Strap Tensioner With Visual Indicator and Torque-Limiting Clutch
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Solution Overview
Problem
Existing strap tensioning systems lack a reliable and persistent indication of tension levels, particularly in applications requiring precise adjustment and secure fastening, such as occupant harnesses, goods harnesses, and safety nets, which can lead to inadequate security or discomfort.
Innovation Solution
A strap tensioning assembly incorporating a torque limiting clutch and an in-line tension indicator that provides a persistent visual indication of tension, allowing for precise adjustment and secure fastening through a combination of ratchet mechanisms and resilient elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a strap tensioning system uses a ratchet mechanism for secure fastening, then the reliability of tension maintenance is improved, but the ability to provide precise tension indication deteriorates
Solution Approach 1:
A dial indicator mechanism is introduced as an intermediary between the ratchet mechanism and the external environment. The dial consists of a dial body with scale markings and a pointer that rotates in response to strap tension changes, providing precise visual indication without interfering with the ratchet's tension maintenance function.
Solution Approach 2:
The patent replaces direct mechanical observation of tension (checking strap tightness visually or manually) with a mechanical indication system. The dial indicator converts mechanical tension forces into readable angular displacements of the pointer, providing precise measurement while maintaining the simplicity of mechanical operation.
2Manufacturing precision
If a strap tensioning system provides precise tension adjustment, then the manufacturing precision of tension control is improved, but the device complexity increases
Solution Approach 1:
The dial indicator mechanism serves multiple functions simultaneously: it provides tension indication, tension measurement, and serves as part of the release mechanism. The same dial body and pointer assembly that indicates tension also moves to trigger release when the strap is loosened, reducing the need for separate components.
Solution Approach 2:
The patent combines the tension indication function with the release mechanism into a single integrated assembly. The dial body houses both the indication scale and the release trigger, eliminating the need for separate indication and release components, thereby reducing overall device complexity.
3Ease of operation
If a strap tensioning system uses a release mechanism for quick unfastening, then the ease of operation is improved, but the reliability of secure fastening may deteriorate
Solution Approach 1:
The release mechanism utilizes dynamic movement of the dial body relative to the housing. When the strap is loosened, the dial body moves axially to disengage the ratchet teeth, providing a clear mechanical transition between locked and unlocked states. This dynamic design ensures that the release action is both quick and unambiguous.
Solution Approach 2:
The dial indicator provides continuous visual feedback about the tension state of the strap. The pointer position clearly indicates whether the strap is tensioned or loosened, giving the operator feedback that confirms the release mechanism has properly disengaged, thereby maintaining reliability during quick unfastening operations.
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 system ensures consistent and visible tension indication, enabling secure fastening and preventing over-tightening or under-tightening, thereby enhancing safety and comfort in applications like occupant harnesses and goods harnesses.
Implementation Method 1
a resilient element disposed between the carriage and the housing to bias the carriage in a direction opposite to the tension direction along the tension axis
Implementation Method 2
the torque limiting clutch comprises a deformable friction member between a hub or drum, driven by the dial, and the reel
Data Source
AI summary
A strap tensioning assembly having a casing and a reel or a pair of reels. A dial rotates the reels to reel in a tension member on each reel. A first torque limiting clutch is provided between the first reel and the dial, such that a tension in the first tension member is limited.