Expansion and co-location for Lotus in the USA

The introduction of the Lotus Evora 400, as a 2017 North American Model Year, marks the start of a fresh period in Lotus’ presence in this vital market. The previous model Evora already received positive acclaim from media, customers and dealers alike and reaffirmed Lotus as the maker of some of the finest, purest, most lightweight and most efficient sports cars sold today.

Jean-Marc Gales, Chief Executive Officer, Group Lotus plc, explains: “The Lotus Evora 400 combines high performance with the legendary Lotus benchmark handling. It is lighter, more efficient and dynamically better than ever. It is the perfect high performance machine for those discerning buyers seeking a hand built British-built sports car that possesses a purer driving experience, greater agility and a more involving drive.”

To coincide with the introduction of the Lotus Evora 400 into the North American market, the company has expanded its dealer network to 47 outlets, with the introduction of four new dealers in both West Covina and Thermal (in California), Scottsdale (Arizona) and Calgary (Alberta), with exciting growth planned for the near future.

In addition, and in the most significant change in Lotus’ presence in the USA for many years, Lotus Cars USA. Inc, (LCU), based currently in Lawrenceville, Georgia, will co-locate to Lotus Engineering. Inc, (LEI) in Ann Arbor, Michigan, the heart of the US motor industry. This will ensure that both divisions can grow their individual operations, while benefiting from improved efficiency through sharing a number of business functions. This co-location is expected to be completed by the end of July 2015.

Jean-Marc Gales continued: “North America, as the largest sports car market in the world, is important for Lotus, both for model sales and for our engineering consultancy business. By having both of our USA organisations located in Michigan, we shall be within the heartland of the USA automotive sector, where the headquarters of some of the most important, influential and significant automotive manufacturers and suppliers are based. This will reaffirm our presence in the North American market, by providing improved customer service, better technical and consultancy support, while ensuring that we have access to a skills base not found anywhere else in the territory. All of this fits with Lotus developing speedily in North America in years to come.”

The Lotus Evora 400, unveiled at the Geneva Show in March 2015, has already generated excitement worldwide. With 400 hp, an acceleration to 60 mph in 4.1 seconds and a maximum speed of 186mph, the Lotus Evora 400 is six seconds quicker around the company’s Hethel test track than the previous Evora S.

Lotus Engineering adds lightness to a Crossover Utility Vehicle

California Air Resources Board (CARB) publishes results of Lotus Engineering’s vehicle mass reduction study on a Crossover Utility Vehicle (CUV)

  • Results show a total vehicle mass reduction of 31% (528.3 kg or 1,162 lbs.) and a $239 (£150 / €188) saving in overall vehicle cost.
  • Body structure utilises advanced materials including high-strength steels, aluminium, magnesium and composites along with high tech joining and bonding techniques.

Following on from Lotus’ successful “Phase One” study, published in 2010, which looked at the empirical and theoretical weight saving for a standard CUV, Lotus Engineering conducted further research to confirm if a lightweight and commercially feasible body structure has the potential to meet or exceed the requirements for size, luggage volume, comfort, crashworthiness and structural integrity.

Lotus Engineering’s “Phase Two” body structure design was based on the dimensions of a 2009 Toyota Venza CUV and utilised advanced materials such as high-strength steels, aluminium, magnesium and composites along with advanced joining and bonding techniques to achieve a substantial body and overall vehicle mass reduction without degrading size, practicality or performance. The body mass was reduced by 37% (311 lbs. or 141.6 kg), which contributed to a total vehicle mass reduction of 31% (1,162 lbs. or 528.3 kg) including the mass savings of other vehicle systems (interior, suspension, chassis, closures, etc.) that had previously been identified in “Phase One”.

The detailed Computer Aided Engineering (CAE) analysis undertaken indicated that a 31% mass-reduced vehicle with a 37% lighter Body-in-White (BIW) structure has the potential to meet U.S. Federal impact requirements. This includes side impact and door beam intrusion, seatbelt loading, child seat tether loadings, front and rear chassis frame load buckling stability, full frontal crash stiffness and body compatibility and frame performance under low-speed bumper impact loads as defined by the Insurance Institute for Highway Safety (IIHS). The result is a BIW design with a 20% increase in torsional stiffness over the class leading CUV.

