Load-Sensing Fluid Circuit Using an Accumulator for Pressure Compensation
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Solution Overview
Problem
In fluid circuits with load sensing systems, high load pressures require large hydraulic pumps, leading to degraded energy efficiency.
Innovation Solution
A fluid circuit with a pressure fluid source, multiple actuators, a direction switching valve, and a discharge amount control mechanism that includes an accumulator and a pressure reduction valve, where the load sensing valve adjusts based on pressure differences, and an adjustment means adjusts the control amount based on accumulator pressure, ensuring the supply pressure is higher than the maximum load pressure by a target difference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a large hydraulic pump is used to handle high load pressures, then the fluid circuit can respond to high load pressures, but energy efficiency is degraded
Solution Approach 1:
The accumulator stores pressure fluid in advance during periods of low demand, so that when high load pressure is required, the pre-stored high-pressure fluid can be immediately supplied without requiring the hydraulic pump to operate at high power continuously. This preliminary storage of energy resolves the contradiction between handling high pressure and maintaining energy efficiency.
Solution Approach 2:
The system changes the operational parameters of the hydraulic pump by using the accumulator to decouple the pump's operating pressure from the instantaneous load pressure requirements. The pump operates at optimized parameters while the accumulator handles pressure fluctuations, improving overall energy efficiency while maintaining the ability to respond to high load pressures.
2Reliability
If the supply pressure is constantly higher than maximum load pressure by target pressure difference, then the direction switching valve can operate properly, but energy wastage increases
Solution Approach 1:
The accumulator acts as an intermediary between the hydraulic pump and the direction switching valve, buffering pressure fluctuations. This allows the system to maintain reliable valve operation without requiring the pump to continuously maintain excessively high supply pressure, thereby reducing energy wastage while ensuring proper valve function.
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 enhances energy efficiency by compensating for output pressure using the accumulator's discharge capability, allowing the fluid circuit to respond effectively to load pressure fluctuations while minimizing energy wastage.
Implementation Method 1
an accumulator (60) adapted to accumulate part of return oil from the actuators (8, 9), the accumulator (60) being adapted to discharge hydraulic oil from the accumulator (60) to the oil path (22)
Implementation Method 2
the electromagnetic proportional pressure reduction valve (50) adapted to reduce the actuator-side pressure guided by the pilot pipe line (20) based on the internal pressure of the accumulator (60)
Implementation Method 3
the degree of opening of the load sensing valve (41) is adjusted such that a difference between the supply pressure of the hydraulic pump (2) and the actuator maximum load pressure, i.e., a pressure difference (also referred to as a direction switching valve pressure difference)
Data Source
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AI summary
There is provided a high-energy-efficiency fluid circuit using a load sensing system. A fluid circuit includes a pressure fluid source 2 configured to supply pressure fluid, multiple actuators 8, 9 connected to the pressure fluid source 2, a direction switching valve 6, 7 configured to switch a supply destination of the pressure fluid supplied from the pressure fluid source 2, and a discharge amount control mechanism 41, 42 configured to control the output pressure of the pressure fluid source 2 such that a pressure difference ΔP between the output pressure of the pressure fluid source and the maximum load pressure of the load pressures of the multiple actuators reaches a target value ΔPt. The fluid circuit further includes an accumulator 60 configured to accumulate part of return fluid from the actuators 8, 9. The accumulator 60 can discharge the accumulated pressure fluid to a pressure-fluid-source-side flow path 22 of the direction switching valve 6, 7. Adjustment means 50 configured to adjust a control amount of the pressure fluid source 2 based on the pressure of the accumulator 60 is further provided.