Valve Actuator Split Thrust Bearing Design
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Solution Overview
Problem
Existing valve actuators suffer from deformation due to high loads applied during the operation of large butterfly valves, as the drive screw is subjected to compressive forces that can lead to bowing or other structural failures, reducing their service life.
Innovation Solution
The valve actuator design includes a rotatable, threaded drive screw with thrust bearings provided both at the insertion and distal end portions, distributing loads as tensile forces rather than compressive, thereby reducing the risk of deformation. This is achieved through the use of collars with thrust bearings and a distal end cover that houses additional thrust bearings, ensuring the drive screw can withstand significant operational forces without bowing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single locking collar with thrust bearings is used to support the drive screw, then the device complexity is reduced, but the drive screw deforms under high loads
Solution Approach 1:
The single locking collar is divided into two separate collars: a first locking collar at the insertion end and a second locking collar at the distal end. Each collar has its own thrust bearings, distributing the load support across two independent bearing systems rather than one overloaded system.
Solution Approach 2:
The load support is extended from a single-point support (one collar) to a distributed multi-point support system (two collars at opposite ends of the drive screw), effectively adding a dimensional aspect to the load distribution architecture.
2Device complexity
If the traveling nut is positioned far from the single locking collar, then the actuator design is simplified, but the drive screw bows under compressive loads
Solution Approach 1:
The single point of rotational support is segmented into two separate rotational support points (first and second locking collars), creating multiple stabilization points along the drive screw length to prevent bowing.
Solution Approach 2:
The second locking collar with thrust bearings acts as a counterbalancing support that offsets the destabilizing effect of the traveling nut's position, providing rotational stability that counteracts the bowing tendency caused by compressive loads.
3Force
If high closing forces are applied to the drive screw, then the valve performance is improved, but the drive screw deforms or fails
Solution Approach 1:
The thrust bearing support function is segmented across two separate bearing systems, allowing the high closing forces to be distributed and managed by two independent bearing assemblies rather than one overloaded bearing.
Solution Approach 2:
The second locking collar with thrust bearings serves as an intermediary rotational support that mediates the transmission of high closing forces, providing an additional load path that protects the drive screw from direct compressive deformation.
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
The configuration significantly enhances the ability of the valve actuator to withstand large operational forces, reducing the likelihood of deformation and extending the service life by distributing loads as tensile forces, which are less likely to cause structural damage compared to compressive forces.
Implementation Method 1
thrust bearings provided both at the insertion and distal end portions, distributing loads as tensile forces rather than compressive
Data Source
AI summary
A valve actuator includes a body having at least a first side and an interior. A rotatable, threaded drive screw extends into the body and projects out of the body first and second sides. The drive screw comprises an insertion portion and a distal end portion. A traveling nut is threadingly captured on the drive screw in the body interior. The traveling nut is held against rotation whereby it travels along the drive screw as the screw rotates. An actuator arm engages the nut and is configured to be urged between valve open and closed positions as the traveling nut travels along the drive screw. A first collar is attached to at least a portion of the drive screw insertion portion and has at least a bearing for rotatably engaging the body. A second collar is attached to at least a portion of the drive screw distal end portion and has at least a bearing for rotatably engaging the body.