Although the significant mass savings in the BIW design results in an increased BIW cost of $723 (£456 / €568), the overall vehicle cost is reduced through savings of $239 (£150 / €188) identified across the whole vehicle and when manufacturing and assembly costs are included in the analysis. A significant reduction in the parts count from 269 to 169, achieved by an increased level of component integration, also helped offset the increased BIW piece cost.

The background to the study

In April 2010, Lotus Engineering concluded the first phase of a study which substantiated that a reduction in vehicle mass could be achieved for medium production volume vehicles (approximately 50,000 units per year) with a 23% reduction in fuel consumption. In September 2010 the California Air Resources Board (CARB) commissioned Lotus Engineering to initiate Phase Two of the study and take a deeper look into the future of lighter, more efficient vehicles manufactured using lighter yet stronger materials.

Lotus has always been about Lightweight

When Lotus founder Colin Chapman coined the phrase “performance through light weight” he was referring to much more than mere accelerative performance. In the broader sense he meant that a lighter vehicle does everything better, including being more fuel efficient. Over the past 60-plus years, Lotus road and racing vehicles have consistently benefited from this core philosophy and Lotus has developed a strong reputation as a leader in lightweight vehicle technologies.

After decades of most manufacturers building increasingly heavy, feature-laden cars, now the very aggressive corporate average fuel economy (CAFÉ) standards increasing from a target of 35.5 mpg in 2016 to 54.5 in 2025 have all manufacturers reevaluating the virtues of mass reduction and prioritising the materials, technologies and production methods that will enable lighter, stronger and more efficient vehicles.

Lotus Engineering develops Electric Drivetrain for the Rolls-Royce 102EX

Lotus Engineering, a company with over 20 years of EV and HEV experience, has been responsible for all aspects of the electric drivetrain integration for 102EX, the Rolls-Royce Phantom Experimental Electric. This includes the largest battery pack fitted to a road car, together with an innovative 7 kW induction charging system. These components and the electric drivetrain have been integrated by Lotus Engineering into the existing Phantom electrical systems, giving an efficient electrical propulsion control strategy and retaining full vehicle functionality.

Lotus Engineering has a broad expertise in vehicle design, manufacture and development. For the Phantom Experimental Electric project Lotus Engineering provided engineering services in the areas of: drivetrain layout, vehicle simulation, Computer Aided Engineering (CAE), component specification, vehicle build, control strategy, control integration, procurement, commissioning and development testing. This project highlights the technical competence in Electrical and Electronic Integration and the capability and range of consultancy services offered by Lotus Engineering.

The Phantom Experimental Electric has two electric motors to replace the 6.75 litre V12 engine. These electric motors each produce 145 kW of power to provide a total 290 kW and torque of 800 Nm giving a 0 – 100 km/h time of under eight seconds and a top speed limited to 160 km/h.

In the conversion of a Phantom into an electric vehicle a study was conducted to ensure that the optimum layout of the electric drivetrain and ancillaries was achieved with no intrusion into passenger compartment. Following an iterative design study the 71 kWh, 640 kg lithium ion battery pack was placed under the bonnet where the engine had been. The two motors, gearbox and inverters were located behind the rear seats in the original fuel tank bay, with power cables running longitudinally between the converters and the battery. This has enabled the Phantom Experimental Electric to retain its 50:50 weight distribution and characteristic Rolls-Royce driving experience.

The Rolls-Royce Phantom is a complex vehicle with many advanced electrical systems. The integration of the electric drivetrain and ancillaries with the existing vehicle control unit provided the greatest challenge for the project. To compound this the Phantom Experimental Electric features the additional complexity of a 3 mode charging system (single phase, three phase and the inductive power transfer) together with a two level driver selectable regenerative braking system.

Dr Robert Hentschel, Director of Lotus Engineering, said “The Rolls-Royce Phantom Experimental Electric is an extremely advanced vehicle. I am delighted that Rolls-Royce Motor Cars has recognised Lotus Engineering’s world class engineering capability and chosen us to be a part of this project. We have taken a great deal of pride working for such a prestigious ultra luxury brand and I believe that this project illustrates the technical competency of Lotus Engineering in Electrical and Electronic Integration and the capability to apply our expertise to a wide range of applications and types of vehicle”.

