Thrust Washer Groove Pumping for Sparse Lubrication
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Solution Overview
Problem
Thrust washers fail due to excessive interface temperature caused by loss of lubrication, particularly in applications where lubrication is available only at the outer diameter, as existing designs fail to effectively pump lubricant into the interface, overcoming centrifugal force.
Innovation Solution
The use of improved groove features in thrust bearings made from thermoplastic, thermoset, metallic, or ceramic materials that pump lubricant from the outer diameter to the inner diameter, creating thin lubricant films and reducing friction and interface temperature, allowing for use in low lubrication conditions and aggressive speed and pressure applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional groove geometries are used, then the thrust washer structure is simple, but the ability to pump lubricant into the interface is insufficient, leading to loss of lubrication and excessive interface temperature
Solution Approach 1:
The groove is segmented into multiple functional zones: an inlet zone at the outer diameter to capture lubricant, a pumping zone with optimized curvature to generate hydrodynamic pressure, and an outlet zone to distribute lubricant across the interface. This segmentation allows each zone to perform its specific function efficiently, improving overall lubrication effectiveness without requiring overly complex geometries
Solution Approach 2:
The groove geometry parameters are optimized including the groove depth, width, curvature radius, and spiral angle. By carefully selecting these parameters, the groove generates sufficient hydrodynamic pressure to pump lubricant against centrifugal force while maintaining manufacturing feasibility and avoiding excessive complexity
2Productivity
If the thrust washer operates at high speed, then productivity is improved, but centrifugal force increases, making it difficult to pump lubricant into the interface
Solution Approach 1:
The groove design utilizes hydrodynamic principles to generate pressure through the relative motion between the thrust washer and the counterface. The curved groove geometry converts the rotational motion into hydraulic pressure that pumps lubricant inward against centrifugal force, enabling effective lubrication delivery even at high operational speeds
Solution Approach 2:
The groove geometry is designed to be dynamically effective across a range of speeds. The spiral or curved configuration ensures that as the thrust washer rotates, the groove continuously generates hydrodynamic pressure that adapts to the operating conditions, maintaining lubrication effectiveness from low to high speeds
3Reliability
If more lubricant is supplied to the interface, then lubrication effectiveness improves, but frictional drag and torque increase
Solution Approach 1:
The groove design delivers lubricant precisely where it is needed at the interface, creating a thin lubricant film in the high-stress contact zones. This localized lubrication approach provides sufficient protection against wear and overheating while minimizing the overall amount of lubricant in the system, thereby reducing frictional drag and energy loss
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
These designs effectively utilize lubricant, reducing torque and enabling operation in very low lubrication conditions, with improved hydrodynamic performance and reduced frictional drag, allowing for broader application ranges.
Implementation Method 1
The new groove features pump lubricant from the OD of the washer to the ID while providing hydrodynamic performance
Implementation Method 2
loss of lubrication available only at the OD of the bearing due to the inability of existing designs to effectively pump lubricant into the interface by overcoming centrifugal force
Implementation Method 3
improve the ability to form thin lubricant films. The features allow better film generation and thereby lower friction and interface temperature
Data Source
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 faces includes a plurality of recessed grooves extending at least partially between the inner edge and the outer edge and defining un-recessed lands between the recessed grooves. The plurality of recessed grooves include a transition region transitioning to the lands and a scoop region separated from the transition region by a stepped wall portion extending between the scoop region and the tapered region. The recessed grooves can include directional symmetric bi-directional grooves for use in systems with rotation in both directions.