Eccentric Braking Arm Friction Brake for Fishing Reel Backlash Control
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Solution Overview
Problem
Existing rotational friction brakes, such as centrifugal and magnetic brakes, are not effectively regulated by angular acceleration, leading to inefficient braking in applications like fishing reels, where high angular speeds require precise control during both positive and negative acceleration phases, resulting in reduced cast length and user experience issues.
Innovation Solution
A rotational friction brake design where the pivot point and mass center of the braking arm are eccentrically offset, allowing the arm to remain inactive during positive acceleration and actively engage during negative acceleration, with adjustable stop members to control the braking action, enabling smooth transitions and tailored braking power based on angular acceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rotational friction brake is used to prevent line rise during negative angular acceleration, then line entanglement is prevented, but the brake must be immediately actuated during positive angular acceleration which reduces cast length
Solution Approach 1:
The brake system dynamically transitions from static to kinetic friction based on rotational direction. During positive angular acceleration (casting), the brake operates in static friction mode allowing free rotation. During negative angular acceleration (retrieval), it transitions to kinetic friction mode providing braking action. This dynamic behavior prevents line entanglement while maintaining cast length.
Solution Approach 2:
The brake mechanism changes the friction parameter from static to kinetic based on operational phase. Static friction (higher coefficient) engages during retrieval to provide strong braking, while kinetic friction (lower coefficient) operates during casting to minimize resistance. This parameter change resolves the contradiction between reliable entanglement prevention and maintained productivity.
2Reliability
If centrifugal brakes are used to limit rotational speeds, then line rise is controlled, but high angular speeds required for long casts are limited
Solution Approach 1:
The brake applies periodic action rather than continuous centrifugal force. During the casting phase (positive acceleration), the brake remains disengaged allowing high angular speeds. During the retrieval phase (negative acceleration), the brake engages to control line rise. This periodic engagement pattern maintains both high speed capability and line rise control.
Solution Approach 2:
The system transitions from static brake design to dynamic brake engagement. The brake is activated only during negative angular acceleration phases when line rise occurs, rather than continuously as in centrifugal brakes. This dynamic activation allows high angular speeds during casting while providing line rise control during retrieval.
3Speed
If braking action occurs during positive angular acceleration, then rotational speed is controlled, but the phase where line is pulled off spool is interrupted reducing efficiency
Solution Approach 1:
The braking action is segmented into distinct operational phases. The brake is activated only during negative angular acceleration (retrieval phase) and remains inactive during positive angular acceleration (casting phase). This segmentation allows uninterrupted line payout during casting while providing necessary speed control during retrieval.
Solution Approach 2:
The brake operates periodically based on rotational direction changes. During positive acceleration cycles, the brake is disengaged to maximize line payout efficiency. During negative acceleration cycles, the brake engages to control rotational speed. This periodic operation pattern eliminates unnecessary braking during productive casting phases.
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
This design provides controlled braking power during both positive and negative angular accelerations, preventing backlash and enhancing cast length and user experience in fishing reels and other applications by ensuring smooth engagement and disengagement of the braking mechanism.
Implementation Method 1
The rotational friction brake is actuated by a positive or negative angular acceleration of the second body
Data Source
Figure 1~2
Figure 3a~6
Figure 7~8
AI summary
Disclosed is a rotational friction brake (1) regulated by the rate of change of the angular speed, comprising: a first body (10), a second body (12) rotationally attached to said first body, said second body being arranged to rotate around a rotational center axis (14) of said second body, at least one braking arm (16) rotationally attached to said second body in a pivot point (18), wherein said pivot point is eccentrically offset to said rotational center axis, said at least one braking arm comprises a braking member (21a, 21b) arranged to frictionally engage a part of said first body, said at least one braking arm having a mass center (22) placed at a distance from said pivot point (18) that is longer than a distance from said pivot point to said rotational center axis (14), wherein said braking member is arranged to frictionally engage said part of said first body. The disclosure further relates to a fishing reel (50) comprising such a rotational friction brake.