Cam-Strap Device Distributing Clamping Force to Reduce Localized Stress
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Solution Overview
Problem
Existing devices for securing flat straps, such as ratchet and cam-lock devices, face limitations including high complexity, localized stress issues, and potential for inadvertent release, which restrict their load-bearing capacity and usability.
Innovation Solution
A cam-strap device with a rotating hub and gripping surface that provides adjustable tension and secure attachment options, allowing for higher mechanical advantage and reduced localized stress, while preventing inadvertent release through a design that distributes clamping force over a larger area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a ratchet device is used to achieve high tension in flat straps, then the load-bearing capacity is improved, but the device complexity increases significantly
Solution Approach 1:
The patent combines the cam mechanism and ratchet mechanism into a single integrated device body, merging two separate functions (tensioning and locking) into one unified structure. This eliminates the need for separate ratchet devices while maintaining high load-bearing capacity through the synergistic interaction of cam clamping force and ratchet mechanical advantage.
Solution Approach 2:
The device body serves multiple functions simultaneously: it provides the cam mechanism for initial tensioning, the ratchet mechanism for mechanical advantage and locking, and the drum for strap winding. This multi-functionality reduces overall system complexity by consolidating what would traditionally require multiple separate components.
2Ease of operation
If a cam-lock device is used for ease of operation, then the ease of operation is improved, but the load-bearing capacity is limited
Solution Approach 1:
The patent merges the cam mechanism (providing ease of operation through simple lever action) with the ratchet mechanism (providing high mechanical advantage for load-bearing). The cam provides initial clamping force that is easy to apply, while the ratchet amplifies this force to achieve high load-bearing capacity, combining the advantages of both device types.
3Power
If the flat strap is drawn into the device to increase tension, then the mechanical advantage is improved, but the flat strap may misalign or foul rendering the device unusable
Solution Approach 1:
The patent applies local quality by creating a gradually widening cam gap that guides the flat strap through its entire path of insertion. The cam surface geometry is specifically designed to maintain proper alignment at each stage of strap insertion, preventing misalignment and fouling while still achieving the necessary mechanical advantage through the cam's leverage action.
4Strength
If the cam force is increased to accommodate higher tension, then the load-bearing capacity is improved, but the localized stress on the flat strap increases
Solution Approach 1:
The patent transitions from a single-point contact cam mechanism to a distributed area contact mechanism. The cam gap widens progressively along the strap's path, distributing the clamping force across multiple points and a larger area of the flat strap. This dimensional change from point to area contact reduces localized stress while maintaining the necessary cam force for high load-bearing capacity.
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 cam-strap device offers a higher mechanical advantage comparable to ratchet devices with the simplicity of cam-lock devices, effectively utilizing a larger percentage of the flat strap's load capacity and minimizing the risk of accidental release, thus enhancing both usability and load-bearing capabilities.
Implementation Method 1
a cam area for adjustably attaching a strap... a hub oriented in the cam area such that the hub may rotate to capture the strap between the hub and the device body
Implementation Method 2
capture the strap between the hub and the device body
Implementation Method 3
The spring is positioned within the device body and biases the hub toward the gripping area
Implementation Method 4
A cam-strap device with a rotating hub and gripping surface that provides adjustable tension and secure attachment options, allowing for higher mechanical advantage
Data Source
AI summary
A flat strap holding apparatus includes a body and a rotating hub that rotates in an interior of the body. A gripping surface of the rotating hub is proximate to a gripping area in the interior of the body. The rotating hub is configured to rotate towards and away from the gripping area. The body has an attachment area, the attachment area having a plurality of apertures and a plurality of bars. The attachment area is located on a first side of the body and the rotating hub, and the interior is located on a second side of the body.