Patent Publication Number: US-11661945-B2

Title: Motor-fan assembly with improved airflow and noise reduction properties

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a continuation application of prior application Ser. No. 15/782,990 filed Oct. 13, 2017, which is incorporated by reference. 
    
    
     TECHNICAL FIELD 
     Generally, the present invention is directed to a motor-fan assembly. Specifically, the present invention is directed to a motor-fan assembly that utilizes a housing assembly with reverse motor cooling airflow and other associated structural features to improve motor cooling airflow properties that better cool the internal electronics, allows increased power and reduces fan noise. In particular, the present invention employs replaceable inserts to allow either ambient air or off-site filtered cooling air into and out of the housing assembly. 
     BACKGROUND ART 
     Motor-fan assemblies are well known for generation of a directed airflow. Applications using a directed airflow include, but are not limited to, material handling/drying, air sampling, cooling applications, ink drying, and cleaning systems. 
       FIG.  1    shows a Prior Art motor-fan assembly designated generally by the numeral  50 . The assembly  50  includes a motor enclosure  52  with a motor section  54  connected to a fan section  56 . A working air inlet  58  axially extends from the fan section  56  which carries a working fan assembly designated generally by the numeral  60 . Air is drawn in through the inlet  58  and expelled out a tangential working air outlet  62 . A motor blower bracket  64  connects the sections  54  and  56  to one another while keeping the working air isolated from the motor section. The motor section  54  includes a circuit board  66  which is supported by the motor blower bracket  64 . Coupled to the circuit board  66  is a brushless motor  68  which includes a stator  70  and a rotor  72  which carries magnets in a manner well known in the art and wherein the rotor has extending therefrom a shaft  74  which extends through the motor blower bracket  64  and rotates the rotatable fans included in the working fan assembly  60 . Also connected to the shaft  74  is a cooling fan  76  maintained in the motor section  54 . The motor section  54  provides an axial cooling fan inlet  80  and a cooling fan outlet  82  which is typically radially directed from the motor section  54 . Rotation of the cooling fan draws air into the motor section  54  through the inlet  80  for the purpose of cooling the stator  70 , its associated windings, and the circuit board  66 . The cooling airflow then exits through the outlet  82 . 
     Although the Prior Art motor-fan assembly  50  is effective, it experiences performance issues that are fairly well known. The first significant issue is that the power output, especially in brushless-type configurations, is constrained by the positioning of the motor assembly and driving electronics within the motor section  54 . The stator windings and certain circuit components, namely a power module and a diode bridge, generate significant amounts of heat. If not adequately cooled, the associated electronics stop performing, which results in a thermal shutdown of the motor  68 . Operation of the cooling fan minimizes this from occurring, but overheating reduces operational performance of the motor assembly. It will also be appreciated that the heat, over time, decreases motor life. 
     The second significant performance issue is related to the generation of noise. The cooling fan flows air over the electronics, but the fan and inlet vents provide sharp edges which generate noise and most vents are axially disposed in relation to the cooling fan so that the noise permeates outwardly with little to no impediment. Filters and mufflers may be provided, but at an added cost and overall motor size increase. Additionally, the vents do little to prevent contaminants from entering the cooling air intake, especially when the motor is in an off condition. 
     Other drawbacks of current motor configurations are that the inlet and outlet vents are not easily adapted to modification. For example, if the cooling air is maintained in a dirty environment then filters are required, but the filters reduce the cooling airflow, which may lead to overheating. Special fixtures may also need to be mounted to the airflow inlets and outlets for the cooling air, but these are cumbersome and require construction of unique motor sections. Another drawback is that there are typically issues with contaminants from the cooling airflow entering into the working airflow. Finally, current motor-fan assemblies are not well suited for preventing heat migration from the working fan assembly via the motor shaft to the motor section. 
     Accordingly, there is a need in the art for a motor-fan assembly with improved airflow properties and noise reduction properties. In particular, there is a need for a motor-fan assembly that provides interchangeable inlet and outlet inserts for use with the cooling airflow to enable use of either ambient air or off-site air away from polluted areas. 
     SUMMARY OF THE INVENTION 
     In light of the foregoing, it is a first aspect of the present invention to provide a motor-fan assembly with improved airflow and noise reduction properties. 
