Engines of the future

MAHLE takes a peek into the future

Published:  20 March, 2015

A great many professionals in the motor trade respect the MAHLE brand for premium quality filters and engine components, and thanks to its vital role underpinning the Audi Sport team's string of successes at Le Mans, so do thousands of motorsport fans around the world.

However, not so many yet know much about another cutting edge role the German parts supplier is taking in the drive towards the everyday use of less polluting and more fuel-efficient cars. MAHLE Powertrain engineers have been busily working on future concepts over the last decade and have had a full-scale engine downsizing prototype on long term test over a wide variety of normal road conditions, for more than three years.

At the heart of this project lies a frugal 1.3-litre three cylinder petrol engine, built entirely from the ground up by the company's engineers, using many parts supplied as original equipment to vehicle manufacturers. This engine powers a Volkswagen Passat estate in place of the standard car's 1.8-litre engine. The turbocharged MAHLE motor features the latest Start-Stop technology and has a 120 kW power output, with 286 Nm maximum torque between 1,600 - 3,500rpm. In old money, that's around 160bhp!

Fuel economy of 49mpg for the New European Driving Cycle and CO? emissions of just 135 g/km are equally impressive for a full size family estate with such a small engine. Developed by MAHLE to provide a platform for future petrol engine R&D technology, no other engine component manufacturer has a downsizing engine programme like this.

By moving R&D out of simulation in the laboratory and into practical driving situations on the open road, new technologies for future generations of engines can be fully tested, giving MAHLE the ability to provide car manufacturers with already proven powertrain solutions to meet future market demands.

Electric range anxiety - the MAHLE solution

The compact range extender, which was developed by MAHLE in 2011 and installed in a demonstration vehicle for test purposes, has an output of 30 kW and was designed for a maximum vehicle weight of 1,600Kg.

For heavier cars and luxury vehicles or minibuses and vans, a correspondingly higher engine output is necessary. In-vehicle simulation showed that an output of 40 kW is required for vehicle weights of up to 2,100Kg and for even heavier vehicles, an engine output of 50 kW was ideal.

In developing the output-enhanced versions, MAHLE engineers placed particular importance on maintaining the compact dimensions of the original engine and used the highest possible number of identical parts in order to ensure efficient and cost-effective series production.

For both the more powerful versions, it was decided that the maximum peak cylinder pressure of 75 bar should be maintained. Flow calculations proved that an output of 40 kW is already feasible with an increase in the rated speed from 4,000 to 5,500 rpm, while further analysis showed that a 50 kW version of the range extender engine could be achieved by increasing the rated speed and in conjunction with turbocharging of up to 0.5 bar.

Based on the weight and installation volume of the 30 kW range extender engine, MAHLE engineers were able to calculate, simulate and realise the necessary higher speeds for the 40 kW version by providing additional protection for engine components such as the intake system, valve train and crankshaft.

Compressor boosts compact 50kW engine

In the turbocharged variant, the installation space increases from a box volume of 65 to 85 litres and the weight of the engine generator unit by almost 5Kg to 70Kg. In a series solution, the electric compressor can be controlled directly by the range extender's engine control unit and the power electronics can be integrated into those of the generator.

Current engine tests will show what impact this very compact arrangement without intercooling has on both combustion and knocking behaviour, as well as on the overall efficiency of the 50 kW range extender and therefore, what an optimal series concept for heavy vehicles will look like. So watch this space!


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