Hydraulic System with Direct Pump Control and Energy Recuperation
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Solution Overview
Problem
Traditional hydraulic systems for wheel loaders are energy inefficient due to the need for pressure drops in load sensing systems, which require pumps to provide more energy than necessary for hydraulic cylinder operations.
Innovation Solution
A hydraulic system with an actuator pump directly controlling hydraulic cylinders, eliminating the need for pressure drops by using a hydraulic accumulator pressurized by a separate pump, allowing the actuator pump to work solely for cylinder power and enabling energy recuperation during lowering of the implement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a load sensing system is used to control hydraulic cylinders, then the hydraulic system can respond to load changes, but the pump must provide more energy than necessary due to required pressure drops
Solution Approach 1:
The patent extracts the pressure control function from the actuator pump by introducing a separate further pump dedicated to pressurizing the hydraulic accumulator. This allows the actuator pump to operate without the energy-wasting pressure drops required by traditional load sensing systems, as pressure regulation is handled independently by the further pump through the accumulator.
Solution Approach 2:
The hydraulic accumulator acts as an intermediary energy storage device between the further pump and the hydraulic cylinder. It stores pressurized hydraulic fluid and releases it when needed, eliminating the need for the actuator pump to continuously maintain high pressure and thereby reducing energy consumption while still enabling rapid response to load changes.
2Ease of operation
If the hydraulic cylinder is directly controlled by the actuator pump with pure pump control, then the rate of movement is precisely controlled, but an additional further pump is required for the hydraulic accumulator
Solution Approach 1:
The patent segments the hydraulic system into two independent pumping functions: the actuator pump dedicated to precise flow control of the hydraulic cylinder, and the further pump dedicated to pressurizing the hydraulic accumulator. This segmentation allows each pump to be optimized for its specific function, with the actuator pump providing precise movement control without the complexity of integrated pressure control.
3Use of energy by moving object
If energy recuperation is implemented during lowering of the implement, then energy efficiency is improved, but the hydraulic system requires a hydraulic accumulator for energy storage
Solution Approach 1:
The patent converts the potentially harmful effect of uncontrolled potential energy release during implement lowering into a beneficial energy source. The hydraulic accumulator captures and stores the energy from the lowering implement, which would otherwise be wasted, and makes it available for future use, thereby improving overall energy efficiency of the 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 configuration reduces energy consumption by eliminating pressure drops and allowing energy recovery, enhancing the efficiency of wheel loader operations.
Implementation Method 1
a hydraulic accumulator for suspension of the implement, the hydraulic accumulator being arranged to be selectively connectable to the first port
Implementation Method 2
an actuator pump arranged to provide hydraulic fluid to the hydraulic cylinder
Implementation Method 3
the hydraulic accumulator being arranged to be pressurised by the further pump
Data Source
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AI summary
The invention provides a hydraulic system for moving an implement (5) of a working machine, - the hydraulic system comprising a hydraulic cylinder (701, 721) with a cylinder and a piston which is adapted to move in the cylinder to thereby move the implement (5) relative to a body structure (2) of the working machine, and an actuator pump (702, 722) arranged to provide hydraulic fluid to the hydraulic cylinder (701, 721), the hydraulic cylinder (701, 721) having a first port (703, 723) and a second port (704, 724) adapted to be in fluid communication with the actuator pump (702, 722), - the hydraulic cylinder (701, 721) and the actuator pump (702, 722) being arranged so that the hydraulic cylinder (701, 721) is directly controlled by the actuator pump (702, 722) so that the rate of movement of the piston of the hydraulic cylinder is purely pump controlled, - the hydraulic system further comprising a hydraulic accumulator (731) for suspension of the implement (5), which hydraulic accumulator (731) is arranged to be selectively connectable to the first port, - the hydraulic system further comprising a further pump (801) in addition to the actuator pump (702), the hydraulic accumulator (731) being arranged to be pressurised by the further pump (801).