Half Thrust Bearing Groove Layout for Seizure-Resistant Lubrication
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Solution Overview
Problem
Existing half thrust bearings for crankshafts in internal combustion engines face challenges in preventing seizure due to high temperatures of the oil film between the slide surface and the thrust collar, especially during prolonged vibration of the crankshaft.
Innovation Solution
A semi-annularly shaped half thrust bearing with a slide surface featuring at least two radially extending oil grooves, pad surfaces with constant axial thickness, first and second inclined surfaces with gradually decreasing axial thickness, circumferential grooves on the inclined surfaces, and oil drain grooves on the pad surfaces to effectively manage oil flow and temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the crankshaft diameter is reduced to save weight, then the weight of the internal combustion engine is reduced, but the rigidity of the crankshaft decreases causing increased vibration and easier bending
Solution Approach 1:
The slide surface is segmented into multiple pad portions separated by oil grooves, creating independent load-bearing zones that can better accommodate crankshaft vibration and bending without direct contact, thus protecting against seizure despite reduced rigidity
2Duration of action of moving object
If the crankshaft vibrates for a long time, then the operating duration increases, but the oil temperature becomes excessively high causing seizure of the half thrust bearing
Solution Approach 1:
Hot oil is extracted from the pad portions through dedicated oil drain grooves that channel the high-temperature oil away from the friction surfaces, preventing heat accumulation and seizure during prolonged operation
Solution Approach 2:
The system discards the heated oil through drain grooves and replaces it with fresh lubricating oil from the oil supply, continuously removing heat and maintaining effective lubrication during extended vibration periods
3Reliability
If oil grooves are provided on the slide surface, then oil supply is improved preventing seizure, but the structural complexity of the bearing increases
Solution Approach 1:
The lubrication system is segmented into multiple functional zones with different groove types (radial oil grooves for supply, circumferential grooves for distribution, drain grooves for removal), each performing a specific function that collectively ensures reliable seizure prevention
Solution Approach 2:
The oil groove structure serves multiple functions simultaneously: supplying oil to pad portions, distributing oil circumferentially, draining hot oil, and maintaining oil pressure, thereby achieving reliable seizure prevention through an integrated multi-functional design
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 described configuration effectively prevents seizure by maintaining a high-pressure oil film and efficiently draining high-temperature oil, thereby reducing the risk of direct contact between the slide surface and the thrust collar.
Implementation Method 1
a high-pressure oil film is formed in a clearance between the inclined surface and the thrust collar surface during the running of the internal combustion engine
Implementation Method 2
a plurality of oil drain grooves extending side by side so as to intersect the circumferential direction and the radial direction are formed on the pad surface
Data Source
AI summary
A half thrust bearing includes a slide surface which includes: at least two oil grooves extending in a radial direction; a plurality of pad surfaces located on both sides of each oil groove in a circumferential direction; and at least two first inclined surfaces each formed between the oil groove and the pad surface on a front side of the oil groove in a rotation direction of a crankshaft. A plurality of circumferential grooves are formed in succession in the radial direction on the first inclined surface. A plurality of oil drain grooves extends side by side to intersect the circumferential direction and the radial direction on the pad surface. A plurality of flat portions are formed each between the adjacent oil drain grooves. Each oil drain groove is open at a radially outer end and/or a radially inner end of the pad surface.