Energy absorbing unit

Claim 2

In a hydropneumatic type energy absorbing unit including a cylinder tube subassembly and a piston tube subassembly disposed on said cylinder tube subassembly for relative telescopic collapse in an energy absorbing mode from a fully extended position and for automatic relative telescopic extension to the fully extended position, said energy absorbing unit further including a volume of working fluid adapted for throttled flow through a primary orifice during relative telescopic collapse of said piston tube subassembly, the improvement comprising, valve means disposed on said piston tube subassembly for movement between an open position during relative telescopic collapse of said piston tube subassembly and a closed position during relative telescopic extension oF said piston tube subassembly, and means on said valve means and on said piston tube subassembly operative in the closed position of said valve means to define a secondary orifice remote from said primary orifice for restricting the flow of said working fluid during relative telescopic extension of said piston tube subassembly thereby to retard the rate of said extension.

Claim 3

In a hydropneumatic type energy absorbing unit including a first tube, a second tube disposed on said first tube for relative telescopic collapse and extension, a fixed piston disposed on one end of said second tube and including an aperture therethrough, said first tube and said piston cooperating in defining a primary chamber for a working fluid adapted for flow through said aperture during relative collapse of said second tube, a free piston slidably disposed in said second tube defining a movable partition between a gas chamber and a secondary chamber for said working fluid, said secondary chamber receiving said working fluid during relative collapse of said second tube thereby to compress a gas in said gas chamber for effecting automatic relative extension of said second tube, and a metering pin rigidly attached to said first tube and projecting through said aperture for cooperation with the latter in defining a primary flow orifice for said working fluid, the improvement comprising, a valve member having a radially expandable aperture therein complementary in configuration to the cross-sectional configuration of said metering pin, means supporting said valve member on said fixed piston in said secondary chamber for relative reciprocation between a closed position covering said primary orifice and an open position exposing said primary orifice, said valve member in said expandable aperture slidably and sealingly receiving said metering pin so that said valve member is positively located in the closed position during relative extension of said second tube, and means defining a secondary orifice between said secondary chamber and said primary orifice with said valve member in the closed position for throttling the flow of said working fluid between said secondary chamber and said primary chamber during relative extension of said second tube thereby to retard the rate of said extension.

Claim 4

In a hydropneumatic type energy absorbing unit including a first tube, a second tube disposed on said first tube for relative telescopic collapse and extension, a fixed piston disposed on one end of said second tube and including an aperture therethrough, said first tube and said piston cooperating in defining a primary chamber for a working fluid adapted for flow through said aperture during relative collapse of said second tube, a free piston slidably disposed in said second tube defining a movable partition between a gas chamber and a secondary chamber for said working fluid, said secondary chamber receiving said working fluid during relative collapse of said second tube thereby to compress a gas in said gas chamber for effecting automatic relative extension of said second tube, and a metering pin rigidly attached to said first tube and projecting through said aperture for cooperation with the latter in defining a primary flow orifice for said working fluid, the improvement comprising, a valve member having a radially expandable aperture therein complementary in configuration to the cross-sectional configuration of said metering pin, means supporting said valve member on said fixed piston in said secondary chamber for relative reciprocation between a closed position covering said primary orifice and an open position exposing said primary orifice, said valve member in said expandable aperture slidably and sealingly receiving said metering pin so that said valve member is positively located in the closed position during relative extension of said second tube, and means defining a secondary orifice between said secondary chamber and said primary orifice with said valve member in the closed position for throttling the flow of said working fluid between said secondary chamber and said primary chamber during relative extension of said second tube thereby to retard the rate of said extension.

Claim 5

In a hydropneumatic energy absorbing unit including a first tube, a second tube disposed on said first tube for relative telescopic collapse and extension, a fixed piston disposed on one end of said second tube and including an aperture therethrough, said first tube and said piston cooperating in defining a primary chamber for a working fluid adapted for flow through said aperture during relative collapse of said second tube, a free piston slidably disposed in said second tube and defining a movable partition between a gas chamber and a secondary chamber for said working fluid, said secondary chamber receiving said working fluid during relative collapse of said second tube thereby to compress a gas in said gas chamber for effecting automatic relative extension of said second tube, and a metering pin rigidly attached to said first tube and projecting through said aperture for cooperation with the latter in defining a primary orifice for said working fluid, the improvement comprising, a plastic valve disc having a radially expandable aperture therein complementary in configuration to the cross-sectional configuration of said metering pin, means supporting said valve disc on said fixed piston in said secondary chamber for relative reciprocation between a closed position covering said primary orifice and an open position exposing said primary orifice, said valve disc in said expandable aperture slidably and sealingly receiving said metering pin so that said valve disc is positively located in the open position during relative collapse of said second tube and in the closed position during relative extension of said second tube, and means on said valve disc defining a plurality of passages adapted for effectiNg communication between said secondary chamber and said primary orifice with said valve disc in the closed position, said passages defining a corresponding plurality of secondary orifices for throttling the flow of said working fluid from said secondary chamber to said primary chamber thereby to retard the rate of relative extension of said second tube.

