Abstract:
A cooling fan comprising a housing that connects to a computer chassis supporting an electronic component. A fan blade assembly is disposed within the housing. A windings section is fixably mounted within said housing. The windings section forms a body having opposite ends and a bore there between. A first bearing is disposed outboard of one end of the windings section and rotatably supports the fan blade assembly within the housing.

Description:
BACKGROUND  
       [0001]     Computer systems include numerous electrical components that draw electrical current to perform their intended functions. For example, a computer&#39;s microprocessor or central processing unit (“CPU”) requires electrical current to perform many functions such as controlling the overall operations of the computer system and performing various numerical calculations. Generally, any electrical device through which electrical current flows produces heat. The amount of heat any one device generates generally is a function of the amount of current flowing through the device.  
         [0002]     Typically, an electrical device is designed to operate correctly within a predetermined temperature range. If the temperature exceeds the predetermined range (i.e., the device becomes too hot), the device may not function correctly, thereby potentially degrading the overall performance of the computer system. Thus, many computer systems include cooling systems to regulate the temperature of their electrical components. One type of cooling system is a forced air system that relies on one or more cooling fans to blow air over the electronic components in order to cool the components.  
         [0003]     The cubic feet per minute (“CFM”) of air that can be moved across an electric device is an important factor in how much heat can be removed from the device. Thus, the capacity of a cooling fan is a critical factor in selecting an air mover for use in a cooling application. The CFM that a cooling fan can produce is governed a number of factors including: the total area of the blades generating the airflow, the free area provided for airflow through the fan, the design of the blades, and the power generated by the electric motor.  
         [0004]     Electric motors are used to power many cooling fans. Electric motors utilize a cylindrical windings section with magnets disposed inside or outside the cylinder. As electrical current flows through the windings, the magnets rotate about the axis of the motor. The power generated by an electric motor is partially dependent on the size of the windings section. In many computer cooling applications, the size of a cooling fan is constrained, such as by the chassis envelope. Thus, the size of the windings section, and many other components within the fan, are also constrained.  
       BRIEF SUMMARY  
       [0005]     The problems noted above are solved in large part by a cooling fan comprising a housing that connects to a computer chassis supporting an electronic component. A fan blade assembly is disposed within the housing. A windings section is fixably mounted within said housing. The windings section forms a body having opposite ends and a bore there between. A first bearing is disposed outboard of one end of the windings section and rotatably supports the fan blade assembly within the housing. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]     For a detailed description of exemplary embodiments of the invention, reference will now be made to the accompanying drawings in which:  
         [0007]      FIG. 1  shows a cooling fan constructed in accordance with embodiments of the invention;  
         [0008]      FIG. 2  shows a cooling fan constructed in accordance with embodiments of the invention;  
         [0009]      FIG. 3  shows a cooling fan constructed in accordance with embodiments of the invention; and  
         [0010]      FIG. 4  shows a computer system comprising cooling fans constructed in accordance with embodiments of the invention. 
     
    
     NOTATION AND NOMENCLATURE  
       [0011]     Certain terms are used throughout the following description and claims to refer to particular system components. As one skilled in the art will appreciate, computer companies may refer to a component by different names. This document does not intend to distinguish between components that differ in name but not function. In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . .” Also, the term “couple” or “couples” is intended to mean either an indirect or direct connection. Thus, if a first device couples to a second device, that connection may be through a direct connection, or through an indirect connection via other devices and connections.  
       DETAILED DESCRIPTION  
       [0012]     The following discussion is directed to various embodiments of the invention. Although one or more of these embodiments may be preferred, the embodiments disclosed should not be interpreted, or otherwise used, as limiting the scope of the disclosure, including the claims. In addition, one skilled in the art will understand that the following description has broad application, and the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to intimate that the scope of the disclosure, including the claims, is limited to that embodiment.  
         [0013]     Referring now to  FIG. 1 , cooling fan  100  comprises housing  10 , fan blade assembly  20 , bearings  30 , windings section  40 , and circuit board  50 . Blade assembly  20  comprises shaft  22 , hub  24 , blades  26 , and magnets  28 . Bearings  30  comprise an outer, stationary portion  32  and an inner rotating portion  34 . Windings section  40  comprises substantially cylindrical body  42  having two ends  44  and a bore  46  therethrough. Circuit board  50  is electrically coupled to windings section  40  and comprises the electrical circuitry that provides control of the rotation of blade assembly  20 .  
