Low part count blower-motor assembly in common housing

Abstract

A low part count blower-motor assembly in a two-part housing which defines fluid inlet and discharge openings for the blower but which is otherwise sealed when assembled. An integrated tubular stator subassembly is fixedly attached to one of the housing parts and projects axially toward the fluid inlet opening. An integrated motor rotor subassembly is also disposed within the housing for rotation about the stator subassembly in coaxial relationship therewith, a part of the rotor subassembly being disposed axially between the stator and the inlet opening in spaced relationship with the opening. A shaft is journaled in the central opening of the tubular stator subassembly and projects axially there from toward the inlet opening and a fluid impeller mounted on the projecting end portion of the shaft receives fluid from the inlet opening. The impeller is also fixedly attached to the part of the rotor which resides between the stator and inlet opening.

Description

RELATED APPLICATION

Provisional application No. 60/508,414, titled “Blower with motor sealed inside” filed Oct. 2, 2003, inventors Robert A. Hoyt, David A. Curtis and Russel H. Marvin, incorporated herein by reference.

BACKGROUNG OF THE INVENTION

Typical blower-motor assemblies include at least three major subassemblies, the blower or impeller, an electric motor driving the blower, and one or more housings.

Part counts in these assemblies is high due primarily to the complexity of the electric motors and this of course leads to relatively inefficient assembly and manufacturing procedures. Conventionally, the motor is an external component and is connected in driving relationship with the blower by a drive shaft which passes through a blower housing. This arrangement results in high noise generation, air leakage at the shaft opening in the blower housing, air leakage through the motor bearings, and motor cooling problems if the blower is contained within an enclosed space.

It is a general object of the present invention to provide a low part count blower-motor assembly in a common housing whereby to eliminate air leakage between the motor and blower wheel thus improving performance, reducing noise generation, enhancing motor cooling, and protecting the motor from harmful environmental conditions. A further object of the invention is to provide for improved cooling of the motor by diverting a portion of the main air stream passing through the blower and directing it through the motor stator.

Another object of the invention is to provide integrated unitary stator and rotor assemblies, and in some instances integrated unitary rotor and blower or impeller assemblies thus aiding in minimizing part counts.

Finally, an important object of the invention is to provide a blower-motor assembly wherein at least the shaft and motor bearings are arranged in a housing in such a manner that there is no significant pressure drop across the bearings.

SUMMARY OF THE INVENTION

In accordance with the present invention and in fulfillment of the foregoing objects a two-part housing is provided and defines fluid inlet and discharge openings for a blower. The housing is otherwise sealed when the parts are joined together in assembly. An integrated tubular stator subassembly is fixedly attached to one of the housing parts and projects toward the fluid inlet opening. A motor rotor assembly which is also integrated is disposed within the housing in coaxial relationship with the stator assembly for rotation thereabout part of the rotor assembly being located axially between the stator and the inlet opening in the housing. A shaft is journalled in the central opening in the tubular stator and projects axially toward the inlet opening in the housing. Mounted on the projecting end portion of the shaft is a fluid impeller adapted to receive fluid from the inlet opening, the shaft being attached to the part of the rotor residing between the stator and the inlet opening and driven thereby.

Motor cooling is provided by openings connecting the interior of the stator and the upstream and downstream sides of the impeller, at least one of said openings having a flow-regulating device.

Preferably the construction of the stator assembly is in accordance with the teaching of U.S. application Ser. No. 10/679,143, Improved Permanent Magnet Motor, filed Oct. 2, 2003, herein incorporated herein by reference, with the entire assembly overmolded in an injection molding process resulting in a unitary component. Similarly, the rotor assembly is preferably constructed in accordance with the teaching of U.S. Application 60/508,413, Method for Making Rotor for Permanent Magnet Electric Machine, filed Oct. 2, 2003, herein by reference, with the entire assembly overmolded in am injection molding process resulting in a unitary component. A bearing tower, to be described herein below, is also constructed in accordance with the teaching of U.S. Application 60/442,407, herein by reference, with the entire assembly overmolded in an injection molding process resulting in a unitary component. Additionally, it should be noted that the rotor may be molded integrally with the impeller, thus further reducing the number of parts.

