Pressure Independent Control Valve With Everting Sleeve
Solution Overview
Problem
Current pressure independent control valves in HVAC systems face issues with membrane deterioration and debris collection due to rapid fluid flow, affecting valve operation.
Innovation Solution
The implementation of a pressure independent control valve design featuring an everting sleeve isolated from the main fluid flow, utilizing a piston and pilot valve system with a compression spring and set screw adjustment to control fluid flow through outlet apertures, ensuring the everting sleeve is protected from degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a membrane is used to control valve disk position in response to fluid pressure, then the valve can maintain constant pressure differential, but the membrane deteriorates due to rapid fluid flow containing debris
Solution Approach 1:
The patent removes the vulnerable membrane component from the system and replaces it with a piston-operated mechanism. The piston is directly actuated by fluid pressure on its face, eliminating the need for a membrane that could deteriorate from debris exposure. This extraction of the problematic membrane while retaining the pressure-responsive control function resolves the contradiction between reliability and debris exposure.
Solution Approach 2:
The patent introduces an intermediary piston mechanism between the fluid pressure source and the valve disk. Instead of fluid pressure acting directly on a membrane, the pressure acts on the piston face, which then transmits force through a stem to move the valve disk. This intermediary piston protects the control mechanism from direct exposure to harmful debris in the fluid flow.
2Ease of operation
If the everting sleeve is exposed to main fluid flow for operation, then the valve can control flow through outlet apertures, but the everting sleeve suffers degradation from debris and erosion
Solution Approach 1:
The patent segments the valve into distinct functional zones: a pilot valve section for control and a main valve section for flow regulation. The everting sleeve is positioned in the pilot valve section where it controls fluid flow to the piston, while the main fluid flow passes through separate outlet apertures in the body. This segmentation allows the everting sleeve to perform its control function without direct exposure to the harmful main fluid flow.
Solution Approach 2:
The patent uses fluid pressure as an intermediary to transmit control signals from the everting sleeve to the piston. The everting sleeve modulates control fluid flow, which then acts on the piston face to move the valve disk. This indirect control mechanism allows the everting sleeve to regulate main flow without being in direct contact with the harmful debris-containing fluid.
3Measurement precision
If a pilot valve system with compression spring is used to control the piston, then precise pressure differential control is achieved, but device complexity increases
Solution Approach 1:
The patent combines the pilot valve, compression spring, and piston control mechanisms into an integrated assembly within a single valve body. The pilot valve with its adjustable compression spring is merged with the main piston mechanism, allowing precise pressure differential control without requiring separate external control systems. This merging reduces overall system complexity while maintaining measurement precision.
Solution Approach 2:
The piston serves multiple functions: it acts as a diaphragm replacement for pressure sensing, a valve stem for disk actuation, and a seal element for the outlet apertures. The compression spring provides both force application and adjustable setpoint functionality. This multi-functionality reduces the number of separate components needed, achieving precise control without proportionally increasing system complexity.
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 maintains a constant pressure differential across the piping system while preventing the everting sleeve from exposure to the main fluid flow, enhancing the valve's operational reliability and longevity.
Implementation Method 1
a compression spring positioned to bias the pilot valve, which in turn can be forced into greater or lesser compression against the pilot valve diaphragm by adjusting a set screw
Implementation Method 2
The pilot valve is controlled in part with relatively high pressure fluid ported from the high pressure port in an associated piping system and relatively low pressure fluid ported from a lower pressure port in an associated piping system, applied to a pilot valve diaphragm
Implementation Method 3
The pilot valve is operable to pressurize an operating chamber bounded by an everting sleeve, which in turn acts on the piston disposed in a tube, to translate it relative to outlet apertures in the tube
Data Source
AI summary
A flow control valve including a main valve and a pilot valve for controlling a piston of the main valve. The pilot valve is controlled in part with relatively high pressure fluid ported from a high pressure port and relatively low pressure fluid ported from a low pressure port.