Archive: 11th March 2015
Prof James Turner, formerly of JLR, currently at Bath University, will present within the Engine Boosting Systems session Wednesday 22nd April, on the Ultraboost extreme downsizing engine, a project conducted with partners Jaguar Land Rover and Integral Powertrain.
The SAE 2015 World Congress attracts key individuals from the global automotive industry together with research and academic institutions committed to developing future technologies.
This year’s theme, Leading Mobility Innovation is a call to arms – a challenge to all engineers to create mobility for the future through innovative technologies.
SuperGen on Ultraboost: Variable-Speed Centrifugal Supercharging as an Enabling Technology for Extreme Engine Downsizing.
Prof James Turner of Bath University
The paper discusses investigations into improving the full-load and transient performance of the Ultraboost extreme downsizing engine by the application of the SuperGen variable-speed centrifugal supercharger. SuperGen varies the drive ratio by using a power-split gearbox and two electric machines to divide the input torque, to transmit it via two paths (mechanically and electrically) and then to recombine it in order to decouple the speed of the compressor from that of the crankshaft. It also functions as an alternator and, when equipped with appropriate internal clutches, can provide stop-start and mild hybrid functionality too, all while only requiring a 12V electrical architecture in the vehicle. Its variable ratio characteristic is potentially especially attractive in a compound pressure-charging system where a turbocharger is used as the low-pressure device, providing boost at high speed and load, and a supercharger is used as a high-pressure stage at lower charge mass flow rates, since it can be blended in and out continuously to provide seamless driveability.
In the work reported here a prototype SuperGen unit was tested on the Ultraboost extreme downsizing demonstrator engine. This engine has previously been described in detail and represents a 60% downsizing factor versus a 5.0 litre naturally-aspirated V8. The paper compares the performance of this engine when fitted with SuperGen as the high pressure stage versus that which it gave with the originally-specified positive-displacement device. In the configuration used as the baseline for this work, the positive-displacement supercharger utilized a single drive ratio and electromagnetic clutch, and this ‘standard’ combination was found in the earlier-reported work to be a limitation on achieving the full 60% downsizing factor. The improvement full-load performance in the area where the turbocharger cannot generate the required boost by itself is reported. The transient response of the combined system at various low engine speeds is also presented, together with part-load fuel economy data at several engine speed and load points. Finally, discussion is made regarding the ability of SuperGen to enable yet further engine downsizing and to improve downsized engine driveability towards that of naturally-aspirated engines of equivalent performance, together with observations on the likely further improvements in fuel economy possible were the hybridization functions it also enables to be fully utilized in-vehicle.Back to Communication