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Advanced combustion strategies for direct injection gasoline engines require high performance fuel injectors. They must perform precise fuel metering, enhanced linear flow range and multi-pulse injection cycles in order to meet tight emission limits and low fuel consumption. Cold start is the most critical phase concerning emission levels. The performance of outwardly opening piezo-electric actuated fuel injectors is compared with conventional inwardly opening solenoid injectors. The investigation focuses on dosing performance, temperature influence and the impact of production tolerances. Besides full valve needle lift, both types of injectors are also analyzed in ballistic operating mode for minimum injection quantities. Compared to piezo injectors solenoid injectors show a much larger tolerance band at low fuel quantities. A new sensorless closed-loop control system results in substantial improvement of the dosing performance of solenoid injectors.

Hybrid vehicles are becoming more and more attractive due to their reduced emissions and their higher fuel efficiency. Storage of electrical energy is the most critical aspect of hybrid automobiles. Therefore, an exact knowledge of the behavior of the battery and further electrical storage elements is mandatory. Their nonlinear characteristics over wide ranges of current magnitude, transient period, temperature and state of charge must be evaluated. Battery aging is another matter of increasing importance. For this reason, an automated battery test bench has been developed which is capable of reproducing high dynamic loads in both charging and discharging direction. Pulse rise times are in the range of a few microseconds at maximum currents up to 1500 A. The quasi-static charge and discharge power can reach 20 kW. Optimized characterization programs enable a rapid extraction of battery behavior parameters as well as capacitor characteristics.

The sensorless control of electromagnetic actuators for variable valve train derives the information about the valve movement directly from the current and voltage of the operating coils, no further sensor used at the actuator. The movement of armature and valve is heavily influenced by the cylinder pressure, especially during opening of the exhaust valve. Between two consecutive opening events, this pressure can vary by up to 3 bars. An early detection of pressure variation is essential in order to adjust the proper catching energy of the active coil. At the beginning of the armature movement, a degradation of the magnetic flux through the coils occurs which is caused by eddy-currents and magnetic remanence and results into an induced voltage. The information about the required energy adjustment of the catching coil can be calculated from this voltage. The algorithm allows a safe and soft landing at pressure variations of up to 3 bars.

Precise fuel metering and high linear flow ranges (LFR) are the key issues for advanced injection systems for diesel and gasoline engines. They ensure lower emission, lower noise and higher fuel efficiency. Fast-switching solenoid injectors show high valve needle impact velocities and thus bouncing at injector closing. This causes multiple parasitic injections which reduce injection precision and deteriorates emission and efficiency. Mechanical and hydraulic anti-bounce concepts reduce the injection dynamic range while electronic open-loop controlled concepts are instable. For this reason a new sensorless electronic closed-loop anti-bounce solution able to reduce bouncing effectively and providing robust soft landing under all operating conditions was developed.

New cylinder impulse charge systems permit higher torque at low speed and promise substantial downsizing potential ongoing with reduced fuel consumption and lower emissions. Their immediate response avoids the disturbing delay of turbochargers. Using a fast switching valve in the air intake manifold, they generate a dynamic pressure increase, which provides higher cylinder air mass filling. The short transient times needed for the valve opening and closing process together with the required low air leakage rate call for an effective drive. Electromagnetic spring-mass actuators are well suited for this task. They generate high control forces over long distances and can be designed for transient times below 2 ms. However, they suffer from high impact energies at the stop positions und cannot be used without movement control for the armature. Tight commercial conditions restrict the application of sensors and complex hard- and software.

At present, diesel injection systems in automobiles with piezo element drives are replacing solenoid types due to their faster electro-mechanical properties. Their better fuel dosing characteristics offer lower fuel consumption, reduced noise and lower emissions. The limited elongation of the applied piezo elements within some tenth of micrometers makes these systems sensitive against mechanical tolerances, thermal effects and wear-out. Using the piezo element both as an actuator and as a sensor for the elongation and force allows an insight into the injector. The performance of this actuator-sensor behavior is shown together with a self-compensating loop for idle lift drift and a minimum fuel dosing control.

The reliable access to electrically stored energy is becoming a critical parameter for the proper operation of modern vehicles. The total energy demand of electrical consumers in passenger cars is rising almost exponentially together with an increasing ratio of the peak to average current level. Such conditions can stimulate severe interactions between the various systems on the one hand, while on the other hand the battery charging state varies over a wide range. Recent field problems of high end cars from various vehicle manufacturers demonstrate the importance for an improved interaction analysis of the complete electrical system during the design phase and before the introduction of new functions. An efficient battery management is essential for modern vehicles to ensure a minimum state of charge and a proper lifetime of the battery. The electrical energy storage in hybrid vehicles which use the battery to buffer the combustion engine is even more important.