[press release from Lotus Engineering]

Lotus Engineering wins CARB contract

2020 Toyota Venza

Lotus Engineering is delighted to announce that it has been commissioned by the Air Resources Board of California to undertake the second stage of a study investigating efficient, lightweight vehicles manufactured using lighter, stronger materials.

Lotus Engineering will conduct a detailed structural design and analysis of the prototype vehicle from an earlier study to demonstrate it meets the crashworthiness and stringent safety requirements for vehicles sold in the United States.

In April this year, Lotus Engineering concluded the first part of the study, released by the International Council on Clean Transportation in California, which recognised that a reduction in vehicle mass of 38% can be achieved for medium volume vehicles (around 50,000 units a year) with just an increase in 3% in vehicle cost and giving a 23% reduction in fuel consumption.

It is widely recognised in the automotive industry that a reduction in vehicle mass gives more efficient vehicles; with the global drive to reduce emissions, manufacturers are working hard to take mass out their cars. Lightweight vehicles have additional benefits in terms of performance, agility and cornering, (the lighter the car, the less power it needs to propel it along the road for the same performance as a heavier car).

For 62 years, Lotus has been leading the car world with ‘performance through light weight’ engineering. The strict adherence to this philosophy enabled Lotus to develop some of the finest sportscars of all time such as the Lotus Elite, Elan, Esprit from Lotus’ peerless past and the Elise, Exige and Evora from the current line up – all of which are the lightest cars in their class. But it is not just sportscars; Lotus’ consultancy division, Lotus Engineering has been applying its light weight principles behind the scenes for other car makers for years on many types of vehicles, both low volume and mass production.

This study will be led by Lotus Engineering’s Michigan, USA office with completion in April 2011. The vehicle design will use a mixture of materials best suited to its application including aluminium, magnesium, composites, high strength lightweight steel and plastics.

Lotus Lightens a Toyota Venza

2020 Toyota Venza

Lotus Engineering has conducted a study to develop a commercially viable mass reduction strategy for mainstream passenger vehicles. This study, released by the International Council on Clean Transportation, focused on the use of lightweight materials and efficient design and demonstrated substantial mass savings. When compared with a benchmark Toyota Venza crossover utility vehicle, a 38% reduction in vehicle mass, excluding powertrain, can be achieved for only a 3% increase in component costs using engineering techniques and technologies viable for mainstream production programmes by 2020. The 2020 vehicle architecture utilises a mix of stronger and lighter weight materials, a high degree of component integration and advanced joining and assembly methodologies.

Based on U.S. Department of Energy estimates, a total vehicle mass reduction of 33% including powertrain, as demonstrated on the 2020 passenger car model, results in a 23% reduction in fuel consumption. This study highlights how automotive manufacturers can adopt the Lotus philosophy of performance through light weight.

Dr Robert Hentschel, Director of Lotus Engineering said: “Lighter vehicles are cleaner and more efficient. That philosophy has always been core to Lotus’ approach to vehicle engineering and is now more relevant than ever. Lightweight Architectures and Efficient Performance are just two of our core competencies and we are delighted to have completed this study with input from the National Highway Traffic Safety Administration and the U.S. Environmental Protection Agency to provide direction for future CO2 reductions. We believe that this approach will be commonplace in the industry for the future design of vehicles.”

The study investigated scenarios for two distinct vehicle architectures appropriate for production in 2017 and 2020. The near-term scenario is based on applying industry leading mass reducing technologies, improved materials and component integration and would be assembled using existing facilities. The mass reduction for this nearer term vehicle, excluding powertrain, is 21% with an estimated cost saving of 2%.

A benchmark Toyota Venza was disassembled, analysed and weighed to develop a bill of materials and understand component masses. In developing the two low mass concepts, Lotus Engineering employed a total vehicle mass reduction strategy utilising efficient design, component integration, materials selection, manufacturing and assembly. All key interior and exterior dimensions and volumes were retained for both models and the vehicles were packaged to accommodate key safety and structural dimensional and quality targets. The new vehicles retain the vision, sight line, comfort and occupant package of the benchmarked Toyota Venza.

