HVAC Fan Bearing Assembly to Block Reverse Rotation

Solution Overview

Problem

In HVAC systems, the deactivation of condenser fans during low outdoor temperatures leads to backflow of air across inactive fans, causing reverse rotational motion, which reduces the effectiveness of operational fans, increases torque load, and can result in wear and performance degradation, as well as hinder the use of certain electric motors.

Innovation Solution

A unidirectional bearing assembly is integrated into the condenser fan system, allowing rotation in one direction while blocking rotation in the opposite direction, thereby preventing reverse rotational motion of inactive fans and maintaining them in a stationary position to reduce backflow and restart load.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If condenser fans are deactivated during low outdoor temperatures, then energy consumption is reduced, but backflow of air causes reverse rotational motion that reduces effectiveness of operational fans and increases torque load

Engineering Contradiction:

Improveenergy consumptionVSAvoideffectiveness of operational fans

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The bearing is segmented into asymmetric lobes with different clearance characteristics for different rotational directions, allowing selective restriction of reverse rotation while permitting forward rotation during normal operation

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The bearing introduces localized asymmetric clearance properties at specific locations (lobes) within the bearing structure, creating different friction characteristics for clockwise versus counter-clockwise rotation to prevent backflow-induced reverse rotation

Inventive Principle:

Principle #3Local quality

2Use of energy by moving object

If condenser fans are deactivated during low outdoor temperatures, then energy consumption is reduced, but reverse rotational motion increases torque load and causes wear

Engineering Contradiction:

Improveenergy consumptionVSAvoidtorque load and wear resistance

Core Design Contradiction:

Use of energy by moving objectVSStrength

Solution Approach 1:

The unidirectional bearing proactively prevents reverse rotational motion before it can occur by creating asymmetric friction resistance, thereby eliminating the harmful torque loads and wear that would otherwise result from backflow-induced reverse rotation

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The bearing introduces localized asymmetric clearance properties at specific locations (lobes) within the bearing structure, creating different friction characteristics for clockwise versus counter-clockwise rotation to prevent backflow-induced reverse rotation

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If conventional bearings are used, then manufacturing is simpler, but reverse rotation cannot be prevented and system performance deteriorates

Engineering Contradiction:

Improvebearing manufacturing complexityVSAvoidsystem operational efficiency

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The bearing introduces localized asymmetric clearance properties at specific locations (lobes) within the bearing structure, creating different friction characteristics for clockwise versus counter-clockwise rotation to prevent backflow-induced reverse rotation

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The bearing modifies the clearance parameter asymmetrically in different rotational directions, creating unidirectional friction characteristics that prevent reverse rotation while maintaining forward rotation capability

Inventive Principle:

Principle #35Parameter changes

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 of condenser fans by reducing backflow and restart load, allowing the use of less expensive single phase permanent split capacitor motors, and improving overall system performance by maintaining fan blades in a position to impede backflow air.

Implementation Method 1

a unidirectional bearing that is coupled to the shaft and a mounting assembly of the condenser fan assembly, where the unidirectional bearing is configured to block rotation of the shaft in a second direction that is opposite the first direction

Methodology Applied

Scientific EffectUnidirectional bearing mechanism:

Data Source

PatentUS11125275B2Bearing assembly for a fan of an HVAC system

Publication Date: 2021.09.21 JOHNSON CONTROLS LIGHT COMMERCIAL IP GMBH

AI summary

The present disclosure relates to a heating, ventilation, and/or air conditioning (HVAC) unit including a condenser coil and a condenser fan assembly. The condenser fan assembly includes a first fan and a second fan, where the first fan and the second fan are each configured to operate to pull air through the condenser coil. The HVAC unit also includes a motor of the first fan including a housing and a shaft, where the motor is configured to operate to rotate the shaft in a first direction. The HVAC unit further includes a unidirectional bearing that is coupled to the shaft and a mounting assembly of the condenser fan assembly, where the unidirectional bearing is configured to block rotation of the shaft in a second direction that is opposite the first direction.