With people's requirements for living comfort, the noise level of household air conditioner is becoming an important reference index for consumers when buy. As the power source of air conditioner, the compressor is the main source of noise, but the effective analytical method of noise vibration caused by motor was lacking. With the causes of the motor electromagnetic force was deduced, the motor electromagnetic force density was simulated and analyzed through the Maxwell. The effectiveness of the force density optimization was verified through the compressor noise spectrum, and then the correctness of the analysis method of vibration and noise was verified. And an effective simulation and calculation method was provided for the noise analysis and optimization of air conditioning compressor.

Because the domestic and foreign rice cooker markets mainly push the concepts of high-power heating and rice rolling, the heating power of rice cookers is increasing, the calorific value of internal components of rice cookers is getting higher, and the fan noise in the cooking process of rice cookers is getting bigger and bigger. Fan noise complaints have also become a hot complaint issue of rice cookers in the market. CFD fluid simulation technology is used to analyze the internal flow field of existing rice cookers, the fluid simulation calculation model and the experimental model are mutually verified, and a brand-new optimization design is carried out for the air intake grille structure and axial fan installation structure of the rice cooker. What’s more, the circular air intake grille and frameless fan design structure are adopted. The temperature rise and noise experiment of the whole machine proves that the optimization plan can reduce the noise of the whole machine of the rice cooker by 3 dB(A) and the temperature rise of electronic components does not deteriorate compared with the original model. This design of mute air duct system of rice cooker can play a certain guiding significance for the subsequent noise design of the whole fan of rice cooker and the improvement of temperature rise of core components.

For a abnormal noise problem in cross-flow air duct of a portable air conditioner. Based on the CFD numerical simulation and experimental method, the aerodynamic characteristics and the influence of abnormal noise of cross-flow duct are analyzed. The abnormal nosie problem of the portable air conditioner is caused by the air flow in the gap between two sides of the blades and the chassis, which interferes the main flow and increases turbulence noise, resulting in the abnormal noise and unstable wind speed. The problem of abnormal noise is eliminated by modifing the design of air duct curve, which controlled the distribution of eccentric vortex and the entrainment area of eccentric vortex is offset upward, which increases the flow area of the cross-flow fan. It provides a solution for the abnormal sound of the subsequent cross-flow air duct. It provides a solution for the abnormal noise of the cross-flow air duct.

The primary source of noise of a hermatic reciprocating compressor is the acoustic radiation from its housing. The acoustic radiation pressure of sheets is related to the vibration velocity amplitude, normal to the surface. To control such surface normal velocity, optimization of parameters such as plate thickness, plate stiffness and the reinforcement structure by ribs can be adopted. VTF (Vibration Transfer Function) simulation and analysis of the compressor housing is carried out to locate the spot with largest vibration on both upper and lower shells. An topological optimization of the compressor housing is conducted based on OptiStruct, and the optimal position, shape and size of the stiffener are derived, which can be referred to as the stiffener design guidance. According to modal and VTF simulation results of the optimized shell structure, the 1st-order and 2nd-order natural frequency increase by 8.5% and 3.0%, respectively. Meanwhile, the maximum normal vibration velocity of the response points on the shell decreases by 23.6%, lower than the target value. Through experimental verification of vibration and near-field acoustic pressure, the results show that vibration acceleration has reduced by 21.5% at the peak of 72 Hz, and the near-field acoustic pressure has dropped in the frequency bands below 2500 Hz and above 10000 Hz. The effectiveness of the morphological optimization simulation in improving the housing stiffness and reducing radiative noise based on OptiStruct has been verified.

In order to study the noise fluctuation of 800~1000 Hz during the operation of refrigerator, study the factors affecting the effect of suction muffler of refrigerator compressor. Firstly, analyze the influence of heating rate on muffler noise reduction effect. Then, the acoustic characteristics of different suction port structure and sealing of muffler are studied by using Virtual.Lab software, and the transmission loss curve is calculated. The results show that the noise of compressor and refrigerator can be reduced at the same time by improving the sealing of the muffled chamber. In the stable operation stage of the refrigerator, the average noise near 800 Hz is reduced from 31.1 dB(A) to 28.7 dB(A), with an average reduction of 2.4 dB(A), and the standard deviation is reduced from 3.87 to 1.49. The stability of the refrigerator noise is significantly improved, which provides a feasible direction for the optimization of the sound quality of the refrigerator.

