1. Field of the Invention
The present invention relates to an inner rotor brushless motor that is used in a vehicle air conditioner, a battery cooling apparatus, or the like.
2. Related Art
As one example, an outer rotor DC brushless motor used as the driving apparatus for a fan used in a vehicle will now be described. A motor substrate on which a driving circuit is provided is split on two levels and enclosed inside an upper and lower housing that are made of resin. A concave is formed in the upper housing and a bearing sleeve is provided inside the concave so as to protrude vertically upward. A bearing shaft is rotatably supported in the bearing sleeve. The bearing shaft extends beyond the rotor and a fan is provided on the front end of the shaft. The stator core is assembled so as to be slidably fitted onto the bearing sleeve and contacts a stepped portion thereof.
When the rotor is rotated, air is sucked in from air inlets provided in a housing side surface and is expelled toward the fan from outlets provided in a rotor end surface so as to remove heat produced by the motor substrate and heat produced by the coils (see Patent Document 1). Also, although not limited to use in a vehicle, an inner rotor brushless motor that is equipped with means for detecting the rotational position and rotational velocity of the motor (and therefore has improved motor detection precision), and has been miniaturized by reducing the thickness in the radial direction has also been proposed (see Patent Document 2).
Patent Document 1
Japanese Laid-Open Patent Publication No. 2002-262517
Patent Document 2
Japanese Laid-Open Patent Publication No. 2005-229698