Darren Somerset, Chief Executive Officer of Lotus Engineering Incorporated, Lotus’ North American engineering division which led the study, said “A highly efficient total vehicle system level architecture was achieved by developing well integrated sub-systems and components, innovative use of materials and process and the application of advanced analytical techniques. Lotus Engineering is at the forefront of the automotive industry’s drive for the reduction in CO2 and other greenhouse gas emissions and this study showcases Lotus Engineering’s expertise and outlines a clear roadmap to cost effective mass efficient vehicle technologies.”

Mass and Cost Summary

Base Toyota Venza

excluding powertrain

Lotus Engineering Design

System

Weight

(kg)

2020 Venza

2017 Venza

% Mass Reduction

% Cost Factor

% Mass Reduction

% Cost Factor

Body

383

42%

135%

15%

98%

Closures/Fenders

143

41%

76%

25%

102%

Bumpers

18.0

11%

103%

11%

103%

Thermal

9.25

0%

100%

0%

100%

Electrical

23.6

36%

96%

29%

95%

Interior

252

39%

96%

27%

97%

Lighting

9.90

0%

100%

0%

100%

Suspension/Chassis

379

43%

95%

26%

100%

Glazing

43.7

0%

100%

0%

100%

Misc.

30.1

24%

99%

24%

99%

Totals

1290

38%

103%

21%

98%

The 2020 Passenger Car Technical Details

Body

The body includes the floor and underbody, dash panel assembly, front structure, body sides and roof assembly. The baseline Toyota Venza body-in-white contained over 400 parts and the revised 2020 model reduced that part count to 211. The body-in-white materials used in the baseline Venza were 100% steel, while the 2020 model used 37% aluminium, 30% magnesium, 21% composites and 7% high strength steel. This reduces the structure mass by 42% from 382 kg to 221 kg.

The low mass 2020 body-in-white would be constructed using a low energy joining process proven on high speed trains; this process is already used on some low volume automotive applications. This low energy, low heat friction stir welding process would be used in combination with adhesive bonding, a technique already proven on Lotus production sports cars. In this instance, the robotically controlled welding and adhesive bonding process would be combined with programmable robotic fixturing, a versatile process which can be used to construct small and large vehicles using the same equipment.

Closures/Fenders

The closures include all hinged exterior elements, for example, the front and rear doors and the rear liftgate. One alternative approach included fixing the primary boot section to improve the structure, reduce masses and limit exposure to high voltage systems. A lightweight access door was provided for checking and replacing fluids.

The closures on the baseline Toyota Venza were made up of 100% steel. The low mass Venza closures/fenders would be made up of 33% magnesium, 21% plastic, 18% steel, 6% aluminium with the other 22% consisting of multiple materials. The mass savings are 41%, a reduction from 143 kg to 84 kg.

Interior

The interior systems consist of the instrument panel, seats, soft and hard trim, carpeting, climate control hardware, audio, navigation and communication electronics, vehicle control elements and restraint systems. There is a high level of component integration and electronic interfaces replace mechanical controls on the low mass model. For the 2020 model the instrument panel is eliminated replaced by driver and passenger side modules containing all key functional and safety hardware. A low mass trim panel made from a high quality aerated plastic closes out the two modules. The air conditioning module is incorporated into the console eliminating the need for close out trim panels; heated and cooled cupholders are integrated into the HVA/C module. The audio/HVA/C/Navigation touch screen contains the shifter and parking brake functions and interfaces with small electric solenoids. This eliminates conventional steel parking brake and shifter controls and cables as well as freeing up interior space.

The front seats mount to the structural sill and tunnel structure eliminating conventional seat mounting brackets (10 kg) and the need to locally reinforce the floorpan. The composite front seat structure utilises proven foam technology; the seat mass is reduced by up to 50%. The rear seat support structure is moulded into the composite floorpan eliminating the need for a separate steel support structure. The front and rear seats use a knit to shape fabric that eliminates material scrap and offers customers the opportunity to order their favourite patterns for their new vehicle. Four removable carpet modules replace the traditional full floor carpeting; this reduces mass and allows cost effective upgrading of the carpet quality. The floorpan is grained in all visible areas. The 2017 production interior mass was reduced from 250 kg to 182 kg with projected cost savings of 3%. The 2020 production interior mass was 153 kg with projected cost savings of 4%.

Chassis/Suspension

The chassis and suspension system was composed of suspension support cradles, control links, springs, shock absorbers, bushings, stabilizer bars and links, steering knuckles, brakes, steering gearbox, bearings, hydraulic systems, wheels, tires, jack and steering column.

