Deploying of pyrofuse, function - GF91.60-P-2011FL

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MODEL 212 Low-voltage pyrofuse

Function requirements, general

Circuit 15R ON

The status of circuit 15 is sent by the electronic ignition lock control unit (N73) up to 28.2.13 via chassis CAN (CAN E) or as of 1.3.13 via chassis CAN 1 (CAN E1) to the supplemental restraint system control unit (N2/10).

Deploying a pyrofuse, general

To avoid any possible fire hazard following a crash event, it is necessary to disconnect the starter (M1) and alternator (G2) quickly and reliably from the on-board electrical system.

Function sequence for triggering the pyrofuse

The central line to the starter and to the alternator is designed as busbar with predetermined fracture point (3) inside the pyrofuse housing. When a crash event occurs, the pyrofuse 150 (F32f150) in the front prefuse box (F32) is actuated directly by the supplemental restraint system control unit. When the pyrofuse is actuated, pressure builds up in the chamber (1). The piston (2) then moves against the predetermined fracture point disconnecting the bus bar.

Time sequence:

Piston movement starts after t = 300 μs

Line rail disconnection is finished after t = 450 μs.

Fig 1: Pyrofuse Deploying Function Diagram

Courtesy of MERCEDES-BENZ USA

Overview of system components for supplemental restraint system

GF91.60-P-9996FL