Abstract:
A fluid moving system is disclosed wherein a plurality of stacked blowers may provide for the redundant supply of cooling fluid such as air. This system may be advantageously utilized to cool electronic equipment or other uses. One or more of the blowers may utilize an impellor design that allows for the axial flow of fluid through the blower in addition to a transverse fluid outlet. In addition, the blowers may incorporate a flow gate operative to reduce back flow should a particular blower have a reduced fluid flow.

Description:
FIELD OF THE INVENTION  
         [0001]    The present relates to the field of airflow management and in particular to cooling systems that may be suitable for electronic equipment.  
         BACKGROUND  
         [0002]    Modern day electronic equipment often includes multiple subsystems mounted within a relatively small cabinet for protection and for the convenience of the user. However, such arrangements tend to concentrate large amounts of heat within a constrained area. This heat must be removed for system reliability and safety reasons from the cabinet. Often, the extreme density of electronics within the cabinet necessitates a high airflow rate and relatively high pressure to accomplish the heat removal. In addition, to provide for redundancy and high reliability of the electronic systems, it may be preferred to provide for a heat removal and cooling system that is not totally dependent on a single air mover.  
           [0003]    Centrifugal blade blowers may provide for high pressure and high volume air movement that may be suitable for electronic cooling. However, because of the construction of the impeller typically provided on the blower, it is very difficult and inefficient to provide for redundant blowers for a single cabinet. One difficulty in providing redundant centrifugal blowers is based on the typical construction of the blowers. The centrifugal blowers have impellers that typically have a solid base structure that prevents air from flowing in a direction other than transverse to the inlet. This may dictate that blowers may have to be mounted side by side if redundancy is desired. A side by side mounting may not be desirable due to changes in airflow patterns if an individual blower fails and other reasons  
           [0004]    Therefore, what is needed is an airflow method and apparatus that provides redundancy while sustaining the required total airflow and maintaining the same airflow patterns within a cabinet and other advantages. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]    The invention may be best understood by referring to the following description and accompanied drawings that are used to illustrate embodiments of the invention. In the drawings:  
         [0006]    [0006]FIG. 1 illustrates stacked centrifugal blower according to embodiments of the present invention;  
         [0007]    [0007]FIG. 2 illustrates stacked centrifugal blowers wherein one blower is operational;  
         [0008]    [0008]FIG. 3 illustrates a centrifugal blower mounting system according to embodiments of the present invention; and  
         [0009]    [0009]FIG. 4 illustrates a centrifugal blower having a flow gate coupled to the impeller according to embodiments of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0010]    Referring now to FIG. 1, two centrifugal blowers  101  and  103  are stacked such that the centrifugal blower  103  is mounted above the centrifugal blower  101 . The centrifugal blower  101  has an inlet area  105  and a first exhaust area  107 . Additionally, centrifugal blower  101  has a pass through air passage  109 .  
         [0011]    In like manner, the centrifugal blower  103  has an inlet area  111  and an exhaust area  113 . Also, each of the centrifugal blowers  101  and  103  include an airflow gate  115  and  117  respectively.  
         [0012]    In operation, air is drawn from the inlet  105  of centrifugal blower  101  and exhausted by centrifugal blower  101  through exhaust area  107 . In addition, centrifugal blower  103  draws air through the pass through area  109  in centrifugal blower  101  and into the inlet area  111  of blower  103 . Centrifugal blower  103  then exhausts the air from inlet  111  through exhaust area  113 .  
         [0013]    Exhaust areas  107  and  113  exhaust air into a plenum area indicated generally by  119 . With both centrifugal blowers  103  and  101  operational, the air exhaust gates  115  and  117  are held in an open position by the airflow pressure provided by the centrifugal blowers  101  and  103  respectively.  
         [0014]    As illustrated, airflow as illustrated by arrows  121 , air flows from a bottom area  123  up through the centrifugal blowers and into the plenum area  119 .  
