Pump Cutting Impeller Axial Counter Knife

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Solution Overview

Problem

Centrifugal pumps used in machine tools to convey lubricating coolant emulsions contaminated with metal chips face challenges in effectively chopping fibrous materials like long metal chips and filaments, which tend to wind up on the shaft and cause contamination, leading to reduced robustness and efficiency.

Innovation Solution

The counter knives are designed with cutting edges extending along the shaft's longitudinal direction, combined with a toothed cutting edge configuration, to effectively chop fibrous materials through a scissor-like action with the cutting impeller, preventing them from settling on the shaft and enhancing robustness in contaminated media.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional counter knives without axial cutting edges are used, then the pump structure is simpler, but fibrous materials wind up on the shaft causing contamination and reduced robustness

Engineering Contradiction:

Improverobustness in contaminated mediaVSAvoidcounter knife structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The counter knife is segmented into multiple functional zones: a cutting edge extending axially along the shaft portion, a body portion, and optionally a sleeve structure. This segmentation allows the cutting edge to specifically address fibrous material chopping while the rest of the structure maintains structural support, resolving the contradiction between enhanced reliability and device complexity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The cutting edge on the counter knife performs preliminary chopping action on fibrous materials before they can wind up on the shaft. By pre-cutting the fibers in the intake region, the system prevents contamination and shaft wrapping, improving reliability without requiring complex additional components downstream.

Inventive Principle:

Principle #10Preliminary action

2Object-generated harmful factors

If counter knives with axial cutting edges are added, then fibrous materials are effectively chopped, but the device complexity increases

Engineering Contradiction:

Improvefiber winding on shaftVSAvoidcounter knife design

Core Design Contradiction:

Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The counter knife is designed to perform multiple functions: it provides structural support as a stationary component, creates scissor-like cutting action with the rotating cutting impeller, and the axial cutting edge specifically addresses fiber chopping. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity while effectively addressing fiber winding problems.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Productivity

If toothed cutting edges are used, then fibrous material is better gripped and chopped, but manufacturing complexity increases

Engineering Contradiction:

Improvechopping effectivenessVSAvoidtoothed cutting edge fabrication

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

The toothed structure is applied locally only to the cutting edges of the cutting impeller and counter knife, rather than the entire component. This localized application enhances chopping effectiveness where needed while keeping the rest of the components simple and easy to manufacture, thus resolving the contradiction between productivity and ease of manufacture.

Inventive Principle:

Principle #3Local quality

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 design ensures that fibrous materials are cut and prevented from winding up on the shaft, maintaining pump stability and efficiency even in strongly contaminated conditions by utilizing the swirling motion and suction forces to engage and chop fibers effectively.

Implementation Method 1

Due to the swirling motion of the medium flowing into the intake tube, which swirling motion is induced by the pre-chopper, and due to the suction of the axial impeller and the scissor action of the cutting impeller and the counter knives, the fibers are subject to such forces

Methodology Applied

Scientific EffectCentrifugal force: Centrifugal Force

Implementation Method 2

due to the suction of the axial impeller and the scissor action of the cutting impeller and the counter knives, the fibers are subject to such forces

Methodology Applied

Scientific EffectSuction: Suction

Implementation Method 3

the fibers are firmly dragged against the cutting edge and are then cut by the cutting edge

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 4

the scissor action of the cutting impeller and the counter knives, the fibers are subject to such forces

Methodology Applied

Scientific EffectMechanical force: Mechanical Force

Data Source

PatentUS7811051B2Pump with cutting impeller and pre-chopper

Publication Date: 2010.10.12 BRINKMANN PUMPEN K H BRINKMANN GMBH & CO KG

AI summary

Pump having a cutting impeller (38), counter knives (40) associated therewith, and a pre-chopper (48) which is driven by a shaft portion (46) that projects axially from the cutting impeller (38), characterised in that the counter knives (40) carry a cutting edge (52) that extends in longitudinal direction of the shaft portion (46).