- Innovative hybrid concept based on pure bioethanol
- Zero fossil CO2 emissions in all modes
- 191 kW/260 bhp Saab BioPower engine running on E100 fuel
- Increased performance with threefold torque boost from electric motors
- Fuel saving 'Zero Mode' for city driving on electric power only
- Energy saving features including regenerative braking
- Estimated fuel consumption. 7.8L/100 km, mixed driving
- Space efficient modular design uses existing vehicle architecture
- All-wheel-drive for improved traction
The innovative Saab BioPower Hybrid Concept, making its world premiere at the
Stockholm Motor Show (March 30 - April 9, 2006), delivers zero fossil CO2
emissions, enhanced performance and a range of energy-saving features by
combining the use of pure bioethanol fuel and electric power generation for the
first time. As the world's first fossil-free hybrid vehicle, the Saab 9-3
Convertible show car also becomes the world's first hybrid soft-top.
Packing formidable pulling power from its 191 kW 2.0-litre turbo BioPower
engine and 53 kW electric motor, the BioPower Hybrid Concept in the Saab 9-3 can
briefly generate torque values three times greater than its petrol-only
equivalent. It is a sporty combination that makes for improved performance, as
you would expect from Saab, as well as greater fuel economy and an extended
driving range.
Saab's modular hybrid system features a maintenance-free, 300-volt battery
bank designed to last the lifetime of the vehicle, a 38 kW rear-mounted electric
motor, a 15 kW integrated starter generator and all-wheel-drive with electric
power transmission to the rear wheels. The entire system has been packaged
without sacrificing cabin accommodation or trunk space, as demonstrated by its
unveiling in the Saab 9-3 Convertible.
The all-aluminium 2.0-litre BioPower engine is modified to run on pure E100
bioethanol fuel, giving zero fossil CO2 exhaust emissions, and operates in
tandem with the electrical power system. This offers fuel-saving stop/start
functionality, torque boosting electric power assistance on demand, an
electric-only 'Zero Mode' for city driving and regenerative braking.
The BioPower Hybrid Concept prototype car, a 9-3 sport sedan with automatic
transmission, is expected to achieve zero to 100 kph acceleration in just 6.9
seconds, a substantial improvement against 8.8 seconds for the equivalent petrol
model. Even more impressive is 80 to 120 kph acceleration on 'kick-down' in only
5.5 seconds.
"Hybrids are certainly interesting for Saab in the future and this project
allows us to evaluate and explore the potential of hybrid technology in
combination with BioPower," says Jan Åke Jonsson, Saab Automobile's Managing
Director.
"Although the exact hybrid application shown in this concept does not
currently figure in our production plans, the project has been extremely
valuable in helping us further our expertise. It shows how we could develop the
sporty performance associated with Saab while using only renewable resources and
saving energy overall."
The Saab BioPower Hybrid Concept is the first project to be announced under a
joint investment program between General Motors R&D (Research and
Development) and the Swedish government. This has established a research and
development office in Trollhättan, Sweden, focusing on vehicle safety, engine
emissions and advanced manufacturing in collaboration with Swedish universities,
research laboratories and suppliers.
Saab is a 100 percent subsidiary of General Motors which is committed to
reducing vehicle emission and improving fuel economy through the implementation
of a three-tiered, advanced propulsion technology strategy. The ultimate goal is
the introduction of hydrogen fuel cell powered vehicles that emit only water and
remove the vehicle from the environmental debate.
In the near to mid-term, hybrid propulsion will bridge the gap between
today’s technology and tomorrow’s hydrogen fuel cell powered vehicles. GM is
also focused on introducing alternative fuels and new technologies to improve
the efficiency of internal combustion engines and transmissions, further
reducing vehicle emissions and increasing fuel economy.
BioPower propulsion
The Saab 9-5 2.0t BioPower is already an outstanding sales success in Sweden,
where it is currently the best selling flex-fuel vehicle on the market and able
to exploit a fast-developing network of filling station selling E85 (85%
bioethanol/15% petrol) fuel.
