9 - TEXAS A&M UNIVERSITY TEXAS A&M UNIVERSITY Sensors...

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T E X A S A & M U N I V E R S I T Y DEPARTMENT OF MECHANICAL ENGINEERING TEXAS A&M UNIVERSITY COLLEGE STATION, TX 77843-3123 979 845 1251 FAX 979 845 3081 1 of 31 R. Langari, 10/2/09 Sensors Functional Basis of Sensors Key Ideas: (Clever)use of some natural effect to convert(transduce) the quantity of interest (temperature, pressure, acceleration, etc.) into one that is more readily measurable(displacement, current, voltage, etc.) Mercury-in-glass Thermometer Tire pressure Gauge Seals Piston Piezoelectric Force Sensor T E X A S A & M U N I V E R S I T Y DEPARTMENT OF MECHANICAL ENGINEERING TEXAS A&M UNIVERSITY COLLEGE STATION, TX 77843-3123 979 845 1251 FAX 409 845 3081 2 of 31 Sensors... R. Langari, 10/2/09 Classification of Sensors I. Mechanical Operation A. Contacting spindle, pin, or finger Displacement to displacement B. Elastic member 1. Load cells (Chapter 13) a. Tension/compression Force to linear displacement b. Bending Force to linear displacement c. Torsion Torque to angular displacement 2. Proving ring (Chapter 13) Force to linear displacement 3. Bourdon tube (Chapter 14) Pressure to displacement 4. Bellows Pressure to displacement 5. Diaphragm (Chapter 14) Pressure to displacement 6. Helical spring Force to linear displacement T E X A S A & M U N I V E R S I T Y DEPARTMENT OF MECHANICAL ENGINEERING TEXAS A&M UNIVERSITY COLLEGE STATION, TX 77843-3123 979 845 1251 FAX 409 845 3081 3 of 31 Sensors... R. Langari, 10/2/09 Mechanical Cont’d Operation C. Mass 1. Seismic mass (Chapter 17) Forcing function to relative displacement 2. Pendulum Gravitational acceleration to frequency or period 3. Pendulum (Chapter 13) Force to displacement 4. Liquid column (Chapter 14) Pressure to displacement D. Thermal (Chapter 16) 1. Thermocouple Temperature to electric potential 2. Bimaterial (includes mercury in glass) Temperature to displacement 3. Thermistor Temperature to resistance change 4. Chemical phase Temperature to phase change 5. Pressure thermometer Temperature to pressure T E X A S A & M U N I V E R S I T Y DEPARTMENT OF MECHANICAL ENGINEERING TEXAS A&M UNIVERSITY COLLEGE STATION, TX 77843-3123 979 845 1251 FAX 409 845 3081 4 of 31 Sensors... R. Langari, 10/2/09 Mechanical Con’td Operation E. Hydraupneumatic 1. Static a. Float Fluid level to displacement b. Hydrometer Specific gravity to relative displacement 2. Dynamic (Chapter 15) a. Orifice Fluid velocity to pressure change b. Venturi Fluid velocity to pressure change c. Pitot tube Fluid velocity to pressure change d. Vanes Velocity to force e. Turbines Linear to angular velocity
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