Multi-Directional Input Shaft Support for Compact Rotation Range
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Solution Overview
Problem
Conventional multi-directional input devices face challenges in reducing the overall height while increasing the rotation radius of the operation shaft, and ensuring sufficient strength at the snap-engaging portion between the operation shaft and the lower arm, which complicates assembly.
Innovation Solution
The device incorporates an upward convex spherical trapezoidal portion at the lower end of the operation shaft, supported by a receiving portion with a matching curvature in the case, allowing the operation shaft to rotate without coming off, and an actuating member with a protrusion in a vertical guide groove to regulate rotation, along with a compression coil spring to return the shaft to a neutral state, enhancing strength and assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the rotation radius of the operation shaft is increased, then the operation range and control precision are improved, but the entire height of the device increases
Solution Approach 1:
The operation shaft is designed with a spherical trapezoidal portion at its lower end that fits into a corresponding spherical receiving portion in the case. This spherical configuration allows the operation shaft to rotate with a larger effective radius while maintaining a compact vertical profile, as the spherical geometry provides rotational freedom without requiring increased height.
2Strength
If the snap-engaging portion between the operation shaft and lower arm is strengthened, then the assembly strength is improved, but the device complexity increases
Solution Approach 1:
The snap-engaging portion is integrated directly into the lower arm structure, merging the support function and the engagement function into a single unified component. This eliminates the need for separate fastening mechanisms while maintaining sufficient assembly strength, thereby reducing overall device complexity.
3Ease of manufacture
If the snap-engaging portion is simplified for easier assembly, then the ease of manufacture is improved, but the assembly strength decreases
Solution Approach 1:
The spherical trapezoidal portion and its receiving portion are designed with complementary geometries that naturally guide the operation shaft into proper alignment during assembly. This self-aligning feature ensures that the engagement occurs at optimal stress distribution points, achieving both ease of assembly and sufficient strength without requiring complex adjustment procedures.
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 enables the device to be downsized without compromising strength, allowing the operation shaft to rotate freely and maintain sufficient support, while also facilitating a compact design and efficient operation of electric components.
Implementation Method 1
a compression coil spring that is provided between the operation shaft and the actuating member, and presses the downward convex spherical trapezoidal portion against the bottom plate to return the operation shaft to a neutral state
Data Source
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AI summary
In a multi-directional input device, an upward convex spherical trapezoidal portion 410 is provided at a lower end of an operation shaft 400 projecting downward of a lower arm 300, a receiving portion 112 for the upward convex spherical trapezoidal portion 410 is provided in a case 100, the receiving portion 112 has a receiving surface 112a configured with a spherical surface having a radius of curvature identical to a radius of curvature of a spherical zone 411 of the upward convex spherical trapezoidal portion 410, the receiving surface 112a against which the spherical zone 411 of the upward convex spherical trapezoidal portion 410 is pressed downward by a compression coil spring 600, and the operation shaft 400 is supported to be rotatable around the center of curvature of the receiving surface 112a.