Finally, and in accordance with another aspect of the invention, the aforesaid integral components and other features are not essential, and it is only necessary the assembly be designed in a general way to provide the absence of any significant pressure drop across the bearings and the diversion of a portion of the main fluid flow from the impeller for flow through the motor and cooling of the same.

DESCRIPTION OF THE DRAWINGS

FIG. 1 of the drawings is a sectional view through the blower-motor assembly of the invention,

FIG. 2 is a sectional view similar to FIG. 1 but taken one hundred twenty degrees removed from the FIG. 1 view,

FIG. 3 is a fragmentary section similar to FIG. 2 showing connecting screws between the rotor and stator,

FIG. 4 is a further fragmentary section similar to FIG. 3 but showing regulating plugs installed in air passageways connecting the interior of the stator with a low pressure area near the impeller inlet,

FIG. 5 is a sectional view similar to FIG. 2 but emphasizing the unitary result and overmolding construction of the stator and rotor assemblies.

DESCRIPTION OF PREFERRED EMBODIMENT

Referring to FIG. 1, a low part count blower-motor assembly is indicated generally at 10 and includes upper and lower parts 12 and 14. The parts are adapted for snap-fit engagement at a tongue and groove joint 16. The upper part 12 carries a stator assembly 18 attached to the housing by screws 20, 20 (one shown) and which may be conventional or which may follow the teaching of the above mentioned U.S. application Ser. No. 10/679,143. The stator is tubular with annular windings at 19 and a bearing tower 22, which may be constructed in accordance with the aforementioned U.S. Application 60/442,407, supported in its central opening 24 in turn carries front and rear bearing units 26 and 28. The bearing units 26, 28 journal a shaft 30 which projects downwardly from the central opening of the stator toward a fluid inlet opening 32 on the lower or second housing part 14. A discharge opening is formed cooperatively by the two housings parts 12 and 14 at 33.

Supported by the stator assembly 18 for rotation thereabout is a rotor assembly 34 which may be conventional or which may follow the teaching of the aforementioned U.S. Application 60/508,413. The rotor assembly 34 carries one or more permanent magnet 36, 36 and has a radially extending part 38 which resides between the stator and the inlet opening 32.

A blower or impeller, shown as an air impeller 40, is mounted on the projecting end portion of the shaft 30 and rotor 38, which is then held in its axial proximity relative to the stator by screws 42, 42 which attach the stationary spring 54, 54 of the rotor to the stator assembly and is shown attached to the rotor part 38 by screws 42, 42, FIGS. 3, 4, and 5.

As will be apparent, the impeller 40 will draw air in through the inlet 32 and discharge the same radially outwardly under pressure as indicated by the arrows 44, 44 in FIG. 2. As is also indicated by the arrows 44, 44 the main air stream air makes a right angle turn upwardly along the wall of the lower housing part 14 and then leaves the housing through the discharge opening 33 after a second right angle turn. As indicated by the arrows 46, 46, a portion of the main air stream is diverted upwardly and radially inwardly at the top of the housing and enters the stator interior through openings 48, 48, one shown. The diverted or cooling air stream represented by the arrows 46, 46 continues downwardly through the central opening of the stator about the bearing tower 22 and exits through openings 50, 50 to the relatively low pressure area adjacent the inlet of the impeller, FIG. 3. The bearings and windings, critical components, are thus cooled in a highly efficient manner.

