초록 ▼

An impeller and at least a portion of a cooperating peripheral volute may be integrated into, and preferably are integrally injection molded with, concentric outer rotor and inner stator assemblies, respectively, to achieve a low profile precision impeller mechanism based on an improved brushless d.

An impeller and at least a portion of a cooperating peripheral volute may be integrated into, and preferably are integrally injection molded with, concentric outer rotor and inner stator assemblies, respectively, to achieve a low profile precision impeller mechanism based on an improved brushless d.c. motor with low length (L) to diameter (D) ratio and suitable for use in a variety of other applications. In one practical embodiment of such a motor, a rotating cap has an inner circumference which is molded about an outer ferromagnetic back ring that in turn supports a permanently magnetized ring shaped rotor magnet having a number of poles of alternating polarity defined about its inner circumference and separated by a relatively small cylindrical air gap from the outwardly projecting radially oriented selectively magnetized poles of a fixed stator assembly. In one exemplary embodiment, the rotor may have 8 poles and the stator may have 9 poles. The fixed stator assembly is preferably integrally molded into a base housing that also includes a precision fixed bearing support that extends upwardly through the center of the stator assembly and that is rotatably coupled to a rotating shaft that extends downwardly from (and preferably is integral with) the center of the rotating cap. A coaxial pair of preloaded ball bearings is preferably supported between an inner cylindrical surface of the fixed bearing support and an outer cylindrical surface of the rotating shaft, to thereby permit the rotor to rotate precisely about the stator with minimal variation in the cylindrical air gap therebetween.

대표청구항 ▼

The invention claimed is: 1. An impeller mechanism incorporating a brushless dc motor, said mechanism comprising: a fixed portion further comprising a molded housing defining an internal axis of rotation and a lower portion of a peripheral volute, a separately fabricated stator assembly integrally

