Flush Valve Tilting Pilot Stem High Pressure Reliability
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Solution Overview
Problem
Conventional flush valves experience unreliable and inconsistent flush cycles under high inlet pressure, pilot valve wear, and non-uniform pressure issues due to side entry inlets, leading to reduced valve life and inconsistent flush volumes.
Innovation Solution
The flush valve design includes a main valve assembly with a pilot valve system that uses a guide tube and support abutment to prevent tilting, a rolling diaphragm for reduced friction, and an asymmetrical baffle to equalize pressure, along with dual flow throttling assemblies for consistent flow control, and an elastomeric seal for easy replacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional pilot valve system is used under high inlet pressure, then the valve structure is simple, but the flush initiation becomes unreliable and inconsistent due to the pilot valve being clamped closed tightly
Solution Approach 1:
The pilot valve assembly is segmented into a pilot valve body, pilot valve member, and stem that can tilt relative to each other. This segmentation allows the stem to tilt independently under high pressure while the pilot valve body remains stable, enabling reliable flush initiation without requiring a completely complex redesign of the entire valve system.
Solution Approach 2:
The stem is designed to be tiltable relative to the pilot valve body, creating a dynamic structure that adapts to pressure conditions. Under high inlet pressure, the stem can tilt to maintain pilot valve opening despite the clamping force, whereas a fixed rigid structure would fail to open reliably.
2Productivity
If the actuator tilts the pilot valve stem only slightly with a short rapid movement, then the operation is quick and efficient, but the pilot valve may fail to open due to inertia
Solution Approach 1:
The tiltable stem design allows for a larger effective movement range during actuation. The stem can tilt significantly relative to the pilot valve body, converting a short rapid actuator movement into a sufficient displacement to overcome pilot valve inertia and ensure reliable opening, while maintaining quick actuation response.
3Ease of manufacture
If a side entry inlet is used, then the valve structure is compact and easy to install, but non-uniform pressure causes inconsistent flush volume and side loading that reduces valve life
Solution Approach 1:
An asymmetrical baffle is introduced in the inlet passage to compensate for the inherent asymmetry of the side entry inlet. The baffle is positioned and dimensioned asymmetrically to create a more uniform pressure distribution across the main valve seat, eliminating inconsistent flush volume while maintaining the compact side entry configuration.
4Device complexity
If a rigid plastic poppet contacts a fixed elastomeric seating area in the full open position, then the valve structure is simple, but wear results from repeated operation making replacement and repair difficult
Solution Approach 1:
The pilot valve assembly is segmented into replaceable components including the pilot valve member with integrated seal. This segmentation allows the worn pilot valve member to be easily removed and replaced without replacing the entire pilot valve body or main valve assembly, significantly improving ease of repair while maintaining structural simplicity.
5Productivity
If a flow throttling structure is incorporated to regulate flow, then the flush volume can be controlled, but the flow continuously decreases as the main valve closes which is not desirable
Solution Approach 1:
The flow throttling is achieved through a restricted orifice in the diaphragm that provides localized flow regulation. This localized restriction maintains a relatively uniform flow rate during the initial flush portion by controlling the refill rate to the control chamber, preventing the continuous flow decrease that would result from uniform throttling throughout the valve closure process.
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
Ensures reliable and consistent flushing operations at high pressures, reduces wear, maintains uniform flow rates, and extends valve life while minimizing side loading and manufacturing costs.
Implementation Method 1
Inlet pressure in a control chamber normally holds the main valve member closed against the main valve seat
Implementation Method 2
When the stem is pivoted or tilted by the actuator, the pilot valve opens to exhaust the control chamber to the outlet of the flush valve. Inlet pressure moves the valve member from the closed position to an open position
Implementation Method 3
Water gradually flows into the control chamber through a restricted orifice, moving the diaphragm and main valve member back toward the closed position. After a measured volume of flow, the main valve closes
Data Source
AI summary
Tilting of a main valve assembly under high inlet pressure conditions is prevented by supporting the main valve assembly with housing rib engaging a skirt on the main valve guide tube. Pilot valve opening results from contact of an enlargement on the pilot valve stem with the push rod as the pilot valve begins its upward movement. An off center baffle compensates for the pressure pattern resulting from the side entry inlet. Throttling structure provided by a skirt on the guide tube cooperating with a shoulder in the outlet passage provides a desirable large flush flow. The inlet and handle openings in the valve body include bosses adjacent thereto an internal to the housing.