GEAR MADE OF RESIN FOR ENGINE

摘要

PURPOSE:To prevent creation of gaps between a bush and a resin portion and occurrence of torsion by composing a resin gear of a resin portion constituting a core- forming rim portion and a resin portion constituting a tooth portion-forming rim portion and a tooth portion. CONSTITUTION:A resin gear is composed of a bush 1 and a resin portion 2 constituting a rim portion and a tooth portion. The resin portion 2 is composed of: a resin portion 20a which is formed by the first-time molding and constitutes a core- forming rim portion; and a resin portion 20b which is formed by the second-time molding and constitutes a tooth portion-forming rim portion and a tooth portion. The resin portion 20a is so formed that its thickness decreases in the direction toward the tooth portion, while the resin portion 20b is so formed that its cross- sectional area gradually increases in the direction away from a gate toward the tooth portion. In this case, at least the resin portions are formed of a thermoplastic resin.