Referring to FIG. 4, plugs 52, 52 are provided for the openings 50, 50 and may serve as air flow regulating devices. That is, by properly dimensioning the plugs relative to their respective openings to regulate leakage or, for example, by providing vent openings of selected size, the air discharge area can be altered and the cooling effect regulated. From the foregoing, it will be apparent that an extremely low count blower assembly has been provided with the motor and blower in a compact arrangement in a common housing and with novel and highly effective cooling provisions for the motor.

Claims

1. A low part count blower-motor assembly in a common housing comprising a two-part housing which defines fluid inlet and discharge openings for the blower but which is otherwise sealed when assembled, an integrated tubular stator subassembly fixedly attached to one of the housing parts and projecting axially toward the fluid inlet opening, an integrated motor rotor subassembly disposed within the housing for rotation about the stator subassembly in coaxial relationship therewith, a part of the rotor subassembly being disposed axially between the stator and the inlet opening in spaced relationship with the opening, a shaft journaled in the central opening of the tubular stator subassembly and projecting axially from the opening toward the inlet opening, and a fluid impeller mounted on the projecting end portion of the shat to receive fluid from the inlet opening, said impeller also being fixedly attached to said part of the rotor residing between the stator and the inlet opening.

2. A low part count blower-motor assembly in a common housing as set forth in claim 1 wherein openings are provided respectively for communication between the interior of the stator subassembly and the upstream and downstream sides of the impeller, a flow of cooling fluid through the stator subassembly thus being provided.

3. A low part count blower-motor assembly in a common housing as set forth in claim 2 wherein a flow regulating device is provided for at least one of said stator openings whereby to control cooling of the motor.

4. A low part count blower-motor assembly in a common housing as set forth in claim 3 wherein the fluid is air, and wherein the flow regulating device is a plug in the associated opening and having an air flow passageway of predetermined area for controlling air flow through the stator.

5. A low part count blower-motor assembly in a common housing as set forth in claim 1 wherein the stator subassembly is overmolded in a plastic injection molding process to provide a unitary subassembly.

6. A low part count blower-motor assembly in a common housing as set forth in claim 1 wherein the rotor subassembly is overmolded in a plastic injection molding process to provide a unitary subassembly.

7. A low part count blower-motor assembly in a common housing as set forth in claim 1 wherein both the stator and rotor subassemblies are overmolded in plastic injection molding operations to provide unitary subassemblies.

8. A low part count blower-motor assembly in a common housing as set forth in claim 1 wherein the impeller is ultrasonically welded to the rotor part residing between the stator and the inlet opening.

9. A low part count blower-motor assembly in a common housing as set forth in claim 1 wherein the rotor and impeller are integrally molded simultaneously.

10. A low part count blower-motor assembly in a common housing as set forth in claim 1 wherein the housing parts are adapted for snap-fit interengagement.

11. A blower-motor assembly wherein at least the motor bearings and shaft are located in the blower housing in such a manner that no significant pressure drop occurs across the bearings, the motor including fluid flow passageways which divert a portion of the main fluid flow stream generated by the blower into one of said passageways through the motor and then out another of said passageways to rejoin the main fluid flow stream whereby to cool the motor.

12. A blower-motor assembly in a common housing which defines inlet and discharge openings for the blower but which is otherwise sealed, an annular stator fixedly attached to the housing and a rotor carried by the stator for rotation thereabout and in turn driving a fluid impeller, a shaft mounted within axially spaced bearings in the central opening of the tubular stator, inlet and discharge openings in the stator arranged to divert a portion of the main fluid stream generated by the impeller through the stator and thereby cooling the motor.

13. A blower-motor assembly as set forth in claim 12 wherein the fluid flow passageways are arranged to draw fluid from the downstream side of the blower and discharge the cooling air to the upstream side of the blower.

14. A blower motor assembly as set forth in claim 12 wherein the fluid flow passageways are arranged to draw fluid from the downstream side of the blower and discharge the cooling air to the upstream side of the blower but sub impeller for blower.

15. A blower-motor assembly as set forth in claim 14 wherein both the stator and rotor are of overmolded plastic construction.