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PD ISO TS 19072 โ Road Vehicles Connection Interface for Pyrotechnic Devices, Two-way and Three-way Connections (Parts 3 & 4)
Road Vehicles โ Connection Interface for Pyrotechnic Devices, Two-way and Three-way Connections โ Parts 3 & 4 (BSI Published Documents, 2012)
๐ PD ISO/TS 19072 is a BSI Published Document covering the connection interface for pyrotechnic devices in road vehicles, with two-way and three-way connections. Pyrotechnic devices are widely used in automotive safety systems such as airbags (SRS), seatbelt pretensioners and battery disconnect devices, so the electrical reliability of their connection interface is critical to occupant safety. The series specifies the interface between the pyrotechnic device and the harness connector assembly; Part 3 covers type 1 connector assemblies and Part 4 covers type 2 connector assemblies, both prepared by BSI Technical Committee AUE/16 (electrical and electronic equipment) and published in 2012.
๐ก The defining difference between pyrotechnic device connectors and ordinary automotive connectors is safety: the connector must provide reliable short-circuit protection, mis-activation and mis-insertion prevention, so that the airbag is not inadvertently deployed or fails to deploy throughout storage, transport, assembly and service life.
1. Scope and General Framework ๐
PD ISO/TS 19072 applies to the connection interface between pyrotechnic devices in road vehicles (e.g. airbag gas generators, pretensioners, battery disconnect devices) and the vehicle wiring harness. It provides a unified interface specification for two-way and three-way connections; Part 3 (type 1) and Part 4 (type 2) define two widely used connector assembly structures. Part 3 supersedes the withdrawn DD ISO/TS 19072-3:2008.
| Part | Reference | Connector Type | Subject |
|---|---|---|---|
| Part 3 | PD ISO/TS 19072-3:2012 | Type 1 | Pyrotechnic device and harness connector assembly โ type 1 |
| Part 4 | PD ISO/TS 19072-4:2012 | Type 2 | Pyrotechnic device and harness connector assembly โ type 2 |
โ ๏ธ Type 1 and type 2 connectors have non-interchangeable mechanical and electrical interfaces. During selection and routing, the correct type must be chosen per the vehicle harness definition, and the match with the airbag/pretensioner initiator terminals must be confirmed to avoid poor contact or short-circuiting.
2. Dimensional Features and Performance Requirements ๐ง
A connector assembly typically comprises a retainer/mounting seat, a squib holder and a harness connector. The standard specifies the following:
- Mechanical dimensions: connector housing, terminal spacing, and mating dimensions and tolerances of retainer and squib holder.
- Electrical performance: contact resistance, insulation resistance, dielectric withstand and current-carrying capacity.
- Short-circuit protection: shorting-bar design across the terminals in the un-mated state, to prevent electrostatic or stray current from inadvertently firing the pyrotechnic device.
- Codings and polarization: different keyways/colour codings to prevent wrong or reverse insertion.
- Environmental robustness: temperature, vibration, humidity and chemical resistance requirements.
The connector-to-device mating must ensure contact reliability over the vehicle service life and allow quick, reliable insertion on the assembly line.
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Codings and polarization are a signature requirement of pyrotechnic device connectors: by combining mechanical keyways and electrical polarization, wrong or reverse insertion is prevented at the design level, eliminating ignition-circuit failures caused by incorrect wiring.
3. Key Design Points ๐ฉ
In engineering design, the pyrotechnic device connection interface should focus on the following:
- Airbag circuit short-circuit protection: in the un-mated state the ignition circuit is kept shorted via the shorting bar to prevent accidental firing; on mating the shorting bar opens and the ignition circuit is restored.
- Contact reliability: terminal material, plating and retention force must withstand vehicle vibration, shock and thermal cycling, keeping contact resistance stable over time.
- Connector Position Assurance (CPA): the connector should have a CPA mechanism so that full mating can be confirmed visually or by feel.
- EMC and immunity: the ignition circuit should resist vehicle electromagnetic interference to prevent false firing.
The standard also requires the connector assembly to have sufficient mechanical strength and sealing capability for use in different environments (engine bay and passenger compartment).
4. Testing and Verification ๐
Connector assemblies should be verified by a series of type tests: dimensional inspection, contact resistance and insulation tests, shorting-bar functional verification, insertion/withdrawal and retention force tests, vibration and shock tests, temperature cycling and damp-heat tests, and durability tests where applicable. Results should demonstrate stable electrical and mechanical performance over the vehicle life.
Because pyrotechnic devices are safety components, any connector failure can have serious consequences, so clear technical agreements between supplier and OEM should define acceptable test methods and acceptance criteria.
๐จ Testing pyrotechnic device connectors involves electric initiators and pyrotechnic charges; the test environment must comply with explosion protection and safety rules. Do not touch the ignition circuit unless authorised; use a dedicated dummy load and anti-static measures during electrical verification.
5. Engineering Practice Essentials ๐ ๏ธ
- ๐ Selection and matching: choose type 1 or type 2 per the vehicle harness definition, and verify terminal numbers, keyways and colour codings.
- ๐ง Assembly control: standardise assembly operations and CPA confirmation steps, preventing incomplete mating.
- ๐ Inspection and traceability: establish batch traceability and incoming inspection records, controlling key parameters such as contact resistance.
- ๐ Change management: any design change to the connector or initiator terminal must be re-validated and recorded.
6. Frequently Asked Questions โ
โ Q: Can type 1 and type 2 connectors be used interchangeably?
A: No. They have different mechanical and electrical interfaces; the correct type must be chosen per the vehicle definition, and mixing may cause poor contact or ignition-circuit failure.
A: No. They have different mechanical and electrical interfaces; the correct type must be chosen per the vehicle definition, and mixing may cause poor contact or ignition-circuit failure.
โ Q: Why does the connector need a shorting bar?
A: In the un-mated state the shorting bar keeps the ignition circuit shorted, preventing electrostatic or stray current from inadvertently firing the pyrotechnic device; on mating it opens to restore the circuit โ a necessary design for safety components.
A: In the un-mated state the shorting bar keeps the ignition circuit shorted, preventing electrostatic or stray current from inadvertently firing the pyrotechnic device; on mating it opens to restore the circuit โ a necessary design for safety components.
โ Q: What is the purpose of codings (polarization)?
A: Mechanical keyways and codings prevent wrong or reverse insertion, ensuring correct ignition-circuit connection at the design level.
A: Mechanical keyways and codings prevent wrong or reverse insertion, ensuring correct ignition-circuit connection at the design level.
๐ Q: Which tests verify connector performance?
A: Type tests include dimensional inspection, contact resistance and insulation tests, shorting-bar function, insertion/withdrawal and retention force, vibration and shock, temperature cycling and damp heat, and durability.
A: Type tests include dimensional inspection, contact resistance and insulation tests, shorting-bar function, insertion/withdrawal and retention force, vibration and shock, temperature cycling and damp heat, and durability.