Safety Razor Handle with Pushbutton Ejection and Transfer Rod

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Solution Overview

Problem

Existing system safety razors face challenges in balancing user-perceived quality and manufacturing costs, as heavier razers are less desirable due to increased material and shipping costs, while lighter razors lack the appeal of a heavier mass.

Innovation Solution

A safety razor handle design featuring a pushbutton, transfer rod, and compression spring mechanism that allows for efficient ejection of the razor cartridge while adding mass and absorbing impact, with the transfer rod being made from materials like steel or thermoplastic polymers to enhance weight and durability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If the razor handle is made heavier to improve user-perceived quality, then the appeal and perceived performance improve, but the manufacturing costs and shipping costs increase

Engineering Contradiction:
Improvehandle massVSAvoidmanufacturing cost
Core Design Contradiction:
Weight of moving objectVSEase of manufacture

Solution Approach 1:

The handle is divided into a core structural component and a separate weight component. The weight component can be made from dense materials like metal or high-density polymer and attached to the core handle structure, allowing the mass to be added without complicating the main manufacturing process of the handle body.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The handle combines materials of different densities - typically a lighter structural material (such as plastic or aluminum) for the main handle body, and a denser material (such as metal insert or high-density polymer) for the weight component, creating a composite structure that balances cost and perceived quality.

Inventive Principle:
Principle #40Composite materials

2Device complexity

If a pushbutton is mounted at the cartridge-bearing end of the handle, then the release mechanism is compact, but the button may be accidentally operated during shaving

Engineering Contradiction:
Improverelease mechanism compactnessVSAvoidaccidental operation prevention
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

Instead of mounting the pushbutton at the cartridge-bearing end (front) of the handle, the button is inverted to the opposite end (rear). This positions the actuator away from the user's hand during shaving, eliminating accidental operation while maintaining a compact overall mechanism through the use of a long transfer rod.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

A long transfer rod acts as an intermediary element, transmitting the actuating force from the pushbutton at one end of the handle to the cartridge release mechanism at the other end. This allows spatial separation of the control interface from the execution point, solving both compactness and safety concerns.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Ease of operation

If a long and thin rod is used to connect the pushbutton to the release mechanism, then the button can be positioned remotely, but the rod may buckle under compression

Engineering Contradiction:
Improvebutton positioning flexibilityVSAvoidrod buckling resistance
Core Design Contradiction:
Ease of operationVSStrength

Solution Approach 1:

The transfer rod is designed with controlled flexibility - it can be slightly flexible or elastically deformable to accommodate minor misalignments and reduce stress concentrations, while still maintaining sufficient rigidity to transmit force without buckling under normal operating conditions.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The rod's structural parameters (diameter, wall thickness, material properties, or moment of inertia) are optimized to achieve the right balance between flexibility and rigidity. The rod may be made hollow or with varying wall thickness along its length to achieve desired mechanical properties while minimizing material usage.

Inventive Principle:
Principle #35Parameter changes

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 design effectively balances mass and cost by adding weight to the handle, ensuring reliable cartridge ejection and impact absorption, thus improving user experience and manufacturing efficiency.

Implementation Method 1

A compression spring is located in the hollow portion and acts between the cartridge attachment end and the first end of the transfer rod to bias the transfer rod in a direction along the axis towards the opening

Methodology Applied
Scientific EffectSpring: Spring

Implementation Method 2

A compression spring is located in the hollow portion and acts between the cartridge attachment end and the first end of the transfer rod

Methodology Applied
Scientific EffectCompression: Compression

Data Source

PatentEP3946850B1Safety razor and handle for a safety razor
Publication Date: 2023.05.03 EDGEWELL PERSONAL CARE BRANDS LLC
  • EP3946850B1 patent drawingFigure 1
  • EP3946850B1 patent drawingFigure 2
  • EP3946850B1 patent drawingFigure 3

AI summary

A safety razor handle (20) has a body (21) having a cartridge attachment end (24) with an adjoined elongated hollow portion (22) terminating in an opening (44) at an opposed end (26) of the body. A pushbutton (50) is slidably retained in the opening and movable along an axis (42) of the hollow portion between an at- rest position and a depressed position. An elongated transfer rod (60) is located in the hollow portion and has a first end (62) in the cartridge attachment end region of the hollow portion and a second end (64) closely abutting the pushbutton. A compression spring (70) acts between the cartridge attachment end and the first end of the transfer rod to bias the transfer rod along the axis towards the opening. An ejector (80) is mounted in the cartridge attachment end having an outer end (84) extendable outwardly from the cartridge attachment end and an inner end (82) closely abutting the first end of the transfer rod.