Bearing wear has a profound impact on wall fan motor, which is mainly reflected in the reduction of mechanical efficiency, reduced operating stability, increased noise and increased safety hazards. First of all, the direct impact of bearing wear on mechanical efficiency is particularly significant. When the clearance between the inner ring of the bearing and the shaft exceeds 0.1mm, the contact stress distribution between the rolling element and the raceway will be significantly distorted. This change causes the friction coefficient to rise from the initial value of 0.0015 to above 0.003. The abnormal increase in friction causes the input power of the motor to increase by 15% to 20% under the same load. At the same time, the effective output torque decreases by 8% to 12%.
In terms of operating stability, the vibration problem caused by bearing wear cannot be ignored. When the wear reaches 0.2mm, the first-order critical speed of the rotor system will shift down by 15%, which will cause the motor to produce a radial runout of ±3mm at the rated speed. This vibration not only destroys the dynamic balance of the fan blades and forms periodic airflow pulsation, but may also be transmitted to the mounting structure through the base, causing cracking of wall decoration materials. Laboratory test results show that when the vibration acceleration exceeds 0.5g, the loosening rate of the internal fasteners of the motor increases by 40%, while the reliability of the electrical connection decreases by 30%. Therefore, vibration control is an important part of ensuring the normal operation of the equipment.
In terms of noise control, bearing wear is also a serious problem. The metal debris generated by wear will form abrasive particles in the lubricating oil. These hard particles with a diameter of 10-50μm circulate in the bearing cavity, resulting in intensified collisions between the rolling element and the cage. When the particle diameter exceeds 30μm, the impact energy is sufficient to excite the natural frequency of the bearing ring and generate a broadband noise of 200-500Hz. This noise not only increases the sound pressure level by 8-12dB, but also forms a sharp metal friction sound, which seriously affects the user experience.
In terms of safety protection, temperature anomalies caused by bearing wear are also worthy of attention. The friction heat generated by wear can cause the bearing temperature to rise by more than 40K. When the temperature reaches 120℃, the viscosity of the grease base oil decreases by 70%, and the lubricating film thickness is reduced from 3μm to 0.8μm. This lubrication failure will further aggravate the wear, forming a vicious cycle. Even more dangerous is that high temperature will cause the bearing steel to undergo a phase change, and its hardness will drop from HRC62 to below HRC45, thus reducing the load capacity by 50%. When the wear reaches 0.3mm, the bearing clearance almost disappears, and the risk of bore scraping between the rotor and stator increases by 300%.