Abnormal sound detection is an important part of compressor quality control. Aiming at the characteristics of rare compressor fault sample signals, a method is proposed to extract the common characteristics of normal signal samples of refrigerator compressors by using self-encoder to realize fault detection. On the basis of a large number of normal signal samples, common features are extracted. Due to the different reconstruction errors of normal and faulty samples, the optimal threshold can be determined as the fault classification standard. The research results show that: under the condition that the fault signal samples are sparse, the common characteristics of the normal signal samples of the refrigerator compressor are used to detect the fault signal samples, and the judgment accuracy rate can reach 97.4%.

Ice maker is a common functional part of the premium refrigerator product, it can meet the needs of users in ice making at home. However, the excessive noise from the ice block flow channel is a common problem during ice making, seriously affects the user’s sense of hearing. It aims at the noise problem from the flow channel in ice maker, conducts dynamics simulation studies on the process of ice blocks fall in the original and improved flow channels of different shapes with the help of simulation software, improves the structure of original flow channel, proposes the noise reduction improvement method. Last, makes samples of the flow channels and verifies their practical noise reduction effects, provides the engineering guidance for solving the similar noise problem.

The research on the anti failure technology of small refrigeration compressor valve plate mainly focuses on the motion law, structural design, fault diagnosis, material selection and treatment. Through investigation and summary on these aspects, it is found that all research directions have certain common conclusions, and there are certain deficiencies. Researchers in this field can further carry out innovative research on the anti failure and reliability technology of valve discs based on the contents of this review.

As a new type of physical heating technology, radio frequency heating technology is characterized by fast heating speed, deep penetration depth and selective heating. And it has a strong development and application potential in the traditional food industry or household kitchen appliances. This article summarized the research and application of radio frequency heating technology in food thawing and food cooking. The effects of radio frequency heating on the efficiency and uniformity, food nutrition and health quality and edible quality during food thawing and cooking were described in this article. In addition, the existing problems and improvement measures were analysed, the future research directions were prospected, to provide theoretical guidelines for research and application in kitchen appliances.

Leakage current detection has always been one of the key issues of electric water heater controller and electric water heater manufacturer. Aiming at the problem of high false alarm rate and false alarm rate in the current built-in leakage current detection of electric water heater, based on the original built-in leakage current detection circuit, the DC bias circuit is added to improve the anti-interference ability of the circuit, and the leakage current alarm value adjustment circuit is added to calibrate the deviation of the alarm value of leakage current and improve the detection accuracy. Based on the above scheme, a new built-in leakage current detection circuit is built, and experimental research and demonstration are carried out on the controller of electric water heater. The experimental results show that the application of this circuit can improve the anti-interference ability and detection accuracy of built-in leakage current detection, so as to greatly reduce the missed alarm rate and false alarm rate of built-in leakage current detection of electric water heater.

System integration is an effective method and path to rapidly develop intelligent emerging household appliances, the system integration analysis of the intelligent clothing care machine is carried out by using "comparison method""decomposition method""modularization" and other methods, the overall structure of the intelligent clothing care machine is determined, including function performance, safety modeling man-machine coordination and other aspects; Systematically analyzes the core function “wrinkle removal” of smart clothing care machine, finds out five different technical methods on the key factors of wrinkle removal, and tests and verifies two of them, which provides a reference for the development of smart clothing care machine.

