Shape Memory Polymer Gear Wheel for Transmission Switching

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Solution Overview

Problem

Current gear wheels in transmissions lack a simple and cost-effective method for quickly switching on or off processes, typically relying on electronic controls and mechanical clutches, which can be complex and inefficient.

Innovation Solution

A gear wheel formed from thermoplastic polymers with shape memory and thermoresponsive properties that can be programmed to change shape between a toothed or worm wheel configuration and a cylindrical or conical form upon temperature changes, allowing for reversible switching between engaged and disengaged states.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If electronic control devices and mechanical clutches are used to switch transmission processes on and off, then the switching function is achieved, but the device complexity increases

Engineering Contradiction:
Improveswitching capabilityVSAvoidcontrol system complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent combines the switching function directly into the gear wheel by integrating shape memory polymer material that can reversibly change between engaged (toothed) and disengaged (cylindrical) states. This merges the previously separate functions of the gear wheel (transmission) and clutch (switching) into a single component, eliminating the need for separate electronic controls and mechanical clutches.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The gear wheel utilizes temperature-induced parameter changes in the shape memory polymer material to achieve switching. By changing the temperature parameter, the material transitions between its permanent form (with teeth for engagement) and temporary form (cylindrical for disengagement), enabling simple thermal control of the transmission switching function.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If traditional mechanical clutches are used for switching, then the transmission can be decoupled, but the cost and structural complexity increase

Engineering Contradiction:
Improvetransmission control flexibilityVSAvoidmechanical structure complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The gear wheel transitions from a static mechanical structure to a dynamic shape-changing structure. The shape memory polymer allows the gear wheel to dynamically alter its geometry (from toothed to cylindrical form) in response to temperature changes, providing transmission control flexibility without complex mechanical moving parts.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent replaces the traditional mechanical clutch system with a thermally-actuated shape memory polymer system. Instead of using mechanical engagement and disengagement mechanisms, the invention uses temperature-induced phase transitions in the polymer to achieve the same clutching function, simplifying the mechanical structure.

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

3Productivity

If shape memory polymers are used to create reversible gear wheel forms, then switching speed improves, but the manufacturing complexity increases

Engineering Contradiction:
Improveswitching speedVSAvoidpolymer processing complexity
Core Design Contradiction:
ProductivityVSEase of manufacture

Solution Approach 1:

The invention exploits the phase transition properties of shape memory polymers between crystalline and amorphous states. By heating the polymer above its switching temperature, the material transitions to an amorphous state allowing deformation to the cylindrical form. Upon cooling, it transitions back to crystalline state, recovering the toothed gear form. This phase transition mechanism enables rapid switching while the processing steps follow conventional thermoplastic manufacturing methods.

Inventive Principle:
Principle #36Phase transitions

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

Enables rapid and efficient switching of transmission processes by converting between toothed and non-toothed states, enhancing control and reducing complexity in transmission operations.

Implementation Method 1

the at least one plasticizable polymer is at least one thermoplastic polymer with shape memory properties and/or with thermoresponsive properties, which has switching segments and interconnecting network points, wherein the polymer is programmable by deformation from a permanent shape into a temporary shape and can be deformed back from the temporary shape into the permanent shape by heating at least to the switching temperature

Methodology Applied
Scientific EffectShape memory effect: Shape Memory Polymer

Implementation Method 2

when such a mechanically deformed shape-memory polymer, 'programmed' in this way, is heated to a specific temperature, namely its switching temperature, the soft segments (switching segments) revert to their amorphous form

Methodology Applied
Scientific EffectThermal heating: Heating

Implementation Method 3

the phase transition (glass transition or melting transition) of the soft or switching segments occurs. At such a temperature, the polymer is then deformed, after which it is cooled to its so-called shape-fixing temperature, which corresponds to the crystallization temperature or glass transition temperature of the soft or switching segments

Methodology Applied
Scientific EffectPhase transition: Phase Change

Data Source

PatentEP3564023B1Gear wheel, method for its preparation and transmission comprising such a gear wheel
Publication Date: 2020.12.02 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV
  • EP3564023B1 patent drawingFigure 1(a)~3

AI summary

A gear wheel, which is formed, at least in its circumferential region, from a plasticizable polymer. The invention provides that the plasticizable polymer is a thermoplastic polymer with shape-memory properties and/or with thermoresponsive properties, which has switching segments and interconnecting network points, wherein the polymer can be programmed by deformation from a permanent shape into a temporary shape and can be deformed back from the temporary shape into the permanent shape by heating, at least to the switching temperature. The invention further relates to a gearbox with such a gear wheel and to a method for its manufacture.