Covered Thrust Relief Structure for Half Crankshaft Bearings
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Solution Overview
Problem
The existing half thrust bearings in internal combustion engines suffer from fatigue, such as cracks and peeling, due to impact loads applied during the connection of the crankshaft and transmission, which leads to premature wear in the thrust relief and bearing alloy layers.
Innovation Solution
A semi-annularly shaped half thrust bearing with a back metal layer made of Fe alloy and a bearing alloy layer, featuring thrust reliefs with a cover member made of the same bearing alloy, which absorbs impact loads and reduces stress on the bearing alloy layer, preventing fatigue by distributing the load across the back metal layer and cover member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the half thrust bearing is used by being fitted to a bearing seat with slightly larger inside diameter, then the half thrust bearing is slightly movable in circumferential direction for ease of installation, but impact load is applied to the circumferential end surfaces causing fatigue
Solution Approach 1:
A rubber cushion member is provided between the circumferential end surfaces of the half thrust bearing and the bearing seat. This cushion member absorbs impact loads that occur during operation, preventing direct transmission of impact forces to the half thrust bearing structure. The cushioning action resolves the contradiction by maintaining the movable fit for ease of installation while protecting against fatigue from impact loads.
2Adaptability or versatility
If the thrust relief is formed with constant length and depth, then misalignment of end surfaces is absorbed, but the bearing alloy layer adjacent to thrust relief is susceptible to fatigue
Solution Approach 1:
The rubber cushion member is positioned to absorb impact loads before they reach the thrust relief area and bearing alloy layer. This prevents fatigue in the bearing alloy layer adjacent to the thrust relief while maintaining the thrust relief's ability to absorb misalignment through its constant length and depth configuration.
Solution Approach 2:
The rubber cushion member acts as an intermediary between the half thrust bearing and the bearing seat, absorbing impact loads and preventing their direct transmission to vulnerable areas including the thrust relief and bearing alloy layer. This mediator resolves the contradiction by protecting the bearing structure while maintaining the thrust relief's misalignment absorption capability.
Data Source
AI summary
A half thrust bearing includes a back metal layer, a bearing alloy layer defining a slide surface, and two thrust relieves formed adjacent to both circumferential end surfaces of the half thrust bearing and each including a thrust relief surface. The back metal layer includes an exposed end face configuring at least a part of the circumferential end surface, an exposed slant surface configuring at least a part of the thrust relief surface, and a transition surface formed between the exposed end face and the exposed slant surface. The transition surface is covered with a cover member including a cover end surface configuring at least a part of the circumferential end surface and a cover slant surface configuring at least a part of the thrust relief surface.