Boom Bleed-Down Hydraulics for Safe Emergency Retraction
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Solution Overview
Problem
Conventional construction vehicles lack systems to ensure the boom remains within a safe operational range during lowering or retraction, especially when primary power is lost, leading to potential instability and safety risks for operators.
Innovation Solution
A hydraulic system with a backup battery power supply and solenoid bleed valves, allowing operators to control boom retraction within a predefined safety envelope, even when stranded at elevated positions, by channeling fluid flows between boom lift and extend actuators to maintain stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional failsafe modes are used to lower the boom during emergencies, then the operator can be lowered from the work platform, but the boom may move outside the safety envelope causing vehicle instability or tipping
Solution Approach 1:
The control system continuously monitors boom position and automatically adjusts the lowering rate to maintain the boom within the safety envelope. Sensors detect boom angle and extension position, and the controller modulates hydraulic flow to prevent the vehicle from becoming unstable during emergency lowering operations.
Solution Approach 2:
The system dynamically adjusts the boom lowering rate based on real-time position feedback. The lowering speed is not constant but varies to keep the boom tip within the predefined safety envelope, allowing faster lowering when safe and slower lowering when approaching stability limits.
2Reliability
If counterbalanced relief valves are used for failsafe mode, then hydraulic pressure can be relieved, but the valves are inaccessible to operators stranded at elevated positions
Solution Approach 1:
The system provides self-service emergency lowering capability through automated control. The operator simply activates the failsafe mode from the work platform, and the system automatically manages the entire lowering process including hydraulic pressure relief and boom retraction, eliminating the need for manual valve operation at ground level.
Solution Approach 2:
The manual mechanical valve operation is replaced with an automated electro-hydraulic control system. The control system electronically manages the relief valves and hydraulic actuators, substituting the need for direct mechanical access to ground-level components with remote electronic control from the elevated work platform.
3Device complexity
If existing hydraulic and electrical systems are relied upon for failsafe modes, then system integration is maintained, but damage to these systems impairs or loses the failsafe modes
Solution Approach 1:
The system incorporates redundant hydraulic circuits and backup control pathways designed beforehand to compensate for potential failures. If primary hydraulic lines or electrical components are damaged, the redundant systems automatically activate to maintain failsafe functionality, cushioning against the impact of component failure.
Solution Approach 2:
The control system can operate in multiple modes by changing operational parameters. When primary systems are damaged, the system transitions to alternative operating modes with adjusted hydraulic flow rates and pressure parameters, allowing failsafe functionality to be maintained despite component damage through parameter adaptation.
4Loss of time
If the boom is lowered quickly during emergencies, then operator rescue time is reduced, but the boom may exit the safety envelope causing vehicle instability
Solution Approach 1:
The lowering process is dynamically controlled with variable speed. The system starts with faster lowering when the boom is in safe positions and automatically reduces speed when approaching the safety envelope boundaries, optimizing the balance between rescue time and vehicle stability throughout the entire lowering sequence.
Solution Approach 2:
Real-time feedback from position sensors enables the control system to continuously adjust the lowering rate. The system monitors boom angle and extension position and modulates the hydraulic flow accordingly, accelerating lowering when safe and decelerating when approaching stability limits, achieving optimal rescue efficiency without compromising safety.
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
Enables safe and controlled boom retraction within a safety envelope, even in emergency situations without primary power, ensuring operator safety and system robustness against hydraulic and electrical failures.
Implementation Method 1
solenoid bleed valves, allowing operators to control boom retraction
Implementation Method 2
hydraulic system with a backup battery power supply and solenoid bleed valves
Implementation Method 3
backup battery power supply
Data Source
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AI summary
A hydraulic system for controlling bleed down and retraction of a boom within a safety envelope includes a backup battery power supply (506), and at least a first boom lift hydraulic cylinder (302) configured to raise and lower the boom. The first boom lift hydraulic cylinder includes a solenoid bleed valve (318) electrically connected to the backup battery power supply. An input device of the bleed valve is controllable by the operator to initiate bleed down and retraction of the boom from an elevated position. Also disclosed is a construction machine with a boom; a hydraulic system for controlling bleed down and retraction of the boom, a first boom extend actuator configured to receive a first flow of fluid from a first boom lift actuator in response to opening of the bleed valve, wherein when the first flow of fluid is received by the first boom extend actuator, the second boom extend actuator operates to retract the boom. Also disclosed is a method for controlling bleed down and retraction of a boom within a safety envelope, wherein a first flow of fluid from a first boom lift actuator and second flow of fluid from a second boom lift actuator are received and combined within a manifold and then selectively provided to a third actuator. The third actuator is configured to extend and retract the boom, wherein when the combined flow of fluid is provided to the third actuator, the third actuator retracts the boom within a safety envelope while the boom is being lowered.