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Hair dryer solution
Hair dryers are mainly used for drying and shaping hair, but they can also be used for local drying, heating and physical therapy in laboratories, physiotherapy rooms, industrial production, and art.
1. The principle of the hair dryer
1. The working principle of the hair dryer
Hair dryers are mainly used for drying hair and shaping, and can also be used for drying food and clothing. When the hair dryer is powered on, the motor drives the fan blades to rotate, sucking air from the air inlet, heating it through the electric heating element, and blowing the hot air out from the air outlet, coupled with appropriate switch settings and temperature control protection, output different temperatures and Air flow at different speeds.
2. Types of hair dryers
Hair dryers are divided into three categories according to their usage: professional, home and travel hair dryers. Among them, professional hair dryers generally use AC motors to drive the fan blades, which have large power, sufficient air volume, and long service life; household hair dryers generally use DC motors, and the power is relatively small; travel hair dryers are small in shape, can be folded and stored, and are easy to carry It is small and mostly adopts dual voltage design, which is convenient for travel.
3. Structural accessories of hair dryer
The main parts of the hair dryer include power cord, switch, air inlet net, anti-skid rubber, wire protection sleeve, combination of motor and fan blades, heating wire frame, air outlet net, and heat insulation tube. Common accessories include diffusers and nozzles.
2. Design method of hair dryer scheme
1. Hair dryer design ideas
First, according to the customer's requirements, design the shape that meets the customer's requirements; then design the internal structure that meets the requirements according to the shape, including the motor and fan blade combination, heating wire frame; design the circuit diagram and heating wire layout, and select parts; design samples Carry out the test, send it to the certification body for testing, and start production after passing the certification test. The focus of the design is the shape and the heating wire frame part.
2. Design principles of hair dryer
Appearance design principles: The appearance of the hair dryer should consider ergonomic factors. The handle must be suitable for one-handed operation of all functions. It is light in weight and convenient for the operator to use with one hand for a long time. It must be stable, not flipped, not moved when tabletop.
The basic design scheme of the shape: the hair dryer can be divided into two schemes: the front/rear shell and the left/right shell according to the design scheme of the outer shell. Tightening, the advantage is that it is not easy to break when it is dropped, but the shape will be limited by the direction of the mold release. The front/rear shell interface is the position of the largest diameter size: the shell of the second scheme cooperates with the buckle to tighten In addition to solidity, metal buckles or cylinders are generally added to the front end to assist in fixing. The advantage is that the shape is changeable, but the shell is easy to break. These two solutions have their own advantages and disadvantages, and they can be flexibly adopted according to the needs of customers. As long as they can meet the needs of customers and strengthen the design in weak links, they can design qualified products.
The main criteria for parts design:
①The size of the outlet and inlet mesh must meet the test requirements in the safety standard. In the case where the distance from the electrified body cannot meet the requirements of safety standards, plastic materials must be used.
②The switch can be designed at any position on the handle, and the principle is that fingers can operate when holding the product with one hand. The cold air switch is designed on the upper part of the handle so that it can be pressed by the index finger. The pressure regulating switch is designed at the lower part of the handle, which cannot be twisted or pushed by fingers alone, and must only be operated under the condition of using a special tool.
③Anti-slip rubber is designed on both sides of the hair dryer, using soft and elastic plastic materials, such as PVC.
④The protective wire is set at the end of the handle. Pay attention to the hardness of the material, especially when used with the power cord, it should meet the tortuous test required by the safety standard. The principle is "thin is hard, thick is soft". Generally use PVC material.
⑤The combination of motor and fan blade directly affects wind speed, air flow, noise, product life, etc. The main material of the motor frame and fan blades is PC, which has the characteristics of relatively stable size and good mechanical strength. The fan blades of the silent series hair dryer should be made of PP material, which is light in weight, so that the load on the motor is small. The speed of the motor is generally 15000-20000rpm, and the life of the motor is difficult to guarantee when the speed is too high. When designing a DC motor hair dryer, if there is a cooling function, a 24-28 volt motor should be considered, because a high-voltage motor requires relatively less current, and the air outlet temperature can be lower in the cooling gear. Except for special customer requirements, when the life of the DC motor of the hair dryer is ≥200 d~, the life of the AC motor is ≥500 hours. The ideal motor is: high speed, high efficiency, low spark, low noise.
⑥ Commonly used heating wires for hair dryers include iron-chromium resistance wire and nickel-chromium resistance wire. Iron-chromium resistance wire has the characteristics of high resistivity, small temperature coefficient of resistance, and high operating temperature, but it is easy to oxidize. Nickel-chromium resistance wire has higher resistivity, good surface oxidation resistance, and higher strength at higher temperatures , has good processability and weldability, and relatively high cost. The shape of the heating wire is mainly wavy and spiral. Among them, the helical wire can use a harder heating wire, while the wavy wire must use a softer wire, otherwise the wire will break during winding. The wavy wire is beautiful but the processing cost is high. .
