Rotary Shear Valve Port Geometry for Low-Flow Pressure Control
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Solution Overview
Problem
Existing directional control valves in hydraulic systems lack efficient flow metering and pressure control, particularly at low flow rates, due to limited angular control over the open area during rotor rotation, leading to difficulties in precise manipulation of fluid flow.
Innovation Solution
The design incorporates a rotor with notches and flow path diversions at the perimeter of outlet ports, allowing for selective coupling of ports as the rotor rotates, facilitating linear pressure decrease and improved flow metering by increasing the open area as the rotor rotates, enabling precise control of fluid flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional rotor without notches is used, then the structure is simple, but the flow metering precision and pressure control are insufficient
Solution Approach 1:
The rotor outlet port perimeter is segmented into multiple sections including circular arcs and triangular notches. Each segment controls fluid flow at different rotation angles, enabling precise flow metering through progressive opening and closing of flow paths as the rotor rotates.
Solution Approach 2:
Different portions of the rotor outlet port perimeter are given different geometries (circular arcs for smooth flow, triangular notches for controlled closing). This local differentiation allows specific regions to perform specific functions: circular portions maintain flow while triangular portions provide linear pressure decrease during rotation.
2Ease of operation
If the rotor rotates to change port coupling, then the flow direction control is improved, but the pressure control particularly at low flow rates deteriorates
Solution Approach 1:
The rotor design enables dynamic control of the open area during rotation. As the rotor rotates between positions, the triangular notches progressively open or close, creating a linear decrease in pressure that provides dynamic pressure control throughout the rotation range, especially at low flow rates.
Solution Approach 2:
The geometric parameters of the outlet port (open area, flow path cross-section) are changed continuously during rotor rotation. The triangular notch geometry specifically provides a linear parameter change that translates rotation angle into predictable pressure and flow rate changes, improving pressure control precision.
3Productivity
If the open area is increased during rotor rotation, then the flow metering is improved, but the pressure drop increases
Solution Approach 1:
The triangular notches are positioned and sized to provide partial opening during rotation. Rather than fully opening the port, the notches provide a controlled, progressive increase in open area that achieves sufficient flow metering while limiting the maximum pressure drop by controlling the rate and extent of opening.
Data Source
AI summary
A rotor for a directional control valve includes a rotor body defining a sealing surface, a circumferential side surface, and a stem that receives a rotational input to rotate the rotor about an axis. A first opening is formed in the sealing surface and defines a first perimeter. The first opening is positioned to move along a rotation path as the rotor body rotates and has a first notch that extends from the first perimeter toward a centerline of the rotor body that is perpendicular to the axis and along the rotation path. A second opening is formed in the sealing surface and defines a second perimeter. The second opening is positioned to move along the rotation path as the rotor body rotates and has a second notch that extends from the second perimeter toward the centerline of the rotor body and along the rotation path.