Brushless D.C. motor assembly

Abstract

An improved motor assembly including a brushless D.C. motor and an annular member defining a platform for the drive electronics and speed control circuits of the motor. The member is carried on a fixed support within the outer envelope of the motor and includes a thin disk-like body providing a pair of opposed surfaces for mounting the components of the circuits. The fixed support of the motor has a flat annular face surrounding the drive shaft of the motor, and the annular member engages and is secured to the flat face of the support in surrounding relationship to the shaft. In a preferred embodiment, the housing of the motor defines part of the rotor of the motor and is for rotation with the shaft. A flange is secured to the support near the opposite end of the shaft for mounting the motor on a fixed support, such as on the base of a housing forming a part of a disk drive unit. Impeller blades can be secured to one end of the shaft or to the side of the housing to supply cooling air to a region adjacent to the motor.

We claim: 
     
       1. In a magnetic disk recording assembly of the type having a casing provided with a pair of adjacent air flow chambers separated by a wall with one of the chambers having a magnetic disk for rotation relative to a magnetic read-write head and the other chamber being isolated from the first chamber and containing first circuitry means for the head, the improvement comprising a brushless D.C. motor having an external housing; means coupled with the motor for mounting it on the casing externally of said one chamber, said motor having a fixed part and a shaft rotatable relative to the fixed part, the shaft adapted to extend through said wall of the casing and to be coupled at one end thereof to the magnetic disk for rotating the magnetic disk about its central axis, the motor having second circuitry means for controlling the excitation of the motor, and an annular support member carried by the fixed part in surrounding relationship to the shaft of the motor, said second circuitry means being mounted on the support member. 
     
     
       2. In a magnetic disk recording assembly as set forth in claim 1, wherein the external housing of the motor has means secured to the shaft for mounting the external housing on the shaft for rotation therewith, the housing having an open end, the fixed part being near the open end and the .[.circuitry mounting means.]. .Iadd.support member that mounts the second circuitry means .Iaddend.being exteriorly of the housing. 
     
     
       3. In a magnetic disk recording assembly as set forth in claim .Iadd.1 or .Iaddend.2, wherein the .[.mounting.]. means .Iadd.coupled with the motor for mounting it on the casing .Iaddend.includes a platform in a plane extending transversely to the shaft. 
     
     
       4. In a magnetic disk recording assembly as set forth in claim 3, wherein the annular member is secured to the fixed part and surrounds the shaft. 
     
     
       5. In a magnetic disk recording assembly as set forth in claim 1, wherein is included a fan mounted on the opposite end of the shaft for blowing air into the other chamber when the shaft rotates. 
     
     
       6. In a magnetic disk recording assembly as set forth in claim .[.1.]. .Iadd.3.Iaddend., wherein .[.the motor has an.]. .Iadd.said .Iaddend.external housing .Iadd.is .Iaddend.secured to the shaft for rotation therewith.[., and including a fan secured to the housing for blowing air into the other chamber when the shaft and housing rotate.].. 
     
     
       7. In a magnetic disk recording assembly as set forth in claim 6, .Iadd.and including a fan secured to the housing for blowing air into the other chamber when the shaft and housing rotate, .Iaddend.wherein said housing has an end face remote from the wall, the fan being on said end face. 
     
     
       8. An assembly as set forth in claim 6, .Iadd.and including a fan secured to the housing for blowing air into the other chamber when the shaft and housing rotate, .Iaddend.wherein said housing has a cylindrical outer surface, said fan including a number of spaced blades secured to said cylindrical outer surface. .Iadd. 
     
     
       9.  In a magnetic disk recording assembly as set forth in claim 1, wherein said second circuitry means comprises drive electronics means for motor commutation. .Iaddend. .Iadd.10. In a magnetic disk recording assembly as set forth in claim 1, wherein said second circuitry means comprises drive electronics means for motor commutation and speed control circuit means for controlling the speed of the motor. .Iaddend. .Iadd.11. In a magnetic disk recording assembly as set forth in claim 1, wherein said second circuitry means comprises means for sensing the position of the rotor of the motor. .Iaddend. .Iadd.12. In a magnetic disk transducer assembly of the type having a casing provided with a pair of adjacent air flow chambers separated by a wall with one of the chambers having a rotary disk-holding structure for a magnetic disk for rotation relative to a magnetic transducer head and the other chamber being isolated from the first chamber, the improvement comprising a brushless D.C. motor having an external housing; means coupled with the motor for mounting it on the casing externally of said one chamber, said motor having a fixed part and a shaft rotatable relative to the fixed part, the shaft adapted to extend through said wall of the casing and to be coupled at one end thereof to the magnetic disk for rotating a magnetic disk about its central axis, the motor having circuitry means for controlling the excitation of the motor, and an annular support member carried by the fixed part in surrounding relationship to the shaft of the motor, said circuitry means being mounted 
     
     
        on the support member. .Iaddend. .Iadd.13.  In a magnetic disk transducer assembly as set forth in claim 12, wherein the external housing of the motor has means secured to the shaft for mounting the external housing on the shaft for rotation therewith, the housing having an open end, the fixed part being near the open end and the support member that mounts the circuitry means being exteriorly of the housing. .Iaddend. .Iadd.14. In a magnetic disk transducer assembly as set forth in claim 12 or 13, wherein the means coupled with the motor for mounting it on the casing includes a platform in a plane extending transversely to the shaft. .Iaddend. .Iadd.15. In a magnetic disk transducer assembly as set forth in claim 14, wherein the annular member is secured to the fixed part and surrounds the shaft. .Iaddend. .Iadd.16. In a magnetic disk transducer assembly as set forth in claim 12, wherein is included a fan mounted on the opposite end of the shaft for blowing air into the other chamber when the shaft rotates. .Iaddend. .Iadd.17. In a magnetic disk transducer assembly as set forth in claim 12, wherein said external housing is secured to the shaft for rotation therewith. .Iaddend. .Iadd.18. In a magnetic disk transducer assembly as set forth in claim 17, and including a fan secured to the housing for blowing air into the other chamber when the shaft and housing rotate, wherein said housing has an end face remote from the wall, the fan being on said end face. .Iaddend. .Iadd.19. An assembly as set forth in claim 17, and including a fan secured to the housing for blowing air into the other chamber when the shaft and housing rotate, wherein said housing has a cylindrical outer surface, said fan including a number of spaced blades secured to said cylindrical outer surface. .Iaddend. .Iadd.20. In a magnetic disk recording assembly as set forth in claim 12, wherein said circuitry means comprises drive electronics means for motor commutation. 
     
     
        .Iaddend. .Iadd.21.  In a magnetic disk recording assembly as set forth in claim 12, wherein said circuitry means comprises drive electronics means for motor commutation and speed control circuit means for controlling the speed of the motor. .Iaddend. .Iadd.22. In a magnetic disk recording assembly as set forth in claim 12, wherein said circuitry means comprises means for sensing the position of the rotor of the motor. .Iaddend.