Boom Pilot Control Valve Layout for Bounce Reduction
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Solution Overview
Problem
Existing boom systems, particularly in vehicles like concrete pump trucks and excavators, experience undesirable dynamic behavior due to their length and mass, leading to vibrations induced by starting/stopping loads, concrete momentum, and external forces, which conventional counter-balance valves struggle to mitigate effectively without impacting efficiency.
Innovation Solution
A hydraulic system with a pair of counter-balance valves and control valves that dynamically pressurize and depressurize chambers to counteract vibrations, while ensuring safety and preventing uncommanded movements, using a valve arrangement that selectively connects and disconnects counter-balance valves to manage hydraulic fluid flow and prevent vibration transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional counter-balance valves are used to control boom movement, then safety is improved by preventing uncommanded movement, but vibration mitigation capability deteriorates
Solution Approach 1:
The hydraulic control system is divided into two independent counter-balance valves (first and second CBVs), each controlling one side of the hydraulic cylinder. This segmentation allows independent control of vibration mitigation and safety functions, where one CBV can be optimized for vibration reduction while the other maintains safety protection against uncommanded movement.
Solution Approach 2:
The system dynamically adjusts the opening pressure of the counter-balance valves based on operating conditions. The controller modifies the pilot pressure to the CBVs in real-time, enabling the valves to adapt their restrictive characteristics - being more restrictive during vibration-prone operations and less restrictive when safety is the primary concern, thus resolving the contradiction between safety and vibration mitigation.
2Object-affected harmful factors
If counter-balance valves are made more restrictive to reduce vibration, then vibration mitigation is improved, but hydraulic fluid flow efficiency deteriorates
Solution Approach 1:
The counter-balance valves incorporate dynamic pressure control where the opening pressure is not fixed but adjusted in real-time based on boom position, load conditions, and vibration levels. This allows the system to use higher restrictiveness only when and where vibration occurs, rather than maintaining high restrictiveness continuously, thus reducing energy loss while still achieving vibration mitigation.
Solution Approach 2:
The system changes the pressure parameter of the counter-balance valves dynamically. By adjusting the pilot pressure to the CBVs, the opening pressure threshold is modified according to operating conditions, enabling the valves to transition between different restrictive states - high restriction during vibration events and low restriction during normal operation, optimizing both vibration control and hydraulic efficiency.
3Object-affected harmful factors
If active vibration control systems are added to mitigate boom oscillation, then vibration reduction is improved, but device complexity and cost deteriorate
Solution Approach 1:
The system uses the existing hydraulic infrastructure (hydraulic cylinder, hydraulic fluid, counter-balance valves) to provide vibration control. The hydraulic cylinder itself acts as the actuator for vibration mitigation by adjusting piston area, and the counter-balance valves provide both safety and vibration control functions. This self-service approach eliminates the need for separate electric actuators, sensors, and control systems, reducing complexity while achieving active vibration control.
Solution Approach 2:
The invention uses hydraulic principles to achieve vibration control instead of electronic or mechanical systems. By manipulating hydraulic pressure and piston area in the existing cylinder, the system generates counteracting forces to reduce boom oscillation. This hydraulic-based approach leverages the existing fluid power system, avoiding the complexity of adding electric motors, sensors, and control electronics.
4Object-affected harmful factors
If hydraulic cylinder piston area is dynamically adjusted to counteract vibrations, then vibration mitigation is improved, but control system complexity deteriorates
Solution Approach 1:
The hydraulic cylinder is segmented into two independent sides, each with its own counter-balance valve and control mechanism. This allows independent adjustment of piston area on each side of the cylinder, enabling vibration control through differential area adjustment without requiring complex multi-actuator coordination systems.
Solution Approach 2:
The counter-balance valves serve as intermediaries between the controller and the hydraulic cylinder. By adjusting the opening pressure of the CBVs, the controller indirectly controls the effective piston area without directly actuating the cylinder. This intermediary approach simplifies control by using pressure modulation rather than direct mechanical or electronic actuation of the piston area.
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 reduces boom vibrations across a wide range of operating conditions with minimal sensors, maintaining safety and efficiency, and can be retrofitted to existing systems, improving performance and reliability by actively controlling vibrations without requiring electrical signals or additional mass on the boom.
Implementation Method 1
A hydraulic system with a pair of counter-balance valves and control valves that dynamically pressurize and depressurize chambers to counteract vibrations
Implementation Method 2
counter-balance valves that dynamically pressurize and depressurize chambers to counteract vibrations, while ensuring safety and preventing uncommanded movements
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 actuator (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 actuator, and a second chamber (118, 116) of the hydraulic actuator 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 first blocking valve prevents the fluctuating hydraulic fluid flow from opening the first counter-balance valve. The first blocking valve may drain leakage from the first counter-balance valve.