulating layer. During long-term use, the insulating layer will age and break due to high temperature, humidity or voltage fluctuation, which may lead to local short circuit of the winding. After the short circuit, the number of turns of the winding decreases, the electromagnetic torque decreases, and the motor power is insufficient, which is manifested as a decrease in speed. At the same time, the short circuit will cause unstable current, and the motor will produce abnormal electromagnetic noise during operation. In severe cases, it may also be accompanied by heating of the motor housing.
3. Blockage of Air Inlet/Outlet and Dust Accumulation on Rotor: When the fan is running, it needs to suck in air through the air inlet and discharge it from the air outlet after being accelerated by the fan blades. If not cleaned for a long time, dust, hair and other debris will block the air inlet and outlet, resulting in obstructed air circulation. The wind resistance during the rotation of the fan blades increases, which indirectly increases the operating load of the motor. At the same time, dust will also adhere to the motor rotor, the root of the fan blades and other parts, destroying the dynamic balance of the rotor, leading to intensified vibration during the rotation of the rotor, which will not only reduce the speed but also generate additional noise. In addition, excessive dust accumulation may also enter the motor, further aggravating the damage to the bearings and windings.
II. Solutions ciblées
1. Repair Bearing Lubrication or Replace Bearings: If it is judged to be a bearing problem (characterized by mechanical friction noise, and the fan blades do not rotate smoothly or have a stuck feeling when turned by hand), you can first try to supplement lubrication. For oil-impregnated bearing motors, you need to disconnect the power supply first, disassemble the fan housing, find the bearing end caps at both ends of the motor, and drop 2-3 drops of special motor lubricating oil (such as sewing machine oil, clock oil; avoid using edible oil). For ball bearing motors, you can disassemble the bearing seal ring and apply a small amount of grease. If the problem is still not solved after supplementing lubrication, it indicates that the bearing is severely worn, and the bearing of the same model needs to be replaced.
2. Overhaul or Replace Motor Windings: If the motor has obvious heating and electromagnetic noise (low “buzzing” sound), and the bearing problem is ruled out, the windings need to be inspected. A multimeter can be used to measure the winding resistance. If the resistance value is significantly lower than the normal range, it indicates a short circuit. Since winding maintenance requires professional winding and insulation treatment technology, it is recommended that ordinary users directly replace the motor of the same model to avoid potential safety hazards caused by self-repair.
3. Comprehensive Cleaning of Fan Dust: After disconnecting the power supply, disassemble the fan housing, and use tools such as a brush and a vacuum cleaner to clean the debris at the air inlet and outlet. Focus on cleaning the dust on the surface of the fan blades, the surface of the rotor, and the connection between the motor and the fan blades. After cleaning, gently turn the fan blades to ensure that they rotate smoothly without obstruction, and then reassemble the fan.
III. Preventive Measures
1. Regular Cleaning and Maintenance: It is recommended to fully clean the fan every 3-6 months. Especially in environments with more dust and hair (such as bedrooms, pet activity areas), the cleaning cycle needs to be shortened to avoid dust accumulation.
2. Regular Supplement of Lubrication: For oil-impregnated bearing motors, supplement special lubricating oil every 6-12 months; for ball bearing motors, check the grease status every year and supplement if necessary to ensure smooth operation of the bearings.
3. Standardize the Use Environment: Avoid placing the fan in a humid, high-temperature or dusty environment to prevent aging of the winding insulation layer and rust of the bearings; at the same time, avoid frequent starting and stopping of the fan to reduce the impact loss during motor startup.
4. Stable Power Supply Voltage: When using the fan, ensure that the power supply voltage is stable to avoid damage to the windings caused by excessive voltage fluctuations. If the voltage in the area is unstable, a voltage stabilizer can be used.
In summary, the core contradiction of “decreased speed + increased noise” of the fan is the increase in motor operating resistance and insufficient power output. Among them, bearing lubrication failure and dust accumulation are the most common incentives, which can be effectively prevented through regular cleaning and lubrication. If the problem stems from winding failure, the motor needs to be replaced in time to avoid the expansion of the failure and potential safety risks.
