Fluid shock absorbing buffer

Claim 1

An energy absorbing device for a motor vehicle comprising: a bag adapted to be inflated instantaneously, said inflatable bag being folded in its inoperative condition in a cavity provided in at least one end of the vehicle and adapted to react against a reinforced portion of the vehicle structure, inflation means to inflate said bag upon receiving a signal from a detector, and obstacle detector means comprising at least one bumper disposed in a horizontal plane with an element extending across the end of the vehicle, a pair of longitudinal extensions engaging said bumper and a corresponding pair of recesses of the vehicle body, positioning means responsive to the velocity of translation of the vehicle adapted to extend or retract said extensions at a predetermined rate with said bumper being normally retracted at low vehicle speeds, means responsive to the reverse movement of said bumper with respect to the vehicle to cause the release of said inflatable bags when said movement exceeds a predetermined threshold corresponding to the engagement of an obstacle by the vehicle during the movement thereof, said positioning means for extending or retracting said bumper comprising a pump adapted to deliver hydraulic fluid under an adequate pressure, said pump being connected to a distributor of the type comprising a rotary core member for directing the fluid under pressure to one or the other end of a pair of double-acting cylinders mounted parallel to the longitudinal center line of the vehicle and having their pistons rigid with said longitudinal extensions of said bumper, said cylinders slidably engaged by said pistons having their ends responsive to the overpressure created by the inward movement of said bumper connected to a gauged pressure-responsive switch adapted in turn to monitor said inflatable bag release device whereby said device can be operated at any reverse movement of the bumper in its extended or operative position which is higher than the reverse movement corresponding to said gauged value of said pressure-responsive switch.