In recent years, the environment has deteriorated, the greenhouse effect has been strengthened, and the awareness of low-carbon life has sounded the alarm in people's hearts. Electric cars and hybrid cars with its environmental protection, energy-saving advantages of the popular favor. Automotive engineers forced the government policy guidance and industry competition pressure, increase the intensity of funds, from the automotive industry important electronic components automotive wiring harness, automotive connectors, power supply as the starting point, continue to develop the development of energy-saving environmentally friendly vehicles.
More environmentally friendly, lighter design
For today's automotive engineers, improving fuel economy and reducing greenhouse gas (GHG) emissions has become an important design guideline. It is clear that electric vehicles and hybrid cars are the solution to these challenges, but the technology to reduce the weight of the car can also provide some obvious benefits, because reducing vehicle weight and rolling resistance can reduce the demand for energy and effectively reduce carbon dioxide emissions The
In addition to improving component integration and the use of advanced materials to help car manufacturers reduce vehicle weight, wire harness weight is also a particularly interesting area and has attracted design engineers to re-examine their design to prevent automotive power Function is damaged due to high current fault condition.
One of the challenges for design engineers is to retain and / or increase circuit protection devices that help protect automotive electronics from possible overload conditions while reducing overall cost and weight. Since a car may usually contain hundreds of circuits and more than one kilometer of wire, the complexity of the cabling system may make the traditional circuit design technology difficult to use, and may lead to unnecessary over-design.
Many manufacturers have found that the use of distributed architectures and resettable polymer positive temperature coefficient (PPTC) overcurrent protection devices can significantly reduce vehicle weight. Figures 1 and 2 show the differences between traditional centralized architectures and distributed architectures. The centralized solution requires that each module be protected by a separate fuse in the junction box, see the yellow part of the figure. In this "star" architecture, each function also requires independent wires, thereby increasing the weight and cost. In contrast, in a distributed architecture where multiple junction boxes are powered by the power bus, each wire from the junction box can be protected by a resettable circuit protection device.
In the past, the mechanical strength specified in the car used the smallest wire diameter of 0.35 square millimeters (22 AWG), it can carry the current range from 8A to 10A. This limitation, to a certain extent, counteracts the benefits of using PPTC devices in low current signal circuits (such as below 8A). However, current wire material technology can support smaller diameter conductors under a given current carrying capacity, including wires with a diameter of 0.13 mm2 (26 AWB) and a maximum current of 5A. This advanced technology can reduce the weight when using distributed architecture and PPTC overcurrent protection.