Open-Circuit Hydraulic Pressure Control for Mobile Work Machines
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Solution Overview
Problem
Existing hydraulic systems for mobile work machines suffer from low energy efficiency and require cost- and maintenance-intensive hydraulic accumulators, particularly in mobile applications, and conventional drive systems have comparatively low efficiency.
Innovation Solution
A hydraulic system with an open circuit design that uses a single hydraulic machine to supply pressure medium to both working and travel hydraulics, controlled by an electronic system that selects the maximum target pressure from the working and travel hydraulic systems, allowing simultaneous operation and eliminating the need for additional hydraulic machines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a constant-pressure hydraulic system is used, then the system can supply pressure medium continuously, but energy efficiency decreases and hydraulic accumulators are required which increase cost and maintenance requirements
Solution Approach 1:
The patent applies dynamic pressure control by replacing the constant-pressure system with a variable pressure system that adjusts the hydraulic machine's output pressure according to the actual demand of working and travel hydraulics. The electronic system control continuously monitors pressure requirements and dynamically adjusts the hydraulic machine's operating parameters, ensuring pressure is supplied only when and where needed, thereby eliminating the need for energy-consuming accumulators while maintaining continuous supply reliability.
Solution Approach 2:
The system changes the pressure parameter from constant to variable by implementing electronic control that adjusts the hydraulic machine's output pressure based on real-time demands of working hydraulics and travel hydraulics. This parameter change allows the system to match pressure supply with actual consumption, reducing energy waste associated with maintaining constant pressure and eliminating the need for hydraulic accumulators.
2Adaptability or versatility
If separate hydraulic machines are used for working hydraulics and travel hydraulics, then each system can be optimized independently, but device complexity and cost increase
Solution Approach 1:
The patent implements a single hydraulic machine that serves multiple functions by supplying pressure medium to both working hydraulics and travel hydraulics. The electronic system control enables this single machine to adapt its output characteristics dynamically, effectively performing the roles of multiple dedicated machines. This multi-functionality reduces device complexity and cost while maintaining the ability to optimize both systems through centralized electronic control that responds to their respective demands.
Solution Approach 2:
The patent merges the working hydraulic system and travel hydraulic system into a single integrated hydraulic circuit powered by one hydraulic machine. This combining is enabled by the electronic system control that coordinates pressure medium distribution to both systems based on their instantaneous requirements, achieving cost-effectiveness and simplicity while preserving independent optimization capabilities through electronic regulation.
3Device complexity
If an open hydraulic circuit is used for travel hydraulics, then system simplicity and cost-effectiveness improve, but control precision and efficiency decrease
Solution Approach 1:
The patent implements feedback control in the open hydraulic circuit by using electronic sensors to monitor pressure, flow, and system state, then feeding this information back to the electronic system control. This feedback mechanism enables the control system to adjust the hydraulic machine's output and directional control valves in real-time, maintaining high control precision despite the simplicity of the open circuit design. The feedback loop ensures efficient operation by matching supply with actual demand.
Solution Approach 2:
The patent replaces complex mechanical control mechanisms with electronic control systems in the open hydraulic circuit. Electronic sensors, processors, and actuators substitute for traditional mechanical feedback and regulation mechanisms, achieving precise control of the hydraulic machine and directional valves. This electronics-based approach maintains control precision while preserving the simplicity and cost-effectiveness of the open circuit design.
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 design achieves high driving performance, cost-effectiveness, and simplicity by combining working and travel hydraulics in an open circuit, enabling efficient operation with a single hydraulic machine, even in applications with short service life and minimal temporal overlap between functions.
Implementation Method 1
a single hydraulic machine (4) for supplying pressure medium to a working hydraulic system (6) and to a travel hydraulic system (8)
Implementation Method 2
The pressure medium is supplied in an open hydraulic circuit
Data Source
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Figure 5
AI summary
The invention discloses a hydraulic system for a mobile work machine. The system has a working hydraulics arrangement and a traction hydraulics arrangement, each of which has a setpoint pressure specification, wherein the respective setpoint pressure specification is determined using means. An electronic system controller then selects the higher setpoint pressure specification and, from this, forms a setpoint pressure that is used for controlling a single hydraulic machine. The single hydraulic machine is then used simultaneously for the supply of pressure medium to the working hydraulics arrangement and to the traction hydraulics arrangement.