Mike-- You have been this threads best poster on 42volt SLI developments. here is a great piece of news from Siemens website, that they have developed and are going into production with a 42v Integrated Starter Alernator and Damper. All my battery chums (or at least the cogent ones) feel that NiMh is the only chemistry that can be the battery here: small volume, good amperage, best cycle life etc.
heres the article:
Automotive Systems
Frankfurt am Main, September 1999
Viewpoint IAA '99
New Generator for High Power
42-Volt Starter-Alternator
High Efficiency in all Speed Ranges
A new power plant that generates real power for cars. Low engine speed, cold starting? No problem for this technology. We are
talking about the starter-generator currently under development at Siemens Automotive, and which will be supplied to the
automotive industry by spring of 2002 as standard equipment. This will also mark the decisive transition from 14 to 42 volts in
vehicle electric systems. A development that has generated enormous interest in the automotive industry.
An increasing number of energy consumers and the implementation of new technology - from electrical power assisted steering to
electromechanical valve train - require generator outputs from 4 to 8 kilowatts across the entire engine speed range - a lot more than the power
provided by conventional generators. A solution emerging for the next millennium is a completely novel system with an integrated induction
machine to generate and distribute energy under the hood.
The starter-generator from Automotive Systems Development in Regensburg ready to go into volume production reaches a peak generator
output of 8 kW with an efficiency of more than 80% across the entire speed range. For comparison: A conventional generator outputs 1.5 kW
with a maximum efficiency of 70%, which drops down to a meager 30% at high speeds.
With this starter-generator, the engineers at Siemens intend to replace the starter, the generator and the flywheel. It should also be noted that this
technology is linked to a number of beneficial applications, such as, for example, an automatic start-stop system or pulse start. This results in
synergy effects - the use of electric energy can be optimized and fuel consumption and emissions are reduced. The power to be transferred,
technical feasibility of consumer components and permissible touch voltage results in a 42 volt board net.
Due to extremely compact dimensions, the starter-generator can be placed directly on the crankshaft between the engine and the transmission.
High electric power output even at low speeds means that short-term shutoffs of luxury features, such as the air conditioner, seat heater or
rear-window heater, are unnecessary. An added bonus is the transmission of force is contactless; therefore the starter-generator is wear- and
maintenance-free.
As an important auxiliary function, the Siemens starter-generator is equipped with a convenient automatic start-stop system which is not subject
to any wear because of its brushless design and therefore remains functional unlimited. This system switches off the combustion engine at zero
load - at traffic lights, for example - and automatically restarts it in less than one hundred milliseconds the next time the gas pedal is pressed.
That's not all, however: The pulse-start technology accelerates the combustion engine to the required cranking speed (for example the idle
speed) and only then initiates the combustion process, another feature that helps reduce both fuel consumption and emissions.
The starter-generator is just as versatile when it comes to other disciplines. In the boost mode, the starter briefly serves as a second engine to
drive the vehicle off or accelerate it in the low-speed range. Depending on the configuration of the starter-generator and battery, this provides a
short-term power boost of an amazing 15 kW. In the so-called retarder mode, the starter-generator shows off yet another strength by its ability to
convert kinetic energy to storable electric energy.
Driveability is improved significantly by the torsional-vibration damping provided by the starter-generator. Without active damping, load reversals
or abrupt acceleration, for example, may result in low-frequency vibration excitation in the drive train which, in turn, may cause jerks.
In parallel to the starter-generator, Siemens Automotive is developing a production-ready 42-volt vehicle electric system because only this
electrical platform will be able to supply the energy required for new and power-hungry functions in the car of the future. For example, the
electromechanical valve train EVT and the electrically controlled air-condition will have power requirements of about 3 kW each. An important
argument that speaks for this electric system - and against retaining the 14-volt system - is the smaller wiring harness cross-section with all the
advantages of simplified, less costly and lighter weight installation.
Siemens Automotive plans to introduce the new electric system generation step-by-step within the next five years - depending on decisions to
be made by the automotive industry. Vehicles with two electric systems are conceivable during a transitional phase; which might promote the
use of new features for increased safety and comfort in the vehicle.
Press photo available.
Please visit the Internet at www.siemens.de/at
Ansprechpartner:
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Siemens AG
Corporate Communications
Press Office
D-80312 Munich
Reference number: AT 199909.016 e
Press Office Automotive Systems
Ralph Heinrich
D-93026 Regensburg
Tel.: +49-941 790-5594; Fax: 790-5103
E-mail: ralph.heinrich@at.siemens.de |
