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Hybrid Powetrain
The Challenge
Wrightbus of Ireland, in conjunction with
Transport for London had embarked on the
development of a new hybrid PSV vehicle to
meet the Low Carbon bus emission targets set
out by the UK government. An initial concept
had been derived using an existing city bus
combined with a 4 cylinder 1.9 GM, 150 hp
diesel unit and an Enova generator unit.
Millbrook were then approached to support
the development of the concept into a
validated and proven vehicle. The key
challenge for this programme was to
establish a test and development programme
that would achieve effective, efficient and
reliable operation of the vehicle in a tough
urban environment. Integration of the
vehicle, engine, generator and control
system became central to the success of the
project from an early stage.
The Millbrook Approach
To establish the potential for the improvements in emissions, Millbrook used its extensive experience to benchmark the emissions performance of the 1.9 diesel power train and using this data simulate the benefits that could be achieved when the unit was subjected to PSV drive cycle.
Recommendations for the vehicle targets were made and once agreed Millbrook took a central role in supporting the development of the prototype vehicle, including the provision of design advice in a number of key
areas including engine ECU mapping and hybrid controller integration. Once built and running, the prototype vehicle underwent an extensive shakedown and test programme to ensure reliable operation of the new hybrid drive system. Key test and development activities included;
- Drive system Integration and calibration
- Engine cooling
- EMC
- Noise
- Brake performance
- Vehicle durability and validation
Towards the end of the programme Millbrook’s VETC was used to develop a complete ECU map to optimise emissions, economy and performance of the complete hybrid vehicle.
The Solution
Through a close working partnership Millbrook was able to offer a unique solution that resulted in significant savings in fuel economy and emissions. Results of a fully developed product in operation in London show an improvement of 40% in fuel economy and 38% in CO2 compared against the Euro 3 engine version. In fact, it is understood that use of the smaller lighter engine has improved passenger comfort due to lower levels of noise and vibration in the passenger compartment.
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