Dynamic Load Sensing Hydraulic Pump Control
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Solution Overview
Problem
Existing load sensing systems in working machines, such as wheel loaders, face inefficiencies in energy consumption and reliability due to fixed control pressures, which do not adapt well to different working positions or conditions, leading to drag losses and instability in hydraulic systems.
Innovation Solution
A load sensing system with an electrically controlled pump control valve that adjusts control pressure dynamically based on operational demands, allowing for lower standby pressures, reduced control losses, and enhanced stability by maintaining maximum pressure during electronics malfunctions, while using position sensors for end position damping and power control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed control pressure of 20-30 bar is maintained in the load sensing system, then the system ensures sufficient lubricating and cooling ability, but the system experiences increased drag losses and higher energy consumption during idle operations
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed control pressure system to a dynamic pressure control system. The electronically controlled pump control valve (LS valve) continuously adjusts the pump output pressure based on real-time load sensing feedback, allowing the system to maintain only the necessary pressure for current operational demands rather than a constant high pressure, thereby reducing drag losses while ensuring reliability when needed
Solution Approach 2:
The patent implements parameter changes by varying the control pressure parameter dynamically. The system changes the pressure parameter from a fixed 20-30 bar to a variable value determined by actual load conditions plus a minimal offset (5-10 bar), allowing optimization of energy consumption while maintaining sufficient pressure for lubrication and cooling only when required
2Stability of the object's composition
If a higher control pressure of 20-30 bar is used to ensure system stability, then the hydraulic system maintains adequate lubrication and cooling, but the pump operates at higher idle pressure consuming more energy
Solution Approach 1:
The system uses dynamic pressure adjustment where the pump control valve responds to load sensing signals to maintain system stability only at the necessary pressure level. During idle conditions, the pressure dynamically drops to minimal levels (5-10 bar offset), reducing energy consumption while the electronically controlled valve ensures rapid response when stability is needed
Solution Approach 2:
The patent replaces the traditional mechanical pressure relief valve system with an electronically controlled pump control valve. This substitution allows for more precise and responsive pressure control, enabling the system to maintain stability through electronic feedback control rather than relying on constant high mechanical pressure, thereby reducing energy consumption
3Speed
If the pump maintains a constant high pressure output, then the system responds quickly to operational demands, but the system experiences increased control losses and reduced efficiency during low-flow conditions
Solution Approach 1:
The load sensing system with electronically controlled valve creates a dynamic pressure response system. When operational demand increases, pressure quickly rises to meet the demand. During low-flow conditions, pressure automatically reduces, minimizing control losses. This dynamic behavior maintains fast response speed while eliminating the need to sustain high pressure during idle periods
Solution Approach 2:
The system implements feedback control through load sensing that continuously monitors actual hydraulic load conditions and feeds this information back to the pump control valve. This feedback mechanism allows the system to adjust pressure in real-time based on actual needs, maintaining quick response capability while reducing control losses by avoiding unnecessary high pressure during low-demand periods
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 achieves more efficient energy consumption, reduced drag losses, improved system stability, and enhanced operational reliability by dynamically adjusting control pressures and maintaining maximum hydraulic power availability, even in case of electronics failures.
Implementation Method 1
an electrically controlled pump control valve (241) arranged for controlling opening degree on a conduit (247) connected between an outlet conduit (245) from the pump (205) and a conduit (251) which in its turn is connected to the pump (205) for controlling it with a hydraulic signal
Implementation Method 2
a pressure sensor (239) for detecting a pressure which is indicative of an output pressure from the pump
Implementation Method 3
a pump (205) adapted to supply actuators (108, 109, 220) with pressurized hydraulic fluid via a hydraulic circuit
Data Source
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AI summary
The invention relates to a load sensing system (201), comprising - a first assembly (203) of actuators (108, 109) for controlling a first hydraulic function, - a pump (205) adapted to supply said actuators with pressurized hydraulic fluid, - an electrically controlled valve (241) adapted to control the output pressure of the pump via a hydraulic signal, - a first pressure sensor (229, 231) for detecting a load pressure of the first actuator assembly (203), and - a control unit (213) adapted to receive a signal with information about the load pressure detected by the first pressure sensor (229, 231) and to generate a control signal, corresponding to the detected load pressure, to the electrically controlled valve (241).