Rotary Pump Guard System for Safety and Inspection Access

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Solution Overview

Problem

Existing rotary positive displacement pumps face challenges in balancing health and safety regulations with hygiene requirements, as current guard designs are costly, complex, and often compromised for visibility and maintenance, leading to increased risks and inefficiencies.

Innovation Solution

The design incorporates a novel guard system that allows for improved visibility and accessibility to seal flushing connections and other features while maintaining safety, by positioning guards closer to the drive shafts and using a single guard to cover both drive shafts, reducing the need for multiple guard variants.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If guards are fitted to cover the complete area between rotor casing and transmission housing, then health and safety requirements are met, but visibility of drive shaft seal leakage is reduced and complete removal is required for inspection

Engineering Contradiction:
Improvehealth and safety protectionVSAvoidvisibility and inspection accessibility
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The guard is divided into a first guard portion and a second guard portion that can be independently removed. The first guard portion covers the drive shaft area for safety, while the second guard portion can be removed to provide visibility and access to seal flushing connections, eliminating the need to remove the entire guard for inspection

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The guard design allows dynamic configuration where the first and second guard portions can be selectively positioned and removed. This enables the guard to adapt between providing complete coverage for safety and providing partial exposure for inspection and maintenance activities

Inventive Principle:
Principle #15Dynamics

2Ease of operation

If guards are pre-cut to allow flush connections, then accessibility to seal flushing is improved, but health and safety requirements are compromised when unflushed seals are fitted

Engineering Contradiction:
Improveaccessibility to seal flushing connectionsVSAvoidhealth and safety protection
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The guard is segmented into first and second portions with different functions. The first guard portion maintains complete coverage for safety, while the second guard portion provides access to flush connections. This segmentation allows the pump to accommodate different seal types without compromising safety or accessibility

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The guard design accommodates different operational parameters by providing configurable access. When flushable seals are installed, the second guard portion can be positioned to allow flush media connection. When unflushed seals are used, the first guard portion maintains complete safety coverage without requiring pre-cuts

Inventive Principle:
Principle #35Parameter changes

3Adaptability or versatility

If multiple guard designs are created for different seal types and heating/cooling configurations, then specific requirements are met, but cost and complexity of designing, manufacturing, and spare part handling increase significantly

Engineering Contradiction:
Improvecompatibility with different seal types and configurationsVSAvoidnumber of guard variants
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The single guard design with first and second portions serves multiple functions across different pump configurations. The same guard structure can be used with flushable seals, unflushed seals, heating applications, and cooling applications by selectively positioning or removing the first and second guard portions, eliminating the need for multiple specialized guard designs

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The guard system provides dynamic adaptability through selective positioning of the first and second guard portions. This allows a single guard design to accommodate various operational requirements (different seal types, heating/cooling configurations) without requiring multiple static guard variants, thereby reducing manufacturing complexity and spare part inventory

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP4281670B1A rotary positive displacement pump with a guard
Publication Date: 2025.06.04 ALFA LAVAL CORP AB
  • EP4281670B1 patent drawingFigure 1~2
  • EP4281670B1 patent drawingFigure 3~5
  • EP4281670B1 patent drawingFigure 6

AI summary

A rotary positive displacement pump (1) for pumping a fluid product, wherein the pump (1) has a front side and a rear side. The pump comprises a transmission housing (2) having an axial front wall (38) and an axial rear wall and providing rotational support to first and second parallel and axially extending drive shafts (4, 5) having gears (6, 7) in constant mesh condition, such that the first and second drive shafts (4, 5) are arranged to rotate in opposite directions. The pump further comprises a rotor casing (15) connected to a front side (13) of the transmission housing (2) and having an axial rear wall (20), an axial front wall (22) and a circumferential side wall (21) jointly defining a stationary interior pumping cavity. The rotor casing (15) houses a first rotor (23) that is drivingly connected to the first drive shaft (4) and a second rotor (24) that is drivingly connected to the second drive shaft (5). The first and second rotors (23, 24) are configured for rotating in opposite directions and mutually interacting for providing a positive pumping effect on a fluid product that enters the pumping cavity via a rotor casing inlet (30) and exits the pumping cavity via a rotor casing outlet (31). Moreover, the axial front wall (38) of the transmission housing (2) and the axial rear wall (20) of the rotor casing jointly define an intermediate space (42) through which the first and second drive shafts (4, 5) extend. The rotary positive displacement pump (1) further comprises a first guard (51) located in said intermediate space (42) and surrounding the first and second drive shafts (4, 5) for protecting a person from contacting the first and second drive shafts (4, 5); or a first guard (51) located in said intermediate space (42) and surrounding the first drive shaft (4) for protecting a person from contacting the first drive shaft (4), and a second guard (52) located in said intermediate space (42) and surrounding the second drive shaft (5) for protecting a person from contacting the second drive shaft (5).