Lockable Piston-Cylinder Unit Preventing Buckling
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Solution Overview
Problem
Gas springs used for opening hatches or doors in motor vehicles experience buckling due to transverse forces generated by the pivoting of the fastening tube when overloaded.
Innovation Solution
The cylinder arrangement and fastening tube are arranged coaxially and rotatable relative to each other, with uniformly distributed supporting and counterstops to prevent buckling, and a mechanism for blocking rotation when the piston rod is not fully extended to ensure secure locking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fastening tube is pivoted between release position and locking position, then the piston rod can be locked in extended position, but transverse forces are generated causing buckling
Solution Approach 1:
Instead of pivoting the fastening tube to achieve locking, the invention inverts the approach by making the cylinder arrangement rotatable relative to the fastening tube. The fastening tube remains fixed while the cylinder arrangement rotates into locking position, eliminating transverse forces on the piston rod while maintaining the locking function through the rotational movement of the supporting stops relative to counterstops.
2Ease of operation
If the fastening tube is pivoted to lock the piston rod, then locking function is achieved, but the system becomes vulnerable to buckling under overload
Solution Approach 1:
The invention inverts the traditional locking mechanism by keeping the fastening tube fixed and allowing the cylinder arrangement to rotate instead. This inversion eliminates the harmful pivoting action that causes buckling while preserving the ease of operation through the rotational movement of the cylinder arrangement into the locking position.
Solution Approach 2:
The invention applies preliminary anti-action by designing the rotational locking mechanism to prevent buckling before it can occur. The coaxial arrangement and rotational movement are specifically designed to counteract the generation of transverse forces, providing preventive protection against buckling damage under overload conditions.
3Stability of the object's composition
If supporting stops and counterstops are uniformly distributed, then force distribution is improved, but manufacturing complexity increases
Solution Approach 1:
The invention applies universality by designing the supporting stops and counterstops to serve multiple functions: they provide locking engagement, distribute forces uniformly through their circumferential distribution, and guide the rotational movement. This multi-functionality is achieved with a relatively simple structure where the stops are uniformly distributed around the circumference, balancing manufacturing simplicity with force distribution uniformity.
Data Source
AI summary
A lockable piston-cylinder unit includes a cylinder having at least one axially facing counterstop; a piston dividing the cylinder into a first working chamber and a second working chamber; a piston rod extending through the first working chamber to a free end outside the cylinder; and a fastening tube having a first end in which the free end of the piston rod is fixed, a second end which receives the cylinder coaxially, and at least one axially facing supporting stop. When the piston rod is extended to maximum extension, the fastening tube is rotatable relative to the cylinder from a release position, wherein the supporting stop is offset from a respective counterstop, to a locking position, wherein the supporting stop faces the counterstop so that the fastening tube cannot move axially relative to the cylinder.