Crash Sensor

• US 20080315568A1
• Filed: 08/23/2005
• Published: 12/25/2008
• Est. Priority Date: 10/06/2004
• Status: Active Grant

• Current Assignee: Veoneer Sweden AB (SSW Partners LP)
• Original Assignee: Autoliv AB (Autoliv Incorporated)
• Inventors: Bergvall, Bengt Allan
• Granted Patent: US 7,836,998 B2
• Time in Patent Office: Days
• US Class Current: 280/735
• CPC Class Codes: B60R 21/0136 responsive to actual contact with an obstacle , e.g. to vehicle deformation, bumper displacement or bumper velocity relative to the vehicle monitoring crash strength in combination with passenger seat detection B60R21/01558

Abstract

A crash sensor comprising a support arrangement for supporting opposed ends of a yieldable element directly on one of an outer skin of a vehicle and a component adjacent to the outer skin with the yieldable element substantially parallel with the outer skin of the vehicle. A sensor arrangement in the form of resistors mounted on the yieldable element to generate a signal in response to deformation or bending of the yieldable element. A stiffness and a mass of the yieldable element is selected to achieve such that a period for a complete oscillation of the element at its resonance frequency is of at least 2 milliseconds.

Claims

1. An impact sensor for sensing an impact in a vehicle, the sensor comprising an elongate yieldable element and a support arrangement for supporting opposed ends of the yieldable element on one of an outer skin of the vehicle and a component adjacent to the outer skin of the vehicle, the yieldable element substantially parallel with the outer skin of the vehicle, wherein the yieldable element includes a sensor arrangement responsive to bending of the yieldable element that generates at least one signal in response to the yieldable element being bent, wherein the yieldable element has a stiffness and mass such that a period for a complete oscillation of the yieldable element is at a resonance frequency of at least 2 milliseconds.

2. An impact sensor according to claim 1 wherein the period for the complete oscillation is between 5 milliseconds and 20 milliseconds.

3. An impact sensor according to claim 1 wherein the support arrangement supports the opposed ends of the yieldable element that are spaced apart by a distance of at least 50 millimetres.

4. An impact sensor according to claim 1 wherein the support arrangement supports the yieldable element at spaced apart locations between 100 and 300 millimetres.

28. An impact sensor according to claim 2 wherein the impact sensor is mounted directly to the outer skin of the vehicle.

5. An impact sensor for sensing an impact in a vehicle, the sensor comprising an elongate yieldable element and a plurality of supports that support opposed ends of the yieldable element on one of an outer skin of the vehicle and a component adjacent to the outer skin of the vehicle, the yieldable element substantially parallel with the outer skin of the vehicle, wherein the yieldable element includes a sensor arrangement responsive to bending of the yieldable element that generates at least one signal in response to the yieldable element being bent, the supports respectively supporting the opposed ends being spaced apart by a distance of at least 50 millimetres.

6. An impact sensor according to claim 5 wherein the distance between the supports respectively supporting the opposed ends is between 100 and 300 millimetres.

7. An impact sensor according to claim 5 wherein the yieldable element has a stiffness and a mass such that a period for a complete oscillation of the yieldable element is at a resonant frequency of at least 2 milliseconds.

8. An impact sensor according to claim 5 wherein the impact sensor is mounted in the vehicle.

9. An impact sensor according to claim 5 wherein the impact sensor forms part of a strip wherein the strip includes a plurality of sensors substantially identical to the impact sensor.

10. An impact sensor according to claim 9 wherein the yieldable element is one of a plurality of elongate yieldable elements of the sensors in the strip of sensors.

11. An impact sensor according to claim 10 wherein the yieldable element has a weak mechanical coupling between adjacent sensors.

12. An impact sensor according to claim 11 wherein the weak mechanical coupling includes a plurality of cuts extending from opposite sides of the yieldable element.

13. An impact sensor according to claim 9 wherein the sensors comprise a plurality of resistors mounted on opposed faces of the yieldable element and a processor for processing the signals from the resistors.

14. An impact sensor according to claim 13 wherein each sensor includes one resistor on each side of a corresponding yieldable element, the resistors being connected to form a voltage divider connected to a source of potential, each sensor further including a tap connected to a junction between the resistors, the taps being connected to a processor.

