Footrest extension device, frame and chair having the same
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Solution Overview
Problem
Existing footrest extension devices for chairs suffer from poor stability due to complex structures and mismatched joints, leading to inaccurate motion trajectories and excessive wear, which results in failure over time.
Innovation Solution
The implementation of a footrest extension device comprising multiple connecting rods forming five interconnected four-bar mechanisms, driven by a rocker arm and transmission system, ensuring precise and consistent motion trajectories and reducing wear by preventing excessive folding and collision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a complex structure with many elements is used in the footrest extension device, then the footrest can be extended and retracted, but the stability during operation deteriorates and joints experience excessive wear
Solution Approach 1:
The footrest extension device is divided into multiple connecting rods (first through eighth connecting rods) that form separate four-bar mechanisms. Each mechanism segment handles a specific portion of the motion trajectory, allowing the complex extension and retraction function to be broken down into manageable, stable segments that reduce overall system complexity and improve reliability.
Solution Approach 2:
The patent introduces intermediate connecting rods (third, fourth, fifth, sixth, seventh connecting rods) that act as mediators between the driving device and the footrest platform. These intermediate elements transmit motion through precisely designed four-bar mechanisms, ensuring smooth transitions and reducing direct stress on joints, thereby improving operational stability and reducing wear.
2Reliability
If the structure is simplified to improve stability, then wear is reduced, but the motion trajectory accuracy deteriorates
Solution Approach 1:
The patent employs dynamic four-bar mechanisms where the connecting rods are arranged to naturally guide the footrest platform along a predetermined motion trajectory. The dynamic configuration of these mechanisms ensures that as the footrest extends and retracts, it follows an accurate path while maintaining structural stability, resolving the contradiction between simplicity and precision.
3Ease of manufacture
If traditional joint connections are used, then the device is easier to manufacture, but the joints experience excessive wear and failure over time
Solution Approach 1:
The patent optimizes the geometric parameters of the four-bar mechanisms, including the lengths and angles of connecting rods, to achieve precise motion trajectories. By carefully selecting and adjusting these parameters during the design phase, the joints operate under optimized conditions that minimize wear while maintaining ease of manufacture through standard connecting rod configurations.
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
The solution enhances stability and response sensitivity, maintaining consistent motion trajectories and reducing wear, thereby improving the overall performance and longevity of the footrest extension device.
Implementation Method 1
The first connecting rod is connected to a main frame, and pivotally connected to the second connecting rod and the third connecting rod, respectively. The second connecting rod is connected to the main frame, and pivotally connected to the fourth connecting rod.
Data Source
AI summary
A footrest extension device for a chair includes eight connecting rods: a first connecting rod is connected to a main frame, and pivotally connected to a second connecting rod and a third connecting rod, respectively; the second connecting rod is connected to the main frame, and pivotally connected to a fourth connecting rod; the third connecting rod is pivotally connected to the fourth connecting rod, a sixth connecting rod and a eighth connecting rod, respectively; a fifth connecting rod is pivotally connected to the fourth connecting rod and the sixth connecting rod, respectively; the sixth connecting rod is pivotally connected to a seventh connecting rod; the seventh connecting rod is pivotally connected to the eighth connecting rod; and the second connecting rod, driven by a driving device, drives the other connecting rods to move, so the footrest extension device is folded or extended.