Patent Publication Number: US-11022131-B2

Title: Dual operation centrifugal fan apparatus and methods of using same

Description:
This application is a divisional of pending U.S. patent application Ser. No. 12/804,826, filed on Jul. 29, 2010 and entitled “Dual Operation Centrifugal Fan Apparatus And Methods Of Using Same,” the entire disclosure of which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates generally to centrifugal fan apparatus, and more particularly to dual operation centrifugal fan apparatus for information handling systems and other devices. 
     BACKGROUND OF THE INVENTION 
     As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems. 
     Information handling systems and other devices often utilize blower apparatus or cooling fans to regulate temperature generated within a chassis of the device. For example, notebook computers and similar devices often employ a blower to cool the system chipset together with other heat sources that may be present within the chassis. Due to notebook computer architecture and component placement, the blower inlet is typically defined in the bottom of the system where there is a greater probability that the blower fan will ingest dirt, lint and other impurities that over time tend to clog the thermal heat sink and/or other system components, leading to reduced thermal efficiency of the system. When this occurs, higher system temperatures result which leads to frequent activation of over temperature protection (OTP). 
       FIG. 1  illustrates a conventional axial fan assembly  100 , such as may be employed for cooling of a high voltage projector bulb  150  in a slide projector, or for cooling a server chassis. In such applications, sufficient room must be available within the chassis to accommodate the axial fan assembly  100 . As shown in  FIG. 1 , axial fan assembly includes a fan housing  102  that surrounds an axial fan and heat sink  104 . In  FIG. 1 , the axial fan is rotating in a first direction to draw in air though fan inlet  106  and expel the air from fan outlet  108 . As shown fan inlet  106  and fan outlet  108  are positioned in line with the rotational axis of the fan and the axial fan moves air through fan assembly  100  in an axial direction, i.e., in a direction parallel and in-line to with the rotational axis of the fan as illustrated by the arrows in  FIG. 1 . When so rotated, the axial fan draws air into the projector or server system chassis for purposes of dissipating heat from heat generating components therein. 
       FIG. 2  illustrates the conventional axial fan assembly  100  of  FIG. 1  when the axial fan is rotating in a second direction that is opposite to the first direction of  FIG. 1 . As shown in  FIG. 2 , air is moved in a direction opposite to that of  FIG. 1  when the rotation of the axial fan is reversed such that air is now drawn in though fan outlet  108  and expelled from fan inlet  106 , once again in a direction parallel and in-line to with the rotational axis of the fan as illustrated by the arrows in  FIG. 2 . By so reversing the axial fan direction, air may be expelled from a projector or server system chassis in a manner that removes accumulated dust from the chassis. 
     Centrifugal fan apparatus in the form of blowers are also employed to cool information handling systems such as notebook computers. Such blowers use a vaned rotor or bladed impeller that rotates within a blower stator housing. Unlike axial fan assemblies, such blowers draw in air at an axial opening near the shaft of the impeller and blow air out an opening that is located circumferentially to the impeller and in a direction that is oriented at a right angle to the direction of air intake. Further, such blowers always intake air from the axial air opening and exhaust the air from the circumferential opening, regardless of the direction of rotation of the impeller.  FIG. 3  illustrates an example of a conventional blower assembly  150  having a stator housing  156  with a vaned rotor  154  coupled thereto to rotate about its center axis relative to the stator housing  156 . A stator housing cover  160  is configured with an axial air opening  162  defined therein to overlie rotor component  154  when assembled thereto as shown by the dotted lines. An air exhaust opening  159  is shown present for exhausting air from blower  150 . Rotor  154  includes angled directional vanes and rotor component is rotatably received within a rotor cavity  158  defined in stator housing  156 . Directions of rotor rotation, air intake, and air exhaust for conventional blower  150  are indicated by the arrows in  FIG. 3 . Such a blower  150  may be installed within the chassis of an information handling system, such as notebook computer, in a manner such that axial air opening  162  extends through an outside wall of the chassis to draw in external cooling air, and such that air exhaust opening  159  exhausts cooing air into the interior of the chassis during blower operation. 
     SUMMARY OF THE INVENTION 
     Disclosed herein are dual operation centrifugal fan apparatus and methods of operating same that may be used, for example, to cool the internal heat-generating components of an information handling system or other device. The disclosed dual operation centrifugal fan apparatus may be implemented in one exemplary embodiment as a self-cleaning blower apparatus that is operated in a first normal cooling direction to dissipate heat from internal components of an information handling system, and operated in second cleaning direction to reverse airflow and expel accumulated debris (e.g., dust) from the interior of the information handling system. Advantageously the configuration of the disclosed dual operation centrifugal fan apparatus may be configured in such an embodiment to provide a relatively flat low profile for installation in small or thin form factor applications, e.g., such as inside a portable information handling system such as notebook computer. In another embodiment, a system design may be provided for operating the disclosed dual operation centrifugal fan apparatus that is substantially fault proof and flexible to better tolerate abuse from system users and/or environmental conditions by automatically implementing cleaning cycles, e.g., at regular intervals without need for user intervention. 
     The disclosed dual operation centrifugal fan apparatus may be provided with a stator housing component having an axial air opening adjacent the center axis of a vaned fan rotor component, and at least first and second circumferential air openings may be defined in the stator housing component beyond the periphery of the rotor component. The axial air opening may be inline with the axis of rotation of the rotor component and serve as an air inlet for the centrifugal apparatus when the rotor is rotating in a first (e.g., cooling) direction. Unlike a conventional axial fan, the circumferential placement of the first and second air openings in the stator peripheral to the rotor component may be implemented to advantageously provide a low blower fan profile to allow for placement in narrow or space-limited areas, such inside a notebook computer chassis. 
     In one exemplary embodiment, the first circumferential air opening may be configured and positioned to expel air that is drawn from the axial air opening when the rotor component is rotating in a first (e.g., cooling direction), and the second circumferential opening may be configured to expel air drawn from the first circumferential opening when the rotor component is rotating in a second (e.g., cleaning) direction that is opposite in direction from the first direction. In this way a dual operation centrifugal fan apparatus may be provided that reverses air flow direction when the rotation direction of the rotor component is reversed. This is unlike conventional blower apparatus which operate to expel air out of the same circumferential air opening regardless of the rotation direction of the blower rotor. 
     In one exemplary embodiment, a second circumferential opening of a dual operation centrifugal fan apparatus may be positioned in the stator housing (e.g., adjacent a relatively turbulent area of the stator housing interior) such that minimum or substantially no air leakage into the stator occurs through the second circumferential opening when the rotor component is rotating in the first (e.g., cooling) direction. In a further embodiment, a second circumferential opening may be provided with an optional sealing component (e.g., self-closing flapper door that closes due to inward air pressure differential) to substantially prevent air from being drawn in through the second circumferential opening when the rotor component is rotated in the first direction. 
     In another exemplary embodiment, a stator housing component may be configured with first and second circumferential air openings that each expel at least some air drawn in from the axial air opening when the rotor component is rotating in both first (e.g., cooling direction) and second (e.g., cleaning) directions. In this regard, the second circumferential opening may be configured and positioned to expel at least a portion of the air drawn from the axial air opening when the rotor component is rotating in the second (e.g., cleaning) direction, while the first circumferential air opening is configured and positioned to expel at least a portion of the air that is drawn from the axial air opening when the rotor component is rotating in a first (e.g., cooling direction), that is opposite in direction from the second direction, with the proviso that for any given blower assembly configuration a relatively greater amount of air is dispelled out the first circumferential opening during cooling rotation than is dispelled out the first circumferential opening during cleaning rotation, and a relatively greater amount of air is dispelled out the second circumferential opening during cleaning rotation than is dispelled out the second circumferential opening during cooling rotation. Thus, even though both first and second circumferential openings exhaust some air regardless of the direction of rotor component rotation in this embodiment, the relative amount of air exhausted by a given circumferential opening may be controlled by selecting direction of rotor component rotation. Due to this change in relative air flow relation between the first and second circumferential openings, at least a portion of accumulated dust (e.g., within the rotor cavity adjacent the first circumferential opening) may be exhausted from the second circumferential opening when the rotor component is reversed to rotate in the second (e.g., cleaning) direction. 
