Pump Control Method for Automatic Alternation

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Solution Overview

Problem

Existing pump control methods require communication between pumps or knowledge of the number of pumps, leading to wear issues and grease/dirt buildup in wastewater applications, especially when alternating between primary and secondary pumps.

Innovation Solution

Randomly changing the start condition of each pump within predetermined limits, including the pump start liquid level and time delay, to facilitate automatic alternation without direct or indirect communication between pumps, using dynamic level instruments to determine the liquid level.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a fixed pump start liquid level is used for all pumps, then the control system is simple, but a tidal mark of grease and dirt builds up at the fixed level which is harmful

Engineering Contradiction:
Improvecontrol system complexityVSAvoidgrease and dirt buildup
Core Design Contradiction:
Device complexityVSObject-affected harmful factors

Solution Approach 1:

The patent applies dynamics by making the pump start liquid level variable rather than fixed. Each pump is randomly assigned a start level within a predetermined range, and this assignment changes over time. This dynamic adjustment prevents the consistent buildup of grease and dirt at a single fixed level while maintaining relatively simple control logic.

Inventive Principle:
Principle #15Dynamics

2Reliability

If pumps alternate activation every second time or equally long periods, then pump wear is reduced, but the control unit needs knowledge about the number of pumps which increases system complexity

Engineering Contradiction:
Improvepump wear distributionVSAvoidcontrol system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements self-service by enabling each pump to independently determine its own activation timing based on its randomly assigned start level. The pumps automatically alternate activation without requiring the control unit to know the total number of pumps or to implement complex alternation scheduling. Each pump essentially serves itself by comparing its assigned level with the actual liquid level.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent applies parameter changes by varying the pump start liquid level parameter randomly within a predetermined range for each pump. This parameter variation ensures different pumps activate at different levels, distributing wear over time without requiring complex control logic to manage alternation schedules.

Inventive Principle:
Principle #35Parameter changes

3Device complexity

If the primary pump is used exclusively in normal pumping, then the control system is simple, but the primary pump experiences large wear and the secondary pump may fail when needed

Engineering Contradiction:
Improvecontrol system complexityVSAvoidpump wear and availability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent applies parameter changes by randomly assigning different start liquid level parameters to the primary and secondary pumps. This causes the pumps to alternate activation automatically based on liquid level fluctuations, distributing wear between both pumps while maintaining simple control logic. The primary pump is no longer exclusively used, and the secondary pump becomes reliably available when needed.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2721302B1Method for automatic mutual alternation between an arbitrary number of pumps
Publication Date: 2018.11.21 XYLEM IP HOLDINGS LLC
  • EP2721302B1 patent drawingFigure 1
  • EP2721302B1 patent drawingFigure 2
  • EP2721302B1 patent drawingFigure 3

AI summary

The invention relates to a method for automatic mutual alternation between an arbitrary number of pumps by the control of an individual pump, which makes use of a start condition for a state change from an inactive state of the pump into an active state of the pump to be performed, as well as makes use of a stop condition for a state change from said active state into said inactive state to be performed. According to the invention, the method comprises a sub method (Find start condition) that comprises the step of, after a predetermined stage, arbitrarily changing the start condition of the individual pump within predetermined limits.