15. An impact sensor according to claim 13 wherein each sensor is provided with two resistors on each side of the yieldable element, the resistors being connected to form a Wheatstone bridge.

16. An impact sensor according to claim 13 wherein each resistor is formed by a conductive track formed on one face of the yieldable element.

17. An impact sensor according to claim 5 wherein the yieldable element is a printed circuit board.

18. An impact sensor according to claim 5 wherein the yieldable element comprises a thermoset reinforced resin core and conductive tracks formed on each of two opposed faces of the core.

19. An impact sensor according to claim 5 wherein the supports are formed integrally with a tube, the yieldable element being mounted within the tube.

20. An impact sensor according to claim 5 wherein movement of a central portion of the yieldable element disposed between the supports is restricted in one direction such that complete oscillation is prevented.

21. An impact sensor according to claim 20 wherein a damping layer is located adjacent to a face of the yieldable element.

22. An impact sensor for sensing an impact in a vehicle, the sensor comprising an elongate yieldable element, and a support arrangement for supporting opposed ends of the yieldable element on one of an outer skin of the vehicle and a component adjacent the outer skin of the vehicle, the yieldable element substantially parallel with the outer skin of the vehicle, wherein the yieldable element includes a sensor arrangement responsive to bending of the yieldable element that generates at least one bend signal in response to the yieldable element being bent, the sensor arrangement including sensors that generate an output signal when the bend signal exceeds a threshold, wherein no output signal will be generated if the impacting speed is below a predetermined speed threshold or if the deformation of the outer skin is below a predetermined deformation threshold.

23. An impact sensor according to claim 22 wherein a natural period of oscillation of the yieldable element T₀ is approximately four times a period of time between an instant of impact and a latest possible instant corresponding to said speed threshold for generating the output signal.

24. An impact according to claim 22 wherein an output signal is generated in response to a movement of a central part of the yieldable element in excess of a bend threshold which is between about 3 and 30 mm.

25. An impact sensor according to claim 22 wherein the speed threshold is between about 15 and 60 kilometres per hour.

26. An impact sensor according to claim 22 wherein a free space of at least 5 millimetres is adjacent to at least one side of the yieldable element.

27. An impact sensor according to claim 22 wherein the impact sensor is mounted on an adjacent exterior portion of the vehicle.

29. An impact sensor according to claim 22 wherein the impact sensor is mounted to an internal reinforcing element, the internal reinforcing element being mounted immediately adjacent a skin of the vehicle.

30. An impact sensor system for sensing an impact in a vehicle, the impact sensor comprising an elongate yieldable strip, the strip comprising at least two elongate yieldable elements disposed along the strip, each yieldable element supported by a support arrangement at opposed ends of the yieldable element disposed directly on one of an outer skin of the vehicle and a component adjacent the outer skin of the vehicle, the yieldable element substantially parallel with the outer skin of the vehicle, wherein the yieldable strip includes at least one sensor arrangement, each sensor arrangement being responsive to bending of at least one of the yieldable elements such that at least one signal is generated in response to at least one yieldable element being bent.

31. An impact sensor system according to claim 30 wherein each yieldable element includes one of the sensors or sensor arrangements.

32. An impact sensor for sensing an impact in a vehicle, the sensor comprising an elongate yieldable element and a support arrangement including supports which are spaced apart by a distance of at least 50 millimetres to support opposed ends of the yieldable element directly on one of an outer skin of the vehicle and a component adjacent the outer skin of the vehicle, the yieldable element substantially parallel with the outer skin of the vehicle, the yieldable element including a sensor arrangement responsive to bending of the yieldable element such that at least one signal is generated in response to the yieldable element being bent, the yieldable element having a stiffness and a mass such that a period for a complete oscillation of the yieldable element is at a resonance frequency of between 5 milliseconds and 20 milliseconds, the sensor arrangement forming part of a strip which includes a plurality of substantially identical sensor arrangements, the yieldable element being included with a plurality of the elongate yieldable elements of the sensor arrangements in the strips, the yieldable element having a weak mechanical coupling between adjacent sensor arrangements, the weak mechanical coupling including a plurality of cuts extending from opposite sides of the yieldable element.