Rollerized Cranktrain Bedplate Structural Rigidity
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Solution Overview
Problem
Conventional reciprocating engines with rollerized cranktrains face challenges in maintaining structural rigidity and strength due to the use of thicker roller bearings, which weaken the cylinder block and main bearing caps, and suffer from differential thermal expansion between materials, necessitating a solution that enhances rigidity, minimizes part counts, and accounts for thermal expansion.
Innovation Solution
A bedplate with a peripheral support structure, cross-members, and rolling element bearings made of similar material to the cylinder block, secured with bolts, which replaces main caps and provides structural support to the crankshaft, while incorporating lubricant galleries and oil drains for efficient lubrication and drainage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If roller element bearings are used to replace plain bearings in the cranktrain, then friction and wear are reduced improving engine efficiency and durability, but the bearing thickness increases causing material removal from the cylinder block and bearing caps which weakens their structural strength
Solution Approach 1:
The invention merges the bearing cap and cylinder block into a single integrated bedplate structure. The bedplate includes bearing support portions that directly support the roller element bearings without requiring separate bearing caps. This integration eliminates the need to remove material from separate caps while maintaining structural strength, as the bedplate is designed as a unified component with optimized material distribution.
Solution Approach 2:
The bedplate is segmented into multiple functional regions including bearing support portions, cross-members, and peripheral support structures. Each segment is optimized for its specific function while contributing to the overall structural integrity. The bearing support portions are specifically designed to accommodate the thicker roller element bearings while the cross-members and peripheral structures provide the necessary structural reinforcement.
2Use of energy by moving object
If roller element bearings with greater thickness are installed, then reduced friction and improved efficiency are achieved, but more material must be removed from the cylinder block and bearing caps weakening their structural integrity
Solution Approach 1:
By combining the bearing support function with the structural support function into a single bedplate, the invention eliminates the need for material removal from separate bearing caps. The bedplate is designed with bearing support portions that have the necessary thickness to accommodate roller element bearings while maintaining overall structural integrity through integrated design.
Solution Approach 2:
The bedplate can be constructed using composite materials or material gradients that provide both the necessary thickness for roller element bearing support and the structural strength required for engine loads. Different regions of the bedplate can use different material properties optimized for their specific functions.
3Strength
If separate main caps and ladderframe structures are used to support the crankshaft, then structural rigidity and load capacity are improved, but the number of parts and assembly complexity increase
Solution Approach 1:
The invention combines the functions of main caps, ladderframe, and bearing supports into a single integrated bedplate structure. The bedplate includes peripheral support structures and cross-members that provide the necessary rigidity and load capacity previously achieved through multiple separate components, thereby reducing part count and assembly complexity while maintaining structural performance.
4Reliability
If main caps made of different material than the cylinder block are used, then bearing support functionality is improved, but differential thermal expansion occurs between components
Solution Approach 1:
The bedplate is designed as a unified structure made from the same material as the cylinder block, ensuring homogeneous thermal expansion characteristics throughout the assembly. This eliminates differential thermal expansion between bearing caps and cylinder blocks, as both components are now part of the same homogenous bedplate structure.
Data Source
AI summary
Featured is a bedplate for a reciprocating engine having a rollerized cranktrain. Such a bedplate includes a peripheral support structure having sides and ends, a plurality of cross members that extend between the sides of the peripheral support structure, and a plurality of rolling element bearings. Each of the plurality of cross members includes a bearing support portion, the bearing support portion being configured so as to receive and retain therein a portion of one of the rolling element bearings. Also, the portion of the rolling element bearing is such that when the bedplate is secured to a cylinder block of the reciprocating engine, the bearing support portion rotatably supports a crankshaft of the reciprocating engine. Also featured is a reciprocating engine having such a bedplate.