Bearing Cap Composite Frame for Thermal Expansion Control
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Solution Overview
Problem
Bearing caps made of light alloys in internal combustion engines experience increased bearing clearance due to thermal expansion differences with crankshafts, leading to hammering sounds, and existing solutions that use iron-based members to mitigate this issue complicate the cylinder block manufacturing process and increase weight.
Innovation Solution
A bearing cap configuration where an iron-based frame is embedded within a light-alloy part, featuring a circular-arc-shaped arch section and bolt through holes, allows the light-alloy part to thermally expand and shift radially inward, thereby reducing vertical bearing clearance without altering the cylinder block configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If bearing cap is made of light alloy, then weight is reduced, but bearing clearance increases due to thermal expansion difference with crankshaft
Solution Approach 1:
The bearing cap is constructed as a composite structure with an iron-based alloy material embedded within the light alloy material. The iron-based material has a thermal expansion coefficient similar to the crankshaft, while the light alloy provides weight reduction. This composite configuration allows the bearing cap to maintain low weight while suppressing bearing clearance increase through the thermal expansion characteristics of the iron-based component.
2Reliability
If iron-based member is inserted into cylinder block and bearing cap, then bearing clearance increase is suppressed, but weight increases and manufacturing process becomes complicated
Solution Approach 1:
The iron-based member is merged with the light alloy bearing cap by embedding it within the light alloy material during the casting process. This integration allows the bearing cap to be manufactured as a single composite component, eliminating the need for separate assembly steps and reducing manufacturing complexity while maintaining the bearing clearance stability benefits of the iron-based material.
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
This configuration effectively suppresses bearing clearance expansion and reduces weight by allowing the light-alloy part to thermally expand and shift inward, minimizing hammering sounds and maintaining a simple cylinder block design.
Implementation Method 1
when temperature rises, the span between the bolts of the bulkhead, bolts which fix the bearing cap to the bulkhead, increases and the light-alloy part thermally expands
Data Source
Figure 1~2
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Figure 5
AI summary
A bearing cap (1) is attached to a bulkhead (22) of a cylinder block (21) made of a light metal through a pair of bolts (24). The bearing cap (1) has a frame (2) made of an iron-based metal and a cast light-alloy part (3). The frame (2) has a pair of pillar parts (9) through which the bolts (24) extend and a circular-arc-shaped arch section (10). At high temperatures, the span of the pair of the bolts (24) increases due to thermal expansion of the light-alloy material, and the pair of the pillar parts (9) expand. This causes the middle part of the arch section (10) to shift upward, thereby suppressing an increase in bearing clearance.