The filter of heat pump clothes dryer is easy to get dirty, which has a significant impact on the drying time and drying energy consumption. The self-cleaning of the filter has become an important research direction of 10 kg heat pump dryer. Centrifugal separation technology is applied to the self-cleaning filter of heat pump clothes dryer. The basic performance of the prototype and self-cleaning prototype such as air volume and noise was tested. The results show that: the no-load circulating air volume and operation noise of the self-cleaning machine are close to the original machine. In terms of drying performance under half-load condition, the average drying time of the original machine is 116.3 min, and the drying energy consumption is 1.452 kW•h, the moisture content is -1.47%. And the average drying time of the self-cleaning machine is 116.0 min, and the drying energy consumption is 1.461 kW•h, the moisture content is -1.40%. Under the condition of unclean the filter, the original machine began to dry impervious in the fourth drying cycle. The main reason is that the accumulation of wire chips on the filter, and this leads to the increase of wind resistance, and the no-load circulating air volume is greatly reduced from 311 m³/h to 251 m³/h. During the 100 cycle reliability test of the self-cleaning machine, the drying performance showed a relatively stable fluctuation trend. The average drying time of 100 cycles is 117.6 min, the average drying energy consumption is 1.478 kW•h, and the average moisture content is -1.50%. The drying time, drying energy consumption, moisture content, no-load circulating air volume and operating noise of the self-cleaning machine after 100 cycles is basically consistent with the self-cleaning machine before long-term operation and the original machine. The centrifugal self-cleaning clothes dryer is stable and reliable. Finally, analyzed the performance of the original machine and self-cleaning machine by simulating the actual use scenarios. After 10 years, the total drying time of the self-cleaning machine is reduced by 943 h, the total energy consumption is reduced by 511 kW•h, the carbon emission of the self-cleaning machine is lower.

To better control the swing amplitude of the fan blade driven by large deformation, a blade control method was presented to reduce the deformation and simultaneously meet the aerodynamic performance, with the combination of Fluid-Solid Interaction simulation and high-speed three-dimensional imaging. Firstly, the main working area was analyzed through the fluid simulation. Then, the camber of the blade root was redesigned, which improved the local stiffness to reduce the whole deformation without seriously affecting the performance. Finally, the maximum swing of new structure decreased from 1.388 mm to 1.074 mm, with a decrease of 22%. The aerodynamic performance test result verifies the reliability of the proposed control method and the improvement of sound quality.

Defrosting system is the basic system to ensure the normal operation of the refrigeration system of frost free refrigerator. If the defrosting system fails, the refrigerator cannot cool normally. The design of defrosting fuse is the key link in the safety design of air-cooled refrigerator. The height of the evaporator of the single system pair door frost free refrigerator is about twice that of the ordinary air-cooled refrigerator, and the heat transfer distance is increased, so it is difficult to achieve reliable defrosting effect. From the market after-sales maintenance situation, the phenomenon of abnormal fusing of defrosting fuse in frost free refrigerator products is common in the industry. In order to solve the problem of defrosting system, several main fault causes of fuse abnormal fusing are determined through investigation and test analysis. The reliability method of fuse design: bidirectional balance method is proposed. That is, balance the two tests of residual test and dry and wet burning test to find the best design position. Ensure that the fuse of the refrigerator will not fuse abnormally under various environments. It provides an important reference method for design practitioners in the industry.

According to the requirements of simulated leakage test in Appendix FF (normative appendix) of GB 4706.32-2012 standard, a set of refrigerant leakage simulation test device is designed.. The device is developed based on the flammable refrigerant R32, mainly composed of precision electronic scales, gas analyzers, proportional control valves, pressure gauges, computers and other components. Through automatic control, the device can release refrigerant at a constant speed and quantitatively, read data such as the concentration and weight of the refrigerant in real time, improve the test accuracy, the accuracy and consistency of test results are improved, and it has high promotion value.

Based on the principle of binocular parallax, the principle of binocular visual ranging is studied and analyzed, the binocular ranging system is designed and the binocular ranging system platform is built. Zhang Zhengyou camera calibration method is used to determine the camera in the system with a single target to obtain the actual focal length and distortion coefficient of the camera. Further, the system itself is determined with a double target to obtain the relative position relationship between the two cameras. Based on the calibration results, the distortion of the collected image is corrected to obtain a more accurate image. Then, it is proposed to carry out surf feature matching for the corresponding images collected by the left and right cameras through the combination of RANSAC method and epipolar constraint method. Finally, the relative position relationship between the experimental object and the ranging system is obtained. The experimental results show that the measurement accuracy of the designed ranging system meets the requirements in the effective measurement range, and the measurement accuracy of the central position area is the highest in the effective measurement area.