     In another exemplary embodiment, a system BIOS or other firmware executing on a processing device (e.g., such as an embedded controller) of an information handling system may be provided to automatically and/or selectably switch the rotation of the rotor of a dual operation centrifugal fan apparatus between a first (e.g., cooling) direction and a second cleaning direction to clean dust from the inside of the information handling system chassis and/or stator housing component on a regular or recurring basis. For example, the rotation of the rotor may be set by a processing device to the second (e.g., cleaning) direction for relatively short duration of time to periodically clean dust from the inside of the chassis and/or housing component, e.g., at occurrence of every power up of the information handling system and/or power down of the information handling system. In another example, a processing device may set the rotation of the rotor to the second cleaning direction after a given amount of elapsed operating time in the first (e.g., cooling) direction, i.e., to periodically clean dust from the inside of the information handling system chassis and/or stator housing component on a regular or otherwise timed interval. 
     In yet other possible examples, the rotation of the rotor may be set by a processing device to the second (e.g., cleaning) direction for relatively short duration of time based upon elevated sensed operating temperature inside the information handling system chassis and/or based upon input from a user of the information handling system, e.g., via graphical user interface and/or input/output device such as function key of the keyboard. Alternatively, the rotation of the rotor may be set by a processing device to the second (e.g., cleaning) direction for relatively short duration of time based upon detection of the accumulation of a predetermined amount of dust within the information handling system chassis using dust detection circuitry and/or methodology as described in U.S. Pat. No. 7,262,704, which is incorporated herein by reference in its entirety. Thereafter the rotation of the rotor may be returned to the first cooling direction. 
     In one respect, disclosed herein is an information handling system, including a chassis enclosing one or more information handling system components, the chassis having at least one gas intake opening defined in an outer surface of the chassis, and at least one cleaning gas exhaust opening defined in an outer surface of the chassis; and at least one centrifugal fan apparatus coupled to the chassis. The centrifugal fan apparatus may include: a stator housing component and a vaned rotor component rotatably received therein, a rotor driver mechanically coupled to drive the vaned rotor component in a first cooling direction and a second cleaning direction that is opposite in rotation from the first cooling direction, a first circumferential opening defined in the stator housing, the first circumferential opening configured to act as a gas outlet for expelling gas into an interior space of the chassis for cooling the information handling system components when the vaned rotor component rotates in a first cooling direction, a second circumferential opening defined in the stator housing, the second circumferential opening coupled to the at least one cleaning gas exhaust opening defined in the outer surface of the chassis and being configured to act as a gas outlet for expelling gas outside of the chassis when the vaned rotor component rotates in a second cleaning direction that is opposite in rotation from the first cooling direction, and an axial gas opening defined in the stator housing component over the vaned rotor component, the second circumferential opening coupled to the at least one gas intake opening defined in the outer surface of the chassis, and the axial gas opening configured to act as a gas inlet for drawing in gas from outside the chassis when the vaned rotor component rotates in the first cooling direction. 
     In another respect, disclosed herein is a centrifugal fan apparatus, including: a stator housing component and a vaned rotor component rotatably received therein; a first circumferential opening defined in the stator housing, the first circumferential opening configured to act as a gas outlet when the vaned rotor component rotates in a first direction; a second circumferential opening defined in the stator housing, the second circumferential opening configured to act as a gas outlet when the vaned rotor component rotates in a second direction that is opposite in rotation from the first direction; and an axial gas opening defined in the stator housing component over the vaned rotor component, the axial gas opening configured to act as a gas inlet when the vaned rotor component rotates in the first direction. 
     In yet another respect, disclosed herein is a method of operating an information handling system, including: providing a chassis enclosing one or more information handling system components, the chassis having at least one gas intake opening defined in an outer surface of the chassis, and at least one cleaning gas exhaust opening defined in an outer surface of the chassis; and providing at least one centrifugal fan apparatus coupled to the chassis. The centrifugal fan apparatus may include: a stator housing component and a vaned rotor component rotatably received therein, a first circumferential opening defined in the stator housing and configured to act as a gas outlet for expelling gas into an interior space of the chassis, a second circumferential opening defined in the stator housing, the second circumferential opening coupled to the at least one cleaning gas exhaust opening defined in the outer surface of the chassis, and an axial gas opening defined in the stator housing component over the vaned rotor component, the second circumferential opening coupled to the at least one gas intake opening defined in the outer surface of the chassis. The method may include rotating the vaned rotor component in a first cooling direction to draw in gas from the at least one gas intake opening defined in the outer surface of the chassis through the axial gas opening defined in the stator housing component, and to expel the drawn in gas into the interior space of the chassis through the first circumferential opening defined in the stator housing for cooling the information handling system components; and rotating the vaned rotor component in a second cleaning direction to expel drawn in gas from the second circumferential opening defined in the stator housing out through the cleaning gas exhaust opening to expel gas outside of the chassis. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a perspective view of a conventional axial fan assembly. 
         FIG. 2  illustrates perspective view of a conventional axial fan assembly. 
         FIG. 3  illustrates an exploded perspective view of a conventional blower assembly. 
         FIG. 4  is a block diagram of an information handling system according to one exemplary embodiment of the disclosed systems and methods. 
         FIG. 5  illustrates a perspective view of an information handling system according to one exemplary embodiment of the disclosed apparatus and methods. 
         FIG. 6  illustrates a dual operation centrifugal fan apparatus according to one exemplary embodiment of the disclosed apparatus and methods. 
         FIG. 7  illustrates a dual operation centrifugal fan apparatus according to one exemplary embodiment of the disclosed apparatus and methods. 
         FIG. 8  illustrates a dual operation centrifugal fan apparatus according to one exemplary embodiment of the disclosed apparatus and methods. 
         FIG. 9  illustrates a dual operation centrifugal fan apparatus according to one exemplary embodiment of the disclosed apparatus and methods. 
         FIG. 10  illustrates a dual operation centrifugal fan apparatus according to one exemplary embodiment of the disclosed apparatus and methods. 
         FIG. 11  illustrates a dual operation centrifugal fan apparatus according to one exemplary embodiment of the disclosed apparatus and methods. 
         FIG. 12  illustrates a dual operation centrifugal fan apparatus according to one exemplary embodiment of the disclosed apparatus and methods. 
         FIG. 13  illustrates a dual operation centrifugal fan apparatus according to one exemplary embodiment of the disclosed apparatus and methods. 
         FIG. 14  illustrates a dual operation centrifugal fan apparatus according to one exemplary embodiment of the disclosed apparatus and methods. 
         FIG. 15  illustrates a dual operation centrifugal fan apparatus according to one exemplary embodiment of the disclosed apparatus and methods. 
         FIG. 16  illustrates a dual operation centrifugal fan apparatus according to one exemplary embodiment of the disclosed apparatus and methods. 
         FIG. 17  illustrates a dual operation centrifugal fan apparatus according to one exemplary embodiment of the disclosed apparatus and methods. 
         FIG. 18  illustrates a dual operation centrifugal fan apparatus according to one exemplary embodiment of the disclosed apparatus and methods. 
     
