Spool Valve Pressure Relief for Hydraulic Worktool Disconnect

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Solution Overview

Problem

Existing hydraulic systems for work machines face difficulties in disconnecting and reconnecting worktools under high pressure, making the process challenging and potentially unsafe.

Innovation Solution

A controller is introduced to perform a worktool disconnect routine, which reduces pressure in the hydraulic lines by instructing the spool valve to connect the worktool ports to a low-pressure tank line and a high-pressure flow source, allowing for controlled pressure reduction without additional valves or components, enabling safe and easy disconnection and connection of worktools.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the hydraulic system operates under high pressure to provide sufficient power for worktools, then the power and force output are improved, but the difficulty and safety risk of disconnecting worktools increases

Engineering Contradiction:
Improvehydraulic power outputVSAvoidworktool disconnection ease
Core Design Contradiction:
PowerVSEase of operation

Solution Approach 1:

The system automatically reduces hydraulic pressure in the lines before the worktool disconnection operation is attempted. The controller detects when a worktool is disconnected and activates the spool valve to redirect hydraulic fluid from the high-pressure worktool lines to the low-pressure tank line, reducing pressure before the operator needs to disconnect the quick-connect coupling.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The hydraulic system performs its own pressure reduction function using existing components (spool valve, tank line) that are already part of the normal hydraulic circuit. No external pressure relief device or additional valve is required - the system uses its own resources to solve the disconnection problem.

Inventive Principle:
Principle #25Self-service

2Ease of operation

If additional pressure relief valves or auxiliary components are added to reduce pressure for disconnection, then the ease of operation for disconnecting worktools is improved, but the device complexity increases

Engineering Contradiction:
Improveworktool disconnection easeVSAvoidhydraulic system complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The spool valve serves dual functions: it controls hydraulic fluid flow during normal worktool operation and automatically redirects flow to reduce pressure during disconnection. The tank line, normally used for return flow, is utilized as a pressure relief path. This multi-functionality eliminates the need for dedicated pressure relief components.

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

Solution Approach 2:

The pressure reduction function is merged with the existing hydraulic control circuit. The spool valve integrates the pressure relief function into its normal flow control operation, and the tank line serves both as a return line and a pressure relief path, combining multiple functions into existing components.

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

The controller effectively reduces pressure in the hydraulic lines, facilitating safe and efficient disconnection and reconnection of worktools, improving operational safety and reducing the risk of damage to connectors.

Implementation Method 1

instruct the spool valve to move to a first position wherein the first worktool port is connected to the low pressure tank line and the second worktool port is connected to the high pressure flow source

Methodology Applied
Scientific EffectHydraulic fluid flow redirection: Hydraulic Press

Data Source

PatentEP4226052B1Automatic pressure release
Publication Date: 2024.11.13 CATERPILLAR WORK TOOLS
  • EP4226052B1 patent drawingFigure 1
  • EP4226052B1 patent drawingFigure 2
  • EP4226052B1 patent drawingFigure 3

AI summary

A controller for hydraulic system of a work machine is provided. The controller is configured to perform a worktool disconnect routine to reduce pressure in a first worktool line and a second worktool line of the hydraulic system. The hydraulic system comprises a spool valve, a first worktool port connected to the spool valve by the first worktool line, a second worktool port connected to the spool valve by the second worktool line, a high pressure flow source of hydraulic fluid connected to the spool valve by a high pressure line and a low pressure tank line connected to the spool valve, the low pressure tank line at a lower pressure than a pressure of the high pressure line. When performing the worktool disconnect routine the controller is configured to: check that a power source of the work machine is operating, instruct the high pressure flow source of hydraulic fluid to provide no flow of hydraulic fluid in the high pressure line to the spool valve, instruct the spool valve to move to a first position wherein the first worktool port is connected to the low pressure tank line and the second worktool port is connected to the high pressure flow source in order to reduce a pressure in the first worktool line, and instruct the spool valve to move to a second position wherein the second worktool port is connected to the low pressure tank line and the first worktool port is connected to the high pressure flow source in order to reduce a pressure in the second worktool line.