BMW shows future drive technologies; 2 Series PHEV prototype, direct water injection in 3-cyl. engine, and fuel cell eDrive
During a driving event at the Miramas proving grounds in southern France, BMW presented future drive technologies, including the prototype of a BMW 2 Series Active Tourer with plug-in hybrid drive. This application of BMW eDrive technologies features the first PHEV system with a front/transverse-mounted combustion engine, high-voltage generator and road-linked all-wheel drive via an electric drive system at the rear axle.
The company also showcased the use of direct water injection to enhance the efficiency of combustion engines at higher performance levels while also significantly reducing fuel consumption and emissions in key driving cycles. Finally, BMW showcased a hydrogen fuel cell drive system as a future-focused variant of BMW eDrive (teased in a technical session during April’s SAE World Congress in Detroit) enabling all-electric driving with a high operating range and short refueling times. (BMW is collaborating with Toyota on fuel cell systems. Earlier post.)
|BMW Group, Innovation Days Efficient Dynamics 2015: Hydrogen Fuel Cell eDrive Technology.|
BMW 2 Series Active Tourer plug-in hybrid prototype. The BMW eDrive technology initially developed for BMW i cars offers an extraordinary degree of freedom that allows it to be used across a broad range of vehicle concepts and segments. In the prototype of a BMW 2 Series Active Tourer with plug-in hybrid system, the front wheels are driven by a three-cylinder gasoline engine and the rear wheels by an electric motor. The result is road-linked all-wheel drive—similar to that offered by the BMW i8 plug-in hybrid sports car, albeit with the positions of motor and engine reversed.
The BMW 2 Series Active Tourer plug-in hybrid thereby serves to widen the reach of BMW eDrive in the Sports Activity Tourer segment. The BMW X5 xDrive40e—the brand’s first plug-in hybrid model—is due to be launched very shortly. (Earlier post.) The BMW 3 Series plug-in hybrid was presented as a prototype at last year’s Innovation Days event. (Earlier post.) Further models with plug-in hybrid technology are set to follow in the core model series.
|BMW 2 Series Active Tourer Plug-in Hybrid Prototype (eDrive).|
In the plug-in hybrid models developed to date by the BMW Group, the combustion engine and electric motor are combined with one another in a specific configuration for the model at hand. The signature qualities of BMW eDrive are present in all models:
Efficiency: a substantial reduction in fuel consumption and emissions over conventionally powered models, while delivering comparable performance and greater power.
Electric mobility: all-electric driving with zero local emissions in urban driving situations or when commuting.
Driving dynamics: instantaneous power delivery thanks to a boost effect from the electric motor that assists the engine under high loads.
Flexibility: the high-voltage battery can be recharged from conventional domestic power sockets, the BMW i Wallbox or at public charging stations.
Unrestricted long-distance capability: intelligent drivetrain management governs the interaction between electric motor and engine with no loss of range.
The BMW 2 Series Active Tourer plug-in hybrid prototype fuses BMW eDrive with a model-specific form of power transmission based on the front-drive concept of the standard BMW 2 Series Active Tourer. Following on from the four-cylinder gasoline engine in the BMW 3 Series plug-in hybrid prototype, a front-mounted transverse three-cylinder gasoline unit from the new Efficient Dynamics engine family now is part of a plug-in hybrid system for the first time.
|Top: full powertrain. Bottom right: front engine and transmission. Rear right: motor, power electronics and battery pack. Click to enlarge.|
The 1.5-liter BMW TwinPower Turbo engine generates an output of 100 kW/136 hp together with a peak torque of 220 N·m (162 lb-ft), with power relayed to the front wheels via a six-speed Steptronic transmission. The additional high-voltage generator on the front axle fulfills three different tasks:
it boosts the combustion engine for brief periods with extra output of up to 15 kW and some 150 N·m (111 lb-ft) from rest;
generates electric power while on the move (which is fed directly to the high-voltage battery); and
enables the engine to be started and turned off very smoothly thanks to its higher output compared to conventional starters.
The electric motor is located above the rear axle, together with its two-speed transmission and the power electronics. It sends output of up to 65 kW/88 hp and maximum torque of 165 N·m (122 lb-ft) through the rear wheels.
The high-voltage battery is housed in a space-saving position underneath the rear seat bench. The power electronics, including the charging generator, can be found next to the electric motor above the rear axle.
The on-demand, road-linked all-wheel system distributing drive to the front wheels, rear wheels or all four wheels as required. As with the BMW i8, the intelligent drivetrain management and networking with the DSC (Dynamic Stability Control) system ensure safe and assured handling characteristics together with optimized traction, dynamic acceleration and cornering, and efficiency.
The BMW 2 Series Active Tourer plug-in hybrid prototype accelerates from 0 to 100 km/h in around 6.5 seconds. Its average fuel consumption in the EU test cycle for plug-in hybrid vehicles will be approximately two liters per 100 kilometers (118 mpg US), which equates to CO2 emissions of less than 50 grams per kilometer. The range on electric power alone as measured in the EU test cycle will be 38 kilometers (24 miles).
