Centrifugal Fan Pre-Pressing Portion Axial Movement Restriction

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Solution Overview

Problem

Centrifugal fans face challenges in suppressing axial movement of the impeller, leading to friction with the housing and reduced service life, as existing solutions like magnetic devices require high magnetic force and are costly, or snap rings are not wear-resistant and mechanically weak.

Innovation Solution

A centrifugal fan design featuring a pre-pressing portion that expands radially inward from the air inlet edge, with obliquely positioned connection portions to restrict impeller movement and guide air flow, enhancing air suction efficiency without affecting motor efficiency or blade shape.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a magnetic device is used to suppress axial movement of the impeller, then the impeller axial movement is restricted, but the cost increases and implementation becomes difficult due to requiring large magnetic force

Engineering Contradiction:

Improveimpeller axial movement restrictionVSAvoidimplementation difficulty and cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces the magnetic device (electromagnetic field-based system) with a mechanical pre-pressing portion that directly contacts and presses the impeller axially. This mechanical substitution eliminates the need for complex magnetic actuators and large magnetic forces, significantly reducing cost and implementation difficulty while maintaining effective axial movement restriction.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The pre-pressing portion acts as a mechanical intermediary between the impeller housing and the impeller. It transmits the pressing force from the housing to the impeller surface, enabling effective axial restriction through simple mechanical contact rather than requiring complex magnetic field generation systems.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If a snap ring is disposed in the outer periphery of the rotation axis to suppress axial movement, then the impeller axial movement is restricted, but the service life is reduced due to wear and low mechanical strength

Engineering Contradiction:

Improveimpeller axial movement restrictionVSAvoidservice life

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent removes the snap ring component entirely from the system. Instead of using a snap ring that contacts the rotation axis periphery, the design extracts this function and implements axial restriction through the pre-pressing portion pressing the impeller surface directly, eliminating the wear and strength issues associated with snap rings.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The pre-pressing portion is made from wear-resistant material (such as engineering plastics or composite materials) that combines low friction properties with high mechanical strength. This material selection ensures long service life by resisting wear from continuous contact with the rotating impeller while maintaining sufficient pressing force.

Inventive Principle:

Principle #40Composite materials

3Reliability

If the rotation speed of the impeller is controlled to prevent axial movement, then the impeller axial movement is restricted, but the air suction efficiency cannot be improved

Engineering Contradiction:

Improveimpeller axial movement restrictionVSAvoidair suction efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent separates the functions of axial movement restriction and air suction optimization into independent components. The pre-pressing portion handles axial restriction mechanically, while the impeller blade design and rotation speed can be independently optimized for air suction efficiency without compromising axial stability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The pre-pressing portion provides dynamic axial restriction that adapts to operating conditions. It maintains sufficient pressing force to prevent axial movement during high-speed rotation while allowing the impeller to rotate freely without mechanical interference, enabling optimal rotation speeds for air suction efficiency.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS11486414B2Fan and electromechanical apparatus

Publication Date: 2022.11.01 NIDEC CORP(JP)

AI summary

A fan includes an impeller rotating on a central axis, an impeller housing, a motor located on one side in an axial direction of the impeller and driving the impeller to rotate, and a motor housing. The impeller housing is provided with an air inlet. The fan further includes a pre-pressing portion expanding radially inward from an edge of the air inlet. The pre-pressing portion includes a pressing portion located on another side in the axial direction of the impeller and pressing, from the another side in the axial direction, an end portion of the impeller on the another side in the axial direction, and at least two connection portions connected between an outer periphery of the pressing portion and the edge of the air inlet. The connection portions are disposed obliquely with respect to the axial direction.