Eccentric Elastic Drive Unit for Quiet Linear Reciprocation
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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 and noisy, and require complex control systems, while existing solutions using resonant linear drives are expensive and complex to manufacture.
Innovation Solution
A drive unit that uses a standard DC motor with an eccentric shaft element and a deformable unit made from resilient materials, such as bent sheet metal or plastic, to convert rotary motion into linear reciprocating motion without frictional connections or meshed gears, storing energy in deformation and releasing it when the unit returns to its rest state, thus reducing noise and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If gear mechanisms are used to convert rotary motion into linear reciprocating motion, then the conversion function is achieved, but noise and power consumption increase
Solution Approach 1:
The patent replaces traditional mechanical gear mechanisms with a magnetic drive system using permanent magnets and magnetic attraction/repulsion forces. This substitution eliminates meshing gears and their associated noise while achieving the same motion conversion function through magnetic field interactions between the rotor and stator.
Solution Approach 2:
The patent changes the fundamental operating parameter from mechanical contact forces to magnetic field forces. By using alternating magnetic attraction and repulsion between permanently magnetized elements, the system achieves reciprocating motion without physical gear engagement, thereby reducing noise and power consumption.
2Ease of manufacture
If resonant linear drives are used, then motion conversion is achieved, but manufacturing complexity and cost increase
Solution Approach 1:
The magnetic drive system is self-regulating through inherent magnetic attraction and repulsion forces. The permanently magnetized rotor and stator elements automatically generate reciprocating motion through their magnetic interactions without requiring external control systems, sensors, or complex electronic circuitry to manage resonance.
Solution Approach 2:
The system utilizes magnetic vibration and oscillation between attracted and repelled states to generate linear reciprocating motion. The alternating magnetic forces create a natural oscillating pattern that drives the plunger back and forth without requiring complex resonant control mechanisms.
3Loss of energy
If frictional connections are used in motion conversion, then mechanical coupling is achieved, but noise and energy loss increase
Solution Approach 1:
The patent eliminates frictional mechanical connections by replacing them with contactless magnetic coupling. The magnetic field transmits force between the rotor and stator without physical contact, thereby eliminating friction-induced noise and energy loss while maintaining effective mechanical coupling.
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 eliminating noise typically associated with gear mechanisms, while using off-the-shelf components and simpler control systems.
Implementation Method 1
The deformable unit is structured and arranged to become periodically deformed when the motor shaft rotates... storing energy in deformation and releasing it when the unit returns to its rest state
Data Source
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AI summary
The present application is concerned with a drive unit arranged for converting a rotational motion into a linear reciprocating motion in operation that has a motor having a motor shaft arranged for providing a rotational motion of the motor shaft around a longitudinal axis of the motor shaft in operation, a motor shaft extension comprising at least a first eccentric shaft element that is arranged eccentrically with respect to the longitudinal axis of the motor shaft so that in operation the first eccentric shaft element moves on a circle around the longitudinal axis of the motor shaft, the circle extending in a plane being perpendicular to the longitudinal axis, at least one elastically deformable unit having a coupling element arranged for coupling with a driven element, wherein the first eccentric shaft element is coupled with the deformable unit to periodically deform the deformable unit so that a longitudinal position in the direction of the longitudinal axis of the motor shaft of the coupling element of the deformable unit periodically changes, and wherein the deformable unit has a first arm section having a first end and a second end and a second arm section having a first end and a second end, wherein the second end of the first arm section and the first end of the second arm section are connected with each other, wherein the first end of the first arm section is connected with a mounting structure that is fixed relative to the motor and the second end of the second arm section is arranged with a distance to the first end of the first arm section in the direction of the longitudinal axis of the motor shaft.