Self-Locking Foldable Chassis for Hand Trucks
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Solution Overview
Problem
Manually driven carrier vehicles, such as hand trucks and carts, face challenges with foldable chassis that require additional mechanisms to prevent inadvertent folding, adding complexity and expense, and lack a simple way to lock the chassis in an unfolded position for stability and ease of use.
Innovation Solution
A foldable chassis with independently lockable platform and wheel mechanisms, featuring a single degree of freedom plain linkage and a three-dimensional linkage, allowing for easy locking in both unfolded and folded states, and a lever to secure the actuator positions, enabling the chassis to fold flat for improved portability and handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional means are added to prevent inadvertent folding, then reliability is improved, but device complexity increases
Solution Approach 1:
The chassis mechanisms are designed to automatically lock in the unfolded position through self-locking features inherent in the linkage geometry, eliminating the need for additional active locking components. The system serves itself by using the mechanical arrangement to maintain stability without requiring extra means.
Solution Approach 2:
The patent employs dynamic locking where the chassis transitions from a locked unfolded state to a locked folded state through controlled movement. The locking mechanism is integrated into the motion path, allowing the system to lock automatically during the folding/unfolding transition without requiring separate locking actions or components.
2Stability of the object's composition
If additional means are added to lock the chassis, then stability is improved, but ease of operation deteriorates
Solution Approach 1:
The chassis automatically locks in the unfolded position through its own structural design, without requiring the user to perform additional locking actions. The self-locking feature is inherent in the linkage mechanism, making the system stable while remaining simple to operate.
Solution Approach 2:
The locking action is built into the unfolding motion itself - as the chassis unfolds, the geometry of the linkage automatically engages the locked position. This preliminary integration of locking into the basic motion eliminates the need for separate locking steps, maintaining ease of operation.
3Ease of operation
If the chassis is designed to fold flat, then portability is improved, but device complexity increases
Solution Approach 1:
The chassis is divided into separable components - the platform and wheel assemblies are connected to the frame through independent folding linkages. This segmentation allows each component to fold independently, enabling the chassis to collapse into a compact flat configuration while using simple, separate folding mechanisms rather than a complex integrated system.
Solution Approach 2:
The folding mechanism uses dynamic linkages that allow smooth transitions between unfolded and folded states. The single-degree-of-freedom plain linkage and three-dimensional linkage enable controlled folding motion, achieving a flat collapsed configuration through inherent geometric constraints rather than complex mechanical guides.
Data Source
AI summary
Disclosed is a foldable chassis of manually driven carrier vehicles capable of self-locking in unfolded position. The chassis includes a frame having a reference plane, an actuator attached pivotally to said frame, a first mechanism comprising said actuator and a platform attached pivotally to said frame, and a second mechanism comprising said actuator and two arms, each attached to said frame pivotally around a first axis and configured for attaching a wheel arrangement rotatable around a second axis. Said first and second mechanisms configured to move independently of each other between at least a first position, in which said platform generally perpendicular to said frame and said wheel arrangements generally perpendicular to said reference plane, and a second position, in which said platform adjacent to said frame and said wheel arrangements adjacent and parallel to said reference plane.