Spool Brake Analog Current Control for Dual-Bearing Reel Stability
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Solution Overview
Problem
Existing spool brake devices for dual-bearing reels experience instability in braking force due to variations in electromotive force of the coil, caused by differences in size and attachment position of the magnet and coil, leading to inconsistent braking performance.
Innovation Solution
A spool brake device with a magnet that rotates in conjunction with the spool, a coil to generate electric current, a tension detecting unit, and a spool control unit that analog-controls the electric current flowing through the coil based on tension measurements, ensuring stable braking force application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If digital switching control is used to regulate braking force, then the control mechanism is simple and easy to implement, but the braking force becomes unstable when electromotive force of the coil varies
Solution Approach 1:
The patent implements feedback control by detecting the actual current flowing through the coil and comparing it with the target current value. The spool control unit then adjusts the duty cycle of the switching element based on this feedback to maintain the target braking force. This closed-loop feedback mechanism compensates for variations in electromotive force caused by magnet size and position differences, thereby stabilizing the braking force while maintaining relatively simple control logic.
Solution Approach 2:
The patent dynamically changes the duty cycle parameter of the switching element based on detected current values and target braking force requirements. By adjusting this control parameter in real-time, the system compensates for variations in electromotive force and maintains stable braking performance. The control unit modifies the duty cycle proportionally to the difference between target and actual current, enabling adaptive regulation without complex mechanical adjustments.
2Ease of manufacture
If the magnet and coil sizes and positions vary during manufacturing, then manufacturing precision requirements are reduced and ease of manufacture improves, but the electromotive force varies causing unstable braking force
Solution Approach 1:
The patent enables the spool brake device to self-correct for manufacturing variations through its feedback control mechanism. The system automatically detects variations in electromotive force caused by magnet and coil position/size differences and compensates for them by adjusting the duty cycle accordingly. This self-service capability allows the system to maintain stable braking force without requiring high-precision manufacturing, as the control system adapts to the actual physical characteristics of each assembled unit.
Solution Approach 2:
The current detection unit continuously monitors the actual current generated by the magnet-coil interaction, and the spool control unit uses this feedback information to adjust the duty cycle. This feedback loop automatically compensates for manufacturing variations in magnet and coil dimensions and positions, allowing the system to achieve consistent braking force despite tolerances in manufacturing. The feedback mechanism transforms physical variations into controllable electrical parameter adjustments.
3Speed
If duty cycle is used as the control parameter for braking force, then the control is simple and responsive, but the braking force becomes inconsistent when electromotive force varies
Solution Approach 1:
The patent uses feedback control where the actual current is detected and compared with the target current corresponding to the desired braking force. The spool control unit adjusts the duty cycle based on this feedback to maintain accurate braking force. This feedback mechanism preserves the fast response characteristics of duty cycle control while adding the accuracy needed to compensate for electromotive force variations, achieving both speed and reliability in the control system.
Solution Approach 2:
The system dynamically changes the duty cycle parameter based on real-time current detection and target braking force requirements. By proportionally adjusting the duty cycle according to the difference between target and actual current, the system maintains both rapid response (inherent in duty cycle control) and accurate braking force (achieved through parameter adjustment). This dynamic parameter change approach allows the system to respond quickly while compensating for electromotive force variations.
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 provides stable and consistent braking force to the spool, regardless of variations in electromotive force, by accurately controlling the electric current through analog control, thereby maintaining reliable braking performance.
Implementation Method 1
a coil configured opposite to the magnet to generate electric current with rotation of the magnet
Data Source
AI summary
A spool brake device for a dual-bearing reel according to a first aspect of the present invention is a device configured to electrically brake a spool rotatably mounted to a reel unit of the dual-bearing reel for allowing a fishing line to be wound thereabout. The spool brake device includes a spool brake unit including a magnet configured to rotate in conjunction with rotation of the spool, and a coil configured opposite to the magnet to generate electric current with rotation of the magnet, a tension detecting unit configured to detect and measure tension on the fishing line, and a spool control unit configured to control the spool brake unit by analog-controlling electric current flowing through the coil on the basis of how large the tension is.