    
    
     DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 
       FIG. 4  is a block diagram of an information handling system  200  (e.g., portable information handling system such as notebook computer, MP3 player, personal data assistant (PDA), cell phone, cordless phone, etc.) as it may be configured according to one exemplary embodiment of the disclosed systems and methods. As shown in  FIG. 4 , information handling system  200  of this exemplary embodiment includes a processor  205  such as an Intel Pentium series processor, an Advanced Micro Devices (AMD) processor or one of many other processors currently available. A graphics/memory controller hub (GMCH) chip  210  is coupled to processor  205  to facilitate memory and display functions. System memory  215  and a display controller  220  are coupled to GMCH  210 . A display device  225  (e.g., video monitor) may be coupled to display controller  220  to provide visual images (e.g., via graphical user interface) to the user. An I/O controller hub (ICH) chip  230  is coupled to GMCH chip  210  to facilitate input/output functions for the information handling system. Media drives  235  are coupled to ICH chip  230  to provide permanent storage to the information handling system. An expansion bus  240  is coupled to ICH chip  230  to provide the information handling system with additional plug-in functionality. Expansion bus  240  may be a PCI bus, PCI Express bus, SATA bus, USB or virtually any other expansion bus. Input devices  245  such as a keyboard and mouse are coupled to ICH chip  230  to enable the user to interact with the information handling system. An embedded controller (EC)  280  running system BIOS is also coupled to ICH chip  230 . 
     In this particular embodiment, information handling system  200  is coupled to an external source of power, namely AC mains  250  and AC adapter  255 . It will be understood that external power may alternatively provided from any other suitable external source (e.g., external DC power source) or that AC adapter  255  may alternatively be integrated within an information handling system  200  such that AC mains  250  supplies AC power directly to information handling system  200 . As shown AC adapter  255  is removably coupled to, and separable from, battery charger/power circuit  260  of information handling system  200  at mating interconnection terminals  290  and  292  in order to provide information handling system  200  with a source of DC power to supplement DC power provided by battery cells of a battery system in the form of smart battery pack  265 , e.g., lithium ion (“Li-ion”) or nickel metal hydride (“NiMH”) battery pack including one or more rechargeable batteries and a BMU that includes an analog front end (“AFE”) and microcontroller. Further, a battery system data bus (SMBus)  281  is coupled to smart battery pack  265  to provide battery state information, such as battery voltage and current information, from BMU  266  of smart battery pack  265  to EC  280 . Battery charger/power circuit  260  of information handling system  200  may also provide DC power for recharging battery cells of the battery system  265  during charging operations. 
       FIG. 4  further shows a centrifugal fan apparatus configured in the form of a self-cleaning blower apparatus  380  that is coupled to EC  280  by a control signal (e.g., communication bus)  381  to allow EC  280  and system BIOS executing thereon to selectably control rotation and direction of rotation of a vaned rotor or bladed impeller of blower apparatus  380  in a manner as will be described further herein. It will be understood that the embodiment of  FIG. 4  is exemplary only and that additional, fewer, and/or alternative components may be present in an information handling system of other embodiments. It will also be understood that any one or more other suitable other processing devices (e.g., controller, microcontroller, CPU, ASIC, FPGA, etc.) and software/firmware executing thereon may be alternatively employed to control operation of blower apparatus  380  in other embodiments. 
       FIG. 5  illustrates a perspective view of one exemplary embodiment of portable information handling system  200  as it may be configured as a notebook computer. As shown in  FIG. 5 , notebook computer  200  includes a lid chassis portion  308  with display (e.g. LCD or LED display) that is hingeably coupled to a base chassis portion  320  that in this embodiment includes input/output devices (e.g., such as a keyboard, touchpad, etc.) and that internally encloses or contains information handling system components (e.g., system processor  205 , main memory  215 , media drives  235 , battery charger and power circuit  260 , smart battery  265 , etc.) described in relation to  FIG. 4 . As further shown in  FIG. 5 , notebook computer  200  includes an air intake opening  350  defined in the underside surface  352  of base chassis portion  320  for a self-cleaning blower apparatus  380  (shown in dashed outline) that is provided inside notebook computer  200  for purposes of drawing in air to cool internal components of notebook computer  200 . Further shown in  FIG. 5  are cooling air exhaust openings  354  defined in the underside surface  352  of base portion  320  for allowing circulated cooling air provided by self-clean blower apparatus  380  to escape. Also present is cleaning air exhaust opening  356  defined on a backside surface  358  of base portion  320 . 
     As will be described further herein, self-cleaning blower apparatus  380  draws in air through cooling air intake opening  350  when its rotor is rotated in a first cooling direction and supplies this cooling air to the interior of information handling system base chassis portion  320  for cooling the components therein. The cooling air is then dispelled from base chassis portion  320  through cooling air exhaust openings  354 . When its rotor is rotated in second cleaning direction, self-cleaning blower apparatus  380  draws air from the interior of base chassis portion  320  and exhausts this cleaning air through cleaning air exhaust opening  356  in one embodiment, or draws in air through cooling air intake opening  350  and preferentially exhausts this cleaning air through cleaning air exhaust opening  356  in another embodiment. In the first aforementioned embodiment, the action of drawing air from the interior of base chassis portion  320  acts to dislodge and remove dust and other debris that may have been carried in by cooling air and accumulated inside base chassis portion  320  when the rotor of the self-cleaning blower apparatus  380  is operating in its normal first cooling direction. In the second aforementioned embodiment, the action of exhausting air preferentially through cleaning air exhaust opening  356  acts to dislodge and remove dust and other debris that may have been carried in by cooling air and accumulated inside the stator housing component of the blower apparatus  380  when the rotor of the self-cleaning blower apparatus  380  is operating in its normal first cooling direction. 
