Resin double helical gear pair

A resin double helical gear pair comprising:

• a first resin double helical gear on a drive side;
• and
• a second resin double helical gear gearing into the first double helical gear on a driven side, wherein
• the first double helical gear and the second double helical gear have the same diameter,
• the first double helical gear is formed so that at least an addendum modification coefficient of a peak of a chevron tooth is larger than addendum modification coefficients of other sections of said chevron tooth, and
• the second double helical gear is formed so that a sum of the addendum modification coefficient of the first double helical gear and an addendum modification coefficient of the second double helical gear in a gearing position of the first double helical gear and the second double helical gear is a constant value along a tooth width direction.

A resin double helical gear pair comprising:

• a first resin double helical gear;
• and
• a second resin double helical gear gearing into the first double helical gear, wherein
• the first double helical gear has a diameter smaller than a diameter of the second double helical gear,
• the first double helical gear is formed so that an addendum modification coefficient of a vicinity of a peak of a chevron tooth is larger than addendum modification coefficients of other sections of said chevron tooth, and
• the second double helical gear is formed so that a sum of the addendum modification coefficient of the first double helical gear and an addendum modification coefficient of the second double helical gear in a gearing position of the first double helical gear and the second double helical gear is a constant value along a tooth width direction.

A resin double helical gear pair comprising:

• a first resin double helical gear on a drive side;
• and
• a second resin double helical gear gearing into the first double helical gear on a driven side, wherein
• the first double helical gear and the second double helical gear have the same diameter,
• the first double helical gear is formed so that at least an addendum modification coefficient of a vicinity of a peak of a chevron tooth is larger than addendum modification coefficients of other sections of said chevron tooth, and
• the second double helical gear is formed so that a sum of the addendum modification coefficient of the first double helical gear and an addendum modification coefficient of the second double helical gear in a gearing position of the first double helical gear and the second double helical gear is a constant value along a tooth width direction.

A resin double helical gear pair comprising:

• a first resin double helical gear;
• and
• a second resin double helical gear gearing into the first double helical gear, wherein
• the first double helical gear has a diameter smaller than a diameter of the second double helical gear,
• the first double helical gear is formed so that an addendum modification coefficient is gradually decreased as a position is changed from a peak of a chevron tooth toward both ends in a tooth width direction of said chevron tooth, and
• the second double helical gear is formed so that a sum of the addendum modification coefficient of the first double helical gear and an addendum modification coefficient of the second double helical gear in a gearing position of the first double helical gear and the second double helical gear is a constant value along the tooth width direction.

A resin double helical gear pair comprising:

• a first resin double helical gear on a drive side;
• and
• a second resin double helical gear gearing into the first double helical gear on a driven side, wherein
• the first double helical gear and the second double helical gear have the same diameter,
• the first double helical gear is formed so that an addendum modification coefficient is gradually decreased as a position is changed from a peak of a chevron tooth toward both ends in a tooth width direction of said chevron tooth, and
• the second double helical gear is formed so that a sum of the addendum modification coefficient of the first double helical gear and an addendum modification coefficient of the second double helical gear in a gearing position of the first double helical gear and the second double helical gear is a constant value along the tooth width direction.

A resin double helical gear pair comprising:

• one resin double helical gear having multiple chevron teeth in the shape as if one helical gear is joined to the other helical gear with the skew direction different from that of the one helical gear in a center in a width direction;
• and
• the other resin double helical gear having multiple teeth gearing into the teeth of the one resin double helical gear, wherein
• the teeth of the one resin double helical gear are formed so that at least a pressure angle of the vicinity of the center in the tooth width direction is larger than a pressure angle of sections other than the vicinity of the center in the tooth width direction, and
• the teeth of the other resin double helical gear are formed so that a pressure angle is changed in the same manner as the teeth of the one resin double helical gear.

A resin double helical gear pair comprising:

• one resin double helical gear having multiple chevron teeth in the shape as if one helical gear is joined to the other helical gear with the skew direction different from that of the one helical gear in a center in a width direction;
• and
• the other resin double helical gear having multiple chevron teeth gearing into the teeth of the one resin double helical gear, wherein
• in the one resin double helical gear and the other resin double helical gear, a peak on a dedendum side of a chevron tooth and a valley section on a dedendum side of an adjacent tooth are connected by a stiffening rib protruding from a bottom in the central section in a tooth width direction, and
• in the one resin double helical gear and the other resin double helical gear, a stiffening rib recess groove along a rotational direction is formed in the central section in the tooth width direction of the tooth and on a tooth tip side of the tooth, so that the stiffening rib of a gearing counterpart does not interfere with the tooth in power transmission.