⑦ In addition to being used as the insulation and heat insulation part of the front part of the hair dryer and the heating wire frame, the heat insulation cylinder is also used to correct the air turbulence caused by the shape of the hair dryer.
⑧When designing accessories, the area of the air outlet should be considered as not less than that of the hair dryer, otherwise the temperature of the accessories will rise and deform after prolonged use.
⑨Select the power cord with the corresponding certification mark and meet the safety standards of the country of sale. The plug must have the certification mark of the country of sale and meet the maximum current of the hair dryer.
3. Matters needing attention in the design and development of hair dryers
1. Regulations on electrical safety distance
The distance between all live parts of the hair dryer (such as heating wires, rivets, copper wires, etc.) and the air outlet net must be at least 8mm. However, if the opening of the air outlet net is larger than 3mm, the distance is required to be 15mm. In addition to the product requirements, there should be no other openings on the fuselage, and the parts with openings must meet the corresponding test finger and test needle test requirements of the safety standard. If the safe distance between the coincidence part of the product shell and all the live parts in the fuselage is not enough, it must be separated by supplementary insulation. The distance between the charged body and the charged body inside the product is usually designed with a distance of 100V/lm m. In actual design, it is generally designed with a minimum distance of 3mm. Depending on the size of the space, a distance of >3mm can be designed. The minimum climbing distance and clearance distance meet the specific requirements of the national safety standards for sales.
2. Requirements for switches and circuit boards
The switch used in the hair dryer should have the corresponding certification mark, and the rated current and voltage of the switch must be greater than the rated current and voltage of the hair dryer. In the design of the circuit board, the distance between the IJ N poles is 3.2mm. Others must be designed according to 100V/lm m. The switch of the hair dryer has many gears, which can cause high and low wind speed and power. In order to achieve this effect during design, one or more diodes are generally used in series on the line to cause half-wave conduction of the current to reduce the power and the speed of the micro-motor. However, when designing products with European and Chinese specifications, attention should be paid to the harmonic test of EMC in safety standards. In the design circuit, the current through each diode should not exceed 3A. If the current exceeds the standard, it can be neutralized by using two diodes to reversely control different heating wires.
3. Selection of electronic components
The thermostat is the main component of the safety protection of the hair dryer, and a thermostat with a certificate should be selected. The selected temperature of the thermostat cannot be set too low to prevent the problem of automatic triggering of the thermostat when the machine is shut down. Generally, the commonly used temperature of the thermostat is 90°C to 140°C. The thermal fuse is the last barrier for the safety protection of the hair dryer. Generally, a thermal fuse supported by relevant certification certificates is used. Its main performance is that the maximum passing current meets the requirements and the rated temperature control temperature requirements are stable. The selection temperature of the thermal fuse is generally about 30~C higher than that of the thermostat to prevent the problem that the thermal fuse is disconnected earlier than the thermostat is triggered. The EMC pressing parts in the hair dryer are composed of safety capacitors connected to the positive and negative poles of the power supply, ceramic capacitors welded to the micro-motor, monolithic capacitors, electrolytic capacitors and inductors. Different parts have different effects on EMC interference, for example The low frequency part of EMV needs to adjust the capacitance value of the capacitor, and the high frequency part needs to adjust the inductance value of the inductor. As for the harmonic (HARMONIC) part, the line design needs to be changed. The above parts should be adjusted according to the test situation of the designed product.
4. Technological requirements for the design of heating wire frame
The stamped copper rivets at the terminals need to be added with gaskets in a "sandwich" manner. Except for components with obvious planes such as thermostat feet and lead connectors, copper gaskets must be added to other components when connecting to ensure that the connection points in the circuit are secure. Sufficient contact area to prevent fusing elements. The size of the bent leg of the thermal fuse must be larger than its minimum size, otherwise the thermal fuse will be damaged. The wiring terminals and intermediate tap terminals at both ends of the wave heating wire must be clamped to prevent poor contact. After the heating wire is wound, the spacing between the heating wires is required to be uniform, and there is no phenomenon of touching wires, twisting, less waves or multiple waves; all exposed copper wires cannot collide with each other, cannot touch other electrical components, and cannot reduce the safety distance; the heating wires have no obvious damage. The distance between the output lead of the negative ion generator and the air outlet meets the requirements of safety regulations, and the distance from other charged objects should not be less than 32mm.
