Key Manufacturing Technologies for Premium Efficiency Electric Motors
The most important thing for premium efficiency electric motors is the degree of production process assurance. The process of continuously improving the efficiency of electric motors is a process of continuous product upgrading, and it is also a symbol of the comprehensive level of a national motor industry.
The main point of premium efficiency motor design is to reduce various losses and improve motor efficiency. The measures taken include: applying special off-line tools to increase the stator slot full rate and increasing the cross-sectional area of the copper wire; improving the manufacturing accuracy, shortening the length of the coil ends, strengthening the manufacturing quality of the punched pieces and the stator core, thereby reducing iron consumption And excitation current and the copper loss caused by it; improve the rotor slot insulation process and reduce load miscellaneous consumption; rationally select the grade of silicon steel sheet to reduce iron loss and stator copper loss.
Influencing factors of motor efficiency
Motor losses include stator and rotor copper losses, iron losses, mechanical losses, and stray losses. There are many ways to reduce motor losses and improve efficiency:
The measures to reduce the copper loss of the stator mainly include reducing the stator resistance and shortening the winding end length; thinning the insulation, improving the slot full rate, increasing the cross-sectional area of the conductor, and using new materials to reduce the resistivity of the electromagnetic wire;
The measures to reduce the aluminum consumption of the rotor mainly include the use of a large cross-sectional rotor groove shape and an increase in the end ring cross-section, improving the purity of aluminum, and reducing the rotor resistance, etc .;
The measures to reduce iron loss mainly include the use of low-quality high-quality cold-rolled silicon steel sheets to reduce the eddy current loss of the motor; adjusting the groove shape and selecting a reasonable magnetic flux density to reduce the fundamental iron loss; increasing the core length and reducing the magnetic flux density to reduce the loss ; Improve the quality of iron core manufacturing and ensure the insulation of silicon steel sheet surface;
Measures to reduce mechanical consumption mainly include high-efficiency fan structure and reasonable air path, increase blade surface roughness, make the air flow smooth, improve fan efficiency, and reduce wind friction; choose high-quality low-friction bearings, grease, reduce friction loss; improve the shape Position tolerance accuracy to ensure the quality of the motor assembly, reduce friction loss, etc .;
Measures to reduce stray losses include the use of multiple slots in the stator slots, reducing the width of the stator and rotor slots, non-magnetic material at both ends of the core, and the use of "sinusoidal" windings to weaken higher harmonics in the magnetic field and weaken additional losses. , Properly increase the air gap, the rotor uses fewer slots, using magnetic slot wedges, precise control of the degree of skew, the use of special measures such as skew.
2. Key manufacturing technologies to reduce motor losses
2.1 Technical Measures to Reduce Mechanical Consumption
Intermediate tolerances of parts and components are used to improve the accuracy of form and position tolerances to ensure that parts are not deformed during transportation and assembly, and at the same time to ensure the quality of the motor assembly, thereby reducing friction losses. Production experience shows that the use of the bearing chamber rolling technology can effectively improve the machining accuracy of the bearing chamber's mating parts and reduce a series of problems caused by the bearing's running accuracy; the use of online quantitative lubrication technology of the bearing grease can stably control the grease injection The number of people ensures the stable mechanical consumption of high-efficiency motors for mass production.
Rolling bearings are commonly used for bearings of small and medium-sized motors, and suitable high-quality lubricants are used. The traditional process is to manually apply grease to the bearing before assembling the bearing, then assemble the bearing, and finally refill the motor with a grease gun. The problems with this method of manual grease filling are as follows: the amount of application is not easy to control, which affects the lubrication of the bearing parts and mechanical loss; the grease is easily contaminated, and there is oil stain around the motor parts after manual application; Inconvenient operation.
There is currently no device capable of quantitatively filling the motor with oil. In order to effectively control the amount of grease added, after a large number of technical verifications, it was determined to apply automatic grease injection machines, oil pipes, quick-change joints, etc. to achieve automatic quantitative oil injection of the motor on-line assembly. This technology sets the oil filling machine at the lower line of the motor assembly line. The motor does not need to be filled with grease during the assembly process. When the motor is offline, the quick-change joint of the automatic quantitative oiling device of the assembly line is connected to the motor oil filling pipe, and the oil filling machine can be started. Grease the motor automatically. This device has the advantages of convenient use, accurate quantification, high efficiency and quickness, and is currently widely used in high-efficiency motors and other motors, and has obtained national utility model patents.
2.2 Technical measures to reduce stray losses
The rotor outer circle is widely used in motor manufacturers for turning. Due to the influence of the notch aluminum strip, turning alternately from hard silicon steel sheet to soft aluminum. Due to the poor accuracy of the machine tool, the size of the rotor after machining the outer circle is unstable. For example, the use of a one-turn tool and a small machining allowance for some of the outer diameter of the rotor will result in poor surface quality of the outer diameter of the rotor, large burrs, or serious adhesion between the rotor surface pieces, resulting in large motor consumption, high temperature, and low efficiency. Therefore, it is particularly important to standardize the machining process, parameters, and quality inspection standards of the rotor outer turning.
The magnetic field commutation frequency of the rotor is very low, and the hysteresis loss and eddy current loss generated by the rotor silicon steel sheet itself can be ignored. The miscellaneous loss mainly comes from the lateral current loss caused by the conduction of the aluminum guide bar at the slot and the outer circle of the rotor punch. Need special finishing, roasting, and special treatment of the outer circle to increase the resistance between the rotor's outer circular guide bar and the punch, punch and punch, and reduce stray losses caused by lateral current. Through analysis, new tools and processes can be promoted and applied when the rotor is finished.
Most manufacturers use 450 positive deflection cutters for the outer circle of car rotors. The blade inclination angle is a positive value. Under the same cutting parameters, the axial component force of the cutter is large, which makes the silicon steel sheet rewind and stick. The new process uses a 930 positive partial Sandvik machine clamping knife. Because the axial component force of the tool is small, it can reduce the rewinding and adhesion of silicon steel sheets, and can effectively improve the surface processing quality of the rotor.