Accident data store

Accident data store

The invention relates to an accident data store according to the precharacterizing clause of Claim 1. The construction of accident data stores is known per se.

The purpose of an accident data store is to detect and record data which is useful for the objective clarification of the question of responsibility after an accident has occurred. It is part of the prior art to record the movement data and the state data of some vehicle units during the driving operation of a vehicle equipped with an accident data store. In the accident data store according to EP 0 118 818 Bl, the recording of data ends when the vehicle is at a standstill.

Conventionally, the event of an accident is detected at least by evaluating the acceleration signals which are detected by the accident data store. Since uneven roads, the normal driving dynamics or banging a vehicle door shut must not result in triggering of the memorizing procedures specially provided for an accident situation, the known accident data stores have triggering criteria which do not permit relatively minor bumps to be recorded. If a parked vehicle is driven into, for example during the manoeuvring of another vehicle, then an accident of this type cannot be recorded by the previously known accident data stores.

The object of the present invention is to eliminate this disadvantage. It is achieved by the characterizing features of the first claim. The other claims indicate advantageous further developments.

In accordance with the invention, it is proposed, in addition to the relatively high response thresholds required during the driving operation for triggering the memorizing procedures provided specially for non-deletable recording of an accident situation, to provide means which prolong the operational state of the accident data store after the drive unit of the vehicle has been switched off for a limited time, at an increased level of sensitivity for detecting and recording any events of accidents.

The sensitivity can be increased by reducing the threshold value of amplitude of the acceleration signals which is set for triggering the recording of an accident by about 90% at the same time as lengthening the period of monitoring of the duration of action of the acceleration signal which leads to triggering. Because the accident data store is expanded by means for carrying out this measure, even slight impacts can be detected in the parked vehicle.

In order to prevent erroneous triggering, it is useful to switch the accident data store over to this increased sensitivity only when the vehicle is at a standstill. To control the switching over, the accident data store requires the information as to the operating state of the drive unit of the vehicle. This, interrogation is preferably carried out by way of a detection of the switch position of the ignition start switch of the vehicle.

In order to avoid erroneous triggering directly after the drive unit of the vehicle has been switched off, which could be caused for example by the vehicle occupants leaving the vehicle or by unloading the vehicle, it is recommended to carry out the switching over to increased sensitivity with a time delay. A delay of approximately 5 minutes appears to be generally appropriate to practice. By this means it can be ensured that the vehicle is at rest.

So that findings about the event of an accident which are useful for an investigation can be made, it is advantageous to equip the accident data store which has been expanded in accordance with the invention with time counter means, so that the time of the accident can be determined precisely. The time counter means can be in the form of a real-time clock constructed as a complete calendar or merely as a relative-time meter. In either case, in this way a time mark can be stored in the recorded data set in addition to the impact data determined from the acceleration signals.