Swivel Caster Assembly With Bracket Pivot for Straight-Line Stability
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Solution Overview
Problem
The existing swivel castor arrangements for furniture, particularly beds, face challenges in maintaining straight-line stability during long-distance movement due to unrestricted rotation around the second axis of rotation, which is advantageous for maneuverability but detrimental for straight-line travel, and the folding mechanism for releasing this rotation is limited by space constraints.
Innovation Solution
The swivel castor arrangement allows the bracket to pivot by less than 90° and incorporates holding elements to maintain the bracket in a position that restricts rotation, using a ball catch mechanism and an arcuate elongated hole to secure the bracket, enabling the wheel to be freely rotated or blocked between the legs, with a pedal for easy operation, and an optional second swivel castor with identical construction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the bracket is folded over to release rotation of the swivel caster, then maneuverability is improved, but the space required for folding is not available for other configurations
Solution Approach 1:
The bracket's movement is segmented into two independent functions: a small pivot angle (less than 90°) for releasing rotation restriction, and a separate folding mechanism for compact storage. This segmentation allows the bracket to perform rotation release without requiring large folding space, as the pivot action occurs within the available angular range while folding is handled by a different mechanical arrangement.
Solution Approach 2:
The solution transitions from a single-dimensional folding motion (requiring large space) to a multi-dimensional approach combining a small pivot angle in one dimension with a folding mechanism in another dimension. The bracket pivots upward by less than 90° to release rotation, while the folding capability is achieved through a separate hinge arrangement that moves the bracket in a different spatial plane, thereby resolving the space conflict.
2Volume of moving object
If the bracket pivots by less than 90° to release rotation, then the space requirement is reduced, but the bracket must still clear the wheel to allow free rotation
Solution Approach 1:
The legs of the bracket incorporate an upward curve between the connection points and the third rotation axis. This curved geometry allows the bracket to pivot upward by less than 90° while maintaining sufficient clearance above the wheel. The curvature of the legs provides the necessary spatial clearance without requiring a full 90° pivot, thereby reducing the space requirement while still enabling free wheel rotation.
3Stability of the object's composition
If holding elements are added to secure the bracket, then straight-line stability is improved, but the device complexity increases
Solution Approach 1:
The holding elements are designed to automatically engage and disengage based on the bracket's position. When the bracket is in the restricted position, the holding elements automatically secure it to maintain straight-line stability. When the bracket pivots to release rotation, the holding elements automatically disengage without requiring additional actuators or complex control mechanisms. This self-service approach provides stability enhancement while minimizing the increase in device complexity.
Data Source
Figure 1
Figure 2
Figure 2a
AI summary
The invention relates to a caster assembly (L) for a piece of furniture, in particular for a bed, comprising: - a holder (2), - a first caster (3), - the first caster (3) comprising a wheel (32) and a frame (31), - the wheel (32) being rotatably mounted on the frame (31) about a first axis of rotation which lies in a first plane, and - the frame (31) being rotatably mounted at least indirectly on the holder (2) about a second axis of rotation which lies perpendicular to the first plane, - a U-shaped bracket (5) comprising two legs (52) and a web connecting the legs (51), - the legs (52) being pivotably mounted at least indirectly on the holder (2) about a third axis of rotation which lies in the first plane or in a plane parallel to the first plane, - the bracket (5) being pivotable about the third axis of rotation between a first position and a second position, - the bracket (5) then being moved into the second position is movablewhere the first axis of rotation and the third axis of rotation are substantially parallel or coincide, - wherein the wheel (32) in the second position is arranged between the two legs (52) of the bracket (5) so that free rotation of the frame (31) about the second axis of rotation is restricted, - wherein the wheel (32) in the first position is not arranged between the two legs (52) of the bracket (5) so that free rotation of the frame (31) about the second axis of rotation is possible, - wherein the bracket (5) is pivotable by less than 90° to change from the first position to the second position and vice versa, and - wherein the caster assembly (L) further comprises retaining elements (53, 9) that can hold the bracket (5) in the first position.