Omni-directional crash sensor

• US 20050109075A1
• Filed: 07/30/2004
• Published: 05/26/2005
• Est. Priority Date: 01/16/2003
• Status: Active Grant

• Current Assignee: Methode Electronics Incorporated
• Original Assignee: Methode Electronics Incorporated
• Inventors: Rocher, Daniel J. Du, Kithil, Philip W., Novak, James L.
• Granted Patent: US 7,475,587 B2
• Time in Patent Office: Days
• US Class Current: 73/12.90
• 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
• CPC Class Codes: G01L 1/16 using properties of piezoelectric devices
• CPC Class Codes: G01L 5/0052 measuring forces due to impact G01L5/0061, G01L5/14 take precedence; impact testing of structures G01M7/08; impact testing of material G01N3/00

Abstract

A stress wave sensor comprising a piezoelectric film and means therein for connection to sensor electronics. The piezoelectric film preferably comprises polyvinylidene fluoride. Also a stress wave sensor system and methods employing one or more such stress wave sensors, preferably attached to a vehicle transparent component, most preferably to the vehicle windshield.

Claims

1. A stress wave sensor comprising a piezoelectric film and means therein for connection to sensor electronics.

2. The stress wave sensor of claim 1, wherein the piezoelectric film comprises polyvinylidene fluoride.

3. A stress wave sensor system comprising one or more stress wave sensors according to claim 1, wherein one or more of said sensors are attached to a vehicle transparent component, preferably to the vehicle windshield.

11. The stress wave sensor of claim 1, wherein the piezoelectric film includes a pollywog shape with tabs.

12. The stress wave sensor of claim 11, wherein the tabs are sputtered on opposite sides with conductive material.

13. The stress wave sensor of claim 11, wherein on one side, an outer edge of the sensor is masked.

14. The stress wave sensor of claim 11, wherein the tabs include at least two slots to allow crimp-thru connections to the sensor electronics.

15. The stress wave sensor of claim 11, wherein the connection means includes flexible circuit board material.

4. An impact detection system comprising a plurality of stress wave sensors each comprising a piezoelectric film, said system optionally comprising one or more accelerometers, wherein each stress wave sensor is attached to a vehicle skin, structural, or transparent component, and preferably to a transparent component.

5. The impact detection system of claim 4, wherein each stress wave sensor comprises polyvinylidene fluoride.

6. A method of characterizing a vehicle crash condition by reference to output from a plurality of sensors each comprising a piezoelectric film, the method comprising the steps of collecting output from the plurality of sensors;

and analyzing one or more of the group consisting of;

one or both of amplitude and rise time of each sensor'"'"'s output;

each sensor'"'"'s output in a plurality of frequency bands, preferably from at least bands at approximately 1 kHz-2.5 kHz and 5 kHz-20 kHz; and

time differentiated outputs of the sensors.

7. The method of claim 6, wherein the piezoelectric film comprises polyvinylidene fluoride, and optionally wherein the plurality of sensors are attached to a vehicle transparent component.

8. The method of claim 6, wherein the analyzing step comprises estimating either or both of a vehicle crash origin point and a crash severity.

9. A method of filtering crash events from non-crash events by comparing a response of one or more piezoelectric film sensors located on a transparent portion of a vehicle to a response of one or more piezoelectric film sensors not located on a transparency portion, and optionally employing the steps of the method of claim 6.

10. A vehicle windshield comprising a crash sensing system comprising one or more piezoelectric stress wave sensors positioned in or on the vehicle windshield.