         [0014]     Cooling fan  100  is especially suited for use in cooling electronic components, such as those found in computer systems. Housing  10  is constructed so as to interface with a computer chassis that supports an electronic component. Cooling fan  100  is an axial fan that generates airflow generally along an axis about which blade assembly  20  rotates. Blade assembly  20  is rotated by the interaction of magnets  28  and the magnetic field generated by an electrical current in windings section  40 . Magnets  28  may be connected to hub  24 , as shown, or may be connected to shaft  22  (See  FIG. 3 ).  
         [0015]     Blades  26  extend radially from hub  24 . Shaft  22  is fixed to hub  24  and defines an axis about which blade assembly  20  rotates. Shaft  22  is rotatably supported by bearings  30  and extends through bore  46  of windings section  40 . Bearings  30  are disposed outboard of windings section  40  on ends  44  such that the windings section is between the bearings. Stationary portions  32  of bearings  30  may be connected directly to windings section  40  or may otherwise fixably connected to housing  10 .  
         [0016]     By disposing bearings  30  outboard of windings section  40 , the amount heat that is transferred to the bearings from the windings is decreased. This reduces the temperature at which the bearing operates. The effective life of a bearing is partially dependent on the temperature at which the bearing operates and therefore, by decreasing the heat transferred to the bearings, bearing life can be increased.  
         [0017]     Disposing the bearings outboard of the windings also increases the amount of space available for the windings by removing the bearings from the bore of the windings. The overall size of the windings section can be increased by decreasing the diameter of the bore. Increasing the size of the windings section increases the maximum power that can be generated by the cooling fan. Additional available power allows the fan to be operated at higher speeds, thus providing greater airflow and higher differential pressures.  
         [0018]     Further, because the bearings are not constrained by the bore through the windings section, larger diameter bearings can be used. Larger diameter bearings may provide a longer service life than smaller bearings, may be less expensive to produce, and may permit the use of better lubricants and/or more lubricant volume. Bearings may be ball bearings, sleeve bearings, fluid dynamic bearings, or other type bearings that support rotation of the shaft. In certain embodiments, the bearings may be fully outboard of the windings such that the inner surface of the bearings contacts the outside of the windings and the outer surface contacts the inside of the hub.  
         [0019]     Referring now to  FIG. 2 , cooling fan  200  comprises housing  110 , fan blade assembly  120 , bearings  130 , windings section  140 , and circuit board  150 . Blade assembly  120  comprises shaft  122 , hub  124 , blades  126 , and magnets  128 . Bearings  130  comprise an outer, stationary portion  132  and an inner rotating portion  134 . Windings section  140  comprises substantially cylindrical body  142  having two ends  144  and a bore  146  therethrough. Circuit board  150  is electrically coupled to windings section  140  and comprises the electrical circuitry that provides control of the rotation of blade assembly  120 . Bearings  130  have on outer edge  131  that extends beyond the edge  133  of bore  146  such that the overall size of the bearings is increased and/or the diameter of the bore is reduced.  
         [0020]     Referring now to  FIG. 3 , cooling fan  300  comprises housing  210 , fan blade assembly  220 , bearings  230 , windings section  240 , and circuit board  250 . Blade assembly  220  comprises shaft  222 , hub  224 , blades  226 , and magnets  228 . Windings section  240  comprises substantially cylindrical body  242  having two ends  244  and a bore  246  therethrough. Circuit board  250  is electrically coupled to windings section  240  and comprises the electrical circuitry that provides control of the rotation of blade assembly  220 . Magnets  228  are disposed on shaft  222  and disposed within bore  246  of windings section  240 . Bearings  230  are positioned outboard of windings section  240  and have a larger outer diameter  231  than the diameter  233  of bore  246 .  
         [0021]     Referring now to  FIG. 4 , a computer assembly  350  comprises chassis  302 , motherboard  304 , heat sinks  306 , electronic components  308 , and cooling fans  310 . Each cooling fan  310  comprises a housing  312  surrounding a blade assembly  314  that is rotatably supported by bearings positioned outboard of the windings of the electric motor powers the fan. Cooling fans  310  are arranged so as to generate an airflow that cools electronic component  308 . Heat sinks  306  may be arranged so as to be directly in the airflow generated by fans  310 . Heat sinks  306  are coupled to electronic components so that the heat generated by the electronic component is dissipated to the airflow through the increased surface area of the heat sink.  
         [0022]     The above discussion is meant to be illustrative of the principles and various embodiments of the present invention. Numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. For example, cooling fans as described above may be used in any electronics device that utilizes forced air cooling. It is intended that the following claims be interpreted to embrace all such variations and modifications.