Disk drive in-hub radial-gap spindle motor with coils generating axial fields

Claim 1

A brushless direct current motor comprising: a base; a shaft having a central axis extending from and fixedly attached to the base; a lower ring bearing having radially inner and outer races with its inner race fixedly attached to the shaft; an upper ring bearing having radially inner and outer races with its inner race fixedly attached to the shaft, the upper and lower bearings being spaced apart a fixed distance along said central axis; a hub mounted to the outer races of the lower and upper bearings and rotatable about a central rotational axis generally coincident with said central axis of the shaft, the hub having a radially outer hub rim, the outer hub rim, the shaft and the spaced-apart lower and upper bearings defining a generally annularly shaped cavity located between the shaft, the outer hub rim and the spaced-apart bearings; a magnetically segmented ring magnet attached to and located radially inwardly of the outer hub rim within said cavity for generating magnetic fields in a generally radial direction; a plurality of stator teeth circumferentially spaced around the rotational axis, each stator tooth having a radially outer face spaced from and located radially inwardly of the ring magnet so as to define a radial gap; a like plurality of magnetically permeable posts, each post extending in an axial direction generally parallel to the rotational axis and being connected to a corresponding stator tooth; a like plurality of conductive coils, each coil being wound around a corresponding post for generating a magnetic field in an axial direction through its corresponding post and its corresponding stator tooth when conducting electrical current; a ring flux guide of magnetically permeable material interconnecting adjacent posts in a generally circumferential direction; and a support disk attached to the shaft, the support disk being attached to and supporting said interconnected stator teeth, posts, coils and ring flux guide within said cavity; whereby magnetic flux from the ring magnet is directed radially inwardly across the radial gap to the face of a first stator tooth, axially through the post and coil on said first stator tooth, circumferentially by the ring flux guide to the post and coil on a second stator tooth adjacent said first stator tooth, axially through the post and coil on said second stator tooth, radially outwardly from the face of said second stator tooth across the radial gap to the ring magnet.