The crankshaft balance block of reciprocating compressor is to deal with the dynamic balance of the compressor core during operation. When the compressor stops, the movement is in unbalanced state. Due to the existence of the inertia of the movement at the moment of shutdown, the movement will remain in the original state of motion. The reaction force of the refrigeration system to the core is easy to cause the core to shake at the moment of shutdown and generate noise. By studying the vibration noise at the moment of compressor stop. Several schemes to reduce the instantaneous impact energy of the machine core during shutdown are put forward and compared with the experiments. According to different application conditions, the optimal control scheme of compressor shutdown is given to reduce the vibration and noise fluctuation at the moment of shutdown.

With the popularization of parallel flow evaporator in household air conditioning, the research on sound quality has been carried out gradually, when the wind direction of the parallel flow evaporator is not parallel to the blower, the abnormal fin noise sound is more likely to occur, in order to improve the abnormal fin sound of parallel flow evaporator of household cabinet machine, a 9-point weighted average noise subjective evaluation method is proposed, combined with CFD simulation and experimental test, the influence of the size and swing angle of the built-in air deflector on the subjective evaluation of abnormal fin sound and the performance of the air duct was investigated, 300×70mm air deflector with 30°swing is selected as the optimal scheme. Under the condition of satisfying the performance index of air duct, the sound perception of the fins of the cabinet is improved obviously.

When the refrigerator compressor run at 3900 rpm, the radiation noise ranged from 1500~3000Hz is loud. The noise easily cause the user to get upset. To reduce the radiation noise, the sound absorbtion cotton is pasted on the cover plate of the compressor cabin, but the sound absorbtion effect is limited, only 0.7 dB(A). To solve this problem, a composite sound absorption structure with micro perforated plate and sound absorption cavity is proposed. To design the sound absorption cavity, the numerical simulation is adopted to calculate the sound absorption coefficient of sound absorption cavity with three sizes, and the size is determined to be 20 mm. After experimental verification, the compressor radiation noise is reduced by 1.74 dB(A) at 3900 rpm, which indicates the composite sound absorption structure is effective to reduce noise.

The electromagnetic noise mechanism and vibration noise control of microwave oven with magnetic leakage transformer are studied. By analyzing the mechanism and transmission path of microwave noise, the noise reduction methods with targeted and efficient are designed to control the vibration and noise of microwave oven. The transmission path of electromagnetic noise caused by transformer is described and evaluated the contribution of each path noise to the whole machine in detail. And, the reasonable analysis method and noise reduction means are applied to reduce the vibration and noise level of the microwave oven.

Through the theoretical analysis on the mechanisms of refrigerator drawer impact noise. We analyze the method of reducing collision noise according to the energy conservation law and the following procedures are used, i.e. , reduction into the spring elastic coefficient and self-locking stroke to reduce the initial elastic potential energy, the increaseof the equivalent friction coefficient of slide to improve friction dissipation, and change of the material property of the gasket to increase the damping dissipation. The experimental results show that the three measures have good optimization effect. The experimental results confirm the conclusion of theoretical analysis, and provide a credible design basis for the development and improvement of the impact noise of refrigerator.

For the problem of the compressor exhaust pipe resonance, select one of our refrigerators, and model the simulation of the refrigerator exhaust pipe in two ways according to the design drawings: pipeline modeling and high-resolution scanning equipment scanning modeling that get its natural frequency distribution characteristics. Analysis based on experimental and simulated fixed frequency results, we found there is a large error between the simulation results and the experimental tests, with a maximum error rate of 14.9%. Using high-precision scanning equipment for physical scanning modeling, the simulation results obtained are closer to the experimental tests. The maximum error rate is 6.8%, which effectively reflects the solid-frequency distribution characteristics of the actual exhaust pipe, reduces the error impact caused by the conventional method of modeling and simulation according to the diagram, and studies the refrigerator pipeline modeling and simulation. Optimized design provides reliability reference.

The running noise of the wall mounted integral heat pump water heater is large, about 49 dB(A) before the improvement. The main noise sources are compressor and fan running noise, piping vibration, and so on. The wall mounted integral heat pump water heater is installed usually in the toilet, and the running noise affects people's daily life. Through the improvement of the compressor anti-vibration pad and fixing method, fan speed and blade twist angle, piping vibration reduction and noise propagation path etc., the noise of the machine can be reduced by about 10 dB(A), and the noise reduction effect is obvious.

Noise is one of the main performance indexes of refrigerator, which users pay more attention to. Therefore, it is important to carry out effective noise matching design of refrigerator, solve the problem of abnormal noise, and conduct research on test process and methods. Through combing the development process and the coupled operating conditions of refrigerator noise source, a set of test program was developed and integrated into the control module. The integrated noise test method can realize the research of compressor vibration noise with changing frequency, fan and compressor speed matching design, optimization and verification of key noise issues, etc. This can improve efficiency of product development, also provide design guidance for subsequent products, which is beneficial to reduce refrigerator noise.

Air-cooled refrigerators have developed rapidly in recent years, and the related research has become a hot spot. Based on energy saving, this paper analyzes the integrated design of refrigerator and compressor, the type of air-cooled condenser and its cooling air bias phenomenon, the condenser and compressor in series heat dissipation, cabinet embedded condenser heat dissipation design and so on.

