At present, the electric heating water heater sold on the market is deeply loved by the people because of its convenient installation and use.
However, due to the lack of standardization in the design and construction of many building power sources in China, the safety of electric water heaters in the use process is particularly important in real life.
According to the requirements of relevant standards in our country, leakage-proof control parts are installed in the electric heater water heater when it leaves the factory. However, accidents continue to occur due to improper operation or leakage prevention failure. So how can we make the economical and environmental water heater absolutely safe, so that we can use it safely? For this reason, the author designed and manufactured the human body induction automatic power-off safety controller of household electric water heater, thermostatic element which can achieve safety and reliability in anti-electric shock. The principle is: after the infrared radiation of human body is received by the infrared receiving window of the human body induction automatic power-off safety controller, the infrared thermal signal of human body is converted into the control circuit of Schmidt trigger controller composed of electric signal triggering IC555 by infrared component, which promotes the action of two groups of four-contact relays, and automatically disconnects the power supply of the electric water heater to make it work. The electric heating water heater is completely isolated from 220V AC during its use, thus ensuring the absolute safety of the user in the aspect of anti-electric shock during the use. The test results show that when the user does not enter the use area, the two groups of four contacts are always connected to supply the normal heating power for the water heater. When the user enters the use area, the infrared component of the controller receives the infrared radiation from the user’s human body, thus providing the signal for the subsequent IC555 trigger circuit and making the controller work propelled. When the relay operates, the normally closed contacts of the relay are completely disconnected to achieve the purpose of safe use.
When the user leaves the use site, because the infrared component can not receive the infrared thermal signal, the subsequent controller loses the control signal, and the relay can not get power. When the delay is over, the relay closes again because of the malfunction of the closed contact and continues to supply power to the water heater. The infrared receiving module is mainly composed of optical Fresnel lens system, pyroelectric infrared sensor, signal filtering and amplification, signal processing and control circuit. The Fresnel lens of the infrared module of the human body radiates the infrared radiation through the electric water heater in the course of using.
Its special structure also generates alternating infrared radiation intensity and intensity signals to adapt to the changing characteristics of the signal required by the pyroelectric detector. The core of the controller design is pyroelectric infrared transmission. Sensor devices convert infrared signals of human body into electrical signals for signal processing. Signal processing mainly amplifies, filters, delays and compares the weak electrical signals output by sensors, which lays a foundation for the realization of automatic control functions. In order to make it easy to use the market-ready infrared probe components, the control part of IC555 is manufactured by ourselves. The characteristic of the human body induction automatic power-off safety controller is that it can respond to the infrared radiation change caused by the user moving in the use area, generate and promote the control circuit with IC3555 as the core to trigger the relay action, so as to achieve the function of controlling the water heater to automatically turn on and automatically turn off, thus realizing the safe use of the water heater.
Grounding end: Grounding end (GROUND). Fig. 1 is the physical picture of the infrared receiving sensor, Fig. 2 is the internal structure diagram of the infrared receiving sensor, Fig. 3 is the finished infrared probe assembly on the market, Fig.
4 is the transformation and shaping diagram of the Schmidt trigger and waveform formed by IC555, and Fig. 5 is the controller circuit diagram made by myself. In the control process of the human body induction automatic power-off safety controller of household electric water heater, two feet of 555 circuit are used as triggers at the input end.
Fig.
4 shows typical Schmidt triggers and waveform transformations and shaping figures of IC555 as shown in Fig. 4 (a) and Fig. 5 Application examples. It is the core part of the automatic control of the controller. Fig. 5 is the practical application of IC555 typical Schmidt trigger in this case. The detection part of the controller should be 2.
0-2.2 meters from the ground.
Should be far away from air-conditioning, refrigerators, stoves and other sensitive to changes in air and temperature. No other isolators shall be found within the scope of detection. The control system of human body induction automatic power-off safety controller for household electric water heater based on infrared sensor and IC555 has the advantages of simple structure, easy operation, convenient use and low cost.
It can realize the full automatic control of electric water heater in its normal work.
After many tests and the practical application of my family, the system works stably and reliably, and has good popularization and application value.