4.The safe use of electricity in the use of hair dryers
Hair dryers are high-power household appliances (power can reach 1000 watts), and there is a certain risk of leakage, because the environment in which they are used is humid or there is a high chance of significant water, so standard power sockets should be used. It is necessary to pull out the plug of the hair dryer after use. On the one hand, there will be a certain amount of power consumption if the plug is not pulled out. On the other hand, it is easy to burn out the electrical appliances when the voltage is unstable. When pulling out the socket head, you should pinch the plug to pull it out. This is to prevent the plug from being damaged when the wire is pulled, and to prevent the risk of accidental electric shock due to uneven force.
If the power cord or plug is damaged or becomes hot during use of the hair dryer, stop using it immediately. This is firstly because the line damage will lead to the risk of leakage and increase the possibility of electric shock; secondly, the line voltage may be unstable, if the voltage is too high, the current will increase and cause the line to heat up, which may damage the electrical appliances; Avoid continuous use of the hair dryer for a long time.
The moment the hair dryer is turned on and used, an electric spark will be generated. Electric sparks are a normal physical phenomenon, but electric sparks can easily cause fires and cause personal and property losses. Special attention should be paid to the safety of electricity use in places where some dangerous goods exist. Otherwise, it is easy to increase the possibility of disaster.
Although the hair dryer is a civilian electrical appliance, its rated voltage is very harmful to the human body. If there is any damage, it should be sent to the designated professional maintenance place for repair or replacement in time. This is because on the one hand, in order to avoid unnecessary injuries to customers, on the other hand, it is also to protect the service life of the hair dryer. Unprofessional dismantling or maintenance will easily cause damage to the internal structure of the hair dryer, thereby reducing the life of the hair dryer. service life, there is also the risk of direct damage to the hair dryer.
5.The electromagnetic radiation of the hair dryer
We know that for all kinds of household appliances, electromagnetic radiation problems will exist.
First, let me talk about some basic knowledge: as long as the voltage is connected to both ends of the electrical appliance, there must be an electric field; as long as there is current flowing in the electrical appliance, there must be a magnetic field around the current; and the voltage and current in the electrical appliance are often A changing, changing electric field creates a magnetic field, and a changing magnetic field creates an electric field. Therefore, regardless of the size of household appliances, whether they are hair dryers, rice cookers, electric washing machines, compressed household refrigerators, air conditioners, fully automatic washing machines, or computers, TVs, microwave ovens and other household appliances, as long as they are related to electricity, When used, it will more or less radiate an electromagnetic field outward.
As one of the electrical appliances, the hair dryer is no exception. Every time you enjoy the gentle warm air after washing your hair, you may not have thought that this small appliance actually consumes a lot of power per second. The power can reach 1000 watts, even higher than that of a refrigerator. Work power for such a behemoth. Compared with a mobile phone that relies on a small battery to work at the milliwatt level, or a microwave oven with the door tightly closed to shield radiation during work, when a high-power electrical appliance such as a hair dryer is working, the radiated electromagnetic field strength exceeds these "Radiation key suspects" is not surprising. However, the electromagnetic field radiated by the hair dryer is stronger, which does not mean that it is more harmful to human health.
First of all, we compare the electromagnetic radiation of household appliances with X-rays: X-rays are an ionizing radiation, while the electromagnetic fields radiated by household appliances are non-ionizing radiation. X-ray radiation is similar to nuclear radiation, which can cause the molecular bonds of cells in the human body to break, and has the possibility of causing cancer. It must not be underestimated, and dose control is very important during application. Non-ionizing radiation does not have this ability.
Besides, although the radiation emitted by electrical appliances is non-ionizing radiation, and most of them belong to the radio wave band in electromagnetic waves, the electromagnetic fields radiated by different electrical appliances have different frequencies if they are different. For hair dryers, AC current with a frequency of 50 Hz is used, and correspondingly, the frequency of electromagnetic waves generated around the hair dryer is also around 50 Hz. The frequency of electromagnetic waves emitted by mobile phones for communication is in the range of 0.8GHz to 2GHz. The microwave in the microwave oven is also roughly at this frequency, and the operating frequency of the circuit in the computer CPU is several GHz, and the frequency of the radiated electromagnetic field is also roughly in this range. As far as the numerical value of the frequency is concerned, it can be seen that the radiation frequency value of the hair dryer is much lower than that of other home appliances. The difference in frequency makes the mechanism of their influence on the human body different. After the radio frequency electromagnetic field is absorbed by the human body, it will be converted into the energy of the fast-moving molecules in the body. Friction occurs between the fast-moving molecules and the temperature rises. Microwave ovens use this thermal effect to heat food. The energy of the electromagnetic field is relatively large (such as the strength of the electromagnetic field inside the microwave oven), which is enough to pose a real threat to the human body. The low-frequency electromagnetic field (that is, like a hair dryer) will not have the heating effect of the radio frequency electromagnetic field.
