Switch Point Coupling Assembly Reducing Fretting via Pivot Joint
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Solution Overview
Problem
Traditional coupling assemblies for switch point blades are prone to fretting and surface wear, leading to premature breakage, and fail to adequately compensate for thermal expansions and mounting errors, resulting in excessive tensional states and reduced reliability.
Innovation Solution
A coupling assembly featuring a tie rod with longitudinal and orthogonal slots, a rotatable pivot, and a plastic nut with a cylindrical coupling, allowing for 'washing' of residues and increased degrees of freedom to compensate for thermal and mounting variations, reducing tensional states and fretting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a traditional coupling assembly with rigid connection is used, then the structure is simple, but fretting and surface wear occur leading to premature breakage
Solution Approach 1:
The patent applies the dynamics principle by introducing a pivot joint that allows rotational movement between the tie rod and leg. This dynamic connection enables the assembly to adapt to thermal expansions and mounting errors while reducing fretting through controlled relative motion, thereby improving reliability without significantly increasing structural complexity
Solution Approach 2:
The patent changes the connection parameter from rigid fixed connection to rotational pivot connection. This parameter change allows the coupling assembly to accommodate dimensional variations and thermal effects, reducing contact stress and preventing the fretting that occurs in rigid connections
2Ease of manufacture
If a rigid connection between tie rod and leg is used, then manufacturing is simple, but thermal expansions and mounting errors cause excessive tensional states
Solution Approach 1:
The pivot joint introduces dynamic flexibility to the otherwise rigid connection, allowing the tie rod and leg to rotate relative to each other. This enables the assembly to compensate for thermal expansions and mounting errors, reducing excessive tensional states while maintaining manufacturing simplicity
Solution Approach 2:
The rotational degree of freedom provided by the pivot joint acts as a pre-cushioning mechanism, absorbing the effects of thermal expansion and mounting misalignment before they can cause excessive stress concentration, thereby protecting the assembly from premature failure
3Stability of the object's composition
If a closed connection structure is used, then structural integrity is maintained, but residues and dirt remain trapped accelerating wear
Solution Approach 1:
The rotational movement enabled by the pivot joint creates a dynamic connection that prevents residue accumulation. The relative motion between components allows trapped dirt and residues to be expelled, reducing fretting while maintaining structural integrity through the controlled rotational degree of freedom
Data Source
Figure 1A~2A
Figure 1~2
Figure 3~4
AI summary
The present invention refers to an assembly (2, 3) for a control and manoeuvre apparatus (1) of the blades (A, B) of a switch point and comprising: A coupling element (3) to the blade (A, B) comprising a surface (3') of connection to the blade and, on the opposite part, a seat (40); A tie rod (2) that is inserted in the seat (40) through one of its ends (2') presenting a slotting (10) that runs longitudinally in the direction of the length of the tie rod (2); The seat (40) being delimited superiorly by a superior surface (5') and inferiorly by an inferior surface (5''), both surfaces (5', 5'') further presenting a slotting (6', 6" ); A vertical pivot (4) passing through the slottings (6', 6'') of the superior (5') and the inferior surface (5") and the slotting (10) of the end (2') of the tie rod and that connects rotatably, around its axis, the tie rod (2) to the coupling element (3).