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Electric blanket solution
Electric blanket is a low-temperature heating product that relies on electric heating wire to generate heat. It is especially suitable for indoor humid and cold environments without heating equipment. Especially in winter, it is one of the necessary heating tools for every family. For the elderly, children, and people suffering from arthritis and asthma, using an electric heating blanket to sleep will achieve a very ideal physical therapy effect. The electric blanket is mainly composed of heating element, base core, fabric, power cord, junction box (connecting part of heating element and power cord), control switch (or thermostat), etc.
1. Classification of electric blankets
There are many brands of electric blankets on the market, and consumers must consider its safety, comfort, reliability, durability, and functionality when purchasing an electric blanket. There are two types of electric blankets commonly used in the market: single electric blankets and double electric blankets. The heating power used by a single person is mostly at 40～60W, and the heating power used by two people is mostly at 60 100W. According to different voltages used, there are electric blankets powered by 220V voltage and safety electric blankets below AC 24V.
(1) Ordinary electric blanket. It mainly relies on the plugging and unplugging of the power switch to realize power-on heating and power-off cooling, but it is inconvenient to control the temperature.
(2) Manual temperature control type. Most of the products on the market are of this kind. The switch is manually controlled. When the semiconductor diode is connected, the voltage is reduced to achieve the purpose of heat preservation.
(3) Automatic temperature control type. It adopts a constant temperature control device. When the temperature rises to a certain rated value (such as 40~6Oqc), it can automatically reduce the voltage or cut off the power, and it can automatically heat up when the temperature is too low. Constant temperature electric blankets are more high-end electric blankets.
(4) Safety electric blanket. There is a high-voltage type, which is directly connected to 22Ov AC; a low-voltage type, which usually reduces the voltage from 220 volts to tens of volts through a power transformer, and can be adjusted within a certain range.
(5) Multifunctional low-voltage health care electric blanket. This kind of electric blanket has the following advantages: firstly, it is safe, energy-saving and electricity-saving. The heating element adopts a new alloy heating wire with low resistance, high conductivity, high thermal efficiency and fast heating. The second is temperature adjustment and temperature control. The temperature adjustment switch adopts dual-circuit dual-temperature dual-control. The electric blanket on the same bed can be controlled in two different temperature zones according to different needs, so as to realize the regulation function of the temperature difference between two people. The temperature rise of the temperature control switch can be controlled within the range of 15-45°C, and has the functions of temperature adjustment, temperature control, keeping warm and removing cold to meet the needs of the human body.
(6) Electric blanket with magnetic therapy and health care function. The conversion of this kind of electric blanket from 220V to 24V low voltage is completed by magnetic field frequency conversion and step-down. The magnetic flux of some magnetic therapy or pulse health products is consistent, designed according to the composition of human body physiology, can regulate the acupuncture points of the whole body, loosen tendons and activate collaterals, promote the easy stretching of body joints, improve blood circulation, promote cell metabolism, and make endocrine vigorous.
2. The working principle of the electric blanket solution
The power supply of the electric blanket is directly connected with the heating wire through a switch and a fuse. During use, plug in the power plug, close the power switch, and the heating wire heats up, and the adjustment of its temperature can only be completed by the switch and plugging and unplugging the power plug. One of the fuses should play the role of overcurrent protection.
At present, electric blankets mainly use heating elements to work, and the main function of heating components is to convert electrical energy into heat energy. Now, the main heating element used in many electric blankets is the thermistor.
Thermistors are made using the property of semiconductor materials that the electrical resistivity changes with temperature. The commonly used semiconductor materials are iron, nickel, cobalt, molybdenum, titanium magnesium copper and other oxides or other oxides. Thermistors have the advantages of high sensitivity, larger temperature coefficient of resistance than metals, small size, small thermal inertia, good structure, strong mechanical properties, cheap price, and long life. But there are also poor reciprocity and complexity, severe nonlinearity, and narrow temperature measurement range.