The chassis and suspension components were downsized based on the revised vehicle curb weight, maintaining the baseline carrying capacity and incorporating the mass of the hybrid drive system.

The total vehicle curb weight reduction for the 2020 vehicle was 38%, excluding the powertrain. Based on the gross vehicle weight, which includes retaining the baseline cargo capacity of 549 kg and utilising a hybrid powertrain, the chassis and the suspension components were reduced in mass by 43%, with projected cost savings of 5%.

Front and Rear Bumpers

The materials used on the front and rear bumpers were very similar to the existing model to maintain the current level of performance. One change was to replace the front steel beam with an aluminium beam which reduced mass by 11%. The use of a magnesium beam was analysed but at the current time exceeded the allowable price factor.

Heating, Ventilation and Air Conditioning

The air conditioning system was integrated into a passenger compartment system and an engine compartment system. This section addressed the under hood components which included the compressor, condenser and related plumbing. The under hood components were investigated for technologies and mass.

The study showed a relatively small mass difference for the underhood air conditioning components based on both vehicle mass and interior volume. Because of the highly evolved nature of these components, the requirements for equivalent air conditioning performance and the lack of a clear consensus for a future automotive refrigerant, the mass and cost of the Toyota Venza compressor, condenser and associated plumbing were left unchanged for both the 2017 and 2020 models.

Glazing

The glazing of the baseline vehicle was classified into two groups: fixed and moving. The fixed glass is bonded into position using industry standard adhesives and was classified into two sub groups: wiped and non wiped.

Factors involved in making decisions about glazing materials include the level of abrasion it is likely to see during the vehicle life, the legislative requirements for light transmissibility, the legislative requirements for passenger retention and the contribution it will make to interior noise abatement.

The specific gravity of glass is 2.6 and the thickness of a windshield is usually between 4.5 mm and 5 mm, therefore the mass per square metre of 5 mm glass is approximately 13 kgs. The high mass of glass provides a strong incentive to reduce the glazed area of the body, reduce the thickness of the glass and find a suitable substitute that is lighter. Fixed glass on the side of the vehicle offers the best opportunity for mass reduction.

The mass of the baseline glazing was retained for both the 2017 and 2020 models; this was a conservative approach. It is possible that coated polycarbonate materials may become mainstream in the 2017 – 2020 timeframe for fixed applications.

Electrical/Lighting

The estimated mass savings for using thinwall cladding and copper clad aluminium wiring, as used on the 2017 model was 36% versus the baseline model. The lighting technologies section reviewed included diodes, xenon and halogen. The study also reviewed a variety of wireless technologies under development for non-transportation applications that could be used in this time period pending successful development for mobile applications.

More information
The full report, entitled ‘An Assessment of Mass Reduction Opportunities for a 2017 – 2020 Model Year Vehicle Program’ can be found at this link (pdf).

[press release from Lotus Engineering]

Lotus hybrid power for the PROTON Concept

The PROTON Concept car, to be unveiled at the Geneva Motor Show, showcases an advanced series hybrid drivetrain, designed and developed by Lotus Engineering.

PROTON Concept Drivetrain

Lotus Engineering, the world-renowned automotive consultancy division of Lotus Cars Limited today announces its latest series hybrid vehicle technology application in the PROTON Concept, which will be unveiled at the 80th International Geneva Motor Show. The complete hybrid drivetrain in the PROTON Concept city car has been developed by Lotus Engineering and it includes the Lotus Range Extender engine, designed specifically for series hybrid vehicles.

The PROTON Concept, a plug-in series hybrid city car, has been styled by Italdesign and will be unveiled on the Italdesign stand at the Geneva Motor Show. Lotus Engineering has designed and integrated the complete drivetrain, including the electrical drive system with single-speed transmission, which delivers low emissions, optimised performance and acceptable electric-only operating range for city use. For longer journeys, when the battery charge level falls, the 3 cylinder, 1.2 litre Lotus Range Extender engine is used to replenish the charge in the battery and provide electrical power for the drive motors. The battery can also be recharged via an AC mains domestic outlet to achieve initial electric-only operation.

