Search Results

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.

A test center for aging analysis and characterization of Lithium-Ion batteries for automotive applications is optimized by means of a dedicated cell tester. The new power tester offers high current magnitude with fast rise time in order to generate arbitrary charge and discharge waveforms, which are identical to real power net signals in vehicles. Upcoming hybrid and electrical cars show fast current transients due to the implemented power electronics like inverter or DC/DC converter. The various test procedures consider single and coupled effects from current profile, state of charge and temperature. They are simultaneously applied on several cells in order to derive statistical significance. Comprehensive safely functions on both the hardware and the software level ensure proper operation of the complex system.

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.

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.