Land vehicles – Wheeled – Attachment
Reexamination Certificate
2001-04-27
2003-08-19
Morris, Lesley D. (Department: 3611)
Land vehicles
Wheeled
Attachment
C180S274000, C701S035000
Reexamination Certificate
active
06607212
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to sensors for detecting vehicle impact, for the deployment of air bags or other responses to a vehicle collision. The invention further relates to impact detection systems and vehicles incorporating same. In particular, the invention relates to a deformation sensor installed within the crush zone of a vehicle, which operates by sensing changes in intensity of light or other waveform energy, within a carrier medium, wherein the local intensity of the lighting increases in the event of deformation of the medium.
BACKGROUND OF THE INVENTION
Impact detection devices comprise an important element of the safety system of modern vehicles. The advent of air bags and automatic belt tighteners in particular have given rise to a need for accurate and responsive impact detection means. Desirably, detection means for vehicle use are relatively inexpensive. Further, it is essential that the sensors be highly reliable, and not be adversely affected by corrosion, temperature changes, altitude, etc.
Collision or impact sensors conventionally employ an accelerometer located in vehicle mid-body of the passenger compartment to detect rapid changes in vehicle velocity. However, these arrangements do not provide adequate information in respect of the location and severity of a collision event. The design and activation or increasingly sophisticated occupant restraint systems such as multiple air bags and seat belt tighteners render it important to sense the dynamics of an impact event in order to properly control the restraint devices. A greater degree of sensitivity and accuracy may be achieved through the use of crush zone sensors, which can be used to detect abrupt velocity changes within one or more of the impact zones of a vehicle. The crush zones are the regions within the vehicle which experience substantial deformation in the event of an impact, and which typically experiences a greater deceleration than the non-crush zone. The latter zone typically houses the passenger compartment. The crush zones typically comprise the trunk and engine compartments and the exterior regions of the door and side panels.
Conventional vehicle impact sensors include “ball-in-tube” sensors and “inertia” sensors. The ball-in-tube type sensor consists of a hermetically sealed housing, which encloses and surrounds a cylinder. A sensing ball-shaped piston is disposed within the cylinder, and the housing is filled with a damping gas. The piston includes electrically conductive elements. The piston resists movement within the cylinder, conventionally by means of a spring. When the device experiments a sufficient velocity change, the force experienced by the piston overcomes the countervailing bias exerted by the spring and displaces the piston within the cylinder. In addition to the force of the spring, the piston is also exposed to a damping force exerted by ambient damping gas, resulting from the pressure differential that exists once the piston has moved a specific distance within the cylinder. If the vehicle deceleration is sufficiently large in magnitude and long enough in duration to overcome both the damping force and the spring-biasing force, the piston will move to a position where contact is made with a circuit that will activate the air bag or other safety system.
An inertia type sensor operates on a similar principle, and comprises a moveable element, which is moveable relative to a static element. In one conventional version, an inertia sensor comprises a “rollamatic” type sensor, which comprises a nearly frictionless mechanism consisting of two or more rollers inserted within the loops of a flexible band, with the band acting to turn the rollers whose movement can be directed to perform various functions. The moveable element is held in place by the tension of the band and a surrounding housing. In the event of a collision or other sudden deceleration or acceleration, the resulting force displaces the moveable element. If the force is great enough in duration and magnitude, the moveable element will move a predetermined distance to a pin, which will be hit or dislodged, activating the air bag or other safety system.
Various other sensors have been proposed for use within crush zones, including simple electrical switches, electronic pressure switches, and rod and tube sensors. Conventionally, these sensors have been positioned at the outermost extremities of the crush zone. Other deformation centers have been described, particularly for lateral impact situations. These sensors detect either deformation extent of deformation velocity or, in some cases, a combination of both but with very limited resolution. In one aspect, sensors detect the extent of crushing of the vehicle itself as an indicator of the crash severity or velocity change. Such sensors conventionally initiate safety systems if the crush zone deforms to the extent that it makes contact with the sensor, which has been appropriately positioned within the vehicle. Typically, multiple deformation sensors are mounted at various locations within the vehicle.
Deformation sensors mounted within the vehicle crush zone conventionally operate by mounting a switch within the crush zone which when the vehicle experiences a sufficient impact, forces two elements of the switch together to create an electrical contact. For example, a fiber optic type switch may be mounted within the contact zone (See U.S. Pat. No. 4,988,862). Alternatively, two spaced apart conductors separated by an elastic member may be mounted within the crush zone, with the conductors contacting each other upon experiencing a sufficient impact. (See U.S. Pat. No. 4,995,639).
A further type of collision sensor is disclosed in Germany laid open application DE 4407763 A1 (Robert Bosch GmbH). This arrangement comprises a collision deformation sensor for mounting within the crush zone of a vehicle comprising first and second spaced apart substrates, each of which may be mounted to or comprise a corresponding vehicle component within the crush zone. Between the substrates, means are provided for detecting convergence of the substrates and to generate an electronic signal in response to the detected convergence. Means are also provided which are responsive to the electronic signal, for actuating an occupant restraint system. The detection means relies on a light guide, which becomes deformed when the substrates converge. Deformation of the light guide caused by crushing of the vehicle releases a portion of the light traveling through the guide out the side walls thereby attenuating the light intensity reaching the light detector.
None of these conventional arrangements are entirely suitable for detecting velocity changes within the crush zone of a vehicle in a manner suitable for sensing all or most potentially injurious accidents. In particular, inertial sensors have been found to trigger air bag restraint systems on short duration acceleration pulses, but not on longer duration pulses. As well, the ball-in-tube type sensor has had little success when responding to vertical and lateral acceleration, and only responds relatively well to longitudinal deceleration. Further, the ball-in-tube sensor may be adversely affected by temperature, with extremes of temperature adversely effecting the viscosity of the damping gas within the sealed housing.
A drawback within many prior art sensors resides in the risk of accidental triggering in response to a non-destructive or non-injurious impact. It is desirable to provide a deformation sensor which is integral to the primary structure of the vehicle and will with a high reliability not respond to any event other than an actual deformation of the structural and/or energy absorbing members of the vehicle. It is further desirable to provide a sensor that is highly reliable in adverse environments and relatively inexpensive to mass produce.
A drawback within many prior art sensors resides in the risk of accidental triggering in response to a non-destructive or non-injurious impact. It is desirable to pro
Baldwin Lorna H.
Reimer Ernest M.
Canpolar East Inc.
Lum L.
Morris Lesley D.
Spencer Fane Britt & Browne LLP
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