Dr Robert Hentschel, Director of Lotus Engineering said: “The hybrid drivetrain of the PROTON Concept is another example of Lotus Engineering’s expertise in electrical and electronic systems and efficient performance engines. The high efficiency Lotus Range Extender engine, which we unveiled to great acclaim at the IAA Frankfurt Motor Show last year is perfectly suited for the advanced series hybrid we have created for the PROTON Concept city car. It is an exciting example of the diverse range of highly efficient total propulsion systems that Lotus Engineering continues to develop for its partners and clients.”

PROTON Holdings Berhad Group Managing Director, Dato’ Haji Syed Zainal Abidin Syed Mohd Tahir said, “Our collaboration with Lotus and Italdesign on progressive technology and design will further propel our competitiveness in the world market. Through this association, we strive to acquire and jointly develop new knowledge, skills and technologies that will ultimately benefit our customers.”

[press release from Lotus]

Lotus Omnivore Engine interactive animation

Picture 1

While we have posted about the Lotus Omnivore engine before, all the existing information on it has been from dry technical press releases. Lotus Engineering has just released a new interactive animation that allows you to play with the various parameters of the engine and see how it alters itself to deal with various fuel mixes, loads, speeds, etc… My personal favorite is the Variable Combustion Ratio (VCR) that physically alters the volume of the combustion chamber.

Click here to play with the animation.

New executive at Lotus Cars

Press release from Lotus:

A new decade begins with considerable changes at Group Lotus and CEO Dany Bahar is strengthening his executive team in order to take the Lotus brand to the next phase of its evolution and realise his ambitious plans for 2010 and beyond.

Paul Newsome

Lotus is pleased to announce Paul Newsome’s appointment to Director of Product Engineering for Lotus Cars. Currently Managing Director of Lotus Engineering, Paul becomes Director of Product Engineering, responsible for the engineering behind all future Lotus cars and for ensuring that they drive and perform in the way that only a Lotus can.

On taking up the challenge of Director of Product Engineering, Paul Newsome said, “Lotus has, through its launch of the all new multi-award winning Lotus Evora, again demonstrated the capability of its engineering. I look forward to building on this tremendous success with the team and delivering the exciting next generation of products we have planned. These will continue to demonstrate Lotus’ world leading attributes of performance and dynamics through light weight and take the Lotus brand into more segments of the sports car market.”

Dany Bahar commented, “This year will see some very exciting developments to the Lotus product line-up and I have set the Lotus workforce quite a challenge! The success of the changes that I and my executive team look to make relies upon their support and I thank them for their dedication and commitment in joining us on this journey.

“The executive team I am building around me represent some of the industry’s most innovative and passionate professionals and I look forward to working with Paul and the rest of the team to make Lotus the brand it has the potential to be.”

New appointment and contracts at Lotus Engineering

Press release from Lotus Engineering

Lotus Engineering starts the New Year strongly, announcing significant new contracts and welcoming a new Director of Lotus Engineering.
Robert Hentschel

Major new projects with three Chinese clients ensure an excellent start to 2010 for Lotus Engineering, the automotive consultancy and technology division of Lotus Cars Limited. These projects result in a fourth consecutive year of growth in new orders for Lotus Engineering’s global third party consultancy work, with a quarter of the financial year still to go.

To continue to build on the success of both the Lotus Engineering and Lotus Cars divisions, Lotus has also made changes to the senior management structure. Dr Robert Hentschel joins Lotus as Director of Lotus Engineering. Dr Hentschel’s task will be to lead the expansion of Lotus Engineering’s third party consultancy work and to further develop its position of technology leadership in lightweight architectures, driving dynamics, efficient performance and electrical/electronics. Dr Hentschel will have full responsibility for Lotus Engineering worldwide, reporting to Dany Bahar, CEO of Group Lotus plc. Dr Hentschel brings a wealth of experience from the automotive industry and engineering services sector, most recently from positions at EDAG as Chief Operating Officer for North American operations and previously as Head of the Electrical/Electronics Business Unit.

Paul Newsome, previously Managing Director of Lotus Engineering, takes up a new role as Director of Product Engineering for Lotus Cars to develop an exciting range of new Lotus cars.

Dr Hentschel commented: “This is a fantastic opportunity for me to contribute to the continued success of this outstanding business which boasts talented engineers and an iconic brand. Lotus Engineering has an exceptional heritage with an exciting array of future products, technologies and services that will further enhance its position as a pioneer in the new automotive era. Our key areas of expertise allow us to deliver exciting vehicles and sustainable transport solutions that are exactly aligned to the needs of the global automotive industry.”