The Saab BioPower Hybrid Concept now goes a step further by using an engine
fuelled by pure E100 bioethanol. This is a BioPower evolution of the current
all-aluminium, 16-valve 2.0-liter turbo engine in the Saab 9-3 range. It now
develops 191 kW/260 bhp and an impressive 375 Nm maximum torque, 24 per cent and
25 per cent more respectively than on petrol. The engine incorporates an
integrated starter generator (ISG) and also charges a 300-volt battery bank,
mounted under the floor of the trunk.
It retains a flex-fuel capability and features a Spark Ignited Direct
Injection (SIDI) system for optimum combustion with E100; ensuring the same cold
starting performance as a normal gasoline engine. Variable inlet and exhaust cam
phasing is used for optimum breathing and more durable valves and valve seats
are fitted, together with bioethanol-compatible materials for the fuel system.
The compact 42-Volt ISG, built into the flywheel between the engine and
transmission, is the power behind the Saab BioPower Hybrid Concept's
fuel-saving, stop/start
functionality. It serves a multi-functional role as a starter motor,
alternator and 15 kW engine power booster, while also helping to iron out
residual crankshaft vibrations.
For the Saab BioPower Hybrid Concept application, a series of further steps
are taken to optimise the engine's fuel saving capacity. Auxiliary functions,
such as the water pump, air conditioning and power steering systems, are now
removed from the engine's belt drive and electrically powered instead, through
the hybrid system.
The five-speed automatic transmission, with Saab Sentronic sequential
selection, includes an all-wheel-drive capability by the simultaneous addition
of electrically powered drive to the rear wheels.
Hybrid booster
A parallel hybrid system has been adopted, where the control strategy is
based on efficient 'energy management' - recovering, storing and feeding back
energy that is otherwise lost in a vehicle powered only by an internal
combustion engine. The engineering team have utilised General Motors' hybrid
experience in the development of stop/start engine functionality, electric
rear-wheel drive systems and regenerative braking. Apart from converters to
manage AC/DC and 12,42 and 300-volt interfaces, the system consists of just
three core components: two electric motors and a battery bank.
Electric energy storage is provided by a 42-cell, 300-volt lithium-ion
battery bank, designed to be entirely maintenance-free throughout the lifetime
of the vehicle. Its performance is carefully monitored and governed by an
electronic control unit, through which electric current from the engine is fed.
This power pack is accommodated under the floor of the trunk, without taking
up any stowage space, as demonstrated in the Stockholm show car. There is also
the possibility of providing a 'plug out' facility, through an integrated
220-volt DC/AC converter, as a power source for outdoor appliances.
The battery supplies a compact 38 kW electric motor located between the rear
wheels which powers a transmission differential and drive shafts. At low speeds,
this Rear Drive
Unit (RDU) is able to briefly generate 666 Nm of additional torque.
In reverse operation, the motor acts as a generator to provide 'regenerative
braking'. It automatically recovers kinetic energy otherwise lost during braking
and converts this into additional battery charging. It also performs the same
function whenever the driver lifts off the throttle, harnessing the energy in
the rotating drive shafts. This is achieved without any perceptible change in
the rate of deceleration.
The second electric motor is the integrated starter generator (ISG) located
within the flywheel between the engine and main transmission. On demand, it
contributes 15 kW of additional power and 120 Nm of extra torque to the output
of the engine through the front wheels.
Driving Benefits
The sophisticated electronic control of the hybrid componentry is matched to
the operating parameters of the BioPower engine to provide seamless power
assistance and power saving functionality.
Under transient driving conditions, both electric motors are activated to
augment the power of the engine, increasing standing start acceleration and
in-gear performance for safe overtaking. This briefly raises total power by as
much as 28 per cent - without raising fuel consumption.
At take off, the Saab BioPower Hybrid Concept also exploits the instant
torque generation of its electric motors, smoothly adding strong, accelerative
power during the engine's pick-up, from tick-over to about 1,500 rpm. It is
during this phase that the available pulling power, or torque, is more than
tripled.
