Torque Limiting Mechanism for Bicycle Load Carrier Wire Tensioning
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Solution Overview
Problem
Existing bicycle support assemblies with clamping jaws face issues due to high friction forces on wire mechanisms, leading to excessive wear and tear, and a need for a compact torque limiting mechanism to prevent accidents and reduce maintenance costs.
Innovation Solution
A tensioning device with a torque limiting mechanism using flexible elongated elements like wires or cords, where the torque transfer is limited to a predetermined threshold, utilizing gears and a resilient member to prevent excessive wear, and allowing the element to be wound or unwound about an axle for compactness, with a rotation lock to secure the bike.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the wire runs inside the support bar to remotely operate the clamping jaw, then the clamping jaw can be operated remotely, but the wire is subjected to high friction forces causing excessive wear and tear
Solution Approach 1:
A torque limiting mechanism is introduced as an intermediary between the wire and the clamping jaw. This mechanism includes a first torque transmission member (gear) connected to the wire and a second torque transmission member (gear) connected to the clamping jaw, with a resilient member (spring) between them that limits torque transfer. The mechanism allows remote operation while protecting the wire from excessive forces.
Solution Approach 2:
The resilient member (spring) in the torque limiting mechanism provides beforehand cushioning by absorbing excess torque before it can reach the wire. When the wire applies torque to the first gear, the spring compresses to limit the maximum torque transmitted to the second gear and clamping jaw, preventing wire damage from force spikes.
2Reliability
If a torque limiting mechanism is added to protect the wire, then wire wear is reduced, but the device complexity increases
Solution Approach 1:
The torque limiting mechanism changes the torque parameter transmitted through the system. The resilient member (spring) is pre-loaded to a specific force that corresponds to the maximum allowable torque on the wire. When torque exceeds this parameter threshold, the spring compresses to limit further torque transmission, automatically protecting the wire without complex control systems.
Solution Approach 2:
The torque limiting mechanism uses simple, inexpensive components (gears and a spring) that can be easily manufactured and replaced if needed. Rather than using a complex electronic control system with sensors and motors, the patent employs mechanical elements that are robust, simple, and cost-effective for limiting torque.
3Adaptability or versatility
If the wire is allowed to run along restricted paths with sharp edges and tight turns, then the load carrier design is more flexible, but the wear and tear on the wire increases negatively
Solution Approach 1:
The torque limiting mechanism with its resilient member provides beforehand cushioning against force spikes that occur when the wire contacts sharp edges or navigates tight turns. The spring absorbs these transient forces before they can damage the wire, allowing the wire to safely run along more flexible paths within the support bar.
Solution Approach 2:
The torque limiting mechanism acts as an intermediary that decouples the wire from direct mechanical stress. By placing the torque limiting mechanism between the wire and the clamping jaw, the wire is protected from the harmful effects of sharp edges and tight turns, as the mechanism limits the maximum force the wire can experience regardless of path restrictions.
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 solution reduces wear and tear on the elongated elements, allows them to navigate restricted paths without damage, and provides a secure, predictable torque transmission, reducing the risk of bike detachment during transport and minimizing maintenance costs.
Implementation Method 1
The first torque transmission member is biased towards the second torque transmission member using a resilient member such as a rubber member, a member having rubber like properties, or a spring
Implementation Method 2
The wire of such wire mechanism generally tends to run inside of a support bar. It has been found that there is a severe risk that the wire is subjected to unnecessary high friction forces
Data Source
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AI summary
The present disclosure relates to a tensioning device (10) for a load carrier, such as a bike carrier or a roof box. The tensioning device (10) comprises a torque limiting mechanism (20) which is adapted to limit the amount of transferable torque. The torque limiting mechanism (20) comprises a first and a second torque transmission member (21, 22). The first torque transmission member (21) is biased into working cooperation with the second torque transmission member (22) wherein upon a torque threshold value, the first and second torque transmission members (21, 22) are disengaged from the working cooperation so that a torque limiting function is provided. An activation member (14) is associated with the first torque transmission member (21) which enables a user to operate the first torque transmission member (21) to transfer torque to the second torque transmission member. The second torque transmission member (22) is associated with an elongated element (31, 32), such as a wire, which upon rotation of the second torque transmission member (22) is tensioned. The tensioning device enables a load retaining mechanism. Such as a clamping jaw (3), to be controlled remotely, while using the advantages of a torque limiting mechanism.