Engine Cylinder Bore Wall Thin Section for Displacement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge in downsizing a motorcycle engine is exacerbated by the limited mounting space, where enlarging the cylinder bore wall affects the formation of bolt through-holes, making it difficult to reduce engine size while maintaining displacement.
Innovation Solution
The engine design incorporates a cylinder body with a circular inner surface, a cylinder head, and a through bolt system, featuring projections and thin wall portions in the coolant storing groove that allow for increased displacement without enlarging the external form, enabling the engine to be downsized by positioning the bolt through-holes without moving them outward.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the cylinder bore wall is enlarged to increase engine displacement, then the engine displacement is increased, but the engine size (external form) increases
Solution Approach 1:
The invention applies local quality by creating a thin wall portion at a specific location on the cylinder bore wall that faces the projection. This localized thinning allows the cylinder bore wall to be enlarged for increased displacement while the thin wall portion compensates by projecting inward, preventing the external dimensions from increasing. The local modification enables displacement increase without overall size increase.
Solution Approach 2:
The invention utilizes dimensional compensation by creating a projection from the cylinder body outer wall into the coolant storing groove, and compensating with a thin wall portion in the cylinder bore wall. This creates a balance where the outward projection and inward thinning offset each other, allowing the cylinder bore to be enlarged without increasing the external form dimensions.
2Quantity of substance
If the bolt through-hole position is moved outward to accommodate larger cylinder bore, then the cylinder body and cylinder head size increase, but the engine displacement is increased
Solution Approach 1:
The invention fixes the bolt through-hole position in the cylinder body outer wall without moving it outward. Instead, it creates a thin wall portion locally on the cylinder bore wall to accommodate the enlarged displacement. This local quality change allows displacement increase while maintaining the original external dimensions and bolt hole positions.
3Quantity of substance
If the cylinder bore wall is enlarged, then the engine displacement is increased, but the mounting space requirement increases
Solution Approach 1:
The invention enables displacement increase through local modifications (thin wall portion and projection) rather than overall enlargement. This allows the engine to achieve larger displacement while maintaining the same external form and mounting space requirements, as the thin wall portion compensates for the enlarged bore internally.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
In a water-cooled, one-cylinder engine formed with a water jacket 21 along the whole circumference between a cylinder bore wall 27 and a cylinder body outer wall 28, a bolt through-hole 24 for inserting a through bolt 5 which couples a cylinder body 3 with a cylinder head 4 is formed in the cylinder body outer wall 28. Parts of areas around the bolt through-holes 24 are extruded into a water jacket 21 and make projections 32A to 32D. Areas on the cylinder bore wall 27 that face the projections 32A to 32D are cut in an axial direction to make thin wall portions 33A to 33D. Thereby, it is possible to downsize an engine without lowering the engine capacity.