Piezoelectric Drive With Spring Bracket for High-Torque Brush Motion
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Solution Overview
Problem
Existing piezoelectric drives in personal care appliances, such as toothbrushes, face limitations in generating high torque and efficient cleaning movements due to low forces and inhomogeneous bristle movement patterns, leading to reduced cleaning performance and increased energy consumption.
Innovation Solution
A piezoelectric drive unit with a spring bracket attached to a piezoelectric element, converting the element's change in length into a bracket stroke in a Y-direction, which is then transmitted to a rotatable shaft for rotational movement, allowing for high-torque and energy-efficient operation with minimal moving parts, enabling optimized bristle movement patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a piezoelectric element is used to generate drive movement, then energy efficiency is improved, but the generated force and torque are insufficient
Solution Approach 1:
The patent transforms the linear expansion/contraction movement of the piezoelectric element in one dimension into rotational movement in another dimension through a redirecting transmission mechanism. This dimensional transformation allows the piezoelectric element to generate effective torque for rotating the brush shaft while maintaining its energy-efficient linear actuation principle.
Solution Approach 2:
The patent introduces a redirecting transmission as an intermediary mechanism between the piezoelectric element and the brush shaft. This intermediary converts the linear motion of the piezoelectric element into rotational motion, enabling the piezoelectric element to generate sufficient torque for driving the brush while maintaining energy efficiency.
2Volume of moving object
If a round brush head rotating around an axis is used, then the moving part size is reduced, but the bristle movement becomes inhomogeneous
Solution Approach 1:
The patent segments the brush head into a round configuration that rotates around an axis, dividing the cleaning function across multiple bristle zones. This segmentation allows different parts of the brush to contact different tooth surfaces, achieving comprehensive cleaning while keeping the moving part compact.
Solution Approach 2:
The patent implements dynamic rotational movement of the round brush head around an axis, transforming the static brush configuration into a dynamic cleaning system. The rotation ensures that all bristles participate in cleaning action, achieving homogeneous bristle movement distribution across the entire bristle field while maintaining a compact design.
3Stability of the object's composition
If the brush head mass is positioned far from the pendulum axis, then homogeneous bristle movement is achieved, but large forces and moments occur
Solution Approach 1:
The patent replaces the traditional pendulum motion mechanism with a piezoelectric-driven rotational system. This substitution eliminates the need for large forces and moments associated with pendulum motion while achieving homogeneous bristle movement through controlled rotation of the brush head around an axis.
4Device complexity
If housing vibration is used to drive the brush, then motion transmission complexity is reduced, but energy consumption increases and comfort decreases
Solution Approach 1:
The patent extracts the vibration generation function from the entire housing and concentrates it in a localized piezoelectric element. This extraction allows targeted vibration delivery to the brush head without requiring the entire housing to vibrate, thereby reducing energy consumption while maintaining simple motion transmission.
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 achieves a robust, high-torque drive with efficient energy use, providing homogeneous bristle movement and improved cleaning performance while minimizing material fatigue and energy consumption.
Implementation Method 1
a piezoelectric element, whereby a change in length in an X-direction occurs upon electrical activation
Data Source
AI summary
In a handle for a personal care appliance, a drive unit includes a piezoelectric drive (100) for generating an oscillating movement. The piezoelectric drive includes a piezoelectric element (120) having first and second ends, in which a change in length in an X-direction occurs upon electrical activation, so that a distance between the first and second ends changes. A first end of a spring bracket (110) is affixed to a first end of the piezoelectric element and a second end of the spring bracket is affixed to the second end of the piezoelectric element, whereby the change in length of the piezoelectric element in the X-direction is converted into a first bracket stroke in a Y-direction. A connecting element (130) is configured to transmit the oscillating movement to the personal care device and is attached in a central region of the spring bracket for tapping the first bracket stroke.