Modularisation of the wire harness to reduce complexity
DST Dräxlmaier Systemtechnik GmbH
Mr. Wortberg is Systems and Projects Engineer, Innovation Management
Wire harness concepts
Development of a modularisation concept
To be able to manufacture wire harnesses automatically, today’s on-board electrical system and wire harness architectures need to be significantly modified.
Sub-project 3 aims to provide solution approaches for tomorrow’s on-board electrical system architectures. During the first phase of the sub-project, a proposal for reducing the variety of parts in the wire harness was developed. Phase 2 addresses the topic of the “standardised system connector” that is needed to make modularisation possible: if the wire harness is divided into smaller, automatable modules, these require clearly defined and standardised plug connectors at their ends, so-called system connectors.
Starting point and motivation
Producing a main wire harness automatically in its current form would not be economical at all. The main reasons for this are as follows:
- The cables are too long
- There is too great a variety of components
- Too much interlinking/interweaving in large wire harnesses
- Special lines and non-automatable parts (e.g. bushings)
The excessively long cables could be prevented by adjustments to the production machines. On the other hand, the high variety of parts, the extensive interlinking and special lines are obstacles to automation that needs to be reduced or eliminated.
The fact that the number of different components is continuously increasing ensures increasing component variety. One reason for this is the significant increase in functions that need to be provided in a vehicle (excessive display of customer functions. Where there used to be only: accelerating, braking, steering, headlights, today we also have: air conditioning, airbag, central locking, entertainment, Android/Apple integration).
Any additional or new function (e.g. the airbag) triggers a chain reaction of further process steps. A coordinating control unit, several sensors (accelerometers) and various actuators (ignition pills) are required to control and network the component. All components require fail-safe connections to each other and guarantee a constant power supply. The
“connect as it comes”
approach is always at odds with cost reduction and optimisation of customer wishes
(Keywords: electromagnetic compatibility and available installation space).
Another factor is special components, some of which make automation impossible and therefore, to a large extent, have to be manufactured manually. The results vary between an extremely branched, meshed or interwoven wire harness.
Approaches need to be found and concepts developed that lead to a reduction in the number of variants (focus of phase 1), enable/promote automated production (focus of phase 2) and thus provide an innovative solution for the on-board electrical systems of tomorrow.
Current working focuses
A current focus of work is the targeted modularisation of the on-board electrical system. The challenges of modularisation lie in describing the system boundaries in a meaningful way and defining suitable interfaces between modules and the rest of the system.
Due to the modularisation of the on-board electrical system and the resulting energy and data interfaces that need standardising, corresponding plug systems or solutions need to be generated and validated.
In the future, partitioning concepts that will allow a practical modularisation of the entire on-board electrical system will be developed. This division into modules reduces the complexity of the individual, much smaller wire harness modules. However, the possibility of being able to map today’s variance should not be diminished. The complexity is shifted from the single-piece wire harness into a) smaller modules and b) their combinatorics with each other. The solution approaches that have been developed for modular division need to be evaluated on the basis of their feasibility with all parties involved and then combined into a uniform concept.
The next step is to compare the underlying interconnection paradigm of automotive wire harnesses with that of IT and consumer electronics. The extent to which paradigms and technologies that may deviate from the current automotive state of the art can be borrowed from the IT and consumer product environment needs to be assessed.