Study On Sensing Mechanism Of Gas Pendulum Tilt Sensor And The Key Factors Of Affecting Its Property

Gas pendulum tilt sensor was researched and developed due to the "pendulum" characteristic of natural convection in a hermetic chamber. Because the mass of gas is small and there is no proof mass , the gas pendulum tilt sensor has large-scale applications for its characteristic of resisting oscillation and shock. But the research and development of the gas pendulum tilt sensor was based on the experiments, there needs further study in theory. For example, the effects of natural convection and heat radiation in the hermetic camber on the output charaeteristics of the sensor are still open problems. Aiming at the above problems, the following studies are conducted in this paper:First of all, the mechanism of tilt sensor is analyzed and different output characteristics of several sensing structures of such sensors are discussed in this paper. Through the establishment of control equations and boundary conditions, the natural convection in the hermetic chamber is simulated. Based on these results of the simulations, the sensing mechanism of the gas pendulum tilt sensor is analyzed. And then different output characteristics of several sensing structures of such sensors are anatomized.Secondly, heat transfer problems of gas pendulum tilt sensor are analyzed in theory. According to different mechanisms of conduction, convection and radicalization heat transfer, relevant physical models are established for the heat transfer of the sensing organ. Based on these models, the heat transfers of conduction, convection and radicalization of the sensing organ in the hermetic chamber are calculated. The results indicated that radicalization of the sensing organ in the hermetic chamber is very small and can be neglected for the analysis of heat transfer. Heat conduction in the hermetic chamber is equal to heat convection; so simplified heat transfer analysis can be made by analysis of heat conduction for the heat transfer analysis in the hermetic chamber of such a sensor.Whereafter, the compensating method of sensitivity temperature drift was discussed in this paper. As well known, the influence of environmental temperature is strong on the property of gas pendulum tilt sensor, and is the key factor for its property. How to eliminate the influence of environmental temperature is an open problem for the research and development of gas pendulum tilt sensor. According to flow similarity, a active compensating method of eliminating sensitivity temperature drift was proposed in this paper, and then the feasibility study of such a method is conducted by experiments. Compensating circuitries is designed for this active compensating method, and the advantage of such a method was validated. Experiment results show that sensitivity temperature drift is minished by 70% because of the introduction of the compensating circuitries.Otherwise, detecting circuitries of the gas pendulum tilt sensor are also optimized in this article. SCM substitutes for circuitries of amplifier and filter, and digital amplifier and filter was introduced in the detecting circuitries. Stability of product is improved; zero drift is reduced, volume is minished, cost is low. In the end, the electrical performance testing at normal temperature and environment temperature testing on completed sensor has been finished. The results of testing are satisfied with the demand of the design.As masterstroke and linker natural convection in hermetic chamber was studied. Based on numerical simulation, the theoretical analysis of effects of the key factors on the property of the sensor was conducted; gas pendulum tilt senaor's mechanism is explained. According to the flow similarity, the compensating method of eliminating sensitivity temperature drift was proposed.The main innovative views in this paper are as follows:(1) The relationship between the output property of the tilt sensor and the temperature and velocity of the natural convection in the hermetic chamber was first established and studied quantificationally. Results show that the effect of temperature on the output property is far larger than that of velocity in gas pendulum tilt sensor with a single heat source.(2) For the first time, the physical models of heat transfer analysis of the hermetic chamber of gas pendulum tilt sensor are established according to the different heat transfer mechanism. The conduction, heat convection and heat radiation in the hermetic chamber are analysed quantificationally. Results show that the heat radiation can be canceled in the analysis of output property.(3) According to flow similarity, a active compensating method of eliminating sensitivity temperature drift was proposed, and then the feasibility study of such a method is conducted by experiments. Compensating circuitries is designed for this active compensating method, and the advantage of such a method was validated.