Push Button Motion Indicator Mechanism for Compact Jam Detection
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Solution Overview
Problem
Current jam indicators for aircraft control surface drive mechanisms require large indicator arms and are prone to false indications due to spring clip failures, necessitating a more compact and reliable solution.
Innovation Solution
A motion indicator mechanism featuring a push button and plunger system with a retaining assembly using retaining balls and springs to indicate overtorque or jam conditions, housed within a compact design to prevent exposure to harsh environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a lever type mechanism with a pivoted indicator arm is used, then the jam condition can be indicated, but the housing size increases and false indications may occur due to spring clip failure
Solution Approach 1:
The indicator mechanism is segmented into distinct functional components: a plunger that detects torque limiter movement, a retaining assembly with retaining balls that holds the push button, and a push button that provides visual indication. This segmentation eliminates the need for a large pivoted arm while maintaining reliable indication functionality.
Solution Approach 2:
Instead of using a spring clip to retain the indicator arm (which can fail), the invention inverts the retention mechanism by using retaining balls held by disc springs to retain the push button. This inversion provides more reliable retention without requiring large moving parts.
2Ease of operation
If a large indicator arm is used for visual inspection, then the jam indication is noticeable, but the housing size increases
Solution Approach 1:
The indication mechanism transitions from a lateral movement system (pivoted arm moving side-to-side) to an axial movement system (push button moving in-and-out). This dimensional change allows for compact housing while maintaining visual detectability, as the push button's axial movement can be clearly observed without requiring large arm length.
Solution Approach 2:
While not explicitly using color changes, the push button provides visual indication through positional change that is equally detectable. The button's movement between retracted and extended positions serves the same visual notification function as a large indicator arm would, but in a compact form factor.
3Volume of stationary object
If a spring clip is used to retain the indicator arm, then the mechanism can be compact, but false jam indications may occur due to spring clip failure
Solution Approach 1:
The retaining assembly uses disc springs and retaining balls as replaceable retention elements. These components are designed to be simple, robust, and easily replaceable, providing reliable retention without the complexity and failure-proneness of spring clips. The system prioritizes reliability through simplicity and ease of maintenance.
Solution Approach 2:
The retaining assembly is designed with disc springs that provide controlled retention force, preventing accidental release of the push button. This beforehand cushioning through proper spring selection and retention geometry ensures that normal operational vibrations or forces cannot cause false indication, while still allowing intentional reset.
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 mechanism provides a compact, reliable, and visually clear indication of overtorque or jam conditions, reducing false alarms and maintaining indicator integrity without increasing the mechanism's volume or weight.
Implementation Method 1
The plunger is biased into an axially extended position relative to the housing via a plunger biasing element
Implementation Method 2
The push button is biased toward an axially extended position relative to the housing via a biasing element
Implementation Method 3
The one or more retaining elements includes one or more disc springs
Implementation Method 4
The one or more retaining elements includes one or more tine springs
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A motion indicator includes a housing (36) and a plunger (56) extending from a first housing end of the housing (36) and axially movable relative to the housing (36). The plunger (56) is biased into an axially extended position via a plunger biasing element, and is configured to detect motion of a component adjacent to a plunger tip. A push button (42) is located at a second housing end of the housing (36) and is axially moveable relative to the housing (36). The push button (42) is biased toward an axially extended position via a biasing element. A retaining assembly is configured to retain the push button (42) in an axially retracted position. The retaining assembly is configured to release the push button (42) and allow the button biasing element to urge the push button (42) toward the axially extended position when the plunger (56) is urged toward a retracted position via motion of the component adjacent to the plunger tip.