Top 10 Technologies 2000
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Readers have selected the most interesting technology stories appearing in Automotive Engineering International during the past year. The rankings are based on the reader responses from feature articles and shorter technology items. Some of the stories appear here in shortened form.
Starter/alternator for 42 V
 A host of "energy hogs" - radio, rear window defroster, and up to 50 control motors for automatic windows and other convenience features - rely on the current 12-V automobile power network. When they all demand power, especially in adverse winter conditions and with insufficient battery charge, the capabilities of current electrical systems are exceeded.
Sachs believes it has solved this problem with its DynaStart system, which makes available enough power for the 42-V power networks of the future. The compact, electronically controlled unit unifies the starter and alternator, making possible automatic start/stop functions, braking-energy recuperation, and improved acceleration (with additional torque on the crankshaft). In addition, it improves vibration damping because it is integrated into the powertrain and it can allow the electrification of auxiliaries previously driven by V-belts (such as pumps and AC compressors), which is possible with a 42-V power network. It can make better use of the available engine power and thus contribute to reducing consumption and emissions by up to 20%, according to Sachs.
By saving weight compared to the separate starter and alternator combination, the DynaStart helps automakers achieve their goal of saving fuel with lightweight construction. The space-saving installation in the powertrain between the crankshaft and gearbox allows its overall length to be reduced.
The construction principle behind the system is a constantly excited electric synchronous machine. It consists of a rotor with permanent magnets arranged around its outside and a stator with a sheet packet, windings, and connecting terminals. According to Sachs, the advantages derived from the system's compact configuration, simple rotor design, and large air gap include high wear resistance and ease of integration.
The technology behind DynaStart was originally developed over the course of ten years for electric traction drives. The system's functionality has already been proven in extensive rig testing in collaboration with development partners. The first development project in a compact-class vehicle is currently undergoing testing.
Fuel-cell concepts and technology
Auto manufacturers around the globe are placing their bets on fuel cells as major long-term energy-conversion solutions because they offer good fuel economy and substantially lower emissions, particularly of CO2. Like batteries, fuel cells rely on chemical reactions at electrodes to convert energy from chemical to electrical form. Specifically, fuel cells electrochemically combine oxygen from the air with hydrogen from a hydrocarbon fuel to produce electricity. Unlike batteries, fuel cells store the reactants outside of the electrodes. They are fed to the cell as "fuel" for the reaction.
A fuel-cell system can use the hydrogen from any hydrocarbon fuel, though a fuel reformer may be required in some cases. Since the fuel cell relies on chemistry and not combustion, emissions from this type of a system are much lower than those from even the cleanest fuel-combustion processes. There are a number of different types of fuel cells, but two - proton exchange membrane (PEM) and solid oxide types - have been singled out for automotive use. With the exception of pioneering work done by Delphi Automotive Systems, Global Thermoelectric Inc., and BMW AG, most automotive fuel cells being developed are of the PEM variety.
A single PEM fuel cell consists of a membrane electrode assembly and two flow field plates. Each membrane electrode assembly consists of two electrodes (anode and cathode) with a thin layer of platinum catalyst bonded to either side of a PEM. Hydrogen gas and air are supplied to the electrodes on either side of the PEM through channels formed in their flow field plates. Hydrogen flows through the channels to the anode, where the platinum catalyst promotes its separation into protons and electrons. On the opposite side of the PEM, air flows through the channels to the cathode, where oxygen in the air attracts the hydrogen protons through the PEM. The electrons are captured as useful electricity through an external circuit and combine with the protons and oxygen to produce water vapor on the cathode side. Individual fuel cells producing about 1 V are combined into a fuel-cell stack to provide the amount of electrical power required. Fuel cells have an energy conversion efficiency approaching 45%.
OEM and supplier fuel-cell technical developments highlighted in the article included:
Ballard Power Systems' next-generation Mark 900 fuel-cell stack uses lower-cost materials and is designed for larger-volume automotive manufacturing. It is significantly more powerful and compact than any PEM fuel cell publicly shown, according to the company.
General Motors engineers successfully operated GM-designed and -built fuel-cell stacks at temperatures as low as -20°C (-4°F). Subzero startup tests were repeated on the same GM stack as many as 25 times with no reduction in performance.
Delphi Automotive Systems and BMW AG are working on a solid-oxide fuel cell as an auxiliary power unit (APU) for gasoline engines. Delphi will develop the fuel-cell system, and BMW will integrate the unit into a vehicle.
The U.S. DOE demonstrated the technical feasibility of an ultra-compact fuel reformer that uses readily available fuel such as gasoline for its hydrogen component to power fuel cells. In laboratory tests, engineers have shown that one of the most critical components of the fuel reformer can be made at least 1/10 the size of current units without sacrificing efficiency.
Energy Conversion Devices, Inc. has developed special alloys engineered to store and release hydrogen with solid-state hydrogen storage of 7 wt% at a 300°C (572°F) desorption temperature.
Energy Partners, L.C. received a U.S. DOE contract to supply Epyx Corp. with a high-performance PEM fuel-cell subsystem. Along with an advanced fuel reformer, the multi-fuel-cell system is capable of generating 10 kW (13 hp) of electrical power from a variety of fuels.
Epyx Corp. successfully demonstrated high-efficiency and low-emissions operation of a fuel-cell power system using Syntroleum synthetic fuel and a Plug Power fuel-cell stack. The synthetic fuels contain no fuel-cell catalyst poisons such as sulfur, metals, or aromatics.
Pudenz has developed fuses specifically for fuel-cell vehicles to protect heating/air-conditioning systems, dc/dc converters, and systems that are fed directly by the driveshaft of the fuel-cell vehicle.
Proton Energy Systems has developed systems that can generate high-pressure hydrogen to significantly accelerate the creation of a hydrogen infrastructure for fuel-cell vehicles. The technology will enable onsite production of high-pressure, high-purity hydrogen suitable for fuel-cell vehicle refueling.
Ecostar Electric Drive Systems is developing controls that integrate electronic fuel-cell functions for improved performance and quality while significantly reducing package size and cost. Development for nonautomotive uses will increase manufacturing volumes, thus lowering costs for all fuel cells.
Hydrogen Burner Technology's Underoxidized Burner makes use of a noncatalytic process to generate hydrogen from common fossil fuels that is convenient, inexpensive, flexible, and virtually emissions-free. A small portion of the burned fuel allows for an exothermic condition that liberates hydrogen.
Mobil Corp. and Ford Motor Co. have made significant progress in developing an onboard gasoline fuel processor that is smaller, lighter, and less expensive than current reformer technology while maximizing the use of the existing fuel infrastructure.
In addition to these developments, fuel-cell vehicles highlighted in the article included the GM Precept, Ford TH!NK FC5 and P2000 HFC, DaimlerChrysler NECAR 4, BMW 7 Series, Honda FCX, Daihatsu Move EV-FC, and Nissan FCEV.
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