Hydraulic Pump Flow Control to Cut Leakage in Work Machines

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Solution Overview

Problem

The existing hydraulic control systems for work machines face energy wastage due to increased leakage flow rates at higher delivery pressures, particularly when the merging cancellation valve reduces delivery pressure to manage load pressure, leading to inefficiencies in flow rate control of hydraulic pumps.

Innovation Solution

The system decreases the delivery flow rate of the first hydraulic pump with increasing load on the actuator, using a controller to enlarge the communication area between the pump and the tank, thereby reducing delivery pressure and total leakage flow rate, and employs a flow rate control mechanism to manage the delivery flow rates of multiple hydraulic pumps effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the merging cancellation valve is operated to reduce delivery pressure of the third hydraulic pump, then the load on the third hydraulic pump is reduced and delivery flow rate of other hydraulic pumps is increased, but the leakage flow rate increases due to higher delivery pressure values

Engineering Contradiction:
Improvedelivery flow rateVSAvoidleakage flow rate
Core Design Contradiction:
PowerVSLoss of energy

Solution Approach 1:

The patent applies parameter changes by dynamically adjusting the delivery flow rate of the third hydraulic pump based on the operating state (merging or non-merging) and load pressure. The control device modifies pump parameters (flow rate) to optimize system performance, reducing leakage losses while maintaining required delivery flow rates through precise parameter control

Inventive Principle:
Principle #35Parameter changes

2Ease of operation

If positive control is applied to make the third hydraulic pump deliver flow rate according to arm lever operation amount, then the pump responds to operator input, but the inoperative flow rate increases causing energy waste

Engineering Contradiction:
Improveresponse to operator inputVSAvoidenergy waste
Core Design Contradiction:
Ease of operationVSLoss of energy

Solution Approach 1:

The patent implements feedback control by using a control device that continuously monitors the operating state (merging/non-merging) and load pressure, then adjusts the delivery flow rate of the third hydraulic pump accordingly. This feedback mechanism ensures the pump delivers only the necessary flow rate, eliminating inoperative flow and reducing energy waste while maintaining operational responsiveness

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system transitions from static positive control to dynamic control where the delivery flow rate is continuously adjusted based on real-time operating conditions. The control device dynamically modifies pump performance parameters to match actual system needs, preventing energy waste from delivering unnecessary flow rates

Inventive Principle:
Principle #15Dynamics

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

This approach results in an energy-saving hydraulic control system by minimizing leakage and void flow rates, enhancing operational efficiency and reducing energy consumption in work machines.

Implementation Method 1

the first control valve is operated in response to a delivery pressure of the first hydraulic pump

Methodology Applied
Scientific EffectHydraulic pressure: Pressure Gradient

Implementation Method 2

enlarge a communication area between the first hydraulic pump and the tank

Methodology Applied
Scientific EffectFluid flow: Hydraulic Press

Data Source

PatentEP3217019B1Hydraulic control device for operating machine
Publication Date: 2021.06.16 HITACHI CONSTRUCTION MACHINERY CO LTD
  • EP3217019B1 patent drawingFigure 1
  • EP3217019B1 patent drawingFigure 2
  • EP3217019B1 patent drawingFigure 3~4

AI summary

The invention provides an energy-saving hydraulic control system for a work machine including a specific actuator that can supply a hydraulic fluid from a plurality of hydraulic pumps. The hydraulic control system for a work machine includes: a first hydraulic pump and a second hydraulic pump capable of communicating with a first hydraulic actuator; a first control valve capable of returning a hydraulic fluid delivered by the first hydraulic pump to a tank; and a load detection section that detects a load on the first hydraulic actuator. The hydraulic control system includes: a control valve drive section that drives the first control valve such that a communication area between the first hydraulic pump and the tank is enlarged corresponding to an increase in the load on the first hydraulic actuator; and a flow rate control section that, during supply of the hydraulic fluid from the first hydraulic pump and the second hydraulic pump to the first hydraulic actuator, controls to reduce a delivery flow rate of the first hydraulic pump corresponding to an increase in the load on the first hydraulic actuator.