Thrust Washer Groove Geometry for Hydrodynamic Lubrication
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Solution Overview
Problem
Thrust washers fail due to loss of lubrication and high interface temperature conditions, limiting their effectiveness in aggressive speed and pressure applications.
Innovation Solution
The design incorporates improved groove features that promote the formation and retention of thin lubricant films, reducing friction and interface temperature by using thermoplastic or thermoset materials with machining or plastic molding techniques, and featuring recessed grooves with specific geometric characteristics to support thrust forces and rotational speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional groove geometries are used, then the thrust washer can be manufactured with standard designs, but the lubricant film generation is insufficient leading to high friction and interface temperature
Solution Approach 1:
The thrust washer surface is segmented into multiple grooves and lands, dividing the lubrication function across multiple zones. Each groove acts as an independent lubricant reservoir and flow channel, while the lands between them generate hydrodynamic pressure. This segmentation improves lubrication effectiveness without requiring a single complex geometric feature.
Solution Approach 2:
The groove geometry is optimized with specific local characteristics including rounded bottoms, tapered sides, and varying depths across the thrust washer surface. These local quality variations create different flow patterns and pressure distributions in different zones, enhancing overall lubrication effectiveness while using relatively simple manufacturing techniques.
2Adaptability or versatility
If standard thrust washer designs are used, then manufacturing is simpler, but the washer cannot effectively operate in aggressive speed and pressure applications
Solution Approach 1:
The groove geometry is designed to dynamically adapt to operating conditions. As the thrust washer rotates under load, the grooves automatically regulate lubricant flow and pressure distribution based on the instantaneous speed and pressure conditions. This dynamic behavior enables the washer to adapt to aggressive applications without requiring multiple different designs for different operating regimes.
Solution Approach 2:
The groove dimensions including depth, width, and spacing are optimized as specific parameters to achieve desired performance in aggressive applications. By carefully controlling these geometric parameters during manufacturing, the thrust washer can be tailored for high-speed and high-pressure operations while maintaining manufacturability through standard machining or molding processes.
3Loss of energy
If conventional groove designs are used, then the friction and torque are higher, but the lubricant utilization is insufficient
Solution Approach 1:
The groove design leverages hydrodynamic principles where the rotating thrust washer pumps lubricant through the groove channels, generating hydrodynamic pressure in the lands between grooves. This hydraulic action creates a lifting film that separates the sliding surfaces, dramatically reducing friction and torque loss while efficiently utilizing the lubricant supply.
Solution Approach 2:
The groove geometry is designed to self-regulate lubricant distribution based on operating conditions. The tapered sides and rounded bottoms of the grooves create automatic flow control that directs lubricant to high-pressure zones where it is most needed, reducing energy loss without requiring external control mechanisms or excessive lubricant quantities.
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 solution enables thrust washers to operate at lower friction and torque, allowing them to be used in more aggressive speed and pressure applications while effectively utilizing very low lubrication conditions.
Implementation Method 1
grooves or partial grooves with the geometric features designed to promote a fluid flow under washer and generate/retain fluid film to support thrust forces
Implementation Method 2
The features allow better film generation and thereby lower friction and interface temperature
Data Source
Figure 1~2
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Figure 5~6
AI summary
A thrust washer includes an annular body with an aperture therein and having a first axial face and a second axial face, an outer diameter edge and an inner diameter edge extending between the first and second axial faces. At least one of the first and second axial or conical faces includes a plurality of recessed grooves extending at least partially between the inner edge and the outer edge and defining unrecessed lands between the recessed grooves. The plurality of recessed grooves defining an average groove width and the plurality of lands defining an average land width between the grooves, wherein a ratio of the groove width to the land width is in a range of 0.2 to 2. The plurality of recessed grooves include a convex lead in surface having a lead in radius.