         [0015]    Referring now to FIG. 2, centrifugal blower  101  may have a reduced or zero airflow while centrifugal blower  103  is operational. In this case, air, as illustrated by airflow lines  201 , is pulled by centrifugal blower  103  from area  123  and exhausted into the plenum area  119 . As centrifugal blower  101  has reduced or no airflow, exhaust gates  115  are in a more closed position thereby reducing pressure losses from the plenum area  119  through the centrifugal blower  101 . The exhaust gates  115  may be forced into a more closed position by airflow pressure in the plenum area  119  acting on the outside of the exhaust gate and thereby pushing it toward centrifugal blower  101 . However, other mechanisms are possible also. As an additional example, a spring loaded exhaust gate may be utilized to bias the exhaust gate closed should centrifugal blower  101  have a reduced air flow. It is also possible to attach the exhaust gates to the impeller plate. The gates would then be opened by centrifugal force. Their closure would then be achieved by the weight of the gates pulling the gates down. In other embodiments, the gates may be biased toward a closed position by springs, air pressure or by other force.  
         [0016]    Each of the exhaust gates may also be responsive to open based, in part, on the flow rate of the associated blower. For example, exhaust gates  115  may open, in part or fully, based on the air flow from the centrifugal blower  101 .  
         [0017]    In like manner, centrifugal blower  103  incorporates exhaust gates  117  which may also become in a more closed position should centrifugal blower  103  have reduced or no airflow.  
         [0018]    Exhaust gates  115  and  117  may include a hinge area  203 . This hinge may be incorporated into the exhaust gate. As illustrated, hinge area  203  has a reduced cross section which may tend to create a bendable, or flexible, area. However, other hinge arrangements are also possible. For example, a metal hinge, a fabric hinge, an elastomeric hinge or other hinge may be utilized to achieve the advantageous results.  
         [0019]    Referring now to FIG. 3, an external frame  301  includes spokes  303  and a hub  305 . Additionally, frame  301  includes airflow pass through areas  109 . A centrifugal impellor  309  may be suspended from a motor such a motors  125  and  127  (not shown) by spokes  311 .  
         [0020]    Impellor  309  may be representative of impellers  107  and  113  respectively. The frame  310  may be mounted to an exhaust gates such as exhaust gates  115  and  117  thereby suspending the motor and the attached impellor  309  below the frame. The air pass through areas  109  permit air to pass from the inlet area such as area  105  associated with centrifugal blower  101  to pass axially through the center of the centrifugal blower to a centrifugal blower stacked above it such as the arrangement illustrated in FIGS. 1 and 2 with respect to blowers  101  and  103 .  
         [0021]    Upon the failure or a reduced operating capability of a single centrifugal blower in a stacked arrangement, the operational centrifugal blower may provide the required airflow for cooling or other purposes. Additionally, the speed of an operational centrifugal blower may be adjusted to provide a suitable airflow upon the failure of one or more other centrifugal blowers. Also, while the present method and apparatus is described for providing airflow and pressure, the same system may be utilized to provide for other fluid flow and fluid pressures for the same or other applications.  
         [0022]    Referring now to FIG. 4, blowers  401  and  403  each include an impellers  405  and  407  respectively. Each of the impellers  405  and  407  includes a flow gate  409  and  411  respectively. The flow gates may be coupled to the impellor by an integrated hinge or other attachment. As the impellor spins, the flow gates open allowing air or other flow to occur. The flow gates  409  and  411  may be forced open by centrifugal force, force from the air or other flow, or other force applied to the flow gates. As discussed above, should one of the blowers have reduced air or other flow, the gate may close fully or partially.  
         [0023]    While the present invention has been described with respect to a limited number of embodiments, those skilled in the art will appreciate numerous modifications and variations there from. For example, while two stacked blowers have been illustrated and described, the use of three or more stacked blowers may be utilized. In addition, the air flow of one or both of the blowers may be adjusted individually or collectively to provide for a desired air flow or air pressure for cooling or other purposes. Still additionally, while each blower has been illustrated and described as having a single impeller, other variations may be possible. For example, one or more of the blowers may utilize multiple impellers or impellers and stators. Also, while the blowers have been illustrated and described has only having two exhausts, the one or more of the blowers may be constructed with from one exhaust area to a substantially continuous exhaust area substantially surrounding the impeller(s).  
         [0024]    Therefore, it is intended that the appended claims cover all such modifications and variations that fall within the true spirit and scope of the present invention.