Electrical transmission or interconnection systems – Vehicle mounted systems – Automobile
Reexamination Certificate
2000-03-13
2001-08-14
Fleming, Fritz (Department: 2836)
Electrical transmission or interconnection systems
Vehicle mounted systems
Automobile
C307S121000
Reexamination Certificate
active
06274948
ABSTRACT:
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The invention relates to a device for protecting vehicle occupants in a motor vehicle.
International Publication No. WO 96/09942 A has an impact sensor which is located in a front area of a motor vehicle. A control unit is provided in a central area of the motor vehicle for controlling a vehicle occupant protection device. The impact sensor either has a plurality of mechanical acceleration switches which are sensitive to different accelerations and which supply a switching signal when a defined acceleration is exceeded. Alternatively an acceleration sensor which supplies an analog acceleration signal is provided as an impact sensor. The switching signals and/or the analog acceleration signal are supplied to the central control unit. The vehicle occupant protection device is triggered by the control unit if a signal of an acceleration sensor which is provided centrally with the control unit has a predefined profile, wherein this signal of the centrally located acceleration sensor is evaluated in a processor of the control unit. Individual operating states of the vehicle occupant protection device, such as individual stages of an airbag, for example, are subsequently selected as a function of the signal of the impact sensor.
When an electronic acceleration sensor is used as an impact sensor, interference variables acting on the line between the impact sensor and control unit can considerably falsify the sensitive analog signal which is supplied by the impact sensor. On the other hand, an extremely large amount of computational power has to be made available in the processor of the control unit to evaluate the analog signal. The need for such a large amount of computational power in the central processor is disadvantageous insofar as the processor has to cope with a large number of further computationally intensive functions such as evaluating signals of centrally disposed acceleration sensors or else also evaluating signals of other devices which are connected to the control unit, such as a device for detecting vehicle occupants and/or a child's seat. When mechanical acceleration switches are used as impact sensors, a relatively large signal-to-noise ratio is obtained when the switching signals are transmitted. However, such acceleration switches are complex components which are cost-intensive to manufacture and in particular do not permit precise evaluation of the timing of the acceleration acting on the front area of the vehicle.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a device for protecting vehicle occupants in a motor vehicle which overcomes the above-mentioned disadvantages of the heretofore-known devices of this general type and which, despite a low level of expenditure, can still provide an evaluation of the accident with a high resolution.
With the foregoing and other objects in view there is provided, in accordance with the invention, a device for protecting vehicle occupants in a motor vehicle, including:
a data line;
an impact sensor unit to be disposed in a front region of a motor vehicle, the impact sensor unit including an impact sensor for supplying an impact sensor signal, a first interface for outputting a code signal on the data line and a first evaluator for evaluating the impact sensor signal and generating the code signal as a function of the impact sensor signal if one of the impact sensor signal and an impact signal
derived from the impact sensor signal reaches a given value within a given time period;
a vehicle occupant protection device;
a control unit to be disposed in a central region of the motor vehicle, the control unit being connected to the impact sensor unit via the data line and being connected to the vehicle occupant protection device, the control unit having a second interface for receiving the code signal, an acceleration sensor for supplying an acceleration signal and a second evaluator for evaluating the acceleration signal and for controlling the vehicle occupant protection device as a function of the acceleration signal and of the code signal.
The impact sensor provided in the front part of the motor vehicle is assigned an evaluator—preferably in the form of a microprocessor with associated memory devices or in the form of an integrated circuit configuration—and an interface. The impact sensor, the assigned evaluator—referred to below as remote evaluator—and the interface form an impact sensor unit which is preferably provided as an electrical control device in a housing. The remote evaluator is provided for the impact sensor signal which is supplied by the impact sensor. A code signal is supplied by the impact sensor unit to the central control unit via the interface as a function of the evaluation of the impact sensor signal. An interface for receiving the code signal is provided in the central control unit. In addition, the central control unit has an acceleration sensor and an evaluator for an acceleration signal which is supplied by the acceleration sensor. The vehicle occupant protection device, which is assigned to the device according to the invention, is controlled by the evaluator of the control unit, referred to below as central evaluator. The central evaluator is preferably embodied as a microprocessor with associated memory devices, and controls the vehicle occupant protection device as a function of the evaluated acceleration signal and of the code signal. The acceleration sensor and impact sensor are in particular configured to detect a head-on collision.
The device according to the invention has the advantage that the central control unit does not have to make available any excessive computational power. This has, in particular, the advantage that when existing central control units without a remote impact sensor are expanded by providing just this impact sensor, only the software of the existing central control unit, but not its hardware, has to be changed. The central control unit is not flooded with analog signals which have to be discretized or quantized before being processed further. Only selected code signals with a relatively low throughput rate are transmitted to the central control unit by the remote impact sensor unit. On the other hand, despite the relatively small computational power of the central control unit, it is not necessary to dispense with the use of a remote electronic acceleration sensor and its information in the analog impact signal.
With the device according to the invention, it is possible to detect an impact extremely early. The impact sensor already supplies a significant impact sensor signal here at a time at which, for example, the centrally provided acceleration sensor still does not register an impact. It becomes possible to estimate the further course of the accident, and thus the forces acting on the vehicle occupant and also the forward displacement of the vehicle occupant, at an early time, with the result that it becomes possible to trigger the airbag appropriately.
According to advantageous embodiments of the invention, the remote evaluator performs at least the discretization or analog/digital conversion of the analog impact sensor signal. Here, the resolution of the converter may preferably be selected to be greater than seven bits, in which case digital code signals with discretized values are transmitted at time intervals approximately between 0.01 and 1 millisecond. However, the measured impact sensor signal is also preferably processed in such a way that it is filtered and/or integrated. Such an impact signal can be derived in some other way from the registered or detected impact sensor signal, for example by forming average values over short time intervals, by including past values from the impact sensor signal or the like. In this way, an impact signal is determined which is as free as possible of interference influences and is as reliable and meaningful as possible with respect to the impact at the front area of the vehicle. Here, the impact signal can be derived from the impac
Blank Thomas
Garcia Emmanuel
Heiser Markus
Leirich Oskar
Fleming Fritz
Greenberg Laureence A.
Lerner Herbert L.
Siemens Aktiengesellschaft
Stemer Werner H.
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