Split Sliding Bearing Thickness Profile for Crankshaft Coaxiality
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Solution Overview
Problem
The existing crankshaft support structures face issues with coaxiality and smooth lubrication due to elastic bending deformation in cylinder blocks during engine assembly, leading to potential steps between split bearings and impaired oil film formation.
Innovation Solution
A sliding bearing design featuring a pair of semi-annular split bearings with varying thicknesses, where the thickness of one bearing decreases towards its end surfaces to match the thickness of the other, preventing step formation and ensuring smooth oil flow and proper oil film formation between the crankshaft and bearings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a pair of split bearings with different thicknesses is used to correct bearing holding portion deviation, then coaxiality of bearings is improved, but steps are formed on the inner circumferential side which hinder smooth oil flow and oil film formation
Solution Approach 1:
The bearing thickness is made non-uniform in a controlled manner, with the thicker portion strategically positioned to compensate for bearing holding portion deviation while the thinner portion avoids creating harmful steps. This local variation in thickness achieves coaxiality correction without the adverse effects of uniform thickness differences.
Solution Approach 2:
The bearing is designed with asymmetric thickness distribution, where one bearing in the pair has a different thickness profile than the other. This asymmetric design allows the bearings to compensate for misalignment while maintaining smooth inner circumferential surfaces that facilitate proper oil flow and film formation.
2Object-generated harmful factors
If uniform thickness split bearings are used, then smooth oil flow is maintained, but bearing coaxiality deteriorates when bearing holding portions have position deviations
Solution Approach 1:
Instead of uniform thickness, the bearing employs localized thickness variation where only specific regions differ in thickness. This allows the bearing to adapt to bearing holding portion position deviations while maintaining smooth surfaces in critical oil flow regions, thus preserving both coaxiality and lubrication performance.
3Manufacturing precision
If the thickness of split bearings is varied to correct bearing holding portion deviation, then coaxiality is enhanced, but the complexity of bearing design and manufacturing increases
Solution Approach 1:
The bearing design utilizes controlled parameter variation in thickness as a straightforward method to achieve coaxiality. By systematically varying the thickness parameter in specific regions rather than introducing complex structural changes, the solution enhances precision while keeping manufacturing relatively simple.
Data Source
AI summary
A sliding bearing that is disposed in a cylinder block and supports a journal portion of a crankshaft, including: a semi-annular first split bearing having a first circumferential end surface; and a semi-annular second split bearing having a second circumferential end surface. The first and second circumferential end surfaces contact each other, the first split bearing has a same outer diameter as an outer diameter of the second split bearing, the second split bearing has a thickness at a second circumferentially central position that is greater than a thickness of the first split bearing at a first circumferentially central position, the thickness of the first split bearing is decreased from the first circumferentially central position toward the first circumferential end surface, the thickness of the second split bearing is decreased from the second circumferentially central position toward the second circumferential end surface.