Canard Fin Deployment Device with Spiral Spring Torque
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Solution Overview
Problem
Conventional canard fin deployment devices for guided projectiles suffer from insufficient or variable pivoting torque, leading to opening asymmetries and unreliable locking mechanisms, particularly during fin rebound, which can result in partial deployment.
Innovation Solution
A device utilizing a spiral spring loop arranged parallel to the fin's deployment axis, combined with a tilting lever and compression springs, to provide consistent pivoting torque and secure locking, along with an inductive position sensor for precise detection of the locking position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spiral torsion spring is used for fin deployment, then the fin can be deployed, but the pivoting torque is insufficient or variable leading to opening asymmetries
Solution Approach 1:
The single torsion spring is divided into two separate torsion springs, each mounted on its own axis. This segmentation allows each spring to independently provide consistent torque to its respective fin, eliminating the torque variability and asymmetry problems that occurred with a single shared spring mechanism.
Solution Approach 2:
Two lever arms are introduced as intermediary elements between the torsion springs and the fins. Each lever is actuated by its own torsion spring and transfers the rotational force to the corresponding fin. This intermediary mechanism ensures consistent force transmission and reliable deployment while allowing independent control of each fin's pivoting torque.
2Reliability
If a pin and indentation locking mechanism is used, then locking is provided, but rebound causes unreliable locking and partial deployment
Solution Approach 1:
The lever arms are designed with inclined locking surfaces that engage the fin arms in advance of the final deployed position. As the fins deploy, the levers pivot and their ends engage the fins at an angle, creating a progressive locking action that prevents rebound before the fin reaches its full deployed position, ensuring stable final positioning.
3Ease of manufacture
If the deployment device is simplified, then manufacturing is easier, but detection of locking position becomes less precise
Solution Approach 1:
Optical detection elements are incorporated into the lever arm structure to provide visual or optical signals indicating the locked position. These elements may change optical properties (such as reflectivity, transparency, or color) when the lever reaches its locked position, enabling precise detection without adding complex mechanical sensors or indicators to the deployment mechanism.
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
Ensures reliable and symmetrical opening and locking of canard fins, preventing rebound and facilitating accurate detection of the deployed position for enhanced projectile control.
Implementation Method 1
The deployment means comprises a first means exerting a pivoting torque on the fin (2) and constituted by a spiral spring coaxial with the axis (3)
Implementation Method 2
These springs 13 are just positioned in the figures to identify their location. They are arranged in holes integral with a part of the projectile body. The holes guide the springs 13 during their compression and the bottom of each hole forms a bearing surface for the spring.
Implementation Method 3
A position sensor may be arranged close to the support finger and will detect the passage of the latter to its locking position of the fin.
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 3a~3b
AI summary
The device has a motor unit for pivoting a canard fin (2) from a transport position to a deployed position, where the fin is arranged inside a body (7) of a projectile (1) in the transport position and arranged radial to the body of the projectile in the deployed position. The motor unit comprises a support finger (12) that exerts a pivoting torque directly on an arm (2b). The support finger comprises a locking stop for the arm when the fin is in the deployed position, where a position sensor is arranged close to the support finger and detects passage of a loop of a spiral spring.