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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.

Replacing the traditional camshaft of spark ignition engines by a variable valve actuation (EVA) system promises noticeable fuel savings and substantial improvement of the motor torque [1]. Up to now, all known electromagnetic EVA systems apply one bulky central electronic control unit (ECU) together with complex wiring harness. A mechatronic approach for such system, where each actuator is joint together with its own control electronics, offers substantial performance and cost benefits. Extraordinary environmental conditions arise for such mechatronic system which is directly mounted on the cylinder head of the engine. Ambient temperatures up to 125°C together with vibrations, which are generated by the impact of the armature of the electromagnetic actuator, ask for a new assembly technique of the electronic. This paper describes the systematic approach for the design of such complex mechatronic system.

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.

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.

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.

A promising approach for the variable valve actuation in spark ignition engines is based on electromagnetic actuators for the valve drive. The movement of the armature results from two opposite electromagnetic drives, supported by two springs. Without proper control of the current through the coils during flight time, the armature will hit the opposite position at high velocity, thus producing acoustical noise and reducing the lifetime of the actuator. This paper presents a new concept to achieve a soft landing with velocities in the range of 0.1 m/s. The applied control circuit requires no additional sensor for the valve position or speed and is only based on the observation of the electrical coil signals. Together with the optimized control strategy, the system complexity is minimized, which results into substantial cost savings.