Stepped Regulating Piston Geometry for Hydraulic Flow Force Compensation
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Solution Overview
Problem
Existing devices for regulating pistons in hydraulic valves face inefficiencies in flow force compensation, leading to undesirable pressure drops and movement towards closed positions due to flow forces, which affect the preset pressure supply to hydraulic consumers.
Innovation Solution
The design incorporates a step function change of shape on the regulating piston with subdivided flow contact surfaces, creating a fluid space that generates a counterforce to flow forces, optimizing force introduction and maintaining the preset pressure by ensuring the piston remains open.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple control edge geometry is used in the regulating piston, then the device structure is simple, but flow forces cause pressure drops and unwanted piston movement towards closed positions
Solution Approach 1:
The control edge geometry is segmented into multiple steps (first control edge, second control edge, third control edge) instead of a single continuous surface. Each step creates a distinct flow contact surface area, allowing the fluid to act at multiple locations to generate compensating forces that counteract flow-induced pressure drops and stabilize piston position.
Solution Approach 2:
Different sections of the control edge are given different geometric properties (varying step heights and positions). The first, second, and third control edges are positioned at different locations along the piston, creating localized flow contact surfaces with specific areas optimized for generating compensating forces at different stages of piston movement.
2Reliability
If the regulating piston moves towards closed position due to flow forces, then the flow force compensation is insufficient, but adding complex compensation mechanisms increases device complexity
Solution Approach 1:
The control edge geometry is designed to dynamically interact with the fluid flow during piston movement. As the piston moves, different flow contact surfaces are exposed to the fluid at different times, creating dynamic compensating forces that adapt to the instantaneous flow conditions and piston position, providing continuous flow force compensation without additional active components.
Solution Approach 2:
The fluid flow that initially causes harmful pressure drops and unwanted piston movement is redirected to act on the stepped control edge surfaces. This same fluid flow generates lifting forces on the flow contact surfaces that counterbalance the harmful flow forces, converting the harmful kinetic energy of the fluid into a beneficial compensating force.
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 solution effectively compensates for flow forces, maintaining the preset pressure supply to hydraulic consumers by generating a counterforce that pulls the piston into an open position, thus preventing blocking and ensuring consistent fluid flow.
Implementation Method 1
The fluid acting on the flow contact surface then causes an optimized introduction of force onto the regulating piston. As a result of the control edge following a step function and the change of shape also following a step function, a fluid space is created in the area. In that fluid space the fluid can flow to act on the flow contact surface and flow past the control edge. According to the force formula F=P×A, a counterforce to the flow force is generated during operation of the device
Data Source
AI summary
A device includes a regulating piston (12) guided longitudinally movably in a housing (10) and interacting with a control edge (56), at a pressure supply port (P) that supplies a utility port (A) in regulating positions of the regulating piston (12) with fluid. The pressure can be preset via a fluid connection, pulling the regulating piston towards a closed position blocking this fluid connection due to occurring flow forces. The regulating piston (12) has a change of shape (60) from its general outer basic shape in the area of the control edge (56) of the housing (10) for a flow force compensation. A flow contact surface for fluid is provided causing a compensating force acting against the flow force to be introduced into the regulating piston (12), which flow force pulls the regulating piston (12) into an open position opposite from the blocked position. The change of shape (60) also follows a step function, the function graph of which has at least one step more than the number of steps required to form the control edge (56).