Claim 6

In a hydropneumatic energy absorbing unit including a first tube, a second tube disposed on said first tube for relative telescopic collapse and extension, a fixed piston disposed on one end of said second tube and including an aperture therethrough, said first tube and said piston cooperating in defining a primary chamber for a working fluid adapted for flow through said aperture during relative collapse of said second tube, a free piston slidably disposed in said second tube and defining a movable partition between a gas chamber and a secondary chamber for said working fluid, said secondary chamber receiving said working fluid during relative collapse of said second tube thereby to compress a gas in said gas chamber for effecting automatic relative extension of said second tube, and a metering pin rigidly attached to said first tube and projecting through said aperture for cooperation with the latter in defining a primary orifice for said working fluid, the improvement comprising, a plastic valve disc having a radially expandable aperture therein complementary in configuration to the cross-sectional configuration of said metering pin, means supporting said valve disc on said fixed piston in said secondary chamber for relative reciprocation between a closed position covering said primary orifice and an open position exposing said primary orifice, said valve disc in said expandable aperture slidably and sealingly receiving said metering pin so that said valve disc is positively located in the open position during relative collapse of said second tube and in the closed position during relative extension of said second tube, and means on said valve disc defining a plurality of passages adapted for effectiNg communication between said secondary chamber and said primary orifice with said valve disc in the closed position, said passages defining a corresponding plurality of secondary orifices for throttling the flow of said working fluid from said secondary chamber to said primary chamber thereby to retard the rate of relative extension of said second tube.

Claim 7

In a hydropneumatic energy absorbing unit, the combination comprising, a first tube, a second tube disposed on said first tube for relative telescopic collapse and extension, a fixed piston disposed on one end of said second tube and including an aperture therethrough, said first tube and said piston cooperating in defining a primary chamber for a working fluid adapted for flow through said aperture during relative collapse of said second tube, a free piston slidably disposed in said second tube and defining a movable partition between a gas chamber and a secondary chamber for said working fluid, said secondary chamber receiving said working fluid during relative collapse of said second tube thereby to compress a gas in said gas chamber for effecting automatic relative extension of said second tube, and a metering pin rigidly attached to said first tube and projecting into said aperture, said metering pin being of circular cross-section and cooperating with said piston aperture in defining a variable area primary orifice for said working fluid, a plastic valve disc having a radially expandable circular aperture therein and a plurality of grooves in each surface thereof extending radially between said circular aperture and the outside diameter of said valve disc, a perforated cage member, and means rigidly attaching said cage member to said fixed piston in said secondary chamber, said valve disc being floatingly disposed in said cage member and constrained by the latter for generally reciprocating movement relative to said fixed piston between a closed position covering said primary orifice and an open position exposing said primary orifice, said valve disc in said expandable aperture slidably and sealingly receiving said metering pin so that said valve disc is positively located in the open position during relative collapse of said second tube thereby to permit unimpeded flow of said working fluid from said primary orifice into said secondary chamber through said perforated cage and positively located in the closed position during relative extension of said second tube thereby to direct the flow of said working fluid through a corresponding plurality of secondary orifices defined by said grooves for throttling the flow of said working fluid to retard the rate of relative extension of said second tube.

Claim 8

In a hydropneumatic energy absorbing unit, the combination comprising, a first tube, a second tube disposed on said first tube for relative telescopic collapse and extension, a fixed piston disposed on one end of said second tube and including an aperture therethrough, said first tube and said piston cooperating in defining a primary chamber for a working fluid adapted for flow through said aperture during relative collapse of said second tube, a free piston slidably disposed in said second tube and defining a movable partition between a gas chamber and a secondary chamber for said working fluid, said secondary chamber receiving said working fluid during relative collapse of said second tube thereby to compress a gas in said gas chamber for effecting automatic relative extension of said second tube, and a metering pin rigidly attached to said first tube and projecting into said aperture, said metering pin being of circular cross-section and cooperating with said piston aperture in defining a variable area primary orifice for said working fluid, a plastic valve disc having a radially expandable circular aperture therein and a plurality of grooves in each surface thereof extending radially between said circular aperture and the outside diameter of said valve disc, a perforated cage member, and means rigidly attaching said cage member to said fixed piston in said secondary chamber, said valve disc being floatingly disposed in said cage member and constrained by the latter for generally reciprocating movement relative to said fixed piston between a closed position covering said primary orifice and an open position exposing said primary orifice, said valve disc in said expandable aperture slidably and sealingly receiving said metering pin so that said valve disc is positively located in the open position during relative collapse of said second tube thereby to permit unimpeded flow of said working fluid from said primary orifice into said secondary chamber through said perforated cage and positively located in the closed position during relative extension of said second tube thereby to direct the flow of said working fluid through a corresponding plurality of secondary orifices defined by said grooves for throttling the flow of said working fluid to retard the rate of relative extension of said second tube.