High performance torque measurement is helping to improve the energy efficiency of domestic washing machines. The solution involved technology transfer from other fields of engineering. Technical Director Andrew Stephen explains: “Washing machines energy is delivered through their main drive motor. Front loaders are horizontal axis, so the load is being lifted on one side of the axis and falling on the other. We wondered if this offered possibilities for regenerative energy recovery.

Stephen built a test rig to subject a washing machine to extensive tests using an inverter to simulate the washing cycles. A critical element was the ability to make continuous accurate torque measurements, and for this he used TorqSense transducer from Sensor Technology which uses a non-contact radio frequency link that does not add an extra drag load to the results, nor affect the dynamic changes in torque as the load went over ‘top dead centre’.

By measuring the torque he could switch the drive from power to regeneration to use the energy released by the falling load. “This technique is worth building into next generation washing machines” says Stephen. “With a full load of heavy cottons plus a drum load of water you get a 15percent energy reduction.”

Sensor Technology Ltd is based in, Upper Heyford, Bicester, Oxon, UK. www.sensors.co.uk