Drive Shaft Eccentric Connection for Reciprocating Pump Assembly

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Solution Overview

Problem

Conventional drive units for high-pressure reciprocating pumps, especially those handling cryogenic liquids, face labor-intensive and time-consuming assembly and disassembly processes due to complex torque transmission connections, which are prone to wear and require precise sequences.

Innovation Solution

A method involving a non-positive connection between the drive shaft and eccentric parts using clamped wedge ring sleeves and rings, allowing easy assembly and disassembly by pushing components onto a straight drive shaft, with eccentric bearing parts designed for reliable frictional engagement and simplified bearing arrangements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If form-fitting connections with wedges are used to ensure non-rotatable connection between eccentric parts and drive shaft, then torque transmission reliability is improved, but assembly and disassembly complexity increases

Engineering Contradiction:
Improvetorque transmission reliabilityVSAvoidassembly complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The connection system is divided into separate components: the eccentric part with integrated bearing surfaces and the drive shaft with corresponding mating surfaces. This segmentation allows for simplified assembly where the eccentric part is pushed onto the drive shaft and secured with a retaining ring, eliminating the need for complex wedge assemblies while maintaining torque transmission reliability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The wedge connection mechanism is extracted and replaced with a direct friction fit combined with a retaining ring. The eccentric part is designed with bearing surfaces that directly contact the drive shaft, removing the intermediate wedge element that caused assembly complexity while maintaining the non-rotatable connection requirement.

Inventive Principle:
Principle #2Taking out (Extraction)

2Reliability

If press and shrink fits or welds are used for non-rotatable connections, then connection reliability is improved, but reversibility and assembly flexibility deteriorate

Engineering Contradiction:
Improveconnection reliabilityVSAvoidassembly flexibility
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The connection transitions from static permanent connections (welds, shrink fits) to a dynamic friction-based connection that can be easily assembled and disassembled. The eccentric part is pushed onto the drive shaft to create frictional engagement for non-rotatable connection, then secured with a retaining ring that can be removed to release the connection, providing both reliability and flexibility.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

A retaining ring serves as an intermediary element that secures the eccentric part to the drive shaft without creating permanent attachment. The retaining ring prevents rotation and allows easy removal, mediating between the need for reliable torque transmission and the need for assembly flexibility.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If multiple individual steps with precise sequences are required for assembly, then connection reliability is improved, but assembly time and labor requirements increase

Engineering Contradiction:
Improveconnection reliabilityVSAvoidassembly time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The eccentric part is pre-designed with integrated bearing surfaces and the drive shaft with corresponding mating surfaces, so that when assembled, the non-rotatable connection is automatically established through friction fit without requiring multiple individual steps or precise sequencing of separate components.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

Multiple connection functions (torque transmission, non-rotatable constraint, and retention) are merged into a single assembly operation where the eccentric part is pushed onto the drive shaft and secured with a retaining ring, eliminating the need for multiple separate steps and precise sequences.

Inventive Principle:
Principle #5Merging (Combining)

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 method simplifies the assembly and disassembly of piston housings in series, ensuring reliable torque transmission while reducing wear and labor requirements, and is scalable for multiple piston housings.

Implementation Method 1

the eccentric bearing parts can be clamped on the drive shaft with a wedge ring sleeve that can be placed on the eccentric bearing parts and a wedge ring that can be placed on the eccentric bearing parts and the wedge ring sleeves in order to produce the non-positive connection

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP2397694B1Method for assembling a drive unit for a reciprocating pump
Publication Date: 2015.08.05 FIVES CRYOMEC AG
  • EP2397694B1 patent drawingFigure 1
  • EP2397694B1 patent drawingFigure 2~3

AI summary

The drive unit has a reciprocating piston (3) with one or more piston housing (2), which are fixed together to a drive shaft (1), where the piston housing is actuated by a connecting rod (4). The connecting rods are supported to eccentric portion of the drive shaft, where the eccentric portions are designed with the drive shaft for a force-fit connection created during an assembled state.