Abstract: A method of designing a gear in which a tooth trace of the tooth flank, which is to be engaged with another mating tooth flank, is curved with respect to an axial direction of the body of the gear. The mating tooth flank of the mating gear is designed in such a manner that a desired tooth contact can be achieved. Accordingly, sufficient design precision can be attained. Furthermore, stress at the tooth flanks can be controlled when the gears are engaged with each other, thereby leading to high durability of the gears.

Abstract: The invention is a method of designing a gear, the method including: a first modeling step of modeling one tooth flank (4a) of one gear (W1a) in a CAD system, in such a manner that the one tooth flank (4a) is formed by continuously transitioning a tooth trace consisting of a circular arc (R1), from a tooth root of the gear to a tooth tip thereof; a first designing step of generating a tooth contact curve (R3) as a desired tooth contact position, on the one tooth flank (4a), in the CAD system; a second modeling step of modeling a hypothetical mating tooth flank (51) capable of coming in contact with the one tooth flank (4a) in the CAD system, in such a manner that the hypothetical mating tooth flank (51) is formed by continuously transitioning a hypothetical tooth trace consisting of a circular arc, from a tooth root of a gear to a tooth tip thereof; a second designing step of generating a mating tooth contact curve (R4) on the hypothetical mating tooth flank (51), so as to correspond to the tooth contact curv