Friction Bearing Segmented Gap Oil Distribution
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Solution Overview
Problem
Conventional friction bearings for crankshafts in internal combustion engines face issues with restricted lubricating oil flow, leading to heat build-up and increased friction loss due to limited oil ingress at entry points and between the groove and sliding surface.
Innovation Solution
A friction-bearing assembly with a second bearing gap, at least 10% wider than the first gap, positioned adjacent to the oil supply, allows lubricating oil to flow from the second gap into the first gap, improving oil distribution across the sliding surface, and the inner surface of the friction bearing can be inclined up to 30° relative to the shaft axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional friction bearing with a single bearing gap is used, then the structure is simple, but the lubricating oil flow is restricted leading to heat build-up and increased friction loss
Solution Approach 1:
The bearing gap is segmented into two distinct gaps: a first bearing gap adjacent to the oil supply and a second bearing gap at the end adjacent to the groove. This segmentation allows oil to flow through the first gap and then distribute into the second gap, ensuring complete encirclement of the shaft and improving lubrication efficiency without requiring complex additional components.
Solution Approach 2:
The two bearing gaps have different local characteristics optimized for their specific functions. The first gap is positioned for optimal oil reception from the supply, while the second gap is positioned to ensure complete oil distribution around the shaft circumference. Each gap's geometry and position are locally optimized to address specific lubrication needs at different locations within the bearing.
2Reliability
If the bearing gap is made wider to improve oil flow, then lubrication improves, but the clearance between bearing and shaft increases reducing support precision
Solution Approach 1:
The bearing clearance is segmented into two distinct gaps with different functions. The first gap provides the necessary clearance for oil flow reception, while the second gap ensures complete oil distribution. This segmentation allows each gap to be optimized for its specific function without compromising overall precision.
Solution Approach 2:
The solution transitions from a single radial clearance dimension to a two-dimensional oil flow path involving both radial and axial dimensions. Oil flows axially through the first gap and then radially through the second gap, utilizing multiple dimensions to achieve both adequate oil ingress and precise shaft support.
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
Enhances lubrication efficiency and reliability by ensuring consistent oil penetration across the sliding surface, reducing friction and heat build-up, thereby improving the durability of the friction bearing and the engine.
Implementation Method 1
the second bearing gap positioned at one of the first and second end, adjacent the first bearing gap and located in-between a lubricating oil supply and the first bearing gap such that the first bearing gap is supplied with lubricating oil through the second bearing gap
Implementation Method 2
to allow ingress of lubricating oil between the rotating shaft and the sliding surface to reduce friction
Implementation Method 3
to allow for heat expansion of the rotating shaft
Data Source
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AI summary
A friction-bearing assembly is disclosed which comprises a friction bearing and a shaft, the friction-bearing assembly includes a first bearing gap defined between the sliding surface of the friction bearing and the outer surface of the shaft, and a second bearing gap defined between the inside surface of the friction bearing and the outer surface of the shaft, the second bearing gap being at least 10% wider relative to the first bearing gap, to a maximum of 1 mm. The second bearing gap is positioned adjacent the first bearing gap and located in-between a lubricating oil supply and the first bearing gap such that the first bearing gap is supplied with lubricating oil through the second bearing gap.