Boom Cylinder Energy Recovery with Pressure-Boost Valve Control
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Solution Overview
Problem
Existing hydraulic energy regeneration systems for work machines face issues where controlling the communication between the bottom and rod sides of a boom cylinder to boost pressure can lead to overload relief valve activation, potentially causing the boom to inadvertently fall, and generate discomforting changeover shocks during pressure regulation.
Innovation Solution
A hydraulic energy regeneration system that includes a communication pressure boost passage, a boost valve for regulating pressure and flow rate, and a controller that adjusts the boost valve's opening degree based on detected pressure and operation signals to prevent overload and minimize shocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the bottom side and rod side of the boom cylinder are controlled to communicate with each other to boost bottom pressure for improving regeneration efficiency, then energy recovery efficiency is improved, but the bottom pressure may reach the overload relief set pressure causing the boom to inadvertently fall
Solution Approach 1:
The communication control valve is controlled to dynamically adjust the communication between bottom side and rod side based on real-time pressure feedback. When bottom pressure approaches the overload relief set pressure, the valve gradually reduces or interrupts communication to prevent boom inadvertent fall, while maintaining communication during normal operation to boost pressure and improve energy recovery efficiency.
Solution Approach 2:
A pressure detector monitors the bottom pressure of the boom cylinder in real-time and provides feedback to the controller. The controller uses this feedback to adjust the communication control valve, creating a closed-loop control system that prevents bottom pressure from reaching the overload relief set pressure while maximizing energy recovery efficiency.
2Reliability
If the communication between bottom side and rod side is suddenly interrupted to suppress pressure boosting when bottom pressure nears overload relief set pressure, then overload prevention is achieved, but a changeover shock is generated causing operator discomfort
Solution Approach 1:
The communication control valve performs periodic or incremental interruption of communication rather than sudden complete interruption. The valve gradually reduces the communication opening degree in steps or over time, allowing pressure to be released in a controlled manner that prevents both overload and sudden shocks that would cause operator discomfort.
Solution Approach 2:
The system provides beforehand cushioning by gradually reducing the communication opening degree before completely interrupting it. This gradual reduction acts as a cushion that prevents sudden pressure changes and the associated shocks, while still achieving the goal of preventing bottom pressure from reaching the overload relief set pressure.
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 effectively prevents the boom cylinder's pressure from reaching overload relief set pressure and reduces changeover shocks, ensuring stable operation and improved usability even under high loads.
Implementation Method 1
a communication pressure boost passage that can boost a pressure of a discharge-side hydraulic fluid by communicating a discharge side and a suction side of the hydraulic cylinder with each other during the own weight fall of the driven body
Implementation Method 2
a communication pressure boost valve that is disposed in the communication pressure boost passage and that can regulate one of or both of a pressure and a flow rate of the communication pressure boost passage
Implementation Method 3
a hydraulic motor that is driven by the hydraulic fluid from the boom cylinder; a power generator that is mechanically coupled to the hydraulic motor
Implementation Method 4
a power generator that is mechanically coupled to the hydraulic motor; and an electrical storage device that stores the electric energy generated by the power generator
Data Source
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AI summary
A hydraulic energy regeneration system for a work machine for boosting a pressure of a return hydraulic fluid of a hydraulic cylinder and regenerating the hydraulic fluid, prevents a bottom pressure from reaching an overload relief set pressure and suppresses a changeover shock to ensure favorable operability. The hydraulic energy regeneration system for the work machine, includes: a communication pressure boost passage that can boost a pressure of a discharge-side hydraulic fluid by communicating a discharge side and a suction side of the hydraulic cylinder with each other during an own weight fall of a driven body; a communication pressure boost valve that is disposed in the communication pressure boost passage and that can regulate one of or both of a pressure and a flow rate of the communication pressure boost passage; a reuse-side line and a reuse control valve or a regeneration-side line and a regeneration control valve that can regenerate a hydraulic fluid discharged from the hydraulic cylinder during the own weight fall of the driven body; and a controller. The controller is configured to reduce an opening degree of the communication pressure boost valve in response to an increase of the discharge-side pressure of the hydraulic cylinder right after the discharge-side pressure reaches a preset high load set pressure, and gradually reduces the opening degree of the communication pressure boost valve with passage of time.