External Cutting Member Rotation Through Integrated Shaver Transmission
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Solution Overview
Problem
Existing electric shaver designs with rotating external cutting members suffer from increased bulkiness and reduced skin contour following ability due to the need for additional driving components, which also depend on user behavior for optimal performance.
Innovation Solution
A shaving unit with rotatable external cutting members powered by an integrated transmission unit within each hair-cutting unit, using a first and second transmission member and intermediate members to convert the internal cutting member's rotation into the external cutting member's rotation, without requiring separate drive trains outside the unit, allowing for compact design and skin contour following.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If additional driving components are added to rotate the external cutting member, then hair-catching ability is improved, but device complexity and bulkiness increase
Solution Approach 1:
The patent merges the driving functions for the internal and external cutting members into a single integrated drive unit. The motor's rotation is transmitted through a transmission mechanism (including drive shaft, gear, and belt) that simultaneously drives both cutting members, eliminating the need for separate driving components and reducing overall device complexity while maintaining enhanced hair-catching ability through external cutting member rotation
Solution Approach 2:
The single motor and transmission system serve multiple functions: it drives the internal cutting member directly and, through the transmission mechanism, drives the external cutting member. This multi-functional design allows one driving system to perform what would traditionally require separate driving components, reducing bulkiness while achieving the desired hair-catching performance
2Productivity
If additional driving components are added to rotate the external cutting member, then hair-catching ability is improved, but skin contour following ability is reduced
Solution Approach 1:
The transmission mechanism is nested within the existing housing structure of the hair-cutting unit. The drive shaft, gear, and belt are arranged in a compact nested configuration that fits within the available space without increasing the external dimensions of the unit, thereby preserving the ability to follow skin contours while enabling external cutting member rotation for improved hair-catching
3Productivity
If the external cutting member is made rotatable, then more hair-entry openings are accessible, but the structure becomes bulkier
Solution Approach 1:
The patent achieves external cutting member rotation through a transmission mechanism that operates in the radial and axial dimensions rather than requiring additional lateral space. The belt-driven rotation system allows the external cutting member to rotate about its central axis without increasing the overall volume of the hair-cutting unit, maintaining compactness while improving accessibility of hair-entry openings
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 efficient hair-catching without user-dependent performance, maintaining a compact size and allowing the hair-cutting units to follow skin contours, providing a comfortable shaving experience with reduced skin irritation.
Implementation Method 1
a first transmission member (61) mounted to the internal cutting member (32) to be rotatable together with the internal cutting member (32) about the central axis (Ac); a second transmission member (62) mounted to the external cutting member (31) to be rotatable together with the external cutting member (31) about the central axis (Ac); and at least one intermediate transmission member (63, 64, 65) via which the first transmission member (61) is coupled to the second transmission member (62) to convert a rotation of the internal cutting member (32) about the central axis (Ac) into a rotation of the external cutting member (31) about the central axis (Ac)
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
In a shaving unit for an electric shaver, a hair-cutting unit (30) comprises a housing (40) having a central axis (Ac), an external cutting member (31) supported by the housing (40), and an internal cutting member (32) covered by the external cutting member (31). The external cutting member (31) is rotatable about the central axis (Ac) relative to the housing (40), and the internal cutting member (32) is rotatable about the central axis (Ac) relative to the external cutting member (31). The hair-cutting unit (30) further comprises a transmission unit (60) which is accommodated in the housing (40) and which comprises a first transmission member (61) mounted to the internal cutting member (32), a second transmission member (62) mounted to the external cutting member (31), and at least one intermediate transmission member (63, 64, 65) via which the first transmission member (61) is coupled to the second transmission member (62).