Hydraulic Implement Attachment Locking Against Leak-Induced Cylinder Creep

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Solution Overview

Problem

Existing implement attachment systems for working machines, such as wheel loaders, face safety issues due to potential hydraulic leaks and pressure build-ups that can cause the attachment to become loose, compromising the secure attachment of implements.

Innovation Solution

A hydraulic attachment device with a conduit and valve arrangement that selectively allows communication between the piston side chamber and the rod side chamber of the hydraulic cylinder, ensuring equal pressures and preventing piston movement, even in case of leaks, using a locking valve that can be actuated electrically, hydraulically, or manually, and a method for refreshing hydraulic fluid to maintain system integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a 6/2-way valve is used to control hydraulic pressure for locking the implement attachment, then the attachment can be securely locked, but hydraulic leaks in the valve can cause pressure build-up that keeps the check valve open and causes the hydraulic cylinder to creep

Engineering Contradiction:
Improveattachment securityVSAvoidhydraulic leak effects
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the harmful function of the 6/2-way valve by removing it from the system and replacing it with a 2/2-way locking valve that only performs the locking function without the complex internal leakage paths. This separates the locking function from the control function, eliminating the source of pressure build-up that caused check valve malfunction.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces a check valve as an intermediary component that mediates between the hydraulic cylinder and the external environment. This check valve acts as a safety barrier that prevents external contamination and pressure anomalies from affecting the locking mechanism, while allowing normal hydraulic operation.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If hydraulic fluid is continuously circulated through the hydraulic cylinder to maintain pressure, then the attachment remains secure, but the hydraulic system accumulates contaminants and degrades over time

Engineering Contradiction:
Improveattachment securityVSAvoidhydraulic fluid quality
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

The patent implements periodic action by enabling the hydraulic system to alternate between two modes: normal operation mode where fluid circulates to maintain pressure, and refresh mode where the conduit and valve arrangement is reconfigured to allow fluid replacement. This periodic switching maintains both attachment security and fluid quality.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent applies discarding and recovering by enabling the system to discard degraded hydraulic fluid and recover fresh fluid through the reconfigurable conduit arrangement. The system can drain contaminated fluid from the cylinder and refill it with clean fluid, extending the service life of the hydraulic system while maintaining operational reliability.

Inventive Principle:
Principle #34Discarding and recovering

3Reliability

If the conduit and valve arrangement is configured to allow communication between piston side chamber and rod side chamber, then equal pressures are maintained and piston movement is prevented, but the system complexity increases

Engineering Contradiction:
Improveattachment securityVSAvoidconduit and valve arrangement
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies universality by designing a multi-functional conduit and valve arrangement that can serve multiple purposes: maintaining pressure equilibrium between chambers during normal operation, enabling fluid refreshment by reconfiguring the flow paths, and providing a controlled method for releasing locked position. This single integrated system replaces what would otherwise require multiple separate components.

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

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

The solution provides a robust and safe attachment mechanism that maintains the implement securely attached to the working machine, even in the event of pressure loss, and ensures the hydraulic system is refreshed with filtered fluid, enhancing safety and reliability.

Implementation Method 1

the communication between the piston side chamber and the rod side chamber will create equal pressures on either side of the piston

Methodology Applied
Scientific EffectHydraulic pressure transmission: Pascal's Law

Data Source

PatentEP3721020B1An implement attachment device
Publication Date: 2022.11.23 VOLVO CONSTRUCTION EQUIPMENT AB
  • EP3721020B1 patent drawingFigure 1
  • EP3721020B1 patent drawingFigure 2~3
  • EP3721020B1 patent drawingFigure 4~5

AI summary

The invention provides an implement attachment device (1000), for selectively attaching an implement to a working machine, comprising - a hydraulic cylinder (1100) comprising a cylinder housing with first and second longitudinal ends, a piston (1110) in the cylinder housing, and a piston rod (1111) fixed to the piston and protruding through the first end of the cylinder housing, - an attachment element (1115) being connected to a protruding portion of the piston rod, and adapted to engage with a complementary element of the implement, - a hydraulic conduit and valve arrangement (1201-1204) connected to the hydraulic cylinder (1100), - wherein the conduit and valve arrangement (1201-1204) is arranged to selectively allow a communication between a piston side chamber (1120) of the hydraulic cylinder (1100) and a rod side chamber (1121) of the hydraulic cylinder (1100).