Parallel Four-Bar Locking Mechanism for Preset Display Position
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Solution Overview
Problem
The parallel four-bar mechanism used in medical and diagnostic equipment lacks a locking mechanism between the second and third bars, leading to difficulties in maintaining the display in a predetermined position during handling and transportation.
Innovation Solution
A stopping pin and slot mechanism is introduced, where a movable stopping pin on the second bar engages with a stopping slot on the third bar, driven by an actuating member, allowing for locking and unlocking positions to secure or release the mechanism, enabling the second and third bars to be locked in a preset angular position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If no locking means is provided between the second and third bars, then the structure remains simple and easy to manufacture, but translational movement may happen between the second and third bars, making it difficult to keep the display in a predetermined position
Solution Approach 1:
The locking mechanism is segmented into distinct components: a stopping block mounted on the second bar, a stopping slot formed in the stopping block, and a movable stopping pin mounted on the third bar. This segmentation allows each component to perform its specific function while maintaining overall structural simplicity.
Solution Approach 2:
The locking function is extracted as a separate, movable stopping pin that can be engaged or disengaged from the stopping slot as needed. This allows the mechanism to have locking capability without requiring a permanently complex structure, enabling the pin to be taken out of the engaged position when locking is not required.
2Reliability
If a locking mechanism is added to prevent translational movement between the second and third bars, then position stability is improved, but the device complexity increases
Solution Approach 1:
The locking mechanism is implemented locally at the interface between the second and third bars, with the stopping block and slot positioned only where needed to prevent translational movement. The rest of the four-bar mechanism maintains its original simple structure, minimizing the impact on manufacturing complexity.
Solution Approach 2:
The stopping pin acts as an intermediary element between the second and third bars, providing the locking function without requiring permanent modification to either bar. The pin can be easily manufactured and installed, serving as a simple mediator that enables or disables locking as needed.
3Ease of operation
If the stopping pin is made movable between locking and unlocking positions, then ease of operation is improved, but the device complexity increases
Solution Approach 1:
The stopping pin is designed to be movable rather than fixed, allowing it to dynamically transition between engaged and disengaged positions. This dynamic capability enables easy switching between locked and unlocked states, with the pin's movement guided by the stopping slot's geometry and actuated by simple forces.
Solution Approach 2:
The stopping pin can be actuated to move between locking and unlocking positions through simple applied forces, and the stopping slot's geometry provides guiding walls that automatically guide the pin's movement. The mechanism largely self-regulates the pin's position based on the forces applied and the slot's physical constraints.
Data Source
AI summary
A parallel four-bar mechanism is disclosed, having the second and third bars being parallel to each other and having their opposite ends hinged to the first and fourth bars respectively. A stopping block is provided with a stopping slot, and a movable stopping pin is configured to be engageable with the stopping slot. When an actuating member drives the stopping pin to disengage from the stopping slot, the second and third bars are able to translation relative to each other; and when the actuating member drives the stopping pin into the stopping slot, the second and third bars are locked with each other, with the second and third bars being not able to translation relative to each other, and thus the whole parallel four-bar mechanism is locked in a preset angular position.