Gear having a helical toothing

A gear (1), which is made in one piece out of plastic, comprising:

• an axis of rotation (R),
• an external toothing (10) arranged about the axis of rotation,
• a concentrically arranged receiving opening (40),
• an intermediate portion (30) arranged between the external toothing (10) and the receiving opening (40),
• a reinforcing structure arranged in the intermediate portion (30) having a plurality of openings (32, 33), and reinforcing ribs (34, 35) disposed between the openings, characterized by the following additional features:
• the external toothing (10) is designed as a helical toothing with a helix angle (W) to the axis of rotation (R),
• at least some of the openings (32, 33) follow at least approximately the helix angle (W) of the helical toothing with an opening angle (V),
• characterized in that the teeth (12) of the external toothing (10) have, viewed in the axial direction, an edge-side tooth portion (7) which transitions from the helical toothing having the angle (W) to the spur toothing having the helix angle 0.

A gear (1), which is made in one piece out of plastic, comprising:

• an axis of rotation (R),
• an external toothing (10) arranged about the axis of rotation,
• a concentrically arranged receiving opening (40),
• an intermediate portion (30) arranged between the external toothing (10) and the receiving opening (40),
• a reinforcing structure arranged in the intermediate portion (30) having a plurality of openings (32, 33), and reinforcing ribs (34, 35) disposed between the openings, characterized by the following additional features:
• the external toothing (10) is designed as a helical toothing with a helix angle (W) to the axis of rotation (R),
• at least some of the openings (32, 33) follow at least approximately the helix angle (W) of the helical toothing with an opening angle (V),
• characterized in that the opening angle (V) is at least approximately formed according to the following formula:
• V=arctan(tan(W)×(R)/(d0/2)),
• where
• d0/2=half the pitch diameter of the external toothing (10),
• R=distance from the center of one of the openings (32;
• 33) to the axis of rotation (R).