Hair Cutting Appliance Variable Axial Force Drive Spindle
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Solution Overview
Problem
Rotary electric shavers face issues with constant axial force leading to cutting gaps, hair pulling, increased friction, noise, wear, and shortened battery life due to the self-adaptive mechanism being prone to pollution and mechanical contact irregularities within the cutting unit.
Innovation Solution
A hair cutting appliance with a drive spindle system that delivers a variable axial force in response to torque, featuring a self-adaptive mechanism with an abutment element and surface arranged at an angle α, allowing for instantaneous adaptation of closing force without being affected by pollution and ensuring axial force is centered, reducing friction and self-locking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the closing force is increased to prevent cutting gaps and hair pulling, then cutting performance is improved, but friction increases leading to noise, wear, and shortened battery life
Solution Approach 1:
The patent implements a dynamic closing force mechanism where the pressure between the cutting element and shaving cap automatically adjusts based on operational conditions. The spring-loaded system allows the closing force to vary within a range, increasing when needed for cutting and decreasing to reduce friction and energy consumption, thus resolving the contradiction between cutting performance and battery life.
2Reliability
If a self-adaptive mechanism with helical surfaces is used to vary closing force based on torque, then cutting performance is improved, but the mechanism is exposed to pollution from hair particles and skin grease causing mechanical contact irregularities
Solution Approach 1:
The patent removes the self-adaptive mechanism from the cutting unit and relocates it to the drive system. This extraction separates the pollution-exposed cutting elements from the force-adjustment mechanism, protecting the latter from hair particles and skin grease while maintaining the adaptive closing force functionality through the spring-loaded drive mechanism.
3Reliability
If the self-adaptive mechanism is contained within the cutting unit to adjust closing force, then cutting performance is improved, but the mechanism is confined to a very small space making it prone to mechanical contact irregularities
Solution Approach 1:
The patent extracts the force-adjustment mechanism from the constrained cutting unit space and relocates it to the drive system. This provides adequate space for the spring-loaded mechanism to operate without mechanical interference, eliminating contact irregularities while preserving the adaptive closing force capability through the drive spindle system.
4Reliability
If coupling spindles are used to transfer rotary power and exercise axial force, then the cutting pre-tension remains within a functionally acceptable window, but the axial force remains approximately constant rather than being optimally adaptive
Solution Approach 1:
The patent transforms the static coupling spindle into a dynamic system by incorporating a spring-loaded mechanism. The spring allows the axial force to dynamically adjust based on torque variations and operational conditions, maintaining stability within an acceptable window while providing optimal adaptability to different cutting scenarios.
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 provides improved cutting performance, reduced wear and energy loss, and extended battery life by automatically adjusting the closing force based on torque, while maintaining cleanliness and preventing self-locking, ensuring consistent and efficient operation.
Implementation Method 1
the abutment surface and the abutment element arranged to cooperate with the abutment surface for transmitting, during operation, the driving torque from the first spindle part to the second spindle part
Data Source
AI summary
A hair cutting appliance comprises an external cutting member and an internal cutting member arranged rotatable to the external cutting member for cutting hair. The internal cutting member is driven via a first coupling element by a drive spindle (24) rotatable about an axis of rotation (35) and having a first spindle part (26) arranged to be driven by a drive, and a second spindle part (30) arranged to be coupled to the internal cutting member, the first and second spindle parts (26, 30) being displaceable relative to each other in an axial direction parallel to the axis of rotation (35); wherein the second spindle part (30) comprises a second coupling element (34) which is coupled to the first coupling element for transmitting, during operation, a driving torque about the axis of rotation (35) from the drive spindle (24, 24a) to the internal cutting member; wherein one of the first and second spindle parts (26, 30) comprises an abutment element (36) and the other of the first and second spindle parts (26, 30) comprises an abutment surface (38) arranged to cooperate with the abutment element (36) for transmitting, during operation, the driving torque from the first spindle part (26) to the second spindle part (30); wherein the abutment surface (38) is arranged at an angle α relative to a tangential direction relative to the axis of rotation (35), wherein 0°<α<90° such that a transmission of the driving torque from the first spindle part (26) to the second spindle part (30) via the abutment element (36) and the abutment surface (38) results in a force exerted by the first spindle part (26) on the second spindle part (28) having a component parallel to the axis of rotation (35) and directed towards the internal cutting member, wherein the first and second coupling elements are configured to transmit the component from the second spindle part (30) to the second coupling element (34).