Unlocking system

An unlocking system is a system for releasing (unlocking) a force . The system is unlocked by means of activation energy in an energy converter. Electromagnets, pyrotechnics , pneumatic and hydraulic drives or manual power are used as energy converters .

Unlocking systems in automotive engineering

Locking and unlocking systems to protect against unauthorized use

Release systems for the rollover protection device of a convertible

Many modern convertibles have an active rollover protection device which, in the event of a rollover, can deploy a roll bar to protect the head area of the passengers in less than 150 milliseconds. The roll bars have very strong compression springs that raise the bar. In order to unlock the forces acting on the bars, electromagnetically driven unlocking systems are mostly used. With the introduction of the airbags in almost every modern motor vehicle, pyrotechnic actuators were also used as an energy source in the unlocking system.

Since the electromagnet has significantly lower forces than pyrotechnics, the acting spring force must be translated from the bracket by a mechanism in order to be switchable by the electromagnet. But even with pyrotechnics as an energy source, a translation is used to reduce the force.

The advantage of electromagnetic solutions is that they can be reversed, which means that the system can be checked and that repairs are not necessary in the event of incorrect tripping. The disadvantage is the mechanics necessary to translate the force, which have to be designed more complex than with a pyrotechnic solution.

The advantage of pyrotechnics is the significantly higher energy that is stored in the propellant, as well as the short release time. The disadvantage is that this safety system cannot be checked for functionality without destroying it. However, all pyrotechnic systems in motor vehicles have this disadvantage, for example airbags, belt tensioners, etc.