In order to reduce CO2 emissions, improve fuel efficiency, while enhancing the comfort and safety of the car, car manufacturers are now in the "car lightweight" in the direction of positive efforts. In recent years, designers of automotive wiring harnesses and connection systems have also been looking for solutions that can help them effectively reduce weight and feature integration.
With the increasing comfort, safety and economic requirements of the car, automotive electronic equipment is increasing to meet the expansion of system functions, but the car space is limited, while the car manufacturers to achieve energy saving and environmental protection The requirements, but also find ways to reduce the weight of the car. One of the main directions to resolve the contradiction is to design the parts as small as possible, to lay more parts in a limited space, and to control the overall weight. The trend also drives the associated connector design into the new technology era.
After years of efforts, TE Connectivity has successfully developed the next generation of miniaturized connectivity systems, including miniature connectors and terminals. TE Connectivity also offers innovative solutions and test verification methods for small wire diameter crimping problems developed by different wire manufacturers.
Development and Application of Small Wire Conduit
TE Connectivity research and development of small wire diameter, the biggest advantage is that it can significantly reduce the weight of the wiring harness, as shown in Figure 1 to 40 wires, for example, the diameter of 0.13mm2 the total weight of the wire only 0.5mm diameter wire 28 %.
At present, the major wire manufacturers have developed a variety of enhanced small diameter wire (see Figure 2), can be described as their own characteristics, the diameter has not yet formed uniform specifications. In the solution of small wire diameter drawing force on the issue of the application of a variety of innovative processes, such as the use of copper alloy wire, adding stainless steel wire.
Miniature connector connection system
The development of various small wire diameter wire has been accepted by the car manufacturers, in order to further reduce the connector provides a prerequisite. The 0.64mm terminal series developed by the miniaturized design of the mid-1990s was a general specification for the miniaturization of the current automotive industry. Typical products such as TE Connectivity's MQS terminals are widely used in 2.54mm pitch pairs Line and wire-to-board connection, with high density, reliable design, dual card lock and compact structure.
Now, the rapid increase in vehicle electronics drives drive further implementation of miniaturization, especially the high density and complexity of electronic devices requiring as much detail as possible in a limited space. As a result, TE Connectivity has further expanded the MQS product family and developed the next-generation miniaturization product, the KonMQS connectivity system. The series of terminals together with the plug and socket have been mass production, and used in the automotive field, very suitable for space compact and high vibration level of the environment, compared with the MQS terminal shape shown in Figure 3.
NanoMQS series in addition to reducing the weight of the terminal and jacket, the crimp wire diameter can reach a minimum of 0.13mm2. Standard version of the female terminal pieces made of copper alloy, with the public end of 0.5mm × 0.4mm rectangular needle. Silver-plated terminals can be used at ambient temperatures up to 170 ° C and can be used in the engine compartment. The terminal structure is shown in Fig.
In particular, the anti-vibration and impact resistance of automotive electrical connections is a key requirement. The LV214 standard defines the relevant test levels in the European region. According to this standard, the NanoMQS series of standard version can reach the second level (about 3g of random vibration and 30g impact). Although Level 2 is for the requirements of sealed products, however, the current non-sealed NanoMQS products also meet the requirements of this level, as shown in Figure 5, if the increase in the seal can reach the 3rd, 4th vibration level, Can be installed in the engine around or cabin, and even can be applied in the high vibration of the nozzle system.
From the size of the connector, the NanoMQS terminal hole spacing is 1.8mm. For the same number of board end plugs or sockets, only half of the MQS plugs are occupied, and the results are shown in Figure 6.
So compact structure, but also to find a smaller wall thickness, the injection molding process also put forward higher requirements, in fact, the product collection of a variety of high demand for the production process.
At present, NanoMQS series terminal plugs and sockets have been mass production, and used in the automotive field.
Small diameter of high reliability crimp verification
When the wire is getting smaller and smaller, the crimp quality of the wire has a great influence on the stability of the current transmission, especially the long-term use of the vehicle or the harsh conditions. After a long period of research, a harsh test standard, the "slow bending test", was proposed to assess the long-term reliability and stability of crimping parts under multiple conditions such as temperature shocks, wire harness circulation and temperature cycling. Has been part of the well-known car manufacturers as a mandatory requirement. The test principle is shown in Fig.
The "slow bending test" is divided into two steps:
(1) 100 cycles of temperature impact, the cycle period of 1h, which low temperature -40 ℃ and high temperature 125 ℃ for 30min each.
(2) harness clamping point every 15min movement time, the range of 25cm, a total of 720 cycles, lasted 180h. At the same time, the product experienced 30 temperature cycles, each cycle 6h.
N During the test, the amount of change in the crimp resistance is recorded. Before the test, the difference in crimp resistance between the samples was less than 1mΩ. After the test, the change of the crimp resistance value of each sample was less than 3mΩ. During the test, the change of the crimp resistance value of each sample was less than 3mΩ.