1 In 2008, the output of air conditioners was 8,307.19 million units, second only to the United States and Japan, ranking third in the world. In this situation, China needs a large number of high-tech refrigeration and air-conditioning maintenance and repair personnel, many higher vocational colleges have opened this profession, and frequency conversion technology and inverter air conditioners are the key and difficult teaching content of refrigeration and air-conditioning disciplines. According to the characteristics of inverter air conditioner technology, the author developed a training device suitable for teaching.
2 program design
Under the premise of satisfying the teaching requirements, the project strives to be simple in equipment, small in one-time investment, long in use time, and to ensure the safety, reliability and operability of the device system, and to consider the technical optimization in the future, leaving a certain margin and position.
2. 1 appearance structure design
Taking into account the overall height characteristics of the students, the design follows the principle of ergonomics. The device is 1 m long, 0.77 m wide and 1.65 m high. The upper floor is the simulated room, the middle floor is the operation console, and the lower floor is the host platform. There are 4 universal wheels.
2. 2 functional design
The device presets the following features:
Cooling, heating, dehumidification, sleep, frequency conversion and other original machine functions; more than 20 fault setting functions, training students' hands-on ability and assessing students' judgment of fault handling ability: can directly reflect the frequency conversion compressor when changing the speed, the frequency , power, voltage, current, various pipeline temperature, high and low pressure, etc. to the change of parameters; to ensure safe and reliable in the process of use.
3 development functions
3. 1 refrigeration system development
The refrigeration system replaces the parts of the original machine with transparent plexiglass, which makes the system components clear at a glance and guarantees people's safety and device hygiene. The device system pipeline is moved to the back of the device accordingly, and a plurality of sight glass mirrors are installed in a position where the fault is easy to occur or the system is difficult to understand, and the gas-liquid change process of the refrigerant in the pipeline is visually seen.
And set multiple temperature detection points in the system pipeline, directly see the change of pipe temperature at different positions of the pipeline on the digital thermometer, use these parameters to analyze the working condition of the refrigerant in the system, and also can be used to analyze the cause and calculation of the fault. Other parameters. The switch of the stop valve is used to simulate the blockage of the refrigeration system, and the fault is set arbitrarily for the students to analyze and eliminate, so that the students can grasp the law of the fault. The indication after the pipeline transformation.
3. 2 electrical system development
The electrical system moves the indoor and outdoor control circuit boards to the faulty console, and then pulls out the operation panel for the frequent fault detection points to facilitate teaching. Let the students start from the perceptual knowledge of the electrical control components on the circuit, and then measure and analyze the working principle and law, then enter the overall circuit fault analysis, judgment and elimination, and master the comparison between the normal work and the abnormal work of the main board. Look for the understanding of the motherboard control.
3. 3 fault system development
On the premise of keeping the original machine working normally, according to the experience of maintenance, the fault and fault content are set in the place where the fault is likely to occur during use.
4 practical application test
The characteristic of the inverter air conditioner is that the greater the difference between the return air temperature and the set value, the faster the compressor turns, the larger the frequency, the larger the cooling capacity; conversely, the smaller. The prototype measured various parameters at different frequencies. It can reflect the changes of various parameters during the operation of the inverter air conditioner.
5 feedback effect after use
After the device is put into use, the feedback from students and teachers proves that there are advantages of four strengths, one high and one low, as follows:
(1) Intuitive. The overall structure is a stainless steel three-dimensional gantry. The indoor and outdoor machines are reasonably installed on the gantry. The plexiglass is used to replace some of the casings. It can directly see the parts and components of the various systems and the connection and orientation of the electrical components, making it easier for students to understand the system. principle.
(2) Strong mobility. The overall design of the device is beautiful, smart and free to move, which is convenient for teachers' theoretical teaching and experimental teaching.
(3) Strong teaching function. The device can provide refrigeration system, electrical control system component awareness, cooling, heating principle demonstration.
(4) Practical and operational. Set up human faults, which can easily and quickly set different faults, and apply skill training, fault diagnosis and assessment.
(5) The cost is low. In the market, this type of inverter air conditioner refrigeration and heating comprehensive experimental device is about 152 thousand yuan, and its own design only needs about 0.5 million yuan, saving 15,000 yuan for each school.
(6) High usage rate. In addition to being mainly used in the experimental training courses of refrigeration and air conditioning, the device is also suitable for professional learning such as building automation, turbine management, mechatronics, electrical automation, etc., to achieve a multi-purpose function.
6 conclusion
Through the device, the teacher conducts on-the-spot teaching to the students, so that the theoretical study will not be rigid and rigid, improve the students' interest in learning, and make the lectures handy; through the understanding and use of the device, students can develop their ability to use comprehensive knowledge and innovation ability; For different professional students, through the understanding of the device, in addition to the knowledge of the profession, you can also broaden your horizons, increase your knowledge, and break the situation that the professional division is too fine, resulting in a single situation in the school. High-quality technical talents to promote the reform of teaching models and teaching methods and curriculum construction.
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