1. Hot issues in household appliances
1.1 Alternative technical problems
In the early stage of development of the home appliance industry, most professionals advocated quality first. With the advent of the new era, many developed countries have changed their concepts, paid more attention to energy conservation and environmental protection, and advocated the sustainable development of the ecological environment. The replacement technology has been further developed. Most of the small household liquid humidifiers are R22. Most developed countries plan to reduce the use of R22. With the rapid development of science and technology, the currently relatively mature technology is R410 technology, which can effectively Instead of R22, it has a certain high pressure. With the continuous improvement of technology, the refrigeration system of the liquid humidifier itself can effectively withstand pressure. At present, some domestic enterprises in my country are gradually applying alternative technologies, but the related technologies still have certain limitations and cannot keep pace with the development of the times.
1.2 International certification of energy efficiency of home appliances
With the accelerating process of economic globalization, economic globalization has achieved unprecedented development. my country has continuously penetrated into the scope of the international market. After my country joined the WTO, my country's import and export trade volume has continued to increase. Energy efficiency puts forward higher requirements, not only to ensure the quality of products, but also to ensure energy conservation and environmental protection, in order to fundamentally improve the core competitiveness of my country's home appliance industry. Therefore, it is necessary to continuously strengthen the international certification technology of household appliances and unify testing standards and indicators in order to meet the needs of international development. Due to the different energy efficiency standards in various countries, there are many limitations in international trade. At present, due to different quality testing methods and different cultural backgrounds in various countries, there are large differences in the testing standards of the home appliance industry, which directly hinders international trade exchanges.
1.3 Frequency conversion technical problems
The frequency conversion technology in foreign developed countries has been very popular. Some large home appliance industries in my country have gradually introduced frequency conversion home appliances, which mainly include heaters and fans. Although frequency conversion products have been further developed in my country, my country still There is no unified technical standard, and most of the quality inspection standards can only refer to international standards. However, the types of most home appliances themselves are different, which will directly affect the experimental methods and inspection rules and cannot be adapted to frequency conversion home appliances. brought many difficulties.
2. About the main methods of quality inspection of household appliances
2.1 Detection of fixed resistors
Fixed resistance is an important part of household appliances. When testing it, two test leads must be connected to the pins at both ends of the resistance to measure the actual resistance value. In order to improve the measurement accuracy, it can be combined with Select the corresponding range for the size of the measured resistance. Due to the nonlinear relationship of the ohmic scale itself, the middle section of the scale is very fine. It is necessary to ensure that the indicated value falls to the middle position of the scale as much as possible, so as to ensure the measurement. accuracy. Combined with the different error levels of the resistance itself, a certain range of error is allowed. If it does not match and exceeds the error range, it means that the resistance value has changed. When testing, especially when measuring tens of ohms resistance, hands cannot touch the test leads and the conductive parts of the resistance. When testing, it must be welded to prevent other components of the circuit from affecting the test. affect the measurement error.
2.2 Detection of fuse resistors
In the whole circuit process, after the fuse resistor has a fuse circuit problem, it is necessary to combine practical experience to show that if it is found that the surface of the fuse resistor is blackened, it can be concluded that the load is too heavy. The main reason is that the current exceeds the rated value. many. If there are no traces of open circuit on the surface, the current flowing slightly exceeds its rated fusing value. It is impossible to judge the quality of the fuse resistor by the surface, and it is often measured by a multimeter, which can fundamentally ensure the accuracy of the measurement, so that the fuse resistor can be soldered on the circuit. If the resistance value is infinite, it means that the fuse resistor has failed. If the measured resistance value is similar to the nominal value, it means that the resistance has changed and is not suitable for the application. During maintenance, some resistors may also be broken down, which must be paid attention to when testing. During the maintenance process of the potentiometer, the rotary handle should be rotated in time to check whether it is balanced and the flexibility of the switch. If there is friction between the contact point inside the potentiometer and the resistor body, the quality is not good. .
2.3 Detection of Positive Temperature Coefficient Thermistor (PTC)
When testing, if you use a multimeter, you can often do the following operations. First, normal temperature detection, the two test pens are in contact with the PTC thermistor to measure the actual resistance value, and compare them. The difference between the two is about 2 ohms, which is normal. If the actual resistance value and the standard resistance If the difference between the values is relatively large, then there is a problem. Second, heating detection, based on normal temperature detection, timely heating detection, when it is close to the PTC thermistor for heating, it can be monitored by a multimeter whether its resistance value will increase with temperature, if it increases It means that the thermistor is normal. If there is no change, it means that there is a problem and cannot be used.
2.4 Detection of photoresistor
The detection method of the photoresistor is mainly to cover the light-transmitting window of the photoresistor with a black film, and then detect it by a multimeter. The pointer often remains unclear, indicating that the resistance value is close to infinity. If this finger is relatively small, it means that the photoresistor has been burnt through and damaged and cannot be used further. Aim the light source at the light-transmitting window of the photoresistor, the pointer of the multimeter will swing greatly, the resistance value will be smaller, and the performance of the photoresistor will be better. If the resistance value is infinite, it means that it is damaged inside and cannot be used any more. By shaking the small black piece of paper in the photoresistor shading window, it can receive light indefinitely, and the multimeter will keep swinging with the shaking of the black piece of paper, indicating that the resistance can be used. If the pointer of the multimeter does not shake, it means that the photosensitive material of the resistor has been damaged.