This paper describes the development of different active measures to reduce torsional vibrations in power trains. The measures are based on concepts developed for active mounts to reduce the transmission of structure-borne sound. To show the potential of these active measures and investigate their mode of operation to influence torsional vibrations, numerical simulations of powertrains with different active measures were done. First experimental results from tests on an experimental (reduced size) power train were used to align the numerical models.
The work was done within the project 'LOEWE-Zentrum AdRIA: Adaptronik - Research, Innovation, Application' funded by the German federal state of Hessen, and the Project AKTos: 'Active control of torsional vibrations by coupling elements' placed in the research Framework program 'Navigation and Maritime Technology for the 21st Century' funded by the German Federal Ministry of Economics and Technology.
This paper describes the development of a safety-clutch by using magnetorheological fluids (MRF) to switch the
transmission torque between a motor and a generator in a bus-like vehicle. The clutch is based on a new design
combining an axial MRF-actuator and a ball coupling mechanism. This so called "MRF-ball-clutch" avoids the
disadvantages of traditional bell- or disc-MRF-clutch designs where the torque is transmitted by the MRF which leads to
a self-heating due to the shearing forces in the fluid and a more or less significant drag torque caused by limitations of
the relation between minimal and maximal transmittable torque. The safety clutch based on the new MRF-clutch design
requires a minimum of power consumption and allows switching high torsional moments in a very compact, lightweight
and robust design.
The work was done within the Fraunhofer System Research for Electromobility FSEM, founded by the German Federal
Ministry of Research and Technology.
The goal of the project is to develop active mounts that isolate the main power engine using piezoceramic actuators
operating in the load transmission of the common engine mounts. These mounts are to use high-frequency conducted
adaptive countermeasures to reduce the unwanted vibrations caused by the motor. Integrating the active piezoceramic
based Interfaces directly in the load transmission of the mount, which is a safety critical component, the system
reliability of these mounts will face special challenges.
Designing these active mounts several measures on the target ship have been done. Based on these measurements
simulations of the dynamic behavior of the ship, the passive mounts and the aggregate have been done to design the
active mounts and to simulate its properties to optimise and to design e.g., the adaptive control in a early state of the
project. For the experimental research a test rig with a reduced ship structure and the main engine was build up at the
LBF to investigate the performance and the system reliability of the active mounts.
The project started in 2004, has an intended duration of three years and will end with the presentation of a ship with the
abovementioned active mount.
The Fraunhofer Gesellschaft is the largest organization for applied research in Europe, having a staff of some 12,700, predominantly qualified scientists and engineers, with an annual research budget of over one billion euros. One of its current internal Market-oriented strategic preliminary research (MaVo) projects is FASPAS (Function Consolidated Adaptive Structures Combining Piezo and Software Technologies for Autonomous Systems) which aims to promote adaptive structure technology for commercial exploitation within the current main research fields of the participating FhIs, namely automotive and machine tools engineering. Under the project management of the Fraunhofer-Institute Structural Durability and System Reliability LBF the six Fraunhofer Institutes LBF, IWU, IKTS, ISC, AiS and IIS bring together their competences ranging from material sciences to system reliability, in order to clarify unanswered questions. The predominant goal is to develop and validate methods and tools to establish a closed, modular development chain for the design and realization of such active structures which shall be useful in its width and depth, i.e. for specific R&D achievements such as the actuator development (depth) as well as the complete system design and realization (width). FASPAS focuses on the development of systems and on the following scientific topics: 1) on design and manufacturing technology for piezo components as integrable actuator/sensor semi-finished modules, 2) on development and transducer module integration of miniaturized electronics for charge generating sensor systems, 3) on the development of methods to analyze system reliability of active structures, 4) on the development of autonomous software structures for flexible, low cost electronics hardware for bulk production and 5) on the construction and validation of the complete, cost-effective development chain of function consolidated structures through application oriented demonstration structures. The research work will be oriented towards active vibration control for existing components on the basis of highly integrated, both, more or less established and highly innovative piezoelectric actuator and sensor systems in compact, cost-effective and robust design combined with advanced controllers. Within the presentation the project work will be shown using the example of one demonstration structure which is a robust interface, here for being integrated within an automotive spring strut system. The interface is designed as a modular, scalable subsystem. Being such, it can be used for similar scenarios in different technology areas e.g. for active mounting of vibration-inducing aggregates. The interface design allows for controlling uniaxial vibrations (z-direction) as well as tilting (normal to the uniaxial effect) and wobbling (rotating around the z-axis).