Adjustable Actuator Stop for Butterfly Valves
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Solution Overview
Problem
Existing valve actuators for large butterfly valves face challenges with adjustable stop mechanisms that require disassembly, are messy, time-consuming, and prone to structural failure due to high closing forces, and existing solutions either fail to provide adequate support or increase the actuator's cost and complexity.
Innovation Solution
A valve actuator design featuring a rotatable drive screw with an external thread, an internally threaded crosshead, and an axially adjustable sleeve that transfers loads to the drive screw, allowing for external adjustment without disassembly, and a locking mechanism using a removable pin for secure positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a screw projects through the actuator body to provide an adjustable stop, then the stop position can be adjusted externally, but the high closing forces cause failure of the body wall or require an overly thick wall
Solution Approach 1:
A sleeve is introduced as an intermediary component between the drive screw and the actuator body. The sleeve receives the closing forces from the traveling nut and transfers them to the drive screw, preventing these forces from being transmitted to the actuator body wall. This allows the body wall to remain thin while still providing external adjustability through the sleeve's position on the screw.
2Strength
If adjustable stop nuts are located in the interior of the actuator body, then the structure can support high forces, but the body must be opened for adjustments making the operation messy and time-consuming
Solution Approach 1:
The sleeve serves as an external intermediary that provides the same force support function as internal stop nuts without requiring access to the interior. By positioning the sleeve at different locations along the drive screw, the closing forces are intercepted externally, eliminating the need to open the body for adjustments.
Solution Approach 2:
The adjustment function is separated from the force support function. The sleeve provides force support externally, while the traveling nut handles the closing forces internally. This segmentation allows the sleeve to be positioned externally for easy adjustment while the internal components remain protected within the sealed body.
3Ease of operation
If a setscrew is used to hold the sleeve and drive shaft in position, then external adjustment is possible, but the setscrew cannot provide sufficient support against high closing forces
Solution Approach 1:
The sleeve acts as a force-distributing intermediary that replaces the setscrew's force-bearing function. Instead of relying on a small setscrew to withstand high closing forces, the sleeve's larger surface area and structural design allow it to distribute and withstand these forces while still permitting external adjustment through its position on the drive screw.
4Device complexity
If the setscrew transfers the load directly to the fixed support portion of the housing, then the connection is simple, but a substantially thickened housing wall is required
Solution Approach 1:
The sleeve serves as a force-transfer intermediary that redirects the load path. Instead of the setscrew transferring load directly to the housing wall (requiring thickening), the sleeve transfers the load to the drive screw, which is designed to handle these forces. This maintains connection simplicity while eliminating the need for thickened housing walls.
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
Enables precise and efficient adjustment of the valve's closed position without opening the actuator body, effectively managing high closing forces without structural modifications, thus improving operational efficiency and reducing maintenance complexity and costs.
Implementation Method 1
a load created by the member pressing against the abutment surface of the sleeve is transferred from the sleeve to the drive screw as a tensile load
Implementation Method 2
The drive screw has an external thread over at least a portion of its length. An internally threaded member, sometimes referred to as a crosshead, is captured on the drive screw
Data Source
AI summary
A valve actuator including a body, a rotatable drive screw having an external thread over at least a portion of its length and extending through the body and projecting out at least one side of the body. An internally threaded member is captured on the drive screw on the interior of the body, the member being held against rotation during rotation of the drive screw, so as to cause the member to travel along a length of the drive screw as the drive screw is rotated in both a first and second rotational direction. At least one sleeve having an abutment surface engagable by the member upon a sufficient rotation of the drive screw in one of the two directions. The sleeve surrounds the drive screw and may be axially adjustable relative to the drive screw from the exterior of the body. The sleeve may be threadingly engaged with the drive screw and slidingly carried in the body such that a load created by the threaded member pressing against the abutment surface of the sleeve is transferred from the sleeve to the drive screw as a tensile load.