Modern engine design has resulted in higher operating temperatures. Meirion Buck, senior design & technical manager for Harnessflex, explains why conduit and fittings that support high temperature wiring and connectors that are vital in the drive for greater engine efficiency and performance.
The introduction of the Euro 6 and USA10 regulations have set some of the most stringent standards for emissions and have led to a growing number of engine design changes. The introduction and use of exhaust gas re-circulation (EGR), multiple and variable geometry turbocharging and diesel particulate filtration technologies have combined to create temperature hot spots within the engine bay, particularly near the EGR, injection and turbo systems.
Meanwhile, improved controls, sensors and system monitoring modules have created tightly packaged engines, making the protection of specialist high temperature cables, even more important.
One common solution is wrapping the wiring in heat reflective tape. While this acts as an effective heat shield, it can ultimately be expensive because of the amount of tape required and the potential need for reapplication during maintenance cycles. It also limits the flexibility of the cables which can impact and limit the layout of the system for a manufacturer. And taping doesn't offer protection for the connector, leaving it exposed and vulnerable to damage from vibration, impact and fluid ingress.
Conduit and fittings that cover both the cables and the connectors solve many, if not all, of the issues created by wrapping heat reflective tape. They not only provide the necessary protection from dirt, as well as pressure, steam and chemical cleaning but also relieve the strain on wiring to prevent disconnection or long-term issues. The Tempguard range from Harnessflex has been designed to protect high temperature cables from abrasion and ingress in temperatures up to 200°C, representing a temperature rating increase of more than 60% against the standard Harnessflex range.
Tempguard conduit and fittings are made from special co-polyester and polyamide that provide long-term heat, age, tensile and impact strength to protect vital cable connections. The system has survived long-term heat-age testing to ensure consistent performance when the correct high temperature wiring is used.
While supporting the higher engine temperatures and cables that manufacturers and harness makers now need to work with, there is also a clear market requirement for a full system solution which includes both conduits and matching fittings.
Specifying and installing a full system, provides the user with a complete high temperature wiring and cabling protection solution, helping to further reduce possible wiring failures. It also means that a bespoke solution can be developed in partnership with individual manufacturers to guarantee the best possible outcome for their specific engine. It was also important to ensure that the fitting and connectors of the Tempguard and standard ranges could offer a high back-stop and pull-off strength to guarantee a secure and reliable connection.
With the arrival of efficiency-led regulations and the on-going demand for higher performing vehicles that are also sensitive to noise levels, the automotive industry must now be taking the potential for high temperature issues seriously. Considering a complete conduit system, which covers both the high temperature cables and connectors, poses the ideal solution for compliance and improved performance.