Hydraulic Pump Allocation Controller for Work Machine Valve Switching

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Solution Overview

Problem

Conventional hydraulic systems in work machines, such as hydraulic excavators, experience increased vehicle body vibration, worsened operability, and shortened component life due to excessive switching of switching valves caused by unnecessary pressure variations during pump reconnection, leading to inefficient energy management.

Innovation Solution

A work machine system with a controller that includes a priority order calculating circuit to optimize the allocation of hydraulic pumps to actuators, allowing for reduced unnecessary switching control by maintaining pump allocation across actuators during changes in operational demands, thereby minimizing valve switching and pressure variations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If hydraulic pumps are reallocated according to priority order map when operational demands change, then pump allocation efficiency is improved, but the number of valve switching increases causing vehicle body vibration and component deterioration

Engineering Contradiction:
Improvepump allocation efficiencyVSAvoidcomponent life
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The controller determines the required number of hydraulic pumps in advance based on operation lever positions before actual pump allocation occurs. This preliminary determination allows the system to prepare allocation strategies that minimize valve switching while ensuring adequate pump capacity is available when needed.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system dynamically adjusts pump allocation based on real-time operational demands detected through operation lever positions. The controller continuously monitors lever positions and modifies pump connections accordingly, enabling adaptive pump allocation that responds to changing work conditions without excessive valve switching.

Inventive Principle:
Principle #15Dynamics

2Use of energy by moving object

If switching valves are controlled frequently to optimize pump allocation, then energy management efficiency is improved, but vehicle body vibration increases and operability worsens

Engineering Contradiction:
Improveenergy management efficiencyVSAvoidoperability
Core Design Contradiction:
Use of energy by moving objectVSEase of operation

Solution Approach 1:

The controller calculates the required number of hydraulic pumps based on operation lever positions before executing pump allocation. This advance determination enables the system to optimize energy management by pre-planning pump connections, thereby reducing the frequency of valve switching and minimizing vehicle body vibration that would otherwise degrade operability.

Inventive Principle:
Principle #10Preliminary action

3Adaptability or versatility

If the number of hydraulic pumps is increased to cover all actuator demands simultaneously, then actuator drive capability is improved, but pump size and system complexity increase

Engineering Contradiction:
Improveactuator drive capabilityVSAvoidsystem complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The system uses multiple variable displacement hydraulic pumps with adjustable discharge rates that can be dynamically controlled based on real-time actuator demands. This dynamic adjustment capability allows the system to maintain adequate drive capability for all actuators without requiring an excessive number of large fixed-displacement pumps, thereby reducing overall system complexity.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the discharge rate parameter of variable displacement hydraulic pumps according to operational demands. By adjusting pump discharge rates dynamically, the system can accommodate varying actuator requirements without increasing the number of pumps or their sizes, thus maintaining adaptability while controlling system complexity.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3073125B1Work machine
Publication Date: 2018.09.26 HITACHI CONSTRUCTION MACHINERY CO LTD
  • EP3073125B1 patent drawingFigure 1
  • EP3073125B1 patent drawingFigure 2
  • EP3073125B1 patent drawingFigure 3

AI summary

Provided is a work machine driving device which can reduce unnecessary switching control of switching valves. The present invention is configured so that at least two closed-circuit hydraulic pumps 2a to 2f can be connected in a closed loop to any one of hydraulic actuators 7a to 7c, 10c through electromagnetic switching valves 12, in which a controller 16 includes a priority order calculating circuit 31 which calculates the allocation of the closed-circuit hydraulic pumps 2a to 2f to the hydraulic actuators 7a to 7c, 10c according to operation of operation levers 17a, 17b and a priority order map 32 determining priority connection relationships between the closed-circuit hydraulic pumps 2a to 2f and the hydraulic actuators 7a to 7c, 10c, and the priority order calculating circuit 31 selects and allocates an unallocated closed-circuit hydraulic pump 2a to 2f when the number of closed-circuit hydraulic pumps 2a to 2f to be allocated increases.