Neil Armstrong discusses how progression in electronics design is helping to reduce the weight of vehicles.
It is a never-ending quest for automotive manufacturers to reduce the weight of the vehicle. Delivering better fuel economy, higher payload capacity, longer battery life and better performance is the nirvana. So, how does the development and progression of electronics impact this mission?
The electronic functionality of modern commercial vehicles is increasing exponentially. The automotive electronics market is growing at a compound annual rate of over 7%. Today’s commercial vehicles have on average over 100 electronic control units (ECUs). Depending on the complexity of the vehicle and the functionality delivered, this figure can rise significantly. The drive towards electric vehicle technology or hydrogen power will inevitably push these numbers up. Common to most vehicles, electronics control the powertrain, gearbox, differentials, ABS, airbags, instrument controls, body functions, ADAS systems… the list goes on. The growth in the integration of additional electronic aids such as roll and stability control, side wind assist and load control is becoming commonplace. Irrespective of the electrical architecture, electronics need to be integrated to control these functions. Where they are located has some bearing on the electronic system weight. The balance for the designer is off-setting the number of electronic boxes to be distributed with the weight of additional, or reduced wire harnesses and interconnects.
The overall weight of vehicles is on the rise as additional functions are integrated. Of course, there is also continual drive from suppliers and sensor manufacturers to develop smaller and lighter components, along with a focused approach into lightweighting the electrical harness systems.
One route being taken to deliver less mass in the electronics is to integrate the component level designs into the mechanical plastic parts used in other areas of the vehicle, i.e. re-purposing plastic mouldings. Often referred to as In-Mould-Electronics (IME) this allows, to some level, low-complexity printed circuit board assemblies to be over-moulded through injection moulding techniques delivering electronic functionality without the need for a separate protective box. The limiting factor with this approach is that the stresses imposed by injection moulding can significantly limit the type and number of electronic components integrated in this way and mostly requires some level of smaller external box containing the main electronic control functions. This solution also renders the moulded unit non-recyclable as the very nature of the injection moulding process means that it is virtually impossible to recover the individual materials at end-of-life.
For over 25 years, In2tec has been pushing the boundaries in the design and delivery of flexible electronics, dedicating its resources to breaking down barriers in design to solve the most complex problems with pioneering technology solutions. In the case of electronic integration with plastic or composites, the company has taken a more elementary approach. Rather than moulding ‘in’ the electronics, In2tec utilises its Flexi-hibrid Electronic circuit board technologies and developed OMSE (On Mould Sustainable Electronics). “In simple terms, we take a circuit board manufactured on flexible or semi-rigid substrates and laminate it ‘onto’ sympathetically designed superstructures,” says Neil Armstrong, group managing director. Mark Hudman, chief technology officer at In2tec, adds, “This provides a far simpler single unit that can be moulded with traditional methods and integrates high complexity electronic circuits in an environmentally protected single element”.
Utilisation of real estate is the key value here. Integrating electronics onto superstructures within the vehicle significantly reduces the need for protective enclosures and in design can minimise the connector count. In addition, the ability to use areas of the vehicle not normally associated with electronics allows weight to be re-distributed and the centre of gravities lowered. For example, taking the seat control ECU (traditionally a plastic box with mechanical fixings housing the control and power electronics packaged primarily in the base of the seat system) and essentially dispersing the electronics onto a flexible substrate and laminating it to the internal seat back moulding reduces weight, and dramatically improves packaging constraints. It changes the whole paradigm of electronic integration and systemically engages both mechanical and electronic, or mechatronic design methodology providing a real synergy.
If we think about pushing the boundaries through innovation, Flexi-hibrid technologies can deliver planar interconnect systems (essentially flat wiring harness applications) with the electronic controls embedded in the wiring systems. Significantly reducing the number of connectors and the re-distribution of harness weight would revolutionise the advancement of traditional wiring harness design. Today, In2tec has already made possible printed flat shielded twisted pair designs through its patented technology, and low current transmission of power and data is delivered and demonstrated. A flat thermoformed wiring assembly with the CAN nodes integrated into the assembly provides a ‘stick and play’ approach to assembling the harness. “Full wiring systems delivering comms and power on flat formed surfaces is our end goal” states Hudman. “Just think if we can produce a wiring harness in the shape of a vehicle floor pan, adhere it simply onto the floor utilising all that real estate and doing so lowering the harness weight by over 40%. These are the predictions we have modelled.”
Electronics now has solutions to fully support and change the paradigms of electronics integration within the boundaries of automotive lightweighting, allowing designers to balance the additional functionality with minimising the weight increase. Maybe the lightweighting nirvana is closer than we think.
Neil Armstrong is managing director at In2Tec.
