Fixed Thrust Abutment With Staged Pads for Lubricant Film Continuity
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Solution Overview
Problem
The existing stop systems in turbochargers face challenges in maintaining a continuous lubricant film and preventing mechanical contact due to friction and impurities, which can lead to reduced performance and reliability under varying axial loads and operational conditions.
Innovation Solution
A fixed stop system with two series of pads, where the second series is set back from the first by a few micrometers, providing a greater hydraulic lift surface in case of failure of the first series, ensuring robustness and reliability by maintaining the lubricant film even under abnormal conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the hydraulic bearing surface is reduced to minimize sliding friction, then friction between bearings is reduced, but the ability to maintain a continuous lubricant film decreases
Solution Approach 1:
The bearing surface is segmented into multiple independent pads arranged in series along the axial direction. Each pad can independently maintain a lubricant film, so if one pad's film breaks due to impurities or load variations, other pads continue to provide hydrodynamic support, ensuring continuous lubrication and preventing metal-to-metal contact.
Solution Approach 2:
Multiple pads are arranged in series to provide redundant hydrodynamic support before mechanical contact can occur. This preemptive redundancy ensures that if the lubricant film on one pad breaks down, other pads are already in place to absorb the load and prevent direct contact between bearing surfaces.
2Device complexity
If a single thrust bearing is used to support axial load, then the structure is simple, but the system is vulnerable to damage from impurities or load variations
Solution Approach 1:
The single thrust bearing is segmented into multiple independent pads arranged in series. This segmentation allows the system to handle impurities and load variations more effectively, as each pad operates independently and can tolerate film breakdown without causing catastrophic failure of the entire bearing system.
Solution Approach 2:
Each pad is designed with specific local characteristics (dimensions, positioning, structural features) optimized for its role in the series. The pads can have varying sizes and positions to distribute load appropriately and maximize the probability that at least one pad maintains an intact lubricant film under varying operating conditions.
3Loss of energy
If the bearing surface is minimized to reduce friction, then sliding friction decreases, but the probability of mechanical contact due to film breakdown increases
Solution Approach 1:
The bearing surface is divided into multiple small pads rather than one large continuous surface. This segmentation reduces the probability that impurities or load variations will cause film breakdown across the entire surface, while still maintaining low overall friction through the hydrodynamic effect on each individual pad.
Solution Approach 2:
The system changes the parameter of bearing surface configuration from a single large surface to multiple smaller surfaces arranged in series. This parameter change maintains the low-friction hydrodynamic lubrication benefit while increasing the statistical probability that at least one pad will maintain an intact lubricant film under varying operating conditions.
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 system effectively reduces sliding friction and maintains the lubricant film, ensuring robustness and reliability by shifting the hydraulic lift to the second series of pads in case of wear or contamination, thereby preventing mechanical contact and maintaining performance across varying operational conditions.
Implementation Method 1
this lubricant film creates a force between the bearings that tends to move the rotating thrust bearing away from the fixed bearing by approximately twenty micrometers
Implementation Method 2
The structured surface of the bearing pads, featuring features such as shoulders and/or grooves, defines the hydraulic bearing surface between the opposing faces of the fixed thrust bearing and the rotating thrust bearing. During operation, these features create micro-reservoirs capable of receiving the lubricant, which spreads into a film under the force generated by the rotation of the rotating thrust bearing.
Implementation Method 3
This facilitates sliding friction between the bearings while minimizing mechanical friction between the surface of the bearing pads and the opposing surface of the rotating thrust bearing.
Data Source
Figure 1~3
AI summary
Fixed abutment of a system of fixed and rotary abutments intended for withstanding an axial load along the axis of a rotating shaft mounted in a guide bearing, particularly of a turbocharger, said fixed abutment being provided in the form of a flange bored with a through-opening allowing the rotating shaft to pass through, having, on its surface, runners with structured zones, said fixed abutment comprising at least two series of runners, a first series of runners (100) with structured zones present in a first ring on the surface of said flange, and a second series of runners (110) with structured zones present in a second ring, coaxial with the first ring on said surface of the flange, set back from said first series of runners in the longitudinal direction of the axis of said opening.