     It will be understood that the embodiment of  FIG. 5  is exemplary only, and that a self-cleaning blower apparatus  380  may implemented to cool other types of information handling system chassis (e.g., desktop computer chassis, server chassis, etc.) or other types of chassis (e.g., stereo chassis, refrigerator chassis, electric welder chassis, etc.). Further, the relative positioning and configuration of blower apparatus  380 , and openings  350 ,  354  and  356  are exemplary only and may varied in location and/or number, size, shape, etc. 
       FIGS. 6 and 7  illustrate a dual operation centrifugal fan apparatus  380  as it may be configured according to one exemplary embodiment of the disclosed apparatus and methods. It will be understood that although described in relation to an embodiment of a self-cleaning blower apparatus (e.g., for air cooling an information handling system chassis or other air cooling operation), the dual operation centrifugal fan apparatus described for the embodiments herein may be employed for any other gas-circulating purpose, and may be employed to circulate other types of gas besides air, e.g., oxygen, nitrogen, carbon dioxide, etc. 
     As shown in  FIGS. 6 and 7 , self-cleaning blower apparatus  380  includes a stator housing component  502  with a vaned rotor component  509  coupled thereto to rotate about its center axis  506  relative stator component  502 . The rotating center of rotor component  509  may be exposed or may be covered by a stationary plate. In  FIGS. 6 and 7 , one side (e.g., stator housing cover) of stator housing component  502  that overlies rotor component  509  is shown removed for illustration purposes. As shown, rotor component  509  includes angled directional vanes  504  that radiate from a central rotor member  507 , and rotor component is rotatably received within a rotor cavity  511  defined in stator housing component  502  that has a closed side that substantially conforms to the outer peripheral shape of vaned rotor component  509 . Rotor cavity  511  also includes an open side  523  that does not conform to the outer peripheral shape of vaned rotor  509  and that is open to and contiguous with a first circumferential opening  510  defined in the body of the stator housing component  502  that will be further discussed below. Rotor cavity  511  also includes a closed side  524  that is defined between the body of stator housing component  502  and rotor component  509 . Closed side  524  terminates as shown at a blocking surface  530  of the body of stator housing component  502  which is conformably located adjacent the outer periphery of rotation of vaned rotor component  509  to from a dynamic pneumatic seal that substantially blocks air flow (i.e., prevents bypass airflow) between the outer periphery of vaned rotor  509  and blocking surface  530 . 
     It will be understood that each of rotor component  509  and stator housing component  502  may be manufactured of metal, plastic, combinations thereof, etc. Not shown in  FIGS. 6 and 7  is a rotor driver (e.g., an electric fan motor) that is mechanically coupled to drive rotor component  509  in a first counterclockwise cooling direction as shown by the arrow in  FIG. 6 , and a second and opposite clockwise direction as shown by the arrow in  FIG. 7 . 
     As previously mentioned, a stator housing cover  802  of stator housing component  502  has been omitted from view in the previous figures. A stator housing component  502  may include a stator housing cover  802  that is formed as an integral feature with the remainder of stator housing component  502 , or may include a stator housing cover  802  that is formed as a separate piece from the remainder of stator housing component  502 . As shown in  FIG. 8 , stator housing cover  802  is configured to cover and at least partially enclose rotor cavity  511 , and includes an axial air opening  804  substantially centered over central rotor member  507  that functions as an air inlet for cooling air when rotor component rotates in its first counterclockwise cooling direction, it being understood that an axial air opening may be alternatively positioned in other way over central rotor member  507  suitable to allow air to be drawn in through the axial air opening by the rotating central rotor member  507 . As may be seen in the exemplary embodiment of  FIG. 8 , a portion of rotor vanes  504  are overlain and exposed by axial air opening  804  through which air is drawn in by self-cleaning blower apparatus  380  in a manner as will be described further herein. In the embodiment of  FIG. 5 , the stator housing cover may be formed by the underside surface  352  base chassis portion  320  of notebook computer  200  with air intake opening  350  being defined in the underside surface  352  of base chassis portion  320  and substantially centered around central rotor member  507  as shown to function as axial air opening  804  and as a cooling air inlet for blower apparatus  380 .  FIG. 8  also shows stator housing cover  802  in dashed-line exploded perspective view as it would appear if disassembled from stator housing component  502 . 
     As further shown in  FIGS. 6 and 7 , a first circumferential opening  510  is defined in the periphery of stator housing  502  adjacent and continuous with open side  523  of rotor cavity  511 . As shown, an optional grill or a heat exchanger fin assembly  595  may be optionally present across first circumferential opening  510 . First circumferential opening  510  functions as an air outlet when rotor component  509  rotates in its first counter clockwise cooling direction toward the direction of the angle orientation of vanes  504 . When rotated in this direction, the angle of directional vanes  504  acts to draw in air  655  through axial air opening  804  by virtue of an area of lower air pressure created in closed side  524  of rotor cavity  511  due to a pneumatic seal dynamically formed by blocking surface  530  with the distal ends  549  of vanes  504  during rotation. The rotating action of rotor  509  creates centrifugal force that dispels air  653  at first circumferential opening  510  in a direction that is oriented 90 degrees from the direction that the air  655  is taken in through axial air opening  804 . First circumferential opening  510  is faced by the oncoming angled front side face  551  of vanes  504  as they move toward open side  523  of rotor cavity  511  against blocking surface  530 , which acts to create an area of higher pressure that forces the air  653  out first circumferential opening  510 . When employed in the exemplary information handling system embodiment of  FIG. 5 , first circumferential opening  510  may communicate with the interior of base chassis portion  320  to allow blower apparatus  380  to supply cooling air drawn in through air intake opening  350  through first circumferential opening  510  to the interior components of base chassis portion  320  as shown in  FIG. 6 . 
