Parking Brake Toggle Mechanism with Rotatable Junctions
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Solution Overview
Problem
Conventional parking brake devices with toggle link mechanisms achieve a high lever ratio but result in a small output stroke, making it difficult to obtain both a high lever ratio and large stroke simultaneously.
Innovation Solution
A parking brake device with a toggle mechanism featuring two rotatable junction parts connected to the brake lever, where one junction part connected to the intermediate position of the lever becomes rotatable about a connecting portion when the operation angle exceeds a predetermined angle, allowing for a larger output stroke while maintaining a high lever ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a toggle link mechanism is used to achieve a high lever ratio, then the operation force is reduced, but the output stroke becomes small
Solution Approach 1:
The junction member is divided into two rotatable junction parts (first and second junction parts) that can rotate relative to each other. This segmentation allows the mechanism to achieve both high lever ratio and large stroke by enabling different rotation modes: integral rotation for high lever ratio and relative rotation for extended stroke.
Solution Approach 2:
The junction parts are designed to dynamically change their rotational behavior based on the operation angle. When the operation angle is small, they rotate integrally to maintain high lever ratio. When the operation angle exceeds a predetermined angle, they rotate relative to each other to extend the output stroke, thus adapting to different operational phases.
2Power
If a high lever ratio is achieved, then a small operation force is required, but a large output cannot be obtained due to small stroke
Solution Approach 1:
The mechanism dynamically adjusts its configuration through the rotatable junction parts. During the initial phase (small operation angle), the integral rotation maintains high lever ratio for force multiplication. During the later phase (large operation angle), the relative rotation extends the stroke to achieve large output displacement, thus achieving both high power and large stroke.
Solution Approach 2:
The mechanism changes its geometric parameters (rotation mode of junction parts) based on the operation angle. This parameter change allows the system to optimize the lever ratio and stroke relationship at different stages of operation, achieving both high force multiplication and large output displacement.
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 device achieves a larger output force with the same operation force by increasing the stroke without a sharp increase in lever ratio, resulting in a greater braking force at maximum operation angle compared to conventional designs.
Implementation Method 1
the toggle link mechanism includes technical features; (1) capability of achieving a high lever ratio
Implementation Method 2
The junction member includes two junction parts that are connected to each other and are rotatable relative to each other
Data Source
AI summary
A parking brake device includes a toggle mechanism including a base member, a connecting member, a brake lever, a junction member that connects an intermediate position of the brake lever with the connecting member. The junction member includes two junction parts that are connected to each other and are rotatable relative to each other. During a process of an operation of the braking lever from a non-operating state of the parking brake device to an operating state of the parking brake device, the two junction parts integrally rotate when an operation angle of the brake lever is equal to or less than a predetermined angle, and one of the two junction parts connected to the intermediate position of the brake lever is rotatable about a connecting portion where the two junction parts are connected.