Reduction in Parasitic Losses by Careful Choice of Alternator Drive System Mahle Powertrain, Limited

Format:

Conference/Event

Author/Creator:

Mackay, Mackay, author.

Conference Name:

SAE 2012 World Congress & Exhibition (2012-04-24 : Detroit, Michigan, United States)

Language:

English

Physical Description:

1 online resource

Place of Publication:

Warrendale, PA SAE International 2012

Summary:

Concerns over greenhouse gas emissions are driving governmentsand the automotive industry to seek out ways of reducing vehicleCO₂ emissions. Engine friction reduction is one means of reducingCO₂ emissions, through fuel consumption improvements. The ancillarydrive system typically contributes up to 8% of the total enginefriction level, so improvements in this system can make a realdifference to engine efficiency, fuel consumption and CO₂emissions.Mahle has undertaken a series of rig tests, based on a 2.5-litergasoline engine, but built to a minimum friction level of hardware.Using motored drive torques, the losses associated with differentalternator drive concepts was investigated: - Standard 150Aalternator, - Reduced capacity 120A alternator, - Reduced capacity120A alternator driven by a dual speed gearbox, and - Reducedcapacity 120A alternator driven by a twin-belt dual ratiopulley.The engine test configuration enabled the friction sensitivityto be considered in respect of oil temperature, belt tension, belttemperature and alternator loading, as well as the hardware changesconsidered.The twin-belt concept demonstrated a friction improvementcapability, whereas changing the effective alternator ratio bymeans of a dual speed gearbox demonstrated a detriment. The use ofa twin-belt system could offer the opportunity to reduce theoverall FEAD system losses as well as potentially enabling smalleralternators to be specified. Cost and packaging issues permitting,this could reduce the parasitic losses associated with analternator drive system.With a twin-belt arrangement, the test engine demonstrated animprovement in net parasitic losses of between 300W and 400W, at anengine speed of 5000 RPM and alternator loading of 60A. For thesame test conditions, a dual speed gearbox would need to beoperating at an efficiency above approximately 80% to avoid a networsening in parasitic losses, whilst the measured efficiency ofthe test unit was approximately 60%.This paper considers the approach to the testing, the testresults obtained and some further discussion

Notes:

Vendor supplied data

Publisher Number:

2012-01-0385

Access Restriction:

Restricted for use by site license