Although car engines are major contributors to carbon build up, they are fundamental to modern life – so ensuring they are as efficient as possible is essential.
One area of inefficiency is the engine lubrication system. These have a simple mechanical pump which has been sized to ensure an adequate supply of oil in the worst operating condition. The pump is therefore hugely oversized for most of the rest of the speed range and, as a consequence, nearly 60% of its output is dumped straight back into the sump via the relief valve. It will also deliver the same amount of oil to every part of the engine regardless of what that system might actually need; and is also insensitive to engine load, so the bearings will receive the same oil supply at a given speed regardless of the load. The pump also forces nearly a ton of oil per hour through the filter, and when the oil is cold this takes a huge amount of energy.
As an alternative, a UK company asked Powertrain Technologies to design an intelligent lubrication system and to analyse its effects on engine friction and parasitic losses. To meet requirements, the company built a highly specialised test rig featuring a TorqSense transducer from Sensor Technology.
The engine under test was a current production diesel and the test bed was configured for motored friction tests with a 6,000rpm 32kW electric motor. Powertrain completely re-designed the engine lubrication system and installed a bank of five computer controlled oil pumps. Each is capable of supplying individual parts of the engine with oil under conditions unique to that part of the engine and sensitive to the engine operating conditions.
The idea was to completely profile the performance of the engine under various lubrication conditions and to derive optimum configurations of the intelligent systems for best performance.
The torque sensor is critical to the project since the object of the exercise is to measure the effect on friction of a range of different oil supply strategies and oil types. Thus the changes in friction are represented by a change in the motored drive torque of the engine.
Andrew Barnes, a director at Powertrain, said: “Both petrol and diesel engines run far cleaner than they did 20 or 30 years ago. However the need to operate efficiently under a wide range speeds, loads and environmental conditions from -40°C to + 40°C remains the Achilles Heel. Intelligent lubrication has the potential to improve performance no end, although quantifying the best configuration is painstaking work.”
TorqSense sensors are particularly appropriate for development work because they are wireless fit-and-forget, non-contact, digital sensors, explains the company.
Powertrain’s research has now progressed to the next stage in which the test rig is forsaken and the engine installed in a car to quantify the effect on fuel economy.
“It’s now a matter of driving it under all sorts of conditions on a mixture of test tracks and rolling roads to build up profiles of fuel consumption,” concluded Barnes.
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