APPLICATION STORY
 


        

          


          
ULTRASOUND HELPS OPTIMISE
          DRIVE DESIGNS

          
A bespoke pump
          maker is using ultrasound waves to efficiently model

          drive torque and thus contain development costs to within predictable

          limits. Charles Austen Pumps has recently upgraded test facilities
          with

          Surface Acoustic Wave (SAW) equipment from Sensor Technology,

          a recognised leader in the field.



          Charles Austen Pumps manufactures pumps individually designed
          to

          meet specific customer requirements that cannot be satisfied
          by

          off-the-shelf units. Over the three generations that this family
          firm has

          been operating it has continually honed its skills at accurately
          predicting

          development costs and working within budgets, and has become
          adept

          at using advanced techniques such as SAW analysis.

          
Much of its work
          comes down to optimising drive dynamics to produce

          the desired characteristics, be it a smooth flow in a critical
          medical

          situation, ultra low noise for pumps in home and office installations,

          or the guaranteed extra long life of pumps in inaccessible locations.

          
The cyclic nature
          typical in many pumps' operation tends to induce

          torsional oscillations in the drive shaft, which can have a significant

          adverse effect on performance if unchecked, and this is where
          much

          of Charles Austen Pumps' development effort is focussed, as technical

          Manager Brian Glover explains:

          
"We have
          recently built a new test station based on Torqsense, Sensor

          Technology's SAW sensor, and it is proving it's worth time and
          time

          again. Many years ago we used a simple torque arm and scales
          when

          developing prototype, then we moved on to slip ring technologies
          which

          were expensive and difficult to use because they induced a frictional

          load of their own."

          
"Techniques
          based on Surface Acoustic Waves began to emerge about

          10 years ago and we embraced these with considerable success."

          
SAW provides
          non-contact monitoring of instantaneous rotary torque,

          allowing accurate modelling of the load changes. Charles Austen
          Pumps

          built its own test stand and it served them well for many years.

          
"The state
          of the SAW art has now moved onto a higher plane, so last

          year we decided to tap into Sensor Technology's expertise and
          develop

          a new cutting edge test rig. They supplied us with a Torqsense
          unit and

          helped with designing and building the rig."

          
In essence a
          Torqsense is a frequency dependent strain gauge operating

          at ultrasound frequencies. It consists of a transducer mounted
          on the shaft,

          which monitors variations in resonance frequency of a drive shaft
          as the

          torsional load varies and transmits a radio frequency signal
          to an adjacent

          pick up.

          
Torqsense embraces
          all the advantages of SAW technology, including a

          broader signal bandwidth than other analogue based technologies
          and

          elimination of electronic interference. As Charles Austen Pumps
          found,

          it often also proves far lower cost, simpler to use, is more
          reliable and

          has a wider operating than contact alternatives.

          
Glover sums up:
          "Our reputation is based entirely on the quality of our

          engineering, and our business on the ability to accurately forecast

          development cost for each job. Sensor Technology has helped us
          build

          a new facility that makes our drive engineering accurate, predictable

          and reliable, or put another way we are moving from a black art
          to an

          exact science!"

          
Sensor Technology
          Ltd.

          PO Box 36, Banbury, Oxon OX15 6JB, UK

          Tel: +44(0)1295 730746

          Fax: +44(0)1295 738966

          Email: lpt@sensors.co.uk

          Web: www.sensors.co.uk

          _________________________________________________

          
December 2003

          



                
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