3. Design safety plan of electric blanket
Electric blankets are mainly composed of heating wires, blanket materials, controllers, connectors and wires, and the heating wires, controllers and connectors play a key role in safety. In many spot checks by relevant national departments, it was found that all unqualified electric blankets mainly have the following problems. First, the heating wire of the electric blanket is unqualified for bending times, which is easy to break and cause ignition; second, the temperature control cannot be reached when folding. Standard requirements; Third, the leakage current index of live parts is unqualified. Safety electric blankets must have the following four elements:
1) The heating wire must use a pressure-resistant heating wire with a double-layer helical wire structure.
2) The controller must have anti-arc, anti-leakage and automatic protection functions.
3) The connector must have high compressive strength and airtight insulation connection function.
4) There must be a strict testing environment to ensure 100% safety.
1. Design of heating wire for electric blanket
The biggest safety hazard of electric blankets is fire. Therefore, it is necessary to consider how to prevent fire accidents caused by local high temperature of electric blankets, overheating of blankets, and sparks caused by broken wires. Compared with the ordinary single-layer heating wire, the double-layer spiral heating wire structure can detect the temperature signal and fault signal of the whole line due to the addition of the spiral detection wire layer, and quickly transmit these abnormal signals to the Controller for safety control.
2. Design of electric blanket controller
The controller is also commonly referred to as a switch. In the design of safety electric blankets, it can not only play the role of switching and temperature adjustment, but also need to cut off the power supply and protect the electric blanket safely. Therefore, compared with the ordinary two-core switch, the safety electric blanket must adopt a three-core structure. In addition to the power line, it is necessary to add an independent temperature and fault signal feedback channel, and use a high back-voltage rectifier and a high-precision temperature fuse. And current fuse device, etc., in order to realize the effective monitoring of the safety status of the electric blanket during use. Once an accident occurs, the power supply can be cut off in time to achieve multiple safety protections.
Through investigation, it is found that the burning of many electric blankets is not caused by excessive temperature, but caused by the arc spark of the controller. Therefore, the controller of the safety electric blanket must be able to prevent arc sparks. The controller of the electric blanket must use a flame-retardant PCB board and be equipped with a PA self-lubricating sliding contact. Hook welding, in order to effectively prevent arc sparks and prolong the service life of the switch.
3. Connector design
The connector is the device that connects the heating wire and the controller. Although this is a very important device, it is also a device that many electric blanket manufacturers ignore. Some manufacturers of inferior electric blankets directly use low-grade glue to connect the heating wire and the controller through wires, and some even use insulating tape to connect them. Electricity leakage hurts people. The connector of the safety electric blanket must have high compressive strength, and use flame-retardant PCB board and automatic constant temperature welding technology to ensure absolute safety between the heating wire and the controller. Ensure the insulation and airtight connection between the heating wire and the controller to eliminate potential safety hazards.
4. Design of electric blanket temperature control system
Electric blanket is a kind of low power consumption, economical and applicable heating equipment. At the same time, it also has the heating effect and economic effect that air conditioners cannot replace when sleeping. It is widely used among urban and rural residents in my country, especially in the vast rural areas in winter and spring. The phenomenon of heating is very common. However, ordinary household electric blankets only have two gears, high and low. When used in severe winter, the temperature of the high temperature gear is often too high, and the temperature of the low temperature gear is too low. Regulate, seriously affect people's sleep quality. This will not only make people feel uncomfortable, but also cause a waste of energy. Therefore, the research and development of new electric blankets and their control systems to improve the comfort, reliability and convenience of electric blankets has become the common expectation of users and electric blanket manufacturers, and it is also an important issue that needs to be solved in the development of the entire electric blanket industry.
The electric blanket temperature control system generally meets the following requirements: (1) The constant temperature control is stable. After the temperature is set, the temperature should be stable around the set value, and there should be no large fluctuations. (2) Strong applicability. There are many types of electric blankets, and the temperature control system should be suitable for different types of electric blankets. (3) Easy to operate. The adjustment of the temperature control system should be easy to operate and easy to master. (4) The structure is simple. The temperature control device should be simple in structure and easy to manufacture and install. (5) Good economic benefits. The temperature control system should save electricity as much as possible. (6) Good security. The temperature control system must have an upper limit temperature limit to prevent excessive temperature and prevent unsafe accidents.