The experimental platform of air source heat pump direct floor radiant heating system is built, and its heating effect, operation energy efficiency and thermal storage effect are experimentally studied. The results show that the heating effect of the new system is good, and the indoor temperature can be stable at about 20℃ when the ambient temperature is above -10℃. When the outdoor temperature is 10℃, the system COP is 4.25, and when the outdoor temperature is -10℃, the COP can reach 3.65. At the same time, the thermal storage effect of the floor radiant heating system is good. The outdoor temperature is 0℃, and the indoor temperature can still be maintained above 12℃ within 120 min after shutdown.

In view of the user's demand for the functions of clothing freshness, deodorization and rapid wrinkle removal, the renewal iteration of washing technology of washing machine is constantly upgraded, and steam washing technology came into being. Studies the effect of steam washing technology on the washing performance of different materials (cotton, viscose, polyester, polyester/cotton blend). The results show that the steam washing process has little effect on the wear resistance of all kinds of fabrics under the mode of wear, ironing and storage. The steam washing mode has excellent deodorization effect on the four fabrics. In addition, the wrinkle removal effect of fabrics is different at different speeds during steam washing, and the wrinkle grade difference is greater than 2.5. The effect of rotational speed on cotton fabric wrinkle removal is not obvious. Low rotational speed is conducive to polyester fabric wrinkle removal, while high rotational speed is conducive to viscose and polyester cotton fabric wrinkle removal.

The vibration problem of cylinder washing machine has always been the focus of product improvement, and the suspension system is a common vibration reduction measure of cylinder washing machine. Taking the suspension system of cylinder washing machine as the research object, firstly, the virtual prototype model of suspension system is established by ADAMS, and the simulation results of virtual prototype are verified and analyzed. The amplitude is basically consistent with the experimental results at the stable speed stage, which shows the effectiveness of the simulation model. Then, based on Box-Benhnken’s central composite experimental design principle, the orthogonal experimental table is designed. Through variance analysis, it is determined that the stiffness coefficient of spring, damping coefficient of damper, mass of upper counterweight and mass of lower counterweight have significant influence on the amplitude of suspension system. Finally, multiple regression analysis and response surface method are used to optimize the optimal structure parameter combination. The optimized suspension system amplitude decreases by 14.8%, which shows the effectiveness of this optimization method.

Expanded polypropylene (EPP) material has good compressive strength mechanical properties and excellent toughness, which could be recycled in the packaging of home appliances. The microscopic cell morphology, tensile strength, compressive strength of EPP and expanded polystyrene (EPS) were compared by scanning electron microscope, electronic universal testing machine, zero drop testing machine, frequency conversion simulation vibration table and inclined plane impact testing machine, permanent compressive strength, and cyclic use simulation test, the results show that the tensile strength of EPP material is better than EPS under the same density, the compressive strength is close to that of EPS material, and the durability of parts is more than 5 times that of EPS. The excellent protective effect of EPP material product packaging has been widely used in the home appliance packaging industry.

The water pumping system of portable air conditioner can effectively utilize the cooling capacity of the condensate and improve the removal of condensate. In order to optimize the utilization of condensed water, studies the influence of the water pumping system on the generation and utilization of condensed water, as well as the impact on the performance of the whole machine, and then study the impact of condenser flow paths on the utilization of condensed water. The results show that: under the condition of 85%~97% relative humidity, the water pumping system can evaporate 74.69%~93.57% of condensed water, and the theoretical analysis of adiabatic humidification shows that portable air conditioner under this working condition has the potential to evaporate all the condensed water. The comparative study of the condenser flow paths shows that ensuring that the high-temperature side of the condenser is fully in contact with the condensate, which can further improve the condensate removal capacity. After optimization, the rated cooling capacity is increased by 1.31%, the energy efficiency (EER) is increased by 2.42%, and the continuous operation time without overflow under the condition of 95% relative humidity is extended from 0.4 hours to 5.5 hours. In addition, the comparative study of the condenser flow paths shows that the design of the portable air conditioner condenser needs to comprehensively consider air convection heat transfer and condensate evaporative heat transfer. On the premise that the performance meets the requirements, increasing the proportion of condensed water evaporative heat transfer can improve the condensed water removal capacity.