     It is another aspect of the present invention to provide a motor-fan assembly, comprising an assembly housing which supports a motor assembly, a working fan assembly having a working fan rotated by the motor assembly which draws in and exhausts working air, a cooling fan assembly having a cooling fan rotated by the motor assembly which draws in and exhausts cooling air, the assembly housing comprising a motor vent cover associated with the cooling fan assembly, the motor vent cover having a sidewall with at least one vent hole therethrough, the sidewall having at least one socket aligned with the at least one vent hole, and a body having a tube opening extending therethrough, the body having an inner facing surface with at least one tail receivable in the at least one socket so that the at least one vent hole is contiguous with the tube opening. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings wherein: 
         FIG.  1    is a cross-sectional view of a prior art motor-fan assembly; 
         FIG.  2    is an exploded perspective view of a motor-fan assembly made in accordance with the concepts of the present invention; 
         FIG.  3    is a cross-sectional view of the motor-fan assembly made according to the concepts of the present invention; 
         FIG.  4    is a perspective view (working fan side) of a blower housing used in the motor-fan assembly according to the concepts of the present invention; 
         FIG.  5    is a side perspective view of the blower housing showing an installed inlet vent insert in accordance with the concepts of the present invention; 
         FIG.  6    is a different side perspective view of the blower housing with the inlet vent insert shown exploded away from the blower housing according to the concepts of the present invention; 
         FIG.  7    is a perspective view of the blower housing with an inlet tube insert shown exploded away from the blower housing in accordance with the concepts of the present invention; 
         FIG.  8    is a cross-sectional view of the blower housing according to the concepts of the present invention; 
         FIG.  9    is a cross-sectional view of a motor assembly used in the motor-fan assembly made in accordance with the concepts of the present invention; 
         FIGS.  10 A and  10 B  are respective top and bottom perspective views of a motor mount bracket used in the motor-fan assembly in accordance with the concepts of the present invention; 
         FIGS.  11 A and  11 B  are respective top and bottom perspective views of a circuit board incorporated into the motor-fan assembly in accordance with the concepts of the present invention; 
         FIG.  12    is a top perspective view of the circuit board, a stator assembly, and a rotor assembly assembled to the motor mount bracket according to the concepts of the present invention; 
         FIG.  13    is a top perspective view of a motor cover utilized in the motor-fan assembly according to the concepts of the present invention; 
         FIG.  14    is a bottom perspective view of the motor cover according to the concepts of the present invention; 
         FIG.  15    is a top view of the motor cover according to the concepts of the present invention; 
         FIG.  16    is a partial exploded perspective view showing a motor vent cover, a cooling fan assembly, and the motor cover according to the concepts of the present invention; 
         FIG.  17    is a top perspective view of the motor vent cover utilized in the motor-fan assembly according to the concepts of the present invention; 
         FIG.  18    is a bottom perspective view of the motor vent cover according to the concepts of the present invention; 
         FIG.  19    is a perspective view of the motor-fan assembly according to the concepts of the present invention; 
         FIG.  20    is a bottom perspective view of the motor vent cover showing an outlet tube insert according to the concepts of the present invention; 
         FIG.  21    shows the motor vent cover with the outlet tube insert exploded away from the motor vent cover according to the concepts of the present invention; 
         FIG.  22 A  is a rear perspective view of an outlet vent insert according to the concepts of the present invention; 
         FIG.  22 B  is a front perspective view of the outlet tube insert according to the concepts of the present invention; 
         FIG.  23    is a top view of an alternative motor vent cover utilized in the motor-fan assembly according to the concepts of the present invention; 
         FIG.  23 A  is an enlarged view of one-half of a sliding dovetail joint provided in the alternative motor vent cover according to the concepts of the present invention; 
         FIG.  24    is a top view of a slide-on outlet tube insert according to the concepts of the present invention; 
         FIG.  24 A  is an enlarged view of a mating half of a sliding dovetail joint provided in the slide-on tube insert according to the concepts of the present invention; 
         FIG.  25    is a rear perspective view of the slide-on tube insert according to the concepts of the present invention; and 
         FIG.  26    is a top perspective view of the slide-on tube insert assembled to the alternative motor vent cover according to the concepts of the present invention; 
         FIG.  26 A  is an enlarged view of the sliding dovetail joint that connects the slide-on tube insert to the alternative motor vent cover according to the concepts of the present invention; and 
         FIG.  27    is an exploded perspective view of the slide-on tube insert and the alternative motor vent cover according to the concepts of the present invention. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Referring now to  FIGS.  2  and  3   , it can be seen that a motor-fan assembly according to the present invention is designated generally by the numeral  100 . As generally described in the Background Art, a motor-fan assembly generates a working airflow for a particular end use and also a cooling airflow to cool the internal components of the associated motor assembly. 
     The motor-fan assembly  100  includes an assembly housing  102  which is made up of a number of major component parts that will be generally discussed in an overview of the assembly&#39;s operation. Following this general discussion, each of the major components and their component parts will be discussed. 
     The assembly housing  102  includes a working fan assembly  104  which draws in ambient air, which may or may not be filtered, and exhausts the working air as appropriate. In some applications, the vacuum generated by the working fan assembly is the primary purpose of the motor-fan assembly. In other embodiments, generation of the working air is desirable for a particular end use. In the embodiment shown, the working air is drawn in axially to the working fan assembly and exhausted tangentially from the housing  102 . In particular, the working fan assembly  104  includes a blower housing  106 , which is also part of the assembly housing, and which may be positioned on one side of the working fan assembly to assist in drawing the working air in and then exhausting the working air out as described above. 
     A motor assembly  110  is maintained in the assembly housing  102  on the side of the blower housing opposite the working fan assembly and which functions to rotate the working fan assembly  104  for generating the working airflow. The motor assembly  110  includes a rotatable shaft  112  which operates the working fan assembly. 
     A motor cover  114 , which may also be a part of the assembly housing  102 , covers the motor assembly  110  on a side opposite the blower housing  106 . The motor cover  114  assists in routing the cooling airflow, minimizing motor noise, and assists in keeping contaminants from entering into the motor assembly. A cooling fan assembly  116 , which is maintained adjacent the motor cover on a side opposite the motor assembly, is rotated by the rotatable shaft  112  and draws cooling air in from the blower housing  106 , wherein the cooling airflow passes through and around the motor assembly  110 . A motor vent cover  118 , which may also be a part of the assembly housing  102 , covers the cooling fan assembly  116  and may be coupled to the motor cover  114  and/or the blower housing  106  so as to provide for an exhaust path for the cooling air generated by the cooling fan assembly  116 . 
