Boom Oscillation Control via Hydraulic Chamber Segmentation
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Solution Overview
Problem
Conventional solutions for reducing boom oscillations in vehicles with extended booms, such as concrete pump trucks, often rely on passive orifices or counter-balance valves that restrict hydraulic control, leading to efficiency losses and inadequate vibration mitigation, especially when external loads like concrete pumping induce oscillations.
Innovation Solution
A hydraulic system with a control strategy that uses independent directional control valves and counter-balance valves to lock one chamber and transfer vibration-canceling fluid flow to the active chamber, reducing pressure ripples and preventing drifting, while maintaining counter-balance protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If counter-balance valves are used to prevent uncommanded movement, then safety and reliability are improved, but the ability to sense and act upon pressure oscillations is restricted, leading to inadequate vibration mitigation
Solution Approach 1:
The hydraulic system is segmented into two independent control loops: one controlling the meter-in valve for boom extension and another controlling the meter-out valve for boom retraction. This segmentation allows each valve to be optimized independently - the meter-in valve can respond to pressure oscillations while the meter-out valve maintains counter-balance protection, resolving the contradiction between safety and vibration mitigation.
Solution Approach 2:
Pressure sensors are introduced as intermediaries to detect pressure oscillations in the hydraulic lines. These sensors provide feedback signals that enable the control system to actively compensate for vibrations by adjusting valve positions, allowing the system to maintain both safety protection and vibration reduction simultaneously.
2Object-affected harmful factors
If passive orifices are used to reduce boom oscillations, then vibration mitigation is improved, but efficiency is negatively impacted due to restricted hydraulic control
Solution Approach 1:
The passive mechanical orifices are replaced with an active electronic control system consisting of pressure sensors, a controller, and electronically controlled valves. This substitution eliminates the energy loss associated with fixed orifices while providing dynamic vibration compensation that adapts to varying operating conditions, improving both vibration mitigation and hydraulic efficiency.
Solution Approach 2:
Instead of using fixed orifices with constant flow restriction, the system dynamically adjusts valve openings based on real-time pressure sensor feedback. This parameter change allows the system to optimize flow conditions for each operating state, reducing energy loss while maintaining effective vibration control.
3Measurement precision
If joint position sensors are used to sense oscillations and prevent drift, then measurement precision is improved, but device complexity increases
Solution Approach 1:
Pressure sensors in the hydraulic lines serve as intermediaries that indirectly detect boom oscillations by measuring pressure fluctuations caused by boom movement. This approach provides sufficient measurement precision for vibration control without requiring direct position sensors on the boom, thereby reducing system complexity while maintaining effective oscillation detection.
Data Source
AI summary
A hydraulic system (600) and method for reducing boom dynamics of a boom (30), while providing counter-balance valve protection, includes a hydraulic cylinder (110), first and second counter-balance valves (300, 400), first and second control valves (700, 800), and first and second blocking valves (350, 450). A net load (90) is supported by a first chamber (116, 118) of the hydraulic cylinder, and a second chamber (118, 116) of the hydraulic cylinder may receive fluctuating hydraulic fluid flow from the second control valve to produce a vibratory response (950) that counters environmental vibrations (960) on the boom. The method may include measuring first pressure ripples at the second chamber and reducing a magnitude of second pressure ripples at the first chamber. The pressure ripples may be transformed into a flow command by multiplying the pressure ripples by a gain and/or phase shifting. The gain and/or the phase shifting may be adjusted by feedback. The feedback may include the second pressure ripples at the load holding chamber, a position of the hydraulic actuator, and/or an operator input. A reference signal may be filtered with a moving average filter.