Mechanical Oral Cleaning Drive With Energy Recovery

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Solution Overview

Problem

Existing sonic toothbrush technologies are costly due to electro-magnetic drivers, while mechanically-driven toothbrushes operate at lower speeds, and existing oral irrigators require separate handles for toothbrush and irrigation functions.

Innovation Solution

A toothbrush system with a motor, eccentric drive shaft, and power train assembly that converts continuous rotation into oscillating motion, incorporating energy-conserving features like compressible bumpers and flexible wings to reduce power consumption and stress, and a single handle for both toothbrush and irrigation functions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If electro-magnetic drivers are used to create oscillating toothbrush motion, then the toothbrush achieves desired oscillating output motion, but the production cost increases significantly

Engineering Contradiction:
Improveoscillating output motionVSAvoidproduction cost
Core Design Contradiction:
SpeedVSEase of manufacture

Solution Approach 1:

The patent replaces the electro-magnetic drive system with a mechanically-driven system using a continuous rotation motor coupled with a drive assembly (crank mechanism, cam-follower, or four-bar linkage) to generate oscillating motion. This substitution maintains the desired oscillating output motion while significantly reducing production cost by eliminating complex electro-magnetic components.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Ease of manufacture

If mechanically-driven systems are used to provide oscillating output brush motion, then the manufacturing cost is reduced, but the oscillating function operates at lower speeds

Engineering Contradiction:
Improvemanufacturing costVSAvoidoscillating function speed
Core Design Contradiction:
Ease of manufactureVSSpeed

Solution Approach 1:

The patent employs dynamic elements in the drive assembly including springs that store and release energy during the oscillation cycle, and inertial elements that maintain momentum. The spring-loaded follower and energy conservation mechanisms enable the mechanically-driven system to achieve higher oscillating speeds by utilizing elastic potential energy storage and release, overcoming the speed limitation of purely mechanical linkages.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The drive assembly utilizes periodic action through the oscillating conversion mechanism where the continuous rotation of the motor is transformed into periodic oscillating motion of the brush head. The drive assembly components (crank, cam, or four-bar linkage) create rhythmic back-and-forth motion at controlled frequencies, enabling the brush to operate at effective cleaning speeds while maintaining mechanical drive simplicity.

Inventive Principle:
Principle #19Periodic action

3Reliability

If separate handles are used for toothbrush and irrigation functions, then each function has its own dedicated unit, but the device complexity and size increase

Engineering Contradiction:
Improvededicated function unitsVSAvoidnumber of handles
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the toothbrush handle and irrigation handle into a single integrated handle structure. The powertrain assembly and motor are shared between both functions, while the brush head and irrigation tip can be selectively attached or used simultaneously. This consolidation reduces device complexity and eliminates the need for two separate handles while maintaining reliable dedicated function units through modular attachment interfaces.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The single handle is designed with universal functionality to perform both toothbrush and irrigation operations. The powertrain assembly provides oscillating motion that can drive either the brush head or the irrigation tip mechanism. The handle structure incorporates mounting interfaces and fluid pathways that support multiple functions, allowing users to switch between or combine brushing and irrigation modes without requiring separate devices.

Inventive Principle:
Principle #6Universality (Multi-functionality)

4Productivity

If continuous rotation motors are used to drive the oscillating mechanism, then the system operates continuously, but energy consumption increases

Engineering Contradiction:
Improvecontinuous operationVSAvoidpower consumption
Core Design Contradiction:
ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent incorporates springs and energy conservation mechanisms that store energy during the deceleration phase of the oscillation cycle and release it during the acceleration phase. This beforehand cushioning through elastic energy storage reduces the peak power demands on the motor, allowing continuous operation at lower average power consumption by smoothing out energy requirements throughout the oscillation cycle.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The drive assembly recovers and reuses energy that would otherwise be lost during the oscillating motion. The spring-loaded follower mechanism captures kinetic energy during the return stroke and converts it back into useful work during the forward stroke. This energy recovery system reduces overall power consumption while maintaining continuous productive operation of the brush.

Inventive Principle:
Principle #34Discarding and recovering

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 system provides oscillating toothbrush motion at sonic speeds with reduced power consumption, extended battery life, and a compact, cost-effective design combining toothbrush and irrigation functions in a single handle.

Implementation Method 1

The conservation features include at least one compressible bumper configured to absorb and reapply energy to the output shaft while the output shaft is oscillating

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

The conservation features include at least one flexible wing configured to absorb and reapply energy to the output shaft while the output shaft is oscillating

Methodology Applied
Scientific EffectFlexibility: Elasticity

Implementation Method 3

The power train assembly converts rotation of the eccentric drive shaft into an oscillating movement of the output shaft

Methodology Applied
Scientific EffectMechanical conversion: Mechanical Advantage

Data Source

PatentEP4382075B1Oral cleaning device with energy conservation
Publication Date: 2025.10.15 WATER PIK INC
  • EP4382075B1 patent drawingFigure 1A~1C
  • EP4382075B1 patent drawingFigure 2A~2C
  • EP4382075B1 patent drawingFigure 3A~3C

AI summary

A brushing device including a motor having an eccentric drive shaft, an output shaft operably connected to the motor, and a power train assembly coupled between the eccentric drive shaft and the output shaft. The power train converts rotation of the eccentric drive shaft into an oscillating movement of the output shaft. The power train includes one or more conservation features that absorb energy when the output shaft rotates in a first direction and reapply energy to the output shaft when it rotates in a second direction.