Lotus Engineering and its major shareholder Proton Holdings Bhd have come together in a R&D project styled ‘EVE Hybrid’ (Efficient, Viable, Environmental) technology demonstrator. The aim of the project, showcased at the 77th Geneva International Motor Show, was to demonstrate how OEMs can introduce lower emissions variants to existing model ranges that offer conventional gasoline and diesel powertrains.
A cross-functional team of Lotus and Proton engineers worked seamlessly together at Lotus Engineering’s Hethel headquarters and Shah Alam, Kuala Lumpur. EVE is based on the Proton Gen. 2 compact midsize car with a 1.6 litre gasoline engine, and features a ‘micro-hybrid’ start-stop system, a full parallel hybrid drive and continuously variable transmission (CVT) technology. When compared to the baseline Proton Gen. 2, the result is a reduction in CO2 emissions by 22 percent and a 25 percent improvement in fuel economy to 50.2 mpg.
Lotus Engineering believes the application of hybrid technology is a key route for CO2 emissions reduction. For the next five years, it may remain more viable to integrate hybrid technologies into existing model ranges than to develop expensive new dedicated hybrid platforms, it said. And so the EVE Hybrid programme is focused on establishing the processes for integrating hybrid technology with minimal development time and cost, overcoming many challenges associated with integrating hybrid technology into existing platforms through intelligent, compact and discreet packaging of systems.
HYBRID INTEGRATION
“As an automotive consultancy and global OEM, Lotus is able to manage all elements of a hybrid integration project under one roof, with extensive drivetrain, vehicle, electrical and control systems expertise from design and development through to production. Our technologies and world-class engineering capabilities mean we are in a great position to help OEMs apply advanced hybrid technology to their products in order to reduce average CO2 emissions,” said chief executive officer, Group Lotus Plc, Mike Kimberley.
More importantly, the EVE Hybrid technology demonstrator is equipped with a number of production-ready technologies. It has employed systems deliberately sourced from established tier one suppliers in order to demonstrate the availability of components, the minimisation of development costs and to maximise business case viability.
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COMBINING FUNCTIONS
The ‘Micro-hybrid’ stop-start system switches the engine off when the vehicle stops and restarts it automatically when the brake pedal is released. This unit runs on the standard vehicle 12 volt electrical system and combines both starter motor and alternator functionality. It has demonstrated the unit fuel savings of five percent with a five percent reduction in CO2 emissions.
The hybrid system uses a bespoke 30kW, 144V motor that is packaged between the engine and transmission. It delivers electric drive or regenerative braking via an additional clutch linking the motor to the drivetrain. The motor provides the same start-stop functionality as the micro-hybrid with the additional benefit of electrical drive or drive assist, either boosting the drivetrain performance or providing economy and emissions benefits by operating as an electric vehicle.
The motor is powered by a 144 volt battery located in the boot. Lotus Engineering said testing has confirmed simulation predictions of 28 percent fuel efficiency improvement and 22 percent CO2 emissions reduction. In addition, the integration of a CVT gives benefits in fuel consumption and emissions control. Its compact package also assisted in the application of a hybrid electric drive and it provides smooth acceleration and low transmission noise.
Naturally, there have been several changes made on the technical side. For starters, various changes have been made to the Proton gasoline 1,597cc CamPro engine. The main modification is the redesign of the front end accessory drive (FEAD) to accommodate a Valeo ‘StARS’ starter/alternator, which drives the micro hybrid start-stop system. The redesigned FEAD also accommodates a Sanden hybrid Heating Ventilation and Air Conditioning (HVAC) compressor that operates by conventional belt drive and has an additional electrically driven capability which enables continued air conditioning operation when the engine stops.
EMS UPDATED
During the FEAD redesign the opportunity was also taken to replace the belt driven Power Assisted Steering (PAS) and water pumps with electric units to enable the investigation into the economy benefits of such units. To accommodate the additional hybrid functionalities the Engine Management System (EMS) was updated to a Siemens VDO torque-based unit and re-calibrated by Lotus Engineering.
In the case of the motor/generator, bespoke electric motor and power electronics were developed in conjunction with specialist suppliers ElektroMagnetix and Turbopower Systems. The motor/generator and power electronics are water-cooled and include an auxiliary power unit to support the vehicle’s 12 volt systems. An additional clutch supplied by AP Racing is packaged inside the motor and connects the IC engine to the traction motor.
OTHER FEATURES
The CVT has replaced the conventional transmission and a modified bell housing accommodates the electric traction motor, while the battery pack is a Cobasys Series 1000, NiMH, 30kW 144V module that incorporates an integrated cooling system. This traction battery pack is securely mounted on the boot floor, displacing approximately 47 litres of luggage space. A sophisticated bespoke Lotus Engineering control system was developed to implement the energy management function.
To maintain the integrity of the braking circuit when the petrol engine is off, a Mes-Dea electric vacuum pump maintains the vacuum assist for the brakes. Additionally, an off-the-shelf TRW electro-hydraulic power assisted steering pump has been fitted. On the interiors, the instrument panel incorporates an additional LCD display developed by Lotus Engineering to show battery charge, power split between engine and motor, fuel economy and charge/discharge rate, and incorporates associated warning indicators where appropriate.