A high-precision, high-reliability Renault 36-way harness connector has benefitted from DSM Arnite TV4 261 PBT
The number of features and functions of a modern car is constantly increas-ing. For years, gasoline consumption, environmental friendliness, comfort and passive safety have been the prime drivers of innovation by automobile manufacturers. This is rapidly changing, and now car manufacturers are also actively focusing on safety systems, hybrid vehicle powertrain and new bus structures. To rise to these new challenges, manufacturers of connectors have to strike an innovative chord. And as automakers deal with increasing complexities and the need to turn various functions of an automobile into a reliable working system, new grades of engineering plastics is finding their way in.
In a similar such development, a high-precision 36-way sectioning connector set for Renault automobile front/rear harnesses has benefited from the exceptional dimensional stability, high electrical insulating property and mouldability of Arnite polybutylene terephthalate (PBT) TV4 261 (30 per cent GF) resin from DSM Engineering Plastics. Designed and manufactured for Renault by FCI, a France-based designer and manufacturer of connector solutions for automotive, non-auto transportation, telecom infrastructure, micropackaging, consumer electronics, data storage, energy/power/utility, industrial instrumentation and medical sectors, the two-connector set incorporates many intricate geometric features for precise positioning and locking.
Arnite TV4 261 resin's balance of flow and mechanical properties helped enable the design of these complex parts using automated manufacturing equipment. The connector set is a standard component that fits many Renault vehicles manufactured after 2006, and including the Logan according to industry sources.
According to FCI engineers, connectors form an important interface in an modern automobile. An example of this, they add, is the interface technology AK-2, first introduced by FCI in 2004. It was the first airbag connector with 100 per cent scooproof mating contact protection and an optimized interface for assembling pyrotechnic applications like airbags or belt pretensioners. From start, two requirements of the automobile manufacturers had to be met: secure assembly of the interface, and increased ergonomics during assembly.
A typical step in car assembly is mating the connector into the retainer - the component accepting the connector in a one or multi-stage ignition mechanism for the airbag. For this step, the operatives in some assembly situations must be able to insert the connectors into the retainers more or less "blindly". Because of the previous designs of the interface this often led to broken contact parts in the airbag modules. As, however, this was discovered only in subsequent electrical functional tests, these failures caused great efforts to remove the affected vehicles out of the production line for required repairs. The key challenge lay in ensuring that the new development would fit in existing standard components with prescribed dimensions and attributes.
FCI solved the problem by using connector elements enclosed by a protective cylinder, which assured the reliability of the connector and its counter part as well as the right positioning of both components. Leading German automobile manufacturers have now selected this innovation as the future standard, and have published requirements accordingly. US automobile manufacturers, under the aegis of USCAR, have also recently decided to adopt this standard and are working out a USCAR specification to this effect, currently.
Safe mating is indeed an important issue when it comes to automotive connectors. Proper mating is extremely important to cut down on unreliable connections, which could be caused by vibration or increase in circuit resistance due to defective crimping of the terminal to wire. In the case of connectors for high-current highly critical applications for servo-assisted steering and hybrid drives, FCI has found a highly innovative way for assuring reliable mating. The company uses an RFID chip that has been integrated into the connector. As long as both halves of the connectors have not been joined up, the RFID chip doesn't send signals. As a result of the flange geometry of the connector, the RFID chip is activated as soon as the connector has reached its final snap-in position. This engineering solution was successfully tested with prototypes and can be implemented in varied device types.
RFID technology has other advantages. An RFID chip read by a stationary terminal or an assembly operator with a mobile terminal can not only inform that a connection has been fully plugged, it also forwards the following data to a database: the part number of the plug connector, the time at which the assembly operation was carried out, and the allocation to the correct cable harness, and/or any other tracing information that is enabled by the read/write characteristics of the memory chip. These represent an important contribution to problem tracking, should any malfunction occur later.