Hydraulic Pump-Accumulator Switching for Low-Shock Actuation
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Solution Overview
Problem
The existing hydraulic drive systems in construction machinery experience large shocks during transitions from accumulator charging to hydraulic pump-driven operation due to pressure differences, compromising operator operability.
Innovation Solution
A hydraulic drive system with a tank, hydraulic pump, actuator, accumulator, and control valves, controlled by a controller that manages fluid flow and pressure to synchronize pump and actuator communication, minimizing pressure discrepancies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the hydraulic pump directly supplies pressure oil to the hydraulic actuator during switching from accumulator charging to actuator driving, then the response speed of the hydraulic actuator is improved, but large shock occurs due to pressure difference
Solution Approach 1:
The controller performs preliminary action by detecting the pressure of the hydraulic pump and delaying the opening of the actuator flow control valve until the pump pressure decreases to a safe level. This preliminary pressure monitoring and delayed valve opening prevents the direct connection of high-pressure pump to low-pressure actuator, thereby avoiding shock while maintaining fast response capability.
Solution Approach 2:
The controller acts as an intermediary between the hydraulic pump and the actuator flow control valve. It monitors pump pressure and intelligently controls the valve opening timing, serving as a mediator that coordinates the pressure levels between pump and actuator to prevent shock during switching from accumulator charging to pump-driven operation.
2Reliability
If the accumulator is continuously charged by the hydraulic pump, then the accumulator pressure is maintained, but the hydraulic pump and hydraulic actuator cannot be communicated when operation is needed
Solution Approach 1:
The system dynamically switches between two operational modes: accumulator charging mode (when no operation signal is received) and actuator driving mode (when operation signal is received). The controller dynamically adjusts the opening/closing states of the accumulator flow control valve and actuator flow control valve based on real-time operational needs, enabling the system to adapt between maintaining pressure and providing responsive actuator operation.
Solution Approach 2:
The controller changes the operational parameters of the flow control valves based on system state. When accumulator charging is needed, the accumulator flow control valve is opened and actuator flow control valve is closed. When actuator operation is needed, the controller delays opening the actuator flow control valve until pump pressure decreases, thereby changing the pressure parameter timing to prevent shock while ensuring operational responsiveness.
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
The system suppresses shocks during transitions, enhancing the operability of hydraulic actuators by ensuring synchronized pressure management.
Implementation Method 1
a hydraulic pump for sucking in and discharging hydraulic fluid from the tank
Implementation Method 2
an accumulator for accumulating pressure oil discharged from the hydraulic pump
Data Source
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AI summary
The present invention aims to provide a hydraulic drive system capable of improving the operability of a hydraulic actuator by suppressing shock when switching from the state where the hydraulic pump accumulates in the accumulator to the state where the hydraulic pump drives the hydraulic actuator. Therefore, when the detection value of the first pressure sensor falls below a predetermined first threshold without an operation signal being input, the controller communicates the hydraulic pump to the accumulator while interrupting the hydraulic pump and hydraulic actuator and interrupting the hydraulic pump and tank. When an operation signal is input while pressure oil is being supplied from the hydraulic pump to the accumulator, the controller reduces the opening of the accumulator flow control valve and communicates the hydraulic pump to the tank while interrupting the hydraulic pump and the hydraulic actuator. Then, after a predetermined time has elapsed or after the pressure of the hydraulic pump has decreased, the controller communicates the hydraulic pump and the hydraulic actuator.