     The working fan assembly  104  may be of a standard construction. The assembly  104  includes a fan shell  122  which may be mounted to the blower housing  106  by friction fit, fasteners, or other means. The fan shell may provide an axial opening  124  which may also be referred to as a working air inlet. Contained within the working fan assembly may be a multi-stage fan  126  that operates in a manner known in the art. In the present embodiment, the fan  126  may include a rotating fan  128  secured to an end of the rotatable shaft  112  wherein the fan  128  includes an axial opening aligned with the axial opening  124  which pulls air in and expels the air radially within the fan shell. Next, the expelled radial air is received into a stationary fan  130  which is positioned axially adjacent the rotating fan  128 . The stationary fan  130  provides radial vanes which reroute the working air exhausted by the fan  128  to an axial opening that is on a side of the fan  130  opposite the rotating fan  128 . Skilled artisans will appreciate that the stationary fan  130  is secured within the fan shell and does not rotate with the shaft  112 . Another rotating fan  132  is positioned axially adjacent the stationary fan  130  and axially receives air from the stationary fan through an axial opening. The rotating fan  130  then radially exhausts the working air which then passes out the fan shell  122  via a working air outlet provided by the blower housing  106  as will be discussed. A spool spacer  134  may be secured to the shaft  112  and is employed to position and hold the rotating fans  128  and  132  on the shaft  112  and to allow for positioning of the stationary fan  130  between the rotating fans  128  and  132 . 
     A top hat spacer  140  may be secured to the shaft  112  and provides a slip fit therebetween. In some embodiments, an adhesive may be employed to secure the spacer  140  to the shaft. The spacer  140  extends through and into the blower housing  106  in a manner which will be discussed. The top hat spacer  140  includes a base  142  which may be positioned adjacent a facing surface of the rotating fan  132 . A column  144  extends from the base  142  and the spacer  140  has a spacer opening  146  that extends through the column so as to receive the shaft  112 . 
     Referring now generally to  FIGS.  2  and  3   , and specifically to  FIGS.  4 - 8   , it can be seen that the blower housing is designated generally by the numeral  106 . The blower housing  106  includes an outer wall  150  which may be generally cylindrically shaped and wherein a plurality of external mounting lugs  152  may extend radially outward from the outer wall  150 . The outer wall  150  may be split transversely by a chamber wall  154 . In the present embodiment, the chamber wall  154  includes a working fan side  156  which faces the working fan assembly  104  and a motor side  158  which faces the motor assembly  110 . The chamber wall  154  includes a spacer/shaft opening  160  which extends from one side to the other and receives the top hat spacer  140  and, in particular, the column  144 , wherein the rotatable shaft  112  is received in the spacer opening  146 . The top hat spacer and the received motor shaft  112  rotate within the spacer/shaft opening  160  in a manner that will be discussed. 
     The working fan side  156  may provide a volute  164  which gradually expands from an outer radial periphery of the blower housing toward a port  166  which extends tangentially from an exterior of the outer wall  150 . Together, the fan shell  122 , the working fan side  156  of the chamber wall  154 , and the outer wall  150  form a working fan chamber  165  which receives the multi-stage fan  126 . Generally, the multi-stage fan  126  draws working air into the chamber  165 , pressurizes the working air and propels the airflow toward the port  166 . The port  166  provides for a port opening  168  from which the working air is exhausted. As the working fan assembly  104 , and in particular the rotating fans  128  and  132  are rotated by the shaft, an airflow is drawn in through the axial opening  124  and the airflow generated by the rotating fan  132  is expelled into the volute  164 . The volute generally expands which allows for a corresponding expansion of the airflow until exiting the port opening  168 . 
     The motor side  158 , which is formed by the outer wall  150  and the chamber wall  154 , provides a volute wall  172  which extends from the chamber wall and is the other side of the volute  164  provided on the working fan side  156 . Together the volute wall  172 , the chamber wall  154 , and the interior surface of the adjacent wall  150  form a blower housing chamber  174 . The outer wall  150  provides for internally extending mounting lugs  176  which may provide for connection points to other components within the motor-fan assembly such as the motor assembly  110  as will be described. The motor side  158  of the blower housing  106  and in particular the outer wall  150  may provide for a cooling air inlet  178  which allows for entry of cooling airflow into the assembly housing  102 . As will be discussed in more detail, the cooling fan assembly draws cooling air in through the inlet  178  which is then routed internally through the assembly housing and out the motor vent cover  118 . In some embodiments, a deflector wall  179  may extend substantially perpendicularly from the motor side  158  of the chamber wall  154  in a position radially offset from the inlet  178 . The deflector wall  179  may serve to re-direct the incoming airflow within the blower housing chamber  174  and/or to reduce or muffle the amount of sound emanating from the motor assembly. The wall may be substantially concentric with the inlet  178  and the outer wall  150  or the deflector may be skewed in relation to the outer wall  150  to obtain a desired noise reduction or airflow within the chamber  174 . 
