Cast Crankshaft Core for Mass Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing crankshaft manufacturing methods require additional machining and plug-pressing operations to prevent bay-to-bay pumping losses in high-RPM engine dry sump lubrication systems, limiting material removal and mass reduction.
Innovation Solution
A cast crankshaft core structure that eliminates the need for machining and plug installation by configuring a pair of end main bearing core segments with counterweight and pass-through core segments, creating a void region between intermediate main bearing journal core segments and counterweight core segments to remove all but a thin wall of material from the main bearing journals, blocking oil flow and enabling mass reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If machining holes in main journals and installing plugs is used to prevent bay-to-bay pumping losses, then oil flow between bays is blocked, but manufacturing complexity increases and mass reduction is limited
Solution Approach 1:
The core structure is designed and positioned within the mold cavity before the casting process begins. This preliminary placement allows the core to define the hollow main journals and block oil flow paths during the casting itself, eliminating the need for subsequent machining and plug installation operations. The core structure performs the oil flow blocking function during manufacturing rather than requiring post-processing.
Solution Approach 2:
The core structure removes material from the center of the main bearing journals during casting, creating hollow passages that reduce mass. The core itself is extracted from the final product after casting, leaving the desired hollow structure. This extraction approach allows for greater material removal compared to machining methods while maintaining structural integrity through the thin walls.
2Reliability
If machining and plug pressing operations are used to prevent oil flow through main bearing journals, then bay-to-bay pumping is prevented, but manufacturing time and complexity increase
Solution Approach 1:
The core structure is positioned within the mold cavity before casting, establishing the oil flow blockage and hollow journal structure in advance. This preliminary action integrates the oil flow control function into the primary manufacturing process rather than requiring separate post-processing steps, thereby reducing total manufacturing cycle time.
Solution Approach 2:
The invention combines multiple functions into the core structure: it defines the hollow main journals for mass reduction, blocks oil flow paths to prevent bay-to-bay pumping, and creates the thin wall structure. By merging these functions into a single casting operation with the core in place, the manufacturing process is simplified and accelerated compared to sequential machining and plug installation operations.
3Weight of moving object
If material is removed from main bearing journals to reduce mass, then crankshaft weight decreases, but structural strength may be compromised
Solution Approach 1:
The core structure creates hollow passages specifically in the main bearing journals where mass reduction is desired, while maintaining solid material distribution in other critical areas of the crankshaft. The thin walls of the hollow journals are strategically designed to provide sufficient strength for bearing support while removing unnecessary material from the journal centers, achieving local optimization of the strength-to-weight ratio.
Solution Approach 2:
The hollow main journals are formed with thin walls that act as flexible yet structurally sound shells. These thin walls provide the necessary strength to support main bearings while significantly reducing the mass of the journals compared to solid construction. The thin wall structure maintains structural integrity through optimal thickness design that balances mass reduction with strength requirements.
Data Source
AI summary
A core structure for a cast crankshaft is provided which eliminates the need to machine and install plugs in one or more of the main bearing lightening holes. This is achieved by configuring the core structure to take out all but a thin wall of material in the center of the main bearing journals.