1. Field of the Invention
The invention relates to a method for manufacturing a bending sensor, in particular a strip-shaped bending sensor for an impact sensor device of a pedestrian protection system of a vehicle.
2. Description of the Related Art
Studies have shown that a high proportion of fatal accidents in road traffic involve pedestrians. For this reason, legislation initiatives are under way aimed at making the provision of devices for protecting pedestrians in the case of a collision with a vehicle compulsory in modern motor vehicles.
There is a particularly high risk of injury for a pedestrian when there is a collision between a vehicle and the distance between a typically easily deformable engine hood and a rigid engine block is very small. The arrangement of increasingly large numbers of electronic components in the region of the engine compartment and the fact that vehicles are of very compact design results in the engine compartment being tightly packed with very rigid elements. If a collision occurs with a pedestrian, there is therefore a high risk of severe head injuries if the pedestrian's head impacts against the engine hood and therefore comes into contact with the components located underneath the engine hood.
On the other hand, the risk of injury can be reduced greatly given a sufficiently large distance of, for example, over 10 cm between the engine hood and the engine components arranged underneath it, since the engine hood can absorb a sufficiently large amount of energy as a result of the deformation and can therefore brake the pedestrian's movement comparatively gently.
In order to increase safety of pedestrians in road traffic, the European Automobile Manufacturers' Association (ACEA), for example, has given a commitment to the authorities of the European Union to halve the number of traffic deaths involving pedestrians by the year 2010 by means of measures in vehicles. One measure for this purpose is to construct vehicles with correspondingly spaced engine hoods. However, this is frequently impossible due to the required compactness of vehicles.
In order to ensure sufficient attenuation in the event of a collision with a pedestrian, it has been proposed, if an impact of a person against the vehicle is detected, to raise the engine hood by more than 10 cm from its closed position in order to provide a sufficient area for deformation. The need for such safety systems to be not only reliable but also very cost-effective presents an enormous challenge for these systems.
For example, an article in the specialist journal “Automotive Engineer”, April 2004, page 48 ff., discloses, as an actuator for raising the engine hood, a spring-based actuator whose spring is prestressed and in the event of a detected collision is released, with the result that the engine hood is correspondingly raised. However, pyrotechnic actuators are also known from the abovementioned article.
CA 2 424 708 A1 discloses a method and a device for detecting a collision between a vehicle and an object. Lightguide fibers are arranged along a front bumper of the vehicle. The lightguide fibers comprise, in their fiber jacket, light exiting regions which are arranged along the lightguide fibers. A collision causes the lightguide fibers to bend. The attenuation of the light which is transmitted in the lightguide fibers changes as a result of the bending of the lightguide fiber if the lightguide fiber is bent in the light exiting region. A signal is acquired from the light which is modulated in this way and said signal is processed in a signal processor. A safety device, for example for raising an engine hood, can be activated in this way.