     Also illustrated in  FIGS. 6 and 7  is a second circumferential opening  512  that is also defined in the periphery of stator housing  502  adjacent and that in this embodiment is open and contiguous with open side  523  of rotor cavity  511 . Second circumferential opening  512  functions as an air outlet for blower apparatus  380  when rotor component  509  rotates in its second clockwise cleaning direction as shown in  FIG. 7 . When so rotated, the angled face  552  of directional vanes  504  acts to draw in air  753  at first circumferential opening  510  as a result of an area of low pressure created in open side  523  of rotor cavity  511  between first circumferential opening  510  and rotor component  509  due to the dynamic pneumatic seal formed between the ends  509  of rotor vanes  504  and blocking area  530 . This air drawn in is forced out as air  755  through second circumferential opening  512  due to an area of high pressure created in closed side  524  of rotor cavity  511  as the oncoming angled back side face  552  of vanes  504  move through closed side  524  of rotor cavity  511  against blocking surface  530 . The size and shape of second circumferential opening  512  may be selected as needed to fit the air flow requirements of a particular application, e.g., to have sufficient cross-sectional area to exhaust maximum airflow provided by rotor component  509  when rotating in its second clockwise cleaning direction. It will be understood that the particular directional orientation of rotor vanes  504  is exemplary only, and that vanes  504  may be oriented to face the opposite direction to provide a clockwise cooling rotation (e.g., air intake through an axial inlet and air exhausted out a first circumferential opening) and a counter clockwise cleaning rotation (e.g., air intake through a first circumferential opening and air exhausted out a second circumferential opening). 
     In one exemplary embodiment, a user and/or system BIOS executing on embedded controller  280  of information handling system  200  may be provided to automatically and/or selectably control the direction of rotation of rotor component  509  of self-cleaning blower apparatus  380  to temporarily switch rotation of rotor component  509  from the normal first cooling direction to a second cleaning direction to clean dust from the inside of base chassis portion  320  of information handling system  200 , e.g., in response to manual user input, automatic algorithm steps, etc. For example a user may be allowed to initiate a temporary cleaning mode in which rotor component  509  temporarily switches from the normal first cooling direction rotation to the second cleaning direction, e.g., by input via function keystrokes input to keyboard  245  and/or by graphical user interface on display  225 . A utility may be optionally provided executing on processor  205  and/or embedded controller  280  that periodically reminds the user to implement the temporary cleaning mode. The duration of the second cleaning direction rotation of the temporary cleaning mode may be controlled by the user and/or automatically by timed algorithm (executing, for example, on embedded controller  280 ) prior to returning to the normal first cooing direction. Duration of second cleaning direction may be, for example, 5 to 10 seconds or any other suitable greater or lesser amount of time. An example automatic cleaning schedule would be two hours of first cooling direction rotation followed by 10 seconds of second cleaning direction rotation, before reversing rotation for two more hours of first cooling direction rotation. 
     Alternatively or additionally, system BIOS may initiate the second cleaning direction rotation of rotor component  509  on a regular or recurring basis, e.g., by implementation of an algorithm that temporarily switches the rotation of rotor component  509  from the normal first cooling direction to the second cleaning direction. For example, the rotation of the rotor component  509  may be temporarily set by BIOS executing on embedded controller  280  to the second cleaning direction for a relatively short duration of time (e.g., from about 30 seconds to about 1 minute or any other suitable time) to periodically clean dust from the inside of base chassis portion  320 , e.g., at occurrence of every boot up or power up of the information handling system  200  and/or power down of the information handling system  200 . For example, in one exemplary embodiment at every initial system boot the rotor component  509  may go idle (e.g., for about two seconds) after running in the first cooling direction at full speed (e.g., at about 4000 RPM) for a short period of time. It may then reverse to run in the second cleaning direction rotation (e.g., at about 2000 RPM) for about 15 seconds. It will be understood that these time and rotational speed parameters are exemplary and illustrative only. 
     In another example, BIOS executing on embedded controller  280  may temporarily set the rotation of rotor component  509  from the first cooling direction to the second cleaning direction to periodically clean dust from the inside of the information handling system base chassis portion  320  on an automatic timed interval. For example, BIOS executing on embedded controller  280  may temporarily set the rotation of rotor component  509  to the second cleaning direction after a given amount of cumulative elapsed operating time (e.g., from about 6 to about 12 hours or any other suitable time) in the first cooling direction, and then re-set the rotation of rotor component  509  back to the second cleaning direction after a short duration of cleaning time (e.g., from about 30 seconds to about 1 minute or any other suitable time). In yet other possible examples, the rotation of rotor component  509  may be temporarily set by system BIOS to the second cleaning direction for relatively short duration of time (e.g., from about 30 seconds to about 1 minute or any other suitable time) based upon sensed operating temperature exceeding a high temperature threshold inside the information handling system chassis (e.g., sensed by a temperature sensor coupled to a processing device and positioned within base chassis portion  320 ). Thereafter the rotation of rotor component  509  may be returned to the normal first cooling direction. 
     In one exemplary embodiment, a status indicator (e.g., dual color LED or other type of visual and/or audio indicator) may be provided to inform a user in real time of the information handling system of the current operational mode (e.g., cooling or cleaning fan rotation). For example a dual color LED indicator may be provided as one of the “dashboard” visual indicators of a notebook computer, or may be positioned adjacent cleaning and/or cooling exhaust openings of the information handling system. The status indicator may be lit with either a first or second color to indicate which corresponding respective fan rotation mode (cooling or cleaning) is currently in operation. 
