Pedestrian protection: Actuators

The number of installed actuators for the pedestrian protection depends on the series and the engine version. Thus, there are vehicles with the following number of actuators for the pedestrian protection:

• without actuators in the engine compartment lid hinge (sufficient space available)
• 2 actuators only on the rear engine compartment lid hinge
• 4 actuators only on the front and rear engine compartment lid hinges

If a collision with a pedestrian is registered by the pedestrian protection system, the Crash Safety Module (ACSM) always triggers all the actuators for pedestrian protection. This triggering is pyrotechnical.

With spring force, the engine compartment lid is then raised by several millimeters at the front and rear. This enlarges the space between the inner panel of the engine compartment lid and the add-on parts to the engine as well as on the body. The enlarged space increases the possible deformable area of the engine compartment lid in the event of a head impact. Furthermore, the rigid connection of the engine compartment lid is changed into an elastic connection by the springs in the actuators. This enables improved energy dissipation when the head strikes the engine compartment lid.

Using the F01 as an example, the following actuators are described for the pedestrian protection system:

Pedestrian protection actuator on front left and pedestrian protection actuator on front right 

If the Crash Safety Module (ACSM) sends a trigger signal, the actuators trigger as follows: The ignition squib in the pyrotechnic component ignites the propellant charge. The pyrotechnic actuator contains an ignition squib whose propellant charge shifts a plunger with bolt to unlock the engine compartment lid catch.

After this unlocking, the engine compartment lid is raised within a few milliseconds by several millimeters (e.g. 30 millimeters) by the force of the springs in the engine compartment lid catch.

• Front left actuator for pedestrian protection

  The actuator is installed in the front left engine compartment lid catch.

  Fig 1: Identifying Crash Safety Module

  Courtesy of BMW OF NORTH AMERICA, INC.

Item	Explanation
1	Front-left engine compartment lid catch with integrated front left actuator for pedestrian protection
2	Plug connection for engine compartment lid contact switch
3	Plug connection for pyrotechnic component
4	Pyrotechnic component (contains ignition squib, propellant charge and plunger with pin to activate the mechanical unlocking)

• Front right actuator for pedestrian protection

  The actuator is installed in the front right engine compartment lid catch.

  Fig 2: Identifying Pyrotechnic Related Components

  Courtesy of BMW OF NORTH AMERICA, INC.

Item	Explanation
1	Front right bonnet catch with integrated front left actuator for pedestrian protection
2	Plug connection for pyrotechnic component
3	Pyrotechnic component (contains ignition squib, propellant charge and plunger with pin to activate the mechanical unlocking)

Actuator for pedestrian protection on rear left and actuator for pedestrian protection on rear right 

If the crash safety module sends a trigger signal, the actuators trigger as follows: The ignition squib in the pyrotechnic component ignites the propellant charge. The pyrotechnic actuator contains a ignition squib whose propellant charge unlocks the two retaining bolts in the lid. After this unlocking, the engine compartment lid is raised within a few milliseconds by several millimeters (e.g. 50 millimeters) by the force of the springs in the actuator.

• Rear left actuator for pedestrian protection

  The actuator is installed in the rear left engine compartment lid hinge of generation K2.

  Fig 3: Identifying Actuator For Pedestrian Protection

  Courtesy of BMW OF NORTH AMERICA, INC.

Item	Explanation
1	Rear left engine compartment lid hinge of generation K2.
2	Rear left actuator for pedestrian protection
3	Pyrotechnical component (contains priming cap, propellant charge and mechanical system for activating the locking pins)
4	Condensate drainage

• Rear right actuator for pedestrian protection

  The actuator is installed in the rear right engine compartment lid hinge of generation K2.

  Fig 4: Identifying Rear Right Actuator For Pedestrian Protection

  Courtesy of BMW OF NORTH AMERICA, INC.

Item	Explanation
1	Rear right engine compartment lid hinge of generation K2.
2	Rear right actuator for pedestrian protection
3	Condensate drainage
4	Pyrotechnical component (contains priming cap, propellant charge and mechanical system for activating the locking pins)