Rotary Shaver Cutter Assembly Independent Float Mechanism
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Solution Overview
Problem
Conventional rotary electric shavers with movable outer cutters and hinged cutter circumferential rims suffer from excessive pressure on the skin, leading to discomfort and reduced shaving area due to interlocking movements and increased resistance, which limits the outer cutter's size and shaving efficiency.
Innovation Solution
The integration of an outer cutter assembly with a pushup plate and an outer cutter float spring allows each outer cutter assembly to move independently, eliminating the need for a hinge structure, enabling larger diameters and smoother movement without interference between adjacent cutters, thus enhancing shaving performance and area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the outer cutter is made movable relative to the cutter circumferential rim to reduce contact pressure, then the contact pressure on skin is reduced, but the outer cutter edge is easily caught by the mounting port rim
Solution Approach 1:
The outer cutter assembly is segmented into the outer cutter, cutter circumferential rim, and mounting port as separate functional elements. The outer cutter is retained by the cutter circumferential rim through the outer cutter retaining groove, while the assembly as a whole moves relative to the mounting port, separating the retention function from the movement function to prevent catching
Solution Approach 2:
The outer cutter retaining groove acts as an intermediary structure between the outer cutter and the mounting port. It provides a controlled retention mechanism that allows the outer cutter to move vertically and rock while preventing it from being caught by the mounting port rim, mediating between the need for movement and the need for stable retention
2Stability of the object's composition
If adjoining cutter circumferential rims are connected with a hinge to maintain smooth shaving surface, then the shaving surface smoothness is improved, but each cutter circumferential rim cannot move independently
Solution Approach 1:
Each cutter circumferential rim is segmented as an independent assembly that can move and rock independently. The cutter frame provides the structural basis for independent movement, while the cutter circumferential rims are positioned to maintain smooth shaving surface contact without mechanical connection, allowing each to adapt independently to skin contours
Solution Approach 2:
The solution moves from a mechanical connection (hinge) in the horizontal plane to a spatial arrangement where independent vertical and rocking movements are permitted. Each cutter circumferential rim operates in its own movement dimension, allowing independent adaptation to skin surface variations while maintaining overall shaving surface smoothness
3Strength
If more members interlock with the vertical movement of outer cutter to provide support, then the structural support is improved, but the resistance to vertical travel increases
Solution Approach 1:
The complex interlocking member structure is extracted and replaced with a simplified retention mechanism. The outer cutter retaining groove provides necessary structural support through its geometry alone, eliminating the need for additional interlocking members that would increase resistance to vertical movement
Solution Approach 2:
The retention mechanism parameters are optimized to provide adequate support with minimal resistance. The groove dimensions and shape are designed to retain the outer cutter securely while allowing smooth vertical movement and rocking, changing the geometric parameters to balance support strength with movement freedom
4Area of moving object
If the outside diameter of the outer cutter is increased to enlarge shaving area, then the shaving area is increased, but the size of the cutter frame must be increased
Solution Approach 1:
The cutter frame is designed with dynamic clearance that accommodates the outer cutter assembly's vertical movement and rocking. This dynamic design allows the outer cutter to have a larger outside diameter for increased shaving area without requiring a proportionally larger cutter frame, as the frame size is determined by the movement envelope rather than just the cutter diameter
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
This design prevents the outer cutter from being caught by the mounting port, allows independent movement of each cutter assembly, reduces resistance, and accommodates height differences, resulting in a larger shaving area with improved comfort and efficiency.
Implementation Method 1
an outer cutter float spring which is compressively interposed between the cutter retaining plate and the pushup plate to impart an upward restoring tendency to the pushup plate
Data Source
AI summary
A rotary electric shaver provided with a plurality of cutter units, each of which has an outer cutter (72) and an inner cutter (84), which rotates while elastically contacting the outer cutter from below. The shaver comprising: a plurality of outer cutter assemblies (70), each of which is made integral with a cutter circumferential rim (74) having the outer cutter of each cutter unit secured thereto and which is movably retained in a mounting port formed in the cutter frame (66), a pushup plate (92) which contacts the outer cutter assembly from below to push up the outer cutter assembly, a cutter retaining plate (90) which is retained by the cutter frame and which is positioned below the pushup plate, and an outer cutter float spring (94) which is compressively interposed between the cutter retaining plate and the pushup plate to impart an upward return tendency to the pushup plate. Each outer cutter can independently move, thus ensuring smooth vertical movement or rocking of the outer cutter and also permitting an increased shaving area.