     It will be understood that the preceding examples are exemplary only, and that any combination of user action, embedded controller  280 , processor  205  and/or other processing device may be employed to implement temporary cleaning cycles using any suitable methodology or algorithm. Further, it will be understood that where multiple fan speeds are employed for a self-cleaning blower apparatus  380 , the highest fan speed may be automatically selected in one embodiment for the second cleaning direction operation of rotor component  509 . 
     When employed in the exemplary information handling system embodiment of  FIG. 5 , second circumferential opening  512  may be coupled in communication with cleaning air exhaust opening  356  to allow cleaning air drawn in from the interior of base chassis portion  320  through first circumferential opening  510  to be expelled through air exhaust opening  356 . As previously mentioned, this action of drawing air from the interior of base chassis portion  320  acts to dislodge and remove dust and other debris that may have been carried in by cooling air and accumulated inside base chassis portion  320  when the rotor of self-cleaning blower apparatus is operating in its normal first cooling direction. It will be understood, however, that the disclosed self-cleaning blower apparatus may be employed for a variety of air moving purposes, including for applications not involving cooling and/or use in information handling systems. 
     It will be understood that the particular relative locations of first and second circumferential openings  510  and  512  relative to stator housing  502  in  FIGS. 6-8  are exemplary only, and that other locations and/or configurations are possible. For example,  FIG. 9  is a cut-away view of an alternative embodiment of self-cleaning blower apparatus  380  in which a second circumferential opening  512  may be defined in stator housing component  502  adjacent a relatively turbulent “blocking” region  902  of the stator housing interior such that minimum or substantially no air leakage occurs into the stator housing through second circumferential opening  512  when vaned rotor component  509  is rotating in the first cooling direction due to formation of turbulent vortex or other air flow phenomenon adjacent second circumferential opening  512 . Location/s for such a turbulent blocking region may be found, for example, based on empirical test data of blower apparatus of different configurations, by airflow modeling, etc. 
     In a further embodiment, second circumferential opening  512  may be provided with an optional sealing component (e.g., self-closing flapper door  922  that closes due to inward air pressure differential across opening  512 ) to prevent air from being drawn in through the second circumferential opening  512  when rotor component  509  is rotating in the first cooling direction. In the illustrated embodiment of  FIG. 9 , flapper door  922  (e.g., constructed of rubber, plastic, sheet metal, etc.) is illustrated in closed position while rotor component  509  is rotating in the counter clockwise first cooling direction. Upon reversal of rotation of rotor component  509  to the second cleaning direction, air pressure forces flapper door  922  into an open position  922   b  around hinge  920  as shown in  FIG. 10  to allow air to be expelled out second circumferential opening  512  while rotor component  509  is rotating in the clockwise second cleaning direction. An optional closing mechanism, e.g., spring loaded hinge or motorized door actuator, may be provided to help keep flapper door  922  in closed position when rotor component  509  is rotating in the first cooling direction. It will be understood that any other configuration of sealing mechanism may be employed for selectably preventing air from being drawn in through the second circumferential opening  512  when rotor component  509  is rotating in its first cooling direction. 
       FIGS. 11-12  illustrate just a few possible alternative embodiments of self-cleaning blower apparatus  380  having varying locations of second circumferential opening  512  defined in the periphery of stator housing  502  adjacent and continuous with open side  523  of rotor cavity  511 . In this regard, the a particular location for second circumferential opening  512  may be chosen, for example, to fit form factor or other dimensional requirements or a particular application (e.g., particular chassis design). In the event that a selected location for second circumferential opening  512  does not coincide with a turbulent “blocking” region  902 , an optional sealing mechanism (e.g., self-closing flapper door  922 ) may be provided to prevent air from being drawn in through the second circumferential opening  512  when rotor component  509  is rotating in the first cooling direction. It will also be understood that more than one first circumferential opening  510  and/or more than one second circumferential opening  512  may be present in a stator housing component  502 . 
       FIG. 13  illustrates one possible alternative embodiment in which self-cleaning blower apparatus  380  includes a stator housing component  502  with a vaned rotor component  509  having relatively flat-angled vanes  620  coupled thereto to rotate about its center axis  506  relative to stator component  502 . Rotor vanes may be also be configured to be forward-curved, backward-curved or straight relative to the normal first direction of rotation. 
       FIGS. 14 and 15  illustrate a self-cleaning blower apparatus  380  configured according to another exemplary embodiment that is illustrated in a manner similar to the embodiment of  FIGS. 6 and 7 . In the alternative embodiment of  FIGS. 14 and 15 , open side  523  of rotor cavity  511  also does not conform to the outer peripheral shape of vaned rotor  509  and is open to and contiguous with a first circumferential opening  510  defined in the body of the stator housing component  502 . However, closed side  524  defined between the body of stator housing component  502  and rotor component  509  terminates at second circumferential opening  512  which is disposed between closed side  524  of rotor cavity  511  and blocking surface  530  of the body of stator housing component  502  which is conformably located adjacent the outer periphery of rotation of vaned rotor component  509  to from a dynamic pneumatic seal that substantially blocks air flow (i.e., prevents bypass airflow) between the outer periphery of vaned rotor  509  and blocking surface  530 . 
     As shown in  FIGS. 14 and 15 , stator housing cover  802  is configured to cover and at least partially enclose rotor cavity  511 , and includes an axial air opening  804  substantially centered over central rotor member  507  that in this embodiment functions as an air inlet for cooling air when rotor component rotates in its first counterclockwise cooling direction and for cleaning air when rotor component rotates in its second clockwise cooling direction. 
