Quartz Tuning Fork Oil Sensor Design

Lubricating oil quality directly determined the service life of industrial equipment. At present, most oil quality sensor is capable to measure the oil medium single physical quantity only but cannot to realize comprehensive assessment of oil quality, which showed that multi-parameter measurement is the development trend for intelligent sensor technology. Therefore, developing a sensor can be used in the oil medium for multi-parameter measurement is quite have the research significance and application prospect.As the quartz tuning fork is sensitive to physical parameters of oil medium, a density and viscosity testing system with CAN bus communication based on the impedance frequency characteristics of quartz tuning fork in oil medium is designed. First of all, through the analysis of existing sensors technology for oil quality monitor, a quartz tuning fork is chose as sensitive element. Then, quartz tuning fork vibration modal and piezoelectric characteristics are analyzed to study the principle of measurement the oil density and viscosity, and the overall scheme of the system is given to further analysis of the subject. The system hardware with ARM7microprocessor as the core, included direct frequency synthesis source module, impedance readout and signal conditioning module, signal acquisition module, CAN bus data communication module and DC power management module, and the EMC design is also carried out to ensure the anti-interference capability of the whole system. On this basis, the DDS control software, CAN Bus communication software and data acquisition software are designed on ARM Development Suite, and the data processing and display interface are designed in host-computer. Finally, quartz tuning fork sensor and standard oil is prepared, a platform for debug the testing system is constructed, the experimental result shows that the system can realize the oil medium viscosity and density monitoring simultaneously, the measuring range of the density is0.819～0.911g/cm3with the error within7.5%, the measuring range of the viscosity is2.85～14.98cP with the error within7.2%.