Seating system having pressure compensating fluid with thermal absorption and distribution properties
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Solution Overview
Problem
Conventional fluid-filled seat cushions for personal mobility vehicles, such as wheelchairs, do not effectively promote heat movement away from the user, leading to discomfort due to inadequate heat and moisture management.
Innovation Solution
A seat cushion with a flexible polymer envelope containing a thixotropic fluid that includes a base fluid, an encapsulated phase change medium with a temperature range of 20-40°C, and a thermal conduction medium like graphite, which enhances thermal conduction and viscosity to provide both pressure relief and thermal regulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional thixotropic fluid is used in the seat cushion, then the cushion provides pressure relief and support, but the heat movement from the user into the fluid is insufficient
Solution Approach 1:
The patent applies composite materials by combining thixotropic fluid with phase change material (PCM) and thermal conduction medium. The thixotropic fluid provides pressure relief and support, while the PCM (microencapsulated paraffin) absorbs and releases heat through phase changes, and the thermal conduction medium (graphite or metal particles) enhances heat transfer. This composite fluid system simultaneously achieves pressure compensation and improved thermal management without requiring separate mechanical components.
Solution Approach 2:
The patent utilizes phase transitions of the phase change material (paraffin) to manage heat. The PCM undergoes phase changes between solid and liquid states within the physiological temperature range (20-40°C), absorbing heat when the user's body temperature rises and releasing heat when the temperature drops, thereby maintaining thermal comfort and improving heat movement capability dynamically.
2Stress or pressure
If the fluid viscosity is increased to improve support, then pressure relief is enhanced, but thermal conduction capability decreases
Solution Approach 1:
The composite fluid system resolves this contradiction by assigning different functions to different components: the thixotropic fluid (with viscosity 10,000-300,000 cP) provides pressure relief and support, while the thermal conduction medium (graphite particles, metal particles, or carbon nanotubes) embedded in the fluid provides thermal conduction pathways. The phase change material handles thermal regulation through phase transitions. This functional separation allows high viscosity for support without compromising thermal conduction.
Solution Approach 2:
The thermal conduction medium acts as an intermediary substance that bridges the gap between the high-viscosity thixotropic fluid and the heat transfer requirement. These particulate materials (graphite, metal particles, carbon nanotubes) create conductive networks within the viscous fluid, enabling efficient heat transfer despite the fluid's thick consistency, thus mediating between support and thermal conduction needs.
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 effectively manages heat and moisture, providing increased comfort by maintaining a cooler surface temperature over time, even after prolonged use, and supports user weight without focusing pressure on sensitive areas.
Implementation Method 1
an encapsulated phase change medium having a phase change temperature between a solid phase and a liquid phase within a range of 20 degrees Celsius to 40 degrees Celsius
Implementation Method 2
a thermal conduction medium. The thermal conduction medium is a micro-sized particulate material having a particle size 1 micron or less
Implementation Method 3
The resulting thixotropic fluid provides support by conforming to the contours of contacted body parts, deforms in response to a continuously applied pressure, and maintains the deformed shape and position
Data Source
Figure 1
Figure 2A~2B
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AI summary
A seating system, particularly suited for personal mobility vehicles, such as wheelchairs, that includes a seat cushion having pressure relieving properties and enhanced thermal absorption properties. The seat cushion includes a thixotropic fluid contained within a flexible envelope. The thixotropic fluid includes a phase change material that enhances the thermal absorption properties of the seat cushion to increase thermal absorption from a seated user to provide a reduced temperature sensory effect. The thixotropic fluid further includes a thermal conduction medium that facilitates heat distribution to the phase change material.