Eccentric Deformable Drive Unit for Quiet Reciprocating Motion

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Solution Overview

Problem

Existing drive units that convert rotary motion into linear reciprocating motion for personal care devices are often costly, complex, and noisy, with high power consumption and frictional losses due to gear mechanisms.

Innovation Solution

A drive unit utilizing a deformable unit with an eccentric shaft element and a linear guide to convert rotary motion into linear reciprocating motion, eliminating meshed gears and frictional connections, and using a resilient deformable unit to store and release energy, thereby reducing noise and power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-generated harmful factors

If gear mechanisms are used to convert rotary motion into linear reciprocating motion, then motion conversion is achieved, but noise and power consumption increase

Engineering Contradiction:
ImprovenoiseVSAvoidgear mechanism complexity
Core Design Contradiction:
Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The patent removes the gear mechanism entirely from the motion conversion system. Instead of using gears to convert rotary motion to linear reciprocating motion, the invention uses an eccentric shaft element directly coupled with a deformable unit that converts the rotational motion through elastic deformation, thereby eliminating the noise and complexity associated with meshed gears.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the traditional mechanical gear system with an elastomeric deformable unit that uses elastic deformation to achieve motion conversion. This substitution eliminates frictional connections and meshed gears, resulting in reduced noise, lower power consumption, and fewer frictional losses while maintaining the motion conversion function.

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

2Use of energy by moving object

If meshed gears and frictional connections are used for motion conversion, then motion transfer is achieved, but power consumption and frictional losses increase

Engineering Contradiction:
Improvepower consumptionVSAvoidfrictional losses
Core Design Contradiction:
Use of energy by moving objectVSLoss of energy

Solution Approach 1:

The patent replaces friction-based mechanical gear transmission with an elastomeric deformable unit that transfers motion through elastic deformation. This substitution eliminates frictional connections and meshed gears, resulting in reduced power consumption and minimal frictional losses while maintaining efficient motion transfer from the motor shaft to the driven element.

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

Solution Approach 2:

The deformable unit dynamically deforms and recovers during operation, storing and releasing elastic energy during each cycle. This dynamic behavior allows for efficient energy transfer without the continuous frictional losses inherent in rigid gear mechanisms, as the elastomeric material naturally absorbs and releases energy during deformation cycles.

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

The solution provides an efficient and silent conversion of rotary motion to linear reciprocating motion, reducing power consumption and noise, while maintaining a low-cost profile using standard DC motors and off-the-shelf components.

Implementation Method 1

a deformable unit (50A-50D) that is arranged to be periodically deformed when the motor shaft rotates

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

at least a first eccentric shaft element (41A-41D) that is arranged eccentric with respect to a longitudinal axis of the motor shaft

Methodology Applied
Scientific EffectEccentric motion: Eccentric

Data Source

PatentEP4050237B1Drive unit and personal care device with a drive unit
Publication Date: 2024.07.03 BRAUN GMBH
  • EP4050237B1 patent drawingFigure 1
  • EP4050237B1 patent drawingFigure 2
  • EP4050237B1 patent drawingFigure 3

AI summary

Drive unit (25A, 25B, 25D, 25E) for converting a rotational motion into a linear reciprocating motion, having a motor (30A, 30B, 30D, 30E) having a motor shaft (31A, 31B, 31D, 31, 3) for providing a rotational motion of the motor shaft (31A, 31B, 31D, 31, 3) around a longitudinal axis (A1) of the motor shaft (31A, 31B, 31D, 31, 3), a motor shaft extension (40A, 40F) having at least a first eccentric shaft element (41A, 41B, 41E, 41F, 41, 4) that is arranged eccentrically with respect to the longitudinal axis (A1) of the motor shaft (31A, 31B, 31D, 31, 3), at least one elastically deformable unit (100E, 50A, 50B, 50C, 50D, 50E, 50F, 50) having a coupling element (109E, 59A, 59B, 59C, 59F) arranged for coupling with a driven element (21), preferably wherein the coupling element (109E, 59A, 59B, 59C, 59F) is coupled with or can be coupled with a drive shaft (3, 70B, 70D, 70E), wherein the first eccentric shaft element (41A, 41B, 41E, 41F, 41, 4) is coupled with the deformable unit (100E, 50A, 50B, 50C, 50D, 50E, 50F, 50) to periodically deform the deformable unit (100E, 50A, 50B, 50C, 50D, 50E, 50F, 50) so that a longitudinal position of the coupling element (109E, 59A, 59B, 59C, 59F) of the deformable unit (100E, 50A, 50B, 50C, 50D, 50E, 50F, 50) periodically changes, preferably wherein the deformable unit (100E, 50A, 50B, 50C, 50D, 50E, 50F, 50) is an integral, single unit.