Pilot-Control Electromagnetic Valve for Low-Loss High-Flow Switching
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Solution Overview
Problem
Existing pilot-operated directional-control valves face challenges in controlling large volumetric flows with low flow losses, as they require large opening cross-sections and strokes for the main piston, which are hindered by flow and friction forces, especially when mechanically actuated by a spring.
Innovation Solution
The solution involves a valve design where the position of the main piston is adjusted by a pilot piston, actuated by a solenoid device, which signals fluid pressure to control the main piston's position, allowing for linear adjustment and compensation of flow and friction forces, thereby reducing the need for large solenoid systems or hydraulic pilot operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If large opening cross-sections and large strokes of the main piston are used to control large volumetric flows with low flow losses, then flow losses are reduced, but flow and friction forces increase which counteract the switching movement
Solution Approach 1:
The valve system is divided into two independent controllable paths: a main volumetric flow path controlled by the main piston and a pilot volumetric flow path controlled by the pilot piston. This segmentation allows the main piston to handle large flows with minimal resistance while the pilot piston manages the control function separately, eliminating the conflict between large opening cross-sections and high switching forces.
Solution Approach 2:
The pilot piston acts as an intermediary between the solenoid device and the main piston. Instead of the solenoid directly actuating the main piston against large flow and friction forces, the pilot piston mediates by controlling pilot flow that indirectly influences the main piston position, thereby reducing the direct force requirements on the solenoid system.
2Ease of operation
If the solenoid system is dimensioned large to meet stroke and force demands, then switching capability is improved, but device complexity and dimensions increase
Solution Approach 1:
The control function is segmented between the pilot piston (actuated by solenoid) and the main piston. The solenoid only needs to dimension for the small pilot piston movements, not for the full main piston stroke and force requirements, dramatically reducing solenoid system size while maintaining overall valve switching capability.
Solution Approach 2:
The pilot piston serves as a force amplifier and movement translator between the small solenoid actuation and the larger main piston movements. This intermediary mechanism allows a small solenoid system to control a much larger main valve, reducing device complexity and dimensions.
3Device complexity
If mechanical actuation by spring is used to reset the piston, then simplicity is improved, but the spring force rating is too small compared to frictional force for resetting
Solution Approach 1:
The pilot-operated hydraulic system provides the resetting force for the main piston through fluid pressure control. When the pilot piston moves, it controls pilot flow that creates pressure differential to reset the main piston, overcoming friction forces that would be too large for a simple spring mechanism to handle alone.
Solution Approach 2:
The pilot hydraulic system acts as an intermediary force generation mechanism between the simple spring return and the main piston resetting requirement. It amplifies the small spring force into sufficient resetting force through hydraulic pressure multiplication, maintaining simplicity while overcoming friction.
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
This design achieves improved control quality with low pressure losses while preventing leakages, allowing for a highly dynamic proportional throttle valve with reduced dimensions and smaller strokes of the main piston.
Implementation Method 1
the pilot piston can be actuated by the force (Fmagnet) of the solenoid device
Implementation Method 2
a fluid pressure acting on the main piston is signalled via a fluid connection into a pilot chamber with the pilot piston which, when the solenoid device is not actuated, holds the main piston in its closed position preventing the main volumetric flow
Implementation Method 3
the pilot piston moves into a position in which the fluid pressure, decoupled from the pressure supply via the main piston, in the pilot chamber decreases until the main piston reaches an open position
Implementation Method 4
the pilot piston being substantially pressure-balanced taking into account a frictional force (Ffriction)
Data Source
AI summary
The disclosure relates to a valve, comprising a main plunger for controlling a main volume flow and comprising a pilot-control plunger for controlling a pilot-control volume flow. The main and pilot-control plungers are longitudinally moveably guided in a valve housing and the pilot-control plunger can be actuated by a magnetic device. The position of the main plunger can be adjusted by the pilot-control plunger in that a fluid pressure at the main plunger is communicated, via a fluid connection, into the pilot control chamber containing the pilot-control piston, which keeps the main plunger in its closed position blocking the main volume flow when the magnetic device is not actuated. When the magnetic device is actuated, the pilot-control plunger moves into a position in which the fluid pressure falls in the pilot-control chamber until the main plunger moves into an open position controlling the main volume flow.