Pilot-Relief Spool Valve for Safe Limited Hydraulic Flow
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Solution Overview
Problem
Existing hydraulic systems lack a simple and effective mechanism to ensure safety functionality, particularly in applications like cranes and hydraulic steering devices, by limiting fluid flow to prevent dangerous situations.
Innovation Solution
A hydraulic arrangement with a pilot pressure relief port connected to a return port via a shut-off valve, which opens after a predetermined spool stroke to limit fluid flow, and is remotely controlled by actuating means such as a solenoid, ensuring safe limited flow functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the shut-off valve is opened to limit flow for safety, then safety functionality is improved, but full flow capability is lost
Solution Approach 1:
The system dynamically switches between two flow modes (limited and full) based on operational requirements. The shut-off valve transitions from a static component to a dynamic control element that adapts the flow characteristics in real-time, allowing the system to optimize between safety and performance based on current working conditions
2Productivity
If the spool stroke is restricted to limit flow, then flow control is improved, but user comfort deteriorates due to abrupt pressure drops
Solution Approach 1:
The pilot pressure relief chamber acts as a cushioning buffer that gradually reduces pressure when the spool reaches its stroke limit. Instead of an abrupt pressure drop, the relief chamber absorbs the pressure change over time, smoothing the transition and maintaining user comfort while still enforcing flow limits
3Reliability
If a complex safety mechanism is added to hydraulic systems, then safety functionality is improved, but device complexity increases
Solution Approach 1:
The existing spool valve structure is enhanced with multi-functionality rather than adding separate safety components. The spool simultaneously performs flow control, position sensing, and safety limiting functions, while the pilot pressure relief chamber serves both pressure regulation and safety protection roles, reducing overall system complexity
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 solution provides a safe and controlled fluid flow mechanism, adapting to working conditions, enhancing user comfort and safety by preventing abrupt pressure drops and allowing full flow only when the shut-off valve is closed.
Implementation Method 1
The spool is actuated by a hydraulic pilot pressure in a pressure chamber. The pressure in the pressure chamber drives the spool in its lengthwise direction.
Implementation Method 2
the hydraulic fluid producing the pilot pressure in the pressure chamber is released to the return port, so that the pressure in the pressure chamber cannot further increase
Data Source
Figure 1~2
AI summary
A hydraulic arrangement (1) comprising a supply port (P), a return port (T), a working port arrangement (L, R), and a valve (2) controlling a supply of hydraulic fluid from the supply port (P) to the working port arrangement (L, R), wherein the valve (2) comprises a housing (4) and a spool (3) movable in lengthwise direction in the housing (4) and forming together with the housing (4) at least one flow path the resistance of which depends on the position of the spool (3) in the housing (4), and the spool (3) is actuated by a hydraulic pilot pressure (21, 22) in a pressure chamber (7, 8). In such a hydraulic arrangement a safety functionality should be achieved in a simple way. To this end the housing (4) comprises a pilot pressure relief port (20) connected to the return port (T) via a shut-off valve (10) and the spool (3) after a predetermined stroke (13, 14) opens a connection between the pressure chamber (7, 8) and the pilot pressure relief port (20).