Electrohydraulic Valve Damping via Segmented Pilot Control
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Solution Overview
Problem
Electrohydraulic pressure-reducing relieving valves in fluid power systems exhibit dynamic complexity and poor dynamic response, leading to instability and inefficiency.
Innovation Solution
A two-stage pilot operated electrohydraulic pressure reducing-relieving valve with a linear electromagnetic actuator, a compliant spring coupling, and a common pressure rail with fine mesh filtration, which balances dynamic elements and reduces operational envelope for improved robustness and damping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrohydraulic pressure-reducing relieving valves are used, then the system is economical and commercially available, but the valve exhibits poor dynamic response and dynamic stability
Solution Approach 1:
The valve is divided into two independent stages: a pilot stage with an electromagnetic actuator and a main stage with a spool valve. The pilot stage controls the main stage, allowing independent optimization of each stage's dynamic characteristics. This segmentation enables the electromagnetic actuator to respond quickly while the main valve provides stable pressure control.
Solution Approach 2:
The pilot assembly acts as an intermediary between the electromagnetic actuator and the main valve spool. It translates small electromagnetic forces into larger hydraulic forces through pressure amplification, improving both response speed and control precision without requiring the main actuator to be oversized.
2Stability of the object's composition
If high pressure fluid is used for damping, then the stiffness of hydraulic fluid increases due to entrained air removal, but the operational envelope of the pilot subsystem must be reduced
Solution Approach 1:
The system uses a fine mesh filter to remove entrained air from the hydraulic fluid, changing the fluid's compressibility characteristics. This increases fluid stiffness and improves damping effectiveness, while the pilot subsystem's operational envelope is managed through controlled pressure ranges.
3Strength
If a rigid transfer rod is used to couple the armature to the pilot assembly, then the mechanical connection is strong, but force and motion disturbances are transmitted to the armature assembly
Solution Approach 1:
A flexible coupling mechanism replaces the rigid transfer rod, allowing the armature to be operatively coupled to the pilot assembly while isolating it from force and motion disturbances. This flexible connection maintains mechanical strength while filtering out harmful vibrations and shocks.
4Power
If the valve operates with large pressure differentials, then the valve can handle high power applications, but parasitic energy waste increases when the valve is idle
Solution Approach 1:
The pilot-operated design allows the main valve to remain partially closed or in a neutral position during idle conditions, minimizing energy waste. The pilot stage uses minimal energy to maintain control pressure, while the main valve only opens when necessary for full power operation.
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 fast, robust, and reliable fluid power valve with individually tunable damping characteristics, minimizing parasitic energy waste and enhancing dynamic stability and response.
Implementation Method 1
electrohydraulic pilot operated pressure reducing/relieving valves that incorporate linear electro-magnetic actuators as a means to convert electrical current to mechanical force
Implementation Method 2
the pilot assembly amplifies the electromotive force to create a hydramotive force that is significantly higher in magnitude
Implementation Method 3
operative coupling between the armature and the pilot subassembly is achieved not through a rigid transfer rod, but through a compliant spring
Implementation Method 4
a common pressure rail is derived from the high-pressure fluid via a fine mesh filter. This filtered high pressure rail is employed in the dynamic control of the fluid power elements
Implementation Method 5
a network of dashpots and the control port of the pilot assembly
Data Source
AI summary
Disclosed herein are methods and systems of robust electrohydraulic pressure control with distributed damping. The system includes a two-stage pilot operated electrohydraulic pressure reducing-relieving valve have a valve body with a high-pressure port, a low-pressure port, and a variable working pressure port. A valve spool is disposed within the valve body to direct oil flow into and out of a working volume, and a pilot subassembly is also disposed within the valve body to generate a pilot pressure and create a hydraulic motive force to operate the valve spool. A linear electromagnetic actuator is operatively coupled to the pilot subsystem to generate an electromotive force to operate the pilot assembly. The system further includes a fluid path that restrictively communicates a common fluid pressure to a volume of fluid defined by a position of the linear electromagnetic actuator.