Torque

Details

Category: Technologies

Published on Sunday, 04 January 2009

In a typical modern vehicle's Engine Control Unit ('ECU'), torque is inferred from in-vehicle sensors measuring air and fuel flow, temperature and ignition timing in conjunction with 'look-up tables' derived from dynamometer tests of sample engines by the vehicle manufacturer. The problems associated with this approach are that, due to manufacturing tolerances, engines are not identical and they change their characteristics over their service life. Accurate real-time torque measurement can improve engine control, resulting in better fuel efficiency and can also provide for smoother ratio changes within automatic transmissions improving NVH (noise, vibration and harshness) and perceived quality. Torque measurement in driveshafts and torque splitters enables better control of actual torque to the individual road wheels for stability and traction control in four wheel drive vehicles. Specific applications of Transense's SAW torque sensors include:

• Electrical Power Assisted Steering
• Flexplate: situated between the crankshaft and torque convertor, the flexplate sensor provides direct measurement of engine output torque for engine and transmission control
• Transmission output shaft: provides real time torque information to optimise the control of automatic transmissions
• Torque splitter: enables optimised torque distribution between axles in 4WD applications
  
• Driveshaft: individual sensors enable torque vectoring for improved stability control during cornering

Contactless Torque Transducer

• Two SAW resonators on a single quartz die
  
• Hermetic package
• A pair of RF couplers
• An annular PCB carrying RF ASIC and DSP

Torque sensors - New Generation

• Enhanced torque sensor die incorporating temperature resonator
• Improved bonding: die to package; package to structural component