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More and more passenger cars are equipped with passive side protection systems such as thorax airbags for front and rear passengers. In the past, side airbag protection systems used sensors based on acceleration measurements [1]. In the meantime different sensor principles have been tested in order to increase the performance of this application. The intention has been to achieve faster firing decisions and to decrease the misuse risk for a floor or chassis impact. This paper presents the partitioning of an advanced chipset for pressure and acceleration based airbag systems. It shows the communication link between the sensors, the receiver-IC and other blocks in the application.

Sensing and acting elements to guarantee the locking functions of seat belt retractors can emit noise when the retractor is subjected to externally applied vibrations. For these elements to function correctly, stiffness, inertia and friction needs to be in tune, leading to a complex motion resistance behavior, which makes it delicate to test for vibration induced noise. Requirements for a noise test are simplicity, robustness, repeatability, and independence of laboratory and test equipment. This paper reports on joint development activities for an alternative test procedure, involving three test laboratories with different equipment. In vehicle observation on parcel shelf mounted retractors, commercially available test equipment, and recent results from multi-axial component tests [1], set the frame for this work. Robustness and reliability of test results is being analyzed by means of sensitivity studies on several test parameters.

Seatbelt retractors as important part of modern safety systems are mounted in any automotive vehicle. Their internal locking mechanism is based on mechanically sensing elements. When the vehicle is run over rough road tracks, the retractor oscillates by spatial mode shapes and its interior components are subjected to vibrations in all 6 degrees of freedoms (DOF). Functional backlash of sensing elements cause impacts with neighbouring parts and leads to weak, but persistent rattle sound, being often rated acoustically annoying in the vehicle. Current acoustic retractor bench tests use exclusively uni-directional excitations. Therefore, a silent 2 DOF test bench is developed to investigate the effect of multi-dimensional excitation on retractor acoustics, combining two slip-tables, each driven independently by a shaker. Tests on this prototype test bench show, that cross coupling between the two perpendicular directions is less than 1%, allowing to control both directions independently.

From an acoustical point of view, the integration of seatbelt retractors in a vehicle is a real challenge that has to be met early in the vehicle development process. The buzz and rattle noise of seat belt retractors is a weak yet disturbing interior noise. Street irregularities excite the wheels and this excitation is transferred via the car body to the mounting location of the retractor. Ultimately, the inertia sensor of the locking mechanism is also excited. This excitation can be amplified by structural resonances and generate a characteristic impact noise. The objective of this paper is to describe a simulation method for an early development phase that predicts the noise-relevant low frequency local modes and consequently the contact of the retractor with the mounting panel of the car body via the finite element method.

In the case of a side impact the decision to deploy an airbag has to be taken much faster as it would be required for a front impact. Furthermore, there is a significant spread of the measurable acceleration depending on which pillars of the cars side are hit. Measuring the pressure inside the door as a direct result of an impact, the deformation of the door becomes observable. Based on pressure measurements side impacts can be detected much faster and more reliable. Therefore side airbag pressure sensors are established as add-on or replacement for side airbag acceleration sensors. This paper will present a Side Airbag Chip Set comprising of a side airbag pressure sensor and a satellite receiver. The system architecture and the partitioning between a single chip solution for the side airbag pressure sensor module plus the compatible satellite receiver will be described.