Lotus Omnivore Engine – 10% Better Fuel Economy than Current Leading Gasoline Engines

Press release from Lotus

Initial phase of Omnivore development achieves 10% improvement in fuel consumption compared to stratified direct injection engines, also with ultra low emissions. The research signals a potential paradigm shift with engine ‘upsizing’ for increased fuel economy.

Lotus Omnivore Comparison Graph
The first testing phase of Lotus Engineering’s Omnivore variable compression ratio, flex-fuel direct injection two-stroke engine has been successfully completed on gasoline. In addition to exceptional fuel consumption results, the engine has successfully demonstrated homogenous charge compression ignition (HCCI) – where the engine operates without the need for the spark plug to ignite the fuel and air mixture in the cylinder – down to extremely light loads. Traditionally, this has been challenging but this combustion process results in ultra low emissions and has been achieved over a wide range of engine operating conditions, even from cold start.

The detailed research has so far focused on lower speed and load conditions that represent a major proportion of an engine’s operation in a real world environment. At 2000rpm and up to approximately 2.7 bar IMEP (Indicated Mean Effective Pressure), the ISFC (Indicated Specific Fuel Consumption) achieved is approximately 10% better than current spray-guided direct injection, spark ignition engines. Emissions results are an impressive 20 ppm NOx at less than 2.3 bar load and has four-stroke-equivalent hydrocarbons and carbon monoxide emissions.

Simon Wood, Technical Director of Lotus Engineering said: “These impressive results represent an important step-forward in Lotus Engineering’s strategy of developing an array of more efficient multi-fuel combustion systems. Omnivore lays the foundations for a novel and pragmatic vision of a variable compression ratio engine concept suitable for production. A multi-cylinder version is practical for a wide variety of vehicles and offers greatest benefit to C and D class passenger cars which can take advantage of the low cost architecture and significantly improved fuel economy and emissions. We are continuing our discussions with other manufacturers and eagerly anticipate the development of multi-cylinder demonstrations of this revolutionary engine configuration.”

The Omnivore engine concept achieves wide-range HCCI combustion and low CO2 emissions through the application of a simple wide-range variable compression ratio mechanism, itself facilitated by the adoption of the two-stroke operating cycle. Technologies combined in this package are all synergistic and provide a route to the efficient use of alternative fuels, accelerating the displacement of fossil fuels.

Jamie Turner, Chief Engineer of Powertrain Research at Lotus Engineering said: “The automotive industry, including Lotus Engineering, has quite rightly advocated engine downsizing for four-stroke engines. This is as a result of the dominance of the four-stroke cycle in the automotive world and its generation of throttling losses at part-load, where vehicles run most of the time. The two-stroke cycle, conversely, does not suffer from significant throttling losses and in many ways is a more natural fit for automotive use. With the thermodynamic disadvantages of throttling losses removed, the two-stroke engine is free to be sized according to its improved part-load fuel consumption. Downsizing therefore isn’t vital and, due to the improved light-load efficiency and emissions performance we see with Omnivore, this technology approach and ‘upsizing’ could permit a more efficient engine.”

The initial Omnivore programme has been in collaboration with Queen’s University Belfast and Orbital Corporation Limited Australia, with sponsorship from DEFRA/DECC and DOE NI through the Renewables Materials LINK programme. Future work by Lotus Engineering will concentrate on further investigating the operation on gasoline and alternative renewable fuels such as ethanol and methanol, with more in-depth analysis of specific test points.

Technical Detail
Lotus Omnivore Engine
Omnivore Summary
The Omnivore engine concept features an innovative variable compression ratio system and uses a two-stroke operating cycle with direct fuel injection. It is ideally suited to flex-fuel operation with a higher degree of optimisation than is possible with existing four-stroke engines.

The engine concept features a monoblock construction that blends the cylinder head and block together eliminating the need for a cylinder head gasket, improving durability and reducing weight. In this case, the application of a monoblock is facilitated by the absence of the requirement for poppet valves. A novel charge trapping valve in the exhaust port allows asymmetric timing of exhaust flow and continuous variation of the exhaust opening timing.

