Pump Blade Length and Thrust Bearing Friction

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Solution Overview

Problem

Conventional pumps in heat pump apparatuses face issues with reduced liquid pumping capacity due to shortened blade length, increased friction loss and wear from thrust force, and backflow, resulting in low efficiency and short longevity.

Innovation Solution

The pump design extends the effective length of blades toward the suction inlet's inside radius, reduces friction loss by minimizing pressure differences between blade plates, and prevents backflow through a bearing configuration with flow paths that guide liquid perpendicular to the shaft, enhancing sealing and thrust bearing performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If the shaft support portion is fitted into the suction opening to hold the shaft and thrust washer, then the shaft position is stabilized, but the effective length of the blades is shortened reducing liquid pumping capacity

Engineering Contradiction:
Improveeffective length of bladesVSAvoidliquid pumping capacity
Core Design Contradiction:
Length of moving objectVSProductivity

Solution Approach 1:

The invention extracts the shaft support function from the suction opening area by providing a separate shaft support portion that does not encroach on the blade effective length. The shaft support portion is positioned such that it holds the shaft and thrust washer without reducing the blade length, thereby separating the support function from the flow path obstruction that previously shortened the blades.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention resolves the spatial conflict by repositioning the shaft support portion in a different dimensional arrangement. Instead of the shaft support portion being fitted into the suction opening (which reduced blade length), the support portion is positioned adjacent to or integrated with the impeller in a manner that provides shaft support without intruding into the radial space required for blade operation.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Device complexity

If the suction opening has approximately the same radius as the suction inlet, then the shaft support structure is simplified, but thrust force increases friction loss and wear of the thrust bearing

Engineering Contradiction:
Improveshaft support structureVSAvoidfriction loss of thrust bearing
Core Design Contradiction:
Device complexityVSLoss of energy

Solution Approach 1:

The invention changes the dimensional parameters of the suction opening relative to the suction inlet. By making the suction opening radius smaller than the suction inlet radius, the patent creates a radial gap that reduces the pressure difference across the thrust bearing, thereby reducing thrust force and friction loss while maintaining structural simplicity.

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If there is a gap between the upper blade plate and the upper casing, then assembly is easier, but liquid backflows to the suction inlet reducing pump efficiency

Engineering Contradiction:
Improveassembly easeVSAvoidpump efficiency
Core Design Contradiction:
Ease of manufactureVSProductivity

Solution Approach 1:

The invention introduces a seal member as an intermediary element between the upper blade plate and the upper casing. This seal member fills the gap that would otherwise allow backflow, preventing liquid from leaking from the discharge side back to the suction inlet, while still allowing for practical assembly and disassembly of the pump components.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 configuration improves the pump's efficiency and longevity by increasing liquid pumping capacity, reducing friction loss, and preventing backflow, leading to a highly efficient and long-lasting pump and heat pump apparatus.

Implementation Method 1

a bearing (18-1) which receives the shaft (27), wherein the bearing (18-1) has a guide portion for guiding the liquid drawn in through the suction inlet (22) to the discharge outlet (23)

Methodology Applied
Scientific EffectFluid flow guidance:

Implementation Method 2

Rotation of the impeller 25 produces centrifugal force which acts on a liquid and causes the liquid to be pumped from a suction inlet 22 to a discharge outlet 23

Methodology Applied
Scientific EffectCentrifugal force: Centrifugal Force

Data Source

PatentEP2397697B1Pump and heat pump apparatus
Publication Date: 2019.09.04 MITSUBISHI ELECTRIC CORP
  • EP2397697B1 patent drawingFigure 1
  • EP2397697B1 patent drawingFigure 2
  • EP2397697B1 patent drawingFigure 3(a)~3(b)

AI summary

A highly efficient and long-life pump is provided through improvement of pump efficiency by extending an effective length of a blade of an impeller and through reduction of friction loss of a thrust bearing. In a pump (110), a suction direction (X) and a discharge direction (Y) of a liquid are approximately perpendicular to each other. The pump (110) includes a shaft (27) positioned downstream of a suction inlet (22); an impeller (25) configured in a disk shape that rotates around the shaft (27), the impeller (25) having a plurality of blades (25c) formed radially in a radial direction from a center area located at a center portion of the disk shape as seen in the suction direction (X), the plurality of blades (25c) being positioned at an approximately same longitudinal position as a longitudinal position of a discharge outlet (23); and a bearing (18-1) that receives the shaft (27), the bearing (18-1) being positioned at the center area of the impeller (25) and having a through hole (18-1c) as a guide portion for guiding the liquid drawn in from the suction inlet (22) to the discharge outlet (23).