ETH-messtechnik DRVL, Руководство оператора

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3. Description and functionality of the device
3.1 Torsional shaft
The torsional shaft is constructed with special aluminum or hardened carbon
steel to suit the full-scale value.
Strain gauges attached to the torsional shaft sense the shaft torsion, which is
proportional to the torque and is within its elastic range. The strain gauges are
arranged as a Wheatstone bridge circuit. The force is transmitted via cylindrical
shaft extensions with smooth shaft extensions or a featherkey as per DIN 6885.
A pulse disk for speed or rotation angle measurement can be fitted to the torsio-
nal shaft if needed. Please refer to the data sheet for more details.
3.2 Enclosure
The enclosure for the torque transducer is made of high-strength aluminum; the
enclosure surface is hard-anodized to protect it. The torsional shaft is supported
in the enclosure with two deep-grooved ball bearings. The transducer can either
be base mounted or flange mounted. An electronics module for conditioning
and analyzing the signal for torque, speed or angle of rotation is installed in the
enclosure.
3.3 Principle of operation
The torsional shaft, and thus the strain gauges, are elastically deformed by the
torsional force. The ohmic resistances of the strain gauges change proportional
to their change in length. The electronics module is connected in series and it
transfers the measurements by means of optical frequency modulation to the
enclosure.
The signal is then converted by the external electronics unit to an analog voltage
that is proportional to the change in frequency. Those signals and frequency
output are available as an electrically isolated signal for further processing.
The pulse disk on the torsional shaft is sampled with an encoder in the enclosure.
Two waveforms are available for analysis: (1) a square wave with 60 pulses/turn
for the speed option, and (2) two square waves offset by 90° with 360 pulses/
turn for the angle of rotation option.The direction of rotation can be detected
with the angle of rotation option. Channel A leads channel B by 90° for clockwise
rotation.