     As further shown in  FIGS. 14 and 15 , a first circumferential opening  510  is defined in the periphery of stator housing  502  adjacent and continuous with open side  523  of rotor cavity  511 . In this exemplary embodiment, first circumferential opening  510  functions as the primary air outlet (i.e., expelling greater than 50% of total expelled air flow from stator housing  502 ) when rotor component  509  rotates in its first counter clockwise cooling direction, although it is not necessary that it be the primary air outlet in all embodiments. The rotating action of rotor  509  creates centrifugal force that dispels air at first circumferential opening  510  in a direction that is oriented 90 degrees from the direction that the air is taken in through axial air opening  804 . First circumferential opening  510  is faced by the oncoming angled front side face  551  of vanes  504  as they move toward open side  523  of rotor cavity  511  against blocking surface  530 , which acts to create an area of higher pressure that forces a majority of the intaken air out first circumferential opening  510 , although it is not necessary that the majority of the intaken air be forced out first circumferential air opening  510  during cooling rotation for all embodiments. As before, when employed in the exemplary information handling system embodiment of  FIG. 5 , first circumferential opening  510  may communicate with the interior of base chassis portion  320  to allow blower apparatus  380  to supply cooling air drawn in through air intake opening  350  through first circumferential opening  510  to the interior components of base chassis portion  320  as shown in  FIG. 14 . It will be understood that dust and other debris may accumulate within rotor cavity  511  during cooling (e.g., counterclockwise) rotation, especially when a grill and/or cooling fins or a heat exchanger are present at first circumferential opening  510 , in which case dust and other debris may accumulate on the surfaces of and/or between the individual fins during cooling rotation. 
     Also illustrated in  FIGS. 14 and 15  is a second circumferential opening  512  that is also defined in the periphery of stator housing  502  that in this embodiment is contiguous with closed side  524  of rotor cavity  511  and positioned between blocking surface  530  and closed side  524  of rotor cavity  511 . Second circumferential opening  512  functions as the primary air outlet (i.e., expelling greater than 50% of total expelled air flow from stator housing  502 ) for blower apparatus  380  when rotor component  509  rotates in its second clockwise cleaning direction as shown in  FIG. 15 , although it is not necessary that second circumferential opening  512  be the primary air outlet during cleaning rotation for all embodiments. The rotating action of rotor  509  creates centrifugal force that dispels air at first circumferential opening  510  in a direction that is oriented 90 degrees from the direction that the air is taken in through axial air opening  804 . Second circumferential opening  512  is faced by the oncoming angled back side face  552  of vanes  504  as they move toward blocking surface  530 , which acts to create an area of higher pressure that forces a majority of the intaken air out second circumferential opening  512 . Since the majority of intaken air is dispelled at second circumferential opening  512  during cleaning (e.g., clockwise) rotation, higher exhaust air pressure and air velocity exists at opening  512  during this time, although it is not always necessary that the majority of intaken air be dispelled at second circumferential opening  512  during cleaning rotation for all embodiments. In any case the change in differential in air pressure between the first and second circumferential air openings  510  and  512  that occurs when switching from cooling rotation to cleaning rotation causes at least a portion of accumulated dust and debris within rotor cavity  511  and/or at associated cooling fins or grill located at first circumferential opening  510  to follow the air pressure gradient and to be exhausted out second circumferential opening  512  during the cleaning (e.g., clockwise) rotation. 
       FIGS. 16-18  illustrate just a few possible alternative embodiments of stator component  502  of self-cleaning blower apparatus  380  having varying configurations of second circumferential opening  512  defined in the periphery of stator housing  502  between closed side  524  and blocking surface  530  of rotor cavity  511 . In  FIGS. 16-18 , rotor component  509  has been omitted from view, and the orientation of blower apparatus  380  reversed such that cooling operation is achieved by clockwise rotation of rotor component  509  and dust cleaning operation is achieved by counterclockwise rotation of rotor component  509 . Additionally,  FIG. 16  illustrates the presence of grill fins  595  at second circumferential opening  512 .  FIG. 18  substantially corresponds to the embodiment of  FIGS. 14-15 , but with the orientation of blower apparatus  380  reversed such that cooling operation is achieved by clockwise rotation of rotor component  509  and dust cleaning operation is achieved by counterclockwise rotation of rotor component  509 . 
     Table 1 below illustrates air flow volume comparison for the embodiments of  FIGS. 16-18 . As may be seen, the embodiment of  FIG. 18  achieves preferential (i.e., majority or greater than 50%) of total air flow out second circumferential opening  512  during cleaning direction rotation of rotor component  509 , in this case 2.75 cubic foot per minute (CFM) cleaning direction air out second circumferential opening  512  as compared to 2.22 CFM cleaning direction air out first circumferential opening  510 . This makes second circumferential opening  512  of  FIG. 18  the primary air outlet during cleaning direction rotation of rotor component  509 . The embodiment of  FIG. 18  also achieves a high ratio of preferential (i.e., majority or greater than 50%) of total cooling air flow out of first circumferential opening  510  during cleaning direction rotation of rotor component  509 , in this case 8.48 CFM cooling air out first circumferential opening  510  and 0.62 CFM cooling air out second circumferential opening  512  during cooling rotation. This makes first circumferential opening  510  of  FIG. 18  the primary air outlet during cooling direction rotation of rotor component  509 . 
     The embodiments of  FIGS. 16 and 17  do not achieve preferential (i.e., majority or greater than 50%) cleaning air flow out second circumferential opening  512  during cleaning rotation, but do achieve the exhaust of some cleaning air out second circumferential air opening  512  during cleaning rotation, while achieving preferential (i.e., majority or greater than 50%) cooling air flow out first circumferential opening  510  during cooling rotation. 
     
