Fall-off detection method and system of exhaust sensor of variable frequency air conditioner

Abstract

The invention discloses a fall-off detection method and system of an exhaust sensor of a variable frequency air conditioner. The fall-off detection method comprises the steps that when the air conditioner starts or switches a running mode, the running mode is judged, and if the running mode is a heating mode or a refrigeration mode or a dehumidification mode, timing is conducted according to firstrunning time, and the exhaust temperature and the outdoor environment temperature are collected in real time; when the time reaches the first running time, whether temperature rise of the exhaust temperature is larger than a preset value A or not, whether the difference between the exhaust temperature and the outdoor environment temperature is larger than a preset value B or not, and whether thedifference between the exhaust temperature and the target exhaust temperature is smaller than a preset value C or not are judged, if all the judgments are yes, it is shown that the exhaust sensor doesnot fall off, and the method is terminated; otherwise, it is judged that the exhaust sensor has fallen off, an electronic expansion valve is controlled to be opened to an appropriate extent, and a worker is reminded that the exhaust sensor falls off. By means of the fall-off detection method, whether the state of the exhaust sensor is normal or not can be accurately judged, and false alarm can beeffectively prevented.

Description

technical field [0001] The invention belongs to the technical field of air conditioners, and in particular relates to a method and system for detecting the drop-off of an exhaust sensor of an inverter air conditioner. Background technique [0002] At present, due to cost considerations for frequency conversion compressors in the air-conditioning industry, compressor manufacturers have successively canceled the overhead temperature control protectors that come with the original compressors. The purpose of the original compressor top-mounted temperature control protector is to ensure that the temperature of the compressor body is controlled within the national standard E-class insulation limit of 115°C. The controller will be automatically disconnected, and the compressor will be shut down for protection. When the exhaust temperature drops to the reset temperature of the thermostat, it will automatically reset and start the compressor. As an air conditioner manufacturer, due ...

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Problems solved by technology

The reason why this method is used for fixing is different from the fixing method of the temperature sensor of the coil temperature sensor in the middle of the inner and outer heat exchangers. The O-shaped sensor bracket is used, and the O-shaped sensor fixing bracket is welded to the copper tube, and the sensor is fixed. The temperature-sensing probe is directly inserted into the O-shaped bracket to make the reliability higher; because the temperature-sensing probe of the exhaust sensor should not be too far away from the exhaust port, it needs to be controlled within the range of 100-150mm; The vibration will be too large in the near position, and the vibration stress is relatively concentrated. If brazing is performed at the position of the copper tube in this range, it is easy to produce welding metallographic fission, which will destroy the strength of the copper tube and cause a refrigerant leakage accident.

The method of fixing the U-shaped bracket on the copper pipe also has a certain risk of falling off. With the long-term vibration of the compressor, the U-shaped bracket is made of galvanized material. Under the high-temperature radiation of the compressor exhaust and long-term vibration, the rigidity It will also decrease year by year, and the locking force will become weaker. If the compressor is operated in a range where the vibration frequency is relatively high, there is a risk that the temperature sensor of the compressor exhaust sensor will fall off from the fixed position. Every year, after-sales maintenance in the air-conditioning market will expose many exhaust sensors. Fault case where the temperature sensor falls off

At present, the temperature sensor fault detection in the industry only stays in the short circuit or open circuit of the sensor lead, and it is still impossible to judge that the sensor temperature probe has fallen off from the detection position; if the exhaust sensor temperature probe falls off from the fixed position, the control system cannot detect the real temperature of the exhaust gas , the detected temperature can only be slightly different from the ambient temperature, but the discharge temperature of the compressor itself has indeed changed greatly, and at this time the control system will make an error based on the detected real temperature of the non-compressor discharge. Judgment, reverse control of the electronic expansion valve, or push the wrong command to the frequency or other functions, which will further worsen the fault or expand the loss

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