Two-Pawl Cargo Restraint With Automatic Erect-Position Locking
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Solution Overview
Problem
Existing cargo restraints for aircraft lack a reliable mechanism to automatically lock two pawls in an erect position, which can lead to unintended retraction during cargo handling operations.
Innovation Solution
A two-pawl cargo restraint system with a locking pawl that is automatically positioned in the locked position by a spring when the inner and outer pawls are rotated to the erected position, ensuring secure engagement and preventing accidental retraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a two-pawl cargo restraint system is used without an automatic locking mechanism, then the device complexity is reduced, but the reliability of maintaining the erected position deteriorates due to potential unintended retraction
Solution Approach 1:
The locking pawl is designed to automatically engage with the inner or outer pawl when they are in the erected position, without requiring manual intervention. The spring automatically pushes the locking pawl into the engaged position, creating a self-locking mechanism that maintains the erected position reliably without adding complex control systems.
Solution Approach 2:
The locking pawl acts as an intermediary element between the inner and outer pawls. It provides a mechanical linkage that physically connects the two pawls when in the erected position, preventing unintended retraction while maintaining a relatively simple overall structure.
2Ease of operation
If a spring-loaded automatic locking mechanism is added to the two-pawl system, then the ease of operation is improved through automatic locking, but the device complexity increases
Solution Approach 1:
The spring-loaded locking pawl automatically engages when the inner and outer pawls are positioned in the erected state, eliminating the need for manual locking operations. The system serves itself by using the positional information of the pawls to trigger the locking action automatically.
Solution Approach 2:
The spring is pre-loaded to exert force on the locking pawl, preparing it for automatic engagement before the pawls reach the erected position. This preliminary action ensures that as soon as the pawls are in the correct position, the locking mechanism is already primed to engage immediately.
3Reliability
If the locking pawl is rotatably coupled to the outer pawl with spring activation, then the reliability of the locking mechanism is improved, but the manufacturing precision requirements worsen due to the need for precise rotational coupling and spring calibration
Solution Approach 1:
The locking pawl is designed with rotational freedom rather than rigid fixation, allowing it to dynamically adjust to slight variations in manufacturing tolerances. The spring provides a flexible force that can accommodate small dimensional variations while maintaining reliable locking engagement.
Solution Approach 2:
The spring force parameter is designed to be sufficient to overcome normal manufacturing variations and maintain reliable engagement. By adjusting the spring characteristics (force constant, preload), the system can compensate for tolerances in the rotational coupling without requiring extremely tight manufacturing precision.
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 provides a secure and automatic locking mechanism that maintains the pawls in the erect position, enhancing cargo safety during aircraft operations by reducing the likelihood of accidental retraction and ensuring consistent restraint performance.
Implementation Method 1
The cargo restraint further includes a spring. The cargo restraint further includes a locking pawl rotatably coupled to at least one of the inner pawl or the outer pawl and to the spring, the spring configured to rotate the locking pawl from an unlocked position to a locked position
Data Source
Figure 1~2
Figure 3A~3H
AI summary
A cargo restraint includes a housing (20). The cargo restraint further includes an inner pawl (40) and an outer pawl (30) coupled to the housing and configured to rotate between a retracted position and an erected position relative to the housing (20). The cargo restraint further includes a locking pawl (60) rotatably coupled to at least one of the inner pawl or the outer pawl and configured to rotate between a locked position in which the inner pawl and the outer pawl are locked in the erected position and an unlocked position.