The possible threats to human health mainly lie in the fact that low-frequency electric fields and low-frequency magnetic fields can generate or induce currents in the human body. If the currents are large enough, they can stimulate nerves and muscles. However, to produce this kind of stimulation, the energy of the electromagnetic field itself must be large enough to sum up. Although the working power of the hair dryer is relatively large, it can indeed radiate a certain electromagnetic field. However, because the radiation of the hair dryer is a low-frequency electromagnetic field, it is far below the intensity that will harm the human body. Therefore, as long as we use the hair dryer correctly, the radiation from the hair dryer will not cause damage to our health.
6. Common faults and maintenance of hair dryers
1. The motor does not turn: this kind of failure is the most common. When overhauling, first check whether the heating wires EH1 (warm wind heating wire) and EH2 can burn red (you can observe from the air outlet, and pay attention to set the power switch to the "hot air" position). If the EHI cannot burn red, the fault is generally in the power plug, power cord, power switch or corresponding power line. As long as you measure them one by one with a multimeter, you can quickly find out where the fault is. Usually, the power cord is desoldered, broken and the power switch is damaged. If EH1 can be burned red, it means that the 220V power supply has entered the hair dryer normally, and the fault is generally in the motor power supply circuit or the motor and its fan blades. In this regard, you can first use a screwdriver to extend the back of the hair dryer into the manhole, and gently move the fan blades. If it can be pulled out, it means that the fault is in the motor itself or in the power supply circuit. Unscrew the screw on the handle, disassemble the hair dryer and measure whether there is working voltage at both ends of the motor (generally, the voltage of the permanent magnet motor of the hair dryer is 10-18V, or check whether EHI and DI-D4 are normal), and if it can be ruled out after this inspection If the power supply circuit of the motor is faulty, it means that the motor itself is bad. For the inspection method, please refer to the following item 4. Motor power supply circuit faults mostly occur near the joints at both ends of the EHI. After reconnecting, pay attention to tighten the compression screws at the joints. If the fan blade cannot be moved or is jammed, it indicates that the fault is on the fan blade and other parts, mainly caused by the change of the position of the fan blade or the deformation of the fan blade. After readjusting the position of the fan blade (motor) or correcting the shape of the fan blade, the Troubleshootable.
2. No hot air: The motor rotates but no hot air is sent out, which is caused by the lack of heat of the EH2. When overhauling, mainly check whether the connector leads at both ends of the EH2 are broken, desoldered or poorly connected. Because EH2 is connected with lead wires with soldering tabs and compression screws, loosening and short cracks are more likely to occur. Tighten the compression screw after reconnecting the broken end. In a few cases, EHI broken wire failure will also occur, and the broken end can be sanded and then twisted and connected.
3. No cool wind: The hot air shield is normal but there is no cool wind. The fault is in the power switch, which is usually caused by the deformation of the switch reed or severe oxidation and singeing of the contacts. Carefully disassemble the power switch, correct the shape of the reed with tweezers or use sandpaper to remove the oxidized dirt on the relevant contacts to troubleshoot.
4. The motor is flying and the noise is very loud: this kind of fault is caused by a bad motor. and cannot be restarted. During maintenance, after disassembling the hair dryer, it can be seen that the carbon brush or commutator of the motor is seriously worn and stained with more dirt. In this regard, first wipe off the carbon powder and other dirt with absolute alcohol or carbon tetraoxide, and then properly smooth the head of the carbon brush to keep it in good contact with the commutator without too much pressure. If the spring is loose, the carbon powder pressure will be small, and poor contact will easily occur, so the spring can be properly lengthened. If the carbon brushes are excessively worn, replacement with new ones should be considered.
5. Insufficient air volume: Generally, it is caused by too low motor speed. If there is no problem with the carbon brush pressure and resistance of the motor according to the above method, the fault is usually caused by severe wear of the motor bearing or lack of oil. You can replace the bearing, motor or add lubricating oil .
6. The wind temperature is low or sometimes high and sometimes low: it is mainly caused by poor contact of EH2. The resistance value of the EH2 of the 450-600W hair dryer at room temperature should be 100-120 ohms. If the measured value is greater than this value, the fault can be confirmed. Poor contact generally occurs at the contact at both ends of EH2.
The above are the details of the hair dryer solution introduced by Shenzhen Zuchuang Microelectronics Co., Ltd. for you. If you have electronic function development needs for hair dryers, 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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