At present, there are two kinds of commonly used electric blanket temperature control systems: temperature control systems based on thyristors, and intelligent detection and control systems. The principles of the two systems are different, and the working characteristics are also different.
The temperature control system based on the thyristor can manually adjust the potentiometer to adjust the heating power of the electric blanket, and its working mode is continuous heating, that is, the heating wire of the electric blanket is always working. The user can adjust the heating power to control the temperature of the electric blanket, which belongs to stepless temperature adjustment. However, due to the lack of an indicating device, the resistance value of the potentiometer can only be adjusted according to experience. The adjustment accuracy depends entirely on the user's experience. When the temperature adjustment is high, it may be An unsafe accident occurred.
Based on the temperature control system of the controller, the actual temperature is collected through the temperature sensor, and the current temperature of the electric blanket can be displayed in real time. The user can easily set the temperature. After reaching the set temperature, it will automatically stop heating. The working mode is intermittent heating. The method can effectively save energy under the premise of satisfying temperature control; and with corresponding protection measures, the safety is high.
5. Suggestions for purchasing electric blankets
In order to ensure the safety of electric blankets used at home and the service life of electric blankets, and to prevent and avoid unsafe factors in the process of using electric blankets, it is necessary to choose electric blankets correctly:
(1) When buying electric blankets, you must choose products that have passed the inspection of the national quality inspection department. Identify the safety sign (OS) of the electric blanket, indicating that it is a safe product that has passed the national quality and safety inspection. Do not buy the three-no products produced by small manufacturers, otherwise the safety of use cannot be guaranteed;
(2) To buy in regular shopping malls, the product must have the name of the factory, the factory logo and address, the date of manufacture, the inspector's seal and the certificate of conformity; there must be a clear and clear mark, which should reflect the specifications of the electric blanket, Manufacturer and necessary reminders;
(3) The area of the electric blanket is different, and the heating area is also different. Usually divided into single, double or triple electric blankets. Where possible, choose an electric blanket with a larger area;
(4) Choose fabrics with good quality as much as possible, and choose thicker ones than thin ones; the power should not exceed 6oW for a single person, and 120W for two people;
(5) Power-on inspection, put it in the high-temperature position, and touch the middle of the electric blanket with your hands for about 3-5 minutes. There should be a temperature rise, which proves that the position is intact. If the thermostat is of other types, the test time may be extended:
(6) The electric blanket power controller should be complete, smooth, free of defects, flexible to use, with clear switch marks, and the power cord used should be double-sheathed.
6. Matters needing attention in the use of electric blankets
(1) Before using the electric blanket, read the instruction manual carefully and operate in strict accordance with the instruction: (2) Do not insert pins; (3) Do not use when wet; (4) Do not dry clean or wash; (6) Do not allow people who cannot take care of themselves, infants, or people who are not sensitive to use; (7) Store in a dry place when not in use. Do not use folded; (8) Frequently inspect the appliance for signs of wear or damage, and if so, or if the appliance has been misused, return it to the supplier before next use; (9) If the power cord is damaged, in order to avoid danger, it must be replaced by the manufacturer or its maintenance department or similar professional personnel; (10) Using it at a high temperature setting position for a long time will cause skin burns.
The above are the details of the electric blanket solution introduced by Shenzhen Zuchuang Microelectronics Co., Ltd. for you. If you have electronic function development needs for electric blankets, you can rest assured to entrust them to us. We have rich experience in customized development of electronic products, and can evaluate the development cycle and IC price as soon as possible, and can also calculate PCBA quotations. We are a number of chip agents at home and abroad, including MCU, voice IC, Bluetooth IC and modules, wifi modules. Our development capabilities cover PCB design, single-chip microcomputer development, software custom development, APP custom development, WeChat official account development and other hardware and software design. It can also undertake the research and development of smart electronic products, household appliances scheme design, beauty equipment development, Internet of Things application development, smart home scheme design, TWS scheme development, Bluetooth audio development, children's toy scheme development, and electronic education product development.
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