Study On Noise Reduction Of DC Motor Used In Air Valve Regulation In Automotive

In order to improve the driving comfort of the car,now all the cars are equipped with air conditioner.The motor is the driving part of climate control actuator of the air conditioner.With The method of adjusting the opening of flap of air-conditioning in vehicle by micro DC motor is to output a certain speed and torque to drive lever by actuator gear system.The motor noise could make driver not comfortable.The improvement of motor noise follows the Six Sigma DMAIC model to improve and reduce motor noise.The task of this study is to,according to the specific requirements of customers,reduce motor noise level 2d BA under the condition of no change on motor outline dimension and electrical performance.Regarding evaluation of noise measurement system,the "analysis of variance theory with repeated experiment interaction" is used to deduce and calculate the repeatability and reproducibility of the noise measurement system.At the same time,the advantages and disadvantages of various measurement system evaluation methods are compared.The advantage of measurement system variance analysis method is that it can distinguish the variance of the measured parts,the variance of the measured person,the variance of the interaction between the parts and the measured person,and the variance of the measurement system.It can effectively evaluate the repeatability and reproducibility of the measurement system.In the analysis phrase,the factors that affect the motor noise are listed:static magnetic torque,armature resonance,armature unbalance,friction vibration between commutator and brush leaf,clearance between bushing and shaft,lubrication between locating spacer and bushing surface;at the same time,a viscoelastic material(super glue x)is applied between brush leaf and plastic end cover to restrain the vibration of brush leaf.Based on positive balancing production process and commutator polishing technology,the controllable are determined for further experiment.In the improvement phrase,through the screen DOE and the analysis of variance and main effect of test data,it is determined that the two factors influencing noise are armature balance and commutator roughness,and there is no interaction between armature balance and commutator finish and other three factors(clearance between bushing and shaft,super glue x,spacer and bushing surface grease).Through full factor experiment design and response regression analysis,the fitting model is found and verified that is quadratic nonlinear model.Through the design of optimization tools,we find out the suitable control range and tolerance of armature balance and commutator finish.According to the tolerance range of armature balance and commutator finish,the process capability is confirmed to meet the requirements through trial production.For coming mass production control,control parameters and specifications are added into the control plan to ensure the strict implementation of this measure.