| 摘要 |
PURPOSE:To make the apparatus compact and to improve durability, by freely vibrating a piezoelectric vibrator in a fluid, and measuring viscosity, density, or the like of the fluid based on the vibrating vehavior. CONSTITUTION:When a vibrator 1 is connected to the side of an amplifier 2D, the vibrator 1 is vibrated. When the vibrator 1 is connected to the side of differential amplifier 2G, the vibration is stopped. The output voltage signal of the vibrator 1 accompanied by the free vibration is amplified by the differential amplifier 2G and outputted as a signal (a). The signal is read by an operating circuit 2M as peak value data. The output signal of a temperature sensor 4 is inputted to a temperature detector 2A and read by the operating circuit 2M as temperature data T. An average value C of logarithmic attenuation rates B(i) is computed for each peak value data, and viscosity X corresponding to the value C is computed. The deterioration limit viscosity Xo(T) of oil and the viscosity X are compared. When the viscosity X exceeds the limit viscosity Xo(T), a warning light 5 is lighted, and driver's attention is attracted. |