     In the present embodiment, the chamber wall  154  functions to separate the working fan assembly  104  from the remainder of the motor-fan assembly  100 . Referring back to  FIG.  1   , it will be appreciated that the prior art fan section  56  was positioned immediately adjacent the motor section  54 . As a result, heat generated by the working fan assembly migrated along the rotatable shaft toward and into the motor assembly  110 . In the present embodiment, the chamber wall  154  isolates the working fan assembly from the remainder of the motor-fan assembly  110  including the bearings associated therewith. 
     In some embodiments, the inlet  178  may simply be appropriately sized openings in the outer wall  150 . However, in the present embodiment the inlet  178  may be formed with replaceable inserts that allow the end-user to modify the motor-fan assembly in such a way as dictated by a particular end-use of the assembly and concerns as to whether the cooling air can be drawn from the surrounding ambient air or from a source of air that does not contain contaminants that might otherwise be found in the ambient air. In one embodiment, the blower housing  106  and, in particular the outer wall  150  on the motor side  158 , provides for an insert frame  180  which extends almost 90° along the arcuate length of the wall  150 . The frame  180  includes a frame bottom edge  182  along the outer wall  150 . The edge  182  may provide for a step wall  183  that perpendicularly extends from the frame bottom edge  182  and from which perpendicularly extends an insert step  184  which is aligned along the frame bottom edge  182 . In some embodiments, an edge groove  185  may be formed between an exterior surface of the outer wall and the step wall  183 . Extending substantially perpendicularly from each end of the frame bottom edge  182  are a pair of opposed insert tracks  186 . Formed between each of the tracks  186  is a track groove  190 . Accordingly, the insert frame  180  and, in particular the edge  182  and the tracks  186 , form an insert opening designated generally by the numeral  192 . 
     The wall  150 , on the motor side  158 , provides an outer wall edge  194 . At selected locations along the outer wall edge are a number of connector notches  196 . When the motor assembly is assembled to the blower housing  106 , the notches  196  are enclosed to provide selective access to switches and connectors associated with the motor assembly. 
     The insert opening  192  may receive an inlet insert  200  that forms the cooling air inlet  178 . In one embodiment the inlet insert may be an inlet vent insert  200 A ( FIG.  6   ) and in another embodiment the inlet insert may be an inlet tube insert  200 B ( FIG.  7   ). A vent insert  200 A allows for the entry of cooling air into the assembly housing  102 , as does the inlet tube insert  200 B. The inserts  200  may be of a generally arc shaped construction so as to be aligned with the cylindrical shape of the outer wall of the blower housing  106 . When the inlet tube insert  200 B is employed, a connection port is provided so that a tube or other hose-like configuration may be secured to the tube insert, wherein the opposite end of the connected tube has an inlet that is positioned away from the motor-fan assembly  100 . This allows for air from a clean or non-dirty source or filter attachment to be directed through the motor-fan assembly if desired. 
     The inlet vent insert  200 A includes an arcuate body  202 A with an outer facing surface  203 A. Opposite the outer facing surface  203 A is an inner facing surface  204 A. The body provides for opposed side edges  206 A that are connected by a bottom edge  208 A. A top edge  210 A connects the side edges  206 A on the side opposite the bottom edge  208 A. An insert wall extension  212 A extends from the body  202 A and is of the same arc shape as the body  202 A. Extending from each side edge  206 A is an insert rail  214 A. The body  202 A also provides a number of openings  218  extending therethrough which may be slanted or otherwise configured. As best seen in  FIGS.  6  and  7   , the insert rails  214 A are receivable in the corresponding track grooves  190 . As a result, the inlet vent insert  200 A may be installed and removed as needed for a particular end use. 
     In place of the inlet vent insert  200 A, the inlet tube insert  200 B may be installed. The inlet tube insert  200 B is constructed in a manner similar to the insert  200 A, except that the vent openings  218  are replaced with a tube  224  extending from the outer facing surface  203 B. Otherwise, the components of the insert  200 B that are common with the insert  200 A are provided with the same identifying number, but a corresponding suffix. In any event, the tube  224  forms a tube opening  226  which serves as a connection point for a tube, hose, or filter media that provides clean cooling air to the motor-fan assembly as discussed above. 
     Both inserts may be held in place when the motor mount bracket  250  is secured to the blower housing  106 . The motor cover may also provide a bottom edge that further exerts a sealing force on the respective insert. 
     As best seen in  FIGS.  5 - 8   , the chamber wall  154  on the motor side  158  provides for a seal pocket designated generally by the numeral  230  which surrounds the shaft opening  160 . In the embodiment shown, the seal pocket  230  may be a non-circular shape although a circular shape may be employed if desired. Concentric around the shaft opening  160  and within the seal pocket is at least one concentric rib  232 . As best seen in  FIG.  8   , the top hat column  144  extends through the shaft opening  160  and a seal  240 , which may be made of an adhesive backed PTFE® (polytetrafluoroethylene), sold under the trademark GORE-TEX® manufactured by W.L. Gore &amp; Associates, is placed and adhesively or frictionally held in the seal pocket  230 . In another embodiment, the seal  240  may be provided with non-circular or straight sides that are shaped similar to the seal pocket  230 . Or, the seal may be provided with straight sides wherein the pocket is circular in shape. In any event, it is desired that the seal and the seal pocket be configured so as to prevent rotation of the seal as the shaft rotates. Preventing rotation is also assisted by the concentric rib  232  which also assists in compressing the seal to prevent moisture migration. The seal  240  includes a seal opening  241  which is aligned with the shaft opening  160 . The seal also provides for a chamber side  242  which faces the seal pocket  230  and a motor bracket side  244  which faces outwardly into the blower housing chamber  174 . Operation of the seal  240  will be provided after a discussion of the motor assembly. 
