Hitachi Cable for Hybrid Electric Vehicles and Electric Vehicles

Recent years have seen strong demand to reduce the environmental impact associated with motor vehicles. Various countries around the word have sought to reduce carbon dioxide emissions to help fight global warming, strengthening fuel consumption requirements and emissions restrictions as part of this effort. Expectations are growing for next-generation electric vehicles that use electric motors in their drive trains, including standard hybrid electric vehicles (HEVs) that use both engines and electric motors, plug-in HEVs charged from commercial AC power supply, and electric vehicles that run on electric energy alone.

The drive systems of these electric vehicles consist of electric motors, inverters, batteries, and AC and DC harnesses connecting these electrical devices. Given the limited space for wiring and high-temperature conditions inside engine compartments, these harnesses must provide outstanding high-temperature resistance and flexibility. Used in numerous vehicle models, the power harnesses developed by Hitachi Cable include cables made of Fluonlex*2 fluorine resin, a material that confers superior heat resistance and flexibility, and halogen-free, heat-resistant cables offering improved heat resistance (capable of withstanding temperatures up to 150°C) through unique compounding technologies.

As Hitachi Cable’s harnesses have accumulated a performance track record, demand has grown for even smaller power harnesses. In response, Hitachi Cable has applied its own unique designs to develop the world’s smallest connectors for the power harnesses used in next-generation electric vehicles.

While most traditional connectors are configured so that a male terminal is inserted into each female terminal with a built-in spring, both male and female terminals in the newly developed compact connector are flat. This simple, unique structure allows a single spring to apply surface pressure to multiple terminals and reduces the connector volume by more than 40%, compared to previous Hitachi Cable connectors.*3 In addition, this lineup of connectors includes two variations—one using extending cables and one using a bus bar—allowing customers to choose the type of connection they prefer between the male connector and the electric device.

The connector also uses a structure in which spring force is applied after inserting the connector, facilitating connections and achieving high vibration resistance (181 m/s2 under the ISO 16750-3 standard) through increased spring pressure. This in turn promotes stable electrical performance, even under conditions of severe vehicle vibration.

Combining this newly developed connector with Hitachi Cable’s remarkably heat-resistant, flexible cables makes it possible to design harnesses that can be installed in narrow spaces and that are even easier to handle than previous models. The new connector will be compatible with cable conductor sizes ranging from 15 mm2 to 40 mm2.

Hitachi Cable plans to expand this area of its business while pursuing development activities to increase harness performance, thereby contributing to further advances in next-generation electric vehicles.

*1: The world’s smallest connector for use in power harnesses for hybrid electric vehicles and electric vehicles, as of June 28, 2011 (based on Hitachi Cable research).

*2: Fluonlex is a registered trademark of Hitachi Cable, Ltd. in Japan.

*3: Based on a comparison of the newly developed compact connector (extending cable type) to traditional Hitachi Cable connectors. For example, a traditional connector for cable conductors of 15 mm2 would have volume of 300 cc. The new compact connector measures 168 cc.