Mounting system for a deceleration sensor

A mounting system for a vehicle deceleration sensor comprises a mounting bracket complementary to the housing of the deceleration sensor so as to accept the sensor in a slidable lost motion relationship.

BACKGROUND OF THE INVENTION 
Experience gained through crash testing a variety of vehicles has revealed 
that, in many vehicles and in many types of crash situations, the crash 
sensor detects the crash too late for optimum deployment of an inflatable 
occupant restraint system. Delayed sensing of the crash event may occur 
because the sensor is mounted too far away from the crush zone, or the 
crash pulse is attenuated or delayed because of the collapse of soft, 
front-end vehicle structures. The only way to avoid such delay is to mount 
the sensor in the crush zone, where the information about the crash 
arrives earliest. 
Analysis of vehicles after accidents indicates that the vehicle structure 
on which the sensor is mounted is often pushed back and/or rotated by the 
crash. Thus, conventional inertial sensors, such as ball-in-tube sensors 
or roller/spring sensors, when used in the crush zone, are subject to 
being destroyed or disconnected by the crash before they can signal the 
event 
One proposal to avoid the undesirable aspects of crush zone mounting is to 
replace inertial sensors with rugged switches which are closed by the 
impinging structure of the vehicle as it is pushed back by the force of 
the crash. Although this expedient works in some crash situations, it is 
limited by the fact that if the switch is not in the crush zone, the 
switch cannot detect the crash. For example, if the switch is mounted on 
body panels, it cannot detect, for example, the undercarriage of a vehicle 
hanging up on a low post or falling into a hole, in which situation the 
occupant would not be protected. 
SUMMARY OF THE INVENTION 
The object of this invention is a "lost motion" mounting bracket that 
facilitates the use of a rugged inertial sensor in the crush zone of a 
vehicle. The sensor, if involved in the crushing, moves back into its 
mounting bracket sufficiently to allow actuation of its internal 
mechanism. If the mounting location is properly chosen, such movement and 
actuation can take place before the vehicle structure bulkhead upon which 
the sensor is mounted is displaced or rotated due to the crash. 
If the sensor and mounting bracket are not directly involved in the crush 
zone, the normal inertial properties thereof effect actuation of the 
occupant restraint system because vehicle deceleration is transmitted to 
the inertial mechanism by the mounting bracket.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION 
As seen in FIG. 1, a cylindrical inertial sensor 10 is press-fit into a 
complimentary bracket 12 in tight but relatively slidable relationship. 
The sensor 10 protrudes forwardly of the bracket 12 so as to encounter 
folding or crushing of vehicle structure prior to the bracket 12. The 
bracket 12 is secured to a panel 14 of a vehicle (not shown) as by screws 
16. A pigtail 18 has an electrical connector 20 thereon which extends 
through an aperture 22 in the body panel for connection to a conventional 
airbag inflator (not shown). 
In the event of a crash that results in the impingement of the vehicle 
structure against the sensor 10, the sensor 10 is free to slide relative 
to the housing 12. The slidable lost motion connection of the sensor 10 to 
the housing 12 prevents the sensor 10 from being destroyed and ensures 
that sufficient deceleration is transmitted thereto for the internal 
mechanism thereof to operate prior to crush or rotation of the panel 14. 
While the preferred embodiment of the invention has been disclosed, it 
should be appreciated that the invention is susceptible of modification 
without departing from the scope of the following claims.