Instrumentation and Control News

The torque-current characteristics of a combined motor-generator developed for a Lotus-based hybrid car have been comprehensively mapped by a TorqSense digital torque sensor.

 

Specialist electromagnetic design company Elektro Magnetix (EMX) of Brighton developed and tested the motor-generator for Lotus Engineering’s EVE(Efficient, Viable, Environmental) Hybrid. This is a technology demonstrator that is showcasing many of the medium term solutions that will be used to reduce vehicle emissions.

 

A test rig built at Centa Transmissions in Shipley is allowing the company to guarantee that the precision gearboxes it supplies to nuclear industry will never fail prematurely. Despite its critical role, the rig is essentially quite simple, in that a motor drives the test unit against a load created by one of Centa’s own industrial disc brakes. The test runs initially for three hours at the full working load, and then is increased to 300 percent load for another hour. At the heart of the rig is a non-contact sensor that constantly monitors the torque in the gearbox, generating a performance profile that can be compared with the ideal performance standard.

Cold extrusion is playing an ever greater part in recycling of waste plastic, and the Department for Business and Enterprise is sponsoring research into development of the machinery necessary for such work.

Engineers at Bradford University have built a pilot plant and are running a series of trials with different processes, feed plastics, additives, and final products. Leader of the project, Dr Raj Patel explains:

"We started out comparing cold extrusion and warm extrusion, in which the material is heated prior to processing, and quickly realised that cold extrusion was more suited to recycled plastic. Our process now is to granulate the recycled materials to a consistent size, mix in binders as appropriate to basically, glue the particulates back together, and cold extrude it into sheets or blocks.

Fast`s technique - on which there are 20 patents pending - is to magnetise the shaft and to sense the changes in the magnetic field that occur when torque is applied. These changes are detected by a sensing head typically placed about 1mm from the shaft, and are then converted into an electrical signal by conditioning electronics

The TMF transducer, developed jointly by Magtrol (formerly Vibro-meter`s instrumentation division) in Switzerland, and GIF in Germany, uses strain-gauge measurement. The sensor is available in rated torques of 450, 1,100 or 2,800Nm, with the optional second measuring range typically being rated at 1/10 of the nominal torque.

The Type 4504A torque sensor from Kistler Instruments is suited to applications where space is at a premium and operating conditions are far from ideal

Kistler Instruments has developed a robust, non-contact torque sensor with integrated digital signal processing called the Type 4504A

At the heart of the TorqSense sensor is pair of tiny, interleaved, comb-shaped arrays laid onto one end of a piezoelectric substrate. By passing an alternating voltage across the terminals of these arrays, surface waves are produced in the substrate. The waves are received by a similar array at the other end which converts them back into an electric signal.

Unlike traditional slip-ring transducers, the TorqSense sensors provide a simple non-contact technology for measuring the power in drive shafts and other rotating elements. Torsion is sensed by a pair of SAW strain gauges bonded to a shaft at right-angles to each other. One senses compression and the other tension, and this information is transmitted via a radio frequency couple to the decoding electronics which generates outputs for torque, speed, power and angle.

A torque sensor is helping analyse recipes’ mixing properties in a project that could slash development costs in the food and plastics industry and help nanotechnology advances in the pharmaceuticals world.