Optimum Design And Experiment Of Piezoelectric Vibrator In Tire Pressure Monitoring System Self-powered Device

These years, the cars in our country become more and more very fast. Traffic questions always emerge. Vehicles as tools for travel become popular in common family. As vehicle becomes the mainly transportation tool, more and more people focus on the safety of traveling by cars. The tire has very important position not less than the engine for cars. The pressure in the tires affects the performance and driving force. Not only affect the driving safety but also the fuel consumption. Nowadays, the TPMS on the market is mainly powered by battery, there are weaknesses in the products, such as it need change the battery when the electric in the battery is used out, the TPMS is in the tires, and it is not convenient to change the battery, at last the used-out battery is harm to environment. When the temperature is very low the battery may not supply electric, the TPMS can’t work. The products weaknesses are caused by battery, so self-powered product is trend in the future. This paper uses piezoelectric ceramics as core element of the generation device, realized TPMS self-powered.Under the subsidiary of the National natural Science Foundation Project named “The design theory and Application technology research of piezoelectric energy harvesting system bases on wheel vibration” this paper optimizes the power generation device, based on stage concept divide single silver electrode into 3 electrodes in certain proportion. The main contents are as follows:Analyzed the resonance and vibration mode in different frequency of the piezoelectric vibrator. Achieved relationship lines between the normalized strain and the length ratio by theoretical analysis and experimental verification. In different vibration mode, the nature of the charge on the silver electrode can change by the length, charge on the single silver electrode can be neutralized. To avoid this phenomenon, the silver electrode is divided into several sections, then the electric can be collected into capacitor.Though theoretical analysis, founded state space model of silver electrode segmentation piezoelectric ceramics. Introduced every parameter of the model, obtained the formula of the output voltage of every silver electrode. Introduced four connections for the collect circuit, should choose correct connection for different section mode, it can be two or more connections in parallel or serious. Computed the output voltage of piezoelectric ceramics, and verified the correctness of the result.Compared the performance of silver electrode generation electricity of three different section mode, finded the main factors affect the output power of piezoelectric vibrator, supply theoretical and technological support for the TPMS generation device optimization. As the main element of generation device, when optimize the piezoelectric vibrator, its direct evaluation standard of generation electricity can be output voltage and output power. The result of the experiments show that, the second section mode which divide the single silver electrode into three as 1:2:3, output power is highest, reduced the time of charging, and improved the electric-generation ability.Investigated the trend of silver electrode output voltage from fixed-end to free-end of the piezoelectric vibrator, the trends of six sections, ten sections, and fifteen sections are all linear declining discipline. The output voltages of the first silver electrode of three section mode are almost the same. The reason is the strain of the fixe-end is very large, becomes the most impotent factor.Fix the optimized electric-generation device to the rotating device on the electric motor in the laboratory, do the simulation experiment in the laboratory. The result shows that, the second section mode can produce enough electricity in the condition equal to the car runs on flat road. The second section mode is an effective optimization.Designed reasonable collect circuit, and choosed ordinary capacitance as the energy storage element by comparing the performance of different energy storage elements. To reduce output power consumed by internal resistance, should access an external resistance in the collect circuit, analyzed the change trend of output power adapt to external resistance, computed the external resistance, it should be equal to the internal resistance, at last verified the external resistance is about the same to the internal resistance by experiment.