Hydraulic Load Descent Control via Pilot Pressure Segmentation
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Solution Overview
Problem
Current control devices for load descent in working machines are complex and costly, leading to undesirable pressure increases on the cylinder during load lowering, which results in inefficient energy use and mechanical stress, and fail to provide precise control over load lowering speed, especially when loads consist of vehicles carrying people.
Innovation Solution
A control device comprising a directional control valve, a control valve, a shut-off valve, and one-way valves that allow precise modulation of pilot pressure and flow rate to control the descent of loads, ensuring safe and efficient operation by preventing uncontrolled drainage and cavitation, while allowing gravity-assisted lowering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex directional control valves are used to control pilot pressure for load descent, then precise control of load lowering speed is achieved, but device complexity and cost increase
Solution Approach 1:
The patent divides the control function into separate components: a simple directional control valve for flow direction and a separate control valve (5) for pilot pressure regulation. This segmentation allows each component to perform its function simply, avoiding the need for a single complex valve that combines multiple functions.
Solution Approach 2:
The patent introduces a control valve (5) as an intermediary component that specifically manages pilot pressure to the control valve (4). This intermediary component handles the complex pressure modulation task, allowing the directional control valve to remain simple while achieving precise load descent control through the mediator's pressure regulation.
2Measurement precision
If complex directional control valves are used to modulate pilot pressure for load descent control, then load lowering speed control is improved, but energy expenditure and mechanical stress on the cylinder increase
Solution Approach 1:
The patent extracts the pressure modulation function from the directional control valve and places it in a separate control valve (5) positioned in the pilot line. This allows the main hydraulic circuit to operate with minimal pressure loss while the pilot circuit handles pressure regulation independently, reducing overall energy expenditure during load descent.
Solution Approach 2:
The control valve (5) acts as an intermediary in the pilot line that regulates pressure without creating significant energy loss in the main hydraulic circuit. By placing this pressure modulation function in a dedicated component with appropriate sizing and positioning, the system achieves precise load control while minimizing energy dissipation through optimized flow paths.
3Measurement precision
If complex directional control valves are used for pilot pressure control, then load descent precision is improved, but mechanical stress on the cylinder increases
Solution Approach 1:
The patent segments the control system so that the directional control valve handles only flow direction with minimal pressure drop, while the control valve (5) in the pilot line handles pressure modulation. This segmentation prevents excessive pressure buildup in the main cylinder circuit, reducing mechanical stress while maintaining precise control through the separated pressure management function.
4Stability of the object's composition
If the control valve remains closed to support the load, then load stability is maintained, but the load cannot be lowered without additional pilot pressure supply
Solution Approach 1:
The control valve (5) in the pilot line acts as an intermediary that enables easy transition between load support and load lowering modes. By regulating pilot pressure independently, it allows the main control valve (4) to remain closed for stable support while providing a simple pressure signal path for controlled descent, improving operational ease without compromising stability.
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 precise and safe control of load descent speed, reducing energy expenditure and mechanical stress, and preventing cavitation, thereby ensuring smooth and controlled load lowering irrespective of the directional control valve's technical features.
Implementation Method 1
A hydraulic cylinder is designed to lift or lower the load by supplying working fluid under pressure to a first chamber or to a second chamber
Implementation Method 2
The control valve has the function of allowing the free supply of working fluid to the base plate side of the cylinder, and of controlling or blocking the drainage of working fluid from the base plate side of the cylinder
Implementation Method 3
Whenever possible, in order to save energy, the load is lowered by exploiting gravity
Data Source
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AI summary
A control device for the descent of a load, comprising: a first conduit (2), designed to connect a first chamber (C1) of a cylinder (C) with a directional control valve (D); a second conduit (3), designed to connect a second chamber (C2) of the cylinder (C) with the directional control valve (D); a control valve (4), disposed along the first conduit (2), which is designed to allow the flow of fluid from the directional control valve (D) toward the first chamber (C1) and to allow the flow of fluid from the first chamber (C1) toward the directional control valve (D) only if supplied with a pilot pressure that is greater than a minimum value; a shut-off valve (5), disposed along the second conduit (3), which is designed to take on a closed configuration, in which it prevents the flow of fluid along the second conduit (3), and an open condition, in which it enables the flow of fluid from the directional control valve (D) toward the second chamber (C2) only if the pressure present between the shut-off valve (5) and the directional control valve (D) exceeds a given minimum pressure; a pilot conduit (6), which connects the control valve (4) with the section of the second conduit (3) between the shut-off valve (5) and the directional control valve (D); a drainage conduit (7) which connects the section of the second conduit (3) between the shut-off valve (5) and the second chamber (C2) with a drain (T); a one-way valve (8), disposed along the drainage conduit, which prevents flow from the drain (T) toward the second conduit (3) and allows flow from the second conduit (3) toward the drain only if the pressure upstream of the one-way valve (8) exceeds a given minimum pressure; a choke (13), disposed in parallel with the shut-off valve (5).