Hydraulic Pump Allocation Control for Dual-Engine Excavators

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Solution Overview

Problem

Extra-large mining excavators with two engines face inefficiencies due to uneven hydraulic actuator loads, requiring larger engines to maintain high work efficiency, which is not practical for downsizing.

Innovation Solution

A construction machine with a hydraulic closed-circuit system that selectively connects bidirectionally variable displacement hydraulic pumps from two engines to hydraulic actuators, using a controller to allocate engine loads and optimize pump connections based on estimated maximum demands, allowing for engine downsizing while maintaining high work efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If two engines are mounted in the construction machine to handle uneven hydraulic actuator loads, then work efficiency is maintained, but engine size cannot be reduced

Engineering Contradiction:
Improvework efficiencyVSAvoidengine size
Core Design Contradiction:
ProductivityVSWeight of moving object

Solution Approach 1:

The patent implements dynamic allocation of hydraulic pumps to actuators based on real-time load conditions. The controller continuously monitors actuator load demands and dynamically reassigns pumps between engines to balance the load distribution. This dynamic adjustment allows the system to adapt to varying operational conditions, ensuring both engines operate at optimal utilization rates and enabling engine downsizing while maintaining productivity.

Inventive Principle:
Principle #15Dynamics

2Speed

If hydraulic pumps are selectively connected to hydraulic actuators via solenoid selector valves, then high-speed operation is achieved, but complex control systems are required

Engineering Contradiction:
Improveoperation speedVSAvoidcontrol system complexity
Core Design Contradiction:
SpeedVSDevice complexity

Solution Approach 1:

The controller receives feedback signals from various sensors monitoring hydraulic actuator positions, pressures, and flow rates. Based on this feedback, the controller automatically adjusts pump connections through selector valves to optimize system performance. This closed-loop control enables high-speed operation while managing system complexity through intelligent automation rather than complex mechanical linkages.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The controller acts as an intermediary between the hydraulic pumps and actuators, managing the complex switching logic through software algorithms. Rather than requiring complex mechanical switching mechanisms, the controller processes load demand information and orchestrates pump-actuator connections electronically, simplifying the physical system while enabling sophisticated control strategies.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP3779065B1Construction machinery
Publication Date: 2023.03.01 HITACHI CONSTRUCTION MACHINERY CO LTD
  • EP3779065B1 patent drawingFigure 1
  • EP3779065B1 patent drawingFigure 2
  • EP3779065B1 patent drawingFigure 3

AI summary

An object of the present invention is to provide a construction machine that has a hydraulic closed-circuit system mounted therein and capable of selectively connecting some of a plurality of hydraulic pumps driven by two engines to any one of a plurality of hydraulic actuators and that can downsize the engines while maintaining high work efficiency. A controller 80 includes an actuator/engine allocation computing section F6 that, at the time of connecting closed-circuit pumps that are not connected to any of the hydraulic actuators 1, 3, 5, and 7 to any one of the hydraulic actuators, allocates closed-circuit pumps driven by a right engine 9b to the one hydraulic actuator in a case in which an estimated maximum load on a left engine 9a is heavier than an estimated maximum load on the right engine, and allocates closed-circuit pumps driven by the left engine to the one hydraulic actuator in a case in which the estimated maximum load on the right engine is heavier than the estimated maximum load on the left engine.