A system that uses ultrasound technology to look inside car engines could lead to more efficient engines -- and huge fuel savings¹ for motorists. Ultrasound scans have long been a fundamental tool in healthcare for looking inside the human body, but they have never before been put to use in testing the health of a modern combustion² engine（内燃机）.

 

In the University of Sheffield's Department of Mechanical Engineering, Rob Dwyer-Joyce, Professor of Lubrication Engineering, has devised a method of using ultrasound to measure how efficiently³ an engine's pistons⁴（活塞） are moving up and down inside their cylinders⁶.

 

"There is a real urgency, now, to improve energy consumption in cars," says Professor Dwyer-Joyce. "Our method will allow engine manufacturers to adjust lubrication（润滑） levels with confidence and ensure they are using the optimum level for any particular engine, rather than over-lubricating to ensure engine safety. The energy used by the piston⁵ rings alone amounts to around 4p in every litre of fuel -- there is a lot at stake in getting the lubrication right."

 

The seal between piston rings and cylinder⁷ is the most important seal in the entire engine and understanding how the lubricant works inside this sealed chamber⁸ is crucial for improving the fuel efficiency of the engine.

 

The movement of the pistons is what drives the car forward. Car manufacturers have to calculate how much oil will allow the piston to move efficiently. Too much oil is wasteful⁹ and ends up getting burnt in the engine -- increasing emissions¹⁰, while too little will result in wear from the two moving parts rubbing against each other.

 

Because cylinders are enclosed spaces, it is not easy to test what is going on inside. Computer models don't effectively allow for changes as an engine speeds up and gets hotter, and more invasive methods -- cutting open the cylinder -- interfere¹¹ too much with the mechanism¹² to get an accurate test result.

 

The Sheffield team are measuring the lubricant film by transmitting ultrasonic¹³ pulses through the cylinder wall from sensors¹⁴ attached to the outside. The reflections from these pulses can then be recorded and measured.

 

The research is part of a project funded by the Engineering and Physical Sciences Research Council. It has included collaboration¹⁵ with Loughborough University, which is overall leader on the project, and Cranfield University, and a host of automotive industry manufacturers and suppliers. The research team at Loughborough is investigating the piston-cylinder dynamics¹⁶ and tribological modelling, the development of predictive tools, advanced cylinder liners and surface laser texturing¹⁷, and the direct measurement of friction¹⁸, whilst the team at Cranfield have been studying the micro-scale interaction between the piston rings and the cylinder.

 

The team is ready to commercialise this technology and is looking for industrial partners who might be interested in pursuing the approach.

 

"Our system could provide major efficiency savings in car engines, but it could also be used on the larger diesel¹⁹（柴油） engines in deep water marine²⁰ vessels²¹, some of which use up to 1 tonne of oil each day," adds Professor Dwyer Joyce.

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