Vehicular Seat Reclining Lock Strength via Axial Protrusion

The invention adds a protrusion that extends in the axial direction from the cylinder portion, creating a three-dimensional structure that increases the effective wall thickness at the tooth root without increasing the outer diameter. This dimensional extension allows the tooth root to be supported from both the radial direction and the axial direction, effectively increasing the load-bearing cross-section and maintaining lock strength despite the reduced overall size of the apparatus.

The invention applies local reinforcement by adding the protrusion specifically at the tooth root region where the bending moment is highest. This localized structural enhancement concentrates material where it is most needed for strength, rather than uniformly increasing the wall thickness throughout. The protrusion creates a local increase in section modulus at the critical tooth root, allowing the teeth to maintain high strength even with fewer teeth overall in the reduced-diameter design.