Draft inducer for low power multistage furnaces utilizing an electronically commutated motor system and an associated method of use
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Solution Overview
Problem
Existing furnace assemblies with draft inducers lack efficient torque and rotational speed control, leading to inefficient operation and potential condensate formation, which affects performance and reliability.
Innovation Solution
A permanent magnet electrically commutated motor with a controller that selectively operates in specific torque and rotational speed ranges, coupled with a motor cooling fan and draft inducer blower fan, to manage torque and speed during normal and transitional periods, preventing operation at intermediate ranges and thus minimizing condensate formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the motor operates continuously across all torque and speed ranges, then the motor provides flexible operation for various furnace conditions, but condensate formation occurs and operational efficiency decreases
Solution Approach 1:
The motor controller dynamically adjusts the motor's torque and rotational speed to operate only within predefined acceptable ranges, transitioning between discrete operational states rather than allowing continuous operation across all possible values. This dynamic range limitation prevents condensate formation while maintaining adaptability to different furnace conditions.
Solution Approach 2:
The system changes the operational parameters (torque and rotational speed) of the motor by establishing discrete acceptable ranges and using a controller to maintain operation within these ranges. The controller modifies motor operation to stay within predefined torque range 1-2 and rotational speed range 1-2, preventing harmful intermediate states that cause condensate formation.
2Ease of operation
If the motor operates at intermediate torque and speed ranges, then the motor provides smooth transitions between operational states, but operational efficiency decreases and condensate formation increases
Solution Approach 1:
The controller manages transitions between discrete torque and speed ranges dynamically, allowing smooth operational state changes while preventing sustained operation in inefficient intermediate ranges. The system transitions quickly through unacceptable ranges during state changes but maintains operation within acceptable ranges during normal operation.
3Device complexity
If the motor uses conventional commutation and control systems, then the system structure is simple, but torque and speed control precision is insufficient leading to condensate formation
Solution Approach 1:
The patent replaces conventional mechanical commutation systems with an electronically commutated motor system that uses electronic controllers to precisely regulate torque and rotational speed. This substitution enables accurate maintenance of operational parameters within predefined ranges, preventing condensate formation while managing system complexity through electronic control.
4Adaptability or versatility
If the motor operates without defined torque and speed ranges, then the motor provides unrestricted operation for all furnace conditions, but condensate formation occurs and reliability decreases
Solution Approach 1:
The system implements defined torque and rotational speed ranges as operational constraints, using the controller to maintain motor operation within these parameter boundaries. The controller monitors and adjusts motor operation to stay within acceptable ranges, ensuring reliable furnace operation while preventing condensate formation through precise parameter management.
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 enhances the operational efficiency and reliability of the furnace assembly by maintaining the motor within defined torque and speed ranges, reducing condensate formation and ensuring high burn efficiency, while allowing transitions for optimal performance.
Implementation Method 1
The motor cooling fan is configured and positioned to move air in a manner to cool at least some components of the motor
Implementation Method 2
a permanent magnet electrically commutated motor... The motor comprises a stator, a rotor
Data Source
AI summary
A furnace assembly comprising a non-condensing furnace with a draft inducer. The draft inducer includes a permanent magnet electrically commutated motor and a draft inducer blower fan. The motor includes a stator, a rotor, a motor cooling fan, and a controller. The rotor being rotatable relative to the stator, the fan being operatively coupled to the rotor such that rotation of the rotor causes rotation of the fan, the controller being configured to selectively operate the motor in first and second different torque ranges of the rotor, with the first and second torque range operating within a fixed percentage and within a fixed percentage of each other. The controller being configured such during normal operation, the motor is not operable at any torques between the first torque range and the second torque range except during transitionary periods.