The precision of the new energy vehicle motor shaft is one of the core factors affecting vehicle performance. Its processing precision and assembly precision are directly related to the stability of motor operation, energy conversion efficiency and the power performance of the whole vehicle. From the basic principle of mechanical transmission, as a key component for transmitting torque, the new energy vehicle motor shaft needs to be precisely matched with bearings, gears, couplings and other components. If the dimensional accuracy, shape and position tolerance or surface roughness of the shaft exceeds the design allowable range, it will trigger a series of chain reactions, which will have a multi-dimensional impact on the vehicle's power, economy and reliability.
The diameter, length and other dimensional parameters of the new energy vehicle motor shaft must be strictly matched with the matching parts. For example, if there is a deviation in the matching tolerance between the shaft and the inner ring of the bearing, it may cause excessive clearance or insufficient interference after assembly. When the clearance is too large, the bearing is prone to radial runout during operation, increasing mechanical vibration and noise. At the same time, the loose fit causes torque transmission loss, so that the power output of the motor cannot be effectively transmitted to the wheels, resulting in slow acceleration and weakened climbing ability of the vehicle. Insufficient interference may cause relative sliding between the inner ring of the bearing and the shaft, generate friction heat, aggravate component wear, and even cause bearing ablation in severe cases, resulting in power interruption and affecting driving safety.
The shape and position tolerances of the new energy vehicle motor shaft, such as roundness, cylindricity, and coaxiality, are key indicators to ensure the rotation accuracy of the shaft system. If there is a roundness error in the journal, the inner ring of the bearing will be unevenly stressed, resulting in periodic alternating loads, accelerating the wear of the bearing balls or raceways, and causing unbalanced vibration of the motor rotor. When the coaxiality error is too large, the axis of the new energy vehicle motor shaft and the reducer input shaft deviates, resulting in poor gear meshing and eccentric load, which not only increases transmission noise, but also aggravates gear wear due to local stress concentration, reduces the service life of the transmission system, and even causes serious faults such as gear breakage. These abnormal vibrations and noises may also be transmitted to the vehicle through the chassis, affecting driving comfort.
The surface roughness of the new energy vehicle motor shaft directly affects its friction state with the contact parts. If the shaft surface is rough and there are many peaks and valleys at the microscopic level, the actual contact area will be reduced, the pressure per unit area will increase, and the lubricating oil film will be difficult to form, thereby aggravating friction and wear. Under high-speed rotation conditions, this friction will generate a lot of heat, which will increase the temperature of the motor, accelerate the aging of the winding insulation, and even cause the motor overheating protection to start, limit the output power, and affect the vehicle's cruising range and power performance. In addition, the rough surface may also become the attachment point of the corrosive medium, accelerate the rust of the shaft surface, and further damage the matching accuracy.
The accuracy of the new energy vehicle motor shaft not only involves the mechanical level, but also affects the electromagnetic performance by affecting the position accuracy of the rotor. For example, the straightness error of the shaft will cause the air gap between the rotor and the stator to be uneven during rotation, the magnetic resistance of the area with a large air gap will increase, and the area with a small air gap may have local magnetic saturation, which will cause the motor no-load current to increase, the power factor to decrease, and the efficiency to decrease. This deterioration of electromagnetic performance will reduce the output torque of the motor at the same input power, while increasing energy loss, resulting in an increase in the vehicle's power consumption and a shortened cruising range, especially under high-speed driving or frequent start-stop conditions, the impact is more significant.
During the assembly process of new energy vehicle motor shaft and other components, if the positioning reference is inaccurate or the assembly process is improper, the dynamic characteristics of the entire shaft system may change. For example, insufficient assembly accuracy of the coupling will cause additional bending moment in the shaft system during rotation. When the excitation frequency is close to the natural frequency of the shaft system, resonance may occur. Resonance will cause the vibration amplitude of the motor and transmission system to increase sharply, which will not only aggravate the fatigue damage of the components, but also may interfere with the electronic control system, battery components, etc. of the vehicle, affect the stability and reliability of the vehicle, and even cause safety hazards in extreme cases.
In the context of increasingly fierce competition in the new energy vehicle industry, high-precision processing and assembly of new energy vehicle motor shaft has become an important manifestation of the company's technical strength. By adopting advanced processing technology (such as CNC grinding machine precision grinding, ultra-precision turning, etc.) and high-precision testing equipment (such as three-coordinate measuring machine, roundness tester, etc.), strictly controlling the dimensional accuracy, form and position tolerance and surface quality of the shaft, the operating efficiency and reliability of the motor can be effectively improved, thereby improving the vehicle's power response speed, cruising range and NVH (noise, vibration and harshness) performance. For example, a new energy vehicle company has improved the motor efficiency by 2% and the vehicle's cruising range by 15-20 kilometers by optimizing the processing accuracy of the new energy vehicle motor shaft. At the same time, the noise inside the car has been reduced by 3-5 decibels, which has significantly improved the market competitiveness of the product.
As new energy vehicles develop towards high power density, high speed and long life, the accuracy requirements of new energy vehicle motor shafts will continue to increase. For example, the application of new technologies such as flat wire motors and oil-cooled motors requires the shaft system to maintain stable operation at higher speeds (such as more than 20,000 rpm), which poses more stringent challenges to the dynamic balance accuracy and thermal deformation control of the shaft. At the same time, the popularization of integrated electric drive systems has made the integration of new energy vehicle motor shafts with reducers, differentials and other components higher, and the cumulative error control of assembly accuracy has become the key. In the future, by introducing intelligent processing equipment, online detection technology and digital assembly technology, the full-process precise control of the accuracy of new energy vehicle motor shafts will become an important development direction for the manufacturing of core components of new energy vehicles, providing stronger technical support for improving the performance of the entire vehicle.