In order to promote the localization process of power modules for inverter controllers for home appliances, fill in a gap that is a lack of detection methods for inverter controller. This paper proposes a detection method, which is a method for detecting IPM in terms of performance, reliability, capability, appearance quality, external dimensions, electrical properties, dielectric strength, electrostatic discharge, electromagnetic compatibility, mechanical strength, restricted substances. In addition, the intelligent power modules also need to be tested in terms of solder delamination, package defects, and environmental durability. Furthermore, test methods and judgment basis are given for each test content, etc.

When design household intelligent washing machine, the accuracy of water level detection in washing machine barrel is very important. The accuracy of water level is directly reflected in the washing ratio, energy efficiency, user experience and so on. Traditional water level sensors are two-wire or three-wire, and the detection accuracy can only reach about 10% due to the influence of line length, temperature and anti-interference performance, which leads to a large error in judging the height of water level in the washing machine, which is not conducive to the intelligent control of the washing machine. Introduces an integrated digital pressure sensor for water level detection, which can greatly improve the accuracy of water level detection, effectively ensure the water level error within a controllable range, and ensure the energy efficiency, washing ratio and user experience of the washing machine.

The connecting pipe is the main component that connecting the outdoor unit and the indoor unit, make the freezing medium forms a closed cycle in the whole air-conditioning system. At present, most of the materials used in the connection pipes are copper pipes. Due to the special material properties, the connection pipes are prone to scratch and deformation on surface during the connection process, which leads to leakage. Through simulation experiments, it is found that the maximum stress position is where the bell mouth contacts the boss under the thread of the pipe joint, and the other is where the bell mouth contacts the bottom of the pipe joint. Increasing the thickness of the position to improve the sealing properties. With the applying of the finite element analysis software, analysis the mechanics property of different structures of the bellmouthing, confirming the optimized double-layer bellmouthing structure and increasing the tightening torque allows the connecting pipe to fully squeeze and mesh to improve the sealing performance of the connecting pipe.

Simulation analysis of the drag force of the drawer structure and the maximum stress of the buckle in the pull-out process. The pull-out force of the drawer structure and the stress concentration position of the buckle in the actual situation are predicted. In order to improve the accuracy as much as possible, the model is not simplified. The simulation results are tested to compare the difference between simulation results and experimental values. The experimental method is to measure the drag force with a tension meter. According to the feedback of the test results, it can be concluded that the simulation results are close to the experimental values. This indicates that the simulation method can be used as a design method.

The choice of household appliances with sterilization function has a positive protective effect on the health of consumers, especially during the epidemic period. In order to find out whether the healthy household appliances have the function of epidemic prevention, the relevant product standards of sterilization function of household appliances issued by the national household appliances standards committee were studied. On the basis of the experimental research, using the comparative method, the sterilization technology of household appliances and the biological inactivation of virus and bacteria were analyzed in depth, and the standard of bacterial inactivation of sterilization appliances was compared with that of coronavirus. Through the comparison, we found that the current household appliances such as clothes dryers, dishwashers, washing machines, disinfection cabinets and air purifiers can have epidemic functions. Finally, it provides the basis for consumers to choose anti epidemic appliances to avoid the influence of consumers' wrong choice on their own health.

By investigatihg and discoverihg the key issues in the construction of the recycling system for Waste Electrical and Electronic Equipment in Beijing, by investigating the recycling and disposal industry of Waste Electrical and Electronic Equipment in Beijing and the green recycling pilot work of the “Energy-saving Products into Supermarkets” activity in Beijing. The role of the “one machine, one code” traceability system for Waste Electrical and Electronic Equipment, and actively building a coordinated development model of the whole industrial chain of green recycling in Beijing are countermeasures to solve the development problems of the recycling industry. Finally, putting forward policy recommendations in order to promote the coordinated development model of the completely industrial chain of green recycling in Beijing.

Referring to Verman's three-dimensional framework theory of standard system and the basic framework of standard system for household electrical appliances, this paper puts forward the idea of constructing a three-dimensional reference model of standard system for household electrical appliances and the principle of compiling standard system table, to guide the application of new technology, promote the development of industry technology and optimize the organizational management.

The abnormality of the resistance of the post-slice chip resistor is analyzed. The abnormality of chip resistors is due to the sulfuration phenomena at the chip resistor pad, which is confirmed by scanning electron microscopy and energy spectrum analysis. The sulfuration mechanism of chip resistors is studied, and several measures of the prevention from resistors sulfuration are provided.

Sponge cake was seen as the research object in this study. On the basis of single factor experiments, the response surface method Box-Behnken center combination principle was used to optimized the processing technology of the sponge cake. Regression model was established to investigate the effect of baking time, baking temperature and steam on cake texture, color, sensory score and acrylamide content. The results showed that the process of sponge cake was optimized as follows: baking temperature of 167℃, baking time for 25min, steam period for 17%. The actual sensory score of sponge cake was 82, the brightness is 52.11, and the acrylamide content is 0.0302mg/kg with this condition.