Single-Piece Rotary Shaver Inner Blade for Compact Shaft Engagement
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Solution Overview
Problem
Rotary electric shavers in the related art face increased component and assembly costs due to the use of multiple components, such as a metal inner blade and a resin inner blade holder, which also result in a larger axial height, making the device less compact.
Innovation Solution
A rotary electric shaver design featuring a single-component inner blade made of metal with a recessed portion and a radial projection, where the inner blade drive shaft engages with the concave portion, allowing for a compact configuration and simplified manufacturing through press work.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If multiple components (inner blade and inner blade holder) are used to configure the inner blade assembly, then the structural stability is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent merges the inner blade and inner blade holder into a single integrated component made of metal material. The inner blade is formed as one piece with the holder structure, eliminating the need for separate components and assembly processes. This integration maintains structural stability while reducing device complexity and manufacturing cost.
2Stability of the object's composition
If multiple components are combined in the axial direction to form the inner blade assembly, then the structural integrity is improved, but the height dimension increases, making the device less compact
Solution Approach 1:
By integrating the inner blade and holder into a single component, the patent eliminates the axial spacing and interface requirements between separate parts. The unified structure achieves the same structural integrity with a reduced axial height, enabling a more compact overall device design.
3Adaptability or versatility
If multiple components are used for the inner blade assembly, then the functional requirements are met, but the assembly work and manufacturing cost increase
Solution Approach 1:
The patent integrates multiple functions into a single metal component that serves both as the inner blade and holder. This eliminates the need for separate manufacturing and assembly processes for multiple components, reducing manufacturing cost while maintaining all necessary functional requirements for blade operation and structural support.
4Device complexity
If a single component inner blade is used, then the manufacturing cost and device complexity are reduced, but the engagement mechanism with the drive shaft becomes more challenging
Solution Approach 1:
The patent incorporates an asymmetric engagement structure where a projection on the inner blade fits into a corresponding recess on the drive shaft. This asymmetric design provides reliable mechanical engagement and torque transmission while maintaining a compact single-component structure, solving the engagement challenge without increasing complexity.
Data Source
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AI summary
A rotary electric shaver (1) according to the present invention includes an outer blade (22) whose upper surface (22a) functions as annular shaving surfaces (22A and 22B) having multiple hair inlets (23) formed therein, and an inner blade (40) that has a small blade (42) which rotates while coming into sliding contact with a lower surface (22b) of the outer blade (22). The inner blade (40) is an integral structure using a metal material, and has a projection (44) in which an upper surface side is a convex portion (44a) and a lower surface side is a concave portion (44b) at a center position in a radial direction. An upper end portion (12a) of an inner blade drive shaft (12) directly engages with the concave portion (44b) so as to be disengageable therefrom.