Pivoting Razor Handle Cam Structure for Cartridge Stability

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Solution Overview

Problem

Conventional multi-axial pivoting razors fail to provide stable shaving due to inadequate rotational resistance and recovery force, leading to the razor cartridge dangling and ineffective vertical pivoting.

Innovation Solution

A razor assembly design that incorporates a plunger with a cam action mechanism, providing rotational resistance at the rest position and concentrated recovery force in one direction when deviated, using a plunger side cam surface and head side cam surface to stabilize the razor cartridge.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the cam surface of the plunger and the cam surface of the razor cartridge are configured to make a point contact at a single point, then the structure is simple, but the razor cartridge does not remain fixed at a position and dangles

Engineering Contradiction:
Improvecam surface contact structureVSAvoidrazor cartridge position stability
Core Design Contradiction:
Device complexityVSStability of the object's composition

Solution Approach 1:

The plunger's cam surface is designed with asymmetric curvature - a first cam surface with a first curvature radius and a second cam surface with a second curvature radius that is greater than the first curvature radius. This asymmetric design allows the cam surfaces to contact at two symmetrical points in the rest position, providing rotational resistance and stabilizing the razor cartridge, while allowing single-point contact during pivoting for effective recovery force.

Inventive Principle:
Principle #4Asymmetry

2Stability of the object's composition

If the cam surface of the plunger and the cam surface of the razor cartridge are arranged to contact each other at two symmetrical points, then rotational resistance is provided at the rest position, but moments are generated at the respective contact points in opposite directions of rotation when deviated from the rest position

Engineering Contradiction:
Improverotational resistance at rest positionVSAvoidrecovery force effectiveness
Core Design Contradiction:
Stability of the object's compositionVSForce

Solution Approach 1:

The cam surfaces are designed with different curvature radii tailored to specific functional zones: the first cam surface has a smaller curvature radius optimized for providing rotational resistance at the rest position, while the second cam surface has a larger curvature radius optimized for providing recovery force during pivoting motion. This local quality differentiation resolves the contradiction between stability and force effectiveness.

Inventive Principle:
Principle #3Local quality

3Stability of the object's composition

If the cam surfaces contact at two points even when deviated from the rest position, then rotational resistance is maintained, but part of the elastic force by the spring of the plunger is used to generate moment in the direction opposite to the direction of the recovery force

Engineering Contradiction:
Improvecontinuous rotational resistanceVSAvoidspring elastic force utilization efficiency
Core Design Contradiction:
Stability of the object's compositionVSLoss of energy

Solution Approach 1:

The cam surface contact configuration dynamically changes based on the razor cartridge's position: at the rest position, two-point contact provides rotational resistance for stability; during pivoting motion, the geometry transitions to single-point contact, allowing the spring's elastic force to be fully utilized for recovery without generating opposing moments. This dynamic adaptation eliminates energy loss.

Inventive Principle:
Principle #15Dynamics

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 stable shaving by maintaining the razor cartridge's position at the rest position and effectively providing recovery force during deviations, enhancing shaving efficiency and stability.

Implementation Method 1

a plunger side cam surface and a head side cam surface to stabilize the razor cartridge

Methodology Applied
Scientific EffectCam action: Cam

Implementation Method 2

an elastic member (144) disposed inside the plunger housing (142)

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP4252982B1Razor handle and razor assembly using the same
Publication Date: 2025.12.24 DORCO CO LTD
  • EP4252982B1 patent drawingFigure 1
  • EP4252982B1 patent drawingFigure 2
  • EP4252982B1 patent drawingFigure 3~4

AI summary

A razor handle includes a handle body including a head adapter and a grip portion extending from the head adapter; a connecting head configured to be coupled to a razor cartridge and coupled to the head adapter head so as to be pivotable around a rotational axis, the connecting head including a head side cam surface on one side thereof; and a plunger disposed on one side of the handle body and including a plunger side cam surface configured to perform a cam action with the head side cam surface, the plunger being configured to provide, through the cam action, recovery force to restore the connecting head to a rest position, wherein a contact area between the head side cam surface and the plunger side cam surface is smaller when the connecting head is deviated from the rest position than when the connecting head is in the rest position.