Retractable Leash Spool Braking Using Tension Deflection
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Solution Overview
Problem
Existing retractable leash devices rely solely on handler strength for braking, leading to inconsistent and potentially harmful jerking when the animal runs away, and lack a structurally simple and cost-effective solution for automatic braking.
Innovation Solution
A retractable leash device with a braking element that automatically brakes due to leash tension, featuring a brake deflection device that transmits leash tension to the braking element, and an optional manual brake switch for adjustable braking force, allowing automatic or manual control of the spool's rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a brake switch is used to mechanically engage the spool and block further rotation, then the animal can be stopped before the end of the unwound leash is reached, but the braking effect depends solely on the strength of the handler, leading to inconsistent braking and potential jerking
Solution Approach 1:
The braking device automatically engages the brake element with the spool body based on the unwinding state, without requiring manual operation. The system self-regulates the braking force through the mechanical interaction between the brake element and spool, eliminating dependency on handler strength and providing consistent braking action.
Solution Approach 2:
The brake deflection device monitors the unwinding state of the leash and automatically adjusts the braking force accordingly. When the leash approaches its fully unwound state, the feedback mechanism triggers the brake element to engage with the spool body, providing automatic feedback-based control that ensures consistent braking regardless of handler strength.
2Adaptability or versatility
If the spool is completely unwound to allow the animal maximum freedom, then the animal can move far from the handler, but the animal experiences an abrupt jerk when the leash end is reached
Solution Approach 1:
The braking device activates before the leash reaches its fully unwound state, applying a gradual braking force that prevents the abrupt jerk. The brake element engages with the spool body in advance, creating a deceleration effect that smoothly limits the animal's movement without sudden stops, thereby eliminating the harmful jerk while maintaining near-maximum freedom.
3Extent of automation
If a brake deflection device is added to transmit leash tension to the braking element, then automatic braking is achieved, but the device complexity increases
Solution Approach 1:
The brake deflection device is integrated with the existing spool and housing structure, combining multiple functions into a unified mechanical system. The deflection device merges the leash tension transmission path with the braking mechanism, allowing automatic braking to be achieved through the existing structural elements rather than adding completely separate components.
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 consistent, automatic braking before the leash end is reached, reducing the risk of jerking and allowing adjustable braking force based on leash tension, enhancing safety and usability.
Implementation Method 1
a return spring (5), wherein the return spring (5) is designed to push or restrain the spool body (4) into a winding position
Implementation Method 2
the braking element (8) automatically brakes the spool body (4) as a result of a braking force generated by the unwinding of the animal leash (2)
Data Source
Figure 1~3
Figure 4~6
Figure 7~9
AI summary
The invention relates to a retractable leash device (1) for winding and unwinding an animal leash (2) comprising a housing (3), a spool body (4) rotatably mounted on the housing (3), and a return spring (5) which is designed to push or restrain the spool body (4) into a winding position in which the animal leash (2) is wound onto the spool body (4). The spool body (4) is rotatable from the winding position against a return force of the return spring (5) for unwinding the wound animal leash (2), wherein a braking device (7) is provided with a braking element (8) designed to brake the rotating spool body (4), which is designed such that the braking element (8) automatically brakes the spool body (4) as a result of a braking force generated by the animal leash (2) being unwound.The braking device (7) has a brake deflection device (11) on which the animal leash (2) is guided in a deflected manner and which is movably mounted on the housing (3) relative to the spool body (4) and which is designed to transmit the animal leash tension to the braking element (8).