Anton Dukart

A NON CONTACT STRAIN GAGE TORQUE SENSOR FOR AUTOMOTIVE SERVO DRIVEN STEERING SYSTEMS

Abstract Tapping of one or more torques (ranges 10 N m and 60 N m) on the steering column of an automobile for the purpose of servo control must satisfy both high accuracy requirements and high safety requirements. A suggestion for developing a low-cost solution to this problem is described below. Strain gages optimally satisfy both these requirements: however, for cost reasons, these are not applied directly to the steering column but to a prefabricated flat steel rod that is laser welded to the torque rod of the steering column. The measuring direction of the strain gages is under 45° to the steering-column axis. The strain gages are either vacuum metallized onto the support rod as a thin film or laminated in a particularly low-cost way by means of a foil-type intermediate carrier. The relatively low output signals of the measuring resistor bridge are amplified on site (on the steering column) with an integrated electronic evaluation circuit and converted into a frequency-analog, highly interference-proof signal. Neither collector rings nor cables are needed to connect the signal output and power supply to the fixed parts of the body. Both connections are made totally non-contact by means of a very simple and low-cost rotary transformer, which surrounds the steering column concentrically and has two separate winding chambers. In this case, it is practically impossible for air-gap fluctuations and similar interferences to falsify the frequency-analog measuring signal.

Weight sensing for the reliable deployment of the passenger airbag

Future passenger safety systems must ensure that there is an unequivocal classification of each passenger occupying a passenger seat. Corresponding legislative regulations mandate that, for babies in reboard seats and for infants with a weight of up to 33 kg, the airbags either do not deploy at all or deploy only incrementally. A classification to meet these requirements can be achieved by accurately determining the weight of each seated passenger. At Robert Bosch GmbH, a variety of load measurement bolts have been developed. After simulations of various types of bolts as well as the design of functional models and laboratory tests, a load measurement bolt with a Hall-IC was found to be the best solution. In a cooperation with the FH Cologne, this bolt was optimized for the application in vehicles.

Gewichtsmessung zur gesicherten Ausloesung des Beifahrer-Airbags

Fur zukunftige Insassenschutzsysteme im Pkw muss die Sitzbelegung des Beifahrersitzes mit unterschiedlich grosen Personen eindeutig klassifiziert werden konnen. Gesetzliche Vorschriften schreiben vor, dass bei Babys in Reboard-Kindersitzen und bei Kleinkindern bis zu einem Gewicht von 33 kg der Airbag entweder gar nicht oder nur noch gestuft gezundet werden darf. Eine solche Klassifikation kann uber die Erfassung des Sitzgewichts erfolgen. Bei der Robert Bosch GmbH wurden fur diese Aufgabe verschiedene Kraftmessbolzen entwickelt. Nach Simulationen von Bolzenvarianten, dem Aufbau von Funktionsmustern und Labortests hat sich ein Kraftmessbolzen mit Hall-IC-Abgriff als beste Losung herausgestellt. In einer Kooperation mit der FH Koln wurde dieser Bolzen fur den Kfz-Einsatz optimiert.