Four-Bar Load Balancing Arm Adjustment for Pivot Axis Parallelism

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Solution Overview

Problem

Existing load balancing arms in medical device support systems face challenges in maintaining parallel alignment of the axis about which a medical device load pivots and the axis about which the proximal end hub pivots due to manufacturing tolerances and stack-up variations, leading to non-optimal orientation of the medical device.

Innovation Solution

A parallelism adjustment mechanism is introduced in the load balancing arm, utilizing a four-bar linkage with a distal hub that can pivot between two positions, adjusting the angle of the axis D-D relative to axis P-P to ensure parallel alignment, using fasteners and serrated flange screws to secure the hubs and compensate for assembly deflection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a four-bar linkage construction is used in the load balancing arm, then the structural stability and load-bearing capability are improved, but the manufacturing precision and parallelism alignment between axes deteriorate due to tolerance stack-up

Engineering Contradiction:
Improvestructural stabilityVSAvoidparallelism alignment
Core Design Contradiction:
Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The invention introduces an adjustable mechanism that allows the distal hub to be repositioned relative to the distal end vertical block. This dynamic adjustment capability enables compensation for manufacturing tolerances and assembly variations, allowing the system to achieve proper parallelism alignment between the proximal hub axis and distal hub axis after assembly, thereby resolving the contradiction between structural stability and manufacturing precision.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention allows changing the angular parameter of the distal hub orientation through adjustable mounting. By providing multiple positions or adjustable mounting for the distal hub on the distal end vertical block, the system can adjust the orientation parameter to compensate for tolerance stack-up in the four-bar linkage components, maintaining parallelism alignment while preserving structural stability.

Inventive Principle:
Principle #35Parameter changes

2Device complexity

If fixed mounting of hubs is used, then the device complexity is reduced, but the adaptability to compensate for manufacturing tolerances deteriorates

Engineering Contradiction:
Improvemounting mechanism complexityVSAvoidtolerance compensation capability
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The invention introduces an adjustable mounting mechanism for the distal hub on the distal end vertical block, transforming a static fixed mounting into a dynamic adjustable one. This allows the mounting position or orientation to be adjusted to compensate for manufacturing tolerances, providing adaptability while maintaining reasonable device complexity through a straightforward adjustment mechanism.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP4236897B1Parallelism adjustment mechanism for load balancing arm
Publication Date: 2026.01.21 AMERICAN STERILIZER CO
  • EP4236897B1 patent drawingFigure 1A
  • EP4236897B1 patent drawingFigure 1B
  • EP4236897B1 patent drawingFigure 1C

AI summary

A load balancing arm (20) for a medical device support system includes a proximal hub (22, 120, 114), a support arm (50), a link (90), and a distal end vertical block (112). The components together form a four bar linkage. The proximal hub is configured for pivotable movement about an axis P-P. A distal hub (122) is configured to support a medical device load for pivotable movement about an axis D-D. The distal hub (122) is mounted to the distal end vertical block(112) for pivotable movement between a first position in which the axis D-D is at a first angle relative to the axis P-P and a second position in which the axis D-D is at a second angle relative to the axis P-P, wherein the first angle is different than the second angle. A parallelism adjustment mechanism enables the axis D-D to be adjusted so as to be substantially parallel to the axis P-P.