Auxiliary Hydraulic Depressurization for Quick Tool Couplers

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Solution Overview

Problem

Existing hydraulic systems in work machines require manual connection and disconnection of hydraulic lines along with work tools, lacking an efficient method for depressurizing the auxiliary circuits during tool attachment and detachment.

Innovation Solution

A control system and method for automatically depressurizing the work tool auxiliary circuit using a controller to actuate relief valves based on target pressure or duration, facilitating the unlocking and locking of quick couplers through lock members, ensuring seamless hydraulic fluid management.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If manual connection and disconnection of hydraulic lines is used, then hydraulic fluid management is simple, but operational efficiency is reduced and manual effort is increased

Engineering Contradiction:
Improveoperational efficiencyVSAvoidmanual effort
Core Design Contradiction:
ProductivityVSEase of operation

Solution Approach 1:

The system automatically manages hydraulic fluid depression through relief valves and control systems without requiring manual intervention. The controller monitors pressure sensors and automatically opens relief valves to depressurize circuits when tools are detached, making the system self-servicing and eliminating manual hydraulic line management

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces manual mechanical operations with an automated control system that uses electronic sensors, controllers, and electronically controlled relief valves. The controller receives signals from pressure sensors and automatically actuates relief valves, substituting manual mechanical fluid management with an automated electromechanical system

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Stability of the object's composition

If hydraulic pressure is maintained in detached tools, then system pressure is stable, but tool drift or damage occurs due to thermal expansion

Engineering Contradiction:
Improvesystem pressure stabilityVSAvoidtool drift or damage
Core Design Contradiction:
Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The system performs preliminary depression of the hydraulic circuit before tool detachment by monitoring pressure sensors that detect when a tool is removed. The controller automatically opens relief valves to depressurize the circuit in advance, preventing thermal expansion damage and tool drift before they can occur

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system uses pressure sensors to continuously monitor hydraulic circuit pressure and provides feedback to the controller. When the controller detects pressure above a threshold or when a tool detachment signal is received, it automatically actuates relief valves to maintain pressure within safe limits, preventing tool damage from thermal expansion

Inventive Principle:
Principle #23Feedback

3Extent of automation

If automated relief valve actuation is implemented, then hydraulic pressure management is improved, but device complexity increases

Engineering Contradiction:
Improveautomated pressure managementVSAvoidcontrol system complexity
Core Design Contradiction:
Extent of automationVSDevice complexity

Solution Approach 1:

The controller serves multiple functions: it monitors pressure sensor signals, detects tool detachment events, controls relief valve actuation, and manages overall hydraulic circuit pressure. By making the controller multi-functional, the system achieves automated pressure management without adding separate dedicated components for each function

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

Solution Approach 2:

The system uses a pressure threshold parameter that the controller compares against real-time pressure sensor readings. When pressure exceeds the threshold or when tool detachment is detected, the controller changes the state of the relief valve from closed to open. This parameter-based control simplifies the automation logic while maintaining effective pressure management

Inventive Principle:
Principle #35Parameter changes

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

Enables efficient and automated attachment and detachment of work tools by managing hydraulic pressure, reducing manual effort and preventing tool drift or damage due to thermal expansion.

Implementation Method 1

a relief valve fluidly connected to the quick coupler valve block and to the fluid reservoir... automatically actuate opening of the relief valve... until the target pressure is reached

Methodology Applied
Scientific EffectPressure gradient: Pressure Gradient

Data Source

PatentEP4565749B1Automated work tool depressurization circuit and method
Publication Date: 2026.04.01 CATERPILLAR INC
  • EP4565749B1 patent drawingFigure 1
  • EP4565749B1 patent drawingFigure 2~3
  • EP4565749B1 patent drawingFigure 4

AI summary

Disclosed is a control system (101) for depressurizing a work tool auxiliary circuit (400) fluidly connected to a work tool (116) coupled to a work machine (100) by a quick coupler (114). The system (101) may comprise a controller (120) configured to: receive an unlock signal for the work tool (116); receive tool data associated with the work tool (116), the tool data including a target pressure for the work tool auxiliary circuit (400) or a release duration for the relief valve (408); and in response to the unlock signal and the tool data, automatically actuate opening of the relief valve (408) (a) for the release duration or (b) until the target pressure is reached in the work tool auxiliary circuit (400) or machine-side circuit (412) or (c) to reach and maintain the target pressure in the work tool auxiliary circuit (400) or machine-side circuit (412).