BMW has yet to finalize pricing for the production version of the BMW 2 Series Active Tourer with plug-in hybrid drive. However, the company said, prices at launch will be in the range of existing engine variants with comparable power outputs—just as they are for the electrified versions of the BMW X5 and BMW 3 Series.
The BMW 2 Series Active Tourer plug-in hybrid prototype comes with the same Driving Experience Control switch found in the conventionally powered model variants. The Comfort and Sport settings and Eco Pro mode can be activated at the push of a button. Not only does this influence the accelerator mapping and chassis functions, it also alters the shift characteristics of the Steptronic transmission. With Eco Pro mode engaged, drivers can also make use of the coasting function, while energy efficiency is further boosted by precisely gauged power control for electrically operated convenience functions, such as the air conditioning, seat heating and heated mirrors.
The driver is able to adjust the responses of the drivetrain management using the eDrive button on the centre console. There is a choice of three settings:
Auto eDrive: this hybrid mode is activated as the default setting in Comfort mode every time the vehicle is started. Under normal loads, the vehicle initially sets off purely on electric power. Once the speed exceeds approximately 80 km/h (50 mph) or under strong acceleration, the engine cuts in automatically. When route guidance is activated, the system automatically calculates how to make the most efficient use of the energy generated by the electric motor and combustion engine, with all-electric driving prioritized over sections of the route where it makes most sense. In Comfort mode, the high-voltage battery is automatically recharged by the high-voltage generator to a charge up of around 15%.
Max eDrive: in this setting, the vehicle is powered by the electric motor alone. Top speed is limited to around 130 km/h (81 mph), while the all-electric range is some 38 kilometres. Accelerator kickdown brings the combustion engine into play.
Save Battery: This mode allows the energy stored in the high-voltage battery to be deliberately kept at a constant level or increased again up to 50% (when its charge drops below that mark) by efficiently raising the engine’s load points and using energy recuperation. The stored energy can then be used for all-electric driving at a later stage in the journey, for example when driving through an urban area.
When Sport mode is selected with the Driving Experience Control switch, on the other hand, the combustion engine and electric motor operate in unison and are geared toward a sporty driving style. The high-voltage generator provides a boost effect at low engine revs and generates electricity that is stored directly in the high-voltage battery up to a charge level of around 50%.
Drivers can call on another special feature when they require a particularly strong hit of power, e.g. for a short-notice overtaking maneuver; moving the transmission’s selector lever into the S gate has the effect of activating both power units, meaning that the drive system’s maximum output is instantly on tap. At the same time, by contrast with Sport mode the high-voltage battery can be charged to 80% using this method.
The Driving Experience Control switch modes and the eDrive button settings can be combined in different ways. This gives the driver a significant amount of scope for varying the drivetrain management and vehicle set-up to suit individual preferences.
The BMW 2 Series Active Tourer plug-in hybrid prototype also comes with a hybrid-specific energy management function built into the navigation system, which allows it to incorporate route topography, speed restrictions and the traffic situation, along with the high-voltage battery'’s available energy capacity, into drivetrain management.
Direct water injection. The precisely controlled injection of water into engine cylinders produces a cooling effect that boosts power and torque, particularly when operating at or near full throttle, while at the same time reducing fuel consumption and emissions.
|Bosch and water injection|
|Bosch is developing a water injection (WI) system for spark ignition engines in partnership with a pilot customer, said Dr. Rolf Bulander, member of the board of management of Robert Bosch GmbH and chairman of the Mobility Solutions business sector, in his talk on powertrain optimization at the 2015 Vienna Motor Symposium. (Earlier post.|
Water injection made its debut in a modern-day BMW Group engine under the hood of the BMW M4 MotoGP Safety Car. Designed by BMW M GmbH—on the basis of the M4—for use in the world’s top motorcycle racing series, it is powered by a modified version of the high-revving M TwinPower Turbo six-cylinder in-line engine that already develops maximum output of 317 kW/431 hp and peak torque of 550 N·m/405 lb-ft (combined fuel consumption: 8.8–8.3 l/100 km/26.7-28.3 mpg US; combined CO2 emissions: 204–194 g/km) in the standard BMW M4. Water injection provides the BMW M4 MotoGP Safety Car with extra power, torque and efficiency for its duties on the race track.
The BMW Group Innovation Days 2015 event marked the first presentation of this technology in a prototype of a model from the BMW core brand powered by a latest-generation three-cylinder gasoline engine.
In this version of the system, most of the water is injected directly into the combustion chamber, rather than just into the intake manifold. In the prototype, which is based on a 5-door BMW 1 Series model, direct water injection offers an optimized balance between driving pleasure and fuel consumption.
|Prototype direct water injection system for the 3-cylinder. Click to enlarge.|
Direct water injection allows the potential of turbocharging to be harnessed more effectively. The water is injected as a fine spray into the intake manifold plenum chamber where it evaporates, extracting energy from its surroundings and reducing combustion temperatures in the engine by around 25 °C.
