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Hydraulic Projects (Hy-Pro), a developer of hydraulic drive units for marine steering and autopilot systems, is using Torqsense wireless torque sensors from Sensor Technology to design pump assemblies used in the hydraulic steering systems of yachts and other small pleasure craft.

The sensors, which are designed to measure shaft torque in rotary drive systems, are providing the data that Hy-Pro needs to refine the design of its electrically powered pump assemblies.

Developing pump assemblies for marine applications in small vessels is said to be challenging. In order to ensure that its products satisfy a range of requirements, the company searched for an accurate measurement solution and made the decision to use Torqsense devices.

The sensors measure the torque delivered by the electric drive motor to the pump, under varying loads and over a wide range of speeds, in a purpose-built test rig.

Key benefits of product application

  • The Torqsense devices — which are based on surface acoustic wave (SAW) transducers — ensure economical operation and enable the steering systems to continue to operate reliably in heavy seas and in bad weather.
  • According to Barry Wynn, senior design engineer at Hy-Pro, the sensors deliver the accuracy and fast response required; they are also said to be reliable, easy to use and cost effective.
  • The Torqsense sensors incorporating SAW transducer technology can be used on rotating shafts and can provide data continuously without the need for the unreliable brushes and slip rings that are often found in traditional torque measurement systems.
  • Wynn said that the data Torqsense has provided has played an important role in helping the company to refine its systems by ensuring a good match between the characteristics of the pump and motor over the full operating range.

Sensor Technology

Sensor Technology are manufacturers of TORQSENSE Transducers, the world’s first low cost non-contact rotary torque transducers designed for OEM applications. Rotary torque measurement has always been difficult and expensive.

The patented method uses a surface acoustic wave device as a frequency dependent strain gauge and measures the change in resonant frequency caused by the applied strain in the shaft.

The signal is transmitted via an RF couple from the rotating shaft to a fixed pick-up.

By using a frequency-based device, the signal bandwidth is increased, and the problem of electronic interference common with analogue signals is eliminated. The torque sensors are designed to operate direct from a PLC or a PC.

They require minimum length of shaft, have low inertia, no physical contact between shaft and housing, wide bandwidth, high resolution and accuracy resolution to better than one part in a million, and excellent noise immunity.

The technology lends itself to design of OEM transducers for specific customer applications. Applications include automotive, manufacturing machines, condition monitoring where knowledge of torque is critical, torque control of tightening procedures, and monitoring of viscosity during mixing where consistency is required. The technology replaces existing types of rotary torque sensors by providing better performance at a lower price.

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