Electronic Systems

High performance multi-valve gasoline engines will maintain their dominance as the preferred prime mover for passenger cars worldwide. During the last few years, the global marketplace has witnessed a number of improvements in these engines in such areas as fuel economy, torque characteristics (due to increased low end torque), exhaust emissions, dynamic behavior and NVH behavior.

FEV's patented Electromechanical Variable Valve Timing System (EMVT) allows fully variable operation of the intake and exhaust valves with minimal changes to the cylinder heads of gasoline engines. The system also allows a completely unthrottled load control of gasoline engines. In addition, there are specific parameters that significantly influence the gas exchange and combustion process to optimize engine behavior.

Due to the unthrottled load control and the minimized gas exchange pumping losses, as well as an optimized residual gas fraction, the EMVT system is capable of demonstrating the following benefits:

• Approximately a 15% increase in fuel economy
• Reduced NOx exhaust gas emissions, due to the control of residual gas fraction
• Substantially reduced exhaust gas Hydrocarbon (HC) emissions during cold start and warm-up operation
• Increased low end torque
• Improved engine transient behavior
• High potential for idle speed reduction, due to minimal residual gas fraction

Actuator Concept

FEV developed an electromechanical valve actuator to accomplish independent variable valve timing, which operates as a free oscillation system with electromagnets holding the valve in both final positions. The switching time of the electromechanical actuator is approximately 3 ms to open or close the valve. The valve opening and closing time can be adjusted freely by the oscillation time. Due to the adapted valve control system, a valve deactivation and a cycle-resolved cylinder deactivation is possible. This results in further improvements in fuel economy.

The switching time and the seating velocity do not depend on engine speed and engine load. The energy requirement for the alternator in a 16-valve application ranges from 0.08 up to 0.11 bar Friction Mean Effective Pressure (FMEP) (generator efficiency: 80%) over the engine speed under the part load operational range. The energy requirement depends on engine design parameters, such as valve size and generator efficiency. Therefore, these requirements would be in the range of roller valvetrains.

The current system is capable of operating at engine speeds up to 6,500 rpm. Four-valve applications are accomplished with packaging that meets the requirements of modern production engines. In addition, hydraulic lash adjuster operation is also possible.

Fuel Consumption, Exhaust Gas Emissions and Engine Performance

It is possible to control the amount of cylinder charge and residual gas fraction of Spark Ignition (SI) engines through variable valve timing. By controlling the cylinder charge with the load control strategy, early intake valve closing and the gas exchange pumping losses are minimized with a corresponding improvement in fuel economy.
The combustion process can be optimized by changing the composition of the cylinder charge by varying the intake valve opening and exhaust valve closing timing as a function of load and speed. An adapted residual gas fraction improves fuel economy and reduces exhaust gas emissions, especially NOX emissions. Additional advantages of FEV's EMVT system can be used to improve other engine performance parameters such as combustion stability during cold start and warm-up by late intake valve opening or a special operation strategy for the exhaust valve opening for rapid catalyst heating.

Under full load conditions, the maximum volumetric efficiency is increased by optimized timing for intake valve closing. Additionally, the efficiency is increased by minimizing the residual gas fraction by optimizing the timing of intake valve opening and exhaust valve closing. The reduced residual gas fraction also avoids engine knocking. The improvement in the electromechanically-controlled engine's Brake Mean Effective Pressure (BMEP) is about 30% at low engine speeds.

FEV's investigations of various multi-cylinder 4-valve engines have successfully demonstrated improvements in fuel economy and exhaust gas emissions at part load, as well as increased volumetric efficiency at full load.

FEV's EMVT Project Center ensures that our clients receive a high level of support. FEV welcomes the opportunity to transfer its expertise and experience with advanced EMVT technology, design, and combustion system development to the automotive industry.

Fuel Cell System Development

Electric vehicles, which generate electric power from on board hydrogen powered fuel cells, provide a potential solution for sustainable, individual mobility for the future. Technical feasibility of fuel cell vehicles have been shown with various demonstrator vehicles, like the Hy-Power® developed by the Paul-Scherrer-Institute in cooperation with FEV and VW, as well as small fleets from different manufacturers worldwide. Several OEMs are in the process of developing commercially available fuel cell vehicles, which intend to be on the market by between 2010 and 2015.

During the next several years, the main focus of development will be on cost-reduction and increasing efficiency, durability and storage capacity. In parallel, optimizing the control strategy, design for manufacturing and automotive-related testing of the components will also be addressed.

The trend towards increased electric power consumption in vehicles requires new approaches for power generation. Fuel cells can be used as an Auxiliary Power Unit (APU) for power generation with high efficiency, independent of the internal combustion engine. Also, hybrid technology establishes new areas for fuel cell APUs to extend the vehicle's range for electric driving and boost systems for acceleration or high-speed driving. Therefore, fuel cell systems need on-board hydrogen generation from conventional fuels.

FEV provides the following services for developing fuel cell systems:

• System simulation
• Development of air supply units
• Catalytic fuel reformer and gas cleaning units
• Optimization of system controllers
• Performance and durability tests of fuel cell stacks and systems

FEV operates independently from fuel cell manufacturers and will find the best possible solutions for each application. By utilizing our capabilities in fuel cell system development, packaging and design, vehicle integration and electronics, FEV is well suited to build up complete fuel cell demonstrator vehicles.