Particularly at full throttle, this cooling effect provides a big improvement in efficiency, while helping to improve the combustion process in various other ways as well:
Efficiency: the cooling effect provided by water injection reduces temperatures sufficiently to avoid any need to inject additional fuel when operating at or near full throttle; the homogenous fuel/air mixture and improved full-load efficiency allow real-world fuel economy to be improved by up to 8%.
Emissions: reduced combustion temperatures lead to lower emissions.
Reduced knock: lower temperatures reduce the risk of uncontrolled combustion (knock).
Higher compression ratio: the reduced knock risk allows the compression ratio of the prototype model’s three-cylinder engine to be increased from 9.5:1 to 11.0:1, optimizing efficiency in the low and medium throttle range too.
Performance: the earlier ignition point and higher boost pressure improve engine power and torque by up to 10%; the increased oxygen content of the cool induction air boosts power, too.
Fuel compatibility: power output is optimized even when operating on low-octane fuel (RON 95); turbocharged engines with direct water injection can therefore be used anywhere in the world.
Thermal load reduction: the cooling effect reduces the thermal load on pistons, valves, catalytic converter and turbocharger.
The benefits of direct water injection cooling can be utilized in various ways. Depending on vehicle type and engine, it is possible to prioritize either increased power or enhanced fuel economy.
The water injection system in the BMW M4 MotoGP Safety Car draws water from a five-liter tank in the trunk. Under grueling race conditions, when the vehicle spends a lot of time operating at full throttle, the water tank is topped up every time the vehicle is refueled.
By contrast, the direct water injection system destined for future production models that is being presented at the BMW Innovation Days never requires topping up in everyday use. Unless the vehicle is operated in exceptional climatic conditions, the system is fully self-replenishing, thanks to on-board water recovery.
The water supply for water injection cooling is kept topped up by the continuous recovery of condensed water from the air conditioning system. Every time the engine is switched off, all the water in the hose system is drained into the tank. This guards against system components icing up in sub-zero temperatures and prevents engine corrosion. The water tank itself is also located in a frost-protected position in the vehicle.
|In addition to the 5 Series fuel cell demonstrator, BMW also showcased an i8-based hydrogen fuel cell vehicle. Click to enlarge.|
Hydrogen fuel cell drive. As part of its research and pre-development work in the area of drive technology, the BMW Group has focused on the use of hydrogen as an energy source for more than 30 years. In 2006 the first luxury sedan for everyday use to be powered by a hydrogen combustion engine was unveiled—the BMW Hydrogen 7. (Earlier post.)
More than 15 years ago, the BMW Group also began to direct its spotlight onto hydrogen fuel cell drive systems. Advances in energy efficiency, performance capability and everyday practicality have likewise been made with this technology.
The demonstration vehicle is based on a BMW 5 Series Gran Turismo. Key features are as follows:
Electric motor developing 180 kW/245 hp, power electronics and high-voltage battery for interim energy storage; developed as a variant of BMW eDrive technology for BMW i cars and BMW brand plug-in hybrid models.
Hydrogen storage in the form of a tunnel tank between the front and rear axle; industry standard 700 bar CGH2 vessel technology and cryogenic pressure vessel technology (CCH2) patented by the BMW Group for storing gaseous hydrogen at low temperature and 350 bar pressure; operating range: over 500 kilometres (more than 300 miles).
Cutaway of hydrogen tunnel tank. Click to enlarge.
Fuel cells, housing and ancillary systems: initial results from the collaboration between the BMW Group and the Toyota Motor Corporation on Fuel Cell Electric Vehicle (FCEV) technology.
|Top left: fuel cell components. Top right: stack assembly. Bottom left and right: fuel cell system. Click to enlarge.|
BMW said that its strategic collaboration with Toyota Motor Company has provided fresh momentum for the development of FCEV drive technology. The aim of the collaboration is to have an initial group of approved components ready by 2020.
The successful introduction of FCEVs is dependent on the development of a hydrogen infrastructure in the markets concerned. The two collaboration partners are supporting this process through jointly created technological standards which make fuel cell-powered vehicles easier to use and help to increase their reach and numbers.
The operating range of the prototype is more than 500 km (300 miles).
BMW said that its aim is to establish hydrogen fuel cell drive technology as an integral element of the BMW Group’s Efficient Dynamics strategy for the long term. This would create a drive system portfolio of the greatest possible variety, which can be adapted flexibly to different vehicle concepts, customer desires and legal requirements around the world:
Highly efficient combustion engines with BMW TwinPower Turbo technology.
Intelligently controlled plug-in hybrid systems with BMW eDrive or Power eDrive technology enable low-emission electric driving very much in the BMW mould.
Locally emission-free, battery-electric vehicles with a high-voltage battery like that of the BMW i3.
Fuel Cell Electric Vehicle (FCEV) with hydrogen fuel cell technology and BMW eDrive electric drive system.