Motor-Driven Chimney Draft Impeller Thermal Isolation
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Solution Overview
Problem
Existing motor-driven chimney draft systems face challenges in reducing heat transfer from hot flue gases to the motor, leading to increased costs due to the need for heat-resistant components.
Innovation Solution
The design incorporates an impeller with intermediate members that create a long, narrow heat transmission path between the flue gas deflector disk and the motor shaft, and includes impeller blades that draw fresh air for active cooling, forming a turbine wheel to separate cooling air from flue gases and provide insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the motor shaft directly contacts the flue gas deflector disk, then the structure is simple, but heat is conducted from the flue gases to the motor through the shaft
Solution Approach 1:
The patent introduces intermediate members (impeller blades) between the motor shaft and the flue gas deflector disk. These blades are connected to both components but create a long, narrow heat transmission path with high thermal resistance, effectively isolating the motor from heat while maintaining mechanical connection for power transmission.
2Reliability
If heat-resistant components are used in the motor, then the motor can operate at elevated temperatures, but the cost increases
Solution Approach 1:
The intermediate members create a thermal barrier that allows the motor to operate at lower temperatures without requiring expensive heat-resistant components, thereby reducing manufacturing costs while maintaining reliability.
3Reliability
If the flue gas deflector disk is made large, then cooling air is better separated from flue gases, but the device size increases
Solution Approach 1:
The patent uses the turbine wheel formed by impeller blades to actively draw cooling air through the venting holes and force it radially outward, creating an insulating air layer that separates cooling air from flue gases without requiring excessive disk size.
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
This solution significantly reduces heat transfer to the motor, allowing for cost-effective construction by preventing direct contact between the motor shaft and hot flue gases, while also providing active cooling and improved insulation.
Implementation Method 1
the impeller blades will force the air out in a radial direction and thereby provide cooling of the flue gas deflector disk and other components in contact with the air
Implementation Method 2
the transmission path for heat from the flue gases to the driving shaft of the motor can be made long and with a relatively small cross section, i.e. the path is narrow, which significantly increases the thermal resistance of the path
Implementation Method 3
The flue gas deflector disk keeps the flue gases separated from the air that is drawn in as cooling air
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
Impeller for a motor-driven chimney draft system, comprising a flue gas impeller (10) for creating, in a flue gas passage, a draft in a flue gas downstream direction. A flue gas deflector disk (20) is situated downstream relative to the flue gas impeller (10) and connected to the flue gas impeller (10); and a hub for connecting the impeller to an end portion of a driving shaft of a motor (100), wherein the hub and the end portion of the driving shaft, when connected, are both situated downstream relative to the flue gas deflector disk (20), the hub indirectly connected to the flue gas deflector disk (20) by means of intermediate members. Advantageously the intermediate members are impeller blades (40) connected to the downstream side of the flue gas deflector disk (20) and to a venting disk (30) with venting holes (31, 32) so as to form a turbine.