The Omnivore engine uses the Orbital FlexDI fuel injection system which produces fine in-cylinder fuel preparation irrespective of fuel type and, together with air pre-mixing, allows efficient two-stroke combustion and low-temperature starting, whilst offering singular opportunity for advanced HCCI control.

The variable compression ratio is achieved by the use of a puck at the top of the combustion chamber. This simple, yet effective system moves up and down effecting the change in geometric compression depending on the load demands on the engine.

Engine Concept Features

Monoblock
The monoblock incorporates the cylinder head, the cylinder barrel and the inlet ports, together with mounts for the variable compression ratio system and the charge trapping valve housing. It also contains the non-moving location of one of the two possible injector mounting positions provided for research purposes. The other injector position is in the variable compression ratio puck. The monoblock is mounted on the upper crankcase, which is a common component with all of Lotus’ single-cylinder research engines. The engine carries a full primary and secondary balancer system. The monoblock is water-cooled by an electric water pump.

Computational fluid dynamics is used extensively to ensure effective cooling of the monoblock, a feature assisted by the removal of the cylinder head gasket, inherent in such architecture. The chief advantage of a monoblock construction in any engine, aside from the bill of materials and assembly benefits, is the reduction of bore distortion afforded by the removal of cylinder head bolts. This is especially important in piston-ported 2-stroke engines.

Variable Compression Ratio Mechanism
The primary component of the variable compression ratio mechanism is what is termed the ‘puck’, or a moveable junk piston in the cylinder head. In the case of the research engine, this puck is driven in and out by a double-eccentric mechanism itself comprising proprietary parts. The puck itself does not move at engine speed. In addition to the spark plug, the puck carries one of two possible injector positions. It is water-cooled and carries simple piston (or ‘junk’) rings for primary sealing, and an ‘O’-ring towards the top for final sealing.

The variable compression ratio system is controlled by an electric motor and worm drive arrangement at the front of the engine. Because there are no poppet valves in the engine, it is clear that the puck could be of a large diameter and since there is no need for valve cut-outs in the piston crown, the minimum volume of the combustion chamber can be much smaller than has been the case in variable compression ratio engines shown to date. When the puck is in its innermost position, its surface is essentially coincident with that of the combustion chamber squish band and this yields the highest compression ratio of 40:1.

The combustion chamber geometry necessarily alters as the puck is moved to vary the compression ratio. The chamber geometry in Omnivore was therefore chosen on the basis of 2-stroke experience in spark ignition operation. Consequently, the puck is positioned in the cylinder head in such a way that the non-moving squish band directs cooling flow towards the spark plug. The puck is water-cooled from the main engine cooling circuit.

Charge Trapping Valve
The charge trapping valve is caused to oscillate by a short articulated connecting link from an engine-speed eccentric shaft itself rotated by a belt drive from the crankshaft. A simple charge trapping valve mechanism provides for asymmetric exhaust timing and hence a modification of the original piston-ported two-stroke operating cycle. Fitting an articulated link between the eccentric shaft and the trapping valve actuating arm affords the opportunity independently to vary the opening and/or closing point. In this ‘variable’ form, at light load, the charge trapping valve can be made to control exhaust port opening, to maximize expansion in the cylinder, and the blowdown period can be optimised. The position of the control arm is controlled by the engine management system. All charge trapping valve components and their configuration have been analysed kinematically, and since they operate with modified simple harmonic motion, they do not suffer from jerk stresses.

Other Components
The cranktrain of the engine comprises an 86 mm stroke crankshaft, a trunk piston of 86 mm bore and a connecting rod with 195.5 mm between centres. The piston carries four piston rings: two pegged half-keystone compression rings which traverse the ports in the upper section, and a Napier scraper ring and U-Flex oil control ring in separate grooves in the lower portion. These are not pegged since they do not have to traverse the ports. In this manner, the working chamber is completely sealed from the crankcase and hence wet-sump lubrication can be employed.

Since this is a research engine, it is cooled by an electric water pump with a separate electrically-driven oil pump used for lubrication. Scavenge air is provided externally. For convenience, air for the Orbital air-assist DI system is provided from the factory air supply regulated to 6.5 bar maximum air delivery pressure. Note that in any multi-cylinder application it is envisaged that all these subsystems would be incorporated into the engine in the normal manner.