Energy absorbing device

Claim 2

An energy absorbing device comprising at least one hydraulic jack having a cylinder, a piston slidable within said cylinder to enable displacement from a starting position toward a second position allowing the jack to compress under shock load, force exerting control means for providing a control force in proportion to the initial value of the pressure in the cylinder during initial jack compression, outlet conduit means for fluid expulsion during jack compression, and throttling means responsive to said control force for throttling the escape flow of hydraulic fluid from the cylinder along said conduit to maintain substantially constant pressure in said cylinder during substantially all the subsequent travel of said piston along said cylinder.

Claim 3

The energy absorbing device of claim 1, wherein said force exerting control means comprises a chamber, a conduit extending between said cylinder and said chamber, and said throttling means including a movable control valve member in said conduit connected to be subjected to the pressure of fluid contained in the chamber.

Claim 4

The energy absorbing device of claim 2, wherein said conduit includes a bore opening into said chamber and said valve member is slidably mounted in said bore, said valve member has one end face disposed to be subjected to the action of fluid in said chamber and an opposite end face which has a conical portion, and wherein said conduit includes a valve seat disposed to cooperate sealingly with said conical portion of said valve member.

Claim 5

The energy absorbing device of claim 2, additionally including a communicating conduit connecting the chamber to the cylinder of the jack, and a non-return valve in said communicating conduit allowing passage of hydraulic fluid only along a direction towards the chamber, said communicating conduit opening into the cylindrical wall of the jack cylinder in a position spaced a relatively small distance toward said second position from said piston when said piston is in said starting position so that said piston is capable of sufficient advance from said starting position to build up the maximum pressure in the cylinder before blocking off said communicating conduit.

Claim 6

The energy absorbing device of claim 2, aDditionally including a conduit passing through said valve member and connecting said jack cylinder to said chamber, and a non-return valve in said conduit allowing passage of fluid only in a direction towards said chamber.

Claim 7

The combination of the energy absorbing device of claim 1 and an automobile vehicle having a bumper and a chassis including an articulation connection at one end of said cylinder mounted on the vehicle chassis; a mobile assembly including a resilient metal leaf assembly secured to the vehicle bumper, said mobile assembly further comprising a first tubular member slidably mounted in the jack cylinder; a flanged edge at one end of said first tubular member forming a piston with an open working face; an inner tubular member integral with said first tubular member and disposed coaxially therein to form a hydraulic chamber and which has one end facing the cylinder; a valve seat edge at said one end of the inner tubular member; a longitudinally movable valve slidable in said inner tubular member and adapted to come into seating engagement with either said flanged edge of the first tubular member or the said valve seat edge of the inner tubular member; a longitudinal passage in the valve member; a non-return valve in said longitudinal passage; an evelope disposed around the first tubular member; and at least one orifice in the first tubular member communicating said envelope with the space between the first and inner tubular members.

Claim 8

The combination which claim 6, additionally including a plurality of said energy absorbing devices disposed between the vehicle chassis and bumper, and means connecting the space within the inner tubular member of one of said energy absorbing devices to the corresponding space of another of said energy absorbing devices.

Claim 9

The combination of claim 1, additionally including a plurality of said hydraulic jacks connected between a vehicle chassis and bumper; means connecting the cylinders of the jacks to a common control device which includes said force exerting control means and said throttling means; said common control device comprising a pressure chamber; a conduit communicating with said pressure chamber; a valve member slidably mounted in said conduit; a liquid reservoir; a passage arranged to communicate said jack cylinders with said reservoir, said valve member being effective to throttle the flow of liquid along said passage in response to pressure in the said chamber; a longitudinal conduit in said valve member; and a non-return valve in said longitudinal conduit for communicating said chamber with the jack cylinder.