Drag Pump Channel Protrusions to Block Reverse Flow

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Solution Overview

Problem

Existing drag pumps face inefficiencies due to reverse transmission or backflow of fluids, particularly at the inlet end, which decreases performance and increases power consumption when attempting to increase channel length or reduce channel angle.

Innovation Solution

The introduction of protrusions at the inlet and outlet ends of drag pump channels to divide them into narrower sub-channels, reducing reverse flow without significantly affecting power consumption, while maintaining wider channels in the middle portion for efficient compression.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stress or pressure

If the length of the channels is increased to improve compression, then the compression ratio increases, but the pump size increases which is not desirable

Engineering Contradiction:
Improvecompression ratioVSAvoidpump size
Core Design Contradiction:
Stress or pressureVSVolume of moving object

Solution Approach 1:

The patent divides each channel into multiple sub-channels by introducing protrusions that extend from the rotor surface into the channel. This segmentation allows the channel to be effectively lengthened through multiple passes while maintaining a compact overall pump structure, resolving the contradiction between compression ratio and pump size.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces protrusions that extend into the channel from the rotor surface, adding a third dimension to the channel structure. This allows the channel to fold back on itself multiple times within the same axial space, effectively increasing the channel length without increasing the pump's external dimensions.

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

2Stress or pressure

If the channel angle is decreased to improve compression, then the compression ratio increases, but the opportunity for reverse transmission of molecules increases

Engineering Contradiction:
Improvecompression ratioVSAvoidreverse transmission of molecules
Core Design Contradiction:
Stress or pressureVSObject-generated harmful factors

Solution Approach 1:

By segmenting the channel into sub-channels with protrusions, the patent creates multiple barriers that molecules must pass through. This segmentation reduces the likelihood of reverse transmission while maintaining a steeper channel angle for improved compression.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The protrusions act as intermediary structures within the channel, creating additional wall surfaces that molecules must interact with. These intermediaries prevent direct reverse flow paths while allowing forward compression, resolving the contradiction between compression ratio and reverse transmission.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Object-generated harmful factors

If the channels are narrowed to decrease reverse transmission, then reverse flow is reduced, but the power consumption increases

Engineering Contradiction:
Improvereverse flowVSAvoidpower consumption
Core Design Contradiction:
Object-generated harmful factorsVSUse of energy by stationary object

Solution Approach 1:

The patent segments the channel into sub-channels using protrusions, which reduces reverse flow by creating multiple barriers without requiring a uniform narrowing of the entire channel. This localized segmentation reduces reverse flow while minimizing the impact on power consumption compared to narrowing the entire channel.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The protrusions are positioned at specific locations within the channel where reverse flow is most problematic. This local modification addresses the reverse flow issue at critical points without unnecessarily narrowing the channel throughout its entire length, thereby minimizing the increase in power consumption.

Inventive Principle:
Principle #3Local quality

4Productivity

If protrusions are added to narrow channels at the inlet end to reduce reverse flow, then pumping efficiency at the inlet improves, but power consumption increases

Engineering Contradiction:
Improvepumping efficiency at inletVSAvoidpower consumption
Core Design Contradiction:
ProductivityVSUse of energy by stationary object

Solution Approach 1:

The protrusions are strategically positioned at the inlet end of the channel where reverse flow is most problematic. This local modification improves pumping efficiency at the critical inlet region without unnecessarily narrowing the channel throughout its entire length, thereby minimizing the increase in power consumption.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent applies the narrowing effect partially, only at the inlet end of the channel where it is most needed, rather than throughout the entire channel length. This partial action provides sufficient improvement in pumping efficiency while limiting the increase in power consumption.

Inventive Principle:
Principle #16Partial or excessive action

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

Enhances pumping efficiency and reduces recirculation, maintaining capacity and compression within a compact design by effectively extending the effective channel length and blocking reverse flow.

Implementation Method 1

Drag pumps operate by adding momentum to molecules in a fluid within the pump in a direction from an inlet towards an outlet

Methodology Applied
Scientific EffectMomentum transfer: Conservation of Momentum

Implementation Method 2

Relative rotation of the two surfaces pushes gas molecules along the channels

Methodology Applied
Scientific EffectDrag: Drag

Implementation Method 3

The walls of the channels in such a drag pump direct the flow of the molecules, so that increasing the length of the channels increases the compression

Methodology Applied
Scientific EffectCompression: Compression

Implementation Method 4

The cross-over point between the ridges on rotation of the rotor runs in a conveying direction for the gas from an inlet at the centre of the disk to an outlet at the outer edge of the disk. This is so that the centrifugal force is in the direction of travel

Methodology Applied
Scientific EffectCentrifugal force: Centrifugal Force

Data Source

PatentEP4004377B1Molecular drag pump
Publication Date: 2026.03.25 EDWARDS LTD
  • EP4004377B1 patent drawingFigure 1~2
  • EP4004377B1 patent drawingFigure 3~4
  • EP4004377B1 patent drawingFigure 5~6

AI summary

A drag pump for pumping fluid from an inlet to an outlet is disclosed. The drag pump comprises a stator and a rotor. One of the stator or rotor comprises a disc comprising a plurality of channels each of the channels extending from an inlet portion of the disc at or close to an inlet edge towards an outlet portion at or close to an outlet edge. The plurality of channels each comprise walls for guiding fluid flow from the inlet edge to the outlet edge in response to relative motion between the stator and the rotor. The disc further comprises a plurality of protrusions extending from the channels, each of the protrusions being arranged to divide a channel at the inlet or the outlet end of the channel, into sub-channels that extend for a portion of a length of the channel and do not extend for a whole length of the channel.