Two-Cylinder Piston Pump Mode Switching via Internal Bridge Channels

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Solution Overview

Problem

Existing two-cylinder piston pumps face challenges with complex and impractical mode switching due to high pressure losses, sealing issues, and increased installation effort caused by numerous hydraulic connections, which complicates operation and safety in construction sites.

Innovation Solution

A hydraulically driven two-cylinder piston pump with a switching device that connects piston-side chambers directly to the switching device via passage channels, reducing the need for hydraulic oil lines and using adapter flanges and expansion sleeves for secure attachment, allowing for efficient mode switching without modifying the switching device for differential cylinders of varying diameters.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If numerous hydraulic lines and connection points are used for mode switching, then the pump can switch between piston-side and rod-side operation, but leakage problems occur and pressure losses increase

Engineering Contradiction:
Improvemode switching capabilityVSAvoidleakage resistance
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent integrates the switching device directly into the differential cylinder structure, merging the switching function with the existing hydraulic chambers. This eliminates the need for separate hydraulic lines and external connection points, thereby reducing leakage risks while maintaining mode switching capability between piston-side and rod-side operation

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent introduces a bridge oil line as an intermediary element that connects the rod-side chambers of both differential cylinders internally. This bridge oil line serves as a controlled intermediary pathway for hydraulic oil flow, enabling mode switching without requiring external hydraulic lines and multiple connection points that would increase leakage risk

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If numerous hydraulic lines and system components are used for mode switching, then the pump can switch between operating modes, but pressure losses increase

Engineering Contradiction:
Improvemode switching capabilityVSAvoidpressure loss
Core Design Contradiction:
Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The switching device is merged with the differential cylinder structure, eliminating multiple separate hydraulic lines and components. This integration reduces the number of connection points and flow path interruptions, thereby minimizing pressure losses during mode switching while maintaining the ability to switch between piston-side and rod-side operation

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The bridge oil line provides a continuous internal pathway for hydraulic oil flow between the rod-side chambers of both differential cylinders. This continuous flow path eliminates interruptions and pressure losses associated with external hydraulic lines, valves, and connection points, enabling smooth mode switching with minimal energy loss

Inventive Principle:
Principle #20Continuity of useful action

3Adaptability or versatility

If many hydraulic lines are required for mode switching, then the pump can switch between piston-side and rod-side operation, but assembly and cost effort increase

Engineering Contradiction:
Improvemode switching capabilityVSAvoidassembly effort
Core Design Contradiction:
Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The switching device is integrated directly into the differential cylinder structure, merging multiple functions into a single component assembly. This eliminates the need for assembling numerous separate hydraulic lines, connection points, and external switching components, thereby significantly reducing assembly effort and manufacturing complexity while maintaining mode switching capability

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The differential cylinder structure is designed to serve multiple functions: it acts as both the hydraulic actuator and the switching device housing. The bridge oil line simultaneously serves as both a hydraulic connection and a mode switching mechanism. This multi-functionality reduces the number of separate components that need to be manufactured and assembled, lowering overall assembly effort and cost

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

4Adaptability or versatility

If hydraulic hoses are extensively used for mode switching, then the pump can switch between operating modes, but the risk of leaks and damage increases

Engineering Contradiction:
Improvemode switching capabilityVSAvoidleak risk
Core Design Contradiction:
Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The switching device is merged with the differential cylinder structure, eliminating the need for extensive external hydraulic hoses and connection points. This integration reduces the exposed hydraulic components that are susceptible to leaks and damage, while maintaining the ability to switch between piston-side and rod-side operation through internal flow paths

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The bridge oil line serves as an internal intermediary pathway that eliminates the need for external hydraulic hoses connecting the rod-side chambers of both differential cylinders. This internal intermediary pathway is protected within the cylinder structure, reducing the risk of leaks and damage compared to extensive external hose connections

Inventive Principle:
Principle #24Intermediary (Mediator)

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 solution reduces the risk of damage and leaks, simplifies assembly, and ensures secure operation by minimizing hydraulic hose requirements and enhancing the mechanical strength of connections, enabling safe and efficient switching between piston and rod-side modes.

Implementation Method 1

the hydraulic oil for driving the differential cylinders 22, 23 of the two-cylinder piston pump 1 is directed to the drive piston 8 of a differential cylinder 22 via a control circuit (not shown)

Methodology Applied
Scientific EffectHydraulic pressure: Pressure Increase

Data Source

PatentEP3265680B1Two-cylinder piston pump
Publication Date: 2019.10.09 SCHWING GMBH
  • EP3265680B1 patent drawingFigure 1~2
  • EP3265680B1 patent drawingFigure 3~4
  • EP3265680B1 patent drawingFigure 5~6

AI summary

The invention relates to a hydraulically driven two-cylinder piston pump (1), comprising a first differential cylinder (22), which has a piston-side chamber (51) and a rod-side chamber (53) and drives a first conveying piston (4) by means of a first piston rod (6), a second differential cylinder (23), which has a piston-side chamber (52) and a rod-side chamber (54) and which drives a second conveying piston (5) by means of a second piston rod (7), and a switch-over device (14), which sets a piston- or rod-side operating mode of the two-cylinder piston pump (1) by switching over the flow of hydraulic fluid to the chambers (51, 52, 53, 54) of the differential cylinders (22, 23), wherein the switch-over device (14) is arranged on the bottoms (48, 49) of the piston-side chambers (51, 52) of the differential cylinders (22, 23) as a bridge-forming connection between the differential cylinders (22, 23). The invention is characterized in that the switch-over device (14) comprises passage channels (28, 29) for the hydraulic fluid for driving the differential cylinders (22, 23), by means of which passage channels the piston-side chambers (51, 52) of the differential cylinders (22, 23) are connected to the switch-over device (14) without hydraulic-fluid lines. The invention further relates to a method for operating a hydraulically driven two-cylinder piston pump according to the invention.