Close-Center Hydraulic Control for Construction Equipment Joysticks

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Solution Overview

Problem

Existing construction equipment control systems, such as open-center and load sensing hydraulic systems, limit control freedom and result in inefficient fuel consumption and increased noise and vibration due to constant engine operation, with manual methods for controlling actuators being prone to degradation in varying work environments.

Innovation Solution

Implementing a close-center hydraulic system with electronic or hydraulic joysticks and electronic proportional control valves to convert input signals into speed signals for actuators, allowing independent flow control and automatic operation, including a teach & play back function for standardized work reproduction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If mechanical hydraulic control systems (open-center or load sensing) are used to control actuators, then the system structure is simple and reliable, but the degree of freedom of control is limited and fuel efficiency is degraded due to excessive pump and engine operation

Engineering Contradiction:
Improvecontrol freedomVSAvoidfuel efficiency
Core Design Contradiction:
Ease of operationVSUse of energy by moving object

Solution Approach 1:

The patent replaces mechanical hydraulic control systems with an electronic control system. Electronic proportional control valves are used instead of mechanical flow control units, and electronic joysticks are used instead of mechanical joysticks. This substitution enables independent control of each flow path through electronic signals, providing full degree of freedom for control while optimizing pump and engine operation to improve fuel efficiency.

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

Solution Approach 2:

The patent divides the hydraulic control system into independent flow paths, with each actuator having its own electronic proportional control valve. This segmentation allows each flow path to be controlled independently according to actual workload requirements, enabling precise control freedom for each actuator while avoiding excessive pump operation and improving overall fuel efficiency.

Inventive Principle:
Principle #1Segmentation

2Ease of manufacture

If mechanical hydraulic control systems are used, then the system implementation is straightforward, but control precision and adaptability to varying work conditions are limited

Engineering Contradiction:
Improvesystem implementationVSAvoidadaptability to work conditions
Core Design Contradiction:
Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The patent implements a dynamic control system where electronic proportional control valves can continuously adjust flow rates based on electronic signals from electronic joysticks. The control system adapts to varying work conditions by independently controlling each flow path according to actual requirements, providing both ease of manufacture through standardized electronic components and high adaptability to different work environments.

Inventive Principle:
Principle #15Dynamics

3Ease of operation

If the engine throttle lever maintains a predetermined value regardless of work speed or load degree, then the control operation is simple, but fuel is unnecessarily consumed and noise and vibration are generated

Engineering Contradiction:
Improvecontrol operation simplicityVSAvoidnoise and vibration
Core Design Contradiction:
Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The patent replaces the mechanical throttle lever system with an electronic control system. The engine speed is now controlled by electronic signals from the electronic joystick through the control unit, which adjusts the hydraulic pump output accordingly. This eliminates the need for a fixed throttle position, allowing the engine to operate at optimal speeds for different work conditions, reducing noise and vibration while maintaining simple control operation through the electronic interface.

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

This solution enhances control precision and efficiency, reduces worker fatigue, improves fuel efficiency, and maintains consistent performance across varying load conditions, enabling automated operation of construction equipment with improved safety and work efficiency.

Implementation Method 1

a hydraulic pump generating hydraulic pressure by using power of the engine

Methodology Applied
Scientific EffectHydraulic pressure generation: Hydraulic Press

Implementation Method 2

electronic proportional control valve, which converts an electric signal into a degree of opening of the valve

Methodology Applied
Scientific EffectElectro-hydraulic conversion: Valve

Implementation Method 3

electronic joystick, which converts an input signal into an electric signal in proportion to a speed

Methodology Applied
Scientific EffectSignal conversion:

Data Source

PatentEP2933387B1Automatic control system and method for joystick control-based construction equipment
Publication Date: 2019.08.14 HD HYUNDAI CONSTR EQUIP CO LTD
  • EP2933387B1 patent drawingFigure 1
  • EP2933387B1 patent drawingFigure 2
  • EP2933387B1 patent drawingFigure 3

AI summary

According to the present invention, a hydraulic system of construction equipment is implemented as a close center system, which converts an input signal of an electric or hydraulic joystick into a speed signal of a work apparatus, and controls a speed of the work apparatus regardless of an external load condition, thereby minimizing fatigue of a worker to improve work efficiency, improving a work apparatus operation ability of an unskilled person, and patterning standardized work to implement automation of construction equipment.