The invention claimed is: 1. An impeller mechanism incorporating a brushless dc motor, said mechanism comprising: a fixed portion further comprising a molded housing defining an internal axis of rotation and a lower portion of a peripheral volute, a separately fabricated stator assembly integrally molded within a base portion of the housing in an annular region between the axis and the volute, the stator assembly including a plurality of radially extending magnetizable teeth collectively defining a circumference of the stator assembly, and a respective electrical winding about each of the teeth for selectively magnetizing the individual teeth of the stator assembly, and a hollow bearing support concentric with the axis and extending though the stator assembly into the housing; a rotating portion further comprising a ring shaped brushless rotor assembly including a plurality of radially oriented permanently magnetized poles arranged about a circle, the rotor assembly encircling, in close proximity and concentric to the selectably magnetizable teeth of the stator assembly and separated therefrom by a cylindrical air gap concentric with a central axis and said air gap extending radially between the rotor assembly and the stator assembly, a ferromagnetic back-iron ring encircling the rotor assembly for providing a flux return path between two adjacent poles of the rotor assembly, a hat-shaped rotor support disposed about the axis and over the stator assembly, the rotor support including a downwardly extending outer lip on which is mounted the back-iron ring and a hollow crown extending upward of the outer lip, wherein the bearing support extends into the crown and the crown is above the stator assembly, an impeller assembly disposed on an upper side of the rotor support and over the air gap, a rotating shaft concentric with said axis and extending from an interior portion of the hollow bearing support into the crown of the rotating support; and a precision bearing assembly coupled between an interior surface of the hollow bearing support and an outer surface of the rotating shaft. 2. The impeller mechanism of claim 1, wherein the overall length of the mechanism along the axis from the bottom of the housing to the top of the crown portion of the rotating support is substantially less than the diameter of the peripheral volute. 3. The impeller mechanism of claim 2, wherein the hat shaped support is integrally molded about the back ring and the rotating shaft. 4. The impeller mechanism of claim 3, wherein the ring shaped rotor assembly is secured to an inner circumference of the back-iron ring after the downwardly extending lip portion of the hat shaped support has been molded about an outer circumference of the back-iron ring. 5. The impeller mechanism of claim 3, wherein the ring shaped rotor assembly is secured to the back-iron ring after the back-iron ring has been secured to the downwardly extending lip portion of the hat shaped support. 6. The impeller mechanism of claim 3, wherein at least a portion of the volute is integrally molded with the base portion of the housing, and at least a portion of the impeller is integrally molded with hat shaped rotor support. 7. A brushless motor mechanism comprising a stator portion further comprising a housing including a base portion defining an internal axis of rotation and at least a lower portion of a peripheral volute, a stator assembly secured within the housing about the axis, the stator assembly including a plurality of radially extending magnetizable teeth collectively defining an outer circumference of the stator assembly concentric with the axis, the stator assembly also including a respective electrical winding about each of the teeth for selectively magnetizing the individual teeth of the stator assembly, and a fixed bearing support concentric with the axis and extending through the stator assembly into the housing; a rotor portion further comprising a ring shaped brushless rotor assembly including a plurality of radially oriented permanently magnetized poles arranged about a circle, an inner surface of the rotor assembly in close proximity and concentric to the selectably magnetizable poles of the stator assembly and separated radially therefrom by a cylindrical air gap concentric with the axis, a ferromagnetic back-iron ring encircling an outer surface of the rotor assembly for providing a flux return path between two adjacent poles of the rotor assembly, a rotating support disposed about the axis above the stator assembly, the rotating support including a raised hollow crown portion above the stator assembly, the rotating support also including an annular base rim at the periphery of the crown and said base rim having a downwardly extending outer lip secured to the back-iron ring, wherein the base rim overhangs the stator assembly, a rotating bearing support concentric with the fixed bearing support and extending along the axis into the hollow crown portion of the rotating support; and a bearing assembly coupled between the fixed bearing support and the rotating bearing support, the bearing assembly being oriented along the axis, wherein the housing is molded about the fixed bearing support and the stator assembly, the rotating support is molded about the rotating bearing support and the back-iron ring, at least a lower portion of a peripheral volute is integrally molded with at least the base portion of the housing, an annular impeller is integrally molded with the rotating support, the impeller assembly is disposed on an upper side of the annular base rim of the rotating support, the base rim portion is disposed between the crown portion and the volute, an upper portion of the housing and crown portion of the rotating support cooperate to define an annular inlet to the impeller assembly, and an outer circumference of the impeller assembly is in direct communication with the peripheral volute. 8. The brushless motor mechanism of claim 7 wherein the bearing is a precision bearing assembly comprising a pair of spaced apart preloaded ball bearing races. 9. A method of constructing a brushless motor mechanism, comprising the steps: forming a stator assembly including a plurality of radially extending magnetizable teeth collectively defining an outer circumference of the stator assembly, the stator assembly also including a respective electrical winding about each of the teeth for selectively magnetizing the stator assembly and a plurality of electrical terminals for selectively activating said windings; forming a hollow bearing support defining a first axis; supporting the stator assembly concentric about the first axis in a predetermined angular orientation; molding a housing base portion and at least a portion of an integral volute about the hollow bearing support and the thus-supported stator assembly to thereby form a first molded portion of the rotating mechanism with the hollow bearing support extending through the stator assembly into the base portion; forming a ferromagnetic back-iron ring; forming a shaft defining a second axis; supporting the ferromagnetic back-iron ring concentric about a second axis; molding a generally cup-shaped rotating support and at least a portion of an integral impeller about the shaft and the thus-supported back-iron ring to thereby form a second molded portion of the rotating mechanism with the shaft and hollow bearing support extending into the interior of a hollow cup portion of cup-shaped rotating support, and with the back-iron ring disposed within an outer lip of a base rim of the cup-shaped rotating support; forming a ring shaped brushless rotor assembly including a plurality of radially oriented permanently magnetized poles arranged about a circle; securing the rotor assembly to an inner circumference of the back-iron ring within the second molded portion to thereby form a rotating assembly with a flux return path between two adjacent poles of the rotor assembly; and disposing a low friction bearing between the shaft and the hollow bearing support to thereby couple the first molded portion to the rotating assembly such that the first axis is coaxially aligned with the second axis with the rotor assembly surrounding the magnetizable poles of the stator assembly and separated therefrom by a cylindrical air gap concentric with the axis, wherein the air gap is below the impeller and extends radially between the stator assembly and rotor assembly. 10. A fluid pump assembly comprising: a molded housing defining an internal axis of rotation and a peripheral volute, wherein the housing has a fluid inlet disposed on one side of the housing and a base on the opposite side of the housing; a bearing support mounted to the base of the housing and which is concentric with the axis and extends axially from the base towards the fluid inlet; a rotating section having a center hollow crown, wherein the bearing support protrudes into the hollow crown and the rotating section is rotatably attached to the bearing support; a first side of the rotating section including an impeller and an inlet aligned with the inlet of the housing, said impeller includes a base rim extending radially outward from a periphery of the crown and an impeller exhaust aligned radially with the peripheral volute; a second side of the rotating section, opposite to the first side, includes a mounting for a rotor of a brushless D.C. motor; the rotor is concentric with the bearing support, and said rotor has a rotor surface defining an annular ring of the rotor; a stator of the brushless D.C. motor which is integrally molded with the base, said stator is concentric with the bearing support and axially aligned with the base rim of the impeller, wherein said stator has a stator surface defining an annular ring of the stator, and an air gap of the motor extending radially between the annular ring of the stator and the annular ring of the rotor, wherein the stator, radial air gap and rotor are in a common plane perpendicular to the internal axis of rotation. 11. The fluid pump assembly of claim 10 wherein the fluid pump is a fan and the fluid inlet is an air inlet. 12. The fluid pump assembly of claim 10 wherein the rotating section and impeller are integrally molded together. 13. The fluid pump assembly of claim 10 wherein the molded housing is a split housing having a first housing section including the fluid inlet, an inner annular surface facing the impeller and a first volute section extending radially from the inner annular surface, and a second housing section including the base and a second volute section extending radially from the base, wherein the first housing section and second housing section mate together to form the housing. 14. The fluid pump assembly of claim 10 wherein the stator includes a plurality of radially extending magnetizable teeth collectively defining the stator surface. 15. The fluid pump assembly of claim 10 wherein the rotor includes a magnetic ring and a concentric ferromagnetic back-iron ring, wherein the magnetic ring includes the rotor surface. 16. The fluid pump assembly of claim 10 further comprising a shaft concentric with the axis and rotatably mounted in the bearing support, wherein the shaft is the attachment between the rotating section and bearing support. 17. The fluid pump assembly of claim 10 wherein the stator extends radially from the crown to underneath the base rim and impeller. 18. The fluid pump assembly of claim 10 further comprising a shaft mounted in and coaxial to the bearing support, wherein the shaft provides the attachment between the bearing support and hat-shaped rotating section. 19. The fluid pump assembly of claim 10 wherein the bearing support has an axial length, and a first portion of the axial length is within the hollow crown and a second portion of the axial length is attached to and radially inward of the stator. 20. The fluid pump assembly of claim 19 wherein the second portion of the axial length of the bearing support is in the common plane.