       
         
           
               
               
               
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                   
                 FIG. 16 
                 FIG. 17 
                 FIG. 18 
               
            
           
           
               
               
            
               
                   
                 Rotation Direction 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 Cooling 
                 Cleaning 
                 Cooling 
                 Cleaning 
                 Cooling 
                 Cleaning 
               
               
                   
                 Direction 
                 Direction 
                 Direction 
                 Direction 
                 Direction 
                 Direction 
               
               
                   
               
               
                 First 
                 8.29 CFM 
                 2.68 CFM 
                 8.34 CFM 
                 2.99 CFM 
                 8.48 CFM 
                 2.22 CFM 
               
               
                 Outlet 510 
                   
                   
                   
                   
                   
                   
               
               
                 Second 
                 0.69 CFM 
                 1.89 CFM 
                 0.48 CFM 
                 1.89 CFM 
                 0.62 CFM 
                 2.75 CFM 
               
               
                 Outlet 512 
               
               
                   
               
            
           
         
       
     
     It will be understood that one or more of the tasks, functions, or methodologies described herein may be implemented, for example, as firmware or other computer program of instructions embodied in a non-transitory tangible computer readable medium that is executed by a CPU, controller, microcontroller, processor, microprocessor, FPGA, ASIC, or other suitable processing device. 
     For purposes of this disclosure, an information handling system may include any instrumentality or aggregate of instrumentalities operable to compute, classify, process, transmit, receive, retrieve, originate, switch, store, display, manifest, detect, record, reproduce, handle, or utilize any form of information, intelligence, or data for business, scientific, control, entertainment, or other purposes. For example, an information handling system may be a personal computer, a PDA, a consumer electronic device, a network storage device, or any other suitable device and may vary in size, shape, performance, functionality, and price. The information handling system may include memory, one or more processing resources such as a central processing unit (CPU) or hardware or software control logic. Additional components of the information handling system may include one or more storage devices, one or more communications ports for communicating with external devices as well as various input and output (I/O) devices, such as a keyboard, a mouse, and a video display. The information handling system may also include one or more buses operable to transmit communications between the various hardware components. 
     While the invention may be adaptable to various modifications and alternative forms, specific embodiments have been shown by way of example and described herein. However, it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. Moreover, the different aspects of the disclosed apparatus and methods may be utilized in various combinations and/or independently. Thus the invention is not limited to only those combinations shown herein, but rather may include other combinations.