Patent ID: 7523917
Filing Date: 2009-04-28
Classification: F16K

Abstract:
1. A motor-operated valve provided with a reduction gear apparatus, comprising a valve body having a valve chamber and a valve seat; a valve element disposed so as to be capable of opening and closing an opening of the valve seat in the valve chamber; a valve rod for operating the valve element; a cylindrical can fixed to the valve body; a motor energizing device mounted in an outer peripheral portion of the can; a permanent magnet type rotor assembly which is supported rotatably on an inner peripheral portion of the can and is rotationally driven by the motor energizing device; a reduction gear apparatus for reducing the rotational speed. of the rotor assembly; and a screw mechanism for advancing and retreating the valve element with respect to the valve seat via the reduction gear apparatus by means of the rotational movement of the rotor assembly, the rotor assembly and the reduction gear apparatus being arranged in a space defined by the valve body and the can, wherein the reduction gear apparatus includes a sun gear integral with the rotor assembly; a fixed gear having a ring gear, which is fixed on the valve body side; a planetary gear which is supported on a carrier and meshes with the sun gear and the fixed gear at the same time; and an output gear having a ring gear meshing with the planetary gear, a cylindrical gear case which supports the fixed gear by an upper end portion is fixed to a holder fixedly arranged in a space in the can, and the output gear located in a space in the gear case below the fixed gear is directly or indirectly supported by the holder so as to be rotatable, wherein the fixed gear is fixed to the gear case in a state in which a plurality of extending elements extending from an upper end of the gear case intrude in concave portions provided concavely in an outer peripheral surface of the fixed gear, and an undercut portion is formed in both-side edges of the extending element, and a part of the fixed gear made of a synthetic resin is caused to intrude into the undercut portion by thermal fusion via an appropriate heating means, by which the fixed gear is fixed to the gear case so as to be unseparable.