Two-Stroke Engine Transfer Passages Spiral Sand Core

The patent combines multiple separate sand cores into a single common sand core that forms all transfer passages simultaneously. This merging approach eliminates the need for separate positioning of individual cores, thereby resolving the contradiction by maintaining manufacturing simplicity while achieving high positioning precision through integrated core design.

The patent employs spiral and curved configurations for the transfer passages instead of straight or angular designs. This curvilinear approach improves scavenging efficiency by creating favorable flow patterns and pressure distributions, while the continuous curved geometry can be formed from a single sand core, thereby managing complexity through geometric elegance rather than mechanical complexity.

The patent merges multiple transfer passage functions into a single integrated sand core structure. This common core simultaneously forms all transfer passages with precise relative positioning, achieving good flow distribution through optimized passage geometry while dramatically simplifying manufacturing by eliminating the need for multiple separate core components and their associated positioning fixtures.