     Referring now to  FIGS.  2  and  3  and  9 - 12   , it can be seen that the motor assembly is designated generally by the numeral  110 . The motor assembly rotates the shaft  112  which rotates the fans in the working fan assembly  104  and the fan in the cooling fan assembly  116 . The motor assembly may include a motor mounting bracket  250 . The bracket  250  may include a mounting plate  252  which includes a circuit board side  254  which generally faces the motor cover  114  and the motor vent cover  118 , and a blower housing side  255  which generally faces the blower housing  106 . The plate  252  is generally disc-shaped and in some embodiments is made of aluminum, or other material which functions as a heat sink. Extending from both sides of the mounting plate  252  is a tubular core  256  wherein the entire length of the core rotatably receives the rotatable shaft  112 . The core  256  includes an inner core wall  258  which is generally concentric with the rotatable shaft. The tubular core provides a blower end  260  which is received in the blower housing chamber  174 . The tubular core also provides a motor end  262  opposite the blower end  260 . The blower end  260  is positioned and supported by the seal pocket  230  and, in particular the motor bracket side  244  of the seal  240 . The blower end  260  provides an inward extension  261  of the inner core wall  258 , which forms a blower end hole  266  that receives the top hat spacer column  144 . Indeed, the column  144  of the top hat spacer  140  extends into the blower end hole  266 . Moreover, the blower end  260  is positioned adjacent the seal  240  and, in particular, the chamber side  242  of the seal  240 . When the motor assembly  110  is assembled to the blower housing  106 , a compressive force is directed through the mounting plate  252  and the tubular core  256  so as to exert a compressive force on the seal  240  which may have a smaller diameter opening than the diameter of the column  144 . Accordingly, as the shaft  112  and the spacer  140  rotate, a seal is formed between the inner diameter of the seal  240  and the outer diameter of the column  144 . 
     A bearing  268  is received between the inner core wall  258  and the shaft  112  near the inward extension  261  that forms the blower end hole  266 . A bearing spacer  270  may be interposed between the bearing  268  and the inward extension  261  of the inner core wall  258  which forms the blower end hole  266 . In some embodiments, a top edge of the column  144  may support an inner race of the bearing  268 . At the opposite end of the blower end hole  266 , at the motor end  262 , is an inner core step  272  which extends inwardly from the inner core wall  258 . A bearing  274  has an inner race secured to the shaft and an outer race received on and supported by the inner core step  272  so as to provide rotatable support between the shaft  112  and the inner core wall  258 . As will be appreciated by skilled artisans, the spacer  270  may be a wave spacer which takes any end play out of the balls in the bearings when compressed. When the fan assemblies  104  and  116  are assembled to the shaft  112 , the top hat spacer  140  is captured between an inner race of the earing  268  and the spool spacer  134 . 
     The mounting plate  252  is connected to the tubular core  256  at about a midpoint thereof by a plurality of connecting ribs  276 . The connecting ribs form a plurality of mounting plate vents  278  between the plate  252  and the core  256  which are concentric around the tubular core  256 . The mounting plate  252  may also provide for mounting plate flanges  280  which extend from the blower housing side  255  and which matingly fit into the blower housing  106 . The mounting plate  252  may also provide fastener openings  282  which extend therethrough and which are aligned with the internal mounting lugs  176 . Fasteners are received through the fastener openings  282  so as to secure the motor mounting bracket  250  to the blower housing which, in turn, results in the blower end  260  exerting a compressive force on the seal  240 . 
     Extending from the mounting plate  252  and in particular the circuit board side  254 , are a plurality of circuit board stand offs  286 . Additionally, the mounting plate  252  provides for a plurality of plate vents  288  that extend therethrough and which may be strategically placed in relation to the other features of the motor assembly. Heatsinks  290  may extend from the circuit board side  254  and, in some embodiments, a selected number of the vents  288  may be positioned along one or more sides of the heatsink  290 . Extending axially from the tubular core  256  is a bearing holder  292  which receives the previously discussed bearing  274  which is supported by the inner core step  272 . In some embodiments, an outer facing surface of the tubular core  256  may have a scallop  294  which is an inwardly curved portion positioned between the bearing holder  292  and the connecting ribs  276 . The scallop  294  extends around the outer periphery of the tubular core and, as will be discussed in further detail below, assists in the cooling airflow passing through the motor-fan assembly  100  and, in particular, the motor assembly  110 . 
