Clip-Fastened Raceway for Variable Compression Ratio Engine
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Solution Overview
Problem
Existing methods for fastening raceways to the toothed wheel in variable compression ratio engines, such as electron beam welding and other welding techniques, face issues with thermal deformation, fatigue resistance, and compatibility with high carbon steel, leading to operational problems and inefficiencies.
Innovation Solution
A clip-fastened raceway system that eliminates the need for welding by mounting onto a fully finished toothed wheel, allowing for the use of conventional machining processes, is dismountable, and can be made from different materials with unique surface treatments, ensuring robustness and maintaining the wheel's diameter under varying loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If welding methods (electron beam welding or other welding techniques) are used to fasten raceways to the toothed wheel, then the raceways can be securely attached, but thermal deformation occurs and fatigue resistance is insufficient
Solution Approach 1:
The fastening system is divided into separate components: the toothed wheel with integrated hooks and the raceway with clips. This segmentation allows each component to be optimized independently - the toothed wheel can be machined to precise tolerances while the raceway can be attached through simple clipping without thermal stress, eliminating the welding process entirely while maintaining secure attachment and fatigue resistance
Solution Approach 2:
Hooks and clips serve as intermediary elements that bridge the toothed wheel and raceway. These intermediaries provide a mechanical fastening solution that avoids direct welding between the raceway and wheel, thereby preventing thermal deformation while ensuring secure attachment and long-lasting operation under varying loads
2Strength
If welding is used to attach raceways, then secure attachment is achieved, but thermal deformation alters the wheel's dimensions and mechanical characteristics
Solution Approach 1:
The harmful thermal process of welding is extracted from the fastening system. Instead of using heat-based attachment, the invention employs cold mechanical fastening through clips and hooks, allowing the toothed wheel to be fully finished to precise tolerances before assembly without any subsequent thermal deformation that would alter its dimensions or mechanical characteristics
3Stability of the object's composition
If raceways are made by machining the member bodies, then rigidity is significantly reinforced, but usual manufacturing methods like hob or grinding wheel cannot be used
Solution Approach 1:
The manufacturing process is segmented into two independent stages: first, the toothed wheel is fully finished using conventional machining methods (hob, grinding wheel) to achieve precise tooth geometry; second, the raceway is attached separately via clips. This segmentation removes the conflict between rigidity requirements and manufacturing flexibility, allowing both high precision machining and ease of manufacture to be achieved
4Manufacturing precision
If precision electro-chemical machining is used to finish teeth and raceways, then precision on the order of several microns is achieved, but the process is complex and time-consuming
Solution Approach 1:
The complex precision electro-chemical machining process is extracted and replaced with simpler conventional machining for the toothed wheel, followed by rapid clip attachment for the raceway. This eliminates the need for time-consuming electro-chemical processes while still achieving sufficient precision through traditional machining methods, significantly reducing manufacturing cycle time
Data Source
AI summary
A clip-fastened raceway for a variable compression ratio engine includes: at least one curved segment whose outer surface cooperates with a raceway housed in the transmission member or in the control member of the variable compression ratio engine and whose inner surface is maintained in contact with a curved outer surface housed in the toothed wheel of the engine; at least one clip, housed in at least one of the ends of the curved segment and fastened to one or the other of the ends of the curved outer surface housed in the toothed wheel and hooking onto a hook or protrusion which the wheel includes in the vicinity of the end of its curved outer surface, the hook or protrusion being complementary to that of the clip so as to be able to cooperate with the latter.