Four-bar linkage door mechanism for tight space
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Solution Overview
Problem
Conventional hinged doors require significant clearance and space to open and close, making them unsuitable for tight spaces, and existing solutions like sliding doors still face limitations in minimal space requirements.
Innovation Solution
A storage container with a four-bar linkage system that includes a cam and worm drive mechanism, allowing doors to open and close with minimal space requirements by using a mechanical advantage to compress weather seals and lock the doors against the frame.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional hinged doors are used, then the door can be simply constructed and manufactured, but the door requires substantial clearance and space to open and close
Solution Approach 1:
The door system is segmented into multiple components: a four-bar linkage mechanism with separate links (input link, output link, coupler link), a cam mechanism with follower, and a latch assembly. This segmentation allows the door to move through a compact path rather than requiring a large arc, reducing the clearance space needed while maintaining manufacturability of individual components.
Solution Approach 2:
The door movement is transformed from a simple rotational arc about a hinge axis to a more complex multi-dimensional path controlled by the four-bar linkage and cam mechanism. The follower rides along the cam profile, converting rotational cam motion into the desired door movement path, effectively utilizing multiple degrees of freedom to achieve compact operation.
2Area of stationary object
If sliding doors are used to reduce space requirements, then the front space is reduced, but side space requirements still exist and the mechanism becomes more complex
Solution Approach 1:
The invention merges multiple functions into a single integrated mechanism: the four-bar linkage provides both the motion path control and the mechanical advantage for force multiplication, while the cam mechanism simultaneously controls the door position and engages the latch. This consolidation achieves compact space requirements without proportionally increasing overall system complexity.
Solution Approach 2:
The cam profile is specifically designed with a pressure angle no greater than 15° to optimize the mechanical advantage and force transmission. The geometric parameters of the four-bar linkage are carefully selected to achieve the desired motion path while minimizing the required space. These parameter optimizations allow the mechanism to be compact yet mechanically efficient.
3Area of stationary object
If a cam and worm drive mechanism is used to achieve minimal space requirements, then the space efficiency is improved, but the device complexity increases
Solution Approach 1:
The worm drive mechanism provides self-locking capability, automatically maintaining the door in the closed and latched position without requiring continuous power or active control. The mechanical advantage of the worm gear (greater than 400:1) creates sufficient friction to hold the door against external forces, making the system self-sustaining once latched and reducing the need for complex control systems.
Solution Approach 2:
The invention replaces electronic or hydraulic door closing and latching systems with a purely mechanical cam and worm drive mechanism. This substitution achieves the desired compact space requirements while using reliable mechanical components that are simpler to control and maintain than their electronic or hydraulic counterparts.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables efficient door movement and closure in tight spaces with minimal front and side space, providing a visually appealing and space-efficient solution for autonomous delivery vehicles and other applications.
Implementation Method 1
A mechanical advantage between the motor assembly and the follower may lock the closure member against the frame
Implementation Method 2
The latch assembly may comprise a cam pivotally coupled within the latch assembly
Implementation Method 3
Pivotal displacement of the cam in a first direction may pull the follower toward the frame compressing the weather seal
Data Source
AI summary
An example retention assembly has a motor assembly and a self-locking worm drive coupled thereto. A cam is fixed to a worm gear of the worm drive. The retention assembly has an actuation shaft including a follower. The actuation shaft is displaceable over a displacement range via rotation of the cam. The retention assembly has a securement member with a securement member follower, the securement member coupled to a portion of the actuator shaft. The retention assembly has a housing cam included as part of the retention assembly housing and against which the securement member follower is biased. The securement member are in an open state when the actuation shaft is in a first position. The securement member swings outward to a retaining position as the actuation shaft is moved to a second position.