An estimated fuel of saving of 5-7% is provided by the automatic engine
stop/start function. Whenever the vehicle is stationary, the engine is
immediately shut-off to save fuel. As soon as the brake is released, it is
automatically started again by the powerful ISG. The operation is carried out
seamlessly and requires no input from the driver.
In congested driving conditions, fuel saving is taken a step further by the
Saab BioPower Hybrid Concept's 'Zero Mode' operation - giving zero fuel
consumption, and, of course, zero emissions - which can be selected by the
driver via a button in the central console. At speeds below 50 kph, 'Zero Mode'
will shut off the engine and again switch the car over to electric power only
through the RDU. In this mode, the battery bank provides a range of between 10
and 20 kilometres. The engine is smoothly re-engaged whenever the battery status
approaches a low charge level or the electronic throttle opening requires
acceleration beyond the 50 kph operating limit.
To optimise the availability of 'Zero Mode', a plug-in-feature is available
which allows the battery bank to be connected to a mains electricity supply for
additional charging in the garage. This would, for example, allow a driver
commuting in heavy traffic to immediately resume in 'Zero Mode' the next morning
after arriving home the previous evening having used up all its range. A neat
socket is located behind the Saab badge on the 9-3 BioPower Hybrid Concept's
trunk lid.
Whenever the engine is shut down all auxiliary functions, such as the power
steering, air conditioning and lighting, remain unaffected because they now
permanently electrically-powered through the battery. The removal of unnecessary
loadings on the engine further contributes to fuel economy and in mixed driving
the estimated range of Saab 9-3 BioPower Hybrid Concept test vehicles, with a
standard 62 litre tank, is a competitive 800 kms. Estimated fuel consumption.
7.8L/100 km, mixed driving.
Finally, in low grip road conditions, traction can be optimized by the
addition of rear-wheel-drive for improved handling and safety. For example, when
the electronic traction control system (TCS) is activated at the front wheels,
the car can be balanced by the application of rear drive.
Driver instrumentation for the Saab BioPower Hybrid Concept is as discreet as
the installation of its hybrid engineering. In the main instrument cluster,
icons are illuminated to indicate when the car is running on engine and/or
electric power. An additional gauge is also fitted to show the power status of
the battery bank. Under electric power, the needle will steadily fall and then
rise again when the engine provides charging. The turbo boost gauge is
calibrated by tree icons, a playful reminder of the car's renewable energy
source.
In overall operation, the Saab BioPower Hybrid Concept is designed to deliver
enhanced performance and valuable energy savings. The concept can enrich driving
appeal while also moving further towards the goal of sustainable mobility.
Further Information:
GM has a diverse hybrid program, with three separate systems designed to
provide an opportunity for more consumers to own a hybrid vehicle and benefit
from increased fuel savings. Next year, GM will introduce in the USA the world’s
first two-mode hybrid system in the Chevrolet Tahoe and GMC Yukon full-size
SUVs. This will be mated with Active Fuel ManagementTM to deliver a fuel economy
improvement of at least 25 per cent. The Saturn Vue Green Line SUV, with a new,
more affordable hybrid system giving estimated fuel savings of up to 20 per
cent, goes on sale in the US this summer. Hybrid vehicles currently on the US
market include the Chevrolet Silverado and GMC Sierra pickup trucks with fuel
saving stop/start technology.
Bioethanol fuel is produced commercially from agricultural crops such as
sugarcane, corn and other forms of biomass. When considering CO2 emission
savings, the whole chain - feedstock, fuel supply and vehicle combustion - must
be considered Dependent on its source and its production process, the use of
bioethanol can reduce CO2 emissions up 90 per cent against fossil gasoline. This
is because emissions from its combustion are balanced by an amount of CO2 that
is removed from the atmosphere when energy crops are grown. In this way, the CO2
present in the atmosphere remains in a natural cycle, whereas CO2 emissions from
the use of a fossil fuel - such as gasoline or diesel - add new CO2 to the
atmosphere which has been locked up in oil deposits underground.
Image available online at: media.saab.com and autonews.net.au
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