Curved Tapered Polygon Insert for Lower-Pressure Driveshaft Torque Transfer
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Solution Overview
Problem
Existing torque transmission methods, such as threaded connections and traditional tapered polygon inserts with flat surfaces, face issues with high contact pressure and sensitivity to clearances, leading to stress concentrations and potential loosening during operations like well drilling, where thermal expansion and vibration can cause the connection to become loose.
Innovation Solution
A tapered cylindrical polygon insert with curved inner surfaces is used, which provides a larger effective contact width and reduces contact pressure, allowing for more efficient torque transmission and increased durability by distributing the torque reaction force more evenly across the surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If traditional tapered polygon inserts with flat surfaces are used, then torque transmission is achieved, but high contact pressure and stress concentrations occur
Solution Approach 1:
The patent applies curvature by replacing the traditional flat contact surfaces with cylindrical curved surfaces. The insert features a cylindrical outer surface that contacts the housing and a cylindrical inner surface that contacts the driveshaft, creating curved contact areas instead of flat surfaces. This curvature distributes the contact pressure more evenly across the interface, reducing stress concentrations while maintaining effective torque transmission capability
2Force
If threaded connections or traditional splines are used, then torque transmission is achieved, but the connection becomes sensitive to clearances and may loosen during operation
Solution Approach 1:
The cylindrical curved surfaces create a conformal contact geometry between the insert, housing, and driveshaft. This curved interface is less sensitive to clearance variations compared to flat surfaces or threaded connections, as the curvature allows for better accommodation of manufacturing tolerances and thermal expansion, maintaining reliable torque transmission without loosening during operation
Solution Approach 2:
The patent changes the geometric parameters of the contact surfaces from flat to cylindrical curved surfaces. This parameter change in surface geometry fundamentally alters the contact mechanics, distributing loads more evenly and reducing sensitivity to clearance changes, thereby improving connection stability under varying operational conditions including thermal expansion and vibration
3Area of stationary object
If tapered polygon inserts are used, then clearances are taken up, but significant stress concentrations are introduced into components
Solution Approach 1:
The cylindrical curved contact surfaces provide a larger effective contact area compared to traditional flat surfaces, while the curved geometry naturally distributes the applied loads more uniformly. This eliminates the stress concentrations that occur at the edges of flat surfaces or at discrete spline teeth, as the continuous curved surface allows for smooth load distribution across the entire contact interface
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 tapered cylindrical polygon insert effectively reduces contact pressure and enhances torque transmission efficiency, enabling it to handle higher loads and tolerate more wear before damage, while maintaining a secure connection even with reduced retaining forces, thus reducing the need for frequent replacements.
Implementation Method 1
tools such as drilling tools often require torque to be transmitted from a rotating housing to a driveshaft
Data Source
AI summary
Transmitting torque from a housing to a drive shaft by configuring contact surfaces between a housing and shaft to increase the transmission of torque. Tools such as drilling tools often require torque to be transmitted from a rotating housing to a driveshaft. This is often accomplished through threaded connections or splines. A threaded connection can be used to transmit torque by allowing two pieces to be securely joined by rotating and tightening to a specified torque. A splined connection can also be used to transmit torque, providing sufficient clearance for one member to slidingly receive the other without rotating and torqueing. A tapered polygon may be used to transmit torque that by virtue of tapering can take up clearances between the torque carrying components. As such, the tapered polygon does not introduce significant stress concentrations into the components.