Coupler Cylinder Pressure Control for Reliable Bucket Locking

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Solution Overview

Problem

Existing hydraulic systems in work machines risk erroneous recognition of a locked state due to time-based termination of hydraulic oil supply, leading to potential attachment dropout, despite the attachment not being locked, which affects fuel efficiency.

Innovation Solution

A hydraulic system for work machines that includes a coupler cylinder, hydraulic pump, valve, and controller, where the controller controls the oil supply to the coupler cylinder based on pressure in the oil passage, ensuring accurate detection of the locked state and preventing wasteful fuel consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the supply of hydraulic oil is terminated by time management after a predetermined time elapses from switch operation, then fuel efficiency is improved, but erroneous recognition of locked state occurs leading to attachment dropout

Engineering Contradiction:
Improvefuel efficiencyVSAvoidlocked state recognition accuracy
Core Design Contradiction:
Use of energy by moving objectVSReliability

Solution Approach 1:

The system uses pressure feedback from the oil passage to determine when to terminate hydraulic oil supply. The controller monitors pressure changes in real-time and stops supply when pressure stabilizes, providing accurate feedback about the actual locking state rather than relying on time-based assumptions.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent replaces the time-based control mechanism with a pressure-based detection mechanism. Instead of using a timer to determine when locking is complete, the system uses pressure sensors to detect the actual mechanical state of the coupler, substituting temporal estimation with physical state measurement.

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

2Reliability

If hydraulic oil supply continues until confirmation of locked state, then reliable locking is achieved, but fuel consumption increases

Engineering Contradiction:
Improvelocked state recognition accuracyVSAvoidfuel consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The system provides continuous pressure feedback during the locking process and terminates supply as soon as the pressure indicates successful locking. This feedback mechanism allows the system to stop hydraulic oil supply at the precise moment locking is achieved, avoiding unnecessary continued supply that would waste fuel.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The pressure detection system is prepared in advance to monitor oil passage pressure during the locking operation. By having the detection mechanism ready and active, the system can immediately recognize when locking is complete and terminate supply, preventing fuel waste without delaying the locking confirmation.

Inventive Principle:
Principle #10Preliminary action

3Use of energy by moving object

If time-based termination is used for hydraulic oil supply, then fuel efficiency is improved, but system complexity increases due to need for abnormality detection

Engineering Contradiction:
Improvefuel efficiencyVSAvoidcontrol system complexity
Core Design Contradiction:
Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent replaces complex time-based control logic with simpler pressure-based control. The pressure sensor directly indicates the locking state through physical pressure changes, eliminating the need for complex timing sequences and abnormality detection algorithms, thereby reducing control system complexity while maintaining fuel efficiency.

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

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 system enhances fuel efficiency by preventing erroneous recognition of the locked state and reducing unnecessary fuel consumption, while ensuring reliable attachment locking and unlocking.

Implementation Method 1

a pressure sensor that detects pressure in the oil passage between the hydraulic pump and the coupler cylinder

Methodology Applied
Scientific EffectPressure detection:

Implementation Method 2

The hydraulic pump supplies the oil to the coupler cylinder in order to drive the coupler cylinder between the extended position and the retracted position

Methodology Applied
Scientific EffectHydraulic pressure: Hydraulic Press

Data Source

PatentEP4105390B1Hydraulic system for work machine, work machine, and method for controlling hydraulic system
Publication Date: 2025.11.05 KOMATSU LTD
  • EP4105390B1 patent drawingFigure 1
  • EP4105390B1 patent drawingFigure 2(A)~2(B)
  • EP4105390B1 patent drawingFigure 3

AI summary

A coupler cylinder (21) is driven between a locked state and an unlocked state of a bucket (6) by being supplied with hydraulic oil. A main pump (23) supplies the hydraulic oil to the coupler cylinder (21). A pressure increasing valve (25) controls the supply of the hydraulic oil to the coupler cylinder (21). A controller (30) controls drive of the pressure increasing valve (25). The controller (30) instructs the pressure increasing valve (25) to stop the supply of the hydraulic oil to the coupler cylinder (21) based on pressure in an oil passage between the main pump (23) and the coupler cylinder (21).