Synchronizer device and synchronization method

A synchronizer device for a manual transmission, comprising

• a sliding sleeve which includes an internal toothing having a multitude of sliding sleeve teeth and is rotatable about a transmission axis (A),
• a clutch body of a speed change gear, the clutch body having an external toothing having a multitude of clutch body teeth for the internal toothing of the sliding sleeve to engage therein, and
• a synchronizer unit including a synchronizer ring which has an external toothing having a multitude of synchronizer ring teeth and is adapted to block an axial movement of the sliding sleeve,
• wherein the internal toothing of the sliding sleeve includes locking teeth each having an axial tooth end that is pointed on both sides in the circumferential direction and meshing teeth each having a blunt axial tooth end,
• wherein the blunt tooth ends of the meshing teeth include one single or a plurality of convex end faces, the single convex end face or one of the plurality of convex end faces each extending in the circumferential direction from a first root point adjacent to a tooth flank of the sliding sleeve tooth via an axially protruding apex portion as far as to a second root point, the second root point adjoining an opposite tooth flank of the tooth when there is one single convex end face and being a valley point of an indentation between neighboring convex end faces when there is a plurality of convex end faces, and an axial distance (a) between the apex portion and each of the root points amounting to a maximum of 18% of a tooth width (b) of the sliding sleeve tooth,
• wherein the single convex end face or the plurality of convex end faces each include an end face portion which extends perpendicularly to the transmission axis (A) or which has a tangent line extending perpendicularly to the transmission axis (A), and
• wherein locking tooth groups of a plurality of locking teeth that are directly adjacent to each other in the circumferential direction and meshing tooth groups of a plurality of meshing teeth that are directly adjacent to each other in the circumferential direction alternate in the circumferential direction.