Insulating Mixing Fan for Combustible Gas-Air Mixtures
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Solution Overview
Problem
Existing mixing fans used in heating technology for conveying explosive gas-air mixtures face challenges in preventing electrostatic charging and ignition risks, with current solutions being costly, complex, and difficult to recycle due to the use of conductive materials.
Innovation Solution
A mixing fan design featuring an insulating fan wheel and housing made from single-variety plastics with high surface resistance, allowing operation without grounding, and incorporating an insulating shaft seal to minimize charge discharge, thereby eliminating the need for costly grounding mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conductive materials or grounding mechanisms are used to prevent electrostatic charging, then safety against ignition is improved, but production costs and device complexity increase
Solution Approach 1:
Instead of using conductive materials to ground and dissipate electrostatic charges, the patent inverts the approach by using insulating materials to prevent charge accumulation in the first place. The fan wheel is made from an insulating plastic material with high electrical resistance, which prevents electrostatic charging during operation, thereby eliminating the need for grounding mechanisms while maintaining safety.
2Reliability
If conductive compound materials are used for the impeller, then electrostatic safety is improved, but recyclability deteriorates
Solution Approach 1:
The patent uses homogeneous insulating plastic material for the fan wheel instead of composite materials mixed with conductive additives. This single-variety plastic material maintains uniform properties throughout, enabling straightforward recycling processes while providing sufficient electrical insulation to prevent electrostatic charging and ensure safety.
3Ease of manufacture
If insulating material is used for the fan wheel, then recyclability and cost are improved, but electrostatic charging risk increases
Solution Approach 1:
The patent addresses the electrostatic charging risk by carefully selecting insulating plastic materials with specific electrical resistance parameters. The material is chosen to have high enough resistance to prevent charge dissipation but with properties that minimize charge generation during operation. Additional design parameters such as surface finish and operating conditions are optimized to control electrostatic effects while maintaining recyclability.
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 insulating design effectively prevents electrostatic ignition risks, reducing production costs and enhancing recyclability while maintaining high mixing efficiency and heat output, as the fan operates safely without grounding, even at high speeds and with high dust particle concentrations.
Implementation Method 1
the fan wheel which is designed to be insulating... A substance or material with a specific resistance of ρ ≤ 10 4Ωm is referred to as insulating... the impeller has a surface resistance R O of at least 10 9Ω
Implementation Method 2
the at least one shaft bearing and/or the motor shaft and/or the shaft seal can also be designed to be insulated, in order to minimize discharges of charges via the shaft bearing
Data Source
Figure 1
AI summary
The invention relates to a fan comprising a housing and a fan wheel arranged on a motor shaft and being drivable by a motor. According to the invention, the fan is designed as a mixing fan for transporting and mixing a combustible medium with air, wherein at least the fan wheel is designed in an insulating manner.