     A circuit board  300 , best seen in  FIGS.  11 A and  11 B , which is part of the motor assembly  110 , includes a mount plate side  302  and a cooling fan side  304 . The mount plate side  302  is placed on to the circuit board stand offs  286  and secured thereto by appropriate fasteners. The mount plate side  302  may include a diode bridge, which may be positioned in proximity to the heatsink  290 , and a power module which may be positioned near the plate vents  288 . Other significant heat sources may be placed on the mount plate side  302 . Extending from the cooling fan side  304  is a stator assembly  312  which has an opening therethrough that aligns with a board opening  316  that extends through the circuit board which also receives the bearing holder  292 . The circuit board  300  also provides for a number of connectors  320  so as to receive diagnostic information and/or power. The circuit board also provides a number of DIP switches  322  which allow for adjustments to the operation of the electronics on the circuit board and, as a result, the motor assembly. 
     Referring back to  FIG.  9   , positioning of the circuit board  300  on the mounting plate  252  provides for an airflow gap  326  therebetween. The scallop  294  may be aligned with the airflow gap  326  so that cooling airflow passing through the vents  278  and  288  may pass underneath the circuit board and under the stator assembly and other slight openings between the circuit board, the connectors, the mounting plate, and the blower housing. Indeed, the outer wall edge  194  and an outer edge of the circuit board  300  may form a peripheral gap  318  that allows cooling airflow therethrough. The inner edge of the circuit board which forms the board opening  316  may be positioned in a void formed by the scallop  294  so as to form a scallop-board gap  328  that is contiguous with the airflow gap  326  to also allow cooling airflow. 
     A rotor assembly  330  is secured to an end of the shaft  112  opposite the working fan assembly. The assembly  330  includes a retaining ring  332  which is secured to the shaft wherein one end of the retaining ring is adjacent an inner race of the bearing  274 . The rotor assembly  330  further includes a rotor cup  334  which is secured to the retaining ring  332 . In the present embodiment, the ring  332  is formed in an injection molding process that utilizes molten zinc material or a zinc-based alloy which secures the rotor cup  334  to the shaft  112 . In other embodiments, a spacer and fasteners may be employed to hold the cup adjacent the shaft. The rotor cup includes a cup wall  336  which perpendicularly extends from a cup face  338 . The cup face  338  includes a central hole  340  which receives the retaining ring  332  and received shaft  112  therethrough. The face  338  also provides for a plurality of face vents  342  which are openings that extend through the cup face and allow for airflow therethrough. As is commonly understood, a plurality of motor magnets  344  are secured inside the cup wall  336  and face the stator assembly  312 . The retaining ring  332  is adjacent the inner race of the bearing in the bearing holder  292 . In view of the molded connection provided by the rind  332 , the cup  334  rotates with the shaft  112 . 
     Referring now to  FIGS.  2 ,  3 , and  13 - 16   , it can be seen that the motor cover is designated generally by the numeral  114 . The cover  114  is secured to the blower housing  106  by fasteners or the like and generally covers the motor assembly  110  and its components. The motor cover provides for a motor assembly side  350  which faces the motor assembly opposite a cooling fan side  352 . The motor cover  114  includes a cover wall  354  which is generally cylindrically shaped. The cover wall  354  includes a blower edge  355  that is positioned adjacent the blower housing  106 . Opposite the blower edge  355  is a platform edge  356 . 
     The cover wall  354  provides a number of outwardly radial external lugs  358  which receive fasteners for attachment to the blower housing  106  and, in particular, the external mounting lugs  152 . When attached, connector openings  359  with the connector notches  196  may be formed to allow access to the connectors  320 . Extending from the motor assembly side  350  to the cooling fan side  352  is a cover opening  360  which is axially aligned with the tubular core  256  and, in particular, the bearing holder  292 . As best seen in  FIG.  16   , the shaft  112  extends through the cover opening  360 . A spacer  361  may be secured to the shaft and may be positioned adjacent the retaining ring  332  and also extends through the cover opening  360 . The cover wall provides for a partial inset wall  364  which is substantially aligned with the cover wall  354  and fits around an upper edge of the blower housing. An inset ledge  366  may be provided between the cover wall and the inset wall. Extending from the platform edge  356 , which is perpendicular to the inset wall  364 , is a platform surface  362  which substantially encloses the motor assembly  110 . A portion of the platform surface is defined by a platform ramp edge  368 , which is somewhat semi-circular. Extending from an outer edge of the platform surface  362  is a peripheral ramp surface  370 . The ramp surface  370  includes an inner ramp wall edge  372  that is connected to the platform ramp edge  368  by a peripheral ramp wall  376 . The ramp surface  370  also includes an outer ramp wall edge  373  that connects to at least the partial inset wall  364 . In any event, the ramp surface  370  extends peripherally downwardly to a landing  374 . The ramp surface  370  extends laterally between the peripheral ramp wall  376 , which starts at the platform surface  362 , and the partial inset wall  364 . The ramp wall  376  may provide an outward flare  378  which intersects the inset ledge  366 . Extending inwardly from the platform surface  362  at the opening  360  is a collar  379 , which is positioned in proximity to the cup face  338 , wherein the face vents  342  are aligned within a cylindrical extension of the collar  379 . However, there is enough of a clearance between the cup face  338  and the collar  379  to allow cooling airflow to also pass therebetween. An underside of the platform surface  362  and an interior surface of the cover wall  356  form a motor assembly chamber  380  on the side opposite the cooling fan side  352 , wherein the motor assembly chamber  380  substantially encloses the rotor assembly  330  and the circuit board  300  of the motor assembly. 
