Diagnostics for vehicle deformation sensor system

Details Diagnostics for vehicle deformation sensor system Diagnostics for vehicle deformation sensor system

1998-10-23

2001-03-20

Lefkowitz, Edward (Department: 2736)

Communications: electrical

Land vehicle alarms or indicators

Internal alarm or indicator responsive to a condition of the...

C340S436000, C340S665000, C280S734000, C280S735000, C701S045000, C702S141000

Reexamination Certificate

active

06204756

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to sensors employed to detect vehicle impact events and more particularly to sensors mounted about portions of a vehicle in order to detect vehicle impact events and diagnostic systems to monitor the sensors.
BACKGROUND OF THE INVENTION
Almost all vehicles presently produced include some type of a passive restraint system to protect vehicle occupants, or others, during a vehicle impact event. Such passive restraint systems may include, for example, front and side airbags within the passenger compartment, seat belt pretensioners, and pedestrian airbags near the front of a vehicle. In order for the passive restraints to operate quickly when needed, and only when actually needed, sensor systems must be mounted on the vehicle to determine the severity and type of impact and actuate the proper passive restraint devices.
Some types of sensors used for impact measurements on vehicles approximate or infer the type of impact being experienced. Such sensors may be, for example, accelerometers, pressure sensors and crush-zone switches. While they can work adequately, it is desirable to improve the discrimination ability of vehicle impact sensing systems thus improving the passive restraint deployment decision upon vehicle impact.
Accelerometers, when used alone, may require very complex computer algorithms in order to properly distinguish various impact events. Pressure sensors have also been suggested, but may be too susceptible to changes to the surrounding vehicle environment. Further, simple switch contacts around the vehicle perimeter may be used but give little information regarding the intruding object's profile and/or velocity, making passive restraints deployment decisions difficult. Consequently, a desire exists to provide for more accurate sensing that will allow for discrimination between different types and severities of vehicle impact events to provide improved passive restraint actuation decisions, within minimal time frames. Further, a diagnostics system is desirable that will monitor the sensors to assure proper operation.
SUMMARY OF THE INVENTION
In its embodiments, the present invention contemplates a method of diagnosing a malfunction in an impact sensor including a multilayer sensor cable mounted along a component in a vehicle, the method comprising the steps of: generating a first diagnostic signal having a predetermined voltage and frequency; transmitting the first signal to a first location of the sensor cable; capacitively receiving a second diagnostic signal at a second location on the sensor cable, spaced from the first location; transmitting the second diagnostic signal to a controller; and analyzing the second diagnostic signal in the controller.
The present invention further contemplates a diagnostics system for diagnosing a malfunction in an impact sensor mounted in a vehicle. The diagnostics system includes a coaxial piezoelectric cable mounted along a component in a vehicle, means for generating a first diagnostic signal having a predetermined voltage and frequency, and means for transmitting the first signal to a first location of the piezoelectric cable. The system also includes means for capacitively receiving a second diagnostic signal at a second location on the coaxial cable, spaced from the first location, a controller for receiving the second diagnostic signal, and means for analyzing the second diagnostic signal.
Accordingly, an object of the present invention is to employ a piezoelectric cable mounted to structural members of a vehicle to discriminate between different impact events and provide a signal used to determine deployment of passive restraints within a vehicle.
Another object of the present invention is to provide a diagnostics system for the sensor cable to assure proper operation over the life of the vehicle.
An advantage of the present invention is that the piezoelectric cable sensor can be employed in combination with one or more acceleration sensors in order to further improve the passive restraints deployment decision.
A further advantage of the present invention is that the piezoelectric cable provides a variable output that is used to discriminate between various impact situations, thus improving passive restraint deployment decisions.
Another advantage of the present invention is that the piezoelectric sensor cable is mounted within a protective housing that will prevent inadvertent signals from actuating passive restraints due to non-impact events such as a vehicle door being slammed, etc.
A further advantage of the present invention is that the diagnostic check is employed without interfering with the sensor impact signal to assure that the piezoelectric sensor system is operating properly, while also assuring proper control of the passive restraints, as the vehicle ages.


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