Pump Rod and Drive Link Geometry for Reduced Side Loading

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Solution Overview

Problem

Axial displacement pumps in fluid dispensing systems face challenges with the time-intensive process of attaching and detaching the pump rod from the reciprocating drive, and experience wear due to non-coincident driving forces, leading to reduced efficiency and lifespan.

Innovation Solution

The system incorporates a clamp with an axial ring and a tightening ring that secures the displacement pump to the drive housing, using a clamping mechanism to align and stabilize the pump rod, reducing misalignment and wear by concentrating forces along the centerline through a load concentrating feature.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the pump rod is pinned to the reciprocating drive using a pin, then the connection is secure, but the attachment and detachment process becomes time-intensive and requires loose parts and tools

Engineering Contradiction:
Improveconnection securityVSAvoidattachment and detachment time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The connection mechanism is divided into modular components: a pump rod with a head portion and a drive link with a drive cavity. This segmentation allows the components to be easily assembled and disassembled without requiring multiple loose parts and tools, resolving the contradiction between secure connection and quick attachment/detachment.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The drive cavity acts as an intermediary structure that receives and secures the pump rod head. This intermediary mechanism provides a secure connection while enabling quick attachment and detachment, eliminating the need for time-consuming pinning operations.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If the pump rod is pinned to the reciprocating drive, then the connection is secure, but the process requires loose parts and several tools

Engineering Contradiction:
Improveconnection securityVSAvoidnumber of parts and tools
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The pump rod head and drive cavity are designed to work together as an integrated connection system. The drive cavity incorporates securing features directly into its structure, merging the functions of connection and securing into a single mechanism, thereby eliminating the need for separate pins and multiple tools.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The drive cavity serves as an intermediary structure that provides both the connection interface and the securing mechanism in one component, reducing the overall number of parts and tools required for assembly and disassembly while maintaining connection security.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Ease of operation

If the pump rod experiences driving forces not coincident with its centerline, then the pump can be driven, but the pump rod experiences wear on various components

Engineering Contradiction:
Improvedriving capabilityVSAvoidcomponent wear
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The drive cavity is designed with a specific local geometry that ensures the driving force is applied at a precise location on the pump rod head. This local quality control ensures that the force vector passes through or near the centerline of the pump rod, minimizing side loads and reducing component wear while maintaining driving capability.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The drive cavity acts as an intermediary that mediates the transmission of driving force to the pump rod. By designing the drive cavity with appropriate geometric features, it ensures that the force is transmitted along the centerline of the pump rod, preventing misalignment and reducing wear on the pump rod and associated components.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP3240955B1Pump rod and driving link with side-load reducing configuration
Publication Date: 2023.06.28 GRACO MINNESTOA INC
  • EP3240955B1 patent drawingFigure 1
  • EP3240955B1 patent drawingFigure 2
  • EP3240955B1 patent drawingFigure 2A

AI summary

A pump rod has a head extending from a neck, and the head is received within a drive slot of a drive link. The head includes a projection, and has an area smaller than an area of the head. The projection contacts an inner surface of the drive slot. The drive link may include a projection aligned with a centerline of the drive link. The drive link projection contacts a head of the pump rod. The projections provide a reduced contact area between the pump rod and the drive link, thereby reducing any side-loading on the pump rod and increasing a lifespan of the wear parts.