Product category:
Position, speed and torque measurement
News Release from: Sensor Technology
Edited by the Processingtalk Editorial
Team on 17 December 2002
New transducer for measurement of rotary
torque.
Sensor Technology has announced their new range of Rayleigh wave TORQSENSE transducers, for the measurement of rotary torque, using patented SAW technology
Sensor Technology Ltd announces their new range of Rayleigh wave TORQSENSE transducers, for the measurement of rotary torque The Sensor Technology experience of working with this relatively simple patented technology also means that it can now be embedded into OEM products where knowledge of torque is critical
This article was originally published on Processingtalk on 7 Mar 2006 at 8.00am (UK)
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TORQSENSE transducers are available in 7 sizes, to measure torque from 100mNm to 10,000 Nm, with smaller ranges having speeds up to 30,000 rpm.
The advantages of using SAW devices in torque transducers are that they are relatively simple and require a minimum shaft length and relatively high stiffness of shaft.
They are also suitable for cost sensitive applications, being low in cost: rotary torque has historically been difficult and expensive to measure Rayleigh wave transducers also have low inertia, require no physical contact between the housing and shaft, and are not speed dependent.
Further reading
Non-contact rotating shaft torque measurement
Measuring the torque of a rotating shaft has always been a bit of a nightmare because the necessary contact slip rings tend to be rather fragile and unreliable
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Expansion plans have been put in train at high technology torque measuring company Sensor Technology, with a move to additional premises for the operational staff to prepare for future growth
The patented TORQSENSE uses SAW devices as 'frequency dependent' strain gauges to measure the change in resonant frequency caused by the applied shaft strain.
By using a frequency-based device, the signal bandwidth is increased, and the problem of electronic interference common with other analogue based technologies is eliminated.
In a TORQSENSE transducer, surface waves are produced by passing a high frequency voltage across the terminal of two interleaved comb-shaped arrays that are layered onto one end of a piezoelectric substrate.
A similar 'receiving' terminal, at the other end of the transducer, converts the wave back in to an electric signal.
The frequency of the wave generated is dependant on the spacing of the 'teeth' in the comb array and as the direction of the wave propagation is at right angles to the teeth, any change in its length alters the spacing of the teeth and hence the operating frequency.
To measure torque in a shaft, two SAW transducers are bonded at 45 degrees to the shaft axis and connected in a 'half bridge' configuration.
When the shaft is strained, the difference in frequency output between the two SAW devices relates to the applied torque.
TORQSENS transducers require no physical contact between the housing and shaft: instead, the signals are transmitted via a rotor and stator.
TORQSENSE offers high bandwidth and excellent signal immunity.
The transducers are available with RPM output and IP65 sealing as options, and interface with the E302 Advanced Torque Transducer Display, which features full temperature correction for changes in the modulus of elasticity of the shaft.
The E302 can be interfaced with TORQVIEW Virtual Instrumentation Display PC Software to give a self-contained data display and recording system.
OEM applications for TORQSENSE include automotive, manufacturing machines, condition monitoring, tightening procedures, and monitoring and control of viscosity during mixing processes. Request free introductory details about products from Sensor Technology ...
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