The paper presents a low-priced micromechanically produced limit value switch sensitive to accelerations. The main application areas are control systems for airbags. To control the side airbags it is necessary to achieve short response times. The advantage of the use of a micromechanical seismic mass coupled with a spring lies, for example, in that the system is electromagnetically compatible because there are no electronics necessary. It is difficult to dampen such system due to their high mechanical quality. This fact is very disadvantageous for sensor applications because due to this property the system oscillates and may cause wrong ignition. A free oscillation will be prevented through magnetic pre-stressed spring in the switch here presented. The switch is based on the magnetic reluctance principle and contains a spring coupled with a seismic mass. The magnetic field is generated by an integrated permanent magnet. The magnet and the switches form a closed magnetic circuit witch contains at least two air gaps: the contact gap and the sensitive air gap. The sensitive air gap changes depending on the acceleration. The consequence is a variation in the field strength in the contact gap. The switch closes when the magnetic field strength exceeds a limit value. The state of the switch is evaluated by the current flow. In standard operation it works without a current.
Micro-electro-mechanical acceleration-sensitive switch
Beschleunigungssensitiver Schalter in mikroelektromechanischer Bauweise
2001
7 Seiten, 3 Bilder, 2 Quellen
Conference paper
English
Micro-Electro-Mechanical Acceleration-Sensitive Switch
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