Half Thrust Bearing Structure for Crankshaft Impact Fatigue

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The existing half thrust bearings in internal combustion engines experience fatigue, such as cracks and peeling, due to impact loads when the crankshaft connects with a transmission, leading to premature wear in the thrust relief and bearing alloy layer.

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 bearing alloy layer extension portion that covers the transition surface, reducing the impact load on the bearing alloy layer and distributing it to the back metal layer, which is less prone to deformation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If the half thrust bearing is disposed to receive axial force of the crankshaft, then the axial force can be borne, but impact force is simultaneously applied to the proximity of the circumferential end surfaces, causing fatigue (cracks and/or peeling) in the thrust relief or bearing alloy layer

Engineering Contradiction:

Improveaxial force bearing capabilityVSAvoidfatigue resistance of thrust relief and bearing alloy layer

Core Design Contradiction:

ForceVSReliability

Solution Approach 1:

The bearing alloy layer is segmented into a slide surface portion and an extension portion that extends onto the circumferential end surface. This segmentation allows the extension portion to independently absorb impact forces, protecting the main bearing alloy layer from fatigue damage while maintaining axial force bearing capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The extension portion of the bearing alloy layer is positioned in advance on the circumferential end surface to act as a cushioning element. When impact forces occur during crankshaft connection with transmission, this extension portion absorbs the shock before it can reach the main bearing alloy layer, preventing fatigue cracks and peeling.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Adaptability or versatility

If the thrust relief is formed with constant length and depth, then misalignment of end surfaces can be absorbed, but the structure becomes rigid and susceptible to impact damage

Engineering Contradiction:

Improvemisalignment absorption capabilityVSAvoidresistance to impact load

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The bearing alloy layer is given different properties in different locations: the slide surface portion provides low friction for axial force bearing, while the extension portion on the circumferential end surface provides impact absorption. This local differentiation allows the structure to simultaneously absorb misalignment and resist impact loads.

Inventive Principle:

Principle #3Local quality

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 solution effectively reduces the occurrence of fatigue in the bearing alloy layer by elastically deforming the extension portion of the bearing alloy layer to absorb impact loads, thereby minimizing the propagation of stress to the thrust relief and slide surface areas.

Implementation Method 1

the extension portion of the bearing alloy layer is formed on the adjacent portion of the circumferential end surface to the thrust relief, so that this portion receives the impact load and is then elastically deformed

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Implementation Method 2

lubrication oil is fed from an oil gallery in a cylinder block wall into a lubrication oil groove formed along an inner peripheral surface of the main bearing through a through-hole in a wall of the main bearing

Methodology Applied

Scientific EffectLubrication: Lubrication

Data Source

PatentUS11035408B2Half thrust bearing for crankshaft of internal combustion engine

Publication Date: 2021.06.15 DAIDO METAL CO LTD

AI summary

A half thrust bearing for a crankshaft includes a back metal layer defining a first surface and a second surface, and a bearing alloy layer on the first surface to form a slide surface, and thrust relieves formed adjacent to both circumferential end surfaces and having a thrust relief surface consisting of the bearing alloy layer. Each circumferential end surface of the back metal layer includes an exposed end surface adjacent to the second surface, and a transition surface adjacent to the first surface. The bearing alloy layer further includes an extension portion covering the transition surface and having extension end surface adjacent to the exposed end surface, the extension end surface and the exposed end surface extending at least partly in the same plane.