Switchable Hydraulic Pump Displacement for Steering and Loading

Solution Overview

Problem

Hydraulic systems with load-sensing fixed/variable-displacement face performance and efficiency issues compared to fixed-displacement systems, particularly in steering performance and loading efficiency, necessitating a balance between energy conservation and performance.

Innovation Solution

A hydraulic system switchable between fixed-displacement and fixed/variable-displacement modes, utilizing a control method that includes a load-sensing system, a fixed/variable-displacement switching control valve, and a displacement changing mechanism to adjust pump displacement based on differential pressure thresholds, enabling seamless transitions between modes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a load-sensing fixed/variable-displacement hydraulic system is used to achieve energy conservation, then energy efficiency is improved, but steering performance and loading efficiency deteriorate

Engineering Contradiction:

Improveenergy conservationVSAvoidsteering performance

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The system dynamically switches between fixed-displacement and variable-displacement modes based on operational requirements. A switching control valve responds to differential pressure signals to automatically adjust the pump's displacement mode, enabling the system to adapt between energy-saving mode (variable displacement) and high-performance mode (fixed displacement) for steering and loading operations

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the displacement parameter of the hydraulic pump based on operational conditions. By detecting differential pressure across the pump and switching between fixed and variable displacement states, the system optimizes the balance between energy consumption and performance requirements for different working scenarios

Inventive Principle:

Principle #35Parameter changes

2Loss of energy

If a load-sensing fixed/variable-displacement hydraulic system is used to achieve energy conservation, then energy efficiency is improved, but loading efficiency deteriorates

Engineering Contradiction:

Improveenergy conservationVSAvoidloading efficiency

Core Design Contradiction:

Loss of energyVSProductivity

Solution Approach 1:

The system dynamically switches between fixed-displacement and variable-displacement modes based on operational requirements. A switching control valve responds to differential pressure signals to automatically adjust the pump's displacement mode, enabling the system to adapt between energy-saving mode (variable displacement) and high-performance mode (fixed displacement) for loading operations

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the displacement parameter of the hydraulic pump based on operational conditions. By detecting differential pressure across the pump and switching between fixed and variable displacement states, the system optimizes the balance between energy consumption and loading efficiency requirements

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

Achieves a better balance between energy conservation and performance by allowing operators to switch between fixed and variable displacement modes, enhancing system efficiency and reliability.

Implementation Method 1

when a differential pressure between input pressure of the first control port and input pressure of the second control port is greater than a first threshold, the output main path is in fluid communication with the input port of the control cylinder; when the differential pressure between the input pressure of the first control port and the input pressure of the second control port is less than the first threshold, the input port of the control cylinder is in fluid communication with the oil return port of the oil tank

Methodology Applied

Scientific EffectDifferential pressure: Pressure Gradient

Implementation Method 2

both the working oil line and the load-sensing circuit are in fluid communication with the fixed/variable-displacement switching control valve; the load-sensing valve is in fluid communication with the output main path, the oil return port of the oil tank and an input port of the control cylinder

Methodology Applied

Scientific EffectHydraulic pressure transmission: Hydraulic Press

Data Source

PatentEP4234951B1Quantitative and constant-variable switchable hydraulic system, and control method therefor and operation machine

Publication Date: 2025.07.23 SHANGHAI SANY HEAVY IND

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AI summary

Disclosed are a hydraulic system, a control method and a working machine. The hydraulic system includes an oil tank, a working pump, a control cylinder controlling a displacement changing mechanism, a working oil line communicating with an output main path of the working pump, a load-sensing system including a load-sensing circuit outputting hydraulic pressure based on load, a load-sensing valve and a switching-control valve switchable between a first-valve-position and a second-valve-position. When differential pressure between the first and second control ports is greater than a first threshold, the output main path communicates with an input port of the control cylinder; when it is less than the first threshold, the input port communicates with an oil return port of the oil tank. Based on this, operators can switch the hydraulic system between the fixed-displacement mode and the fixed/variable-displacement mode, thereby achieving a better balance between energy conservation and performance.