초록 ▼

A positioning element to position two objects which are movable in relation to one another includes a cylinder in which there is an axially movable piston rod with a piston. The piston sealingly divides the cylinder into two working chambers by a piston ring, each of the working chambers containing

A positioning element to position two objects which are movable in relation to one another includes a cylinder in which there is an axially movable piston rod with a piston. The piston sealingly divides the cylinder into two working chambers by a piston ring, each of the working chambers containing blocking medium. The sealing by the piston ring can be bypassed during an insertion stroke of the piston rod. The piston includes a piston base body and a valve element, the valve element being movable along the base body to open and close a flow connection between the working chambers. An external opening force can displace the valve element to open the flow connection and permit an automatic extension stroke of the piston rod. The valve element remains open during the extension stroke on account of the flow of blocking medium through the flow connection. The valve element can be displaced to close the flow connection in response to stopping the extension stroke of the piston rod to position the two objects. To restart the extension stroke of the piston rod, a greater external opening force can be required than was necessary to start the initial extension stroke of the piston rod.

대표청구항 ▼

[ What is claimed is:] [1.] A strut for a motor vehicle for permitting moving and positioning and holding of one movable object with respect to another object, said strut comprising:a cylinder having a longitudinal axis;said cylinder comprising a first axial end and a second axial end;means for conn

[ What is claimed is:] [1.] A strut for a motor vehicle for permitting moving and positioning and holding of one movable object with respect to another object, said strut comprising:a cylinder having a longitudinal axis;said cylinder comprising a first axial end and a second axial end;means for connecting said cylinder to the one object;a piston rod having a first end and a second end;said first end of said piston rod being disposed within said cylinder;said second end of said piston rod extending out of said first end of said cylinder;means for connecting said second end of said piston rod to the another object;a piston being disposed within said cylinder;said piston being connected to said first end of said piston rod;said piston being disposed to divide said cylinder into first and second chamber portions;working fluid being disposed within said first and second chamber portions;a flow passage extending between said first chamber portion and said second chamber portion;said piston comprising a valve structure for opening and closing said flow passage between said first and second chamber portions;said valve structure of said piston comprising a first valve portion and a second valve portion;said first valve portion being disposed to be movable with respect to said second valve portion;said second valve portion comprising a portion of said flow passage;said portion of said flow passage being disposed within said second valve portion;said first valve portion comprising a cylindrical portion configured to be disposed in said portion of said flow passage within said second valve portion to close said flow passage;said cylindrical portion of said first valve portion being disposed to be movable in a first direction from said portion of said flow passage within said second valve portion to open said flow passage;said cylindrical portion of said first valve portion being disposed to be movable in a second direction toward said portion of said flow passage within said second valve portion to close said flow passage;said piston and said piston rod being disposed to be axially movable with respect to said cylinder to extend and retract said strut;said strut being extendable from a first position to a second position;said strut being further extendable from the second position to a third position;said strut comprising structure to permit said strut to selectively maintain a stationary position between the first position and the third position to hold an object and another object stationary with respect to one another;said cylinder comprising a first portion and a second portion;said piston being disposed within said first portion of said cylinder during an extension of said strut from the first position to the second position;said piston being disposed within said second portion of said cylinder during an extension of said strut from the second position to the third position;means for actuating said first valve portion to initiate movement of said cylindrical portion of said first valve portion in said first direction to open said flow passage;said means for actuating said first valve portion comprising a first surface upon said piston being disposed within said first portion of said cylinder;said first surface being disposed on said first valve portion;said first surface being disposed to transfer a force from said working fluid to said first valve portion;said first surface having a first cross section component;said first cross section component being disposed to accept a force substantially parallel to the longitudinal axis;said means for actuating said first valve portion comprising a second surface upon said piston being disposed within said second portion of said cylinder;said second surface being disposed substantially solely on said cylindrical portion of said first valve portion;said second surface being disposed to transfer a force from said working fluid to said first valve portion;said second surface having a second cross section component;said second cross section component being disposed to accept a force substantially parallel to the longitudinal axis;said first cross section component of said first surface is greater than said second cross section component of said second surface;said means for actuating said first valve portion being configured to hold said cylindrical portion of said first valve portion away from said portion of said flow passage in said second valve portion to keep said flow passage open until movement of said piston rod is stopped by an external force; andsaid means for actuating said first valve portion being configured to permit said cylindrical portion of said first valve portion to move towards said portion of said flow passage in said second valve portion to close said flow passage upon movement of said piston rod being stopped by an external force.