     As best seen in  FIG.  16   , the cooling fan assembly  116  extends away from the motor cover, and in particular the cooling fan side  352  of the cover  114 . The spacer  361 , as previously discussed, is secured to an end of the shaft  112  wherein a fastener secures a cooling fan  384  to the shaft by a nut or other mechanism. The cooling fan includes a fan plate  390  which is secured by the nut to the rotatable shaft. Extending from the fan plate  390  are a plurality of curvilinear vanes  392  which on their opposite edge are connected to an entry plate  394  which has an axial opening  396  that faces and is axially aligned with the cover opening  360 . 
     Referring now to  FIGS.  2 - 3  and  16 - 18   , it can be seen that the motor vent cover  118  is secured onto the fan-motor assembly and, in particular, over the motor cover  114  with the cooling fan assembly therebetween. The motor vent cover includes a top  400  from which extends a cylindrical side wall  402  that has a lower edge  404 . A plurality of external lugs  406  may extend from a top edge of the side wall  402  for attachment to the motor cover  114 . The side wall  402  also provides a cover ramp edge  412  which matches the inset ledge  366  when the motor vent cover and motor cover are assembled to one another. A plurality of vents  414  may be provided in the side wall  402  and are aligned with the ramp surface  370 . Together the motor cover and the motor vent cover form a cover chamber  420 . It will further be appreciated that when the motor vent cover is secured to the blower housing that connector ports  422  may be formed so as to allow connection to the circuit board connectors  320  to monitor performance thereof. It will also be appreciated that the DIP switches  322  will be enclosed so that the motor&#39;s performance is not inadvertently changed. 
     In some embodiments the motor vent cover  118  may provide for an insert frame  430 . As with the blower housing, the vents in the side wall of the motor vent cover  118  may be replaced with a vent insert or a tube insert so as to allow for connection of an insertable vent or insertable tube so that the cooling airflow may connect to a tube that delivers the cooling airflow away from a dirty environment to an environment positioned away from the motor-fan assembly. As best seen in  FIGS.  19 - 22   , an insert frame  430  may be provided by the motor vent cover which includes a frame bottom edge  432  which provides for an insert step. A pair of opposed insert tracks  436  extend from each end of the edge  432  wherein the tracks each provide a track groove  440  therebetween. Together the bottom edge  432  and the tracks  436  provide for an insert opening  442 . The insert frame  430  is then able to receive an outlet insert  450 . In one embodiment the outlet insert is an outlet vent insert  450 A and in another embodiment the outlet insert is an outlet tube insert  450 B. 
     As best seen in  FIG.  22 A  the outlet vent insert  450 A includes a body  452 A with a slight curvature to match the outer curvature of the motor vent cover. The insert  450 A includes an outer facing surface  454 A opposite an inner facing surface  456 A. Connecting the surfaces to one another are a pair of opposed side edges  458 A, a bottom edge  460 A, and a top edge  462 A which connect the surfaces to one another. An insert wall  464 A may extend from the bottom edge  460 A. Provided on the side edges are a pair of insert rails  468 A which are received into the corresponding track grooves  440  and wherein the body includes vent openings  470  that extend between the facing surfaces  454 A and  456 A. A lug  472  may extend from the outer facing surface  454 A. 
     In the alternative, the outlet tube insert  450 B has substantially the same structure as the insert  450 A except for the provision of a body  452 B which includes a tube  474  that extends from the outer facing surface  454 B that provides for a tube opening  478 . 
     Either insert  450 A or  450 B is secured in the insert frame  430  when the motor vent cover is secured to the motor cover and/or the blower housing. The motor cover provides an edge which aligns with the bottom edge  460  so as to exert a sealing force on the respective insert. A fastener is inserted through the lug  472  and received in a corresponding lug  358  provided by the motor cover  114 . 
     Referring now to  FIGS.  23 - 27   , it can be seen that an alternative construction for securing a slide-on outlet tube insert on to a motor vent cover is shown. In this embodiment a motor vent cover is designated generally by the numeral  118 ′ as best seen in  FIGS.  23 ,  23 A and  27   . Unless designated otherwise, the motor vent cover  118 ′ provides for substantially the same component pieces as the motor vent cover  118 . The cover  118 ′ is substantially the same as the vent cover  118 , but with a slightly different configuration of the vent openings. The cover  118 ′ includes a top  400  with a substantially cylindrical sidewall  402 . In the present embodiment, the vents  414  are formed by a plurality of posts designated generally by the numeral  500 , wherein the posts are spaced apart and extend between the lower edge  404  and the top  400 . Each post  500  provides for a face  502 , wherein each face has inwardly directed sidewalls  504  which extend from each edge of the face. A recess surface  506  forms a top edge of the vent  414  while a stop edge  508  is disposed opposite the top edge of the vent and connects the opposed sidewalls  504  to one another. Together, the adjacent recess surface  506 , the sidewalls  504 , and the stop edge  508  form a sliding dovetail socket  510 . Any number of sockets  510  may be provided. Moreover, each socket  510  is aligned with a corresponding vent  414 . 
