Pilot-Operated Proportional Valve for Low-Loss High-Flow Control
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Solution Overview
Problem
Existing proportional valves face challenges with large opening cross-sections and strokes due to high friction and flow losses, especially when mechanically actuated by springs, requiring large solenoid systems or hydraulic pilot controls.
Innovation Solution
A valve design utilizing a pull-type actuating solenoid and a pilot piston mechanism, where the pilot piston balances forces to achieve a normally open variant with a linear valve characteristic, allowing for small solenoid dimensions and reduced opening cross-sections, enabling precise control with low pressure losses and minimal leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If large opening cross-sections are used to control high volumetric flows, then flow losses are reduced, but the stroke of the main piston increases and friction forces increase
Solution Approach 1:
The valve is divided into a main valve for controlling high volumetric flows and a pilot valve for controlling the pilot volumetric flow. The pilot valve with its own piston can be actuated by a solenoid device to control the main valve, enabling segmentation of control functions and reducing the stroke requirements of the main piston.
Solution Approach 2:
A pilot control mechanism is introduced as an intermediary between the solenoid device and the main piston. The pilot piston, when actuated, controls the fluid pressure acting on the main piston, enabling indirect control and reducing the direct force and stroke requirements on the main piston.
2Device complexity
If spring actuation is used to overcome friction forces, then mechanical actuation is simple, but the spring force may be too small compared to frictional force for resetting the piston
Solution Approach 1:
The pilot control acts as an intermediary that uses fluid pressure to amplify the force available for moving the main piston. The pilot piston, when actuated by the solenoid device, controls pressure differential across the main piston, enabling the main piston to overcome friction forces effectively without requiring excessively large spring forces.
Solution Approach 2:
Hydraulic principles are applied where pilot control fluid pressure acts on the main piston to enable movement. The fluid pressure generated through the pilot control system provides the necessary force to overcome friction and move the main piston, supplementing or replacing mechanical spring actuation.
3Reliability
If solenoid system is dimensioned large to meet stroke and force requirements, then valve performance is improved, but device size and complexity increase
Solution Approach 1:
The control system is segmented into a pilot control stage and a main valve stage. The solenoid device only needs to actuate the small pilot piston, requiring minimal force and stroke. The pilot piston then controls the main piston through fluid pressure amplification, enabling a small solenoid to control a large valve effectively.
Solution Approach 2:
The pilot control mechanism serves as a force amplifier intermediary. A small force applied to the pilot piston by the solenoid device is amplified through the pilot control mechanism to generate sufficient force on the main piston, enabling a compact solenoid system to control a large valve.
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 design achieves highly dynamic proportional control with reduced friction and pressure losses, ensuring efficient operation and precise adjustment of the main piston position, even at high volumetric flows.
Implementation Method 1
a pilot piston for actuating a pilot volumetric flow, the main piston and pilot piston being guided in a valve housing in a longitudinally movable manner and it being possible to actuate the pilot piston by means of a solenoid device
Implementation Method 2
The position of the main piston (10) can be adjusted by means of the pilot piston (12), by signalling a fluid pressure acting on the main piston (10) via a fluid connection (18) into a pilot chamber (20) with the pilot piston (12)
Implementation Method 3
when a pilot control is open, fluid passes from one of the two ports, which can be actuated by the main piston, via a cross-sectional restriction in the main piston and the pilot control to the third port, which can be actuated by the pilot piston, and whereby, due to the associated pressure drop, the main piston moves into a control position
Data Source
AI summary
The disclosure relates to a valve, comprising a main piston for actuating a main volumetric flow and a pilot piston for actuating a pilot volumetric flow. The main piston and the pilot piston are guided in a valve housing in a longitudinally movable manner, and the pilot piston can be actuated using a magnetic device. The position of the main piston can be set using the pilot piston in that a fluid pressure acting on the main piston is signalled via a fluidic connection into a pilot chamber comprising the pilot piston which keeps the main piston in the closed position thereof, said closed position cutting of the main volumetric flow.