     As best seen in  FIGS.  24 ,  24 A,  25 , and  27   , a slide-on outlet tube insert is designated generally by the numeral  550 . The insert  550  is similar in construction to the insert  450 B but is provided with structural features which are slidably received in the sockets  510  of the cover  118 ′. The outlet tube insert  550  includes a body  552  with structural features similar to the insert  450 B. The body  552  provides an outer facing surface  554  which is opposite an inner facing surface  556 . Connecting the surfaces  554  and  556  to one another are a pair of opposed side edges  558 , a bottom edge  560 , and a top edge  562 . The body  552  provides a plurality of notches  570  which are spaced apart along the inner facing surface  556  along the bottom edge  560  and the top edge  562 . Each notch provides for an inwardly extending sidewall  572  which is connected by an inward surface  574  that connects the sidewalls  572  to one another. On either or both sides of each notch  570  is a tail  580 . Each tail  580  has a face surface  582  that connects the sidewalls  572  of adjacent notches  570  to one another. The tube insert  550  provides for a tube  586  that extends from the outer facing surface and provides for a tube opening  590 . As best seen in  FIG.  25   , the tails  580  and the notches  570  extend along the inner facing surface  556  from the top edge  562  to the bottom edge  560 , wherein the tails  580  and the notches  570  are interrupted by the tube opening  590 . 
     As best seen in  FIGS.  26 ,  26 A and  27   , the slide-on outlet tube insert  550  may be positioned onto the motor vent cover  118 . In particular, the notches  570  are received on the posts  502 . In a corresponding manner, the tails  580  are received in the sockets  510 . This forms a sliding dovetail joint that secures the slide-on tube insert to the motor vent cover. Once installed, application of an outward radial force on the tube insert will not dislodge it from the motor vent cover. As a result, the vents  414  are aligned and contiguous with the tube opening  590  to allow the cooling airflow to be exhausted through the outlet insert. The inward side walls  504  and  572  may be sized to provide a robust frictional fit between the sockets  510  and the tails  580  to prevent inadvertent dis-assembly of the insert  550  from the motor vent cover  118 ′. This provides for an add-on embodiment that allows for the motor vent cover to be employed and without having to utilize separate inserts that require the disassembly of the motor vent cover from the rest of the motor-fan assembly. 
     Generally, in referring to  FIGS.  2  and  3   , the operation of the motor-fan assembly is as follows. With energization of the motor assembly, the shaft is rotated so as to rotate the fans in both the working fan assembly and the cooling air fan assembly. In regard to the working fan assembly, working air is drawn in axially through the axial opening  124  and air travels through the rotating fan  128 , the stationary fan  130 , and the rotating fan  132  and into the working fan side  156  of the blower housing  106 . The blower housing  106  provides for a volute  164  which captures the air exhausted by the rotating fan  132  and the working air travels through the volute and out the port opening  168 . 
     As the shaft rotates, the cooling air fan assembly is also operating. In the present embodiment, the cooling air fan  384  generates a reverse air flow and, as such, air is pulled through the motor-fan assembly as opposed to being drawn in axially from the motor vent cover. Specifically, cooling air enters through the blower housing  106  and, in particular, through the inlet vent insert  200 A or the inlet tube insert  200 B. The inserts are positioned on the outer wall  150  on the motor side  158  of the blower housing. Air travels into and through the blower housing chamber  174  along the volute wall  172 . If provided, the deflector wall  179  may partially re-direct the cooling airflow within the chamber  174 . Airflow migrates through the chamber and into the motor assembly  110  and, in particular, along the tubular core  256  and through the vents provided by the mounting plate  252 . For air that travels along the tubular core  256 , it exits through the mounting plate vents  278  disposed between the tubular core and the mounting plate  252 . The scallop  294  allows for the air that flows through these vents to be redirected over the components provided on an underside of the circuit board. The vents that extend through the mounting plate and adjacent the heatsink flow over the components of the circuit board which generate the most heat and then from there into the area surrounding the rotor cup and into the motor assembly chamber  380 . The airflow may also proceed through the scallop-board gap  328  to flow over the cooling fan side  304  of the circuit board  300 . The cooling air then is drawn through the motor cover by the cooling fan and, in particular, through the cover opening  360 . The cooling air then impacts the underside of the top vent of the motor vent cover and then is pushed out through the peripheral ramp surface  370  and peripheral ramp wall  376  toward the vents  414 . Alternatively, the exhausted air may be expelled through the outlet vent insert  450 A or, if provided, the outlet tube insert  450 B. 
     As can be seen from the above, the present invention is advantageous in that the inlet and outlet for the cooling airflow is adaptable to provide removable and replaceable inserts which either provide for vented openings which maintain the shape of the motor-fan assembly in a cylindrical configuration or utilize a port insert which allows for connection of a hose or other tubular configuration to the port insert for both the inlet and outlet of the cooling air. Skilled artisans will appreciate the combination of either the port or a standard vent may be used for the inlet or the outlet as is appropriate. Such configurations allow for an end user to modify motor-fan assemblies as seen fit and also allow for connection of various other ducts or tubes to the inlet or outlet for the cooling air, wherein the cooling air can be drawn from areas away from a dirty environment and/or the clean air can be exhausted to areas away from the working environment. 
     Thus, it can be seen that the objects of the invention have been satisfied by the structure and its method for use presented above. While in accordance with the Patent Statutes, only the best mode and preferred embodiment has been presented and described in detail, it is to be understood that the invention is not limited thereto or thereby. Accordingly, for an appreciation of the true scope and breadth of the invention, reference should be made to the following claims.